AN ERUPTIVE HISTORY OF MADERAS VOLCANO USING NEW 40Ar/39Ar AGES
AND GEOCHEMICAL ANALYSES
By
Lara N. Kapelanczyk
A THESIS
Submitted in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
(Geology)
MICHIGAN TECHNOLOGICAL UNIVERSITY
2011
Copyright © 2011 Lara N. Kapelanczyk
UMI Number: 1505870
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This thesis, “An Eruptive History of Maderas Volcano Using New 40Ar/39Ar Ages and
Geochemical Analyses,” is hereby approved in partial fulfillment of the requirements for
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Table of Contents
LIST OF FIGURES ................................................................................................................................... vii
LIST OF TABLES .......................................................................................................................................ix
ACKNOWLEDGEMENTS .........................................................................................................................xi
ABSTRACT ............................................................................................................................................... xiii
1.
INTRODUCTION .................................................................................................................................1
2.
GEOLOGIC SETTING ........................................................................................................................3
3.
4.
2.1.
REGIONAL SETTING: CENTRAL AMERICA .........................................................................................3
2.2.
REGIONAL SETTING: NICARAGUA ....................................................................................................3
2.3.
LOCAL SETTING: OMETEPE...............................................................................................................4
2.4.
LOCAL SETTING: MADERAS VOLCANO .............................................................................................5
METHODOLOGY ................................................................................................................................9
3.1.
FIELD METHODS ...............................................................................................................................9
3.2.
THIN SECTIONS .................................................................................................................................9
3.3.
GEOCHEMICAL ANALYSIS METHODS ................................................................................................9
3.4.
40
RESULTS ............................................................................................................................................. 13
4.1.
PETROGRAPHY ................................................................................................................................ 13
4.1.1.
Basalts .................................................................................................................................... 13
4.1.2.
Basaltic Andesites .................................................................................................................. 13
4.1.3.
Andesites and Dacites ............................................................................................................ 14
4.1.4.
Comparison of Phenocryst Mineralogy ................................................................................. 14
4.2.
GEOCHEMICAL ANALYSIS RESULTS ............................................................................................... 16
4.2.1.
General Characteristics ......................................................................................................... 16
4.2.2.
Bulk Composition of Ometepe lavas ...................................................................................... 17
4.2.3.
Incompatible Elements ........................................................................................................... 19
4.2.4.
Fenner Diagrams ................................................................................................................... 22
4.2.5.
Analogy to paired volcanoes of Halsor and Rose (1988)....................................................... 23
4.3.
5.
AR/39AR METHODS ...................................................................................................................... 10
40
AR/39AR RESULTS ........................................................................................................................ 23
DISCUSSION ....................................................................................................................................... 27
5.1.
GEOLOGICAL MAP .......................................................................................................................... 27
5.1.1.
Dominant structural feature: A cross-cutting graben ............................................................ 27
5.1.2.
Existence of an older cone ..................................................................................................... 29
5.1.3.
Alluvial Deposits .................................................................................................................... 29
5.1.4.
Lava Flows ............................................................................................................................. 30
v
5.1.5.
Central Crater and Vents ...................................................................................................... 31
5.2.
GEOCHEMICAL DATA..................................................................................................................... 33
5.3.
40
AR/39AR AGE DATES ................................................................................................................... 35
5.3.1.
Phases of volcanism .............................................................................................................. 35
5.3.2.
Implications of ages for shorelines at Maderas and Concepción.......................................... 35
5.3.3.
Comparison of age dates to other Central American volcanoes ........................................... 36
5.4.
AN ERUPTIVE HISTORY OF MADERAS ............................................................................................. 38
5.5.
IMPLICATIONS FOR GEOLOGIC HAZARDS ........................................................................................ 40
5.5.1.
History of geologic hazards................................................................................................... 40
5.5.2.
Implications for Future Hazards ........................................................................................... 43
6.
FUTURE WORK ................................................................................................................................ 47
7.
CONCLUSIONS ................................................................................................................................. 49
8
REFERENCES.................................................................................................................................... 51
9
APPENDICES ..................................................................................................................................... 57
9.1
APPENDIX A: GEOCHEMICAL DATA ............................................................................................... 57
9.2
APPENDIX B: 40AR/39AR RESULTS.................................................................................................. 68
9.2.1
Sample MADERAS-002 ......................................................................................................... 68
9.2.2
Sample MADERAS-003 ......................................................................................................... 78
9.2.3
Sample MADERAS-004 ......................................................................................................... 88
9.2.4
Sample MADERAS-011 ......................................................................................................... 99
9.2.5
Sample MADERAS-013 ....................................................................................................... 109
vi
List of Figures
FIGURE 1.1: MAP OF CENTRAL AMERICA WITH INSET OF LAKE NICARAGUA AND OMETEPE.. .........................2
FIGURE 2.1: LOCATIONS OF TOWNS AND COMMUNITIES AROUND MADERAS AND EXTENT OF FORESTATION ON
MADERAS.. .............................................................................................................................................6
FIGURE 3.1: 40AR/39AR AND GEOCHEMICAL SAMPLE LOCATIONS BY COLLECTOR AND ROCK TYPE BASED ON
LE BAS ET AL. (1986).. ......................................................................................................................... 12
FIGURE 4.1: PHENOCRYST MINERALOGY OF MADERAS AND CONCEPCIÓN VOLCANOES................................. 16
FIGURE 4.2. TOTAL ALKALIES VS. SILICA FOR OMETEPE ROCKS. .................................................................... 17
FIGURE 4.3. TOTAL ALKALIES VS. SILICA FOR ROCKS FROM CENTRAL AMERICA. .......................................... 17
FIGURE 4.4: SILICA DISTRIBUTION FOR LAVAS FROM MADERAS VOLCANO. ................................................... 18
FIGURE 4.5: SILICA DISTRIBUTION FOR CONCEPCIÓN VOLCANO..................................................................... 18
FIGURE 4.6: SILICA DISTRIBUTION FOR SAMPLES FROM NICARAGUA. ............................................................ 19
FIGURE 4.7. K2O VS. SIO2 FOR CENTRAL AMERICAN VOLCANIC ROCKS. ....................................................... 19
FIGURE 4.8: PLOTS OF INCOMPATIBLE ELEMENTS VS. MGO WITH REGRESSION LINES FOR MADERAS AND
CONCEPCIÓN VOLCANOES. ................................................................................................................... 20
FIGURE 4.9: PLOT OF INCOMPATIBLE TRACE ELEMENTS VS. MGO COMPARING MADERAS AND CONCEPCIÓN
TO OTHER CENTRAL AMERICAN VOLCANOES. ...................................................................................... 21
FIGURE 4.10. FENNER DIAGRAMS FOR CENTRAL AMERICAN VOLCANIC ROCKS. ............................................ 22
FIGURE 4.11 AGE PLATEAU DIAGRAM AND INVERSE ISOCHRON DIAGRAM FOR SAMPLE MADERAS-013. .... 24
FIGURE 5.1: GEOLOGIC MAP OF MADERAS VOLCANO. ................................................................................... 28
FIGURE 5.2: A) SUMMIT PROFILE AND CROSS-SECTION OF MADERAS VOLCANO. ........................................... 29
FIGURE 5.3: SLOPE MAP OF MADERAS VOLCANO IN DEGREES. ....................................................................... 30
FIGURE 5.4. PLOT OF VENT HEIGHT VS. WT. % SIO2. ...................................................................................... 34
FIGURE 5.5: PLOT OF WT. % SIO2 VERSUS AGE OF THE LAVA FLOW. .............................................................. 34
FIGURE 5.6: RANGES OF AGE DATES ANALYZED FOR CENTRAL AMERICAN VOLCANOES. .............................. 37
FIGURE 9.1: AGE PLATEAU FOR MADERAS-002 .......................................................................................... 76
FIGURE 9.2: K-CA PLATEAU FOR MADERAS-002 ........................................................................................ 76
FIGURE 9.3: NORMAL ISOCHRON FOR MADERAS-002 ................................................................................. 77
FIGURE 9.4: INVERSE ISOCHRON FOR MADERAS-002 .................................................................................. 77
FIGURE 9.5: AGE PLATEAU FOR MADERAS-003 .......................................................................................... 86
FIGURE 9.6: K-CA PLATEAU FOR MADERAS-003 ........................................................................................ 86
FIGURE 9.7: NORMAL ISOCHRON FOR MADERAS-003 ................................................................................. 87
FIGURE 9.8: INVERSE ISOCHRON FOR MADERAS-003 .................................................................................. 87
FIGURE 9.9: AGE PLATEAU FOR MADERAS-004 .......................................................................................... 97
FIGURE 9.10: K-CA PLATEAU FOR MADERAS-004 ...................................................................................... 97
FIGURE 9.11: NORMAL ISOCHRON FOR MADERAS-004 ............................................................................... 98
vii
FIGURE 9.12: INVERSE ISOCHRON FOR MADERAS-004 ............................................................................... 98
FIGURE 9.13: AGE PLATEAU FOR MADERAS-011...................................................................................... 107
FIGURE 9.14: K-CA PLATEAU FOR MADERAS-011.................................................................................... 107
FIGURE 9.15: NORMAL ISOCHRON FOR MADERAS-011............................................................................. 108
FIGURE 9.16: INVERSE ISOCHRON FOR MADERAS-011 ............................................................................. 108
FIGURE 9.17: AGE PLATEAU FOR MADERAS-013...................................................................................... 117
FIGURE 9.18: K-CA PLATEAU FOR MADERAS-013.................................................................................... 117
FIGURE 9.19: NORMAL ISOCHRON FOR MADERAS-013............................................................................. 118
FIGURE 9.20: INVERSE ISOCHRON FOR MADERAS-013 ............................................................................. 118
viii
List of Tables
TABLE 4.1: RESULTS OF THIN SECTION ANALYSIS. ......................................................................................... 15
TABLE 4.2. SUMMARY OF 40AR/39AR EXPERIMENTS ....................................................................................... 25
TABLE 5.1: ARTICLES FEATURING STRUCTURAL MAPS OF MADERAS ............................................................. 27
TABLE 9.1: WHOLE-ROCK CHEMICAL ANALYSIS FOR SAMPLES COLLECTED DURING THIS STUDY. ................. 57
TABLE 9.2: GEOCHEMICAL INFORMATION FROM MADERAS VOLCANO (LINDSAY 2009). ............................... 59
TABLE 9.3: RARE EARTH ELEMENT ANALYSES OF MADERAS VOLCANO FROM LINDSAY (2009). ................... 60
TABLE 9.4: WHOLE ROCK AND TRACE ELEMENT ANALYSES OF MADERAS VOLCANO FROM VAN WYK DE
VRIES (UNPUBLISHED). ......................................................................................................................... 61
TABLE 9.5: WHOLE ROCK AND TRACE ELEMENT DATA FOR CONCEPCIÓN VOLCANO FROM VAN WYK DE VRIES
(1993)................................................................................................................................................... 62
TABLE 9.6: RARE EARTH ELEMENTS AT CONCEPCIÓN VOLCANO FROM VAN WYK DE VRIES (1993). ............. 65
TABLE 9.7: WHOLE ROCK AND TRACE ELEMENT ANALYSES FROM CONCEPCIÓN VOLCANO FROM BORGIA AND
VAN WYK DE VRIES (2003) AND FROM CARR AND ROSE (1987). ......................................................... 66
TABLE 9.8: RARE EARTH ELEMENTS AT CONCEPCIÓN VOLCANO FROM CARR AND ROSE (1987). .................. 67
TABLE 9.9: INCREMENTAL HEATING SUMMARY FOR MADERAS-002 ........................................................... 68
TABLE 9.10: NORMAL ISOCHRON TABLE FOR MADERAS-002...................................................................... 69
TABLE 9.11: INVERSE ISOCHRON TABLE FOR MADERAS-002 ...................................................................... 69
TABLE 9.12: RELATIVE ABUNDANCES FOR MADERAS-002 ......................................................................... 70
TABLE 9.13: DEGASSING PATTERNS FOR MADERAS-002 ............................................................................ 71
TABLE 9.14: ADDITIONAL PARAMETERS FOR MADERAS-002 ...................................................................... 72
TABLE 9.15: PROCEDURE BLANKS FOR MADERAS-002 ............................................................................... 73
TABLE 9.16: INTERCEPT VALUES FOR MADERAS-002 ................................................................................. 73
TABLE 9.17: SAMPLE PARAMETERS FOR MADERAS-002 ............................................................................. 74
TABLE 9.18: IRRADIATION CONSTANTS FOR MADERAS-002 ....................................................................... 75
TABLE 9.19: INCREMENTAL HEATING SUMMARY FOR MADERAS-003 ......................................................... 78
TABLE 9.20: NORMAL ISOCHRON TABLE FOR MADERAS-003...................................................................... 79
TABLE 9.21: INVERSE ISOCHRON TABLE FOR MADERAS-003 ...................................................................... 79
TABLE 9.22: RELATIVE ABUNDANCES FOR MADERAS-003 ......................................................................... 80
TABLE 9.23: DEGASSING PATTERNS FOR MADERAS-003 ............................................................................ 81
TABLE 9.24: ADDITIONAL PARAMETERS FOR MADERAS-003 ...................................................................... 82
TABLE 9.25: PROCEDURE BLANKS FOR MADERAS-003 ............................................................................... 83
TABLE 9.26: INTERCEPT VALUES FOR MADERAS-003 ................................................................................. 83
TABLE 9.27: SAMPLE PARAMETERS FOR MADERAS-003 ............................................................................. 84
TABLE 9.28: IRRADIATION CONSTANTS FOR MADERAS-003 ....................................................................... 85
ix
TABLE 9.29: INCREMENTAL HEATING SUMMARY FOR MADERAS-004 ........................................................ 88
TABLE 9.30: NORMAL ISOCHRON TABLE FOR MADERAS-004 ..................................................................... 89
TABLE 9.31: INVERSE ISOCHRON TABLE FOR MADERAS-004 ..................................................................... 89
TABLE 9.32: RELATIVE ABUNDANCES FOR MADERAS-004......................................................................... 90
TABLE 9.33: DEGASSING PATTERNS FOR MADERAS-004 ............................................................................ 91
TABLE 9.34: ADDITIONAL PARAMETERS FOR MADERAS-004 ..................................................................... 92
TABLE 9.35: PROCEDURE BLANKS FOR MADERAS-004 .............................................................................. 93
TABLE 9.36: INTERCEPT VALUES FOR MADERAS-004 ................................................................................ 94
TABLE 9.37: SAMPLE PARAMETERS FOR MADERAS-004 ............................................................................ 95
TABLE 9.38: IRRADIATION CONSTANTS FOR MADERAS-004 ...................................................................... 96
TABLE 9.39: INCREMENTAL HEATING SUMMARY FOR MADERAS-011 ........................................................ 99
TABLE 9.40: NORMAL ISOCHRON TABLE FOR MADERAS-011 .................................................................. 100
TABLE 9.41: INVERSE ISOCHRON TABLE FOR MADERAS-011 ................................................................... 100
TABLE 9.42: RELATIVE ABUNDANCES FOR MADERAS-011....................................................................... 101
TABLE 9.43: DEGASSING PATTERNS FOR MADERAS-011 .......................................................................... 102
TABLE 9.44: ADDITIONAL PARAMETERS FOR MADERAS-011 ................................................................... 103
TABLE 9.45: PROCEDURE BLANKS FOR MADERAS-011 ............................................................................ 104
TABLE 9.46: INTERCEPT VALUES FOR MADERAS-011 .............................................................................. 104
TABLE 9.47: SAMPLE PARAMETERS FOR MADERAS-011 .......................................................................... 105
TABLE 9.48: IRRADIATION CONSTANTS FOR MADERAS-011..................................................................... 106
TABLE 9.49: INCREMENTAL HEATING SUMMARY FOR MADERAS-013 ...................................................... 109
TABLE 9.50: NORMAL ISOCHRON TABLE FOR MADERAS-013 ................................................................... 110
TABLE 9.51: INVERSE ISOCHRON TABLE FOR MADERAS-013 ................................................................... 110
TABLE 9.52: RELATIVE ABUNDANCES FOR MADERAS-013....................................................................... 111
TABLE 9.53: DEGASSING PATTERNS FOR MADERAS-013 .......................................................................... 112
TABLE 9.54: ADDITIONAL PARAMETERS FOR MADERAS-013 ................................................................... 113
TABLE 9.55: PROCEDURE BLANKS FOR MADERAS-013 ............................................................................ 114
TABLE 9.56: INTERCEPT VALUES FOR MADERAS-013 .............................................................................. 114
TABLE 9.57: SAMPLE PARAMETERS FOR MADERAS-013 .......................................................................... 115
TABLE 9.58: IRRADIATION CONSTANTS FOR MADERAS-013..................................................................... 116
x
Acknowledgements
First and foremost I’d like to thank my advisor Dr. Bill Rose for all of his support
throughout this project both while I was in Nicaragua and at Michigan Tech. His help has
been essential to this project. I would also like to thank my other committee members
Benjamin van Wyk de Vries and Greg Waite for their time and expertise.
I would like to thank my Nicaraguan guides for their help and company while in the field:
Javier, Manuel, Norlan, Luis, and Francisco. Thanks to my family and friends in Mérida
for their kindness and acceptance of me into their community. Thanks to Maria Antonia
Mallona and Lisette Carranza at the Peace Corps office who were generous with their
help and always very supportive in allowing me time for my master’s research. Many
thanks to the other staff members of Peace Corps Nicaragua and NICA 48 for countless
other acts of kindness.
Thanks to the many people at Michigan Tech who helped me along the way: Bob Barron,
John Gierke, Amie Ledgerwood, Kelly McLean, Rudiger Escobar-Wolf, and numerous
other graduate students, faculty and staff. It takes a whole department to write a thesis.
Thanks to Brian Jicha at the University of Wisconsin-Madison who dated my samples.
Thanks to Heather Cunningham for helping me prepare the samples, teaching me about
the process, and allowing me to invade her house for a few days. Thanks to Lucie
Mathieu for allowing me to accompany her in the field and for her insights into Maderas
volcano.
Lastly I’d like to thank my family and friends for their support throughout the last four
years. I’d especially like to thank my parents for always supporting my decisions, even
when they continuously take me to far-away places.
This project was funded by the NSF PIRE Grant #0530109.
xi
Abstract
Maderas volcano is a small, andesitic stratovolcano located on the island of Ometepe, in
Lake Nicaragua, Nicaragua with no record of historic activity. Twenty-one samples were
collected from lava flows from Maderas in 2010. Selected samples were analyzed for
whole-rock geochemical data using ICP-AES and/or were dated using the
40
Ar/39Ar
method. The results of these analyses were combined with previously collected data from
Maderas as well as field observations to determine the eruptive history of the volcano and
create a geologic map. The results of the geochemical analyses indicate that Maderas is a
typical Central American andesitic volcano similar to other volcanoes in Nicaragua and
Costa Rica and to its nearest neighbor, Concepción volcano. It is different from
Concepción in one important way – higher incompatible elements. Determined age dates
range from 176.8 ± 6.1 ka to 70.5 ± 6.1 ka. Based on these ages and the geomorphology
of the volcano which is characterized by a bisecting graben, it is proposed that Maderas
experienced two clear generations of development with three separate phases of
volcanism: initial build-up of the older cone, pre-graben lava flows, and post-graben lava
flows. The ages also indicate that Maderas is markedly older than Concepción which is
historically active. Results were also analyzed regarding geologic hazards. The 40Ar/39Ar
ages indicate that Maderas has likely been inactive for tens of thousands of years and the
risk of future volcanic eruptions is low. However, earthquake, lahar and landslide hazards
exist for the communities around the volcano. The steep slopes of the eroded older cone
are the most likely source of landslide and lahar hazards.
xiii
1. Introduction
Maderas is a small (1394 m.a.s.l.), asymmetrical stratovolcano located at 11°26'44"N and
85°30'54"W on the island of Ometepe in Lake Nicaragua, Nicaragua (Figure 1.1). The
dumbbell-shaped Ometepe, which means “two mountains” in the Nahuatl language, is
formed by Maderas and its neighbor, the highly symmetrical stratovolcano Concepción.
Due to its remote location and lack of historic activity, relatively little is known about
Maderas when compared to other Central American volcanoes. Field observations and
hand samples were collected over a one-year period during the author’s two years of
residence, as a Peace Corps volunteer, in Mérida, a small village on the western flanks of
the volcano. Field observations were combined with 21 new geochemical analyses of
Maderas lavas, 88 previously collected geochemical analyses from both Maderas and
Concepción volcanoes, five new
determined
40
40
Ar/39Ar age determinations, and one previously
Ar/39Ar age to create a new geologic map of Maderas and to assess the
eruptive history and hazards posed by the volcano.
Small communities are located around the flanks of Maderas, and, as an island, Ometepe
and its inhabitants are vulnerable to hazards for a number of geographic, social, and
economic reasons. Developing an understanding of the eruptive history of Maderas will
help with the assessment of the hazards on the volcano and will reduce the vulnerabilities
that exist for the communities there.
1
Figure 1.1: Map of Central America with inset of Lake Nicaragua and Ometepe. Dashed lines
represent the boundaries of the Nicaraguan depression (ND) in the south and the Median Trough
(MT) to the north. Triangles represent volcanic centers. Grey lines represent the location of breaks in
strike along the volcanic front. Political boundaries are from GADM (2011).
2
2. Geologic Setting
2.1. Regional Setting: Central America
Maderas is one of 39 Quaternary volcanic centers that form the Central American
volcanic front (CAVF), a 1,100-km chain of volcanoes that range from the GuatemalaMexico border to central Costa Rica, and it is the southernmost of 12 volcanic centers
located in Nicaragua (Carr et al., 2003). The CAVF was formed by subduction of the
Cocos plate moving northeast beneath the Caribbean plate at a rate of 84 ± 5 mm yr-1 near
Nicaragua (DeMets, 2001) (Figure 1.1).
The volcanic centers along the CAVF form 8 segments, each between 100 and 300 km
long. Segments are recognized by linear arrays that form right steps along the volcanic
front (Carr, 1984) (Figure 1.1). The largest of these right steps, ~40 km, occurs between
Maderas volcano and Orosí volcano in Costa Rica and is accompanied by a large change
in depth to the slab from the volcano of ~150 km beneath Maderas to ~80 km beneath
Orosí (Funk et al., 2009). Estimates of the dip angle of the slab below Maderas range
from 65° (Syracuse and Abers, 2006) to 80° (Funk et al., 2009). Both the depth to the
slab and the slab dip generally decrease to the north and south along the CAVF from
Maderas volcano. The crust beneath Maderas is thought to be ~35 km thick (Carr et al.,
2007a).
2.2. Regional Setting: Nicaragua
From west to east Nicaragua is divided into four geological regions: the Pacific Coastal
Plain, the Nicaraguan depression, the interior highlands made up largely of Tertiary
volcanics, and the Atlantic Coastal Plain (McBirney and Williams, 1965). The Pacific
Coastal Plain in southern Nicaragua, near Ometepe, is comprised of Cretaceous to
Oligocene sedimentary rocks (Funk et al., 2009). To the east, the CAVF, including
Maderas, lies within and nearly parallel to a roughly 1,000 km long and 40-70 km wide
depression (Figure 1.1). In the south the depression is known as the Nicaraguan
depression and it runs from the Caribbean coast of central Costa Rica through western
Nicaragua and into El Salvador near the Gulf of Fonseca. Lake Nicaragua and Lake
3
Managua are prominent features of this basin. It continues north from the Gulf of
Fonseca in El Salvador to southern Guatemala as a less geomorphologically-evident
feature, called the Median Trough.
Three tectonic phases have been proposed for the formation of the depression: Miocene
convergence, Pliocene extension, and Pleistocene to present transtensional deformation
(Funk et al., 2009). The initial formation of the depression is thought to have occurred
near Lake Nicaragua during the Oligocene-early Miocene. From there it is thought to
have spread north to the Gulf of Fonseca during the Miocene to Pliocene (Funk et al.,
2009). The actual structure of the depression is still debated due to a lack of information
about the subsurface. Three models have been discussed: the depression formed as an
asymmetrical half-graben (McBirney and Williams, 1965), the depression formed by
large-scale folding (Borgia and van Wyk de Vries, 2003), and the Nicaraguan depression
formed as an asymmetrical graben (Funk et al., 2009).
2.3. Local Setting: Ometepe
Ometepe is ~275 km2 in area and is located in Lake Nicaragua, the largest lake in Central
America, with an area of ~8,000 km2 (Swain, 1966; Freundt et al., 2007). The island
consists of Maderas volcano and its neighbor Concepción volcano, connected by the
Istián isthmus. Concepción volcano is 31 km3 in volume (Carr et al., 2007b), ~1600
m.a.s.l. in elevation, and is historically active with explosions and ashfall occurring as
recently as 2010 (Wilder, 2010). It has been studied extensively by van Wyk de Vries
(1993) and by Borgia and van Wyk de Vries (2003).
Based on the latest census data from Nicaragua taken in 2005 by the National Institute of
Development Information (Instituto Nacional de Información de Desarrollo or INIDE),
approximately 30,000 people inhabit the island of Ometepe (Goffin et al., 2006).
However, in 2010, while Concepción volcano was experiencing gas and ash explosions,
the newspaper La Prensa wrote that the island had a population of 44,000 (Wilder, 2010).
This total likely includes the large number of tourists on the island.
4
The stratigraphy and structure of the rocks of the Pacific lowlands and within the
Nicaraguan depression of southwestern Nicaragua and, therefore, underneath Maderas,
have been described by McBirney and Williams (1965), Borgia and van Wyk de Vries
(2003) and by Funk et al. (2009). The oldest known rock type in the area is the Nicoya
Complex that ranges in age from Jurassic to Cretaceous (de Boer, 1979; Hoernle et al.,
2004). The Nicoya Complex is a suite of igneous rocks (gabbros, plagiogranites, and
basalts) and Mn-radiolarites that are exposed on the Nicoya Peninsula in Costa Rica and
are believed to extend into southern Nicaragua (Denyer and Baumgartner, 2006). Above
the Nicoya Complex lies a sequence of flysch deposits from the Rivas, Brito and
Masachapa formations that were deposited within the Nicaragua depression. These
formations range in age from Cretaceous to Miocene (Borgia and van Wyk de Vries,
2003). Above these units lies the El Salto Formation of Pliocene age and above this lie
the lake sediments deposited by Lake Nicaragua. The lake sediments are estimated to be
up to 1 km thick (Borgia and van Wyk de Vries, 2003).
2.4. Local Setting: Maderas Volcano
Maderas volcano is a small stratovolcano with a sub-conical shape (Grosse et al., 2009),
an estimated volume of 30 km3 (Carr et al., 2007b), a height of 1,394 m.a.s.l., and a
diameter of ~10 km (Borgia and van Wyk de Vries, 2003). In view of the significant
population and the known activity of Concepción, it is important to assess the potential of
activity at Maderas. No historic activity is recorded. Borgia et al. (2000) state that
Maderas has not erupted for at least 3,000 years. The absence of Holocene activity at
Maderas is consistent with its flat summit and extensive exposed faulting on the volcano.
Mathieu (2010) observes that Maderas’ fault structures would have been covered by
eruptive material faster than they could have formed if the volcano had been active
during their formation, as is believed to be the case at Concepción volcano where edifice
faults have been covered by recent eruptions (Delcamp et al., 2008).
The flanks of Maderas are largely deforested and contain more than 20 small towns and
communities (Figure 2.1). Much of the area below 200-300 m.a.s.l. has been altered for
annual cultivation and pasture (Aguirre, 2009). Above 400 m.a.s.l. the volcano is covered
5
by cloud forest. In this humid environment, vegetation is thick and lush and difficult to
navigate without a trail. In the summit crater of the volcano is a small crater lake called
Laguna de Maderas (Maderas Lagoon). As can be seen from the satellite photo (Figure
2.1) a large part of the volcano remains forested. The volcano is listed as a protected area
above elevations of 850 m.a.s.l. called Maderas Volcano Natural Reserve by Nicaragua’s
Ministry of the Environment and Natural Resources (Ministerio del Ambiente y los
Recursos Naturales or MARENA). The entire island of Ometepe has also been recently
declared a Biosphere Reserve as part of the Man and the Biosphere Program by the
United Nations Educational, Scientific and Cultural Organization (UNESCO) (UNESCO,
2010).
Figure 2.1: Locations of towns and communities around Maderas and extent of forestation on
Maderas. The natural reserve represents all land above 850 m on Maderas volcano. The location of a
1996 lahar is also mapped. Image © 2011 Digital Globe, © 2011 TerraMetrics, © 2011 GeoEye, ©
2011 Google.
6
Geological studies of Maderas are limited to investigations of structural features: van
Wyk de Vries and Borgia (1996), van Wyk de Vries and Merle (1996), van Wyk de Vries
and Matela (1998), Borgia et al. (2000), Delcamp et al. (2008), Byrne et al. (2009) and
Andrade and van Wyk de Vries (2010). These papers regard Maderas as an example of a
volcano with a ductile substratum that has undergone spreading. Some papers also
discuss the development of leaf graben structures around the base of the volcano. Van
Wyk de Vries and Borgia (1996) first called attention to Maderas’ spreading due to the
relatively weak lake sediments underlying the volcano. They used a number of physical
parameters to determine dimensionless pi numbers whose ratios were plotted and then
used to measure the “geometric capacity of the system to spread,” the rate of spreading,
and “the state of the elastic stresses within the volcanic edifice built by the last major
eruptive phase.” Their results indicate that Maderas is a fast-spreading volcano with low
collapse hazard and that the elastic stress should be almost completely relaxed within the
volcano. The paper also mentions that little or no evidence of hydrothermal features were
observed at Maderas and identifies a slump feature on the southwest side of the volcano.
Mathieu et al. (2011) describe deformation features on Maderas volcano with respect to a
135° dextral-striking transtensional fault zone using analog models. This fault zone
parallels the summit graben of the volcano. Their findings indicate that the regional stress
field (transtensional fault) and local stress field (spreading) support the formation of a
central conduit and near-radial lineaments around the base of the volcano that are found
in pairs. The 135°-striking fault zone on the volcano is supported by a 25-km-long and 5km wide fault zone described by Funk et al. (2009) that they call the San Ramon Fault
Zone to the SE of Maderas volcano in Lake Nicaragua. Their results suggest a halfgraben structure and this geometry lines up with the graben observed on Maderas
(N45°W).
A geologic map of Maderas volcano was published by the Czech Geologic Service
(Sebesta, 2001) in conjunction with the Nicaraguan Institute of Earth Studies (Instituto
Nicaragüense de Estudios Territoriales or INETER). This map is based on a map created
7
by van Wyk de Vries (1986). In this paper, the geologic map of Sebesta (2001) is updated
using new age dates and geochemical data.
8
3. Methodology
3.1. Field Methods
The goals of field research were to locate, map, and collect samples from lava flows from
a wide range of locations around Maderas representing the entire eruptive history of the
volcano. Sampling sites focused on lava flows that could be identified by field
observations and by lobate geomorphology with the help of Google Earth and digital
elevation models (DEMs). Lava flows were chosen because they represent material that
can be radiometrically dated. Samples selected for dating were chosen to reflect
stratigraphic or geomorphological positions that represent earliest and latest activity of
Maderas.
Twenty-one samples were collected from Maderas volcano from January to September
2010. All samples were believed to be from lava flows except for sample MADERAS
-009, which is a piece of lava rock taken from a debris flow. Sample locations were
obtained using a Global Positioning System (GPS) device. Sample locations can be seen
in Figure 3.1. In each location the freshest, most unaltered sample possible was sought,
however, in many locations it was impossible to find or obtain samples that were not
weathered to some degree.
3.2. Thin Sections
Ten samples were selected for thin section and petrographic study (MADERAS-002,
-003, -004, -007, -008, -011, -013, -015, -017, -018). These same samples were analyzed
for
40
Ar/39Ar age dates (see section 3.4). Thin sections were prepared by the author at
Michigan Technological University.
3.3. Geochemical Analysis Methods
Geochemical analyses for this study were conducted at the Magma and Volcanoes
Laboratory (Laboratoire Magmas et Volcans) at Blaise Pascal University, ClermontFerrand, France. Samples were crushed and pulverized at Michigan Technological
University and then sent to Blaise Pascal University for whole rock chemical analysis of
9
major elements by ICP-AES (inductively coupled plasma atomic emission spectroscopy).
Nineteen samples were selected for analysis from this study (Figure 3.1). Six additional
samples (11-A, 14, 17, 26-B, 39, and 41), collected from Maderas by Lucie Mathieu in
January and February of 2009 while conducting research for her Ph.D. (Mathieu, 2010),
were also prepared and analyzed (Figure 3.1). Thirty-four additional whole rock and trace
element analyses from Maderas volcano were used to characterize the volcano: eighteen
samples from Benjamin van Wyk de Vries (unpublished) and sixteen samples from Fara
Lindsay (Lindsay, 2009) (Figure 3.1). This makes a total of 59 whole rock analyses from
Maderas volcano. It should be noted that samples collected for Lindsay’s study are biased
toward more mafic samples in order to look at source processes.
Fifty-four whole rock and trace element analyses from Concepción volcano were
compared to Maderas: forty-two samples from van Wyk de Vries (1993), six samples
from Borgia and van Wyk de Vries (2003) and six samples from the geochemical
database of Central American volcanoes (http://www.rci.rutgers.edu/~carr/index.html)
maintained by Mike Carr (Carr and Rose, 1987). Tables of all of the Ometepe analyses
can be found in Appendix A.
Additional geochemical samples used for this study include 235 samples from
Nicaraguan volcanic front volcanoes and 336 samples from Costa Rican volcanic front
volcanoes. These analyses were also provided by the database of Central American
volcanoes maintained by Mike Carr (Carr and Rose, 1987).
3.4.
40
Ar/39Ar Methods
Ten samples were selected for
40
Ar/39Ar analysis. These samples were chosen based on
two main factors: lack of weathering and stratigraphic location. The goal was to obtain
high precision dates that would demonstrate the entire age of the volcano, from oldest to
youngest. The locations of samples analyzed for 40Ar/39Ar analysis can be seen in Figure
3.1 as well the location of a previously analyzed sample from Maderas by Carr et al.
(2007b). The following information was provided by Brian Jicha at the University of
Wisconsin-Madison regarding sample preparation and analysis:
10
Samples were prepared at the University of Wisconsin-Madison. Samples
were crushed, sieved to 250-350 µm, and phenocrysts were removed via
magnetic sorting or density separation using methylene iodide.
Microphenocrysts that survived mechanical separation or groundmass
which still showed evidence of alteration were ultimately removed by
hand picking under a binocular microscope. Phenocryst-free groundmass
separates were weighed and then wrapped in 99.99% copper foil packets
placed into in 2.5cm diameter aluminum disks with sanidine from the
28.201 Ma Fish Canyon tuff (Kuiper et al., 2008), which monitors neutron
fluence. Samples and standards were irradiated at the Oregon State
University TRIGA-type reactor in the Cadmium-Lined In-Core Irradiation
Tube (CLICIT) for 1 hour.
At the University of Wisconsin-Madison Rare Gas Geochronology
Laboratory, ~ 200 mg groundmass packets were incrementally heated in a
double-vacuum resistance furnace attached to a 300 cm3 gas clean-up line.
Prior to sample introduction, furnace blanks were measured at 100 °C
increments throughout the temperature range spanned by the incremental
heating experiment and interpolated. Following blank analyses, samples
were degassed at 550 °C for 60 minutes to potentially remove large
amounts of atmospheric argon. Fully automated experiments consisted of
9-10 steps from 650-1250 °C; each step included a two-minute increase to
the desired temperature that was maintained for 15 minutes, followed by
an additional 15 minutes for gas cleanup. The gas was cleaned during and
after the heating period with three SAES C50 getters, two of which were
operated at ~450 °C and the other at room temperature. Argon isotope
analyses were done using a MAP 215-50 mass spectrometer using a single
Balzers SEM-217 electron multiplier, and the isotopic data was reduced
using ArArCalc software version 2.5 (Koppers, 2002). The age
uncertainties reported for each individual sample are at the 95%
11
confidence level, and the decay constants used are those of Min et al.
(2000).
Figure 3.1: 40Ar/39Ar and geochemical sample locations by collector and rock type based on Le Bas et
al. (1986). Note that some sample names are repeated (i.e. M1 and M1). Both van Wyk de Vries
(unpublished) and Lindsay (2009) used the same naming system for their samples.
12
4. Results
4.1. Petrography
The hand samples and thin sections collected for this project reveal that lavas from
Maderas are largely porphyritic with the majority of samples having between 25-30%
plagioclase phenocrysts. A high abundance of phenocrysts is consistent with lavas found
elsewhere in Central America (Carr et al., 1982). All samples with thin sections contain
plagioclase, olivine, clinopyroxene, apatite and opaque phenocrysts. Some samples also
contain orthopyroxene, amphibole, and biotite. Zoning is common within the plagioclase
phenocrysts as has been observed at other Central American lavas as well (Carr et al.,
2007a). Table 4.1 shows the results of the petrographic analysis.
4.1.1. Basalts
Of the 59 sample analyses from Maderas used for this study, 24 are basalts. To account
for duplicate samples of the same rock unit based on the geologic map (see section 5.1)
or duplicate analyses, 46 samples are used to determine the percentage of each rock type.
The percentage of basalts is ~33% (15 of 46 samples). There are 3 thin sections of basalts
(MADERAS-004, -008, and -017). All three thin sections display high percentages of
plagioclase phenocrysts (25-45%) ranging in size from fine to medium grained and often
displaying twinning and/or zoning. Other phenocrysts include clinopyroxene (<1-5%),
olivine (~1%), and small percentages of opaques (<1%). Two of the samples also contain
small percentages of orthopyroxene (~1%).
4.1.2.
Basaltic Andesites
Basaltic andesites represent ~30% or 14 of the 46 analyses. Of those there are 3 thin
sections of basaltic andesite (MADERAS-002, -011, and -018). Phenocrysts present in all
three thin sections include plagioclase (20-30%), olivine (~1%), clinopyroxene (<1-3%),
and opaques (<1%). Two of the thin sections contain orthopyroxene (<1-3%). Twinning
and zoning are common in the plagioclase phenocrysts. Phenocrysts are mostly fine
grained with plagioclase ranging in size from fine to medium grained.
13
4.1.3. Andesites and Dacites
Andesites/trachy-andesites represent ~28% or 13 of the 46 rock analyses and
trachydacites represent ~9% or 4 of the 46 analyses. Thin sections of two trachyandesites (MADERAS-013 and -015) and two trachydacites (MADERAS-003 and -007)
were investigated. All four thin sections contain phenocrysts of plagioclase,
orthopyroxene (<1-2%), clinopyroxene (<1-2%), olivine (<1%), and opaques (<1-1%).
MADERAS-013 and -015 also contain phenocrysts of biotite (<1%) and sample -013
also has phenocrysts of amphibole (<1%).
Phenocrysts range in size from medium- to fine-grained with the majority of phenocrysts
being fine grained. Zoning and twinning is common amongst plagioclase phenocrysts and
twinning is sometimes encountered amongst clinopyroxene grains. Plagioclase
phenocrysts are 20-30% of the rock in the trachy-andesites (MADERAS-013 and
MADERAS-015) while they make up only 3-5% in the trachydacites (MADERAS-003
and MADERAS-007). Sample MADERAS-007 is highly vesicular.
4.1.4. Comparison of Phenocryst Mineralogy
Phenocryst mineralogy for Maderas and Concepción volcanoes was compared to other
Central American volcanoes. A graphical summary of phenocryst mineralogy for Central
American volcanic rocks using data from Carr et al. (1982) was created (Figure 4.1). The
ranges of SiO2 contents found at Maderas and Concepción are plotted. Differences from
the other nearby volcanoes are minor. At Maderas olivine was found in the andesites (up
to 61.43% SiO2). At Concepción, orthopyroxene was not found above 62% SiO2 and
amphibole was seen only in dacites (van Wyk de Vries, 1993). It is concluded that the
mineralogy at Maderas is similar to other nearby volcanoes.
14
15
f-m
4045
f-m
2530
trachydacite
basalt
trachydacite
basalt
basaltic
andesite
trachyandesite
trachyandesite
basalt
basaltic
andesite
MADERAS-003
MADERAS-004
MADERAS-007
MADERAS-008
MADERAS-011
MADERAS-013
MADERAS-015
MADERAS-017
MADERAS-018
f-m
5
f
1
f-m
<1
f
1
f
<<1
fm?
3-5
f-m
3540
f-m
3
f-m
<1
f
2
<<1
f
<<1
f-m
2-3
f
1
<1
f-m
f
<1
<1
<1
f
f
f
f
<1
1
2-3
f-m
2
f
1-2
f-m
<1
f
<1
f
<1
f
1
f-m
<1
f
opx
<1
f
<<1
f
1
f
1
f
<1
f
<1
f
<<1
f
<<1
f
<1
f
1
f
opaques
<<1
f
<<1
f
biotite
<<1
f
<1
f
amph
intersertal
intersertal
intersertal
intersertal
intersertal,
poikalitic
intersertal
intersertal,
trachytic
intersertal
intersertal
inersertal
Groundmass
Texture
1. pl=plagioclase, ol=olivine, cpx=clinopyroxene, opx=orthopyroxene, amph=amphibole)
2. phenocrysts sizes: f=fine grained (<1mm), m=medium grained (1-5mm)
3. alteration is based on percentages of secondary minerals: 0-25% = low, 25-50% = med., and >50% = high
2530
f-m
2530
f-m
2025
f-m
2530
f
f
<1
1-2
f-m
<1
f-m
cpx
3035
f-m
f-m
basaltic
andesite
MADERAS-002
ol
pl
Rock Type
Sample Number
Phenocrysts1 (Size2 and Whole Rock Percentages)
Table 4.1: Results of thin section analysis.
high
X
X
med.
Alteration3
X
X
X
X
X
X
X
X
low
X
X
X
X
Vesicles
X
X
Zeolites
Concepción
Maderas
ol
cp
op
hb
bi
pl
qt
kf
cu
ma
il
ap
?
?
50
55
65
60
Wt. % SiO2
70
75
Figure 4.1: Phenocryst mineralogy of Maderas and Concepción volcanoes. Values of wt. % SiO2 for
each mineral are from Carr et al. (1982) and represent common phenocryst mineralogy for Central
America. Solid lines indicate the mineral is usually present, dashed lines indicate the mineral is
sometimes present. Symbols: ol = olivine, cp = clinopyroxene, op = orthopyroxene, hb = hornblende,
bi = biotite, pl = plagioclase, qt = quarts, kf = potash feldspar, cu = cummingtonite, ma = magnetite, il
= ilmenite, ap = apatite.
4.2.
Geochemical Analysis Results
4.2.1. General Characteristics
Major element oxide analysis results can be found in Appendix A. The volcanic rock
classification of LeBas et al (1986) shows that Maderas rocks include basalts, basaltic
andesites, and the more silicic rocks are on both sides of the divide between andesites and
trachyandesites, while the highest silica rocks are trachydacites (Figure 4.2). This
distribution of rock types differs from Concepción, where most all of the rocks are basalt,
basaltic andesite, andesite and dacite (Figure 4.2). Figure 4.3 shows the same plot but
includes samples from volcanoes in Nicaragua and Costa Rica. The Maderas and
Concepción samples show the same range in composition (basalt to dacite) as other
Central American (CA) volcanoes based on silica content.
16
LeB as et al 1986 N M 100
16
P honolite
14
T ephriphonolite
12
10
N a2O +K2O
Foidite
8
6
4
2
0
35
40
T rachyte
P honoT ephrite
T rachy- T rachydacite
R hyolite
andesite
B asaltic
T ephrite or
trachyB asaniteT rachy-andesite
basalt
D acite
A ndesite
B asaltic
B asalt
andesite
P icrobasalt
45
50
55
60
65
70
75
S iO2
Figure 4.2. Total alkalies vs. silica for Ometepe rocks.
LeB as et al 1986 N M 100
16
P honolite
14
T ephriphonolite
12
10
N a2O +K2O
8
Foidite
6
4
2
0
35
40
T rachyte
P honoT ephrite
T rachy- T rachydacite
R hyolite
andesite
B asaltic
T ephrite or
trachyB asaniteT rachy-andesite
basalt
D acite
A ndesite
B asaltic
B asalt
andesite
P icrobasalt
45
50
55
60
65
70
75
S iO2
Figure 4.3. Total alkalies vs. silica for rocks from Central America.
4.2.2. Bulk Composition of Ometepe lavas
Figure 4.4 shows the silica distribution of Maderas rocks as represented by the whole
rock data in Appendix A. The 59 whole rock analyses describe a typical andesitic
volcano with a mean SiO2 percentage of 54.4 ± 4.1 %. The range is from 48 to 64 %. The
distribution is likely slightly skewed toward the mafic end because one of the
investigators (Lindsay, 2009)sampled mafic materials selectively for petrological reasons.
17
Figure 4.5 shows the silica distribution for Concepción volcano. Concepción has an
almost identical silica range and distribution as Maderas, with a mean at 55.2 ± 4.5 % and
a slightly larger range of 48 to 66 % SiO2.
Distribution plots from Maderas and Concepción can be compared with the distribution
plot for Nicaragua samples in Figure 4.6. Based on the samples collected, Nicaraguan
volcanic rocks (including Maderas and Concepción) have a mean of 53.7 ± 5.0 % and a
range of 47-68%. This is also nearly identical to Maderas and shows that the bulk
composition of Maderas is similar to other nearby volcanoes.
N =59 M =5.44E+1 SD =4.09E+0 SE=5.32E-1
26
24
22
20
18
16
F requency14
12
10
8
6
4
2
0
45
50
55
60
65
70
S iO2
Figure 4.4: Silica distribution for lavas from Maderas volcano.
N =54 M =5.52E+1 SD =4.49E+0 SE=6.11E-1
15
14
13
12
11
10
9
Frequency
8
7
6
5
4
3
2
1
0
45
50
55
60
65
S iO2
Figure 4.5: Silica distribution for Concepción volcano.
18
70
N =235 M =5.37E+1 SD =4.96E+0 SE=3.23E-1
65
60
55
50
45
40
35
F re qu e n cy
30
25
20
15
10
5
0
45
50
55
60
65
70
S iO2
Figure 4.6: Silica distribution for samples from Nicaragua.
4.2.3. Incompatible Elements
Maderas lavas differ from Concepción in one significant way. They are higher in
incompatible elements. Figure 4.3 shows that Maderas and Concepción display higher
amounts of alkalies than other Nicaraguan and Costa Rican volcanoes when plotted
against SiO2 and that Maderas displays higher amounts than Concepción. A plot of K2O
vs. SiO2 (Gill, 1981) highlights this trend with the Maderas samples exhibiting higher
concentrations of incompatible potassium (High-K) than most other Nicaraguan and
Costa Rican volcanoes (Figure 4.7). The Concepción samples are found along the high
end of the Medium-K rocks.
A n d e s ite ty p e s
4
A C ID
3
B A S IC
H ig h -K
K 2O 2
M e d iu m -K
1
L o w -K
0
50
55
60
65
S iO2
Figure 4.7. K2O vs. SiO2 for Central American volcanic rocks.
19
Plots of incompatible elements vs. MgO for Maderas and Concepción can be seen in
Figure 4.8. For comparable MgO ranges, Maderas lavas are higher in K2O, Rb, Zr, Nb,
and Th than Concepción. This difference amounts to Maderas enrichments of about 2050%, but this enrichment is not shared by Ba. This enrichment may reveal a more
evolved magmatic system below Maderas than the system below Concepción but the
cause of Maderas’ incompatible element enrichment is beyond the scope of the study.
In Figure 4.9, incompatible elements at Maderas and Concepción are compared to other
volcanoes from Nicaragua and Costa Rica. For MgO ranges similar to Maderas and
Concepción (0-6 wt. %) Nicaraguan and Costa Rican volcanoes show similar ranges of
incompatible elements with some Costa Rican volcanoes displaying the highest
concentrations. Samples from Maderas and Concepción fall within this range. Above 6
wt. % MgO the Nicaraguan and Costa Rican volcanoes bifurcate with Costa Rican
volcanoes always displaying higher values.
5
Concepcion
Maderas
4
3000
Concepcion
Maderas
2000
3
K2O
Ba
2
1000
1
0
100
0
500
400
75
300
Rb
Zr
50
200
25
100
0
50
0
20
40
15
30
Nb
10
Th
20
5
10
0
0
1
2
3
MgO
4
5
6
0
1
2
3
MgO
4
5
6
0
Figure 4.8: Plots of incompatible elements vs. MgO with regression lines for Maderas and
Concepción volcanoes.
20
5
3000
Nicaragua
Concepcion
Maderas
Costa Rica
4
2000
3
Ba
K2O
2
1000
1
0
500
0
200
400
300
Zr
Rb 100
200
100
0
40
0
70
60
30
50
Nb
40
20
30
20
Th
10
10
0
0
1
2
3
4
5
6 7
MgO
8
9
10 11 12
0
1
2
3
4
5
6
MgO
7
8
9
10
11
12
0
Figure 4.9: Plot of incompatible trace elements vs. MgO comparing Maderas and Concepción to
other Central American volcanoes.
While new trace element data was not analyzed for the samples collected in this study
other than Ba and Sr, previous studies of trace elements from Central America show that
Nicaragua has a regional high for degree of melting and fluid from the subducted slab
based on Ba/La and La/Yb ratios (Bolge et al., 2009). However, this applies only to
western Nicaragua and as you move south these ratios decrease steadily towards Maderas
and Concepción to show some of the lowest values in slab signal and degree of melting in
Central America, other than in central Costa Rica. Trace element ratios also indicate that
while most of the magmas along the CAVF are derived from water-rich flux, at Maderas
and Concepción there is also a component of decompression melting due to the steep dip
of the slab (Carr et al., 2007b; Lindsay, 2009).
21
4.2.4. Fenner Diagrams
Fenner diagrams comparing Maderas and Concepción to other Nicaraguan and Costa
Rican volcanoes are presented below (Figure 4.10). The rocks from Maderas and
Concepción volcanoes display smaller ranges of MgO (0-6 wt. %) than all the
Nicaraguan and Costa Rican volcanoes (0-12 wt. %). However, within their range they
display similar values for the other element oxides indicating that they are typical Central
American volcanoes.
22
65
Nicaragua
Concepcion
Maderas
Costa Rica
60
Al 2 O 3 17
55
SiO
2
50
12
20
45
2.0
1.5
FeO
10
1.0
TiO
2
0.5
0
6
0.0
15
4
10
Na 2 O
CaO
2
5
0
4
0
1.0
K2O 2
0.5
0
10
5
0
10
5
0
P2O5
0.0
MgO
MgO
Figure 4.10. Fenner diagrams for Central American volcanic rocks. (All FeO as FeO*.)
22
4.2.5. Analogy to paired volcanoes of Halsor and Rose (1988)
Due to the close proximity of Maderas volcano to Concepción volcano, the two were
compared to superficially similar paired volcanoes in northern Central America (NCA
pairs) studied by Halsor and Rose (1988). The NCA pairs (Cerro Quemado-Santa Maria,
Tolimán-Atitlán, Acatenango-Fuego, and Santa Ana-Izalco) straddle the volcanic front
whereas Maderas and Concepción are arranged parallel to the front. Dollfus and de
Montserrat (1868) and others who have described volcanoes in Guatemala have observed
that volcanic front volcanoes seem to be migrating spatially to the south, as marked by
younger, more active southerly cones which are spatially near older northern vents. This
suggested that the volcanic front, and perhaps the trench and subduction zone, might be
migrating southward.
This has not been suggested for Nicaragua, however. In addition, in Northern Central
America there are silicic calderas located north of the VF (Rose et al., 1999) and so the
northerly position of the older vents suggests that the high incompatible element content
could be influenced by mixing with silicic magma bodies of the caldera. This is unlikely
to apply at Ometepe, where there is as yet no evidence of a silicic center. However,
Maderas does share characteristic incompatible element enrichments along with the older
cones of NCA (all except Ba, Figure 4.8). It is concluded that while there are some
similarities to NCA pairs, it is unlikely that they share completely similar explanations.
4.3.
40
Ar/39Ar Results
A summary of the results of the 40Ar/39Ar analyses can be found in Table 4.2. Of the ten
samples prepared for analysis, seven samples were analyzed. Two samples (MADERAS007 and -008) did not define an age plateau and are not included in the table. The
remaining five samples revealed ages that range from 70.4 ± 6.1 ka to 176.8 ± 6.1 ka. The
ages for samples MADERAS-002, -003, -011, and -013 are precise with uncertainties of
1.4%-8.6%. The age determined for sample MADERAS-004 is less precise with a
(±17%), which may be due to alteration. These ages are consistent with the previous agedate obtained for Maderas of 76±6 ka (Carr et al., 2007b) which is also included in the
23
table. An example of an
40
Ar/39Ar age determination can be seen in Figure 4.11. For
complete results of the 40Ar/39Ar age determinations see Appendix B.
500
(a)
450
400
350
300
250
200
85.2 ± 3.1 Ka
150
100
50
0
50
100
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
0.0045
(b)
0.0040
0.0035
0.0030
0.0025
0.0020
0.0015
0.0010
85.1 ± 3.8 Ka
0.0005
0.0000
0
1
1
2
2
3
3
4
4
5
5
6
6
7
7
39Ar / 40Ar
Figure 4.11 Age plateau diagram (a) and inverse isochron diagram (b) for sample MADERAS-013.
24
25
0.43
1.88
0.13
1.69
0.37
-
MAD002
MAD013
MAD004
MAD003
MAD011
2
-
175.5
157.7
125.8
85.1
68.1
-
± 8.6
± 3.5
± 30.9
± 4.7
± 7.2
Total fusion
Age (ka) ± 2σ
-
295.5
296.3
295.0
295.6
293.4
-
± 5.2
± 7.0
± 1.7
± 2.4
± 5.5
Ar/36Ari ± 2σ
40
-
0.21
0.23
0.23
0.28
0.31
MSWD
-
176.8
157.1
136.5
85.1
73.2
-
± 9.1
± 3.7
± 3.8
±
33.4
± 9.4
Isochron
Age (ka) ± 2σ
-
9
9
9
10
9
-
of
of
of
of
of
N
-
9
9
10
10
9
-
100.0
100.0
95.7
100.0
100.0
Ar %
39
-
0.19
0.21
0.25
0.25
0.34
MSWD
76.0
176.8
157.5
128.7
85.2
70.4
± 12.0
± 6.1
± 2.2
± 22.2
± 3.1
± 6.1
Plateau
Age (ka) ± 2σ
3
Qal
Qprba
Qpra
Qprgb
Qpoa
Qpoba
Geologic
Unit1
Ages calculated relative to 28.201 Ma for the Fish Canyon sanidine (Kuiper et al., 2008) using decay constants of Min et al. (2001).
Age in bold is preferred.
All uncertainties are given at 95% confidence level.
1
Geologic unit refers to Figure 5.1
2
For more information on sample M10 see Carr et al. (2007)
3
Plateau age has been modified from Carr et al. (2007) from 76.0 ± 6.0 to 76.0 ± 12.0 to account for the difference in uncertainty reporting between the two studies (2σ
for this study and 1σ for Carr et al.).
M10
K/Ca
total
Sample #
Table 4.2. Summary of 40Ar/39Ar experiments
5. Discussion
5.1. Geological Map
As a framework for gaining the full significance of age dates, geochemical data, sample
locations and field observations, a geologic map of Maderas volcano was constructed
(Figure 5.1). Previous geologic maps by Sebesta (2001) and van Wyk de Vries (1986)
were consulted while constructing this map. For structural features the structural maps in
the articles found in Table 5.1 were consulted. Topographic maps of the island (INETER
and JICA, 2006b; INETER and JICA, 2006a), Google Earth images, and a 20m DEM
were also used in the mapping process. The new map is discussed below along with the
differences from previous maps.
Table 5.1: Articles featuring structural maps of Maderas
Article
van Wyk de Vries and Borgia (1996)
van Wyk de Vries and Merle (1996)
Borgia et al. (2000)
Kerle and van Wyk de Vries (2001)
Delcamp et al. (2008)
Byrne et al. (2009)
Mathieu et al. (2011)
5.1.1. Dominant structural feature: A cross-cutting graben
As discussed above, a graben striking 135° cuts across the center of the volcano. The
main faults are evidently normal. These faults bound an asymmetrical graben with over
100 meters of vertical displacement on the eastern fault and over 50 meters of vertical
displacement on the western fault. The graben created a topographic low along the
summit of the volcano. A cross section and summit profile can be seen in Figure 5.2.
When volcanism occurred after the formation of this graben, the erupted lava
accumulated and flowed along the strike of the graben creating a flatter top to the volcano
and less steep slopes to the north and south. The feature is clearly delineated by the
differential erosion where inside the graben the younger deposits are less deeply incised.
27
28
Figure 5.1: Geologic map of Maderas volcano. SRFZ = San Ramon Fault Zone. Location of SRFZ determined by (Funk et al., 2009).
a)
b)
A’
A
Figure 5.2: a) Summit profile and cross-section of Maderas volcano. Vertical exaggeration is ~1.5x.
Light grey lines represent a general orientation of volcanic deposits. The blue area represents alluvial
deposits b) Location of A and A’ on Maderas volcano.
5.1.2. Existence of an older cone
Following the previous discussion of the cross-cutting graben, Maderas volcano has a flat
summit with relatively steep western and eastern flanks. A map of the slope of the
volcano (Figure 5.3) shows that the area west of the summit crater and east-northeast of
the summit graben have the steepest slopes on the volcano with an average gradient of
~24° on the east side and a gradient of ~25° on the west side. For comparison, the slopes
of Concepción volcano have a gradient of ~28°. This topography is interpreted to
represent an older cone that was eroded and breached by the graben. The east and west
flanks apparently represent the slopes of the cone before faulting and are composed of the
oldest exposed flows on the volcano. The depth of the erosional channels and gullies in
these areas suggest that there have not been any new lava flows or deposits on these
slopes for an extended period of time. This is consistent with the dense forest cover found
on these slopes that is nearly impossible to traverse without a trail.
5.1.3. Alluvial Deposits
Large alluvial deposits are found around the base of the volcano with the most
voluminous deposits on the east and west sides of the volcano (Figure 5.1). The majority
of these deposits are found downslope of the extensively eroded older cone. It is likely
29
that the erosion of the older cone, at times in the form of lahars, is the origin of these
deposits. A gradational contact has been mapped between the old cone and the deposits.
Other depositional features are an alluvial fan on the south side of the island near the
town of Tichaná, streambeds where sediments have been deposited, and lacustrine
deposits from Lake Nicaragua on the isthmus between Maderas and Concepción volcano.
5.1.4. Lava Flows
Lava flows that have been emplaced on the volcano after the formation of the old cone
largely radiate out from the central crater (Figure 5.1). These lava flows can be broken up
into pre-graben flows and post-graben flows. Pre-graben flows are found on the east and
west side of the volcano emanating from the older cone. Where lava flows can be
observed on the lower slopes in these areas they have been traced up the flanks of the
volcano if possible. This indicates that the pre-graben flows are younger than the older
cone as their traces mantle the older cone.
Figure 5.3: Slope map of Maderas volcano in degrees.
30
Lava compositions from the pre-graben flows vary from basalt to dacite, which differs
from the map by Sebesta (2001) where all of the lava flows were mapped as andesite.
Some flows that were mapped do not have geochemical data associated with them and
have been mapped as having unknown compositions. There is some uncertainty about the
exact contacts between lava flows in some areas. Where uncertainty exists a dashed line
has been used.
Post-graben flows are found to the north and south of the volcano emanating from the
summit crater along the strike of the graben. As the graben formed it created a
topographic low to the north and south causing the flows to move in these directions. The
compositions of these flows based on geochemical data are basaltic to andesitic.
5.1.5. Central Crater and Vents
Knowledge about rock materials near Maderas’ summit is limited by strong weathering
and heavy vegetation cover in an area receiving orographic rainfall. The central vent of
Maderas volcano contains a small lake and is located roughly in the center of the volcano,
within the graben, and along its west side (Figure 5.1). On the west side of the central
crater is a debris avalanche deposit. The east side of the crater had thick vegetation but
possible lava flows are present.
Two other vents can be seen on the northeast side of the volcano. One vent is located in
an area known as Punta Gorda and the other is southeast of Punta Gorda near the town of
El Corozal. Punta Gorda can be divided into two areas, a northern area and a southern
area. The northern-most area at Punta Gorda has a semi-circular shape, a topographic
high towards the northern edge of the point and is cut by a fault. Near the northern coast
of this area and at the topographic highs there are many large boulders of lava. The
largest are ~1.5 m in diameter with an average diameter being ~40 cm. Mathieu (2010)
also found a phreatomagmatic deposit on the southwest side of this area; however, it is
possible it is associated with the more southern area on Punta Gorda.
The southern area on Punta Gorda has a semi-circular shape and a flat central crater with
a rim around it except for an area on the eastern side along the lakeshore. This rim is
31
highest on the southwest side (~100 m.a.s.l.). A phreatomagmatic deposit is located in
this same area as well as on the eastern side along with a lava flow (Mathieu, 2010). The
flat central crater is roughly 0.8 km in diameter.
Based on the description above, it is proposed that a lava flow descended from the
summit crater of the volcano and started to form a terrace over the lake in the area of
Punta Gorda. This terrace collapsed in the southern area of the point and reacted with
water creating a littoral maar, or rootless vent feature. Lava flows that appear to have
flowed down the side of the volcano to this littoral maar have been mapped in the area
upslope from Punta Gorda by Sebesta (2001) and were mapped in this study as well,
supporting this theory.
A similar situation is thought to have occurred near El Corozal to the southeast where
another semi-circular flat, central crater is located near phreatomagmatic deposits. A
lateral vent, located upslope at about 200 m.a.s.l, is thought to have erupted an andesitic
to dacitic lava near the lakeshore. When this flow reached the water, it reacted with it
forming another littoral maar, or rootless vent feature.
A second lateral vent is located on the northwestern slope of the volcano above the
community of El Tistero. This vent appears to have erupted several lava flows. Sebesta’s
map indicates that this vent is a maar feature, however no hydrothermal features were
found during field observations of this area. Also an investigation into the past lake levels
of Lake Nicaragua did not reveal much as little information is available regarding this
subject. One article did imply that during the mid to late Pleistocene the lake was larger,
reaching down into northern Costa Rica, which could indicate higher lake levels
(Bergoeing and Protti, 2006), however the vent sits at around 350 m.a.s.l. and it is highly
unlikely that lake levels ever reached that high. Also, the lack of hydrothermal deposits
makes it unlikely that water played a role in this vent.
One other possible vent located in this study is Punta el Delirio on the north-northwest
side of the volcano. However, too little information was collected during this study to
determine whether or not this is a littoral vent.
32
Mathieu et al. (2011) also proposed two more vents near the summit of the crater (one to
the southwest and one to the north) and one other vent south of Punta el Delirio. Van
Wyk de Vries and Borgia (1996) also proposed a vent at Punta El Delirio as well as more
vents in the Punta Gorda area. No evidence was found during this study to support the
presence of these vents.
5.2. Geochemical Data
As the stature of stratovolcanoes increases their silica content may also rise. To evaluate
the geochemical evolution of the volcano, plots of vent elevation versus silica content
were made (Figure 5.4). Excluding the two mapped lateral vents, we see a weak tendency
for trachy-andesites/trachydacites to be erupted from vents higher up on the volcano. It
should be noted that many flows are not plotted, as it is not possible to tell from which
height they were erupted due to their location beneath younger flows.
To determine if the lava flows at the volcano became more evolved over time a plot of
lava flow age vs. silica content was created using known age dates and stratigraphy
(Figure 5.5). Lava flows were first divided up by known age dates and by map unit (old
cone, pre-faulting flow or post-faulting flow, Figure 5.1). Within each unit, flows that
were known to be stratigraphically younger or older than the dated flows were added.
Remaining flows with geochemical data were then placed. In many cases uncertainty
exists about relative ages of these flows. This plot reveals no apparent correlation
between age and silica content. However, it does show that a range of lava compositions
(basalt, basaltic andesite, and andesite) have been erupted throughout the life of the
volcano.
33
1400
1200
1000
800
600
northwest
lateral vent
400
northeast
lateral vent
200
0
50
52
54
56
58
60
62
64
wt.% SiO2
Figure 5.4. Plot of vent height vs. wt. % SiO2.
65
157.5 ± 2.2 ka
60
wt. % SiO2
85.2 ± 3.1 ka
55
70.4 ± 6.1 ka
176.8 ± 6.1 ka
128.7 ± 22.2 ka
50
45
0 >150 ka
~150 to ~100 ka
~100 to ~60 ka
Figure 5.5: Plot of wt. % SiO2 versus age of the lava flow. Age axis is not to scale. Grey symbols
represent samples that have been radiometrically dated by 40Ar/39Ar with the determined ages
labeled.
34
18
5.3.
40
Ar/39Ar Age Dates
5.3.1. Phases of volcanism
The age dates at Maderas range from 176.8 ± 6.13 ka to 70.4 ± 6.1 ka and based on
geomorphology and location of the age dates it is suggested that the volcano experienced
at least three separate periods of volcanism. The first period occurred with the building
up of the original cone of the volcano prior to ~176 ka and lasting up to ~150 ka. This is
based on the two age dates (MADERAS-011 and MADERAS-003) obtained from the old
cone unit that can be seen on the geologic map (Figure 5.1).
The second period of volcanism occurred after ~150 ka but prior to ~100 ka. These lava
flows occur on the west, east, and northeast flanks of the volcano. They cover the old
cone and it is possible to trace their outline up the flanks of the volcano so it is believed
that they are younger than the old cone. This is supported by the age date obtained from
sample MADERAS-004 on the west side of the volcano with an age of ~128 ka (Figure
5.1). It is likely that they are older than the central graben as the graben constrained
volcanism to move north and south of the crater after it formed and these flows have not
been constrained in that manner. However, there is no evidence to show that they could
not have been erupted at the same time as the formation of the graben.
The third phase of volcanism occurred after ~100 ka and after the formation of the central
graben. The direction of the flows of this volcanism to the northwest and southeast was
controlled by the graben structure. The location of the flow with the youngest obtained
age date of ~70 ka lies outside of and near to the graben structure. This supports a
younger age as it shows that enough lava had accumulated within the graben for it to
have flowed over the side of the structure.
5.3.2. Implications of ages for shorelines at Maderas and Concepción
One difference between Maderas and Concepción volcanoes is the nature of their
shorelines. Maderas volcano exhibits a drowned shoreline whereas Concepcion’s
shorelines appear to be rising. At Concepcion the base of the volcano contains raised
beaches and deformed beds on its east and west sides (Borgia and van Wyk de Vries,
35
2003). The eastern side is characterized by diapiric rise while the western side is
characterized by outward thrusting (Borgia and van Wyk de Vries, 2003).
The difference in shorelines of the two volcanoes is likely due to the difference in ages
with Concepcion being younger than Maderas. Concepcion has historic activity (Diez et
al., 2006) as well as an age date of 19 ka (Siebert et al., 2010). At Concepcion the rise of
shorelines around its base is believed to be caused by loading of volcanic material which
causes spreading of the ductile lake sediments on which the volcano sits (Borgia and van
Wyk de Vries, 2003). The drowned shorelines of Maderas, which is no longer loading
volcanic material, imply that it is subsiding. This could be due to the reaction of the
underlying lake sediments to the overlying edifice over the last few tens of thousands of
years. The collapse of the magma chamber below the volcano is another possible
explanation for the apparent subsidence.
5.3.3. Comparison of age dates to other Central American volcanoes
The duration and age of volcanic front volcanoes in Central America is not yet well
constrained. Very few volcanoes have been extensively sampled for age dates. Figure 5.6
is a plot of dated age samples from various volcanoes in Central America. Most
volcanoes have numerous recent eruptions that have been dated but few older dates
making it difficult to study the duration of volcanism.
Carr et al. (2007b) show that onset of active volcanoes of the volcanic front in Nicaragua
is generally less than ~400 ka. This is based on the oldest Nicaraguan volcanic front lava
sample, from Telica volcano, that has an age of 330 ± 20 ka. Costa Rican volcanism is
thought to begin ~600 ka. In Nicaragua the age of onset of volcanism is much less
constrained due to the location of the volcanoes within the Nicaraguan depression and the
covering of the earliest flows of the volcanoes by sediments (Carr et al., 2007b).
Guatemalan volcanoes display similar ages. Extensive age-date sampling at Santa Maria
revealed ages ranging from 103 ka to 35 ka (Escobar-Wolf et al., 2010) with another
eruption occurring in 1902. Volcanism at the Fuego-Acatenango volcanic complex
36
ranges in age from over 230 ka to the present and with an age of less than 30 ka for
Fuego volcano itself (Vallance et al., 2001b).
Santa Maria
Fuego
Pacaya
Cosegüina
San Cristóbal
Telica
Cerro Negro
Momotombo
Concepción
Maderas
Rincón de la Vieja
Miravalles
Tenorio
Platanar
Poás
Barba
Irazu
Figure 5.6: Ranges of age dates analyzed for Central American volcanoes. White symbols represent
Guatemalan volcanoes, black symbol represent Nicaraguan volcanoes and grey symbols represent
Costa Rican volcanoes. (Age dates from (Bardintzeff and Deniel, 1992; Vallance et al., 2001b; Carr et
al., 2007b; Escobar-Wolf et al., 2010; Siebert et al., 2010)
In all of these cases it is difficult to know the duration of volcanism with only a few dated
samples. Most of Fuego’s young volcanism may have happened in the past 30 ka while it
is built on an edifice that is 230 ka or more (Vallance et al., 2001b). While Santa Maria is
mostly younger than 103 ka, it is built on cones that have ages ranging from 163-438 ka
(Singer et al., in press). Only a few volcanoes have more than a few dates, so the duration
of currently active cones is unconstrained and could be a few tens of thousands of years.
Do the maximum ages of cones like Telica suggest that the volcano is continuously active
for 300 ka or is the volcano’s current activity only the latest of several periods of
concentrated activity, each of which could be viewed as a separate volcano? For Maderas
itself are there two volcanoes or one? Does the lack of age-dated materials younger than
60ka mean that Maderas is extinct? The answers to these questions are unknown. But the
apparent lack of activity for 60 ka is surely significant to hazards potential and it
37
contrasts markedly with Concepción which is known to have had dangerous historic
activity.
5.4.
An eruptive history of Maderas
Based on the geochemical and age date results gathered in this study and on the geologic
map, a brief history of Maderas volcano has been outlined. It has been divided into 5
phases, each of which is discussed below.
1. Construction of the older cone: The initial activity of Maderas is buried under the
current edifice and cannot be described. Therefore, the first phase of the volcano
discussed here is the construction of the cone. Based on the ages shown in Table 4.2, this
older cone was formed more than ~150 ka. The volcano began to build up an edifice
composed of alternating lava flows and pyroclastic deposits. It is likely that the west side
of the volcano received more pyroclastic material, as seen at Concepción (Borgia and van
Wyk de Vries, 2003), as the prevailing trade wind direction is east to west and this is
likely to have been true throughout the life of the volcano. Traverses into some of the
deepest eroded channels on the volcano revealed both lava flows and pyroclastic
deposits. Mathieu (2010) describes some of these deposits. The locations of these deep
gullies can be found on the steepest slopes of the volcano, which, explained above, are
likely to be remnants of the original cone. It is likely that the older cone formerly reached
an elevation similar to that of Concepción (1600 m.a.s.l. compared to Maderas’ current
elevation of 1394 m.a.s.l.).
The reason for the steeper slopes on Maderas’ older cone is unknown. Continual erosion
over an extended period of time could result in the observed steeper slopes. Additionally,
the formation of the graben could have caused a slight upward tilting of the slopes
making them steeper (Figure 5.2). Another possibility could be the eruption of more
silicic material from higher up on the edifice which could result in a thick hard core to the
volcano and more resistant lava flows near the summit which would be slower to erode
and could cause steepening of the slopes of the underlying units. However, the
geochemical data does not support this as seen in Figure 5.4 where there is not a strong
38
correlation between vent height and more silicic lava composition. The most silicic rocks
found at Maderas were actually found near the base of the volcano. It is possible that
even though there is not a correlation between composition and vent elevation, there
could be a tendency for thicker and more erosionally resistant units near the central vent.
This could partly explain why erosion seems to enhance steepness.
2. Pre-graben volcanism: Due to the observed traces of lava flows over the old cone,
these flows are thought to have been emplaced after formation of the old cone between
~150 ka and ~100 ka based on obtained age dates. These flows can be seen on the
eastern, northeastern and western sides of Maderas. It is proposed that during this time
period lava flows on the northeast side of the volcano, one of which is from a lateral vent,
flowed out into the lake and reacted with lake water to form littoral maars creating the
point at Punta Gorda and a crater-like feature near the town of El Corozal Nuevo.
3. Faulting and formation of the graben: Maderas was affected by faulting in a general
NW-SE direction roughly parallel to the Nicaraguan depression and the CAVF. These
faults formed an asymmetrical graben through the center of the volcano with the eastern
fault having dropped down more than the western fault and leaving behind a larger fault
scarp. This graben caused the top of the volcano to become flattened and created an
asymmetrical shape to the profile of the volcano. The age of the formation of the graben
is not well constrained. It is thought to have started after or possibly concurrently with the
eruption of the pre-graben flows. The initial faulting of the graben is estimated to have
begun ~100 ka.
4. Post-graben volcanism and lateral vent on the northwest side of the volcano: After
the formation of the graben Maderas continued to erupt. It is thought that little or no
eruptive activity occurred during the formation of the graben as the faults do not appear
to have been covered up by eruptive material. The formation of the graben in the center
of the volcano created a topographic low and constrained the movement of lava along this
low, covering up the older, steeper parts of the cone that had been dropped down. One
flow, to the southeast of the volcano appears to have been strongly constrained by the
39
faulting and flowed down a channel-like feature. The age range of these lavas is
estimated at ~80 ka to ~60 ka.
An active vent was present on the northwest flanks of the volcano that erupted various
lava flows. Four of the six analyses from these flows are andesitic, one is basaltic
andesite and one is basalt. An age date for MADERAS-015, a lava flow from this vent,
would help us constrain the age of the vent. The graben that runs through the volcano
does not appear to cut through this lateral vent and, therefore, it is proposed that it was
erupted after the formation of the graben.
5. Alluvial deposits: Throughout the life of the volcano, deep gullies formed and the
slopes of the volcano were eroded. Volcanic sediments accumulated around the base of
the volcano in the form of lahars and fluvial deposits. These deposits are more prevalent
below the old cone. There is also an alluvial fan located at the base of a large gully on the
southeast side of the volcano.
5.5.
Implications for geologic hazards
5.5.1. History of geologic hazards
According to Bundschuh et al. (2007), Central America is one of the regions in the world
most prone to geology-related natural disasters due its tectonic setting and climate.
Nicaragua, located in the center of Central America has experienced all of the following
geology-related hazards in the past two decades: earthquakes (Lesage et al., 2007),
tsunamis (Molina, 1997; Fernández and Ortiz, 2007), landslides or lahars (Kerle et al.,
2003; Rodríguez, 2007), hurricanes (Kerle et al., 2003), and volcanic eruptions (Alvarado
et al., 2007). Freundt et al. (2006) also list a number of volcano-related hazards that have
occurred in Nicaragua.
As a small island located in Nicaragua, Ometepe is vulnerable to hazards in different
ways than the rest of the country. Pelling and Uitto (2001) list and describe a number of
intrinsic vulnerabilities related to small island developing states (SIDS). While Ometepe
is not its own nation, many of these vulnerabilities still apply. These vulnerabilities are
40
small size, insularity and remoteness, environmental factors, disaster mitigation
capability, demographic factors, and economic factors.
Small size relates to limited natural resources, land use competition, and other spatial
issues found on small islands. Insularity and remoteness relates to the higher costs of
importing or exporting goods to and from the island, time delays in receiving goods, and
possible reduced flow of information to the island. Environmental factors relate to
exposure from large shorelines and small interiors. Demographic factors relate to smaller
populations and therefore a smaller human resource base, populations located near
shores, possible rapid changes in populations, and single urban centers. Economic factors
relate to small economies, specialized products, and dependence on external finance.
(Pelling and Uitto, 2001). On Ometepe, tourism is a large part of the economy and
hazards on the island could greatly influence its numbers. For example, during the time
the author lived on the island, Concepción volcano experienced small explosions over the
week of Semana Santa, a time of celebration in Nicaragua when many tourists visit the
island. Due to these small eruptions of Concepción, tourism on the island greatly
decreased and many businesses suffered because of it. Therefore it can be seen that when
small islands are confronted with geologic-hazards they face many obstacles.
Ometepe itself has experienced and remains vulnerable to all of the geologic hazards
mentioned above. Concepción volcano has erupted frequently in the past century. Diez et
al. (2006) prepared a table showing reported historical eruptions of Concepción volcano.
While the most recent eruptions have all been VEI =1 or VEI=2, earlier accounts indicate
that more violent eruptions have occurred. The most vulnerable populations for volcanic
eruptions of Ometepe are those living near Concepción and especially those living on the
west side of the volcano as prevailing trade winds move in that direction and will carry
ash and other pyroclastic material that way. Maderas volcano, to the south of
Concepción, is not known to have erupted in historic times. Since debris from
Concepción is blown to the west it is also relatively safe to live around Maderas when
looking at volcanic hazards from Concepción.
41
The island has experienced and remains at risk for earthquakes as well. The location of
Ometepe along the CAVF and near the subduction zone of the Cocos plate moving
beneath the Caribbean plate means that it is located in a very seismically active region of
the world. Funk et al (2009) prepared a figure (Figure 2) showing the locations of
numerous earthquakes from 1995-2003 in Nicaragua. They do not include the magnitudes
of these earthquakes; however, it is possible to see that many earthquakes have occurred
near Ometepe. They also interpreted a fault along the border of the Nicaraguan
depression on the west side of Lake Nicaragua and another one to the south of Maderas
volcano within Lake Nicaragua. French et al (2010) discuss an Mw 5.3 fore shock and Mw
6.3 main shock that occurred in Lake Nicaragua near Maderas in 2005.
Also, this study, as well as others (van Wyk de Vries and Borgia, 1996; Mathieu et al.,
2011), show that Maderas itself is crossed with a number of faults. Wells and
Coppersmith (1994) plot the surface rupture lengths of faults against moment magnitudes
the results of which suggest that the faults that cut across Ometepe (with the longest
surface rupture length being about 5 km) would have been formed by earthquakes with
magnitudes of about M5.5 or smaller. It is likely that continued faulting of the volcano
would create earthquakes of similar magnitudes.
Landslides and lahars are also known to occur on the island. On September 27, 1996 a
lahar (Figure 2.1) destroyed the town of El Corozal on the northeast flanks of Maderas
volcano, killing six people, destroying 36 houses and causing the people of the town to be
moved to a new location (Smithsonian Institution, 1996). Other deposits around the
volcano also show that lahars and landslides have occurred in other areas as well. A
report on lahar hazards at Concepción volcano was published in 2001 (Vallance et al.,
2001a). A lahar hazard map from this paper shows that large areas around Concepción
are at risk from lahars.
While no tsunamis have been documented on Ometepe, they are still a threat to the island
and possible tsunami triggers in Lake Nicaragua have been identified such as the collapse
of Mombacho volcano on the northwest shore of lake Nicaragua (Freundt et al., 2007). A
42
collapse of either volcano on Ometepe would not only cause tsunami hazards for the
residents of Ometepe but for those living around the shores of Lake Nicaragua as well.
5.5.2. Implications for Future Hazards
The new age dates imply that the volcano has likely not been active for tens of thousands
of years with the youngest determined age date being 70.4 ± 6.1 ka. It also implies that
the volcano has remained relatively stable over the past 170 ka years in that it has not had
explosive behavior or collapsed. The stability of the volcano is supported by work from
van Wyk de Vries and Borgia (1996) who looked at a number of different ratios between
characteristic geometric parameters to measure stability, how high a volcano can grow
before the failure of the brittle substratum, the mode of deformation of the substratum,
the buoyancy response of the substratum, and rate of deformation. The results of these
ratios imply that Maderas has considerable potential for spreading and low explosive and
collapse hazards. The lack of hydrothermal activity on the volcano (van Wyk de Vries
and Borgia, 1996) also makes it more stable as hydrothermal activity has been linked
with volcanic collapse (Lopez and Williams, 1993; Reid et al., 2001).
The apparent lack of activity at Maderas for ~60 ka implies that the risk for a future
eruption is low, however, it cannot be completely ruled out. Santa Maria volcano in
Guatemala erupted in 1902 after a repose that may have lasted ~30 ka (Escobar-Wolf et
al., 2010). However, there are often signs of unrest before a volcano erupts, especially
after long reposes. Before the Santa Maria eruption there was a marked seismic warning
lasting for months (Anderson, 1908). It is also likely that precursive deformation or
increased seismicity associated with movement of magma below the volcano would be
detected by people around Maderas. While Maderas is not being closely monitored for
deformation, a seismic station is located on its southwest side and there are two other
seismic stations on the island near Concepción. These stations will help scientists monitor
seismic activity on the island and should be able to recognize increased seismicity if it
occurs.
43
Lahars and landslides remain a concern for the inhabitants living on the flanks of
Maderas. As seen in the geologic map (Figure 5.1) much of the base of the volcano is
covered in alluvial deposits. It is likely that some of these have been deposited in the
form of lahars during extreme rainfall events. Therefore, there is a continued risk in these
areas for more lahars to occur as climate change may bring about more extreme weather
events (McBean, 2004). The older cone is the most likely source of these deposits as they
are largely located downslope of the older cone.
The older cone is also the most likely source for landslides or small-scale collapses on the
volcano. The average gradient of the older cone is about 25° but some slopes have
inclines of up to 77° (Figure 5.3). These steeper slopes are more unstable than other areas
of the volcano. Failure of these slopes could result in landslides. A small-scale collapse
was observed on one of these very steep slopes at Maderas by the author in 2009. Areas
located downslope of these steeper slopes have a higher a risk of landslides than other
areas on the volcano.
The experiences of Casita volcano in Nicaragua, which collapsed in 1998 during
Hurricane Mitch and produced a deadly debris flow (Kerle and van Wyk de Vries, 2001)
and of Toliman volcano in Guatemala, which collapsed in 2005 during Hurricane Stan
(Sheridan et al., 2007), are examples of this type of hazard. They suggest the
investigation of possible hydrothermal alteration in the older cone might be useful, and
they also point to the trigger mechanism of heavy rainfall loading from tropical
hurricanes. On Maderas, van Wyk de Vries and Borgia (1996) found that there is a lack
of hydrothermal features on the volcano because their formation is hindered by the
underlying lake sediments that seal fractures caused by spreading and do not allow a
hydrothermal system to rise into the volcano. This lack of alteration should make
Maderas more stable and less prone to large collapses caused by extreme rainfall events.
Earthquakes also remain a concern for the communities on the volcano due to Maderas’
location along the CAVF and near the subduction zone of the Cocos plate beneath the
Caribbean plate. Continued spreading of the volcano could also lead to more seismic
events.
44
Disaster preparedness on the island was taking place during the author’s residence in
Mérida. Care, International began a project on the island working with communities on
disasters (http://www.care.org/careswork/projects/NIC170.asp). One of their main
focuses on the island is Concepción as it is an active volcano. However a number of
workshops were given in all communities and schools on the island about the types of
hazards that can occur in each community, what to do in an emergency and signs for
evacuation routes were put up. (For those living on the Maderas side of Ometepe, the
community of San Ramon was chosen as a safe zone in case of a large eruption from
Concepción.) Community leaders were used and committees for each community were
formed, creating a chain of command for what to do in case of an emergency. This is a
positive step toward disaster preparation on the island, and hopefully community
workshops and school activities will continue to be carried out after Care, International
leaves. The choice of San Ramon as a safe location is supported by this study, which
shows that volcanic hazards at Maderas are far less likely than at Concepción.
45
6. Future Work
Regarding hazards, seismic monitoring of Maderas volcano should continue. As stated
above, it is unlikely that Maderas will become active again after ~60 ka of inactivity,
however it is not impossible. A look at lahar hazards on Maderas should also be
conducted. A study by the U.S. Geological Survey has been completed for Concepción
volcano (Vallance et al., 2001a). While, Concepción is more prone to lahars than
Maderas, a study of lahars should also be done for Maderas volcano. It is the author’s
understanding that a map of landslide/lahar hazards for Maderas is currently being
conducted by INETER.
Regarding INETER, an important aspect of this study will be to impart the information
gained to INETER. Collaboration is important among scientists, and it is especially
important to work with scientists in countries with fewer resources. It would also be
important to pass this information along to local tour guides who often state that the last
eruption at Maderas was ~800 to 1000 years ago. The author was unable to determine
where this date came from when talking to local tour guides
Finally community outreach programs should continue each year in all of the
communities of Ometepe regarding geologic hazards. It is important to remind the
inhabitants of the risks posed by the volcanoes and to discuss evacuation routes and what
to do in case a natural disaster occurs.
47
7. Conclusions
The main conclusions of the study are that Maderas volcano is similar to other Central
American volcanoes in regard to petrology, geochemistry, and age. Maderas is a typical
volcanic front volcano with lava compositions ranging from basalt to trachydacite. The
ages determined in this study for Maderas suggest that the volcano has not erupted for ~
60 ka.
The ages also indicate that Maderas underwent at least three phases of volcanism: the
construction of the initial cone prior to ~150 ka, pre-graben volcanism prior to ~100ka
and post-graben volcanism that occurred between ~100ka and ~60 ka. These phases are
separated by the formation of a central graben through the volcano that constrained the
movement of the last phase of volcanism within its boundaries.
These findings indicate that volcanic eruptions are not considered a likely hazard for
Maderas volcano. However, earthquakes and lahars are considered as significant hazards
that could occur. Tropical storms, especially those with high rainfall rates could lead to
dangerous debris flows beneath Maderas’ steep flanks. Continued seismic monitoring
should take place on the island as well as continued community outreach and education
about possible disasters, emergency plans, and evacuation routes.
49
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56
1.71
0.42
0.00
K2O
P2O5
H2O+
99.01
3.28
Na2O
0.059
8.53
CaO
Total %
3.34
MgO
Sr
0.17
MnO
-0.51
9.21
Fe2O3
0.054
18.45
Al2O3
Ba
0.97
H2O-
53.33
TiO2
Maderas001
SiO2
Sample
Name
100.00
0.061
0.060
-0.77
0.26
0.39
1.96
3.79
8.04
2.92
0.17
9.84
18.95
1.01
53.30
Maderas002
99.50
0.031
0.086
0.00
1.00
0.32
3.62
4.38
2.91
1.11
0.16
8.44
15.26
0.96
61.23
Maderas003
99.49
0.050
0.033
-0.64
0.29
0.26
1.03
2.26
10.48
5.36
0.19
12.42
17.17
1.07
49.51
Maderas004
99.40
0.052
0.072
-0.03
0.26
0.59
2.18
3.92
6.33
2.42
0.20
9.81
17.00
1.18
55.42
Maderas005
99.80
0.052
0.063
-0.08
0.26
0.38
2.44
3.39
7.14
3.41
0.16
8.78
16.99
0.90
55.91
Maderas006
99.86
0.037
0.073
-0.01
0.21
0.22
3.37
5.33
3.50
1.30
0.20
7.13
16.12
0.94
61.43
Maderas007
100.37
0.057
0.041
-0.05
0.21
0.34
1.17
3.00
9.43
4.48
0.19
11.72
18.40
1.15
50.22
Maderas008
99.35
0.044
0.066
0.82
0.45
0.43
2.74
3.82
4.80
2.22
0.14
7.43
17.36
0.90
58.12
Maderas009
99.83
0.051
0.044
-0.65
0.16
0.37
1.81
3.38
8.58
2.30
0.15
10.12
19.46
1.02
53.02
Maderas011
99.47
0.052
0.037
-0.27
0.21
0.39
1.63
3.31
9.07
3.74
0.17
10.14
18.17
1.08
51.74
Maderas012
Table 9.1: Whole-rock chemical analysis for samples collected during this study. All values are in wt. %. All Fe as Fe2O3.
9.1 Appendix A: Geochemical Data
9 Appendices
57
99.47
0.043
0.065
0.86
0.46
0.40
3.01
3.92
4.58
2.31
0.16
7.69
17.38
0.97
57.62
Maderas013
58
0.99
17.30
2.33
4.99
1.10
19.77
10.25
0.17
3.11
9.77
2.71
1.22
0.33
0.12
0.03
0.043
0.052
99.70
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
H2O+
H2O-
Ba
Sr
Total %
99.68
0.044
0.056
0.28
0.10
0.32
2.92
4.05
0.18
7.99
58.13
51.03
SiO2
Maderas015
Maderas014
Sample
Name
99.19
0.045
0.059
0.15
0.14
0.36
2.91
4.40
5.33
2.11
0.17
7.28
17.95
0.93
57.37
Maderas016
99.30
0.051
0.040
-0.23
0.11
0.32
1.34
2.89
9.84
3.07
0.16
10.38
19.30
1.07
50.96
Maderas017
99.27
0.045
0.049
0.06
0.18
0.42
2.23
7.53
6.57
2.88
0.21
9.01
16.42
1.09
52.58
Maderas018
99.75
0.045
0.049
-0.05
0.15
0.61
3.10
4.13
4.92
1.96
0.19
8.18
16.27
1.11
59.07
Maderas020
Table 9.1: Continued.
99.61
0.062
0.027
-0.28
0.17
0.39
1.26
2.79
10.24
3.98
0.17
10.73
19.01
1.15
49.91
Maderas021
100.04
0.059
0.037
-0.15
0.39
0.54
2.07
3.36
7.96
2.48
0.19
10.19
18.39
1.20
53.34
11-A
99.43
0.059
0.023
0.61
1.42
0.44
1.16
2.42
9.97
4.57
0.16
11.40
16.69
1.17
49.34
14 C
99.58
0.051
0.048
-0.36
0.28
0.36
1.88
3.18
8.61
2.27
0.14
9.24
19.29
1.03
53.56
17
99.14
0.055
0.073
-0.16
0.26
0.63
2.35
4.18
6.26
2.08
0.18
8.89
17.49
1.19
55.66
26 B
99.96
0.044
0.090
0.23
0.45
0.45
2.24
3.75
6.04
2.85
0.17
10.65
17.27
1.10
54.62
39
97.27
0.039
0.063
-0.45
0.31
0.62
2.53
3.56
5.27
2.21
0.17
11.16
15.37
1.23
55.20
41
M1
1.07
16.46
6.81
0.17
1.91
4.56
4.29
2.83
0.46
15.74
77.94
2.12
9.11
0.54
20.1
82.23
66.65
431.69
36.34
299.98
29.66
1.59
0.76
1160
4.02
1.42
0.72
5.6
8.44
5.86
3.53
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
Sc
V
Cr
Co
Ni
Cu
Zn
Rb
Sr
Y
Zr
Nb
Mo
Cs
Ba
Hf
Ta
W
Tl
Pb
Th
U
60.75
SiO2
Sample
3.66
5.64
5.6
5.53
0.89
1.54
4.21
1200
0.82
2.63
29.69
314.27
43.71
416.37
57.68
84.37
22.36
0.3
10.22
1.6
85.36
17.13
0.44
2.8
4.34
4.4
1.95
0.17
7.26
17.32
1.09
61.74
M2
1.41
2.33
2.27
1.54
0.28
0.59
1.92
624
0.27
1.1
12.85
144.03
21.87
561.03
15.6
79.74
137.25
14.9
29.77
26.01
307.22
30.79
0.32
1.07
2.76
9.54
4.56
0.18
10.03
18.66
1.1
50.37
M3
1.38
2.02
2.47
1.98
0.29
0.6
1.75
586
0.24
1.02
12.36
125.57
21.22
530.19
23.88
77.02
95.3
11.9
27.16
26.17
292.56
28.46
0.3
1.22
2.84
9.3
4.18
0.17
9.79
18.29
1.07
51.73
M4
1.3
1.95
2.51
2.29
0.29
0.54
1.65
538
0.45
1.06
11.67
118
19
511.27
21.95
67.91
108
11.46
24.78
23.11
260.76
24.01
0.3
1.15
2.69
9.52
4.49
0.17
9.81
18.39
1.07
50.69
M5
1.43
2.07
2.42
2.47
0.3
0.59
1.66
536
0.48
1.01
11.84
119.92
18.47
504.01
22.55
72.76
107.23
13
24.78
24.12
270
25.92
0.3
1.15
2.69
9.52
4.49
0.17
9.81
18.39
1.07
50.69
M5dup
1.21
1.86
2.53
2.54
0.27
0.59
1.63
562
0.45
1.05
11.21
117.99
19.03
497.51
22.57
75.28
128.9
12.52
26.78
23.63
274.65
26.38
0.31
1.21
2.62
9.53
4.51
0.17
9.97
18.26
1.07
51.22
M6
1.18
1.9
2.47
2.92
0.29
0.55
1.6
550
0.51
0.99
11.4
118.18
19.64
499.01
25.01
69.61
125.73
12.58
26.89
23.54
261.13
26.5
0.3
1.33
2.49
9.63
4.54
0.17
9.69
18.41
1.04
50.79
M7
1.23
1.8
2.54
3.16
0.28
0.56
1.66
521
0.5
1.04
11.06
118.94
16.72
444.01
20.32
74.05
110.05
15.14
27.05
23.36
290.99
24.99
0.27
1.22
2.38
9.48
4.76
0.17
9.82
18.06
0.99
51.56
M8
1.63
2.48
2.82
3.45
0.32
0.6
1.83
549
0.54
1.1
11.7
119.72
18.21
448.53
22.02
67.3
96.91
13.13
23.54
19.43
233.95
25.21
0.27
1.22
2.38
9.48
4.76
0.17
9.82
18.06
0.99
51.56
M8a
1.55
2.38
3.32
3.44
0.33
0.65
1.74
551
0.58
1.17
11.75
121.21
19.02
484.54
25.97
76.58
128.45
16.31
27.64
23.5
282.93
28.77
0.27
1.17
2.48
9.65
4.68
0.17
9.67
18.22
0.98
51.2
M9
1.38
2.11
2.75
3.48
0.3
0.57
1.69
544
0.57
1.11
11.6
120.68
18.5
494
25.65
72.88
122.59
14.71
28.08
22.91
273.38
27.97
0.27
1.17
2.48
9.65
4.68
0.17
9.67
18.22
0.98
51.2
M9S0
2.08
3.16
3.78
5.08
0.41
0.8
2.27
759
0.87
1.59
15.81
176.78
22.81
484.98
37.25
71.44
98.76
10.74
21.66
12.23
210.24
24.32
0.13
0.43
2.35
10.13
4.16
0.15
8.28
20.8
0.56
51.7
M10
1.3
1.86
2.57
2.15
0.23
0.47
1.62
471
0.48
0.94
9.46
119.14
18.23
429.25
20.4
68.21
135.76
27.81
30.79
50.44
243.95
26.35
0.23
1.21
2.56
10.65
5.82
0.15
9.36
17.78
0.88
50.21
M11
1.45
2.09
2.74
2.05
0.26
0.47
1.66
487
0.44
0.91
9.16
109.83
17.43
424.84
17.97
58.95
119.45
22.44
25.9
41.89
212.44
21.88
0.23
1.21
2.56
10.65
5.82
0.15
9.36
17.78
0.88
50.21
M11a
1.07
1.85
2.1
0.98
0.23
0.59
1.7
503
0.15
0.92
13.06
123.06
19.98
543.3
18.64
80.33
149.06
19.68
34.61
10.99
322.24
29.24
0.3
0.96
2.25
10.85
5.29
0.17
10.8
18.65
1.18
48.12
M12
Table 9.2: Geochemical information from Maderas volcano (Lindsay 2009). Element oxides are in wt. % and elements are in ppm. All Fe as Fe2O3.
59
60
8.64
35.86
7.63
1.95
7.09
1.03
5.84
1.21
3.91
0.54.
3.42
Pr
Nd
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
0.56
73.71
Ce
Lu
35.97
M1
La
Sample
0.61
3.87
0.63
4.11
1.46
6.95
1.23
8.54
2.11
9.4
47.1
10.28
75.13
48.3
M2
0.34
2.21
0.32
2.34
0.8
3.94
0.7
4.78
1.43
5.04
24.36
5.22
38.56
19.04
M3
0.3
2.07
0.32
2.31
0.73
3.74
0.68
4.74
1.47
4.72
22.52
5.06
35.13
18.14
M4
0.28
1.86
0.3
1.96
0.74
3.31
0.62
4.19
1.24
4.26
19.7
4.16
33.23
15.98
M5
0.29
2.03
0.31
2.07
0.7
3.44
0.61
4.03
1.26
4.24
19.97
4.24
33.88
16.42
M5
dup
0.27
1.93
0.29
2.07
0.73
3.55
0.6
4.27
1.24
4.43
19.05
4.44
34.7
16.54
M6
0.29
1.99
0.3
2.1
0.69
3.56
0.65
4.28
1.28
4.15
19.11
4.37
34.33
16.7
M7
0.27
1.83
0.28
1.87
0.65
3.34
0.6
3.84
1.15
3.87
17.78
4.04
31.78
15.52
M8
0.3
2.13
0.32
2.14
0.71
3.62
0.65
4.12
1.28
4.23
20.01
4.68
34.5
17.55
M8a
0.31
2.06
0.31
2.15
0.72
3.6
0.66
4.26
1.3
4.42
19.72
4.57
35.18
17.08
M9
0.29
2.01
0.3
2.14
0.67
3.46
0.63
4.14
1.25
4.15
20.23
4.49
35.34
17
M9S0
0.35
2.36
0.37
2.45
0.84
4
0.74
5.07
1.45
5.45
26.89
5.61
45.15
23.17
M10
0.27
1.95
0.29
1.95
0.64
3.24
0.59
3.78
1.13
4.1
17.69
3.89
28.56
14.35
M11
0.28
2.01
0.3
1.95
0.68
3.36
0.6
4
1.08
3.84
17.57
4.05
29.34
14.23
M11a
Table 9.3: Rare earth element analyses of Maderas volcano from Lindsay (2009). Elements are in ppm.
M12
0.29
1.86
0.3
2.22
0.74
3.69
0.63
4.57
1.28
4.51
20.72
4.51
34.58
16.81
M1
52.02
1.01
19.19
9.32
0.17
4.31
9.71
3.1
1.14
0.24
252
210
30
16
136
81
17
22
515
21
131
11.4
3
918
5
4
5
Sample
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
V
Cr
Co
Ni
Cu
Zn
Ga
Rb
Sr
Y
Zr
Nb
Mo
Ba
Pb
Th
U
5
55
53
21
13
13
79
18
88
360
100
386
33
3
1706
12
11
63.32
0.88
16.97
5.26
0.13
1
3.51
4.3
3.5
0.29
M2
5
78
51
22
13
14
84
15
87
355
91
386
34
3
1750
10
10
62.98
0.87
16.88
5.19
0.12
1.1
3.42
4.43
3.49
0.27
M2A
5
125
56
24
14
16
90
19
68
440
46
306
26.2
3
1759
10
9
60.23
1.13
16.97
7.14
0.19
1.85
4.94
4.4
2.82
0.53
M3
5
63
53
21
13
14
85
16
88
350
51
393
34.8
4
1913
14
12
63.15
0.09
16.78
5.31
0.16
0.1
3.52
4.86
3.73
0.31
M4
6
214
127
28
15
64
75
19
45
603
39
261
23.4
4
1412
5
4
52.87
1.4
19.35
8.96
0.16
2.66
8.88
3.62
2.02
0.52
M5
5
246
202
30
16
113
65
16
30
508
25
157
14.9
4
942
6
6
50.36
1.11
17.77
10.52
0.18
5.53
10.44
2.93
1.27
0.3
M6
5
123
58
25
14
44
74
19
53
546
31
246
22.4
3
1150
6
6
57.01
0.97
18.7
7.1
0.15
2.07
7
3.86
2.33
0.44
M7
5
127
108
24
14
49
70
17
52
537
32
234
21.8
4
1523
9
4
57.34
0.96
19.08
6.86
0.15
2.11
7.03
3.97
2.22
0.41
M8
5
210
305
29
16
89
89
17
31
524
32
209
20.9
4
1141
5
5
52.69
1.4
18.28
9.8
0.17
3.91
9.39
3.28
1.57
0.39
M9
6
173
181
29
16
59
74
19
41
498
28
184
16.3
4
1375
10
4
54.11
1.03
18.34
8.32
0.16
3.82
8.72
3.31
1.83
0.38
M10
5
252
336
30
16
107
85
12
30
494
24
175
19.7
4
989
5
4
50.56
1.2
16.61
9.77
0.17
5.28
10.05
2.47
1.45
0.32
M11
3
233
75
41
17
121
89
19
37
482
38
207
17.3
2
1297
6
4
51.7
1.07
18.22
10.05
0.18
4.08
8.41
2.68
1.6
0.32
M13X
5
122
57
26
14
49
77
17
56
435
50
274
25.4
3
1504
8
7
57.46
1.15
17.03
7.83
0.2
2.46
5.83
3.96
2.51
0.44
M14
5
129
59
25
14
57
70
16
61
482
30
260
22.5
4
1459
9
8
57.22
0.93
17.22
7.64
0.17
3.27
6.94
3.45
2.72
0.35
M15
5
151
81
25
14
66
68
17
63
470
34
265
24.2
3
1560
8
6
57.79
0.91
16.94
7.26
0.16
2.64
6.32
3.55
2.63
0.35
M16
5
152
58
27
15
58
98
20
51
509
41
253
23.7
4
1551
11
5
56.25
1.18
16.98
8.24
0.2
2.36
6.24
3.93
2.37
0.55
M17
5
79
56
25
14
20
101
19
54
503
43
283
28.5
3
1557
10
7
59.23
1.13
17.52
7.11
0.19
1.87
5.29
5.27
2.56
0.57
M18
Table 9.4: Whole rock and trace element analyses of Maderas volcano from van Wyk de Vries (unpublished). Element oxides are in wt. %. Elements
are in ppm. All Fe as Fe2O3.
61
CL1
59.48
0.91
17.42
6.68
0.18
2.57
5.49
4.84
2.10
0.44
0.60
93
54
25
14
27
94
21
5
48
461
39
206
16
3
1488
9
4
5
Sample
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
LOI
V
Cr
Co
Ni
Cu
Zn
Ga
As
Rb
Sr
Y
Zr
Nb
Mo
Ba
Pb
Th
U
5
75
56
25
14
34
95
18
5
48
455
40
207
17
3
1533
12
5
59.25
0.94
17.09
6.77
0.18
2.52
5.47
4.70
2.12
0.46
0.02
CL2
5
199
106
28
15
104
89
19
5
36
597
27
147
11
3
1402
6
4
53.21
0.96
19.12
7.90
0.16
3.24
8.58
3.96
1.52
0.28
0.04
CL3
5
183
187
28
15
84
89
19
6
34
589
28
147
12
3
982
6
4
53.91
0.99
19.00
7.92
0.17
3.37
8.49
3.57
1.50
0.37
0.11
CL4
48.05
1.25
20.57
10.32
0.18
3.42
9.17
3.07
0.79
0.47
2.37
CL5
6
174
88
29
15
83
85
17
5
31
539
33
144
12
3
889
5
4
53.52
1.11
18.67
9.15
0.20
3.35
7.98
4.28
1.44
0.38
0.01
CL6
5
184
131
28
15
76
85
17
5
26
570
27
135
11
3
1188
10
4
52.94
1.02
19.48
8.36
0.17
3.15
8.90
3.82
1.29
0.31
0.07
CL7
5
199
98
28
15
41
78
18
5
23
571
27
122
10
3
1416
5
4
52.52
0.99
18.93
8.65
0.19
3.79
8.78
4.06
1.21
0.42
0.19
CL8
5
98
55
24
14
25
81
21
5
46
458
36
214
17
3
1640
9
5
60.62
0.80
17.19
5.93
0.16
2.14
5.49
4.43
2.15
0.37
0.12
CL9
5
145
56
25
14
37
94
14
5
46
458
69
204
15
3
1452
8
4
59.41
0.92
17.17
6.77
0.19
2.48
5.51
5.13
2.10
0.44
0.09
CL10
5
98
56
24
13
24
82
17
5
47
457
34
205
17
3
1523
8
5
61.26
0.85
17.38
6.10
0.17
2.17
5.67
4.02
2.11
0.35
0.09
CL11
5
102
57
25
14
33
96
18
6
49
471
41
217
17
3
1463
9
5
56.69
0.89
16.95
6.94
0.19
2.27
5.40
4.80
2.18
0.48
0.18
CL13
5
95
56
24
13
21
88
18
5
48
454
37
208
16
4
1433
13
5
60.65
0.93
17.26
6.29
0.18
2.34
5.44
4.63
2.13
0.45
0.01
CL14
6
167
62
27
14
47
82
19
5
27
627
28
135
11
3
1254
7
4
54.55
0.95
19.07
7.58
0.17
2.92
8.36
4.11
1.31
0.42
-0.14
CL15
5
179
117
27
15
60
80
20
5
23
623
25
119
10
4
924
7
4
54.39
0.93
19.72
7.71
0.17
2.64
8.56
3.96
1.16
0.37
0.02
CL16
Table 9.5: Whole rock and trace element data for Concepción volcano from van Wyk de Vries (1993). Oxides are in wt. %. Trace elements are in ppm.
All Fe as Fe2O3.
62
63
CL17
56.01
1.02
18.85
7.68
0.17
2.44
8.05
4.02
1.61
0.43
0.25
141
121
27
15
72
77
19
6
34
575
31
167
14
3
1160
6
4
5
Sample
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
LOI
V
Cr
Co
Ni
Cu
Zn
Ga
As
Rb
Sr
Y
Zr
Nb
Mo
Ba
Pb
Th
U
97
55
24
14
18
86
19
5
54
452
43
236
18
5
1588
10
4
5
61.59
0.83
16.75
6.11
0.18
1.79
4.57
5.11
2.45
0.47
0.17
CL19
77
56
24
14
17
96
18
5
57
451
42
234
18
3
1586
7
5
5
62.02
0.87
16.62
6.12
0.18
1.97
4.57
4.76
2.42
0.42
0.22
CL20
50
55
23
13
10
89
20
5
44
456
38
202
17
5
1823
12
6
5
61.53
0.84
16.84
5.45
0.17
2.29
4.75
5.31
1.99
0.41
0.14
CL21
146
167
27
14
67
88
17
5
26
606
28
134
11
3
1272
6
4
5
54.87
0.99
19.38
7.72
0.17
2.89
8.41
4.16
1.36
0.40
0.02
CL23
230
148
28
15
92
86
20
6
35
585
26
150
12
3
1527
11
4
6
53.57
0.97
18.77
7.91
0.18
3.37
8.62
4.38
1.55
0.39
0.20
CL25A
230
148
28
15
92
86
20
6
35
585
26
150
12
3
1527
11
4
6
53.95
0.98
18.90
7.97
0.18
3.39
8.68
4.41
1.56
0.39
0.08
CL25A
128
129
27
14
61
88
16
5
33
578
31
167
13
3
1475
5
4
5
56.54
0.99
18.94
7.26
0.18
2.69
7.66
4.03
1.55
0.37
0.38
CL25
Table 9.5: Continued.
173
97
28
15
106
82
19
6
34
631
29
149
12
3
1078
7
4
6
54.64
0.93
19.06
8.05
0.16
2.72
8.47
3.79
1.67
0.39
0.22
CL26
145
59
33
8
25
81
18
4
32
537
32
161
14
3
1206
6
2
3
58.66
0.92
16.93
7.68
0.18
2.10
6.47
4.14
1.73
0.39
0.70
CL27
98
54
29
7
8
83
20
4
45
490
39
213
18
3
1328
11
4
3
62.87
0.83
16.84
5.64
0.18
1.72
4.57
4.72
2.15
0.29
0.13
CL28
253
100
42
13
112
94
21
5
26
663
29
130
12
2
708
5
3
3
52.03
1.25
19.36
9.79
0.19
3.75
9.53
2.79
1.04
0.22
0.37
CL29A
286
169
43
13
189
99
18
5
23
544
24
88
8
3
751
5
3
3
52.02
1.14
19.50
9.96
0.18
3.87
9.59
2.87
1.05
0.35
0.50
CL29B
264
74
42
13
110
98
21
5
23
644
27
124
11
3
876
8
3
3
51.68
1.13
19.30
9.82
0.18
3.94
9.50
2.68
1.00
0.34
0.44
CL30
127
58
34
9
35
83
21
4
37
550
38
201
18
3
1372
6
4
3
57.74
0.97
19.96
8.11
0.18
2.18
6.56
4.20
1.97
0.43
0.21
CL31
64
0.61
79
56
29
LOI
V
Cr
Co
4
51
475
38
217
18
3
1362
9
5
3
As
Rb
Sr
Y
Zr
Nb
Mo
Ba
Pb
Th
U
17
0.29
P2O5
91
2.27
K2O
Zn
4.59
Na2O
Ga
4.40
CaO
7
1.75
MgO
16
0.18
MnO
Ni
175
5.96
Fe2O3
Cu
0.15
16.36
Al2O3
3
2
8
934
2
14
144
28
750
30
4
22
79
95
9
37
62
0.38
1.56
3.37
8.85
2.45
0.17
8.98
19.43
1.03
0.86
53.18
63.10
CL35
TiO2
CL33
SiO2
Sample
3
3
7
916
3
14
140
27
738
32
4
21
78
59
11
35
62
161
0.21
0.46
1.65
3.66
8.92
2.42
0.16
8.37
19.38
0.96
53.72
CL36
0.29
0.42
1.36
3.24
9.20
3.13
0.15
8.49
19.97
1.03
51.02
CL37A
-0.22
0.37
0.95
3.24
9.51
4.54
0.20
10.91
18.23
1.22
51.16
CL38
3
2
6
715
3
7
74
17
690
10
4
18
76
133
13
40
134
225
1.20
0.08
0.47
1.90
12.22
3.52
0.15
10.26
21.42
0.89
47.86
CL39
3
2
5
462
3
7
72
18
654
10
4
17
77
117
22
40
131
211
0.93
0.04
0.54
2.01
12.71
3.77
0.16
9.75
21.34
0.90
48.27
CL40
Table 9.5: Continued.
3
2
5
717
3
7
71
17
662
11
4
18
74
122
12
40
161
242
0.35
0.07
0.57
2.22
12.37
3.92
0.15
10.11
20.91
0.89
47.93
CL42
3
3
5
611
3
8
71
18
681
12
4
22
71
126
13
40
144
254
0.01
0.14
0.58
2.30
12.38
3.75
0.15
10.40
20.63
0.83
47.34
CL41
3
2
8
595
3
9
108
23
689
20
4
19
77
88
9
37
84
185
0.55
0.17
0.97
2.85
10.06
2.90
0.15
9.24
20.39
0.92
51.35
CL43
3
3
8
1239
3
15
170
30
595
32
4
20
84
107
11
37
62
269
0.01
0.41
1.63
4.05
7.77
2.67
0.17
9.03
17.12
1.11
55.59
CL44
872
19
13
0.51
0.41
1.47
3.37
8.32
3.87
0.18
9.23
18.29
1.07
53.52
CL45
65
1.31
0.64
3.05
30.00
U
Ta
Hf
Rb
10.00
2.27
Th
Cr
0.41
Lu
25.30
2.40
Yb
Sc
0.79
Tb
0.53
1.71
Eu
22.80
5.80
Sm
Co
26.30
Nd
Cs
44.10
Ce
CL7
21.40
La
Sample Name
5.00
16.40
11.30
1.04
52.00
4.82
0.97
2.59
3.89
0.54
3.22
1.00
1.89
7.37
34.10
59.10
29.50
CL11
11.00
22.10
19.20
0.78
38.00
3.32
0.59
1.74
2.51
0.41
2.41
0.82
1.82
6.47
29.10
47.70
23.20
CL26
14.00
27.90
26.10
0.63
29.00
2.65
0.47
1.21
1.87
0.38
2.23
0.76
1.72
5.63
24.10
37.40
18.60
CL29A
27.70
26.20
0.80
1.71
0.33
0.83
0.87
0.29
1.97
0.68
1.17
3.76
15.50
22.60
9.70
CL29B
6.00
18.80
15.60
0.36
46.00
4.49
0.95
1.97
3.05
0.55
3.34
1.08
2.12
8.01
35.80
60.50
29.10
CL31
13.00
21.70
20.20
0.39
33.00
3.00
0.66
1.71
2.44
0.37
2.22
0.78
1.84
6.31
29.10
50.30
25.70
CL36
Table 9.6: Rare earth elements at Concepción volcano from van Wyk de Vries (1993). Elements are in ppm.
C1
55.78
1
17.63
9.03
9.03
0.2
3.31
7.73
4.11
1.22
0.38
19.88
165.13
2.54
17.45
2.49
51.08
81.04
23.19
547.48
25.46
122.19
11.11
1.02
0.34
657.21
Sample
SiO2
TiO2
Al2O3
Fe2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
Sc
V
Cr
Co
Ni
Cu
Zn
Rb
Sr
Y
Zr
Nb
Mo
Cs
Ba
19.03
174.51
2.43
18.45
2.42
47.87
88.27
20.34
572.52
24.63
127.26
11.76
1.1
0.44
674.18
55.43
0.98
17.92
8.68
8.68
0.2
3.28
7.71
3.74
1.2
0.37
C2
19.77
183.96
2.92
17.26
1.91
96.85
87.43
34.99
450.12
29.67
184.94
15.18
1.67
0.82
973.89
56.77
1.1
16.95
8.57
8.57
0.18
2.7
6.49
3.49
1.94
0.49
C3
27.21
229.5
15.59
12.34
91.07
26.5
577.9
28.99
136.2
10.3
0.69
789.4
12.04
32.63
35.5
607.3
40.21
159.1
10.7
0.822
986.6
51.9
1.13
19.03
3.85
9.81
0.16
3.94
9.02
2.88
1.2
0.37
N148
20.43
130.4
15.96
55.96
1.14
17.66
2.25
8.62
0.17
2.9
6.88
4.06
1.65
0.58
N146
990.3
119.8
37.5
589.1
18.6
84.4
23.51
237
20.4
8.89
0.17
3.72
7.11
3.17
1.7
0.23
58.75
0.71
16.58
C-92-2
31
783
20
72
16
49.09
1.319
18.52
11.1
11.1
0.24
5.64
11.09
2.99
0.64
0.104
C2
51
425
30
243
4
65.71
0.478
16.29
3.87
3.87
0.18
1.11
3.12
5.04
2.6
0.185
C1b
58
463
43
241
3
61.71
0.873
16.6
6.35
6.35
0.18
1.88
4.46
4.79
2.54
0.411
C5a
32
616
31
153
7
52.78
0.999
20.05
8.88
8.88
0.17
2.83
8.4
2.98
1.46
0.394
C7a
26
611
28
123
13
54.61
0.895
17.71
8.83
8.83
0.201
3.97
8.43
3.54
1.33
3.66
C1b
13
730
17
65
11
48.7
1.021
21.67
9.31
9.31
0.151
3.89
12.41
2.53
0.57
0.292
GAB1
Table 9.7: Whole rock and trace element analyses from Concepción volcano from Borgia and van Wyk de Vries (2003) and from Carr and Rose (1987).
Element oxides are in wt. % and elements are in ppm. All Fe as Fe2O3.
66
67
17.89
37.34
5.13
24.05
5.32
1.66
5.23
0.79
4.51
0.92
2.64
0.39
2.63
0.39
1.8
0.55
0.23
0.08
2.87
1.8
1.13
Ce
Pr
Nd
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Hf
Ta
W
Tl
Pb
Th
U
C1
La
Sample
1.15
1.87
2.7
0.09
0.21
0.58
1.75
0.38
2.5
0.39
2.65
0.91
4.38
0.78
5.33
1.67
5.27
24.09
5.14
39.14
18.42
C2
1.87
3.08
4.16
0.17
0.36
0.77
2.5
0.46
3.18
0.47
3.06
1.08
5.01
0.95
6.34
1.87
6.44
29.48
6.92
53.41
25.95
C3
1.835
2.482
4.479
3.69
3.57
6.45
7.56
2.26
7.35
34.83
56.17
27.04
N146
1.497
2.158
3.98
2.33
2.69
5.14
5.71
1.69
5.73
26.45
44.68
22.05
N148
Table 9.8: Rare earth element analysis from Concepción volcano from Carr and Rose (1987).
1.357000
0.004985
Σ
38Ar(cl)
0.1466
40(r)/39(k)
± 0.0126
± 8.62%
0.1418
± 0.0149
± 10.51%
Minimal External Error
Analytical Error
Total Fusion
Age
Age
68.1
70.4
± 75.9
± 117.5
± 152.4
± 22.1
± 10.8
± 10.0
± 16.8
± 24.4
± 31.8
± 2σ
(Ka)
± 7.6
± 7.2
± 7.2
± 10.51%
± 6.7
± 6.1
± 6.1
± 8.62%
± 2σ
(Ka)
28.5
50.4
49.8
65.6
73.6
72.5
65.1
66.1
66.4
Age
0.191027
0.001684
0.002089
0.001848
0.014828
0.052217
0.047540
0.030329
0.025572
0.014919
40Ar(r)
± 2σ
Minimal External Error
Analytical Error
Age Plateau
1.346837
0.028409
0.019890
0.017814
0.108512
0.340424
0.314617
0.223659
0.185675
0.107837
39Ar(k)
Table 9.9: Continued
0.000855
0.000011
0.000000
0.000000
0.000000
0.000000
0.000080
0.000104
0.000259
0.000400
Results
0.029115
0.018225
0.015139
0.093700
0.267650
0.221664
0.227012
0.187692
0.296803
0.000172
0.000073
0.000047
0.000251
0.000626
0.000568
0.000905
0.000909
0.001435
37Ar(ca)









Information
on Analysis
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
36Ar(a)
Sample = MAD002
Material = groundmass
Location = UW93C42
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
Incremental
Heating
3.20
8.85
11.66
16.67
22.01
22.09
10.19
8.69
3.40
40Ar(r)
(%)
Table 9.9: Incremental heating summary for MADERAS-002
2.31
1.0000
0.34
MSW
D
9.2.1 Sample MADERAS-002
9.2 Appendix B: 40Ar/39Ar Results
68
0.293
K/Ca
0.420
0.469
0.506
0.498
0.547
0.610
0.424
0.425
0.156
K/Ca
9
0.427
± 2σ
± 0.114
± 2σ
± 0.024
± 0.030
± 0.033
± 0.027
± 0.028
± 0.031
± 0.022
± 0.022
± 0.008
± 0.009
Statistical T Ratio
Error Magnification
100.00
9
39Ar(k)
(%,n)
2.11
1.48
1.32
8.06
25.28
23.36
16.61
13.79
8.01
39Ar(k)
(%)
Table 9.10: Normal isochron table for MADERAS-002
Normal
Isochron
39(k)/36(a)
± 2σ
40(a+r)/36(a)
r.i.
± 2σ
BH5976
675 °C

164.9
± 14.5
305.3
± 26.9
0.9972
BH5977
720 °C

273.1
± 61.7
324.2
± 73.3
0.9992
BH5978
735 °C

375.8
± 151.7
334.5
± 135.0
0.9997
BH5979
800 °C

432.7
± 29.2
354.6
± 23.9
0.9981
BH5980
870 °C

543.8
± 22.5
378.9
± 15.7
0.9983
BH5981
940 °C

554.3
± 21.6
379.3
± 14.8
0.9985
BH5982
1025 °C

247.3
± 7.2
329.0
± 9.6
0.9891
BH5983
1125 °C

204.3
± 7.2
323.6
± 11.3
0.9943
BH5984
1225 °C

75.1
± 1.3
305.9
± 5.1
0.9810
Results
40(a)/36(a)
Normal
Isochron
± 5.4894
0.1524
± 1.87%
Minimal External Error
Analytical Error
Statistical F ratio
2.01
293.3429
Statistics
Error Magnification
1.0000
Number of Data
Points
9
± 2σ
Age
± 0.0199
± 13.03%
73.2
40(r)/39(k)
± 2σ
Convergence
Number of
Iterations
Calculated Line
MSWD
Table 9.10:Continued
± 2σ
(Ka)
± 9.5
0.32
± 13.03%
± 10.0
± 9.5
0.0000000004
12
Weighted York-2
Table 9.11: Inverse isochron table for MADERAS-002
Inverse
Isochron
39(k)/40(a+r)
± 2σ
36(a)/40(a+r)
r.i.
± 2σ
BH5976
675 °C

0.540065
± 0.003590
0.003276
± 0.000289
0.0403
BH5977
720 °C

0.842375
± 0.007590
0.003085
± 0.000697
0.0201
BH5978
735 °C

1.123452
± 0.011730
0.002990
± 0.001207
0.0174
BH5979
800 °C

1.220118
± 0.005072
0.002820
± 0.000190
0.0084
BH5980
870 °C

1.435059
± 0.003509
0.002639
± 0.000109
0.0239
BH5981
940 °C

1.461635
± 0.003123
0.002637
± 0.000103
0.0210
BH5982
1025 °C

0.751508
± 0.003242
0.003039
± 0.000089
0.1009
BH5983
1125 °C

0.631266
± 0.002357
0.003090
± 0.000108
0.0367
BH5984
1225 °C

0.245667
± 0.000813
0.003269
± 0.000055
0.0251
Results
40(a)/36(a)
± 2σ
40(r)/39
(k)
± 2σ
Age
Inverse
Isochron
293.3914
±
2.7383
± 0.93%
0.1525
± 0.0098
± 6.45%
73.2
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
2.01
1.0000
9
± 4.7
± 6.45%
0.31
± 5.5
± 4.7
Convergence
Number of Iterations
Calculated Line
69
± 2σ
(Ka)
MSW
D
Table 9.11: Continued
0.0000000087
4
Weighted York-2
70
940 °C
1025 °C
1125 °C
1225 °C
BH5981
BH5982
BH5983
BH5984
800 °C
870 °C
BH5979
BH5980
720 °C
735 °C
BH5977
BH5978
675 °C
BH5976
Relative
Abundances
0.784
0.630
0.0053435
Σ
1.654
1.351
1.747
1.842
3.057
18.609
10.599
4.213
0.0015133
0.0009584
0.0009644
0.0006261
0.0006967
0.0002755
0.0000514
0.0000776
0.0001800
%1σ









36Ar
1.047
2.583
2.559
2.556
2.551
2.553
2.689
3.280
3.199
2.860
%1σ
0.605
1.200
1.169
1.503
1.627
1.150
1.810
8.877
5.287
6.364
%1σ
1.3477499
0.1080367
0.1858010
0.2238121
0.3147667
0.3406039
0.1085748
0.0178237
0.0199021
0.0284290
39Ar
0.047
0.154
0.151
0.121
0.084
0.094
0.193
0.299
0.317
0.227
%1σ
Table 9.12: Continued
0.0177104
0.0019686
0.0026686
0.0029705
0.0039802
0.0039962
0.0012961
0.0002006
0.0002436
0.0003860
38Ar
1.6641773
0.4389562
0.2941307
0.2976138
0.2152504
0.2372194
0.0889355
0.0158561
0.0236116
0.0526036
40Ar
Sample = MAD002
Material = groundmass
Location = UW93C42
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
IGSN = Undefined
Preferred Age = Undefined
Classification = Undefined
Experiment Type = Undefined
0.044
0.059
0.110
0.178
0.066
0.078
0.077
0.428
0.320
0.243
%1σ
66.4
66.1
65.1
72.5
73.6
65.6
49.8
50.4
28.5
Age
± 31.8
± 24.4
± 16.8
± 10.0
± 10.8
± 22.1
± 152.4
± 117.5
± 75.9
± 2σ
(Ka)
Extraction Method = Undefined
Heating = 900 sec
Isolation = 15.00 min
Instrument = MAP215
Lithology = Undefined
Lat-Lon = Undefined - Undefined
Age Equations = Conventional
Negative Intensities = Forced Zero
Decay Constant 40K = 5.463 ± 0.107 E-10 1/a
Decay Constant 39Ar = 2.940 ± 0.029 E-07 1/h
Decay Constant 37Ar = 8.230 ± 0.082 E-04 1/h
No 36Cl Correction
No 36Cl Correction
Information on Analysis and Constants Used in Calculations
1.3569996
0.2968032
0.1876919
0.2270120
0.2216639
0.2676503
0.0936999
0.0151391
0.0182246
0.0291148
37Ar
Table 9.12: Relative abundances for MADERAS-002
3.40
8.69
10.19
22.09
22.01
16.67
11.66
8.85
3.20
40Ar(r)
(%)
8.01
13.79
16.61
23.36
25.28
8.06
1.32
1.48
2.11
39Ar(k)
(%)
0.156
0.425
0.424
0.610
0.547
0.498
0.506
0.469
0.420
K/Ca
± 2σ
± 0.008
± 0.022
± 0.022
± 0.031
± 0.028
± 0.027
± 0.033
± 0.030
± 0.024
71
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
Degassing
Patterns
4.40
0.68
0.004985
Σ
Σ
0.84
1.75
1.45
1.94
2.07
3.37
20.18
11.30
0.001435
0.000909
0.000905
0.000568
0.000626
0.000251
0.000047
0.000073
0.000172
%1σ









36Ar(a)
Inverse
Isochron
Normal
Isochron
Total
Fusion Age
0.1466
Age
Plateau
± 0.0126
± 8.62%
± 2σ
70.4
Age
± 0.0098
± 6.45%
± 0.0199
± 13.03%
73.2
73.2
± 5.5
± 4.7
± 4.7
± 6.45%
2.01
1.0000
0.31
2.01
1.0000
0.32
2.31
1.0000
0.34
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(c)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000358
0.000078
0.000050
0.000060
0.000059
0.000071
0.000025
0.000004
0.000005
0.000008
36Ar(ca)
1.05
2.58
2.56
2.56
2.55
2.55
2.69
3.28
3.20
2.86
%1σ
0.00
0.64
0.005344
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(cl)
0.293
K/Ca
0.427
1.357000
1.357000
0.296803
0.187692
0.227012
0.221664
0.267650
0.093700
0.015139
0.018225
0.029115
37Ar(ca)
1.05
1.05
2.58
2.56
2.56
2.55
2.55
2.69
3.28
3.20
2.86
%1σ
Statistical F ratio
Error Magnification
100.00
9
Statistical F ratio
Error Magnification
100.00
9
9
Statistical T Ratio
Error Magnification
100.00
9
39Ar(k)
(%,n)
Table 9.13: Degassing patterns for MADERAS-002
Minimal External Error
Analytical Error
0.1525
0.1524
± 10.0
± 9.5
± 7.2
± 10.51%
Minimal External Error
Analytical Error
68.1
± 7.6
± 7.2
± 9.5
± 13.03%
± 0.0149
± 10.51%
± 6.7
± 6.1
± 6.1
± 8.62%
± 2σ
(Ka)
Minimal External Error
Analytical Error
0.1418
Minimal External Error
Analytical Error
40(r)/39(k)
Results
Table 9.12: Continued
MSW
D
0.000932
0.000268
0.000170
0.000169
0.000106
0.000117
0.000047
0.000009
0.000014
0.000032
38Ar(a)
± 0.009
± 0.114
± 2σ
0.68
0.84
1.75
1.45
1.94
2.07
3.37
20.18
11.30
4.40
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(c)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
72
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
Additional
Parameters
0.05
0.016243









0.000000
0.15
0.15
0.002239
0.001301
0.000000
0.12
0.002697
0.000000
0.138352
0.137724
0.135605
0.151103
0.153389
0.136653
0.103769
0.105044
0.059268
1σ
0.03307
0.02537
0.01749
0.01038
0.01127
0.02302
0.15873
0.12235
0.438956
0.294131
0.297614
0.215250
0.237219
0.088936
0.015856
0.023612
0.052604
40(r+a)
0.51
1.346837
0.107837
0.185675
0.223659
0.314617
0.340424
0.108512
0.017814
0.019890
0.028409
39Ar(k)
0.05
0.15
0.15
0.12
0.08
0.09
0.19
0.30
0.32
0.23
%1σ
1.347750
0.000913
0.000200
0.000126
0.000153
0.000149
0.000180
0.000063
0.000010
0.000012
0.000020
39Ar(ca)
0.05
1.05
2.58
2.56
2.56
2.55
2.55
2.69
3.28
3.20
2.86
%1σ
0.191027
0.014919
0.025572
0.030329
0.047540
0.052217
0.014828
0.001848
0.002089
0.001684
40Ar(r)
5.26
23.90
18.42
12.90
6.87
7.34
16.84
152.97
116.47
133.38
%1σ
0.00026
0.00032
0.00053
0.00014
0.00018
0.00007
0.00007
0.00008
0.00013
1σ
4.063029
1.583042
1.329749
0.683841
0.696467
0.819117
0.889605
1.186388
1.850353
40Ar/39Ar
0.00671
0.00295
0.00287
0.00073
0.00085
0.00170
0.00464
0.00534
0.00615
1σ
2.747244
1.010177
1.014297
0.704217
0.785811
0.862999
0.849381
0.915713
1.024124
37Ar/39Ar
0.07109
0.02589
0.02596
0.01797
0.02008
0.02327
0.02797
0.02943
0.02938
1σ
0.014008
0.005158
0.004309
0.001989
0.002046
0.002538
0.002884
0.003901
0.006332
36Ar/39Ar
0.00011
0.00009
0.00006
0.00003
0.00004
0.00008
0.00054
0.00041
0.00027
1σ
1.473150
0.424037
0.268559
0.267285
0.167711
0.185002
0.074107
0.014008
0.021522
0.050920
40Ar(a)
Table 9.14: Additional parameters for MADERAS-002
10.72
0.018029
5.96
12.15
43.06
81.23
0.00
0.00
0.00
0.00
220.28
%1σ
0.000855
0.000400
0.000259
0.000104
0.000080
0.000000
0.000000
0.000000
0.000000
0.000011
38Ar(cl)
0.07905
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
40(r)/39(k)
0.000000
0.000000
0.000000
0.09
0.08
0.004106
0.000000
0.000000
0.000000
0.000000
38Ar(ca)
0.003794
0.30
0.19
0.32
0.000240
0.000215
0.23
0.000343
0.001309
%1σ
38Ar(k)
Table 9.13: Continued
128.307
128.272
128.237
128.202
128.167
128.132
128.094
128.055
128.020
Time
(days)
0.68
0.84
1.75
1.45
1.94
2.07
3.37
20.18
11.30
4.40
%1σ
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
12.61302788
12.60438041
12.59556610
12.58693060
12.57812849
12.56950495
12.56019817
12.55038181
12.54177729
37Ar
(decay)
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(c)
1.00090589
1.00090565
1.00090540
1.00090515
1.00090490
1.00090465
1.00090439
1.00090411
1.00090387
39Ar
(decay)
1.664177
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(k)
2.591E-15
1.736E-15
1.757E-15
1.270E-15
1.400E-15
5.249E-16
9.358E-17
1.394E-16
3.105E-16
40Ar
(moles)
0.85
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
73
Intercept
Values
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
0.000240
0.000138
0.000112
0.000343
0.000777
0.000708
0.001057
0.001056
0.001627
36Ar
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
Procedure
Blanks
0.000002
0.000004
0.000006
0.000004
0.000011
0.000008
0.000011
0.000014
0.000009
1σ
0.000056
0.000058
0.000059
0.000062
0.000066
0.000069
0.000073
0.000078
0.000083
36Ar
0.9080
0.1250
0.0801
0.8405
0.8335
0.8974
0.8942
0.8712
0.9759
r2
0.000009
0.000013
0.000014
0.000020
0.000025
0.000031
0.000038
0.000046
0.000054
37Ar
0.000016
0.000016
0.000016
0.000016
0.000016
0.000016
0.000016
0.000016
0.000016
1σ
0.000027
0.000025
0.000024
0.000021
0.000018
0.000016
0.000012
0.000008
0.000004
38Ar
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
1σ
LIN
EXP
LIN
EXP
LIN
EXP
LIN
LIN
LIN
7 of 8
8 of 8
7 of 8
8 of 8
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
0.002366
0.001487
0.001238
0.007588
0.021629
0.017911
0.018336
0.015164
0.023945
37Ar
0.000027
0.000024
0.000020
0.000067
0.000067
0.000049
0.000058
0.000049
0.000116
1σ
0.9335
0.7950
0.5745
0.9594
0.9946
0.9943
0.9932
0.9931
0.9847
r2
LIN
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
39Ar
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.000016
0.000004
0.000003
0.000016
0.000034
0.000042
0.000030
0.000009
0.000054
Table 9.16: Intercept values for MADERAS-002
0.000007
0.000007
0.000007
0.000007
0.000007
0.000007
0.000007
0.000007
0.000007
1σ
Table 9.15: Procedure blanks for MADERAS-002
0.000417
0.000271
0.000227
0.001331
0.004055
0.004036
0.003013
0.002704
0.001992
38Ar
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
1σ
0.000022
0.000006
0.000014
0.000021
0.000045
0.000064
0.000044
0.000029
0.000021
1σ
0.016221
0.017215
0.017435
0.017974
0.018194
0.018473
0.019280
0.021047
0.023296
40Ar
0.4128
0.8349
0.2383
0.8601
0.9149
0.8528
0.8256
0.9051
0.8577
r2
LIN
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
0.000050
0.000050
0.000050
0.000050
0.000050
0.000050
0.000050
0.000050
0.000050
1σ
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
74
0.000063
0.000062
0.000052
0.000208
0.000306
0.000247
0.000264
0.000276
0.000164
0.028564
0.019989
0.017902
0.109044
0.342061
0.316123
0.224776
0.186586
0.108542
Sample
MAD002
MAD002
MAD002
MAD002
MAD002
MAD002
MAD002
MAD002
MAD002
Sample
Parameters
BH5976
BH5977
BH5978
BH5979
BH5980
BH5981
BH5982
BH5983
BH5984
675 °C
720 °C
735 °C
800 °C
870 °C
940 °C
1025 °C
1125 °C
1225 °C
0.9952
0.9874
0.9958
0.9972
0.9993
0.9995
0.9988
0.9981
0.9977
r2
LIN
EXP
LIN
EXP
EXP
EXP
EXP
EXP
EXP
8 of 8
8 of 8
4 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.068824
0.040826
0.033291
0.106910
0.255413
0.233724
0.316894
0.315178
0.462252
40Ar
r2
0.9923
0.9797
0.9561
0.9996
0.9992
0.9992
0.9956
0.9984
0.9997
1σ
0.000118
0.000057
0.000046
0.000046
0.000177
0.000133
0.000528
0.000319
0.000254
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
Material
UW93C42
UW93C42
UW93C42
UW93C42
UW93C42
UW93C42
UW93C42
UW93C42
UW93C42
Location
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Analyst
675
720
735
800
870
940
1025
1125
1225
Standard
(in Ma)
28.201
28.201
28.201
28.201
28.201
28.201
28.201
28.201
28.201
Table 9.17: Sample parameters for MADERAS-002
1σ
39Ar
Table 9.16: Continued
Temp
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
%1σ
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
J
8 of 8
8 of 8
7 of 8
5 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
%1σ
Hour
20
OCT
2011
17
5.902E-15
20
OCT
2011
18
30
1
5.902E-15
20
OCT
2011
19
0.03
1
5.902E-15
20
OCT
2011
1.005096
0.03
1
5.902E-15
20
OCT
1.005096
0.03
1
5.902E-15
20
1.005096
0.03
1
5.902E-15
1.005096
0.03
1
1.005096
0.03
1
1.005096
0.03
1.005096
0.03
1.005096
0.03
1.005096
Volume
Ratio
Irradiation
Project
Experiment
Nmb
Year
5.902E-15
%1σ
Resist
Month
1
1
MDF
Min
Sensitivity
(mol/volt)
Day
Table 9.17: Continued
Standard
Name
40
001
UW93
UW93C
UW93C42
01
FCS
001
UW93
UW93C
UW93C42
01
FCS
27
001
UW93
UW93C
UW93C42
01
FCS
20
21
001
UW93
UW93C
UW93C42
01
FCS
2011
21
11
001
UW93
UW93C
UW93C42
01
FCS
OCT
2011
22
02
001
UW93
UW93C
UW93C42
01
FCS
20
OCT
2011
22
52
001
UW93
UW93C
UW93C42
01
FCS
5.902E-15
20
OCT
2011
23
43
001
UW93
UW93C
UW93C42
01
FCS
5.902E-15
21
OCT
2011
00
33
001
UW93
UW93C
UW93C42
01
FCS
Table 9.18: Irradiation constants for MADERAS-002
Irradiation
Constants
40/36(a)
%1
σ
40/36
(c)
%1σ
38/36
(a)
%
1σ
38/36
(c)
%
1σ
39/37(ca)
%
1σ
38/37
(ca)
%
1σ
36/37(ca)
%1σ
BH5976
675 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5977
720 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5978
735 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5979
800 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5980
870 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5981
940 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5982
1025 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5983
1125 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
BH5984
1225 °C
295.5
0
0.018
35
0.1869
0
1.493
3
0.000673
0
0
0
0.000264
0
Table 9.18: Continued
40/39(k)
%1σ
38/39(k)
%1σ
36/38(cl)
%1σ
K/Ca
%1σ
K/Cl
%1σ
Ca/Cl
%1σ
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
75
UW93C42.AGE >>> MAD002 >>> UW93C PROJECT
Ar-Ages in Ka
WEIGHTED PLATEAU
70.4 ± 6.1
TOTAL FUSION
68.1 ± 7.2
NORMAL ISOCHRON
73.2 ± 9.5
INVERSE ISOCHRON
73.2 ± 4.7
200
150
100
MSWD
0.34
50
70.4 ± 6.1 Ka
0
50
Sample Info
100
groundmass
UW93C42
Brian Jicha
150
IRR = UW93
J = 0.00026230 ± 0.00000013
200
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
Figure 9.1: Age plateau for MADERAS-002
UW93C42.AGE >>> MAD002 >>> UW93C PROJECT
0.9
Ar-Ages in Ka
WEIGHTED PLATEAU
70.4 ± 6.1
TOTAL FUSION
68.1 ± 7.2
NORMAL ISOCHRON
73.2 ± 9.5
INVERSE ISOCHRON
73.2 ± 4.7
0.8
0.7
0.6
0.293 ± 0.114
0.5
0.4
Sample Info
0.3
groundmass
UW93C42
Brian Jicha
0.2
IRR = UW93
J = 0.00026230 ± 0.00000013
0.1
0
10
20
30
40
50
60
Cumulative 39Ar Released [ % ]
Figure 9.2: K-Ca plateau for MADERAS-002
76
70
80
90
100
UW93C42.AGE >>> MAD002 >>> UW93C PROJECT
500
Ar-Ages in Ka
WEIGHTED PLATEAU
70.4 ± 6.1
TOTAL FUSION
68.1 ± 7.2
NORMAL ISOCHRON
73.2 ± 9.5
INVERSE ISOCHRON
73.2 ± 4.7
450
400
350
300
MSWD
0.32
250
40AR/36AR INTERCEPT
293.3 ± 5.5
200
150
Sample Info
100
groundmass
UW93C42
Brian Jicha
IRR = UW93
J = 0.00026230 ± 0.00000013
50
0
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
39Ar / 36Ar
Figure 9.3: Normal isochron for MADERAS-002
UW93C42.AGE >>> MAD002 >>> UW93C PROJECT
0.0045
Ar-Ages in Ka
WEIGHTED PLATEAU
70.4 ± 6.1
TOTAL FUSION
68.1 ± 7.2
NORMAL ISOCHRON
73.2 ± 9.5
INVERSE ISOCHRON
73.2 ± 4.7
0.0040
0.0035
0.0030
MSWD
0.31
0.0025
40AR/36AR INTERCEPT
293.4 ± 2.7
0.0020
0.0015
Sample Info
0.0010
groundmass
UW93C42
Brian Jicha
0.0005
IRR = UW93
J = 0.00026230 ± 0.00000013
0.0000
0
1
2
3
4
5
6
39Ar / 40Ar
Figure 9.4: Inverse isochron for MADERAS-002
77
7
8
9
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
0.549483
0.003154
Σ
Total Fusion
Age
2.154093
0.048528
0.223142
0.581165
0.554642
0.382787
0.151495
0.119877
0.041692
0.050765
39Ar(k)
± 0.0044
± 1.34%
± 2σ
Age
± 0.0073
± 2.22%
157.7
Minimal External Error
Analytical Error
0.3284
Minimal External Error
Analytical Error
0.3280
40(r)/39(k)
± 7.1
± 3.5
± 3.5
± 2.23%
± 6.5
± 2.1
± 2.2
± 1.37%
± 2σ
(Ka)
Age ± 2σ
(Ka)
172.7 ± 62.3
156.2 ± 8.4
158.5 ± 3.1
156.4 ± 3.6
157.4 ± 6.3
157.5 ± 15.8
157.9 ± 22.6
140.3 ± 56.5
171.1 ± 69.0
157.5
0.707430
0.017458
0.072619
0.191857
0.180650
0.125462
0.049685
0.039421
0.012185
0.018094
40Ar(r)
Table 9.19: Continued
0.000836
0.000000
0.000000
0.000000
0.000000
0.000000
0.000145
0.000223
0.000234
0.000233
38Ar(cl)
Age Plateau
Results
0.013712
0.052741
0.103817
0.093738
0.083057
0.051685
0.059100
0.037967
0.053665
0.000600
0.000519
0.000467
0.000320
0.000246
0.000205
0.000255
0.000219
0.000323
37Ar(ca)









36Ar(a)
Sample = MAD003
Material = groundmass
Location = UW93C43
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000037
FCS = 28.201 ± 0.023 Ma
Information
on Analysis
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
Incremental
Heating
40Ar(r)
(%)
8.97
32.12
58.16
65.61
63.33
45.05
34.37
15.82
15.94
Table 9.19: Incremental heating summary for MADERAS-003
2.31
1.0000
0.21
MSWD
9.2.2 Sample MADERAS-003
78
0.67
K/Ca
1.52
1.82
2.41
2.54
1.98
1.26
0.87
0.47
0.41
K/Ca
9
1.69
± 0.09
± 0.10
± 0.12
± 0.13
± 0.10
± 0.07
± 0.05
± 0.03
± 0.02
± 2σ
± 0.34
± 2σ
± 0.03
Statistical T Ratio
Error Magnification
100.00
9
39Ar(k)
(%,n)
39Ar(k)
(%)
2.25
10.36
26.98
25.75
17.77
7.03
5.57
1.94
2.36
Table 9.20: Normal isochron table for MADERAS-003
Normal
Isochron
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
39(k)/36(a)
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
80.9
429.6
1244.2
1730.8
1557.2
738.8
470.6
190.1
157.2









40(a+r)/36(a)
± 2σ
± 2.9
± 10.9
± 32.6
± 72.8
± 106.5
± 60.1
± 34.9
± 14.3
± 12.0
324.6
435.3
706.2
859.2
805.9
537.8
450.3
351.1
351.5
r.i.
± 2σ
± 11.5
± 11.1
± 18.7
± 36.3
± 55.2
± 43.8
± 33.5
± 26.5
± 26.8
0.9888
0.9959
0.9901
0.9945
0.9970
0.9963
0.9940
0.9919
0.9941
Results
40(a)/36(a)
Normal
Isochron
296.2474
40(r)/39(k)
± 2σ
± 7.0069
± 2.37%
0.3273
Age
± 2σ
± 0.0074
± 2.26%
157.1
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
2.01
1.0000
9
Convergence
Number of Iterations
Calculated Line
± 2σ
(Ka)
± 3.6
± 2.28%
MSWD
Table 9.20: Continued
0.23
± 7.1
± 3.6
0.0000000032
33
Weighted York-2
Table 9.21: Inverse isochron table for MADERAS-003
Inverse
Isochron
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
39(k)/40(a+r)
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C









0.249345
0.986861
1.761703
2.014361
1.932287
1.373782
1.045234
0.541437
0.447222
36(a)/40(a+r)
± 2σ
± 0.001322
± 0.002273
± 0.006518
± 0.008884
± 0.010225
± 0.009596
± 0.008486
± 0.005205
± 0.003694
0.003081
0.002297
0.001416
0.001164
0.001241
0.001859
0.002221
0.002849
0.002845
r.i.
± 2σ
± 0.000109
± 0.000058
± 0.000037
± 0.000049
± 0.000085
± 0.000152
± 0.000165
± 0.000215
± 0.000217
0.0836
0.0690
0.1296
0.0821
0.0510
0.0709
0.0709
0.0757
0.0478
Results
Inverse
Isochron
40(a)/36(a)
296.3144
± 2σ
± 3.5081
± 1.18%
40(r)/39(k)
0.3273
Age
± 2σ
± 0.0037
± 1.13%
157.1
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
2.01
1.0000
9
Convergence
Number of Iterations
Calculated Line
79
± 2σ
(Ka)
± 1.8
± 1.17%
MSWD
Table 9.21 Continued
0.23
± 6.4
± 1.8
0.0000002122
4
Weighted York-2
80
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
Relative
Abundances
0.0006032
3.645
0.793
0.0032994
Σ
3.593
3.488
3.806
3.131
1.942
1.228
1.233
1.752
0.0003371
0.0002294
0.0002703
0.0002187
0.0002677
0.0003452
0.0004945
0.0005334
%1σ









36Ar
0.945
2.781
2.643
2.615
2.628
2.554
2.552
2.561
2.695
2.949
%1σ
0.424
2.412
2.929
0.997
1.065
0.819
0.810
1.048
1.531
2.479
%1σ
2.1544632
0.0508013
0.0417172
0.1199172
0.1515298
0.3828430
0.5547046
0.5812352
0.2231777
0.0485373
39Ar
0.045
0.308
0.306
0.240
0.145
0.154
0.102
0.051
0.056
0.176
%1σ
Table 9.22: Continued
0.0260553
0.0009057
0.0007777
0.0017164
0.0020108
0.0045456
0.0064551
0.0064066
0.0025639
0.0006735
38Ar
1.6395476
0.1135123
0.0770018
0.1146896
0.1102759
0.1981005
0.2753436
0.3298885
0.2261132
0.1946222
40Ar
Sample = MAD003
Material = groundmass
Location = UW93C43
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000037
FCS = 28.201 ± 0.023 Ma
IGSN = Undefined
Preferred Age = Undefined
Classification = Undefined
Experiment Type = Undefined
0.074
0.274
0.371
0.327
0.318
0.215
0.195
0.178
0.100
0.198
%1σ
171.1
140.3
157.9
157.5
157.4
156.4
158.5
156.2
172.7
Age
Extraction Method = Undefined
Heating = 900 sec
Isolation = 15.00 min
Instrument = MAP215
Lithology = Undefined
Lat-Lon = Undefined - Undefined
Age Equations = Conventional
Negative Intensities = Forced Zero
Decay Constant 40K = 5.463 ± 0.107 E-10 1/a
Decay Constant 39Ar = 2.940 ± 0.029 E-07 1/h
Decay Constant 37Ar = 8.230 ± 0.082 E-04 1/h
No 36Cl Correction
No 36Cl Correction
Information on Analysis and Constants Used in Calculations
0.5494829
0.0536645
0.0379672
0.0591004
0.0516848
0.0830572
0.0937375
0.1038174
0.0527415
0.0137125
37Ar
Table 9.22: Relative abundances for MADERAS-003
± 69.0
± 56.5
± 22.6
± 15.8
± 6.3
± 3.6
± 3.1
± 8.4
± 62.3
± 2σ
(Ka)
15.94
15.82
34.37
45.05
63.33
65.61
58.16
32.12
8.97
40Ar(r)
(%)
2.36
1.94
5.57
7.03
17.77
25.75
26.98
10.36
2.25
39Ar(k)
(%)
0.41
0.47
0.87
1.26
1.98
2.54
2.41
1.82
1.52
K/Ca
± 0.02
± 0.03
± 0.05
± 0.07
± 0.10
± 0.13
± 0.12
± 0.10
± 0.09
± 2σ
81
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
BH5955
BH5956
BH5957
BH5958
BH5959
845 °C
900 °C
BH5953
BH5954

0.000467
1.31
0.83
0.003154
Σ
Σ
3.81
3.76
3.70
4.06
3.42
2.10
0.000323
0.000219
0.000255
0.000205
0.000246
0.000320
1.27
1.76
%1σ






0.000519
0.000600
785 °C
BH5952

720 °C
BH5951

36Ar(a)
Degassing
Patterns
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(c)
Inverse
Isochron
Normal
Isochron
Total Fusion
Age
Age Plateau
Results
± 1.8
1.0000
2.01
0.23
1.0000
2.01
0.23
1.0000
2.31
0.21
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000145
0.000014
0.000010
0.000016
0.000014
0.000022
0.000025
0.000027
0.000014
0.000004
36Ar(ca)
0.94
2.78
2.64
2.61
2.63
2.55
2.55
2.56
2.70
2.95
%1σ
0.00
0.79
0.003299
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(cl)
0.549483
0.549483
0.053665
0.037967
0.059100
0.051685
0.083057
0.093738
0.103817
0.052741
0.013712
37Ar(ca)
0.67
K/Ca
1.69
0.94
0.94
2.78
2.64
2.61
2.63
2.55
2.55
2.56
2.70
2.95
%1σ
0.000590
0.000060
0.000041
0.000048
0.000038
0.000046
0.000060
0.000087
0.000097
0.83
3.81
3.76
3.70
4.06
3.42
2.10
1.31
1.27
1.76
%1σ
± 0.03
± 0.34
± 2σ
0.000112
38Ar(a)
Error Magnification
Statistical F ratio
100.00
9
Error Magnification
Statistical F ratio
100.00
9
9
Error Magnification
Statistical T Ratio
100.00
9
39Ar(k)
(%,n)
Table 9.23: Degassing patterns for MADERAS-003
± 6.4
± 1.8
± 1.17%
Analytical Error
157.1
Minimal External Error
± 0.0037
± 1.13%
± 3.6
0.3273
± 7.1
± 3.6
± 2.28%
Analytical Error
157.1
Minimal External Error
0.3273
± 0.0074
± 2.26%
± 3.5
± 3.5
± 2.23%
± 7.1
157.7
Analytical Error
± 0.0073
± 2.22%
Minimal External Error
0.3284
± 2.1
± 2.2
± 1.37%
± 2σ
(Ka)
± 6.5
157.5
Age
Analytical Error
± 0.0044
± 1.34%
± 2σ
Minimal External Error
0.3280
40(r)/39(k)
Table 9.22: Continued
MSW
D
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(c)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.025978
0.000612
0.000503
0.001446
0.001827
0.004616
0.006689
0.007009
0.002691
0.000585
38Ar(k)
0.05
0.31
0.31
0.24
0.15
0.15
0.10
0.05
0.06
0.18
%1σ
82
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
720 °C









0.356417
0.292261
0.328845
0.327961
0.327760
0.325706
0.330124
0.325439
0.359757
0.07183
0.05884
0.02349
0.01642
0.00660
0.00373
0.00327
0.00878
0.06483
0.05
0.31
0.31
0.24
0.15
0.15
0.10
0.05
0.06
0.18
%1σ
2.154463
0.000370
0.000036
0.000026
0.000040
0.000035
0.000056
0.000063
0.000070
0.000035
0.000009
39Ar(ca)
0.05
0.94
2.78
2.64
2.61
2.63
2.55
2.55
2.56
2.70
2.95
%1σ
0.707430
0.018094
0.012185
0.039421
0.049685
0.125462
0.180650
0.191857
0.072619
0.017458
40Ar(r)
1.11
20.15
20.13
7.14
5.00
2.01
1.14
0.99
2.70
18.02
%1σ
0.932117
0.095419
0.064817
0.075268
0.060591
0.072638
0.094694
0.138032
0.153494
0.177164
40Ar(a)
0.113512
0.077002
0.114690
0.110276
0.198101
0.275344
0.329888
0.226113
0.194622
0.00031
0.00029
0.00038
0.00035
0.00043
0.00054
0.00059
0.00023
0.00039
1σ
2.234438
1.845807
0.956407
0.727750
0.517446
0.496379
0.567564
1.013153
4.009748
40Ar/39Ar
0.00923
0.00887
0.00388
0.00254
0.00137
0.00109
0.00105
0.00117
0.01063
1σ
1.056362
0.910109
0.492844
0.341087
0.216948
0.168986
0.178615
0.236321
0.282514
37Ar/39Ar
0.02955
0.02422
0.01294
0.00898
0.00555
0.00432
0.00458
0.00637
0.00834
1σ
0.006635
0.005498
0.002254
0.001443
0.000699
0.000622
0.000851
0.002390
0.012427
36Ar/39Ar
0.00024
0.00020
0.00008
0.00005
0.00002
0.00001
0.00001
0.00003
0.00022
1σ
0.83
3.81
3.76
3.70
4.06
3.42
2.10
1.31
1.27
1.76
%1σ
Table 9.24: Additional parameters for MADERAS-003
2.154093
0.050765
0.041692
0.119877
0.151495
0.382787
0.554642
0.581165
0.223142
0.048528
39Ar(k)
40(r+a)
0.16
0.027403
1σ
5.06
9.46
9.78
7.87
14.87
0.00
0.00
0.00
0.00
0.00
%1σ
0.000836
0.000233
0.000234
0.000223
0.000145
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(cl)
40(r)/39(k)
0.00
0.00
0.000000
0.000000
BH5952
BH5951
Additional
Parameters
0.00
0.00
0.000000
0.000000
0.00
0.00
0.000000
0.000000
0.00
0.00
0.00
0.000000
0.000000
0.00
0.000000
0.000000
%1σ
38Ar(ca)
Table 9.23: Continued
127.422
127.388
127.352
127.317
127.283
127.247
127.213
127.178
127.142
Time
(days)
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(c)
12.39452949
12.38603182
12.37737020
12.36888430
12.36040422
12.35176052
12.34329217
12.33482964
0.67
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
1.00089964
1.00089940
1.00089915
1.00089890
1.00089866
1.00089841
1.00089816
1.00089792
1.00089767
39Ar
(decay)
1.639548
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(k)
12.32620382
37Ar
(decay)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
6.699E-16
4.545E-16
6.769E-16
6.508E-16
1.169E-15
1.625E-15
1.947E-15
1.335E-15
1.149E-15
40Ar
(moles)
83
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
Intercept
Values
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
0.000679
0.000611
0.000576
0.000427
0.000353
0.000310
0.000371
0.000338
0.000458
36Ar
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
Procedure
Blanks
0.000009
0.000004
0.000003
0.000004
0.000007
0.000007
0.000008
0.000007
0.000011
1σ
0.000063
0.000066
0.000070
0.000074
0.000080
0.000087
0.000095
0.000104
0.000114
36Ar
0.6817
0.5854
0.8210
0.5925
0.8906
0.9519
0.9441
0.4070
r2
0.000011
0.000011
0.000012
0.000015
0.000023
0.000038
0.000067
0.000107
0.000163
37Ar
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
1σ
0.000005
0.000005
0.000005
0.000006
0.000007
0.000009
0.000012
0.000015
0.000019
38Ar
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
1σ
EXP
PAR
LIN
EXP
AVE
EXP
LIN
EXP
EXP
7 of 8
7 of 8
6 of 8
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.001142
0.004357
0.008561
0.007728
0.006852
0.004285
0.004920
0.003223
0.004564
37Ar
0.000013
0.000041
0.000040
0.000032
0.000028
0.000030
0.000032
0.000022
0.000051
1σ
0.9399
0.9392
0.9845
0.9903
0.9888
0.9692
0.9760
0.9778
0.9268
r2
LIN
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
39Ar
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.000000
0.000004
0.000008
0.000011
0.000015
0.000019
0.000023
0.000027
0.000030
Table 9.26: Intercept values for MADERAS-003
0.000005
0.000005
0.000005
0.000005
0.000005
0.000005
0.000005
0.000005
0.000006
1σ
Table 9.25: Procedure blanks for MADERAS-003
0.000686
0.002597
0.006482
0.006532
0.004603
0.002042
0.001747
0.000801
0.000935
38Ar
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
1σ
0.000012
0.000038
0.000067
0.000051
0.000036
0.000018
0.000012
0.000020
0.000019
1σ
0.019186
0.018408
0.018943
0.020180
0.022012
0.024165
0.026176
0.027276
0.027176
40Ar
0.7761
0.8565
0.9138
0.9660
0.9412
0.9719
0.9800
0.7901
0.8804
r2
EXP
EXP
EXP
EXP
EXP
LIN
EXP
EXP
LIN
0.000192
0.000184
0.000189
0.000202
0.000220
0.000242
0.000262
0.000273
0.000272
1σ
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
7 of 8
8 of 8
7 of 8
Table 9.26: Continued
39Ar
1σ
r2
0.048759
0.224200
0.583894
0.557246
0.384604
0.152239
0.120487
0.041934
0.051063
0.000085
0.000117
0.000271
0.000558
0.000588
0.000219
0.000288
0.000128
0.000157
0.9970
0.9998
0.9999
0.9993
0.9982
0.9990
0.9967
0.9927
0.9924
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
8 of 8
8 of 8
8 of 8
8 of 8
6 of 8
7 of 8
8 of 8
8 of 8
8 of 8
40Ar
1σ
r2
0.213808
0.244521
0.348832
0.295523
0.220112
0.134441
0.140865
0.104278
0.140689
0.000335
0.000133
0.000556
0.000499
0.000364
0.000254
0.000269
0.000084
0.000152
0.9977
0.9997
0.9955
0.9943
0.9937
0.9954
0.9961
0.9996
0.9991
PAR
LIN
EXP
EXP
EXP
EXP
EXP
PAR
LIN
8 of 8
6 of 8
8 of 8
6 of 8
8 of 8
7 of 8
8 of 8
6 of 8
6 of 8
Sample
Parameters
Sample
Material
Location
Analyst
Temp
Table 9.27: Sample parameters for MADERAS-003
Standard
(in Ma)
%1σ
J
%1σ
BH5951
720 °C
MAD003
groundmass
UW93C43
Brian Jicha
720
28.201
0.08
0.0002623
0.14
BH5952
785 °C
MAD003
groundmass
UW93C43
Brian Jicha
785
28.201
0.08
0.0002623
0.14
BH5953
845 °C
MAD003
groundmass
UW93C43
Brian Jicha
845
28.201
0.08
0.0002623
0.14
BH5954
900 °C
MAD003
groundmass
UW93C43
Brian Jicha
900
28.201
0.08
0.0002623
0.14
BH5955
960 °C
MAD003
groundmass
UW93C43
Brian Jicha
960
28.201
0.08
0.0002623
0.14
BH5956
1025 °C
MAD003
groundmass
UW93C43
Brian Jicha
1025
28.201
0.08
0.0002623
0.14
BH5957
1095 °C
MAD003
groundmass
UW93C43
Brian Jicha
1095
28.201
0.08
0.0002623
0.14
BH5958
1160 °C
MAD003
groundmass
UW93C43
Brian Jicha
1160
28.201
0.08
0.0002623
0.14
BH5959
1225 °C
MAD003
groundmass
UW93C43
Brian Jicha
1225
28.201
0.08
0.0002623
0.14
UW93C43
01
FCS
UW93C
UW93C43
01
FCS
UW93
UW93C
UW93C43
01
FCS
001
UW93
UW93C
UW93C43
01
FCS
58
001
UW93
UW93C
UW93C43
01
FCS
00
48
001
UW93
UW93C
UW93C43
01
FCS
2011
01
38
001
UW93
UW93C
UW93C43
01
FCS
OCT
2011
02
29
001
UW93
UW93C
UW93C43
01
FCS
OCT
2011
03
19
001
UW93
UW93C
UW93C43
01
FCS
5.902E-15
19
OCT
2011
20
1
5.902E-15
19
OCT
2011
21
27
0.02
1
5.902E-15
19
OCT
2011
22
1.005474
0.02
1
5.902E-15
19
OCT
2011
1.005474
0.02
1
5.902E-15
19
OCT
1.005474
0.02
1
5.902E-15
20
1.005474
0.02
1
5.902E-15
1.005474
0.02
1
1.005474
0.02
1
Vol.
Ratio
1.005474
0.02
1.005474
0.02
1.005474
Irradiati
on
Project
36
001
UW93
001
UW93
17
001
23
07
2011
23
OCT
2011
20
OCT
5.902E-15
20
5.902E-15
20
Hour
%1σ
Resist
1
MDF
Min
Year
UW93C
Month
Stand
ard
Name
Sensitivity
(mol/volt)
Day
Experiment
Nmb
Table 9.27: Continued
84
85
BH5951
BH5952
BH5953
BH5954
BH5955
BH5956
BH5957
BH5958
BH5959
720 °C
785 °C
845 °C
900 °C
960 °C
1025 °C
1095 °C
1160 °C
1225 °C
Irradiation
Constants
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
40/36(a)
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
%1σ
38/39(k)
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
35
35
35
35
35
35
35
35
35
%1σ
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
40/36(c)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
38/36(c)
3
3
3
3
3
3
3
3
3
%1σ
0
0
0
0
0
0
0
0
0
%1σ
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
K/Ca
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
39/37(ca)
K/Cl
Table 9.28: Continued
36/38(cl)
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
38/36(a)
0
0
0
0
0
0
0
0
0
Ca/Cl
0
0
0
0
0
0
0
0
0
%1σ
Table 9.28: Irradiation constants for MADERAS-003
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
38/37
(ca)
0
0
0
0
0
0
0
0
0
%1σ
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
36/37(ca)
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
40/39
(k)
0
0
0
0
0
0
0
0
0
%1σ
UW93C43.AGE >>> MAD003 >>> UW93C PROJECT
340
Ar-Ages in Ka
320
WEIGHTED PLATEAU
157.5 ± 2.2
TOTAL FUSION
157.7 ± 3.5
NORMAL ISOCHRON
157.1 ± 3.6
INVERSE ISOCHRON
157.1 ± 1.8
300
280
260
240
MSWD
0.21
220
200
157.5 ± 2.2 Ka
180
160
Sample Info
140
groundmass
UW93C43
Brian Jicha
120
100
IRR = UW93
J = 0.00026230 ± 0.00000037
80
60
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
Figure 9.5: Age plateau for MADERAS-003
UW93C43.AGE >>> MAD003 >>> UW93C PROJECT
3.9
Ar-Ages in Ka
3.6
WEIGHTED PLATEAU
157.5 ± 2.2
TOTAL FUSION
157.7 ± 3.5
NORMAL ISOCHRON
157.1 ± 3.6
INVERSE ISOCHRON
157.1 ± 1.8
3.3
3.0
2.7
2.4
2.1
1.8
0.67 ± 0.34
1.5
1.2
Sample Info
0.9
groundmass
UW93C43
Brian Jicha
0.6
IRR = UW93
J = 0.00026230 ± 0.00000037
0.3
0.0
0
10
20
30
40
50
60
Cumulative 39Ar Released [ % ]
Figure 9.6: K-Ca plateau for MADERAS-003
86
70
80
90
100
UW93C43.AGE >>> MAD003 >>> UW93C PROJECT
1100
Ar-Ages in Ka
WEIGHTED PLATEAU
157.5 ± 2.2
TOTAL FUSION
157.7 ± 3.5
NORMAL ISOCHRON
157.1 ± 3.6
INVERSE ISOCHRON
157.1 ± 1.8
1000
900
800
700
MSWD
0.23
600
40AR/36AR INTERCEPT
296.2 ± 7.0
500
400
Sample Info
300
groundmass
UW93C43
Brian Jicha
200
IRR = UW93
J = 0.00026230 ± 0.00000037
100
0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
39Ar / 36Ar
Figure 9.7: Normal isochron for MADERAS-003
UW93C43.AGE >>> MAD003 >>> UW93C PROJECT
0.0045
Ar-Ages in Ka
WEIGHTED PLATEAU
157.5 ± 2.2
TOTAL FUSION
157.7 ± 3.5
NORMAL ISOCHRON
157.1 ± 3.6
INVERSE ISOCHRON
157.1 ± 1.8
0.0040
0.0035
0.0030
MSWD
0.23
0.0025
40AR/36AR INTERCEPT
296.3 ± 3.5
0.0020
0.0015
Sample Info
0.0010
groundmass
UW93C43
Brian Jicha
0.0005
IRR = UW93
J = 0.00026230 ± 0.00000037
0.0000
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
39Ar / 40Ar
Figure 9.8: Inverse isochron for MADERAS-003
87
2.7
3.0
3.3
3.6
3.9
1.610527
0.026603
Σ
Sample = MAD004
Material = groundmass
Location = UW93C44
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
Information
on Analysis
Total Fusion
Age
0.480022
0.023839
0.012243
0.047412
0.032112
0.062204
0.094103
0.090463
0.056423
0.040385
0.020838
39Ar(k)
± 0.0462
± 17.25%
± 2σ
128.7
± 0.0643
± 24.53%
125.8
Minimal External Error
Analytical Error
0.2619
Minimal External Error
Analytical Error
0.2680
40(r)/39(k)
Age
0.125738
0.002937
0.007736
0.016062
0.009296
0.018294
0.025853
0.024165
0.013410
0.007986
0.000000
40Ar(r)
Table 9.29: Continued
0.000802
0.000082
0.000074
0.000051
0.000000
0.000000
0.000000
0.000065
0.000094
0.000208
0.000229
38Ar(cl)
Age Plateau
Results
0.046903
0.031165
0.138734
0.078312
0.137666
0.203548
0.238072
0.225612
0.198125
0.312391
0.003777
0.001688
0.003081
0.001587
0.001779
0.001863
0.001834
0.002292
0.004698
0.004005









675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
37Ar(ca)
36Ar(a)
Incremental
Heating
± 31.2
± 30.9
± 30.9
± 24.53%
± 22.8
± 22.2
± 22.2
± 17.25%
± 225.5
± 436.5
± 147.7
± 160.0
± 66.9
± 46.6
± 31.5
± 92.0
± 95.6
± 0.0
± 2σ
(Ka)
± 2σ
(Ka)
59.1
303.4
162.7
139.0
141.2
131.9
128.3
114.1
94.9
0.0
Age
Table 9.29: Incremental heating summary for MADERAS-004
2.31
1.0000
0.136
10
0.128
Statistical T Ratio
Error Magnification
95.66
9
K/Ca
± 0.012
± 0.009
± 0.008
± 0.009
± 0.010
± 0.010
± 0.008
± 0.006
± 0.005
± 0.001
± 2σ
± 0.002
± 0.031
± 2σ
0.219
0.169
0.147
0.176
0.194
0.199
0.163
0.108
0.088
0.029
K/Ca
4.97
2.55
9.88
6.69
12.96
19.60
18.85
11.75
8.41
4.34
39Ar(k)
(%)
39Ar(k)
(%,n)
0.26
1.53
1.73
1.94
3.36
4.49
4.27
1.94
0.57
0.00
40Ar(r)
(%)
0.25
MSWD
9.2.3 Sample MADERAS-004
88
Table 9.30: Normal isochron table for MADERAS-004
Normal
Isochron
39(k)/36(a)
± 2σ
40(a+r)/36(a)
± 2σ
r.i.
BH5991
675 °C

6.3
± 0.1
296.3
± 3.0
0.7818
BH5992
720 °C

7.3
± 0.2
300.1
± 6.7
0.9415
BH5993
785 °C

15.4
± 0.3
300.7
± 4.8
0.9593
BH5994
830 °C

20.2
± 0.5
301.4
± 6.9
0.9740
BH5995
875 °C

35.0
± 0.6
305.8
± 5.0
0.9836
BH5996
925 °C

50.5
± 0.8
309.4
± 5.1
0.9831
BH5997
980 °C

49.3
± 0.5
308.7
± 3.4
0.9407
BH5998
1050 °C

24.6
± 0.4
301.3
± 4.8
0.9842
BH5999
1140 °C

8.6
± 0.1
297.2
± 1.7
0.5689
BH6000
1225 °C
5.2
± 0.1
295.5
± 2.8
0.8536
Results
40(a)/36(a)
Normal
Isochron
40(r)/39(k)
± 2σ
Age
± 2σ
294.9624
± 1.7393
± 0.59%
Statistical F ratio
2.01
Convergence
Error Magnification
1.0000
Number of Iterations
6
Number of Data Points
9
Calculated Line
Weighted York-2
0.2843
± 0.0705
136.5
± 24.79%
Minimal External Error
± 2σ
(Ka)
Analytical Error
Statistics
± 33.8
± 24.79%
± 34.3
MSWD
Table 9.30: Continued
0.23
± 33.8
0.0000000009
Table 9.31: Inverse isochron table for MADERAS-004
Inverse
Isochron
39(k)/40(a+r)
36(a)/40(a+r)
± 2σ
r.i.
± 2σ
BH5991
675 °C

0.021303
± 0.000163
0.003375
± 0.000034
0.0568
BH5992
720 °C

0.024171
± 0.000190
0.003332
± 0.000074
0.0420
BH5993
785 °C

0.051181
± 0.000239
0.003325
± 0.000053
0.0275
BH5994
830 °C

0.067141
± 0.000349
0.003318
± 0.000076
0.1212
BH5995
875 °C

0.114360
± 0.000340
0.003270
± 0.000054
0.1357
BH5996
925 °C

0.163266
± 0.000496
0.003232
± 0.000054
0.1112
BH5997
980 °C

0.159823
± 0.000607
0.003240
± 0.000035
0.1254
BH5998
1050 °C

0.081680
± 0.000233
0.003318
± 0.000053
0.0548
BH5999
1140 °C

BH6000
1225 °C
0.028927
± 0.000233
0.003365
± 0.000019
0.0265
0.017609
± 0.000098
0.003384
± 0.000032
0.0424
Results
Inverse
Isochron
Statistics
40(a)/36(a)
294.9699
40(r)/39(k)
± 2σ
± 0.8699
± 0.29%
0.2842
Age
± 2σ
± 0.0348
± 12.25%
136.5
± 2σ
(Ka)
± 16.7
± 12.25%
Minimal External Error
± 17.5
Analytical Error
± 16.7
MSW
D
Table 9.31: Continued
0.23
Statistical F ratio
2.01
Convergence
Error Magnification
1.0000
Number of Iterations
4
Number of Data Points
9
Calculated Line
Weighted York-2
89
0.0000000311
675°C
720°C
785°C
830°C
875°C
925°C
980°C
1050°C
1140°C
1225°C
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
Relative
Abundances
90

Σ








0.448
0.202
0.0270280
0.280
0.771
0.509
0.794
0.796
1.110
0.788
1.102
0.489
%1σ
0.0040873
0.0047498
0.0023519
0.0018965
0.0019168
0.0018151
0.0016077
0.0031172
0.0016962
0.0037895
36Ar
0.929
2.579
2.604
2.589
2.596
2.576
2.565
2.653
2.658
2.659
2.647
%1σ
0.0114814
0.0012287
0.0015734
0.0012030
0.0014983
0.0014591
0.0010414
0.0006670
0.0011987
0.0005368
0.0010750
38Ar
0.4811055
0.0210484
0.0405179
0.0565749
0.0906229
0.0942405
0.0622964
0.0321643
0.0475051
0.0122642
0.0238708
39Ar
0.061
0.264
0.398
0.118
0.151
0.095
0.074
0.177
0.222
0.369
0.368
%1σ
Table 9.32: Continued
0.764
1.470
0.956
3.248
2.238
2.071
2.290
4.816
2.371
3.094
2.774
%1σ
7.9868195
1.1833665
1.3960979
0.6907812
0.5660188
0.5763821
0.5439288
0.4782722
0.9263583
0.5065342
1.1190795
40Ar
Sample = MAD004
Material = groundmass
Location = UW93C44
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
IGSN = Undefined
Preferred Age = Undefined
Classification = Undefined
Experiment Type = Undefined
0.031
0.074
0.056
0.079
0.114
0.118
0.129
0.189
0.072
0.136
0.104
%1σ
0.0
94.9
114.1
128.3
131.9
141.2
139.0
162.7
303.4
59.1
Age
Extraction Method = Undefined
Heating = 900 sec
Isolation = 15.00 min
Instrument = MAP215
Lithology = Undefined
Lat-Lon = Undefined - Undefined
Age Equations = Conventional
Negative Intensities = Forced Zero
Decay Constant 40K = 5.463 ± 0.107 E-10 1/a
Decay Constant 39Ar = 2.940 ± 0.029 E-07 1/h
Decay Constant 37Ar = 8.230 ± 0.082 E-04 1/h
No 36Cl Correction
No 36Cl Correction
Information on Analysis and Constants Used in Calculations
1.6105274
0.3123914
0.1981247
0.2256117
0.2380724
0.2035477
0.1376659
0.0783120
0.1387339
0.0311651
0.0469027
37Ar
Table 9.32: Relative abundances for MADERAS-004
± 0.0
± 95.6
± 92.0
± 31.5
± 46.6
± 66.9
± 160.0
± 147.7
± 436.5
± 225.5
± 2σ
(Ka)
0.00
0.57
1.94
4.27
4.49
3.36
1.94
1.73
1.53
0.26
40Ar(r)
(%)
4.34
8.41
11.75
18.85
19.60
12.96
6.69
9.88
2.55
4.97
39Ar(k)
(%)
0.029
0.088
0.108
0.163
0.199
0.194
0.176
0.147
0.169
0.219
K/Ca
± 0.001
± 0.005
± 0.006
± 0.008
± 0.010
± 0.010
± 0.009
± 0.008
± 0.009
± 0.012
± 2σ
91
0.003777
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
Σ
Σ







0.46
0.21
0.026603
0.28
0.79
0.53
0.82
0.81
1.12
0.80
1.11
0.49
%1σ
0.004005
0.004698
0.002292
0.001834
0.001863
0.001779
0.001587
0.003081
0.001688
720 °C
BH5992

675 °C
BH5991

36Ar(a)
Degassing Patterns
0.2843
Normal
Isochron
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(c)
125.8
± 17.5
± 16.7
Analytical Error
± 16.7
± 12.25%
Minimal External Error
136.5
± 33.8
± 0.0348
± 12.25%
± 34.3
± 33.8
± 24.79%
± 30.9
Analytical Error
136.5
± 31.2
Minimal External Error
± 0.0705
± 24.79%
Analytical Error
Minimal External Error
± 30.9
± 24.53%
± 22.2
± 0.0643
± 24.53%
± 22.8
± 22.2
± 17.25%
± 2σ
(Ka)
Analytical Error
128.7
Age
Minimal External Error
± 0.0462
± 17.25%
± 2σ
1.0000
2.01
0.23
1.0000
2.01
0.23
1.0000
2.31
0.25
0.136
K/Ca
0.128
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000425
0.000082
0.000052
0.000060
0.000063
0.000054
0.000036
0.000021
0.000037
0.000008
0.000012
36Ar(ca)
0.93
2.58
2.60
2.59
2.60
2.58
2.56
2.65
2.66
2.66
2.65
%1σ
0.00
0.20
0.027028
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(cl)
1.610527
1.610527
0.312391
0.198125
0.225612
0.238072
0.203548
0.137666
0.078312
0.138734
0.031165
0.046903
37Ar(ca)
0.93
0.93
2.58
2.60
2.59
2.60
2.58
2.56
2.65
2.66
2.66
2.65
%1σ
± 0.002
± 0.031
± 2σ
0.004972
0.000748
0.000878
0.000428
0.000343
0.000348
0.000332
0.000297
0.000576
0.000315
0.000706
38Ar(a)
Error Magnification
Statistical F ratio
95.66
9
Error Magnification
Statistical F ratio
95.66
9
10
Error Magnification
Statistical T Ratio
95.66
9
39Ar(k)
(%,n)
Table 9.33: Degassing patterns for MADERAS-004
0.2842
0.2619
Total Fusion
Age
Inverse
Isochron
0.2680
40(r)/39(k)
Age Plateau
Results
Table 9.32: Continued
MSWD
0.21
0.46
0.28
0.79
0.53
0.82
0.81
1.12
0.80
1.11
0.49
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(c)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.005789
0.000251
0.000487
0.000680
0.001091
0.001135
0.000750
0.000387
0.000572
0.000148
0.000288
38Ar(k)
0.06
0.27
0.40
0.12
0.15
0.10
0.07
0.18
0.22
0.37
0.37
%1σ
92
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C









0.00
0.000000
Additional
Parameters
0.00
0.00
0.000000
0.000000
0.000000
0.00
0.00
0.000000
0.00
0.00
0.000000
0.000000
0.00
0.00
0.00
0.000000
0.000000
0.00
0.000000
0.000000
%1σ
38Ar(ca)
0.123182
0.631853
0.338786
0.289479
0.294104
0.274733
0.267125
0.237661
0.197743
0.000000
40(r)/39(k)
0.06
0.27
0.40
0.12
0.15
0.10
0.07
0.18
0.22
0.37
0.37
%1σ
0.481106
0.001084
0.000210
0.000133
0.000152
0.000160
0.000137
0.000093
0.000053
0.000093
0.000021
0.000032
39Ar(ca)
0.06
0.93
2.58
2.60
2.59
2.60
2.58
2.56
2.65
2.66
2.66
2.65
%1σ
0.125738
0.000000
0.007986
0.013410
0.024165
0.025853
0.018294
0.009296
0.016062
0.007736
0.002937
40Ar(r)
12.27
0.00
50.33
40.29
12.27
17.66
23.69
57.57
45.39
71.94
190.61
%1σ
7.861135
1.183420
1.388112
0.677372
0.541854
0.550529
0.525634
0.468977
0.910296
0.498798
1.116143
40Ar(a)
0.21
0.46
0.28
0.79
0.53
0.82
0.81
1.12
0.80
1.11
0.49
%1σ
1.119080
0.506534
0.926358
0.478272
0.543929
0.576382
0.566019
0.690781
1.396098
1.183367
40(r+a)
0.00117
0.00069
0.00067
0.00091
0.00070
0.00068
0.00065
0.00055
0.00078
0.00088
1σ
46.880699
41.301848
19.500191
14.869643
8.731300
6.116078
6.245866
12.210023
34.456287
56.221310
40Ar/39Ar
0.17940
0.16238
0.04550
0.03857
0.01297
0.00929
0.01184
0.01734
0.13844
0.15406
1σ
1.964859
2.541141
2.920401
2.434747
2.209852
2.159875
2.627065
3.987839
4.889800
14.841599
37Ar/39Ar
Table 9.34: Additional parameters for MADERAS-004
0.480022
0.020838
0.040385
0.056423
0.090463
0.094103
0.062204
0.032112
0.047412
0.012243
0.023839
39Ar(k)
0.23480
0.45458
0.15378
0.16667
0.06968
0.04852
0.03279
0.09576
0.09953
0.00000
1σ
0.63
9.04
0.000802
0.011564
8.04
7.37
41.66
52.02
0.00
0.00
0.00
56.28
23.06
36.83
%1σ
0.000229
0.000208
0.000094
0.000065
0.000000
0.000000
0.000000
0.000051
0.000074
0.000082
38Ar(cl)
Table 9.33: Continued
0.05250
0.06821
0.07790
0.06473
0.05671
0.05567
0.06832
0.10336
0.12880
0.38470
1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(c)
0.158751
0.138306
0.065617
0.049985
0.029137
0.020339
0.020928
0.041571
0.117227
0.194185
1σ
0.28
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.00097
0.00161
0.00054
0.00056
0.00023
0.00016
0.00011
0.00032
0.00057
0.00101
7.986873
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(k)
36Ar/39Ar
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
128.948
128.983
129.018
129.053
129.088
129.123
129.158
129.193
129.228
129.263
Time
(days)
93
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
Procedure
Blanks
0.000057
0.000057
0.000056
0.000056
0.000058
0.000060
0.000064
0.000069
0.000077
0.000085
36Ar
0.000008
0.000008
0.000008
0.000008
0.000008
0.000008
0.000008
0.000007
0.000007
0.000007
1σ
1.00091042
1.00091067
1.00091091
1.00091116
1.00091141
1.00091165
1.00091190
1.00091215
1.00091239
1.00091264
12.77373005
12.78266903
12.79143882
12.80021463
12.80917215
12.81796012
12.82675412
12.83573021
12.84453641
12.85334864
6.605E-15
2.990E-15
5.467E-15
2.823E-15
3.210E-15
3.402E-15
3.341E-15
4.077E-15
8.240E-15
6.984E-15
40Ar
(moles)
0.000001
0.000005
0.000012
0.000017
0.000023
0.000030
0.000039
0.000052
0.000069
0.000073
37Ar
0.000009
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
1σ
0.000011
0.000012
0.000014
0.000015
0.000016
0.000017
0.000018
0.000018
0.000015
0.000011
38Ar
0.000013
0.000013
0.000013
0.000013
0.000013
0.000013
0.000013
0.000012
0.000012
0.000012
1σ
0.000002
0.000005
0.000012
0.000021
0.000032
0.000043
0.000052
0.000050
0.000036
0.000037
39Ar
Table 9.35: Procedure Blanks for MADERAS-004
39Ar
(decay)
37Ar
(decay)
Table 9.34: Continued
0.000011
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000008
0.000008
0.000008
1σ
0.014875
0.015208
0.015465
0.015726
0.016054
0.016500
0.017087
0.017697
0.019719
0.022086
40Ar
0.000529
0.000576
0.000576
0.000576
0.000576
0.000576
0.000576
0.000527
0.000527
0.000527
1σ
94
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
Intercept
Values
675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
0.003924
0.001787
0.003237
0.001697
0.001910
0.002016
0.001999
0.002469
0.004923
0.004255
36Ar
0.023972
0.012320
0.047715
0.032320
0.062588
0.094676
0.091053
0.056861
0.040723
0.021173
39Ar
0.000017
0.000017
0.000024
0.000016
0.000012
0.000013
0.000006
0.000017
0.000010
0.000017
1σ
r2
8 of 8
8 of 8
8 of 8
6 of 8
8 of 8
6 of 8
8 of 8
7 of 8
7 of 8
8 of 8
0.9837
0.9763
0.9605
0.9861
0.9995
0.9991
0.9974
0.9962
0.8106
0.9960
EXP
LIN
EXP
LIN
EXP
LIN
EXP
LIN
EXP
LIN
0.000087
0.000044
0.000104
0.000055
0.000040
0.000085
0.000135
0.000064
0.000161
0.000055
1σ
0.9867
0.9209
0.9589
0.9388
0.9669
0.9784
0.9935
0.9720
0.9975
0.9887
r2
0.000025
0.000015
0.000082
0.000044
0.000026
0.000055
0.000088
0.000075
0.000078
0.000085
1σ
LIN
LIN
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
7 of 8
8 of 8
8 of 8
8 of 8
6 of 8
8 of 8
8 of 8
7 of 8
8 of 8
7 of 8
1.133954
0.521743
0.941823
0.493998
0.559983
0.592882
0.583106
0.708478
1.415817
1.205453
40Ar
r2
r2
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.9991
0.9995
0.9999
0.9979
0.9996
0.9996
0.9997
1.0000
0.9998
0.9997
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
0.001043
0.000375
0.000332
0.000699
0.000399
0.000364
0.000291
0.000141
0.000570
0.000702
1σ
0.9629
0.9646
0.9669
0.9596
0.9960
0.9926
0.9857
0.9860
0.9838
0.9908
Table 9.36: Continued
0.003729
0.002480
0.011023
0.006228
0.010934
0.016152
0.018883
0.017897
0.015729
0.024749
37Ar
Table 9.36: Intercept values for MADERAS-004
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
LIN
EXP
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
8 of 8
4 of 8
6 of 8
8 of 8
8 of 8
0.001097
0.000555
0.001225
0.000689
0.001068
0.001491
0.001532
0.001234
0.001605
0.001252
38Ar
0.000027
0.000011
0.000026
0.000030
0.000020
0.000028
0.000031
0.000038
0.000009
0.000014
1σ
0.4404
0.8599
0.6078
0.1010
0.2958
0.7244
0.7719
0.3378
0.8885
0.5297
r2
EXP
EXP
EXP
EXP
LIN
EXP
EXP
EXP
LIN
EXP
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
8 of 8
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
1
1
1
1
1
1
1
1
1
1
Volume
Ratio
675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
Sensitivity
(mol/volt)
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
5.902E-15
MAD004
MAD004
MAD004
MAD004
MAD004
MAD004
MAD004
MAD004
MAD004
MAD004
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
groundmass
Day
21
21
21
21
21
21
21
21
21
21
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
Month
2011
2011
2011
2011
2011
2011
2011
2011
2011
2011
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Brian Jicha
Analyst
675
720
785
830
875
925
980
1050
1140
1225
Temp
15
16
17
18
19
20
20
21
22
23
56
47
37
27
18
08
58
49
39
29
001
001
001
001
001
001
001
001
001
001
UW93
UW93
UW93
UW93
UW93
UW93
UW93
UW93
UW93
UW93
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
0.0002623
J
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
Experiment
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
%1σ
UW93C
UW93C
UW93C
UW93C
UW93C
UW93C
UW93C
UW93C
UW93C
UW93C
Project
Standard
(in Ma)
28.201
28.201
28.201
28.201
28.201
28.201
28.201
28.201
28.201
28.201
Irradiation
Table 9.37: Continued
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
UW93C44
Location
Year
Material
Hour
Sample
Min
Sample
Parameters
01
01
01
01
01
01
01
01
01
01
Nmb
Table 9.37: Sample parameters for MADERAS-004
Resist
95
1.005096
1.005096
1.005096
1.005096
1.005096
1.005096
1.005096
1.005096
1.005096
1.005096
MDF
FCS
FCS
FCS
FCS
FCS
FCS
FCS
FCS
FCS
FCS
Standard
Name
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
%1σ
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
%1σ
96
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
BH5991
BH5992
BH5993
BH5994
BH5995
BH5996
BH5997
BH5998
BH5999
BH6000
675 °C
720 °C
785 °C
830 °C
875 °C
925 °C
980 °C
1050 °C
1140 °C
1225 °C
40/36(a)
Irradiation
Constants
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0
0
0
0
0
0
0
0
0
0
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
38/36(c)
3
3
3
3
3
3
3
3
3
3
%1σ
0
0
0
0
0
0
0
0
0
0
%1σ
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
K/Ca
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
K/Cl
0
0
0
0
0
0
0
0
0
0
%1σ
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
39/37(ca)
Table 9.38: Continued
0
0
0
0
0
0
0
0
0
0
%1σ
36/38(cl)
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
38/36(a)
%1σ
35
35
35
35
35
35
35
35
35
35
%1σ
38/39(k)
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
40/36(c)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
38/37(ca)
Ca/Cl
0
0
0
0
0
0
0
0
0
0
%1σ
Table 9.38: Irradiation Constants for MADERAS-004
0
0
0
0
0
0
0
0
0
0
%1σ
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
36/37
(ca)
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
40/39
(k)
0
0
0
0
0
0
0
0
0
0
%1σ
UW93C44.AGE >>> MAD004 >>> UW93C PROJECT
1000
Ar-Ages in Ka
WEIGHTED PLATEAU
128.7 ± 22.2
TOTAL FUSION
125.8 ± 30.9
NORMAL ISOCHRON
136.5 ± 33.8
INVERSE ISOCHRON
136.5 ± 16.7
900
800
700
600
MSWD
0.25
500
400
128.7 ± 22.2 Ka
300
200
Sample Info
100
groundmass
UW93C44
Brian Jicha
0
IRR = UW93
J = 0.00026230 ± 0.00000013
100
200
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
Figure 9.9: Age plateau for MADERAS-004
UW93C44.AGE >>> MAD004 >>> UW93C PROJECT
0.33
Ar-Ages in Ka
WEIGHTED PLATEAU
128.7 ± 22.2
TOTAL FUSION
125.8 ± 30.9
NORMAL ISOCHRON
136.5 ± 33.8
INVERSE ISOCHRON
136.5 ± 16.7
0.30
0.27
0.23
0.136 ± 0.031
0.20
0.17
0.13
0.10
Sample Info
0.07
groundmass
UW93C44
Brian Jicha
IRR = UW93
J = 0.00026230 ± 0.00000013
0.03
0.00
0
10
20
30
40
50
60
Cumulative 39Ar Released [ % ]
Figure 9.10: K-Ca plateau for MADERAS-004
97
70
80
90
100
UW93C44.AGE >>> MAD004 >>> UW93C PROJECT
390
Ar-Ages in Ka
360
WEIGHTED PLATEAU
128.7 ± 22.2
TOTAL FUSION
125.8 ± 30.9
NORMAL ISOCHRON
136.5 ± 33.8
INVERSE ISOCHRON
136.5 ± 16.7
330
300
270
MSWD
0.23
240
210
40AR/36AR INTERCEPT
295.0 ± 1.7
180
150
120
Sample Info
groundmass
UW93C44
Brian Jicha
90
60
IRR = UW93
J = 0.00026230 ± 0.00000013
30
0
0
5
10
15
20
25
30
35
40
45
50
55
60
65
39Ar / 36Ar
Figure 9.11: Normal isochron for MADERAS-004
UW93C44.AGE >>> MAD004 >>> UW93C PROJECT
0.0045
Ar-Ages in Ka
WEIGHTED PLATEAU
128.7 ± 22.2
TOTAL FUSION
125.8 ± 30.9
NORMAL ISOCHRON
136.5 ± 33.8
INVERSE ISOCHRON
136.5 ± 16.7
0.0040
0.0035
0.0030
MSWD
0.23
0.0025
40AR/36AR INTERCEPT
295.0 ± 0.9
0.0020
0.0015
Sample Info
0.0010
groundmass
UW93C44
Brian Jicha
0.0005
IRR = UW93
J = 0.00026230 ± 0.00000013
0.0000
0.00
0.02
0.04
0.06
0.08
0.10
0.12
39Ar / 40Ar
Figure 9.12: Inverse isochron for MADERAS-004
98
0.14
0.16
0.18
0.20
1.208810
0.004679
Σ
Sample = MAD011
Material = groundmass
Location = UW93C47
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
Information
on Analysis
Total Fusion
Age
1.036544
0.015688
0.055832
0.125356
0.200783
0.212810
0.201707
0.114656
0.052357
0.057356
39Ar(k)
± 0.0128
± 3.47%
± 2σ
176.8
± 0.0179
± 4.90%
175.5
Minimal External Error
Analytical Error
0.3656
Minimal External Error
Analytical Error
0.3682
40(r)/39(k)
Age
0.378966
0.003512
0.019952
0.045482
0.073028
0.078861
0.073853
0.043542
0.020646
0.020090
40Ar(r)
Table 9.39: Continued
0.000514
0.000003
0.000000
0.000000
0.000000
0.000000
0.000000
0.000071
0.000170
0.000269
38Ar(cl)
Age Plateau
Results
0.023019
0.070093
0.121757
0.166247
0.157022
0.187143
0.161520
0.106418
0.215592
0.000124
0.000228
0.000309
0.000444
0.000377
0.000495
0.000590
0.000744
0.001367









740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
37Ar(ca)
36Ar(a)
Incremental
Heating
± 11.0
± 8.6
± 8.6
± 4.90%
± 9.2
± 6.1
± 6.1
± 3.47%
± 2σ
(Ka)
± 2σ
(Ka)
107.5 ± 166.0
171.6 ± 44.8
174.2 ± 21.9
174.6 ± 12.5
177.9 ± 9.4
175.8 ± 17.5
182.3 ± 19.5
189.3 ± 80.2
168.2 ± 64.2
Age
Table 9.39: Incremental heating summary for MADERAS-011
0.212
9
0.369
± 0.018
± 0.018
± 0.024
± 0.028
± 0.031
± 0.024
± 0.016
± 0.011
± 0.006
± 2σ
± 0.007
± 0.091
± 2σ
0.293
0.343
0.443
0.519
0.583
0.463
0.305
0.212
0.114
K/Ca
Statistical T Ratio
Error Magnification
100.00
9
K/Ca
39Ar(k)
(%)
1.51
5.39
12.09
19.37
20.53
19.46
11.06
5.05
5.53
39Ar(k)
(%,n)
40Ar(r)
(%)
8.73
22.87
33.23
35.77
41.42
33.53
19.98
8.58
4.74
2.31
1.0000
0.19
MSW
D
9.2.4 Sample MADERAS-011
99
Table 9.40: Normal Isochron Table for MADERAS-011
Normal
Isochron
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
39(k)/36(a)
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
126.2
245.3
405.3
452.5
563.8
407.2
194.3
70.3
42.0









± 2σ
40(a+r)/36(a)
± 18.5
± 18.7
± 25.1
± 17.9
± 20.8
± 20.4
± 5.1
± 2.8
± 0.8
323.8
383.1
442.5
460.1
504.4
444.6
369.3
323.2
310.2
r.i.
± 2σ
± 47.8
± 29.4
± 27.5
± 18.2
± 18.6
± 22.3
± 9.8
± 12.8
± 5.9
0.9914
0.9895
0.9935
0.9890
0.9923
0.9958
0.9786
0.9884
0.9409
Results
40(a)/36(a)
Normal
Isochron
295.4061
40(r)/39(k)
± 2σ
± 5.2321
± 1.77%
0.3683
Age
± 2σ
± 0.0189
± 5.14%
176.8
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
2.01
1.0000
9
Convergence
Number of Iterations
Calculated Line
MSW
D
Table 9.40: Continued
± 2σ
(Ka)
± 9.1
± 5.14%
0.23
± 11.4
± 9.1
0.0000000023
17
Weighted York-2
Table 9.41: Inverse isochron table for MADERAS-011
Inverse
Isochron
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
39(k)/40(a+r)
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C









0.389861
0.640108
0.915773
0.983482
1.117656
0.915842
0.526070
0.217620
0.135291
36(a)/40(a+r)
± 2σ
± 0.007511
± 0.007115
± 0.006475
± 0.005769
± 0.005116
± 0.004224
± 0.002881
± 0.001314
± 0.000909
0.003089
0.002610
0.002260
0.002174
0.001983
0.002249
0.002708
0.003094
0.003224
r.i.
± 2σ
± 0.000456
± 0.000201
± 0.000140
± 0.000086
± 0.000073
± 0.000113
± 0.000072
± 0.000123
± 0.000061
0.1058
0.1346
0.0960
0.0831
0.0711
0.0447
0.1231
0.0814
0.0462
Results
Inverse
Isochron
40(a)/36(a)
295.4567
± 2σ
± 2.6172
± 0.89%
40(r)/39(k)
0.3683
Age
± 2σ
± 0.0095
± 2.57%
176.8
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
2.01
1.0000
9
Convergence
Number of Iterations
Calculated Line
100
± 2σ
(Ka)
± 4.5
± 2.57%
MSWD
Table 9.41: Continued
0.21
± 8.3
± 4.5
0.0000013935
4
Weighted York-2
101
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6064
BH6065
BH6066
BH6067
BH6068
850 °C
900 °C
BH6062
800 °C
BH6061
BH6063
740 °C
BH6060
Relative
Abundances
0.896
0.619
0.0049982
Σ
1.898
1.207
2.260
1.636
1.775
2.785
3.514
6.981
0.0014236
0.0007724
0.0006328
0.0005448
0.0004189
0.0004876
0.0003415
0.0002462
0.0001304
%1σ









36Ar
0.961
2.653
2.671
2.668
2.631
2.655
2.653
2.660
2.668
3.000
%1σ
0.584
2.367
2.162
2.054
0.458
1.550
1.198
1.053
4.774
5.827
%1σ
1.0373580
0.0575008
0.0524285
0.1147644
0.2018334
0.2129156
0.2008952
0.1254375
0.0558793
0.0157033
39Ar
0.067
0.313
0.206
0.174
0.165
0.149
0.194
0.140
0.146
0.420
%1σ
Table 9.42: Continued
0.0134175
0.0012159
0.0009406
0.0015643
0.0025164
0.0025520
0.0023439
0.0014062
0.0006623
0.0002159
38Ar
1.7616334
0.4239441
0.2405887
0.2179478
0.2202427
0.1904073
0.2041555
0.1368849
0.0872230
0.0402394
40Ar
Sample = MAD011
Material = groundmass
Location = UW93C47
Analyst = Brian Jicha
Project = UW93C
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00026230 ± 0.00000013
FCS = 28.201 ± 0.023 Ma
IGSN = Undefined
Preferred Age = Undefined
Classification = Undefined
Experiment Type = Undefined
0.075
0.121
0.221
0.211
0.161
0.173
0.220
0.325
0.536
0.867
%1σ
168.2
189.3
182.3
175.8
177.9
174.6
174.2
171.6
107.5
Age
± 64.2
± 80.2
± 19.5
± 17.5
± 9.4
± 12.5
± 21.9
± 44.8
± 166.0
± 2σ
(Ka)
Extraction Method = Undefined
Heating = 900 sec
Isolation = 15.00 min
Instrument = MAP215
Lithology = Undefined
Lat-Lon = Undefined - Undefined
Age Equations = Conventional
Negative Intensities = Forced Zero
Decay Constant 40K = 5.463 ± 0.107 E-10 1/a
Decay Constant 39Ar = 2.940 ± 0.029 E-07 1/h
Decay Constant 37Ar = 8.230 ± 0.082 E-04 1/h
No 36Cl Correction
No 36Cl Correction
Information on Analysis and Constants Used in Calculations
1.2088104
0.2155921
0.1064180
0.1615197
0.1871433
0.1570217
0.1662465
0.1217569
0.0700931
0.0230192
37Ar
Table 9.42: Relative abundances for MADERAS-011
4.74
8.58
19.98
33.53
41.42
35.77
33.23
22.87
8.73
40Ar(r)
(%)
5.53
5.05
11.06
19.46
20.53
19.37
12.09
5.39
1.51
39Ar(k)
(%)
0.114
0.212
0.305
0.463
0.583
0.519
0.443
0.343
0.293
K/Ca
± 0.006
± 0.011
± 0.016
± 0.024
± 0.031
± 0.028
± 0.024
± 0.018
± 0.018
± 2σ
102
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6064
BH6065
BH6066
BH6067
BH6068
850 °C
900 °C
BH6062
BH6063

0.000309
3.09
0.66
0.004679
Σ
Σ
0.94
1.97
1.31
2.50
1.84
1.97
0.001367
0.000744
0.000590
0.000495
0.000377
0.000444
3.81
7.32
%1σ






0.000228
0.000124
800 °C
BH6061

740 °C
BH6060

36Ar(a)
Degassing
Patterns
Inverse
Isochron
Normal
Isochron
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(c)
Total Fusion
Age
Age Plateau
Results
± 0.0128
± 3.47%
± 2σ
176.8
Age
± 0.0095
± 2.57%
± 0.0189
± 5.14%
176.8
176.8
± 8.3
± 4.5
± 4.5
± 2.57%
2.01
1.0000
0.21
2.01
1.0000
0.23
2.31
1.0000
0.19
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000319
0.000057
0.000028
0.000043
0.000049
0.000041
0.000044
0.000032
0.000019
0.000006
36Ar(ca)
0.96
2.65
2.67
2.67
2.63
2.66
2.65
2.66
2.67
3.00
%1σ
0.00
0.63
0.004998
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(cl)
1.208810
1.208810
0.215592
0.106418
0.161520
0.187143
0.157022
0.166247
0.121757
0.070093
0.023019
37Ar(ca)
0.212
K/Ca
0.369
0.96
0.96
2.65
2.67
2.67
2.63
2.66
2.65
2.66
2.67
3.00
%1σ
0.000875
0.000255
0.000139
0.000110
0.000093
0.000071
0.000083
0.000058
0.000043
0.000023
38Ar(a)
0.66
0.94
1.97
1.31
2.50
1.84
1.97
3.09
3.81
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(c)
± 0.007
± 0.091
± 2σ
7.32
%1σ
Statistical F ratio
Error Magnification
100.00
9
Statistical F ratio
Error Magnification
100.00
9
9
Statistical T Ratio
Error Magnification
100.00
9
39Ar(k)
(%,n)
Table 9.43: Degassing patterns for MADERAS-011
Minimal External Error
Analytical Error
0.3683
0.3683
± 11.4
± 9.1
± 8.6
± 4.90%
Minimal External Error
Analytical Error
175.5
± 11.0
± 8.6
± 9.1
± 5.14%
± 0.0179
± 4.90%
± 9.2
± 6.1
± 6.1
± 3.47%
± 2σ
(Ka)
Minimal External Error
Analytical Error
0.3656
Minimal External Error
Analytical Error
0.3682
40(r)/39(k)
Table 9.42: Continued
MSW
D
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.012501
0.000692
0.000631
0.001383
0.002433
0.002566
0.002421
0.001512
0.000673
0.000189
38Ar(k)
0.07
0.31
0.21
0.17
0.17
0.15
0.19
0.14
0.15
0.42
%1σ
103
0.00
0.00
0.000000
0.000000
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068







0.350266
0.394336
0.379760
0.366137
0.370568
0.363718
0.362828
0.357353
0.223878
740 °C
BH6060

40(r)/39(k)
Additional
Parameters

0.00
0.00
0.000000
0.000000
0.00
0.00
0.000000
0.000000
0.00
0.00
0.00
0.000000
0.000000
0.00
0.000000
0.000000
%1σ
38Ar(ca)
0.06682
0.08348
0.02031
0.01823
0.00978
0.01307
0.02279
0.04661
0.17289
0.423944
0.240589
0.217948
0.220243
0.190407
0.204156
0.136885
0.087223
0.07
0.31
0.21
0.17
0.17
0.15
0.19
0.14
0.15
0.42
%1σ
1.037358
0.000814
0.000145
0.000072
0.000109
0.000126
0.000106
0.000112
0.000082
0.000047
0.000015
39Ar(ca)
0.07
0.96
2.65
2.67
2.67
2.63
2.66
2.65
2.66
2.67
3.00
%1σ
0.378966
0.020090
0.020646
0.043542
0.073853
0.078861
0.073028
0.045482
0.019952
0.003512
40Ar(r)
2.45
19.07
21.17
5.35
4.98
2.64
3.59
6.28
13.04
77.22
%1σ
1.382668
0.403854
0.219943
0.174406
0.146390
0.111547
0.131127
0.091402
0.067271
0.036727
40Ar(a)
0.00051
0.00053
0.00046
0.00035
0.00033
0.00045
0.00044
0.00047
0.00035
1σ
7.372838
4.588895
1.899089
1.091210
0.894285
1.016229
1.091260
1.560917
2.562486
40Ar/39Ar
0.02472
0.01384
0.00520
0.00252
0.00205
0.00298
0.00386
0.00867
0.02468
1σ
3.749374
2.029775
1.407403
0.927217
0.737483
0.827529
0.970658
1.254365
1.465886
37Ar/39Ar
0.10016
0.05438
0.03764
0.02444
0.01961
0.02201
0.02585
0.03352
0.04440
1σ
0.024758
0.014732
0.005514
0.002699
0.001968
0.002427
0.002722
0.004405
0.008302
36Ar/39Ar
1σ
0.00024
0.00028
0.00007
0.00006
0.00003
0.00004
0.00008
0.00015
132.301
132.265
132.231
132.196
132.160
132.126
132.091
132.056
132.021
Time
(days)
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(c)
0.00058
0.66
0.94
1.97
1.31
2.50
1.84
1.97
3.09
3.81
7.32
%1σ
Table 9.44: Additional parameters for MADERAS-011
1.036544
0.057356
0.052357
0.114656
0.201707
0.212810
0.200783
0.125356
0.055832
0.015688
39Ar(k)
0.040239
40(r+a)
0.36
0.013889
1σ
9.67
10.78
12.09
45.26
0.00
0.00
0.00
0.00
0.00
370.21
%1σ
0.000514
0.000269
0.000170
0.000071
0.000000
0.000000
0.000000
0.000000
0.000000
0.000003
38Ar(cl)
Table 9.43: Continued
37Ar
(decay)
1.761633
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(k)
13.64829750
13.63875317
13.62940247
13.62005817
13.61053359
13.60120223
13.59187727
13.58237240
13.57306035
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
1.00093410
1.00093385
1.00093360
1.00093336
1.00093311
1.00093286
1.00093262
1.00093237
1.00093212
39Ar
(decay)
0.74
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
2.502E-15
1.420E-15
1.286E-15
1.300E-15
1.124E-15
1.205E-15
8.079E-16
5.148E-16
2.375E-16
40Ar
(moles)
104
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
Intercept
Values
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
0.000176
0.000295
0.000394
0.000544
0.000475
0.000604
0.000695
0.000839
0.001505
36Ar
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
Procedure
Blanks
0.000007
0.000007
0.000008
0.000007
0.000004
0.000011
0.000005
0.000014
0.000011
1σ
0.000043
0.000044
0.000045
0.000046
0.000047
0.000048
0.000050
0.000051
0.000052
36Ar
0.4193
0.8020
0.8100
0.8828
0.9331
0.5302
0.9454
0.8368
0.9826
r2
0.000006
0.000008
0.000009
0.000011
0.000014
0.000017
0.000021
0.000026
0.000031
37Ar
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
1σ
0.000027
0.000022
0.000019
0.000017
0.000015
0.000013
0.000013
0.000014
0.000016
38Ar
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
0.000009
1σ
EXP
EXP
EXP
EXP
EXP
EXP
LIN
LIN
PAR
8 of 8
8 of 8
8 of 8
8 of 8
6 of 8
8 of 8
8 of 8
8 of 8
6 of 8
0.001728
0.005248
0.009106
0.012423
0.011728
0.013969
0.012055
0.007949
0.016071
37Ar
0.000023
0.000027
0.000045
0.000057
0.000055
0.000041
0.000064
0.000042
0.000071
1σ
0.8901
0.9839
0.9849
0.9887
0.9850
0.9945
0.9844
0.9847
0.9891
r2
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
39Ar
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.000017
0.000017
0.000017
0.000018
0.000019
0.000021
0.000023
0.000027
0.000031
Table 9.46: Intercept values for MADERAS-011
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
1σ
Table 9.45: Procedure Blanks for MADERAS-011
0.000245
0.000692
0.001440
0.002385
0.002593
0.002556
0.001593
0.000964
0.001244
38Ar
0.000014
0.000014
0.000014
0.000014
0.000014
0.000014
0.000014
0.000014
0.000014
1σ
0.000009
0.000031
0.000012
0.000027
0.000039
0.000007
0.000031
0.000018
0.000028
1σ
0.013242
0.013650
0.013990
0.014330
0.014670
0.015078
0.015554
0.016098
0.016540
40Ar
0.7094
0.3005
0.9450
0.8981
0.8274
0.9960
0.6417
0.8496
0.7076
r2
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
0.000329
0.000329
0.000329
0.000329
0.000329
0.000329
0.000329
0.000329
0.000329
1σ
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
Table 9.46: Continued
39Ar
1σ
r2
0.015786
0.056131
0.125982
0.201758
0.213829
0.202702
0.115270
0.052676
0.057773
0.000065
0.000079
0.000172
0.000387
0.000313
0.000329
0.000197
0.000106
0.000179
0.9760
0.9988
0.9987
0.9975
0.9985
0.9981
0.9979
0.9967
0.9872
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
LIN
6 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
40Ar
1σ
r2
0.053481
0.100873
0.150875
0.218485
0.205077
0.235321
0.233502
0.256687
0.440484
0.000116
0.000333
0.000299
0.000305
0.000029
0.000131
0.000323
0.000417
0.000395
0.9823
0.9876
0.9943
0.9973
1.0000
0.9997
0.9978
0.9977
0.9993
EXP
PAR
EXP
EXP
EXP
EXP
EXP
EXP
EXP
8 of 8
8 of 8
8 of 8
8 of 8
4 of 8
7 of 8
8 of 8
7 of 8
4 of 8
Sample
Parameters
Sample
Material
Location
Temp
Table 9.47: Sample parameters for MADERAS-011
Analyst
Standard
(in Ma)
%1σ
J
%1σ
BH6060
740 °C
MAD011
groundmass
UW93C47
Brian Jicha
740
28.201
0.08
0.0002623
0.05
BH6061
800 °C
MAD011
groundmass
UW93C47
Brian Jicha
800
28.201
0.08
0.0002623
0.05
BH6062
850 °C
MAD011
groundmass
UW93C47
Brian Jicha
850
28.201
0.08
0.0002623
0.05
BH6063
900 °C
MAD011
groundmass
UW93C47
Brian Jicha
900
28.201
0.08
0.0002623
0.05
BH6064
950 °C
MAD011
groundmass
UW93C47
Brian Jicha
950
28.201
0.08
0.0002623
0.05
BH6065
1010 °C
MAD011
groundmass
UW93C47
Brian Jicha
1010
28.201
0.08
0.0002623
0.05
BH6066
1080 °C
MAD011
groundmass
UW93C47
Brian Jicha
1080
28.201
0.08
0.0002623
0.05
BH6067
1160 °C
MAD011
groundmass
UW93C47
Brian Jicha
1160
28.201
0.08
0.0002623
0.05
BH6068
1225 °C
MAD011
groundmass
UW93C47
Brian Jicha
1225
28.201
0.08
0.0002623
0.05
Sensitivity
(mol/volt)
Hour
Irradia
tion
Project
Experimen
t
Nmb
Volu
me
Ratio
Year
Resist
%1σ
Month
Min
MDF
Day
Table 9.47: Continued
Stand
ard
Name
1.00515
0.03
1
5.902E-15
24
OCT
2011
17
1.00515
0.03
1
5.902E-15
24
OCT
2011
18
31
41
001
UW93
UW93C
UW93C47
01
FCS
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
5.902E-15
24
OCT
2011
19
FCS
22
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
5.902E-15
24
OCT
2011
FCS
20
12
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
5.902E-15
24
OCT
FCS
2011
21
02
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
5.902E-15
24
FCS
OCT
2011
21
53
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
5.902E-15
FCS
24
OCT
2011
22
43
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
FCS
5.902E-15
24
OCT
2011
23
33
001
UW93
UW93C
UW93C47
01
1.00515
0.03
1
FCS
5.902E-15
25
OCT
2011
00
24
001
UW93
UW93C
UW93C47
01
FCS
105
106
BH6060
BH6061
BH6062
BH6063
BH6064
BH6065
BH6066
BH6067
BH6068
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
Irradiation
Constants
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
35
35
35
35
35
35
35
35
35
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
38/36(c)
0
0
0
0
0
0
0
0
0
36/38(cl)
0
0
0
0
0
0
0
0
0
%1σ
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
K/Ca
Table 9.48: Continued
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
38/36(a)
%1σ
%1σ
38/39(k)
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
40/36(c)
%1σ
%1σ
40/39(k)
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
40/36(a)
0
0
0
0
0
0
0
0
0
%1σ
3
3
3
3
3
3
3
3
3
%1σ
0
0
0
0
0
0
0
0
0
K/Cl
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
38/37(ca)
Ca/Cl
%1σ
%1σ
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
39/37(ca)
Table 9.48: Irradiation constants for MADERAS-011
0
0
0
0
0
0
0
0
0
%1σ
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
36/37(ca)
0
0
0
0
0
0
0
0
0
%1σ
UW93C47.AGE >>> MAD011 >>> UW93C PROJECT
400
Ar-Ages in Ka
WEIGHTED PLATEAU
176.8 ± 6.1
TOTAL FUSION
175.5 ± 8.6
NORMAL ISOCHRON
176.8 ± 9.1
INVERSE ISOCHRON
176.8 ± 4.5
350
300
250
MSWD
0.19
200
150
176.8 ± 6.1 Ka
100
Sample Info
groundmass
UW93C47
Brian Jicha
50
0
IRR = UW93
J = 0.00026230 ± 0.00000013
50
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
Figure 9.13: Age plateau for MADERAS-011
UW93C47.AGE >>> MAD011 >>> UW93C PROJECT
0.9
Ar-Ages in Ka
WEIGHTED PLATEAU
176.8 ± 6.1
TOTAL FUSION
175.5 ± 8.6
NORMAL ISOCHRON
176.8 ± 9.1
INVERSE ISOCHRON
176.8 ± 4.5
0.8
0.7
0.6
0.5
0.212 ± 0.091
0.4
0.3
Sample Info
0.2
groundmass
UW93C47
Brian Jicha
0.1
IRR = UW93
J = 0.00026230 ± 0.00000013
0.0
0
10
20
30
40
50
60
Cumulative 39Ar Released [ % ]
Figure 9.14: K-Ca plateau for MADERAS-011
107
70
80
90
100
UW93C47.AGE >>> MAD011 >>> UW93C PROJECT
650
Ar-Ages in Ka
600
WEIGHTED PLATEAU
176.8 ± 6.1
TOTAL FUSION
175.5 ± 8.6
NORMAL ISOCHRON
176.8 ± 9.1
INVERSE ISOCHRON
176.8 ± 4.5
550
500
450
MSWD
0.23
400
350
40AR/36AR INTERCEPT
295.4 ± 5.2
300
250
200
Sample Info
150
groundmass
UW93C47
Brian Jicha
100
IRR = UW93
J = 0.00026230 ± 0.00000013
50
0
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
39Ar / 36Ar
Figure 9.15: Normal isochron for MADERAS-011
UW93C47.AGE >>> MAD011 >>> UW93C PROJECT
0.0045
Ar-Ages in Ka
WEIGHTED PLATEAU
176.8 ± 6.1
TOTAL FUSION
175.5 ± 8.6
NORMAL ISOCHRON
176.8 ± 9.1
INVERSE ISOCHRON
176.8 ± 4.5
0.0040
0.0035
0.0030
MSWD
0.21
0.0025
40AR/36AR INTERCEPT
295.5 ± 2.6
0.0020
0.0015
Sample Info
0.0010
groundmass
UW93C47
Brian Jicha
0.0005
IRR = UW93
J = 0.00026230 ± 0.00000013
0.0000
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
39Ar / 40Ar
Figure 9.16: Inverse isochron for MADERAS-011
108
2.4
2.7
3.0
3.3
0.430396
0.006925
Σ
Sample = MAD013
Material = groundmass
Location = UW93D48
Analyst = Brian Jicha
Project = UW93D
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00025540 ± 0.00000020
FCS = 28.201 ± 0.023 Ma
Information
on Analysis
Total Fusion
Age
1.880961
0.030385
0.091692
0.345378
0.455868
0.429796
0.229797
0.184179
0.096197
0.015894
0.001776
39Ar(k)
± 0.0067
± 3.69%
± 2σ
85.2
± 0.0101
± 5.56%
85.1
Minimal External Error
Analytical Error
0.1820
Minimal External Error
Analytical Error
0.1822
40(r)/39(k)
Age
0.342396
0.006506
0.018062
0.062318
0.084735
0.076329
0.042019
0.034426
0.013979
0.002811
0.001211
40Ar(r)
Table 9.49: Continued
0.000595
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000388
0.000176
0.000027
0.000004
38Ar(cl)
Age Plateau
Results
0.005627
0.015823
0.057805
0.081124
0.086342
0.063424
0.052180
0.035448
0.024601
0.008022
0.000044
0.000109
0.000280
0.000341
0.000453
0.000641
0.001543
0.001969
0.001355
0.000192










675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
37Ar(ca)
36Ar(a)
Incremental
Heating
± 2σ
(Ka)
± 68.1
± 27.4
± 8.0
± 5.8
± 5.5
± 9.7
± 10.0
± 48.6
± 213.4
± 1451.1
± 5.8
± 4.7
± 4.7
± 5.56%
± 4.6
± 3.1
± 3.1
± 3.70%
± 2σ
(Ka)
100.1
92.1
84.4
86.9
83.0
85.5
87.4
67.9
82.7
318.9
Age
Table 9.49: Incremental heating summary for MADERAS-013
2.26
1.0000
0.25
MSW
D
9.2.5 Sample MADERAS-013
109
0.19
± 0.22
± 2σ
2.32
2.49
2.57
2.42
2.14
1.56
1.52
1.17
0.28
0.10
K/Ca
10
1.88
± 0.04
Statistical T Ratio
Error Magnification
100.00
10
K/Ca
39Ar(k)
(%)
1.62
4.87
18.36
24.24
22.85
12.22
9.79
5.11
0.85
0.09
39Ar(k)
(%,n)
40Ar(r)
(%)
33.16
35.99
43.00
45.71
36.31
18.16
7.02
2.35
0.70
2.09
± 0.25
± 0.16
± 0.14
± 0.13
± 0.11
± 0.09
± 0.08
± 0.07
± 0.02
± 0.01
± 2σ
Table 9.50: Normal isochron table for MADERAS-013
Normal
Isochron
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
39(k)/36(a)
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
684.8
843.3
1235.4
1338.7
948.5
358.6
119.4
48.9
11.7
9.2










40(a+r)/36(a)
± 2σ
± 231.0
± 141.0
± 87.9
± 74.9
± 36.0
± 9.0
± 1.1
± 0.8
± 0.2
± 0.9
442.1
461.6
518.4
544.3
463.9
361.1
317.8
302.6
297.6
301.8
r.i.
± 2σ
± 149.2
± 77.2
± 36.9
± 30.5
± 17.6
± 9.0
± 2.7
± 5.2
± 5.4
± 29.3
0.9997
0.9995
0.9995
0.9990
0.9983
0.9926
0.9413
0.9921
0.9250
0.9731
Table 9.50: Continued
40(a)/36(a)
Normal
Isochron
295.5822
40(r)/39(k)
± 2σ
± 2.3714
± 0.80%
0.1818
Age
± 2σ
± 0.0082
± 4.49%
85.0
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
1.94
1.0000
10
Convergence
Number of Iterations
Calculated Line
± 2σ
(Ka)
MSW
D
Results
± 3.8
± 4.49%
0.28
± 5.1
± 3.8
0.0000000018
21
Weighted York-2
Table 9.51: Inverse isochron table for MADERAS-013
Inverse
Isochron
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
39(k)/40(a+r)
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C










1.548944
1.826888
2.383012
2.459332
2.044369
0.993136
0.375695
0.161492
0.039432
0.030619
36(a)/40(a+r)
± 2σ
± 0.013157
± 0.009483
± 0.005496
± 0.006094
± 0.004511
± 0.003036
± 0.001136
± 0.000351
± 0.000291
± 0.000702
0.002262
0.002166
0.001929
0.001837
0.002155
0.002770
0.003146
0.003305
0.003360
0.003313
r.i.
± 2σ
± 0.000763
± 0.000362
± 0.000137
± 0.000103
± 0.000082
± 0.000069
± 0.000027
± 0.000057
± 0.000061
± 0.000322
0.0183
0.0183
0.0207
0.0297
0.0290
0.0412
0.0680
0.0131
0.0218
0.0088
Results
Inverse
Isochron
40(a)/36(a)
295.5736
± 2σ
± 1.1856
± 0.40%
40(r)/39(k)
0.1820
Age
± 2σ
± 0.0041
± 2.24%
85.1
Minimal External Error
Analytical Error
Statistics
Statistical F ratio
Error Magnification
Number of Data Points
1.94
1.0000
10
Convergence
Number of Iterations
Calculated Line
110
± 2σ
(Ka)
± 1.9
± 2.24%
MSW
D
Table 9.51: Continued
0.28
± 3.8
± 1.9
0.0000000220
4
Weighted York-2
111
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
Relative
Abundances

4.796
0.456
0.0070385
Σ
0.898
0.855
0.421
1.214
1.800
2.626
3.372
8.047
16.316
0.0001943
0.0013610
0.0019779
0.0015563
0.0006576
0.0004759
0.0003620
0.0002948
0.0001129
0.0000459
%1σ









36Ar
1.031
4.179
3.035
2.887
2.782
2.753
2.662
2.691
2.692
3.226
5.323
%1σ
0.500
28.566
6.707
2.839
1.115
1.285
1.157
1.036
0.683
1.630
5.975
%1σ
1.8812509
0.0017810
0.0159109
0.0962205
0.1842142
0.2298392
0.4298543
0.4559231
0.3454171
0.0917022
0.0303883
39Ar
0.036
1.122
0.359
0.103
0.136
0.124
0.078
0.071
0.069
0.166
0.222
%1σ
Table 9.52: Continued
0.0238877
0.0000618
0.0004714
0.0017038
0.0028978
0.0028498
0.0052352
0.0053339
0.0038727
0.0010900
0.0003713
38Ar
0.0196163
Sample = MAD013
Material = groundmass
Location = UW93D48
Analyst = Brian Jicha
Project = UW93D
Mass Discrimination Law = LIN
Irradiation = UW93
J = 0.00025540 ± 0.00000020
FCS = 28.201 ± 0.023 Ma
IGSN = Undefined
Preferred Age = Undefined
Classification = Undefined
Experiment Type = Undefined
40Ar
2.3887025
0.0579916
0.4030797
0.5956734
0.4902363
0.2313849
0.2102341
0.1853628
0.1449334
0.0501900
0.027
0.222
0.085
0.035
0.067
0.089
0.078
0.101
0.092
0.199
0.362
%1σ
318.9
82.7
67.9
87.4
85.5
83.0
86.9
84.4
92.1
100.1
Age
Extraction Method = Undefined
Heating = 900 sec
Isolation = 15.00 min
Instrument = MAP215
Lithology = Undefined
Lat-Lon = Undefined - Undefined
Age Equations = Conventional
Negative Intensities = Forced Zero
Decay Constant 40K = 5.463 ± 0.107 E-10 1/a
Decay Constant 39Ar = 2.940 ± 0.029 E-07 1/h
Decay Constant 37Ar = 8.230 ± 0.082 E-04 1/h
No 36Cl Correction
No 36Cl Correction
Information on Analysis and Constants Used in Calculations
0.4303958
0.0080224
0.0246008
0.0354480
0.0521797
0.0634241
0.0863417
0.0811242
0.0578049
0.0158226
0.0056274
37Ar
Table 9.52: Relative abundances for MADERAS-013
± 1451.1
± 213.4
± 48.6
± 10.0
± 9.7
± 5.5
± 5.8
± 8.0
± 27.4
± 68.1
± 2σ
(Ka)
2.09
0.70
2.35
7.02
18.16
36.31
45.71
43.00
35.99
33.16
40Ar(r)
(%)
0.09
0.85
5.11
9.79
12.22
22.85
24.24
18.36
4.87
1.62
39Ar(k)
(%)
0.10
0.28
1.17
1.52
1.56
2.14
2.42
2.57
2.49
2.32
K/Ca
± 0.01
± 0.02
± 0.07
± 0.08
± 0.09
± 0.11
± 0.13
± 0.14
± 0.16
± 0.25
± 2σ
112
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
800 °C
850 °C
BH6078
BH6079

0.000280
0.46
0.006925
Σ
Σ
4.85
0.90
0.86
0.43
1.25
1.90
2.80
3.56
8.36
16.86
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(c)
± 0.0041 85.1
± 2.24%
Minimal External Error
Analytical Error
Inverse
Isochron
%1σ
± 0.0082 85.0
± 4.49%
Minimal External Error
Analytical Error
± 1.9
± 2.24%
± 3.8
± 1.9
± 4.7
± 5.56%
± 5.8
± 4.7
± 3.8
± 4.49%
± 5.1
± 3.8
± 3.1
± 3.70%
± 4.6
± 3.1
± 2σ
(Ka)
1.94
1.0000
0.28
1.94
1.0000
0.28
2.26
1.0000
0.25
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000114
0.000002
0.000006
0.000009
0.000014
0.000017
0.000023
0.000021
0.000015
0.000004
0.000001
36Ar(ca)
1.03
4.18
3.03
2.89
2.78
2.75
2.66
2.69
2.69
3.23
5.32
%1σ
0.00
0.46
0.007039
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
36Ar(cl)
0.430396
0.430396
0.008022
0.024601
0.035448
0.052180
0.063424
0.086342
0.081124
0.057805
0.015823
0.005627
37Ar(ca)
K/Ca
± 2σ
1.88
± 0.04
1.03
1.03
4.18
3.03
2.89
2.78
2.75
2.66
2.69
2.69
3.23
5.32
%1σ
0.001294
0.000036
0.000253
0.000368
0.000288
0.000120
0.000085
0.000064
0.000052
0.000020
0.000008
38Ar(a)
0.46
4.85
0.90
0.86
0.43
1.25
1.90
2.80
3.56
8.36
16.86
%1σ
100.00
10
Statistical F ratio
Error Magnification
100.00
10
Statistical F ratio
Error Magnification
10
100.00
0.19 ± 0.22
10
Statistical T Ratio
Error Magnification
39Ar(k)
(%,n)
Table 9.53: Degassing patterns for MADERAS-013
0.1820
0.1818
0.1820
0.1822
Normal
Isochron
0.000192
0.001355
0.001969
0.001543
0.000641
0.000453
0.000341
Age
± 0.0101 85.1
± 5.56%
Minimal External Error
Analytical Error







0.000109
0.000044
740 °C
BH6077

675 °C
BH6076

36Ar(a)
Degassing
Patterns
± 2σ
± 0.0067 85.2
± 3.69%
Minimal External Error
Analytical Error
40(r)/39(k)
Total Fusion
Age
Age Plateau
Results
Table 9.52: Continued
MSW
D
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(c)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.022684
0.000021
0.000192
0.001160
0.002221
0.002771
0.005183
0.005498
0.004165
0.001106
0.000366
38Ar(k)
0.04
1.13
0.36
0.10
0.14
0.12
0.08
0.07
0.07
0.17
0.22
%1σ
113

950 °C
1010 °C
1080 °C
1160 °C
1225 °C
BH6081
BH6082
BH6083
BH6084
BH6085
900 °C
BH6080








800 °C
850 °C
BH6078
BH6079
740 °C
BH6077
0.682166
0.176853
0.145321
0.186914
0.182855
0.177593
0.185876
0.180434
0.196985
0.214107

675 °C
BH6076
1σ
1.55217
0.22824
0.05198
0.01069
0.01033
0.00592
0.00619
0.00852
0.02930
0.28
11.55
40(r+a)
0.04
1.13
0.36
0.10
0.14
0.12
0.08
0.07
0.07
0.17
0.22
%1σ
1.881251
0.000290
0.000005
0.000017
0.000024
0.000035
0.000043
0.000058
0.000055
0.000039
0.000011
0.000004
39Ar(ca)
0.04
1.03
4.18
3.03
2.89
2.78
2.75
2.66
2.69
2.69
3.23
5.32
%1σ
0.342396
0.001211
0.002811
0.013979
0.034426
0.042019
0.076329
0.084735
0.062318
0.018062
0.006506
40Ar(r)
2.78
227.53
129.05
35.77
5.72
5.65
3.33
3.33
4.72
14.88
34.00
%1σ
2.046307
0.056780
0.400269
0.581694
0.455811
0.189366
0.133906
0.100628
0.082615
0.032128
0.013111
40Ar(a)
0.057992
0.403080
0.595673
0.490236
0.231385
0.210234
0.185363
0.144933
0.050190
0.00013
0.00034
0.00021
0.00033
0.00021
0.00016
0.00019
0.00013
0.00010
0.00007
1σ
32.560725
25.333551
6.190713
2.661229
1.006725
0.489082
0.406566
0.419590
0.547315
0.645521
40Ar/39Ar
0.37239
0.09340
0.00673
0.00402
0.00154
0.00054
0.00050
0.00048
0.00142
0.00274
1σ
4.504354
1.546158
0.368404
0.283255
0.275950
0.200863
0.177934
0.167348
0.172543
0.185184
37Ar/39Ar
0.19488
0.04725
0.01064
0.00789
0.00760
0.00535
0.00479
0.00451
0.00557
0.00987
1σ
0.109076
0.085541
0.020556
0.008448
0.002861
0.001107
0.000794
0.000854
0.001231
0.001509
36Ar/39Ar
%1σ
0.00537
0.00083
0.00018
0.00004
0.00003
0.00002
0.00002
0.00003
0.00010
0.00025
1σ
0.46
4.85
0.90
0.86
0.43
1.25
1.90
2.80
3.56
8.36
16.86
Table 9.54: Additional parameters for MADERAS-013
1.880961
0.001776
0.015894
0.096197
0.184179
0.229797
0.429796
0.455868
0.345378
0.091692
0.030385
39Ar(k)
0.019616
395.75
119.36
27.58
8.36
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
0.07280
0.024574
0.000595
40(r)/39(k)
0.00
0.000000
0.000004
0.000027
0.000176
0.000388
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
38Ar(cl)
Additional
Parameters
0.00
0.00
0.000000
0.000000
0.00
0.00
0.000000
0.000000
0.00
0.00
0.000000
0.000000
0.00
0.00
0.00
0.000000
0.000000
0.00
0.000000
0.000000
%1σ
38Ar(ca)
Table 9.53: Continued
133.295
133.260
133.226
133.190
133.156
133.121
133.085
133.051
133.016
132.981
Time
(days)
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(c)
13.91903120
13.90948834
13.89995202
13.89023171
13.88070859
13.87119200
13.86149180
13.85198839
13.84249149
0.56
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
1.00094112
1.00094087
1.00094063
1.00094038
1.00094013
1.00093989
1.00093964
1.00093939
1.00093915
1.00093890
39Ar
(decay)
2.388702
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
40Ar(k)
13.83281136
37Ar
(decay)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
%1σ
3.423E-16
2.379E-15
3.516E-15
2.893E-15
1.366E-15
1.241E-15
1.094E-15
8.554E-16
2.962E-16
1.158E-16
40Ar
(moles)
114
0.000077
0.000146
0.000331
0.000403
0.000524
0.000713
0.001633
0.002064
0.001439
0.000261
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
36Ar
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
Intercept
Values
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
Procedure
Blanks
0.000005
0.000007
0.000008
0.000008
0.000006
0.000006
0.000003
0.000016
0.000011
0.000007
1σ
0.000031
0.000031
0.000030
0.000033
0.000038
0.000042
0.000044
0.000046
0.000050
0.000063
36Ar
0.1077
0.3834
0.2945
0.6735
0.9127
0.9991
0.9703
0.9717
0.3512
r2
0.000001
0.000013
0.000025
0.000029
0.000029
0.000024
0.000016
0.000007
0.000008
0.000029
37Ar
0.000015
0.000015
0.000015
0.000015
0.000015
0.000015
0.000015
0.000015
0.000015
0.000015
1σ
0.000002
0.000014
0.000018
0.000015
0.000009
0.000005
0.000002
0.000003
0.000007
0.000005
38Ar
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
0.000012
1σ
AVE
EXP
EXP
EXP
EXP
LIN
PAR
LIN
PAR
EXP
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
5 of 8
6 of 8
7 of 8
8 of 8
0.000414
0.001173
0.004262
0.005972
0.006349
0.004664
0.003830
0.002596
0.001804
0.000615
37Ar
0.000012
0.000016
0.000020
0.000030
0.000021
0.000035
0.000031
0.000027
0.000023
0.000012
1σ
0.6578
0.8711
0.9845
0.9808
0.9865
0.9614
0.9565
0.9359
0.9007
0.5923
r2
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
39Ar
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
0.000005
0.000005
0.000006
0.000008
0.000011
0.000010
0.000007
0.000002
0.000007
0.000033
Table 9.56: Intercept values for MADERAS-013
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
0.000006
1σ
Table 9.55: Procedure blanks for MADERAS-013
0.000377
0.001115
0.003930
0.005403
0.005299
0.002884
0.002930
0.001724
0.000483
0.000067
38Ar
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
0.000010
1σ
0.000019
0.000013
0.000024
0.000054
0.000060
0.000035
0.000030
0.000047
0.000029
0.000013
1σ
0.008439
0.008439
0.008887
0.009459
0.009983
0.010370
0.010717
0.011364
0.013592
0.017967
40Ar
0.5255
0.9221
0.9772
0.9229
0.9004
0.9204
0.9155
0.6132
0.0719
0.0930
r2
EXP
EXP
EXP
EXP
EXP
PAR
EXP
EXP
EXP
EXP
0.000053
0.000053
0.000053
0.000053
0.000053
0.000053
0.000053
0.000053
0.000053
0.000053
1σ
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
8 of 8
Table 9.56: Continued
39Ar
1σ
r2
0.030521
0.092092
0.346872
0.457845
0.431669
0.230814
0.184994
0.096627
0.015985
0.001821
0.000066
0.000150
0.000216
0.000295
0.000311
0.000279
0.000245
0.000095
0.000056
0.000017
0.9943
0.9980
0.9997
0.9997
0.9996
0.9989
0.9984
0.9990
0.0843
0.9870
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
8 of 8
8 of 8
8 of 8
8 of 8
7 of 8
7 of 8
8 of 8
8 of 8
8 of 8
8 of 8
40Ar
1σ
r2
0.028056
0.058629
0.153820
0.194822
0.220217
0.241755
0.500953
0.607038
0.416671
0.075959
0.000048
0.000085
0.000123
0.000181
0.000155
0.000199
0.000322
0.000201
0.000340
0.000117
0.7891
0.9913
0.9975
0.9969
0.9986
0.9990
0.9995
0.9999
0.9994
0.9948
LIN
PAR
EXP
EXP
EXP
EXP
EXP
EXP
EXP
EXP
7 of 8
8 of 8
7 of 8
8 of 8
8 of 8
7 of 8
8 of 8
8 of 8
8 of 8
7 of 8
Temp
Table 9.57: Sample parameters for MADERAS-013
Standard
(in Ma)
BH6076
675 °C
MAD013
groundmass
UW93D48
Brian Jicha
675
28.201
0.08
0.0002554
0.08
1.00515
BH6077
740 °C
MAD013
groundmass
UW93D48
Brian Jicha
740
28.201
0.08
0.0002554
0.08
1.00515
Sample
Parameters
Sample
Material
Location
Analyst
%1σ
J
%1σ
MDF
BH6078
800 °C
MAD013
groundmass
UW93D48
Brian Jicha
800
28.201
0.08
0.0002554
0.08
1.00515
BH6079
850 °C
MAD013
groundmass
UW93D48
Brian Jicha
850
28.201
0.08
0.0002554
0.08
1.00515
BH6080
900 °C
MAD013
groundmass
UW93D48
Brian Jicha
900
28.201
0.08
0.0002554
0.08
1.00515
BH6081
950 °C
MAD013
groundmass
UW93D48
Brian Jicha
950
28.201
0.08
0.0002554
0.08
1.00515
BH6082
1010 °C
MAD013
groundmass
UW93D48
Brian Jicha
1010
28.201
0.08
0.0002554
0.08
1.00515
BH6083
1080 °C
MAD013
groundmass
UW93D48
Brian Jicha
1080
28.201
0.08
0.0002554
0.08
1.00515
BH6084
1160 °C
MAD013
groundmass
UW93D48
Brian Jicha
1160
28.201
0.08
0.0002554
0.08
1.00515
BH6085
1225 °C
MAD013
groundmass
UW93D48
Brian Jicha
1225
28.201
0.08
0.0002554
0.08
1.00515
Sensitivity
(mol/volt)
Month
Year
Hour
0.03
1
5.902E-15
25
OCT
2011
16
0.03
1
5.902E-15
25
OCT
2011
17
34
0.03
1
5.902E-15
25
OCT
2011
18
0.03
1
5.902E-15
25
OCT
2011
0.03
1
5.902E-15
25
OCT
0.03
1
5.902E-15
25
0.03
1
5.902E-15
0.03
1
0.03
0.03
Irradiation
Project
43
001
UW93
001
UW93
24
001
19
14
2011
20
OCT
2011
25
OCT
5.902E-15
25
1
5.902E-15
1
5.902E-15
Experiment
Nmb
Resist
Volume
Ratio
Min
%1σ
Day
Table 9.57: Continued
Standard
Name
UW93D
UW93D48
01
FCS
UW93D
UW93D48
01
FCS
UW93
UW93D
UW93D48
01
FCS
001
UW93
UW93D
UW93D48
01
FCS
05
001
UW93
UW93D
UW93D48
01
FCS
20
55
001
UW93
UW93D
UW93D48
01
FCS
2011
21
45
001
UW93
UW93D
UW93D48
01
FCS
OCT
2011
22
36
001
UW93
UW93D
UW93D48
01
FCS
25
OCT
2011
23
26
001
UW93
UW93D
UW93D48
01
FCS
26
OCT
2011
00
16
001
UW93
UW93D
UW93D48
01
FCS
115
116
BH6076
BH6077
BH6078
BH6079
BH6080
BH6081
BH6082
BH6083
BH6084
BH6085
675 °C
740 °C
800 °C
850 °C
900 °C
950 °C
1010 °C
1080 °C
1160 °C
1225 °C
Irradiation
Constants
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
295.5
40/36(a)
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0.01206
0
0
0
0
0
0
0
0
0
0
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
1.493
38/36(c)
3
3
3
3
3
3
3
3
3
3
%1σ
0
0
0
0
0
0
0
0
0
0
%1σ
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
0.43
K/Ca
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
K/Cl
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
38/37(ca)
Ca/Cl
%1σ
%1σ
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
0.000673
39/37(ca)
Table 9.58: Continued
0
0
0
0
0
0
0
0
0
0
%1σ
36/38(cl)
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
38/36(a)
%1σ
35
35
35
35
35
35
35
35
35
35
%1σ
38/39(k)
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
0.018
40/36(c)
Table 9.58: Irradiation constants for MADERAS-013
0
0
0
0
0
0
0
0
0
0
%1σ
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
0.000264
36/37(ca)
0
0
0
0
0
0
0
0
0
0
%1σ
0
0
0
0
0
0
0
0
0
0
40/39(k)
0
0
0
0
0
0
0
0
0
0
%1σ
UW93D48.AGE >>> MAD013 >>> UW93D PROJECT
500
Ar-Ages in Ka
450
WEIGHTED PLATEAU
85.2 ± 3.1
TOTAL FUSION
85.1 ± 4.7
NORMAL ISOCHRON
85.0 ± 3.8
INVERSE ISOCHRON
85.1 ± 1.9
400
350
300
MSWD
0.25
250
200
85.2 ± 3.1 Ka
150
100
Sample Info
50
groundmass
UW93D48
Brian Jicha
0
IRR = UW93
J = 0.00025540 ± 0.00000020
50
100
0
10
20
30
40
50
60
70
80
90
100
Cumulative 39Ar Released [ % ]
Figure 9.17: Age plateau for MADERAS-013
UW93D48.AGE >>> MAD013 >>> UW93D PROJECT
3.9
Ar-Ages in Ka
3.6
WEIGHTED PLATEAU
85.2 ± 3.1
TOTAL FUSION
85.1 ± 4.7
NORMAL ISOCHRON
85.0 ± 3.8
INVERSE ISOCHRON
85.1 ± 1.9
3.3
3.0
2.7
2.4
2.1
1.8
1.5
1.2
Sample Info
0.19 ± 0.22
groundmass
UW93D48
Brian Jicha
0.9
0.6
IRR = UW93
J = 0.00025540 ± 0.00000020
0.3
0.0
0
10
20
30
40
50
60
Cumulative 39Ar Released [ % ]
Figure 9.18: K-Ca plateau for MADERAS-013
117
70
80
90
100
UW93D48.AGE >>> MAD013 >>> UW93D PROJECT
700
Ar-Ages in Ka
650
WEIGHTED PLATEAU
85.2 ± 3.1
TOTAL FUSION
85.1 ± 4.7
NORMAL ISOCHRON
85.0 ± 3.8
INVERSE ISOCHRON
85.1 ± 1.9
600
550
500
450
MSWD
0.28
400
40AR/36AR INTERCEPT
295.6 ± 2.4
350
300
250
Sample Info
200
groundmass
UW93D48
Brian Jicha
150
100
IRR = UW93
J = 0.00025540 ± 0.00000020
50
0
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
39Ar / 36Ar
Figure 9.19: Normal isochron for MADERAS-013
UW93D48.AGE >>> MAD013 >>> UW93D PROJECT
0.0045
Ar-Ages in Ka
WEIGHTED PLATEAU
85.2 ± 3.1
TOTAL FUSION
85.1 ± 4.7
NORMAL ISOCHRON
85.0 ± 3.8
INVERSE ISOCHRON
85.1 ± 1.9
0.0040
0.0035
0.0030
MSWD
0.28
0.0025
40AR/36AR INTERCEPT
295.6 ± 1.2
0.0020
0.0015
Sample Info
0.0010
groundmass
UW93D48
Brian Jicha
0.0005
IRR = UW93
J = 0.00025540 ± 0.00000020
0.0000
0
1
1
2
2
3
3
4
4
39Ar / 40Ar
Figure 9.20: Inverse isochron for MADERAS-013
118
5
5
6
6
7
7