NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES
105°45'0"W
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NMBGMR Open-file Geologic Map 168
169
Last Modified May, 2008
A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
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DESCRIPTION OF MAP UNITS
105°37'30"W
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444000
36°45'0"N
4067000
Qfu
4067000
Qfyv
Tb
Tvc
Tvc
Tag
Qc
Tvc
Qc
Tvb
Qal
Tvc
Tvc
Qe
Tb
Qfyv
4066000
4066000
Qao3
Qfyv
Qls
Qfyv
Qfyv
Qao3
Qfy
Qty
Qal
Tag Tag
Qfyv
Tb
4065000
Qal
Tag
4065000
Qfyv
Qt7rr
Tb
Tb
Qal
Tb
Tat
Qfv
Qfu
4064000
Tag
Qc Qc
Tag
Tag
Qal
Qc Qao3 Qao3
Tb
Tag
Tb
Qao3
Qal
Tag Qc
QcQc
Tb
Qc
Qc
Qc Tag
Tb
Qfyv
Qe
Tat
Tb
Qfyv
4063000
Qfy
Qfu
A'
Qfu
Qfu
QTg
4063000
Qfu
Tvb
Qls
Qfyv
Qfyv
Qal
QTg
Qfyv
QTg
Qfy
4062000
Qc Qal
Qfu
Tb
Tvp
Qt2rr
36°42'30"N
Qc
Qfyv
Qt3rr
Qao3
Tag
Qfu
Tb
4062000
QTg
Qls
Tvb
Qfu
Qao2
QTg
Tvp
Qfu
QTg
Qfu
Qe
Tb
QTg
Tb
Qt2rr
Qfyv
Qal
4061000
Qc
Tb
Qfy
Qfu
Qfu
Qao3
Tvr
Qfyv
Qao3
Tvr
Qfu
Qfy
Tvr
QTg
Tvr
Tvr
Tvr
Qal
Qt0rr
Qt5
QTg
QTg
Qal
Tvr
Qal
Tag
Tag
4059000
Qc
A
4059000
Tvr
Qfyv
Qt1rr
Tb
Qc
Tvr
Qc
Qc
Tdmc
36°40'0"N
Landslide deposits (late Pleistocene to Holocene) — Poorly sorted sand to boulders, includes large rotational slide blocks within the
Rio Grande gorge, which include large, rotated and detached beds of Servilleta basalt (Tb); may also include areas underlain by Holocene
colluvium in Rio Grande and Red River gorges.
Tvr
Qf1
Qfy
Qc
Qfu
Tb
Tb
Young alluvial-fan deposits from volcanic terrane (latest Pleistocene to Holocene) — Poorly sorted silt, sand, pebbles, cobbles, and
boulders; clasts primarily of volcanic rock types; associated soils have stage I calcium carbonate development; source areas primarily
volcanic terrane on west side of Rio Grande and drainages on Guadalupe Mountain.
Tag
Dacite of Guadalupe Mountain (Pliocene) —
SiO2, 6.3 wt% Na20+K20) and associated
near-vent pyroclastic deposits. Contains sparse, small phenocrysts of plagioclase, hypersthene and augite in a pilotaxitic glassy groundmass.
Qfy
Qf1
QTg
Qc
4057000
QTg
Qf1
Qf1
Tdm
Qf1
Qal
Tdmc
Qt0rg
4056000
Stream terrace deposits (late Pleistocene) — Poorly sorted silt, sand, pebbles, cobbles, and boulders; clasts primarily of quartzite, schist,
granite, and volcanic rock types; associated soils have stage II to III calcium carbonate development; typically present as thin (< 5 m)
alluvial deposit on strath surface cut on volcanic bedrock or unit QTg (Lama Formation); equivalent to Qt5 and Qt4 of Pazzaglia (1989)
and Kelson (1986). (Qt5rr and Qt4rr from Red River watershed).
Qf1
4056000
Tdm
Tvt
Tb
Tvt
4055000
Qfy
Tdmc
Tdmc
Qf1
Qe
4054000
4054000
QTg
Tvt
Qfy
Qfyv
Tg
Tb
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1
CERRO
NEW MEXICO
TRES
PIEDRAS NE
CERRO DE
LOS TAOSES
GUADALUPE
Guadalupe
MOUNTAIN
Mountain
ARROYO
HONDO
0.5
1000
0
1000
0
2000
3000
5000
6000
443000
7000 FEET
ARROYO
SECO
Magnetic Declination
July, 2004
9º 32' East
At Map Center
0.5
0
105°37'30"W
May 2008
QUESTA
1
444000
Geologic map of the
Guadalupe Mountain quadrangle,
Taos County, New Mexico.
1 MILE
4000
Qfy
36°37'30"N
442000
1:24,000
SUNSHINE
QTg
Qfy
Base map from U.S. Geological Survey 1963, from photographs taken 1962, field checked in 1963.
1927 North American datum, UTM projection -- zone 13N
1000-meter Universal Transverse Mercator grid, zone 13, shown in red
CERRO DE
LA OLLA
QTg
Qal
36°37'30"N
1 KILOMETER
by
Keith I. Kelson , Ren Thompson2, and Paul W. Bauer3.
1
CONTOUR INTERVAL 20 FEET
NATIONAL GEODETIC VERTICAL DATUM OF 1929
William Lettis and Associates, Inc., 1777 Botelho Dr., Suite 262, Walnut Creek, CA, 94596
U.S. Geological Survey, Box 25046, MS 980, Denver Federal Center, Denver, CO 80225
3
New Mexico Bureau of Geology and Mineral Resources, 801 Leroy Pl., Socorro, NM,87801
1
QUADRANGLE LOCATION
This draft geologic map is preliminary and will undergo revision. It was produced
from either scans of hand-drafted originals or from digitally drafted original maps
and figures using a wide variety of software, and is currently in cartographic production.
It is being distributed in this draft form as part of the bureau's Open-file map series
(OFGM), due to high demand for current geologic map data in these areas where
STATEMAP quadrangles are located, and it is the bureau's policy to disseminate
geologic data to the public as soon as possible.
After this map has undergone scientific peer review, editing, and final cartographic
production adhering to bureau map standards, it will be released in our Geologic Map
(GM) series. This final version will receive a new GM number and will supercede
this preliminary open-file geologic map.
DRAFT
New Mexico Bureau of Geology and Mineral Resources
Open-file Map Series
2
168
OF-GM 169
COMMENTS TO MAP USERS
Mapping of this quadrangle was funded by a matching-funds grant from the STATEMAP program
of the National Cooperative Geologic Mapping Act, administered by the U. S. Geological Survey,
and by the New Mexico Bureau of Geology and Mineral Resources, (Dr. Peter A. Scholle,
Director and State Geologist, Dr. J. Michael Timmons, Geologic Mapping Program Manager).
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, New Mexico
87801-4796
[505] 835-5490
http://geoinfo.nmt.edu
This and other STATEMAP quadrangles are (or soon will be) available
for free download in both PDF and ArcGIS formats at:
http://geoinfo.nmt.edu/publications/maps/geologic/ofgm/home.html
Tvc
Eroded remnants of large lava dome of porphyritic trachyandesite (63 wt% SiO2, 7.7 wt%
Na2O+K2O
Xenoliths of Precambrian schist, gneiss, and granite are common. Flow breccias preserved around margins of dome and ramp structures
common throughout the exposed interior. Appelt (1998) reports 40Ar/39Ar ages of 5.31 ± 0.31 and 5.32 ± 0.08 Ma for groundmass separates
from the west and east sides of the dome, respectively.
Tam
augite, Fe-Ti oxides. The lower slopes of Cerro Montoso in the western side of the map area are often mantled in colluvium and rarely
Older alluvium (middle? Pleistocene) — Poorly sorted silt, sand, and pebbles; clasts primarily of granitic, metamorphic, basaltic, and
intermediate volcanic rocks; distinctly smaller clast sizes than units Qt2rr, Qt1rr, and Qt0rr; upper soil horizons locally affected by surface
erosion; may be mantled locally by unit Qe; typically present as thin (< 5 m) alluvial deposit on strath surface cut on volcanic bedrock near
rim of Rio Grande gorge; located only upstream of the Red River fault zone; correlative with unit Qao3 in Sunshine quadrangle (Ruleman
et al., 2007); subunit Qao3rg interpreted as axial Rio Grande deposits; subunit Qao3f interpreted as tributary-fan deposits derived from
east of Rio Grande.
Amalia Tuff (Oligocene) —
40
Cerro Montoso.
Tat
Tvb
Older alluvium (middle? Pleistocene) — Poorly sorted silt, sand, and pebbles; clasts primarily of granitic, metamorphic, basaltic, and
intermediate volcanic rocks; upper soil horizons locally affected by surface erosion; may be mantled locally by unit Qe; located only
et al. (2007); subunit Qao2rg interpreted as axial
Rio Grande deposits; subunit Qao2f interpreted as tributary-fan deposits derived from east of Rio Grande.
Fe-Ti oxides, sphene, and alkali amphibole phenocrysts are minor. Forms
40Ar/39Ar sanidine age of
approximately 25.1 Ma. Erupted from the Questa caldera approximately 15 km to the east (Lipman and Reed, 1989).
Dacite of Unamed Cerito East of Montoso (Pliocene) — Dark gray, sparsely phyric, low-silica, calc-alkaline dacite (64 wt% SiO2, 6
wt% Na20+K20
subhedral olivine and quartz xenocrysts in a microcrystalline to glassy groundmass. Locally includes small volume, aerially restricted
Tao
Dacite of Unamed Cerito East of Montoso near vent deposits (Pliocene) —
Tdm. Predominantly cinder, spatter agglutinate and volcanic bombs locally.
Andesite of Cerro de la Olla (Pliocene) — Dark gray to black, porphyritic olivine andesite (58.5 wt% SiO2, 6.9 wt% Na20+K20
erupted from vents near summit of Cerro de la Olla, one of the largest, petrologically uniform, shield volcanoes of the Taos Plateau volcanic
A geologic map displays information on the distribution, nature, orientation, and age relationships
of rock and deposits and the occurrence of structural features. Geologic and fault contacts are
irregular surfaces that form boundaries between different types or ages of units. Data depicted
on this geologic quadrangle map may be based on any of the following: reconnaissance field
geologic mapping, compilation of published and unpublished work, and photogeologic interpretation.
Locations of contacts are not surveyed, but are plotted by interpretation of the position of a given
contact onto a topographic base map; therefore, the accuracy of contact locations depends on the
scale of mapping and the interpretation of the geologist(s). Any enlargement of this map could cause
misunderstanding in the detail of mapping and may result in erroneous interpretations. Site-specific
conditions should be verified by detailed surface mapping or subsurface exploration. Topographic
and cultural changes associated with recent development may not be shown.
Cross sections are constructed based upon the interpretations of the author made from geologic
mapping, and available geophysical, and subsurface (drillhole) data. Cross-sections should be used as
an aid to understanding the general geologic framework of the map area, and not be the sole source
of information for use in locating or designing wells, buildings, roads, or other man-made structures.
The map has not been reviewed according to New Mexico Bureau of Geology and Mineral Resources
standards. The contents of the report and map should not be considered final and complete until
reviewed and published by the New Mexico Bureau of Geology and Mineral Resources. The views and
conclusions contained in this document are those of the authors and should not be interpreted as
necessarily representing the official policies, either expressed or implied, of the State of New Mexico, or
the U.S. Government.
Red River
Piedmonts
Qal, Qc, Qe
Qfyv, Qfy
Qt7rr
Latest Pleistocene
Qls
Qfv
Late Pleistocene
of Brushy Mountain. Lower rhyolite contains phenocrysts of plagioclase and altered biotite, light brown altered pumice and angular to
subangular vitrophyric inclusions (<0.5 cm to several cm) containing plagioclase phenocrysts and reddish-brown dacite inclusions (2
Tat). Post Amalia Tuff deposits include light-grey to white
of hornblende, plagioclase, clinopyroxene, Fe-Ti
Servilleta Formation, interbasalt gravel (Pliocene) —
as 70 m thick in southern part of quadrangle, as exposed in the Rio Grande gorge. Typically rounded to subrounded pebble- to cobble-size
Rio Grande
South of RRFZ
Qty
Volcanic deposits of Brushy Mountain (Oligocene) —
Poorly sorted silt, sand, pebbles, and boulders; clasts of basalt,
quartzite, metamorphic rock types, volcanic rock types; soil development not documented but upper soil horizons probably affected by
surface erosion; present only locally along rim of Red River gorge, inset into Qt0rr gravel deposits and Tertiary volcanic rocks along Red
River gorge.
Servilleta Formation, basalt (Pliocene) — Flows of dark-gray tholeiitic basalt characterized by small olivine phenocrysts, diktytaxitic
Rio Grande
North of RRFZ
Holocene
0.08 (Lipman and Mehnert, 1979). Exposed in quarry on south side of Brushy Mountain and north side of Cerro Montoso. Thin (< 2-3
Old alluvium (late Tertiary to middle Pleistocene) — Poorly sorted sand, pebbles, and cobbles; clasts of basalt, quartzite, metamorphic
rock types, and volcanic rock types; locally high percentage of angular to subangular quartzite pebbles and cobbles; present along piedmont
between Sangre de Cristo range front and Red River and Rio Grande gorges; underlies Garrapata Ridge and probably much of Cebolla Mesa
Sedimentary Deposits
Ar/39Ar ages of 5.88 ± 0.18 Ma for a groundmass separate from the west side of
Alluvial fan deposits (middle Pleistocene) — Poorly sorted silt, sand, and rare pebbles; clasts primarily of granitic, intermediate volcanic,
basaltic, and metamorphic rock types; stage III and IV calcium carbonate development where preserved, although soil horizons are
commonly affected by surface erosion; correlative with unit Q1p of Kelson (1986); differentiated from unit QTg by larger clast size, less
oxidation, poor sorting, absence of abundant manganese oxide staining, and clasts that are less weathered.
Poorly sorted sand, pebbles, and cobbles; clasts of
basalt, quartzite, and many volcanic and metamorphic rock types; upper part commonly affected by surface erosion; present upstream and
Qt0rr); merges with unit Qt0rg in
southernmost part of quadrangle and in Arroyo Hondo quadrangle.
Guadalupe Mountain Quadrangle, Taos County, New Mexico
Andesite of Cerro Montoso (Pliocene) — Dark gray to black, porphyritic olivine andesite (57.6 wt% SiO2, 8 wt% Na20+K20) lava
Stream terrace deposits (middle? Pleistocene) — Poorly sorted silt, sand, pebbles, cobbles, and boulders; clasts primarily of quartzite,
schist, granite, and volcanic rock types; associated soils have stage III calcium carbonate development; typically present as thin (< 5 m)
alluvial deposit on strath surface cut on volcanic bedrock or unit QTg (Lama Formation); equivalent to Qt3 and Qt2 of Pazzaglia (1989)
and Kelson (1986). (Qt3rr and Qt2rr from Red River watershed).
augite, Fe-Ti oxides. The lower slopes of Cerro de la Olla in the northwestern part of the map area are often mantled in colluvium and rarely
Tvt
reports 40Ar/39Ar ages of 5.11 ± 0.08 and 5.34 ± 0.06 Ma for groundmass separates from the south side of Guadalupe Mountain.
Undifferentiated alluvial fan deposits (middle to late Pleistocene) — Probably correlative with alluvial units Qt2 through Qt6; poorly
Tb) and local interbedded sedimentary deposits (Leninger, 1982, Peterson, 1981); neither
relations shown at the scale of this map due to extensive distribution of landslide deposits (Qls) in the southern part of the Rio Grande gorge
Qt7
Qal
west suggesting a primary source area at Guadalupe Mountain. Near-vent pyroclastic deposits consisting mostly of spatter and agglutinate
are most abundant near the steep-sided geographic north and south peaks of Guadalupe Mountain. Spatter and cinder deposits are found
Undifferentiated alluvial fan deposits (middle to late Pleistocene) — Probably correlative with alluvial units Qt2 through Qt6; poorly
Qal
Qls
4055000
brecciated carapaces where exposed in cross-section. Flows exposed in Rio Grande gorge vary considerably in thickness from a few meters
Stream terrace deposits (early to middle Holocene) — Poorly sorted silt, sand, pebbles, cobbles, and boulders; clasts primarily of
quartzite, schist, granite, and volcanic rock types; associated soils have stage I calcium carbonate development; typically present as thin (<
5 m) alluvial deposit on strath surface cut on volcanic bedrock deposit; equivalent to Qt7 of Pazzaglia (1989) and Kelson (1986). (Qt7rr
from Red River watershed).
Qt5rr
Qfu
Qt4rr
Middle Pleistocene
Qt3rr
Qao3
containing olivine, clinopyroxene, and plagioclase phenocrysts, plagioclase glomerocrysts, and minor orthopyroxene microphenocrysts
Fe-Ti oxides. The upper
Tvt
Qt2rr
Qao2
Early Pleistocene
Qt1rr
Qf1
1.2 Ma
1.6 Ma
Qt0rg
Qt0rr
QTg
(Lama Fm.)
Volcanic deposits of Timber Mountain (Oligocene) —
Igneous Rocks and Coeval Sedimentary Deposits
plagioclase, sanidine, quartz, and biotite with subordinate amounts of Fe-Ti oxides, clinopyroxene and orthopyroxene in a glassy to partially
Pliocene
Tdmc
containing variable amounts of plagioclase, clinopyroxene, Fe-Ti oxides hornblende plus or minus biotite and sanidine xenocryts. Locally
contains abundant micropillows of basaltic lava and dacite xenoliths as much as 10 cm in diameter. Lower dacite sequence is separated
Tg
groundmass composed of plagioclase, clinopyroxene, and Fe-Ti oxides. Upper dacite sequence contains medium- to light-gray porphyritic,
Fe-Ti oxides in
variable proportion.
ooo
Tb
Tb
ooo
Tg
ooo
~4.8 Ma
REFERENCES
Tao
4.97 Ma
Tvc
5.31 Ma
Appelt, R. M., 1998, Ar/
Colorado: MS thesis, New Mexico Institute of Mining and Technology, Socorro, NM, 58 p.
40
Tdm
~3 Ma
ooo
Tvr
Tvp
Tag
39
Tam
Dungan, M. A., Muehlberger, W. R., Leininger, L., Peterson, C., McMillan, N. J., Gunn, G., Lindstrum, M., and Haskin, L., 1984, Volcanic
and sedimentary stratigraphy of the Rio Grande gorge and the late Cenozoic geologic evolution of the San Luis Valley: New Mexico
Geological Society, 35th Field Conference, Guidebook, p. 157-170.
Kelson, K. I., 1986, Long-term tributary adjustments to base-level lowering in northern Rio Grande rift, New Mexico: M.S. thesis.
University of New Mexico, Albuquerque, NM, 210 p.
Lambert, P. W., 1966, Notes on the late Cenozoic geology of the Taos-Questa area, New Mexico: New Mexico Geological Society, 17th
Field Conference, Guidebook, p. 43-50.
silica diagram: Journal of Petrology, v. 27, p. 745-750
Leininger, R. L., 1982, Cenozoic evolution of the southernmost Taos Plateau, New Mexico: M.S. thesis, University of Texas, Austin, TX,
110 p.
Qls
4057000
Tg
QTg
Qfy
Qf1
Thompson, R. A., Dungan, M. A., and Lipman, P. W., 1986, Multiple differentiation processes in early-rift calc-alkaline volcanics, northern
Rio Grande rift, New Mexico: Journal of Geophysical Research, v. 91, p. 6046-6058.
Thompson, R. A., and Machette, M. N., 1989, Geologic map of the San Luis Hills area, Conejos and Costilla counties, Colorado: U.S.
Geological Survey Miscellaneous Investigations Series Map I-1906, scale 1:50,000.
Undivided pyroclastic deposits (Pliocene) — Pyroclastic deposits of near vent origin exposed in Rio Grande gorge. Predominantly
fragmental deposits including cinder, ash and volcanic lithic fragments.
the youngest eruptive activity in the map area.
36°40'0"N
Qf1
Qe
4058000
Qal
Tb
Ruleman, C., Shroba, R., and Thompson, R., 2007, Chapter C – Field trip day 3; Quaternary Geology of Sunshine Valley and Associated
Neotectonics along the Latir Peaks Section of the Sangre de Cristo fault zone: in: Machette, M. N., et al. (eds.), Quaternary Geology
of the San Luis Basin of Colorado and New Mexico, 2007 Friends of the Pleistocene Field Trip, Rocky Mountain Section, 24 p.
Thompson, R. A., and Schilling, S. P., 1988, Generalized geologic maps of the Brushy Mountain and Timber Mountain areas, Taos County,
New Mexico:
, 1 plate.
Tvp
Qfu
Tb
Peterson, C. M., 1981, Late Cenozoic stratigraphy and structure of the Taos Plateau, northern New Mexico: M.S. thesis, University of
Texas, Austin, TX, 57 p.
andesite of the Servilleta Fm near the base of the Red River gorge, not differentiated at the map scale.
Young alluvial-fan and stream terrace deposits (latest Pleistocene to Holocene) — Poorly sorted silt, sand, pebbles, cobbles, and boulders;
clasts primarily of quartzite, schist, granite, and volcanic rock types; associated soils have stage I calcium carbonate development.
form columnar-jointed cliffs where exposed with a maximum thickness of approximately 200 m in the Rio Grande gorge south of the map
et al., 1984). These
packages are separated by sedimentary intervals that are as much as 70 m thick in southern part of quadrangle (Leininger, 1982). Tabular
plagioclase and sparse olivine are the only phenocrysts. 40Ar/39Ar ages from basalts exposed in the Rio Grande gorge range in age from 4.81
Qc
Tb
4058000
Tb
Tag
Tb
Qt0rg
Tam
to 10 meters in thickness, and are laterally continuous based on exposures in the Red River canyon. In contrast, dacite lavas are typically
thick, up to tens of meters locally, and are characteristically discontinuous and aerially restricted. Locally, deposits of the Red River
Tertiary Volcanic Rocks and Sedimentary Deposits
QTg
Tag
Tag
Qt1rr
Pazzaglia, F. J., and Wells, S. G., 1990, Quaternary stratigraphy and geomorphology of the northern Rio Grande Rift: New Mexico Geological
Society Guidebook, 41st Field Conference, p. 423–430.
QTg
Qal
Qt0rr
Volcanic deposits of Red River volcano (Pliocene) — Includes a sequence of volcanic rocks and near vent pyroclastic deposits of moderate
relief on the south side of Guadalupe Mountain and in canyon exposures in the middle and upper reaches of the Red River in the map area.
common near hill 7,590’ on the south side of the Red River and capping dacite lavas exposed on both side of the Red River appear to have
been fed locally by dikes exposed on both side of the canyon. McMillan and Dungan (1986) report chemical compositions for the basaltic
andesite to dacite suite ranging from 52-61 wt% SiO2 and 4.2-7.4 wt% Na2O+K2O
typically contain 5-10% phenocrysts of olivine and plagiocalse; olivine phenocrysts can be large (up to 6 mm) exhibiting well-developed
skeletal overgrowths (McMillan and Dungan, 1986). Medium grey dacite lavas are porphyritic, containing 5-15% phenocryts of augite and
Eolian deposits (Pleistocene to Holocene) —
roadcuts; predominantly on eastern side of the Rio Grande; weak to moderate soil development.
Questa quadrangle underlies mesa between villages of Questa and Cerro; correlative with Lama Formation of Lambert (1966); probably
correlative with Blueberry Hill deposit in Arroyo Hondo and Taos quadrangles; contains ash layer in uppermost strata dated as 1.6 Ma
(elevation ca. 7,660 ft, M. Machette, USGS, personal comm., 2008); contains undated ash layer in roadcut near Red River Fish Hatchery
(elevation ca. 7,160 ft); contains undated ash layer in roadcut near Cerro Negro (UTM 439989, 4044603) on Arroyo Hondo quadrangle.
Tvr
Tvr
Qal
4060000
Tvr
Tvr
Qal
Qt0rr
Qt1rr
QTg
QTg
Qt3rr
Qt3rr QTg
Qt7
Qt7
Tb
Tvr
Tvr
Qfy
Qt5
Qt0rr
Qal
Qfu
Qe
Qt1rr
Tvr
Tvr
Qt0rr
Tb
4061000
Qt3rr
Tvr
Tvr
4060000
Tvr
Colluvial mantle on slopes, undifferentiated (middle Pleistocene to Holocene) — Poorly-sorted sand, pebbles and boulders; mantles
slopes in Red River gorge and northeastern side of Red River fault zone in eastern part of quadrangle; consists of thin mantle overlying
volcanic bedrock.
position, and distinct lithologic characteristics. In Guadalupe Mountain quadrangle, composed primarily of intermediate and basaltic
volcanic clasts.
Qfyv
36°42'30"N
Qt5rr
Qt4rr
Tb
Tat
Tvb
Poorly to moderately sorted sand, pebbles, and
boulders; clasts of granitic, metamorphic, volcanic, and sandstone rock types; clasts along Red River, Rio Grande, and tributaries draining
the Sangre de Cristo range are dominated by granitic rock types, quartzite and basalt; clasts along tributaries draining the western side of
the Rio Grande dominated by volcanic rock types; weak or no soil development.
predominantly volcanic clasts derived from local Tertiary volcanic terrane.
Tb
4064000
Pazzaglia, F. J., 1989,
front fault, Sangre de Cristo Mountains, north-central New Mexico: M.S. thesis, University of New Mexico, Albuquerque, NM,
246 p.
Cerro Montoso.
36°45'0"N
Tao
Ar/39Ar ages of 4.97 ± 0.06 Ma for a groundmass separate from the west side of
40
Rio Grande rift – Tectonics and magmatism, American Geophysical Union, Washington, D.C., p. 289-311.
in: Riecker, R.E. (ed.),
Journal of Geophysical Research, v. 91, p. 6329-6345.
Geological Survey Miscellaneous Investigations Series Map I-1907, Scale 1:48000.
U.S.
northern New Mexico: Journal of Geophysical Research, B, Solid Earth and Planets, v. 91, no. 6, p. 6029-6045.
Miggins, D. P., Thompson, R. A., Pillmore, C. L., Snee, L. W., and Stern, C. R., 2002, Extension and uplift of the northern Rio Grande rift:
evidence from 40Ar/39Ar geochronology from the Sangre de Cristo mountains, south-central Colorado and northern New Mexico:
Geological Society of America Special Paper 362, p. 47-64.
Oligocene
~23 Ma
Tvb
~25 Ma
Tat
5.88 Ma
Tvt
~ 26-24 Ma
5.11 Ma
5.34 Ma