NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES
NMBGMR Open-file Geologic Map 239
A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
Last Modified April 2013
QTsf
20
8
Qay1
Qay2
QTsf
Qay1b
Qay
Qay2
Qay1
Qay1a
Tsfl?
Qay2
af
Qay1
Qaro
Qay2
QTsf
QTsf
Qay1a
Qay1a
QTsf
Qay2
Qah
Qay
?
?
Qay1
?
QTsf
Qay2
Qah
Qay2
Qay
Qasu
Qay2
Qay2
Qay2
?
Qay1
Qay2
3746000
Qay
?
Qay1b
Qaro
Qah
Qary1
Qah
?
Qay2
Qay1b
3745000
Qay2
?
Thm
Qay1a
Qah
Qsa
?
?
?
Qafu
Qary1
?
Qay1a?
Qay1a
?
?
?
?
Qao?
Tlj
Qay1
?
Qasu
?
Qsa
Qay2
Qah
Qay
Qafu
?
?
?
?
Qao
?
?
Qay1a
Qay1
Qay2
?
?
QTsf
Qah
?
?
?
Qay1as
Qay2
Qpy2
Qsa
QTsf Qay1
Qay1
Qao2
QTsf
Qsa
3740 000
Qay2
Qasu
?
Qay2
Qay2
QTsf
Qah
Qay
Qasu
29
Tlj
2
27
74
Tlj
Qay2
30
Qao1
39 31
41
Qasu
Qay
Qao1
QTsf
1
af
Qao 2
Qao
Qay1
Qao 2
Qao 2
Tlj
?
Qay
?
Qsa
?
QTsf
Qpo
Qasu
Qasu
Qpo
Qpy2
Qay
Qay
Qay
?
? ?
Qay2
?
Qpo
Qay
?
?
41
Tvp?
Qay
Qay2
Qay1
Qasu
QTsf
Qah
QTsf
?
Qsa
Qafo
Qay
Qao1
305000
304000
107°07'30"W
?
?
Qafo
306000
Qay1
QTsf
Qafo?
Qay1
Qay1
Qay1
Qafo?
QTsf
QTsf
310000
313000
312000
02'30"
314000
107°00'00"W
Qao1
MAP SYMBOLS
Base map from U.S. Geological Survey 1965, from photographs taken 1964, field checked in 1965.
Polyconic projection. 1927 North American datum. Reprojected to UTM projection -- zone 13.
1000-meter Universal Transverse Mercator grid, zone 13, shown in blue.
1:24,000
1
1000
MN
SOUTH
BALDY
MOLINO
PEAK
0.5
0
A
0
1000
2000
3000
A'
1 MILE
4000
5000
6000
7000 FEET
!
!
68
!
!
!
LUIS
LOPEZ
1
0.5
0
1 KILOMETER
NEW MEXICO
PUERTECITO
GAP
CIENEGA
RANCH
INDIAN WELL
WILDERNESS
!
!
!
CONTOUR INTERVAL 20 FEET
NATIONAL GEODETIC VERTICAL DATUM OF 1929
!
HICKMAN
RANCH
FORT
CRAIG
SAN
MARCIAL
QUADRANGLE LOCATION
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, New Mexico
87801-4796
Magnetic Declination
August, 2012
9.12132º East
At Map Center
New Mexico Bureau of Geology and Mineral Resources
Open-file Geologic Map 239
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, (L. Greer Price, Director
and State Geologist, Dr. J. Michael Timmons, Associate Director for Mapping Programs).
!
Geologic contact. Solid where exposed or known, dashed
where approximately known, dotted where concealed; queried
where uncertain.
Normal fault, ball-and-bar on downthrown side. Solid where
exposed, dashed where approximately known, dotted where
concealed. Tick gives attitude of fault plane, showing dip
magnitude, arrow gives trend of fault plane lineations,
showing plunge magnitude.
Reverse fault, teeth on upthrown side. Solid where exposed,
dashed where approximately known,
dotted where concealed.
Caldera margins, well located, approximately located,
concealed. Single tick - exhumed caldera topographic wall
circa eruption of Hells Mesa Tuff (32.3 Ma). Double tic exhumed caldera wall.
63
Strike and dip of inclined bedding.
50
Strike and dip of igneous foliation.
23
[575] 835-5490
This and other STATEMAP quadrangles are available
for free download in both PDF and ArcGIS formats at:
June, 2013
by
Colin T. Cikoski 1, Susan J. Roth 2, and G. Robert Osburn 3
1
New Mexico Bureau of Geology and Mineral Resources, 801 Leroy Place, Socorro, NM 87801
2
Roth Consulting, 6236 27 th Avenue, Seattle, WA 98115-7114
3
Earth and Planetary Science Department, Washington University, St. Louis, MO 63130
COMMENTS TO MAP USERS
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 are based on 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.
The map has not been reviewed according to New Mexico Bureau of Geology and Mineral
Resources standards. Revision of the map is likely because of the on-going nature of
work in the region. The contents of the report and map should not be considered final
and complete until reviewed and published by the New Mexico Bureau of Mines 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. Crosssections are constructed based upon the interpretations of the authors made from geologic
mapping, and available geophysical (regional gravity and aeromagnetic surveys), 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.
Qary
Qasu
Qpy
Qay
Qay
Qafu
middle upper
lower
Pleistocene
Spears Group, undivided — Interbedded conglomerate and sandstone with abundant andesitic material and no rhyolitic material.
Beds are poorly to very poorly sorted with angular to subrounded clasts, and dominantly pebble to cobble in size but locally
bouldery. Clasts are of plagioclase-pyroxene porphyry lavas, similar to the lavas of Willow Springs, with subordinate aphyric lavas
and rare to locally abundant white amphibole porphyry lavas. Generally very poorly exposed.
Ts
Eocene to Oligocene Intrusive Igneous Rocks
Rhyolitic intrusions — Fine-grained, flow-banded cliff-forming rhyolitic plugs. Phenocrysts of subhedral quartz occupy up to 2%
of the rock masses, with trace biotite and magnetite. Flow foliations pronounced and commonly contorted.
Tir
Tid
Intermediate dikes — Plagioclase ± pyroxene porphyry dikes, 0.25 to 1 m thick.
Older alluvium, older subunit (upper Pleistocene) — Matrix-rich conglomerate with pebbles and cobbles and strongly
developed soils. Gravels are subequal fine and medium pebbles to weakly fine pebble-dominated, with up to 30% coarse
pebbles and 5% cobbles. Matrices are poorly sorted silty fine to coarse sand, with colors of 5 YR 4-5/6 measured. Carbonate
horizon development up to Stage III+, with rare fine bridging clay films outside of the carbonate horizon. 2 to 4(?) m thick.
Qpy
References
Qpyh
Younger piedmont alluvium, younger subunit and historic alluvium, undivided (Holocene to Historic) — Used where
map units Qpy2 and Qah cannot be separated at the given map scale.
Baldwin, B. 1963, Part 2, Geology: in: Spiegel, Z., and Baldwin, B., eds., Geology and water resources of the Santa Fe area, New
Mexico, U.S. Geological Survey Water-supply Paper 1525, p. 21-89.
Younger piedmont alluvium, younger subunit (Holocene to Historic) — Typically matrix-rich conglomerate with pebbles
and cobbles and weakly developed soils. Dominantly fine pebbles, with up to 20% each of medium and coarse pebbles and
a few percent cobbles, in weak planar tabular beds and paleochannel lenses. Fines are silty fine to coarse sand, with poorly
sorted angular to subrounded grains. Carbonate horizon development typically Stage I. Matrix colors of 7.5 YR 6/3-4 and
4/4 measured. Up to 1.5 m thick.
Birkeland, P. W. 1999, Soils and geomorphology: New York, Oxford University Press, 430 p.
Qpy2
Qpy1
Qpo
Cather, S. M., Chamberlin, R. M., and Ratté, J. C., 1994, Tertiary stratigraphy and nomenclature for western New Mexico and eastern
Arizona: N.M. Geological Society, 45th Field Conference Guidebook, p. 259-266.
Chapin, C. E., McIntosh, W. C., and Chamberlin, R. M., 2004, The late Eocene-Oligocene peak of Cenozoic volcanism in southwestern
New Mexico: in: Mack, G. H., and Giles, K. A., eds., The geology of New Mexico: A geologic history, New Mexico Geological
Society, Special Publication 11, p. 271-294.
Younger piedmont alluvium, older subunit (upper Pleistocene to Holocene) — Matrix-rich conglomerate with pebbles
and cobbles and moderately well-developed soils. Dominantly fine to medium pebbles, with up to 30% coarse pebbles and
10% cobbles. Weakly planar tabular bedding with local paleochannels. Matrix is poorly sorted silty fine to coarse sand, with
colors of 7.5 YR 4/4 and 7/3 measured. Carbonate horizon development typically Stage II. Up to 2 m thick.
Chamberlin, R. M., and Cikoski, C. T., 2010, Preliminary geologic map of the Indian Well Wilderness quadrangle, Socorro County,
New Mexico: New Mexico Bureau of Geology and Mineral Resources, Open-file Geologic Map OF-GM-201, scale 1:24,000.
Older piedmont alluvium (upper Pleistocene) — Matrix-rich conglomerate with pebbles and cobbles and strongly
developed soils. Deposits are dominantly fine pebbles and lesser medium pebbles, with coarse pebbles, cobbles, and sparse
boulders concentrated in rare paleochannels. Matrices are muddy fine to coarse sands to fine sandy muds, with colors of 5
YR 5/3-4 and 7.5 YR 6-7/4 measured. Carbonate horizon development typically Stage III+, with local well-indurated pockets
within an otherwise poorly indurated horizon. Clay films highly variable; locally abundant as fine to coarse pore linings,
but commonly rare and fine as gravel coats. 1-3 m thick.
Qafu
Qafo
Chamberlin, R. M., McIntosh, W. C., and Eggleston, T. L., 2004, 40Ar/39Ar geochronology and eruptive history of the eastern sector
of the Oligocene Socorro caldera, central Rio Grande rift, New Mexico: in: Cather, S. M., McIntosh, W. C., and Kelly, S. A.,
eds., Tectonics, geochronology and volcanism in the southern Rocky Mountains and Rio Grande rift: New Mexico Bureau of
Geology and Mineral Resources, Bulletin 160, p. 251-279.
Exposure of the Socorro caldera wall at the time of the eruption of the La Jencia
Tuff. Backpack lies on the contact, with the La Jencia Tuff lying to the left (northeast)
and pre-caldera porphyrytic andesite lavas of Willow Springs lying to the right.
Attitude of contact is 60° to N66E (dip, dip direction). Foliations in the basal La
Jencia Tuff parallel this contact, grading up-section to a gentler eastward tip.
Quaternary Alluvial Fan Deposits
Strike and dip of igneous foliations for multiple observations
at a single locality.
Paleocurrent sediment direction determined by clast
imbrication.
Spears Group (sensu Cather et al., 1994)
Younger piedmont alluvium, undivided (upper Pleistocene to Holocene) — Used where map units Qpy2 and Qpy1 cannot
be reliably subdivided.
Minor fault, tick gives attitude of fault plane, showing dip
magnitude, arrow gives trend of fault plane lineations,
showing plunge magnitude.
3
Andesite lavas of Willow Springs — Medium to dark gray, reddish gray, and dusky red, plagioclase ± pyroxene andesite porphyry
lavas. Lavas contain 20-40% phenocrysts, dominantly of white, often chalky, tabular plagioclase 3-7 mm across, with subordinate,
but locally abundant, prismatic black pyroxene crystals 1-7 mm across. Individual flows are 3-20 m thick. Map unit contains small,
unmappable areas of unit Ts.
Twl
Quaternary Piedmont Alluvial Deposits
Location of geologic cross section.
Andesite dike, unit Tid, tick showing dip.
85
Geologic map of the Cienega Ranch
quadrangle, Socorro County, New Mexico
http://geoinfo.nmt.edu
87
!
Lower La Jencia Tuff — White to tan, lithic-rich, crystal-poor, variably welded tuff. Up to 50% lithic fragments, principally of
aphyric andesitic material, with sparse crystal-rich, quartz-bearing rhyolites. Rare phenocrysts (up to 5%) of fine (up to 2 mm across)
clear tabular sanidine. Where well-exposed, grades upsection into unit Tlj. May be in part or entirely correlative to unit Tzt, with the
gradational contact resulting from inter-tuff welding.
Tljl
Qay1
33°45'00"N
309000
308000
05'00"
Qay
?
33°45'00"N
QTsf
Qafo
Qasu
Qasu
Qay2
Qah
QTsf
Qafo
Qasu
?
QTsf
Qay1
Qsa
Qay2
Qafo
Qay1
?
af
Qafo
Qay1?
QTsf
Qafo?
Qay
?
QTsf
Qafo
Qay2
Qay
Qafo
Streamcut exposure of Qao2 over QTsf clayey sand. Brownish gray gravel at the top
of the outcrop belongs to map unit Qao2. Note Stage III carbonate horizon at the
top of this unit. Light brown to pale reddish brown fine-grained sediment beneath
is clay-rich and belong to QTsf; this almost exclusively fine-grained facies of QTsf
is only.
Qay1
?
Qah
QTsf
Qafo
Qasu
QTsf
Qay
Qay
?
?
Qsa
Qay1
Qay1
QTsf
Tuff of Rocque Ramos Canyon — Light gray to light brownish gray, phenocryst-rich, moderately lithic-rich, pumice-poor,
moderately to densely welded ignimbrite. Contains 15-20% phenocrysts principally of clear to white, tabular sanidine <1-5 mm
across, with local, subordinate, black to coppery biotite crystals up to 2 mm across. Lithics occupy up to 5% of the rock and are of
andesitic material up to 2 cm across. Rare pumice fragments are moderately to strongly flattened and up to 5 mm long. Correlation
based on similarity to an ignimbrite on the Indian Well Wilderness quadrangle. 40Ar/39Ar date is 35.32 ± 0.14 Ma (Chamberlin and
Cikoski, 2010).
Trr
La Jencia Tuff — Light gray to reddish gray, crystal-poor, lithic-poor, densely welded rhyolitic ignimbrite. Phenocrysts are typically
<2% of the rock, though locally up to 5% low in the unit, and are dominantly clear, tabular sanidine up to 2 mm across. Sparse quartz
and biotite also present. Lithics are 0-2%, typically of andesitic material, with sparse crystal-rich rhyolites. Middle portion of the
unit is diagnostically strongly flow-foliated, imparting a red-and-gray striping to outcrops. Lithophysae are locally abundant near
the base.
Tlj
Qay
Qay
?
Qay2
3737 000
Hells Mesa Tuff — White to light brown to light gray, poorly to densely welded, crystal-rich, quartz-rich, pumice-poor ignimbrite.
Phenocrysts are abundant (20-40%), with common quartz up to 5 mm across, lesser tabular sanidine and plagioclase, and rare
biotite. Generally lithic-poor, but locally lithic-rich. Not separated into inter- and intracauldron facies here as diagnostic criteria
were not observed in the field.
Thm
Vicks Peak Tuff — White to tan, crystal-poor, lithic-poor, pumice-rich, moderately to densely welded rhyolitic ignimbrite.
Phenocrysts are up to 5% of the rock, dominantly of subhedral, clear, tabular sanidine, with sparse quartz. Pumices are locally
coarse, up to 20 cm across observed, and commonly replaced by vapor-phase quartz and sanidine, imparting a sugary texture
surrounded by a light-colored, fine-grained rim. Generally poorly exposed on this quadrangle.
Tvp
Qay
Qasu
?
Qpo
Tuff of Caronita Canyon, lower member — Light gray to medium red, crystal-poor to moderately crystal-rich, pumiceous, poorly to
densely welded tuff. Phenocrysts are 3-20%, increasing up-section, and dominantly of plagioclase, with lesser biotite and magnetite,
and sparse sanidine, quartz, pyroxene, and amphiboles.
QTsf
Qay
Qay
Qafo
Qah
?
Qafo
Qay2
Qafo
?
22
Qafo?
?
23
Qsa
QTsf
Qao 2?
Qay1
?
?
Qay2
Qay
?
?
QTsf
Qah
Qay1
Qay1
?
Qasu
Tccl
?
Qafo
Tccu
Tuff of Caronita Canyon, upper member — White to medium gray and locally pale red, crystal-rich, pumiceous, poorly to densely
welded tuff. Phenocryst content is 30-40%, and dominated by subequal amounts of subhedral sanidine and coarse, commonly
bipyramidal quartz, with lesser biotite and sparse plagioclase.
Qay2
?
?
QTsf
QTsf
Qay1?
Qafo?
Qay
Qay2
Qah
Qay2
?
Qay2
Qah
Qay
?
Qao
Tuff of Caronita Canyon — Divided into lower and upper members based on phenocryst abundance and composition:
Datil Group, undivided — Used in cross-section only. May include any combination of the below units, and possibly others not
exposed at the surface.
Tdu
Lemitar Tuff — Light gray to medium red, generally crystal-rich, pumice-poor, lithic-poor, moderately to densely welded rhyolitic
ignimbrite. Phenocryst content increases up-section from 5 to 40%, though in this study area the tuff is more often than not crystalrich (25-40%). Phenocryst composition is variable, but commonly consists of abundant sanidine, rare to common quartz, rare
plagioclase, and sparse biotite, with phenocrysts 1-3 mm across.
3738 000
Qay1
Qao 2?
Qay1
Tlj
61
Qay
Qafo
Qay1
La Jara Peak basaltic andesite lavas — Medium to dark gray to purplish gray, fine-grained lavas. Phenocrysts are up to 8% of flows,
principally of mafic crystals reduced to reddish brown to orange iron oxides, with sparse white, chalky plagioclase crystals. Both
are <1 mm across.
Qao 2
?
Qay
Qafo
af
Qay2
26
3737000
Qao1
?
QTsf
Qay1
34
QTsf
Tlj
Qay2
?
Qay1
Qay2
Tlp
Qay2
?
Qpo
Qah
?
Qay1
25
QTsf
Qafo
?
QTsf?
Qca
?
?
Qay2
Tl
Tvp
Qasu
Qpy1
South Canyon Tuff — Light gray to tan, crystal-poor to moderately crystal-rich, pumiceous, moderately to densely welded rhyolitic
ignimbrite. Phenocryst abundance increases sharply up-section from 2-4% to 20-25%, and consists throughout of subequal quartz
and sanidine, 1-3 mm across and subhedral, with minor plagioclase and biotite.
Qay2
Qai
Datil Group (sensu Cather et al., 1994)
Tsc
Tl
Qao 2
?
?
Qay1
?
Qay
Qafo
Qah
?
Qsa
Qpy2
Qah
Older alluvium, younger subunit (upper Pleistocene) — Matrix-rich conglomerate with pebbles and rare cobbles and
strongly developed soils. Deposits are dominantly fine pebbles with up to 20% medium pebbles and rare coarse pebbles
to sparse boulders. Matrices are up to 40% of deposits, consisting of poorly sorted silty to clayey fine to coarse sand, with
colors of 5 YR 5/4-5/6 and 6/4, and 7.5 YR 5/3 and 4/4 measured. Carbonate horizon development up to Stage III, with
common fine to medium clay films as gravel coats and bridges outside of the carbonate horizon. 1.5 to 4(?) m thick.
Qao 2?
Qafo
Tza2
Mogollon Group (sensu Cather et al., 1994)
Older alluvium, undivided (upper Pleistocene) — Used where Qao1 and Qao2 cannot be distinguished reliably. Deposits
are similar to Qao1 and Qao2, as described below.
Qay1a
?
Qasu
Andesitic lavas — Pale brown to light brownish gray, with variable greenish colors from alteration, plagioclase-pyroxene andesite
porphyries. Tza is up to 10% phenocrysts of subequal plagioclase and pyroxene, up to 0.5 mm across, with rare biotite. Tza2 is 1520% phenocrysts of plagioclase up to 1 cm across, with rare (up to 5%) pyroxene up to 1 mm across. Sparse biotite and amphibole
crystals.
Tza
Eocene to Oligocene Volcanic and Volcaniclastic Rocks
?
Qao1?
?
Qay
31
Qao 2
Qafo?
Qay2
Qah
Qsa
Intermediate-aged alluvium, undivided (upper Pleistocene) — No exposure observed. Used to designate terraces with
treads between those of Qao2 and Qay1a, which only occur locally. Surface examinations indicate a gravel-rich unit, with
poorly sorted pebbles to boulders. Soil development evident as reddening of surface gravels. Thickness unknown, but
probably <1-2 m thick.
Qay2
Qay
QTsf
QTsf
Qay
Qay2
Qpy1
Qsa
Qay2
Basal Santa Fe Group (Miocene) — Reddish brown to red, matrix-rich conglomerate. Conglomerate grades up-section from matrixsupported, massive, unsorted mudflow deposits to stratified, matrix-rich, poorly sorted conglomerates. Beds are typically wellindurated, and dominated by clasts of the Lemitar Tuff (Tl).
Tsfb
Qao 2
?
Qpy1
QTsf
?
?
Qah
Qay2
Qah
Qao2
Qay2
Qao1
Qay
3739 000
Qai
?
?
Qay2
Qay2
30
Qah
Qafo
?
Qah
Qpy1
3738000
46
Twl
Qao1
Qafo
Qao
Qao 2
Qai
Qay2
Qay
Qca
Qpo?
Qay1
Qay
Qay2
Qpo
3739000
?
?
Tlj
Qay
Qasu
Qsa
Lower Santa Fe Group (Tsfl) conglomerates. Dips this steep (here, 16° to S30E)
have not been observed in any overlying strata.
Twl
Qay2h
Qay2
af
Exposure of Qay1as sediments. Cobbly gravels at base belong to QTsf. Fines above
are silty sands grading up-section to muds, which grade laterally into cobbly Qay1a
sediments.
Qpo
Qay1
Qah
af
Qay
?
Qah
3740000
Qasu
Tzs
Qpy1
QTsf
Qay2
21
?
Qay1
Volcaniclastic sedimentary rocks — Conglomerate and sandstone bearing common andesitic material and rare rhyolitic material.
Beds are poorly to very poorly sorted, with angular to subrounded gravel comprised predominantly of pebbles but with rare
cobbles and sparse boulders. 0-40% rhyolitic material, commonly of sandine-rich porphyries, but with rare aphyric, strongly flowbanded rhyolites. Sandstones and conglomerate matrices are very poorly sorted wackes, with clay to coarse sand grains, angular to
subangular. Individual beds are 20-50 cm thick.
Qpy2
Twl
af
Qay2
Tzrb
47'30"
Qay2
Qao
Qah
Qay
Qpo
Qpy1
Twl
QTsf
Qay2
Rhyolitic breccia — Light gray to light pink to light reddish brown breccia of flow-banded, phenocryst-poor rhyolite. Clasts contain
1-2% phenocrysts of sanidine up to 1 mm across. Individual breccia blocks are 1 to 20 cm across, angular, and densely packed with
local “jigsaw” textures. Rare xenoliths of andesitic material and white rhyolites.
Qay2
Qay1
Qay1
3741 000
Qpyh
Qah
Qay1b
Qay1b
Qay1
af
Qay2
Qpo
Qay1
Qao
Qay1a
Qsa
Qpy1
Qah
Qay1b
Upper portion of the tuff of the Luis Lopez Formation. Mottled white and pink
rock under hammer is pumice-rich and moderately lithic-rich tuff, while overlying
thinly bedded material is tuffaceous sandstone. Here, the tuff underlies ringfracture rhyolite domes (map unit Tzr), which in turn underlies the La Jencia Tuff.
Qpy1
Qah
QTsf
Qay1b
Qay1
af
Qpy1
?
Qah
Qasu
Qpo
Qao
Qay2 Qay2 Qafu
Qay2
Qay
Qay1
Qao
Qpy1
Qay2
af
Qay2
3742 000
Qah
QTsf
Qasu
QTsf
Qay2
Qay2
47'30"
Younger alluvium, older older subunit, sandy silt facies (early to middle Holocene) — Silty sands grading up-section
to sandy muds and forming a fine-grained cap on pebbles and cobbles of unit Qay1a. Fines are moderately thinly planar
bedded (beds up to 6 cm thick), with sparse fine pebbles up to 2 cm across. Colors of 10 YR 8/1 and 2.5 Y 8/2 measured. Clay
films found toward the top, as common fine-sized gravel, ped face, and pore linings. 0.5-1.5 m thick.
Qpy1
Qay1a
Qasu
Lower Santa Fe Group (Miocene to Pliocene) — Pale to medium brown conglomerate, pebbly sandstone, and sandstone.
Conglomerates are poorly sorted and subangular to subrounded, dominantly of pebbles with rare cobbles and sparse boulders up
to 30 cm across. Gravel compositions are dominated by rhyolites of various textures, reflecting the textures of the various major
ignimbrite units. Rare (up to 3%) andesitic material and sparse (up to 1%) aphyric basaltic material is also present, as are trace
recycled volcaniclastic sedimentary gravels. Sandstones and matrices are poorly sorted silty fine to coarse sand. Locally interbeds
with white ash fall and reworked ashy material. Likely correlative to the Popotosa Formation.
Tsfl
Qpy1
?
3741000
Qay1a
Qay1b
Qay2
Qay1
Twl
Qay
?
Qao?
Qasu
QTsf
Qay1
Ts
Tir
Qpo
Qsa
Qao
Qay1
?
Qao
Qay1b
?
QTsf
Qay1
?
?
?
?
?
Twl
Qay1b
Qay1a
af
Qao?
Ts
Tdu
Qca
Qpy1
Qay
Qay2
Qasu
Thm
Tljl
Qay2
Qay2
Qay2
?
Qay
Qah
Twl
Qpyh
QTsf
Qay1a
Qasu
Qay
Qafu
Qay1b
Qsa
Qah
Qay2
Qay2
Tlj
Tlj
?
?
?
?
?
?
Qasu
?
Qay1
Qasu
Qsa
Qay1
Qao?
Qasu
Qay1as
Tzs
Tza
?
?
af
Qay1
Qao
3742000
?
Qasu
Tvp
40
7
Qah
3743 000
4
Tlj
Qay2
15
Tza2
Tir
Qpy1
Qay1b
Qay1a
Qsa
?
Qay
Qay2
Qay1a?
?
Qay2
9
Qay1a
Qay1
Qay1
Qay1b
Qay2
?
Qay1
Qay2
Qay2
Qsa
?
Qay2
?
?
Qay1
Qah
Qay1
Qsa
11
15
20
Qpy1
?
?
Qay1
25
Tsfl
?
?
?
Qasu
Qpo
Tccl
Tvp
Tzrb
Tzt
Upper Santa Fe Group (Pliocene to lower Pleistocene) — Clay-rich gravel and silty sand to sandy silt. Gravel beds dominate, and
consist of poorly sorted fine to medium pebbles with up to 40% coarse pebbles and up to 15% cobbles and rare boulders. Matrices
are rich in pale to medium red clays, both as aggregated chips and as medium to coarse films on gravel faces and bridging sand
grains. Clay-rich fine to coarse sand beds are discontinuous and thin, increasing in abundance to the south. Matrix colors of 2.5 YR
5-6/6 and 5 YR 5-6/4-6 measured away from carbonate horizons; colors of carbonate horizons include 5 YR 8/3, 7.5 YR 9/2, and 10 YR
9.5/1. Carbonate horizon development in buried soils up to Stage III; active soil typically bears a Stage IV horizon.
QTsf
Exposure of Qay1a/Qay1b buttress unconformable contact. Brownish gray, crossbedded conglomerate to right of center (south) belong to Qay1b, which is inset upon
Qay1a and QTsf sediments to the left of center. The Qay1a/QTsf contact lay at the base
of the white carbonate horizon, which here has Stage III morphology, a level of
development likely enhanced by the presence of less permeable QTsf sediments
immediately below the horizon.
Qpy1
Qpy1
Qay1a
Qasu
?
Twl
Qsa
Qay2
?
?
Qay1a
Qay
38
Qay
Qay
Qay1a
Qay2
Qca
Trr
Tlj
Qay1b
QTsf
Qay2
Qay1
Tl
Tzr
Tuff of the Luis Lopez Formation — White to tan, very lithic-rich, moderately pumice-rich, crystal-poor, variably welded tuff. Tuff
is 20-50% lithic fragments, principally of aphyric basaltic to andesitic material, with lesser andesite porphyry, and sparse crystalrich, quartz-bearing rhyolite. Lithics are up to 5 cm across. Sparse phenocrysts of fine (up to 1 mm across) sanidine and lesser
quartz. Small (up to 2 cm across) flattened pumices are variably rare to common. Where directly underlying unit Tlj, may be in part
or entirely correlative to unit Tljl.
Tzt
Sedimentary fill of Miocene to Pleistocene rift basins associated with the Rio Grande rift (Baldwin, 1963; Hawley et al., 1969).
Subdivided based on age inferred from cementation, bedding attitude, and stratigraphic location.
Tlj
Tsc
Qpo
Qay2
Qsa
Qay1
Qah
Qao 2
QTsf
QTsf
?
39
Twl
Qay1a
?
?
?
3743000
Qay1a
?
Qay1
11
Tvp
Qah
Qay2
Qay1
Qsa
22
?
Qay1
Qay1?
Twl
Tlj
Qafu
Qay1
Qsa
Qasu Qay1b
Qay2h
Tvp
Qafu
Qafu
?
?
Tlj
Qay1
27
Qay1b
Qay1
Qay
Qsa
Qah
Qay
Tlj
Qafu
Qsa
Qca
Tl
Tccu
56.0
Santa Fe Group
3744 000
Tlj
Qpy2
Qay2
Miocene to Lower Pleistocene
Twl
Qpy1
Qary2
?
Qay1b
Qasy
Qay1a
Qay
Qah
?
3744000
QTsf
?
Qasu
Qay1
Qsa
?
Qay
Qpy2
Tlj
Qpy2
60
Qpo
Qpy1
Qay1a
Qay
Qah
36
55 8
Qpo?
Qay2
Qay1b
Qpo
Qpo
Qpy2
Intrusive Rocks
Trr
Older Ryan Canyon fan alluvium (upper Pleistocene) — Sandy pebbles with age marked by red color and clay accumulation in
the matrix. Gravels are poorly sorted pebbles, mostly fine pebbles with 15-25% medium-coarse pebbles, <1-1% cobbles, and sparse
boulders. 15-30% matrix of clayey fine to coarse sands. Clay occurs as uncommon medium to coarse films coating gravels and
bridging grains. Matrix color of 5YR 5/8 measured. 0-3(?) m thick.
Qaro
Volcanic/
volcaniclastic Rocks
Qaro
Tsc
Tlp
Younger Ryan Canyon fan alluvium , older subunit (upper Pleistocene) — No exposures observed, but surface examinations
indicate a gravel-rich unit, with poorly sorted pebbles to cobbles. Small scale relief is subdued, with some relict bars distinguishable.
Surface vegetation is dominantly of grasses, with lesser shrubs. Soil development evident in common reddening on surface gravels,
particularly cobbles. 0-3(?) m thick.
Qary1
Qafo
Tsfb
33.9
Younger Ryan Canyon fan alluvium , younger subunit (Holocene) — No exposures observed, but surface examinations indicate a
sand- and gravel-rich unit, with poorly sorted pebbles to cobbles. Some small-scale relief as bar-and-swale topography is preserved,
but smoothed relative to Qarh. Surface vegetation is a mix of shrubs and grasses, with grass cover increasing down-gradient. 0-2(?)
m thick.
Qca
Qpo?
Qpo
Qay1b
Qay1a?
??
Qay1b
Qay1b
Qpy1
Qay1b
Younger Ryan Canyon fan alluvium, univided (upper Pleistocene to Holocene) — Used where map units Qary2 and Qary1 cannot
be reliably distinguished.
11
Qpo
?
Thm
Qafu
Qary1
Qay1b
Qasu
Qah
Qasu
Tlj
Twl
?
Qay2
Qao
Historic Ryan Canyon fan alluvium (Holocene) — No exposures observed, but surface examinations indicate a sand- and gravelrich unit, with poorly sorted pebbles to rare boulders. High small-scale relief as bar-and-swale topography and pool-and-riffle
stream channel morphology. Surfaces have poor grass cover, but common to dense shrub cover. No evidence of soil development.
0-2(?) m thick.
Qarh
3745 000
Qpy2
?
Qay1b
Younger alluvium, older older subunit (early to middle Holocene) — Massive sand, pebbles, and cobbles. Poorly to very
poorly sorted deposits, up to 10% cobbles with common coarse pebbles and abundant medium to fine pebbles. Matrices
of poorly sorted silty very fine to fine sand with up to 15% medium-coarse grains, with clay as rare fine films on gravels.
Moderately well-developed soils. Colors of 7.5 YR 4/2-6/2 and 5 YR 5/6 measured. Carbonate horizon development up to
Stage II, with local Stage III horizons occurring where directly overlying less permeable units. 0.5-1 m thick.
Qpo
Qary1
QTsf
23.0
Ryan Hill Canyon fan
Qary2
Qpo
Qay2
Qay1
?
Qafu
Younger alluvium, younger older subunit (upper Pleistocene to early Holocene) — Cross-bedded conglomerate with fine
to medium pebbles with lesser coarse pebbles and a few percent cobbles with moderately well developed soils. Poorly to
moderately sorted gravels, with clayey to silty fine-medium sand matrices; clay as rare very fine to medium-sized films on
gravels and bridging sand grains. Matrix colors of 5 YR 5/4-6/4 measured in clay-rich horizons, and 7.5 YR 6/3 measured
outside these horizons. Carbonate horizon development as strong as Stage II. 1-2 m thick.
Qpy1
Qarh
Qary2
Tsfl
Undivided Sawmill Canyon fan alluvium (upper Pleistocene to Holocene) — Interbedded pebble to cobble conglomerate and
silty sand. Gravels are dominantly matrix-poor fine pebbles with common medium pebbles, up to 20% coarse pebbles, and up to 5%
cobbles. Sands are discontinuous lenses that are poorly sorted, variably clayey and silty fine to coarse sand. Clay as rare to common
fine to coarse films on gravels and bridging grains. Matrix colors of 5 YR 4/4-6 and 6/3, and 7.5 YR 5-6/4 measured. Carbonate
horizon development up to Stage I in buried soils. 2-5(?) m thick.
Qasu
Qpy2
Qah
Qay
Qao
Qpo
?
Qsa
Qay2
Younger alluvium, older subunit (upper Pleistocene to Holocene) — Used where Qay1a and Qay1b cannot be distinguished
reliably, either due to the given map scale or to weak map unit indicators.
50'00"
Qpo
?
Qasy
11
Thm
Twl
QTsf?
5.33
Younger Sawmill Canyon fan alluvium (Holocene) — Interbedded pebble beds, sand beds, and cobbly fills of paleochannels with
weakly developed soils. Pebble beds are planar bedded and dominantly fine pebble-sized, while paleochannels bear common coarse
pebbles and rare cobbles. Sand beds are discontinuous, muddy fine to coarse sand, with colors of 5 YR to 7.5 YR 5/4 and 7.5 YR 6/3
measured. Carbonate horizon development as strong as Stage I, with locally common clay films as fine gravel coats. 1-3 m thick.
Qary
Tzt
Qay
Qary1
Qsa
? Qay1b
Qao 2
Tzs?
Sedimentary
Rocks
Qay1as
Qao2
Qao1
Qao
Sawmill Canyon fan
Younger alluvium, younger subunit (Holocene) — Pebbly sand to silt and sandy gravel with weak soil development.
Gravel beds are typically poorly sorted pebbles with a few percent cobbles in massive matrix-rich beds. Fines are very fine
to medium sands and silts, with colors of 7.5 YR 5/3-6/4 and 10 YR 6/4 measured. Carbonate horizon development up to
Stage I+. Bar-and-swale topography typically apparent on terrace treads. 1-3 m thick.
Qah
Qpo
Qpo?
Qay2 Qay1?
Qay
Twl
Qpy1
Qaro
?
Qao?
Qay
Qpo
Roadcut exposure of QTsf gravels along the Ryan Hill Canyon drainage. Note the
well-developed carbonate horizon at shallow depth; laminae can be found at the
top of this horizon, indicating a Stage IV morphology. Underlying gravels bear a
clay-rich matrix.
Thm
Qpy2
Qay1b
Qah
Qay2
?
af
3746 000
Qca
2.59
Twl
Qay1a
Qaro
Qay1a
Ts
Ts
Qpo
?
af
Qay
Trr
QTsf
Qpy1
9
Qpo
Trr
Qpo?
Twl
Qao
Qay2
50'00"
34
QTsf
22
Trr
QTsf
Qary1
Qay2
Twl
QTsf
Qay2
Qary2
Tlj
Qpo
Qpy1
Qpy1
Qary2
Qaro
Qary
?
Qay1
Qao 2
Qay
Qay1b
Qpo
Qpy1
Qay1
Qay1
Qpy
Ts
Qah
?
Qay2
Qai
?
Qay1
Trr
QTsf
Qay2 Qah
3747 000
Tzt
Twl
Qah
Qpy1
Qay2
Qary1
30
Qpy1
Qpy1
Qarh
Qaro
Qpy1
Ts
Qay
QTsf?
Twl
Qpy1
71
Qca
Twl
Twl
Qaro
?
Qsa
Qaro
Qpy1
Qay2
Qary1
Younger alluvium, younger subunit and historic alluvium, undivided (upper Holocene to Historic) — Used where the
two cannot be mapped separately at the given map scale.
Qca
Twl
Qpo
QTsf
Qpy1
Qaro
?
Qay2h
Qay2
Twl
QTsf
Trr
Twl
20
Qpy2
af
Qay1
Qasu
Qay1a
Qary2
Qaro
Qao
Qay2
Qao?
27
11
Trr?
Qay1a
?
Qah
Qah
Qay2
Qaro
Qay1
Qpy1
Qay2
?
Qpy1
Twl
QTsf
Qay1b
Twl Tzt
Twl
Qpy1
Qao
Qaro
Qary
Qaro
Qpy2
?
Qah
Qay1a
Qpy2
Qca Tzt
Thm
Trr
Ts
Ts
Twl
Tlj
?
Qay
Qao1
Qao1
Qay1?
41
?
Qay
Qao
?
Qay2?
?
af
?
QTsf
Qay1b
Qay
Qary1
Ts
Qpy2
QTsf
Qay
Qaro
Qah
Qah
Qay
Qay2
af
30
Tid
Qaro
Tlj
10
68
87
Qaro
?
QTsf
Twl
Qay2
Qarh
?
Younger alluvium, undivided (upper Pleistocene to Holocene) — Used to designate narrow, typically shallow drainages
where Qay1 and Qay2 cannot be distinguished reliably, and cannot be mapped separately from Qah at the given map scale.
Up to 2 m thick.
QTsf
Qpy
Twl
Qaro
Qay1b
?
Qay2
Qay
QTsf?
Qay
QTsf
Qay1
Qao
?
Qay
QTsf
Trr
?
Qay1
Thm
Qary1
Qary1
Qay1
Qay
Qay1a
QTsf
Historic alluvium (subject to annual deposition) — Boulders to fine sand along active stream channels exhibiting evidence
of historic transport, including no soil development, little vegetation cover, and surfaces with high small-scale relief. 0-3(?)
m thick.
26
41
Tzt
Twl
Twl
?
Qay1b
af
Qpy
Qah
3748 000
10
Tzs
Qca
QTsf
Qah
Qaro
Qay1b
Tl
Twl
Qay2
QTsf?
Qay2
?
Qay
Qaro
Qay1a
QTsf
Qah
Qay
23
Tzs
Thm
?
Qaro
Qaro
?
QTsf
Qah
Qay
Qpo
Trr
Twl
1.806
Note: All alluvial units typically fine to the south (away from the Magdalena and Chupadera Mountain sources), and soils
typically grade from more carbonate/less clay in the southern, lower elevation areas to more clay/less carbonate in the
northern, higher elevation areas.
29
Qpo
Thm
13
QTsf
Tl
Qpy2
QTsf
?
Qay
3747000
Qaro
Qaro
Qay1b
Qah
Tzs
Tljl
?
Qah
Qay2
Qay QTsf?
Qaro
Qay2
Tsc
Tvp?
Qay2
Qay
Qay1a
Qay1
?
Twl
Tzs
Qca
Tl
Tljl
Qca
Quaternary Alluvial Deposits
Tzr
Qpo
Ts?
0.781
Tlj
Tzt
Tzs
Qpy
20
Qay2
Qay2
Qay1
QTsf
Qary1
?
Qao 2
Tl
Qah
Qay
Tlj
QTsf
Qary1
QTsf
Qay
Qay2
Qay2
2
?
Qah
Qay1a
QTsf
?
Tsfl
Qay1b
Qaro
Qay1b
Qay1a
Qay2
Tl
Qay1b
Qay
Tsfl
20 Tvp
af
Qpo
Tzt
Colluvium and alluvium, undivided (upper Pleistocene to Holocene) — Proximal deposits of silt to boulders. Only
mapped where concealing underlying geologic relationships, or where thought to be particularly thick. 0-4(?) m thick.
Qay1
Qasy
Qpy2
Undifferentiated fan alluvium (upper Pleistocene to Holocene) — Used where multiple distributary networks overlap.
May contain alluvial elements from Torreon Arroyo, Ryan Hill Canyon, Cienega Springs, Sawmill Canyon, and smaller
drainages. No exposures observed, and age uncertain, but appears to be correlative with younger alluvial elements such as
Qay_, Qary_, and Qasy.
Gile, L. H., Peterson, F. F., and Grossman, R. B., 1966, Morphological and genetic sequences of carbonate accumulation in desert
soils: Soil Science, v. 101, p. 347-360.
Luis Lopez Formation
Volcanic and clastic fill of the Socorro caldera
Older undifferentiated fan alluvium (upper Pleistocene) — Used where multiple distributary networks overlap. May
contain alluvial elements from Torreon Arroyo, Ryan Hill Canyon, Cienega Springs, Sawmill Canyon, Copper Canyon, and
smaller drainages. No exposures observed, but surface characteristics suggest correlation to older alluvial elements (Qao,
Qaro, Qpo, etc.).
Rhyolite lavas — White to pink to tan to brown, variably spherulitic, crystal-poor, flow-banded rhyolite flows. Phenocrysts are
sparse (<1-2%) and fine (up to 1 mm across), and dominantly of sanidine, with local biotite and plagioclase. Spherulitic textures
occur throughout, generally concentrated along certain flow bands but locally dominating flows. Locally (auto)brecciated, locally
vitrophyric.
Tzr
Mapping Responsibilities
GEOLOGIC CROSS SECTION
A
A'
West Magdalena
Mountains
CTC
2,000
meters ASL
1,800
107°7'30"W
107°0'0"W
CTC – Colin T. Cikoski
GRO – G. Robert Osburn
SJR – Susan J. Roth
1,600
N90E
Tzr
? Thm
Tdu
Tsfb Tza Tza2
Tlj
Tza2 Tzr
Tza
?
Thm
500 m
Tir
QTsf
?
Thm
?
N77W N65E
QTsf
Tdu
1,400
1,200
Tir
Bend in
section
Bend in
section
N90W S77E
?
?
Tdu
Tsfl
Tsfl
Tzr
Tzs?
Tzs?
?
?
?
?
?
Tdu?
?
QTsf
Tsfl
Tsc?
Tzr?
Tzr?
? Tzt?
Thm?
Tl
Tzt?
?
?
?
Tzs?
Thm
?
?
Tdu?
Torreon
Arroyo
Western two concealed down-to-the-west faults projected from Molino Peak quadrangle;
eastern two concealed faults expected to exist, but there is no surface expression of them.
QTsf
Tlj ?
? ?
East
?
Tzs
Tzt
Tzr
Tl
Tlj
Tsfl
Tsc?
Tlj
QTsf
Tsc?
Tsc?
Tl?
Tlj
Tzr?-Thm?
Tlj
?
Tzr?-Thm?
Tsfl
?
?
?
Tl?
QTsf
Tsc?
Tsc?
?
?
Tzr?-Thm?
?
Tlj
?
?
Tl?
?
?
Tzr?-Thm?
?
?
?
Thm
Twl
Tsfl
Tl?
Tlj
?
?
Tvp
Tlp Tsc Tlj Tljl
Tl
Thm
Tljl
Twl
?
Tlj
Tlj
Tljl
Tvp
Tzrb
Tzs
Trr
Tljl
Twl
?
?
Twl
?
?
Tlj
Tzr
Tzt
Thm
Tzs
Tzt
?
?
?
Tzr
Tzt
Tzs
?
Qah
Qpy
Qay2
QTsf
Qary2
35
Thm
63
Qca
Qpyh
Qay2h
Qay1b
Qay1a
Qai
Gelasian
Qay1
31
Tlj
Tzt
Tzs
85
20
Tl
22
Tzr
Tlj
Qay1a
Qay2
QTsf
Qca
32
?
32
Qah
Tzr
Tsfl
QTsf
Tlj
Qca
Qay1
Qao
15
Qary2
Qca
Qay2
Tsc
Qay2
Qary1
Tzrb Qpy
Tlj
Tl
51 16
Qsa
3749 000
Qah
Qay2
Piedmont and
Fan Alluvium
Pliocene
28
32
Tlj
Tsfl
Tsfb
3748000
Qay
Tzt?
0.126
Qca
Miocene
Tzr
Qay1b
Qay1
Qay1
Qay2
16
Qpo?
Tlp
Slopewash and alluvium, undivided (Holocene) — Fine sand and silt with lesser medium-coarse sand and rare pebbles
occupying shallow, low gradient channels. Minimal to no soil development. 0-1(?) m thick.
Qsa
Oligocene
Qay1
Tza
Qay2h
Tzrb
0.012
Quaternary Colluvium and Slopewash
J A'
af
Stream
Alluvium
Eocene
Qao
Qay1
QTsf
Qay1
Tzt
Qay1
Qca
Qay2?
Qah
Qary1
Tvp
Qay2
Tzt
Tzs
Holocene
Quaternary
Tsfl
Qaro
Tlj
39
Qay1
Qaro
QTsf
Qay2
55
Qay1
14
Qay1a
Qay2
Qah
Qay1
Qca
Tl
Qpo?
Artificial fill — Compacted sediments, mainly of earthen dams. 0-4 m thick.
Colluvium/
Slopewash
Neogene
22
Tza 2
Tsfl
?
Tl
af
Qca
33°52'30"N
22
Qay
Qary2
Qao
22
Tza 2
Qca
Qarh
QTsf
Tlj
Tzr
Qay2
Qary2
Qay2
Qay1
Tzr
Qay
Tzr
Qay1a
Tsfl
Thm
Tl
Tsc
Tl?
Qary1
33°45'0"N
Tsfb
Qary1
QTsf
SJR
Qay1
? Qao?
Qah
Tza
Tir
3749000
Qca
Tzr
Tza 2
Qay1b
Qah
Qay2
Qay1b
Qay2
Qao
Qarh
Tlj
Qpy
GRO+CTC
J
Tlj
Tza 2
Tsfl
Qay1
Age
(Ma)
0
Anthropogenic Deposits
?
Tir
50
24
Tlj
Tzt
Qca
Tlj
Qpo
?
32
Tza 2
Tza 2
Qpo?
Qpy
Qao
QTsf
Qay2
Qary2
Tsfl?
Qah
Qay2
Qao
Tzs
Tsfl?
CORRELATION OF MAP UNITS
33°52'30"N
?
Tzr
Qay2
DESCRIPTION OF MAP UNITS
107°00'00"W
314000
313000
?
Qay
Tccl
A
27
Tir
Tccu
Qay1a
Tccu
35
312000
02'30"
310000
309000
?
Tccl
3750000
308000
?
33°52'30"N
50'00"
307000
306000
?
305000
304000
?
107°07'30"W
Twl
No vertical exaggeration
2,000
meters ASL
1,800
1,600
1,400
1,200