Qdf
Qajy
Qajy
Qesd
Qaec
3889000
Qes
Qaec
Qesd
Qesd
Qdf
Qay
Qah
Qaec
Qdf
Qazo
Qdf
Qdf
Qls
3888000
Qls
Qafo
Qafo
Qajo
14
Qbc
Qsw
Qafh
af
11 Kdc
Kdou
Qafo
af
Qafo
3888000
Qls
Ttbp
Qajo
1
Kdp
Qes
Kmw
Qajy
Qbg
Qajhf
Qbc
Qbc
Qes
Kdc
77
Kdol
Qafo
Qajo
Qajy
Qajhf
Qajo
Qajh
Qafy
3887000
Note: Soil descriptions after Birkeland (1999), colors after Munsell Color (1994), and all proportions are visual estimates.
Qajh
Qafh
Qajhf
Qbc
Qls
Qbc
L94
35°05.16’N
107°46.52’W
DP04
34°55.97’N
C
L94
35°00.32’N
107°50.45’W Weighted mean of 0 mm/kyr and 5 mm/kyr erosion rate
assumptions
108°04.35’W
3
He
L94
34°59.64’N
108°05.22’W
3
36
He
Cl
L94
DP04
34°59.57’N
34°59.55’N
7
14
33
50
3.0
Ar/Ar
Ar/Ar
K-Ar
K-Ar
36
Cl
M94
LWup
CL88
L93
35°07.52’N
DP04 35°04.49’N
108°05.48’W
108°05.30’W Weighted mean of 0 mm/kyr and 5 mm/kyr erosion rate
assumptions
Inconsistent age, possibly from excess argon
Uncertain age, possibly suffers from excess argon
115-120
--
PM
C97
3238
85
K-Ar
L93
35°05.17’N
Anthropogenic Deposits
Qafh
Qls
Kdp
3886000
Qbc
af
Kmw
Qbm
Qbc
Jm
3886000
af
Kdol
4
05'00"
Qay
Qbc
Qbg
5
af
Qajh
3
Qes
Qay
Qdf
3885000
8
Qafo
Qbc
Qbc
Qbm
Qes
Qdf
Qdf
Jt
Js
Qafy
Qbc
Qdf
Qafo
3884000
Qbg
Js
Qbc
Kdol
Qc
Qes
Qbm
Qbc
Qes
Qesd
Qafy
Qdf
3883000
Jm
Kdou
Qc
Kdol
Jb
Jm
af
4 Kdol
Kdou
Qay
af
af
Qpy
^c
Qpy3
Psa
af
Qdf
Qpo
Qbm
Qbc
^m
Psa
Qpo
Qesd
Qes/Qbc
Qdf
Qbc
Kdp
Qafo
Qbg
Kmc
Jb
1
Kdol
64
Kmc
Qls
Jb
Qafo
Qaf
Qls
2
Qes
Qafo
Qbc
1
Qls
Qae
Qesd
Qes
Qdf
Kdc
Kmw
Qae
Kdp
Qay
Jb
Kdol
Qls
Qls
Qae
?
Qbc
Qbc
Qls
Kmc
Kmc
Kdc
Kdp
Kmc
Kdp
Qls
Qay
Qay
4
Kdt
Kdc
Qaec
4
Qbb
Kdp
Qafy
Qes/Qbc
Kdc
Qbh
Qes/Qbc
Jb
3879000
af
Qes
Qafo
Kdt
Qbc
Qbc
Qes/Qbh
Qae
Qbc
Qesd
Qbm
Kmc
Qbb
Kdp
Qafo
Qes/Qbc
Kdol
Qbc
3878000
Kdc
Kmc
Qay
Qbh
Qafy
Qay
Qay
35°00'00"N
107°52'30"W
238000
240000
239000
241000
242000
50'00"
Kmw
Kdt
Tib
Kdol
Qae
Qesd
3
Kdp
Kdp
Kmc
243000
Kmw
Kmc
Kdp
Qesd
Qes
Kdt
Kdt
Qae
3877000
Qpo
Kmrd
Kdp
Qls
Qes
Qae
Qae
245000 47'30"
244000
Kmw
Kmrd
Qbm
Qae
247000
246000
35°00'00"N
248000
107°45'00"W
Qbb
MAP SYMBOLS
1:24,000
Base map from U.S. Geological Survey 2010.
North American Datum of 1983 (NAD83) World Geodetic System of 1984 (WGS84).
Reprojected to NAD27, UTM Zone 13S.
Projection and 1000-meter grid: Universal Transverse Mercator, Zone 13S
10 000-foot ticks: New Mexico Coordinate System of 1983(west zone), shown in blue.
1
0.5
0
1 MILE
A
A'
!
Roads...........................................................................©2006-2010 Tele Atlas
Names.............................................................................................GNIS, 2008
Hydrography............................................National Hydrography Dataset, 2005
Contours........................................................National Elevation Dataset, 2000
!
MN
1000
0
1000
2000
3000
4000
5000
6000
7000 FEET
73 71
!
1
0.5
0
!
!
1 KILOMETER
CONTOUR INTERVAL 20 FEET
MILAN
SAN
RAFAEL
GRANTS SE
NEW MEXICO
MCCARTYS
Magnetic Declination
August, 2012
9.57498º East
At Map Center
New Mexico Bureau of Geology and Mineral Resources
Open-file Geologic Map 241
Tib
ARROSA
RANCH
LOS
PILARES
CROW
POINT
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).
!
!
?
!
!
!
?
!
Qbh
Geologic contact. Solid where exposed or known, dashed
where approximately known, dotted where concealed; queried
where uncertain.
Qbc
Normal fault, ball-and-bar on downthrown side, shear arrows
show strike slip movement where interpretation suggests.
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.
Anticlinal bend of a monocline, Solid where exposed, dashed
where approximately known, dotted where concealed, queried
where existence uncertain.
[575] 835-5490
This and other STATEMAP quadrangles are available
for free download in both PDF and ArcGIS formats at:
June, 2013
http://geoinfo.nmt.edu
by
Colin T. Cikoski
New Mexico Bureau of Geology and Mineral Resources, 801 Leroy Place, Socorro, NM 87801
Mancos Shale, Clay Mesa Tongue — Black to brown claystone to siltstone. Brown color of 10YR 5/4 measured; brown
color may be an iron oxide stain. 18-24 m thick.
Kdc
Dakota Sandstone, Cubero Tongue — Pale brown to light yellow variably silty fine sandstone. Thinly bedded, particularly
where not bioturbated (30-50 cm thick where massive, 2-12 cm thick where cross-bedded). Vertical and subhorizontal
burrows common. Unit includes a ~2 m thick medial section of mudstone, separating two sandstone intervals. 9-12 m thick.
Younger alluvium of the Zuni Mountains piedmont, undivided (upper Pleistocene to Holocene) — Combined unit of
Qpy1, Qpy2, and Qpy3 of Timmons and Cikoski (2012), mapped where finer subdivision is not readily possible at this scale.
Likely up to 3 m thick.
Qbg
Kmm
Kcs
Kcdi
Kgc
Kge
Km
Kmrd
Kmw
Kdp
Kmc
Kd
Kdc
Kdou
Kdol
Jm
Jb
Js
Jt
Je
201
252
^u
323
^c
^m
Psa
Pg
Py
Pa
*u
major unconformity
541
2500
Xu
Pg
Glorieta Sandstone — Cross section only. 40-45 m thick.
Py
Yeso Formation — Cross section only. 380-385 m thick.
Pa
Abo Formation — Cross section only. 285-290 m thick.
Pennsylvanian Rocks
Pennsylvanian rocks, undivided — Cross section only. Only locally present in the Zuni Mountains, ~150 m thick in the
Gottlieb #1 lithologic log.
*u
Proterozoic Eonothem
Proterozoic rocks, undivided — Cross section only.
Xu
References
Birkeland, P. W., 1999, Soils and geomorphology: Oxford University Press, New York, 430 p.
Cascadden, T. E., Geissman, J. W., Kudo, A. M., and Laughlin, A. W., 1997, El Calderon cinder cone and associated basalt
flows: in: Maberry, K., ed., Natural history of El Malpais National Monument, New Mexico Bureau of Geology and
Mineral Resources, Bulletin 156, p. 41-51.
Champion, D. E., and Lanphere, M. A., 1988, Evidence for a new geomagnetic reversal from lava flows in Idaho – discussion
of short polarity reversals in the Bruhnes and late Matuyama polarity chrons: Journal of Geophysical Research, v. 93,
p. 11,667-11,680.
Dunbar, N. W., and Phillips, F. M. 2004. Cosmogenic 36Cl ages of lava flows in the Zuni-Bandera volcanic field, northcentral New Mexico, USA: in: Cather, S. M., McIntosh, W. C., and Kelley, 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. 309-317.
Kelly, T. E., and Reynolds, C. B., 1989, Structural geology of the Malpais Valley, San Rafael, New Mexico: in: Anderson, O. J.,
Lucas, S. G., Love, D. W., and Cather, S. M., eds., Southeastern Colorado Plateau, N.M. Geological Society, Guidebook
40, p. 119-121.
Laughlin, A. W., and WoldeGabriel, G., 1997, Dating the Zuni-Bandera volcanic field: in: Maberry, K., ed., Natural history
of El Malpais National Monument, New Mexico Bureau of Geology and Mineral Resources, Bulletin 156, p. 25-29.
Laughlin, A. W., Perry, F. V., Damon, P. E., Shafiqullah, M., WoldeGabriel, G., McIntosh, W. C., Harrington, C. D., Wells, S.
G., and Drake [Drakos], P. D., 1993, Geochronology of Mount Taylor, Cebollita Mesa, and Zuni-Bandera volcanic
fields, Cibola County, New Mexico: New Mexico Geology, v. 15, p. 81-92.
Laughlin, A. W., Poths, J., Healey, H. A., Reneau, S., and WoldeGabriel, G., 1994, Dating of Quaternary basalts using the
cosmogenic 3He and 14C methods with implications for excess 40Ar: Geology, v. 22, p. 135-138.
Maxwell, C. H., 1986, Geologic map of El Malpais lava field and surrounding areas, Cibola County, New Mexico: U.S.
Geological Survey, Miscellaneous Map I-1595, scale 1:62,500.
McIntosh, W. C., 1994, 40Ar/39Ar geochronology of late Miocene to Pleistocene basalts of the Zuni-Bandera, Red HillQuemado, and Potrillo volcanic fields, New Mexico (abs.): New Mexico Geology, v. 16, p. 60-61.
Summerville Formation — White to pale yellow, very poorly exposed sandstone, mudstone, and limestone conglomerate(?).
One poor exposure suggests the presence of limestone pebble conglomerate channels, with subrounded to rounded, poorly
sorted fine to medium pebbles in a silty fine to coarse sand matrix; given the poor exposure, however, it is possible this
conglomerate is actually a caliche-cemented Quaternary deposit inset upon the Summerville sandstones. Colors of 2.5Y 8/1
to 7/3 measured. 13-16 m thick.
Js
Molenaar, C. M., 1983, Principal reference section and correlation of Gallup Sandstone, northwestern New Mexico: in:
Hook, S. C., ed., Contributions to mid-Cretaceous paleontology and stratigraphy of New Mexico – Part II, New
Mexico Bureau of Geology and Mineral Resources, Circular 185, p. 29-40.
Munsell Color. 1994 edition, Munsell soil color charts: Kollmorgen Corp., Macbeth Division, New Windsor, N.Y.
Thaden, R. E., Merrin, S., and Raup, O. B., 1967, Geologic map of the Grants SE quadrangle, Valencia County, New Mexico:
U.S. Geological Survey, Geologic Quadrangle Map GQ-682, scale 1:24,000.
Todilto Formation — Gypsiferous light to dark gray fine-grained limestone. Typically <5% of fresh faces is visible grains
(locally up to 20%), with <1-2% fine (<1 mm across) circular fossils. Thinly bedded, 0.5 to 10 cm thick. Colors of 2.5Y 6/1 to
7/1 measured. 5-7 m thick.
Jt
Timmons, J. M., and Cikoski, C. T., 2012, Preliminary geologic map of the San Rafael quadrangle, Cibola County, New
Mexico: New Mexico Bureau of Geology and Mineral Resources, Open-file Geologic Map OF-GM-232, scale 1:24,000.
Entrada Sandstone — Pink to light reddish brown silty fine sandstone and siltstone. Grains are moderately to poorly
sorted, very silty with rare medium sand grains. Indistinctly thinly bedded (2-10 cm thick), but well cross-bedded. Color of
2.5YR 7/4 measured. 45-50 m thick.
Je
Zuni Canyon flow (upper Pleistocene) — Dark gray to black, generally phenocryst-poor basalt. Up to 3% phenocrysts of
translucent greenish pyroxene and olivine, both <1/2 mm across, typically anhedral, and variably degraded to translucent
reddish iddingsite(?). Likely 0 to 4 m thick.
White, W. D., 1989, Geohydrologic and environmental indicators of a dewatered wetland: Ojo del Gallo, San Rafael, New
Mexico: in: Anderson, O. J., Lucas, S. G., Love, D. W., and Cather, S. M., eds., Southeastern Colorado Plateau, New
Mexico Geological Society, Guidebook 40, p. 337-345.
Triassic Rocks
El Calderon flow (upper Pleistocene)— Dark gray to black basalt with rare fine phenocrysts. Up to 5% phenocrysts <1/2
mm across of mainly subhedral translucent greenish pyroxene and lesser (up to 1% of rock) anhedral translucent greenish
olivine. Basalt surface is often largely concealed by eolian material and vegetation, with actual basalt cropping out mainly at
breaks in slope, areas of erosion, and areas with relatively high microrelief. Age of eruption uncertain due to a wide spread
in results, from 34 to 130 ka (Table 1). Likely 0 to 7 m thick.
Zeigler, K. E., Cikoski, C. T., Drakos, P. D., and Riesterer, J., 2012, Preliminary geologic map of the Grants quadrangle,
Cibola County, New Mexico: New Mexico Bureau of Geology and Mineral Resources, Open-file Geologic Map OF-224,
scale 1:24,000.
^u
Triassic rocks, undivided — Cross section only. Includes both ^c and^m. 540-550 m thick.
^c
Chinle Formation, undivided — Poorly exposed red mudstone at the top, reddish brown sandstone and pebble conglomerate
at the base; middle of unit is not exposed. Basal contact placed on the first pebble conglomerate.
^m
Moenkopi Formation — Slope-forming red to reddish brown mudstone along the eastern edge of the quadrangle. Poorly
exposed. Less than 5 m thick.
Paleozoic Erathem
Grants flow (upper Pleistocene) — Dark gray to black generally phenocryst-poor basalt underlying and largely concealed
by Qbc. To date, only conclusively distinguished as a separate flow by the paleomagnetic work of Cascadden et al. (1997).
Here, the contact is placed on a well-defined flow break along the Rio San Jose, and an inferred flow break along the
western margin of the El Malpais valley; only the former contact is verified by paleomagnetic work. Rock mass is up to 4%
phenocrysts of pyroxene (up to 1 mm across, subhedral, translucent greenish) and <1-2% olivine (euhedral, <1 mm across,
translucent greenish). Likely 0 to 7 m thick.
Permian Rocks
San Andres Formation — Light to dark gray limestone and dolomite. Exposed only along the eastern margin of the
quadrangle. 75-80 m thick.
Psa
GEOLOGIC CROSS SECTION
Basaltic dike, unit Tib.
4
Strike and dip of inclined bedding.
2
Strike and dip of inclined bedding, remotely determined.
A
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.
El
La Vega
2,000
Qbg?
Qa
Psa
Qbm
Qa
Qa
?
^u
Pg
Py
Psa
Pg
Pa
*u
Py
?
Pa
Jb
Kdou
Jm
Kdol
Jm Qa
Je
Kdou
Kdc
Jm
Jb
Kmc
Kdp
Kdc
Kdol
2,000
Js
Jt
^u
1,500
Psa
Psa
Pg
Py
1,000
Pa
*u
Pa
Pa
*u
Xu
*u
Xu
500 m
Js
Py
Xu
0 MSL
Kdou
Pg
Pa
*u
500
2,300
meters ASL
^u
Pg
Py
1,000
^u
Psa
Py
Pa
*u
fault terminates
in a monocline
Je
Psa
Pg
1,500
Qbc
Kmc Kdp Kdc
Kdc
Kdou
Kdou
Kdol
Jm
Kdol
Jb Js
Jt
Je
Jt
Je
East
^u
Psa
Py
Qbc
Qbc
Qa
^u
Pg
Bend in
section
S87W N90E
Malpais
A'
Las Ventanas
Ridge
West
Horizontal bedding.
Tib
Kdt
Bluff Sandstone — Light gray to strong olive colored, strongly cross-bedded, dominantly eolian sandstone with local
fluvial sandstone. Variably silty fine to medium sands, mainly of quartz. Thin to medium beds (up to 1.5 m thick observed),
tabular and wedge-shaped, with steep, large-scale, eolian cross-laminae. Local fluvial beds are thinner, up to 20 cm thick,
with low-angle, small-scale cross-laminae. Colors of 5Y 8/2 and 2.5Y 6/6 measured. Forms bold cliffs. 85-90 m thick.
Jb
Hoya de Cibola flow (upper Pleistocene) — Basalt flows burying Qbc, and buried by Qbm and Qbb, locally concealed by
eolian material and vegetation though typically only partially concealed. Likely 0 to 5 m thick.
Qafo Qazo Qpo
Kmg1
Morrison Formation, undivided — Interbedded pale yellow to light brown sandstone, varicolored mudstone, and lesser
conglomerate. Lower sandstones are of silty fine sand, typically pale yellow in color (2.5Y 8/3 measured), and are indistinctly
bedded with cross-laminae. Upper sandstones and conglomerates are pale brown to white, of quartz-rich silty fine to coarse
sand, generally in thin beds (5-8 cm thick) with common, well-expressed cross-laminae. Pebbles, only observed in the
upper part of the unit, are up to 1 cm across, moderately sorted, subrounded to rounded, and mainly of siliceous material
with rare granites (up to 2% of beds) and sparse white to gray quartzites (<<1%). Mudstones are clay to silt, with colors of
5YR 5/3, 5GY 8/1, and 5Y 8/2 measured. Use of Jm here differs from the previous maps of Thaden et al. (1967) and Maxwell
(1986) in that the strongly cross-bedded sandstones and conglomerates between the varicolored mudstones and bioturbated
lower Dakota sandstones are included in the Morrison and not considered a part of the Oak Canyon Member of the Dakota.
Pinches out to the south. 0-30 m thick.
Jm
Bandera flow alluvium (lower Holocene) — Lithologically similar to Qbm, though with more fine-grained eolian cover.
Consistent age estimates range from 9.17 to 12.5 ka (Table 1). Likely 0 to 6 m thick.
Qc
Kgf
Jurassic Rocks
McCartys flow (Holocene) — Dark gray basalt flow largely unconcealed by eolian material or vegetation. Variably
porphyritic, from <1% to 20% phenocrysts, principally of subhedral, <1 mm across pyroxene, but also rare (<3%) plagioclase
as subhedral, clear, <1 mm across prismatic crystals. Age estimates range from 2.4 to 3.9 ka (Table 1). Likely 0 to 6 m thick.
Qbc
Kmg2
Dakota Sandstone, lower Oak Canyon Member — Pale brown to white, variably silty fine to medium sandstone and lesser
pebbly sandstone and siltstone. Thin beds (1-10 cm thick beds) that are typically more massive at the base and internally
planar and cross-laminated toward the top. Vertical and subhorizontal burrows are common. Locally carbonaceous. Pebbles
at the base are up to ½ cm across, poorly sorted, generally well rounded, and principally of light to medium brown siliceous
material with rare quartzite and sparse granite. 8-10 m thick.
Kdol
Older alluvium of the Zuni Mountains piedmont (upper Pleistocene) — Pale to medium reddish brown pebbles to
boulders and silty sands with strong soil development. Stage III carbonate horizon morphology common in outcrop. Colors
of 5YR 5/4 to 8.5/2 measured, with color controlled by abundance of carbonate. Likely up to 10 m or more thick.
Qsw Qls
Kg
Dakota Sandstone, upper Oak Canyon Member — Black to pale brown gypsiferous claystone to siltstone. Strongly
laminated mudstone, commonly wavy, up to 4 mm thick. Local very fine sandstone beds up to 3 cm thick. Colors of 2.5Y
5/3, 7/2, and black (value <2.5, chroma ~1) measured. Unit includes a ~2 m thick sandstone interval dividing two mudstone
intervals. 26-30 m thick.
Older alluvial fan material from Zuni Canyon (Pleistocene) — Gravel, sand, and silt bearing clasts indicative of derivation
from the Zuni Mountain interior, specifically fine pebbles of granite, red siltstone, quartz sandstone, siliceous material, and
arkosic sandstone. Distribution suggests transport from Zuni Canyon into the El Malpais valley prior to the eruption of Qbz
but probably after eruption of Qbc. Thickness unknown, possibly tens of meters in the El Malpais graben.
2,300
meters ASL
Geologic map of the Grants SE quadrangle,
Cibola County, New Mexico
Kmc
Younger alluvium of the El Malpais valley (upper Pleistocene to Holocene) — Fine sand and mud with local fine pebbles,
mainly along shallow, low gradient drainages. Active soils and buried soils are typically weak, A/Bw to A/Bt/Bk (Stage I),
with clay as fine films on ped faces and bridging grains. Likely up to 2 m thick.
Youngest alluvium of the Zuni Mountains piedmont (Holocene) — Brown silty fine to coarse sand with little soil
development. Contains sparse very fine carbonate nodules (Stage I carbonate horizon morphology). Colors of 5YR 6/4 to
7.5YR 5/3 measured. 0-1 m thick.
Qbh
Qbg
Dakota Sandstone, Paguate Tongue — Light yellow to pale brown, variably silty fine to medium sandstone. A massive
base grades up into a bedded but internally massive middle, followed by a bedded and internally cross-stratified top. Beds
are 4-20 cm thick, cross-strata 1-12 mm thick. Unit tends to coarsen upsection, from silty very fine to clean fine-medium
sandstone. Colors of 2.5Y 7/3-8/3 measured on fresh faces. 9-12 m thick.
Kdou
Calcareous alluvium and eolian material (upper Pleistocene to Holocene) — Fossiliferous sand, mud, and sparse fine
pebbles with rare dark gray organic material accumulations. Soil analyzes by White (1989) indicate deposits are up to 100%
carbonate. Fossils are mollusk shells, and carbonate casts of grasses and roots are also locally common. Likely up to 3 m
thick.
Qajo
Synclinal bend of a monocline, Solid where exposed, dashed
where approximately known, dotted where concealed, queried
where existence uncertain.
QUADRANGLE LOCATION
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, New Mexico
87801-4796
Qbz
Location of geologic cross section.
Exposed monocline, showing direction of plunge.
NATIONAL GEODETIC VERTICAL DATUM OF 1929
LOBO
SPRINGS
GRANTS
Kmw
Mancos Shale, Whitewater Arroyo Tongue — Light gray to dark gray siltstone to claystone. Generally very poorly exposed.
Color of 2.5Y 7/2 measured. 4-6 m thick
Quaternary and Tertiary Lava Flows and Intrusive Rocks
Kdt
Kmw
Kmw
Kdp
3
Kdol
Jb
Qae
Kdt
Kmw
Jb
Qbm
Qes
Qbc
Qes
Qbc
Qpy
Qpy3
Kdt
Kdp

Qafy
Qes
Qbc
Qbh
Qae
Qes
Kmw
Jb Kdou
3877000
Kmw
Qesd
af
Qesd
Kdc
Kdol
Qbc
Qes
Qbh
Qls

Qae
Qafo
Qbc
Kdt
Kdp
af
Qes/Qbc
Kmw
Dakota Sandstone, Two Wells Tongue — Light yellow to white, quartz-rich, variably silty fine sandstone and local siltstone.
Typically more massive and thicker bedded base, and more cross-bedded and thinner bedded top. Beds from 1 m thick at
base to 25-40 cm thick at top. Color of 2.5Y 7/4 measured on a fresh face. Gradational basal contact. 9-11 m thick.
Alluvium of the Zuni Mountains piedmont, undivided. Typically subdivided based on age inferred from geomorphology
and soil development. Units are extended from work to the west by Timmons and Cikoski (2012).
Qes
Qaf
Qaf
Qes/Qbc
Qbc
Qbb
3878000
Kdc
Qae
Jb
Qes
Qbc
Qay
Kdp
Kmc
Qafy
Older alluvial fan material from Mezosoic-cored highlands (upper Pleistocene) — Alluvium underlying fan surfaces
inset upon by those of Qafy and bearing buried soils and evidence of a strong active soil. Buried soils have Bt and up to
Stage II Bk horizons and colors of 10YR 6/3-6/4 and 2.5Y 7/4. Evidence for a Stage III K horizon at the top of these deposits,
but this was not observed in outcrop. Likely up to 10 m thick.
Quaternary Piedmont Alluvial Deposits
Zuni Mountains
Kmc
Kdp
Qafo
Qbc
Qes
Qaf
5
af
Qbc
Kdou
Tib
Kmw
Kdou
Qbc
Kdt
Kmw
4
Kmc

Qay
4
Kdp
Qes/Qbc
Qdf
Kmc
Kmc
Tib
Kdp
Kmw
Qazo
6
16

Qes
Qbc
Qdf
Qae
Qes
Kmc
Kdp
Kmc
Qay
Qbc
Qdf
Qbc
3879000
Kdt
Kdp
El Malpais valley alluvium
Kdc
Kmc
Kmc
Kdp
Qls
Kmw
5
Kmc
2
Qls
Kmc
Kdp
Kdol
Younger alluvial fan material from Mezosoic-cored highlands (upper Pleistocene to Holocene) — Alluvium underlying
fan surfaces inset upon those of Qafo and bearing weak soils (A/Bw at most), with colors of 10YR 6/3 measured. Likely up
to 6 m thick.
3880000
4
Kdc
Qafy
Qafo
Qaf
Kmc
Qdf
Kdc
Qay
Kdc
11
13
Qay
Tib
Kdc
Kdou
Qaf
Youngest alluvial fan material from Mesozoic-cored highlands (middle to upper Holocene) — Likely up to 1 m thick.
Qbz
major unconformity
Dakota Sandstone
(including associated tongues of the Mancos Shale)
Alluvial fan material from Mezosoic-cored highlands, undivided (upper Pleistocene to Holocene) — Pebbly sand and
silt derived from small drainages in the flanks of Las Ventanas Ridge and Horace Mesa. Typically subdivided based on age
inferred from geomorphology and soil development.
Qbb
Qesd Qdf
Ttbp
145
Mancos Shale, equivalent to the Rio Salado and D-Cross Tongues — Light gray to medium gray to pale brownish gray,
well-laminated gypsiferous siltstone to claystone and rare sparry gypsum beds. Thinly bedded, with beds up to 6 cm thick,
commonly internally laminated, with laminae <1 to 1 mm thick. 45-55 m thick.
Kmrd
Older alluvium associated with the Rio San Jose (upper Pleistocene) — Thin deposits of sand and gravel associated with
the Rio San Jose at relatively high elevations along the active channel. Largely only identifiable by the presence of sparse
granitic and siliceous pebbles that do not occur in underlying strata. No signs of soil development observed. 0-1 m thick.
Qafh
Kdc
2
Qls
Qls
Qaf
Qafo
Kdou
Kdou
Kdc
1
af
Qafo
3881000
02'30"
Kdou
Qaf
Kdou
Kdc
Kmc
Kmc
Kmc
Kdt
Kmc
Qaec Qae Qes
Gallup Sandstone tongue “F” — Pale brown to pale yellow to gray quartz-rich silty fine sandstone and fine sandy siltstone.
Thinly bedded (4-30 cm thick), commonly massive with burrows at the base, grading up into cross-laminated (1-4 mm thick
laminae). Colors of 2.5Y 7/1-8/3 measured. Designation as unit “F” after Molenaar (1983), previously referred to as “Gallup,
lower tongue” by Thaden et al. (1967) and Zeigler et al. (2012). 12-15 m thick.
Kgf
Younger alluvium associated with the Rio San Jose (upper Pleistocene to Holocene) — Alluvium underlying terrace
treads up to 2 m above the active channel, with typical soil development including a weak reddened Bw horizon and up to
Stage I Bk development. Colors of 10YR 5/4 to 5/6, 7.5YR 5/3 to 5/4, and locally 5YR 4/4 and 7/4, measured. Likely not more
than 3 m thick.
Qbm
Lower tongue of Mancos Shale intercalated with the Gallup Sandstone — Poorly exposed, thinly laminated mudstone
and siltstone located stratigraphically between Kgf and Kge. 10-15 m thick.
Las Ventanas Ridge and Horace Mesa alluvium
Kdc
Qls
Qaf
2
Kdc
Qbm
Qls
Qaf
Kdou
Kdou
Kdou
Qay
Qbg
1
Kdol
8
7
Kdol
Kdol
Qae
63
Kdou
Kdc
Kdp
af
Kdou
Kdol
Qay
Qajy
Kdou
Kdc
Kdol
83
Kdc
Kmc
Qbb
Qes
Qajhf
Qajy
Qay Qpy
Kc
Upper tongue of Mancos Shale intercalated with the Gallup Sandstone — Poorly exposed, thinly laminated mudstone
and siltstone located stratigraphically between Kge and Kgc. 30-36 m thick.
Gallup Sandstone tongue “E” — Pale brown to light yellowish brown, quartz-rich silty-clayey fine sandstone. Thinly
bedded (3-50 cm thick), massive with vertical tubular burrows to well cross-laminated, with 1-3 mm thick laminae. Color
of 2.5Y 8/4 measured for a fresh face. Unit is capped by a distinctive brown, well indurated, calcite-cemented, muddy fine
sandstone, with colors of 10YR 5/4 to 6/3. Designation as unit “E” after Molenaar (1983), previously referred to as “Gallup,
upper tongue” by Thaden et al. (1967) and Zeigler et al. (2012). 15-25 m thick.
Qajh Qajhf
Qpy3
Metamorphic
rocks
major unconformity
299
Gallup Sandstone tongue “C” — Pale brown to light yellowish gray quartz-rich silty fine sandstone. Thinly bedded (5-30
cm thick) with common internal cross-laminae 1 mm to 1 cm thick. Color of 10YR 8/4 measured for a fresh face. Designation
as unit “C” after Molenaar (1983), previously referred to as “Gallup, main body” by Thaden et al. (1967) and Zeigler et al.
(2012). 12-20 m thick.
Kgc
Historic fan alluvium with the Rio San Jose floodplain (Holocene) — Historic alluvium associated with thin alluvial fans
from the termini of gullies and channels along the Rio San Jose floodplain. Likely up to 1 m thick.
Kdou
af
Jb
Kdol
Kdou
2
Qafo
Qpo
Qbc
66
Kdou
63
86
Qes/Qbc
Qpy
Kmc
Qls
62
Kdol
Qafy
Qpy
3880000
Alluvial and eolian sand, undivided (upper Pleistocene to Holocene) — Silty sand and sandy silt transported by wind,
slopewash, and confined water flow. Variably vegetated, typically does not exhibit signs of soil development. <1/2 to 2 m
thick.
Kgm1
Qajo
Kdc
Qls
Kdol
Kmc
Qafo
Qbg
Qbc
Kdou
A'
Kdol
af
Kdol
Kdp
Kdc Kdou
Qafo
79
Kdc
Kdou
63
02'30"
Qpy3
4
Kdou
Kdp
Qafo
3881000
Gallup Sandstone
(including associated tongues of the Mancos Shale)
Qes/Qbc
Qbc
Qbg
Kdou
4
Kmc
Dune sand (upper Pleistocene to Holocene) — Clean to silty fine sand and fine sandy silt forming dune forms of variable
development and sandsheets with mounded microrelief. Variably vegetated, with the more vegetated dunes displaying
weak soil development such as Stage I gypsum accumulation. As much as 5 m thick.
Historic alluvium associated with the Rio San Jose, undivided (Holocene) — Sand and silt with lesser gravel and rare
clays found along the current floodplain of the Rio San Jose. No sign of soil development. Deposits are typically poorly to
moderately sorted angular to rounded silt/sand grains and fine pebbles. Likely up to 1 m thick.
Qaf
Qaf
Kdc
Kdc
Qafo
Qay
af
Qls
71
Kdol
62
2
Qafy
Eolian sand overlying basalt (upper Pleistocene to Holocene) — Hybrid unit that locates areas of either the Hoya de
Cibola (Qbc) or El Calderon (Qbh) basalt flows largely buried by thin (0-1 m thick) eolian sand cover.
Qafh
Qafy
Igneous rocks
Kcda
100
Dilco Coal Member — Heterolithic unit of interbedded pale brown to gray siltstone, pale brown to tan sandstone, and
black coal. Thin bedding to thick laminae; sandstone beds are typically 5-25 cm thick and massive or internally crosslaminated with 1-4 mm thick laminae, while mudstone beds are 3 mm to 3 cm thick, and coal beds are up to 1 cm thick and
discontinuous. Sandstone color of 2.5Y 8/4 measured on a fresh face. 35-45 m thick.
Kcdi
Qajh
af
Qaf
Kdc
73
Jb
Qafo
Qdf
Qdf
Qpo
2
Kdou
Qafo
Qay
Qdf
Kdou
3
4
Kdol
Je
Qbc
^m
^c
Jm
Qdf
Qpo
Qpy
Qafo
Qes
Qbc
Quaternary eolian sand (upper Pleistocene to Holocene) — Silty fine sand and fine sandy silt forming sand sheets and
low dunes. Pale brown colors typical, with colors of 7.5YR 7/3 to 7/6 and N 9 measured. Little evidence of soil development.
Likely up to 2 m thick.
af
66.0
“Stray” Sandstone Member — Pale brown quartz-rich clean fine sandstone. Thinly bedded, 10-40 cm thick, and massive to
weakly internally cross-stratified. Colors of 2.5Y 8/3 to 7/4 measured on fresh surfaces. Includes a 2-3 m thick shale interval,
as well as local mudstone interbeds (<5% of exposures). 20-25 m thick.
Kcs
Rio San Jose alluvium
Qaf
Qae
Kdc
5.3
Kmm
Kge
Qafo
Qdf
Qpy3
Kdol
Qls
Kdc
Kdou
Qbc
Qpy
Qafh
2.59
Mulatto Tongue of the Mancos Shale— Yellowish brown mudstone, mostly siltstone. Strongly planar laminated/bedded
mudstone, with wavy beds 2 to 30 mm thick. Colors of 2.5Y 7/4 to 8/3 measured for fresh surfaces, 10YR 7/6 measured for
weathered surface. Includes a thin quartz-rich very fine sandstone interval. 50-60 m thick.
Historic alluvium, undivided (Holocene) — Boulders to fine sand along active stream channels exhibiting evidence of
historic transport. Deposits are typically poorly to moderately sorted angular to rounded silt/sand grains and fine pebbles.
Likely up to 1 m thick.
Qah
Qay
af
Kdol
3883000
Qafh
Qbc
Jm
Qafo
Qafo
Qbc
1.806
Dalton Sandstone Member — White to pale brown quartz-rich, variably silty fine to medium sandstone. Thin bedding,
typically 10-60 cm thick, with common 1-5 mm thick cross-laminae. Colors of 2.5Y 8.5/1 and 2.5Y 7/2 measured for fresh
faces. 34-40 m thick.
Quaternary Alluvial Deposits
Qaf
Kdc
Qesd Kdc
Qls
Kdol
Qls
Kdol
Kdou
Jm
Jb
Qay
Qaf
0.781
Kcda
Kgm2
Jb
Qafo
Jt
Jb
3
Jt
Qesd
Jm
Kdc
10
Qls
Jm
Jb
Js
Qdf
Kdou
Qae
Js
Qdf
3884000
Kdou
Kdou
Kdol
Js
Qafo
Kdol
Kdc
0.126
Qes/Qbh
Kdol
Qafo
Jt
Qls
Jm
Qafo
Jt
Qls
Landslides (upper Pleistocene to Holocene) — Slumps, slides, debris-flow deposits, and associated fine-grained material
underlying hummocky terrain along slopes below basalt-capped mesas.
Qes/Qbc
Qbc
Qafo
Jb
Colluvium (upper Pleistocene to Holocene) — Gravel, sand, and silt transported by mass wasting and sheet flow. Likely
up to 2 m thick.
Qafh
af
5
3
Qc
Qajh
Qay
Je
Qay
af
Qae
Jm
Je
Deflationary pits (upper Pleistocene to Holocene) — Gray to brown (7.5YR 7/2 and 5YR 4/2 measured), generally welllaminated silt and lesser clay with 5-15% fine sand, subangular to subrounded, accumulating in depressions. Likely up to
2 m thick.
Qes
Qay
Crevasse Canyon Formation
(including associated tongue of the Mancos Shale)
Qdf
Qbm
Je
Qdf
Qbc
Kdol
Jb
Qafo
Qbc
Qafh
4
Quaternary Colluvium, Slopewash, and Eolian Deposits
Slopewash (Holocene) — Sandy silt and silty sand accumulating in depressions in landslide areas. Likely up to 2 m thick.
3885000
Kmw
Qafy
4
Qafo
Qbc
A
Qajo
0.012
107°20.55’W
107°45.29’W Weighted mean of 0 mm/kyr and 5 mm/kyr erosion rate
assumptions
Suggested to have erupted during the Blake
geomagnetic polarity event
107°42.50’W Lower lava flow from southeastern tip of Horace Mesa
Late Cretaceous Rocks
Qsw
Kdt
Qls
Qay
Kdou
Kdc
Qay
Kdp
Qbm
Qae
05'00"
Qes
Kdou
Jm
Qbm
Qajo
Qbc
Kdol
78
88 17
Holocene
Artificial fill — Artificial fill. Compacted gravel, sand, and mud underlying roads, railroads, and water tanks. Up to 5 m
thick.
Qafy
Qbc
Qes
3882000
Qbm
0
Mesozoic Erathem
af
Qdf
Sediments and Sedimentary Rocks
(not to scale)
Intrusive basalt (Pliocene) — Dark gray to dark brownish gray and black pyroxene-plagioclase basaltic porphyry dikes.
Rock mass is up to 10% greenish-translucent subhedral pyroxene, 1-3% clear to white subhedral plagioclase, and sparse
reddish translucent crystals, possibly iddingsite replacing olivine. All phenocrysts <1 mm across. Dikes are 0 to 1 m wide.
Tid
Cenozoic Erathem
Qbc
Longitude
Comments
107°50.33’W
Porphyritic trachybasalt capping Horace Mesa (Pliocene) — Medium gray basalt with up to 5% phenocrysts of mainly
plagioclase (up to 6 mm across, translucent white to chalky white, lathe-like subhedral or fractured anhedral shapes, 2-4%
of rock mass) and pyroxene (<1-6 mm across, black to dark translucent green, anhedral to subhedral, <1-2% of rock mass).
K-Ar age of 3.24 ± 0.09 Ma from Laughlin et al. (1993) thought to be from this flow. 15-25 m thick.
Ttbp
DESCRIPTION OF MAP UNITS
Qajy
Latitude
34°56.01’N
2
Qafy
Qajy
4
3887000
Qafy
af
Kdou
Kdol
Qafo
Qafh
Kdt
Age (Ma)
Ref.4
L94
: Age as published; no attempt made to normalize values. 14C ages are not calibrated calendar ages.
: Uncertainty as published.
3
: PM – age from comparison of radiometric ages and paleomagnetic data to established paleomagnetic sequence; 14C ages date material from buried soils
immediately underlying the flows; 3He and 36Cl are cosmogenic surface exposure ages; 40Ar/39Ar and K-Ar are crystallization ages.
4
: C97 – Cascadden et al., 1997; CL88 – Champion and Lanphere, 1988; DP04 – Dunbar and Phillips, 2004; L93 – Laughlin et al., 1993; L94 – Laughlin et al.,
1994; LWup – Laughlin and WoldeGabriel, unpublished data, cited in Laughlin and WoldeGabriel., 1997; M94 – McIntosh, 1994.
Chief elements of the Grants SE quadrangle. In the background, Horace Mesa is underlain by Pliocene basalt flows capping
Mesozoic rocks from uppermost Chinle Group sediments through the Crevasse Canyon Formation. The hummocky terrain
below Horace Mesa is comprised of landslides. In the foreground, pale yellowish sandstones of the Bluff Sandstone form a
resistant base for the northern end of Las Ventanas Ridge, and are capped by poorly exposed Morrison Formation sediments
and the basal sandstones of the Dakota Formation at the top. The Holocene McCartys lava flow is apparent in the middle
ground left of center. Houses at the base of Horace Mesa lie within the eastern outskirts of the town of Grants.
Qls
Qafy
Kmc
Qesd
41
50
128
54
34.7
Qbh
Qbc
af
Qes
Qdf
14
Qafh
Qbg
Qdf
0.14
0.12
1.1
1.8
1.4
0.6
Qafo
Qbg
Qdf
9.17
9.81
11.0
10.0
12.5
11.2
Qafy
Qajo
Qbg
Qbb
3889000
Qsw
af
Qajo
Qdf
Qaec
4
±2σ 2 Type3
0.12 14C
0.14
3
1.1
He
0.6
36
1.2
Cl
Kdt
Qazo
Qbg
Kge
af
Qajy
Qesd
Qdf
Qazo
Qdf
Kgc
Kmrd
Kdol
Qes
Qesd
3
Qls
Qafo
Qafo
Qbg
Qajh
Qdf
Kmrd
Qafo
Qajy
Qay
Kmg2
Qls
Qafo
Qajy
Qay
Kmg1
Kgf
Unit Age1 (ka)
Qbm 2.97
3.01
2.5
2.4
3.9
Kmw
Qdf
Qdf
Qafy
Kmm
Kcdi
Qafo
8
Qafy
Qbc
Qbg
Qah
Qesd
Qdf
Kmrd
17Kmc
Kdp
Qafh
5
6
Qafo
af
Qes
Kcda
Kcs
Kge
Qajhf
Qay
Qdf
Qay
Qbg
Qls
Jm
Qajy
af
Kmw
4
Kmm
Kdt
Qajh
Qdf
Qaec
Jb
Kgf
Kmrd
Kdt
Kdp
Kmc
21 Kdc
af
Qes
Qay
Qbg
Qes
Qafh
Qes
Qajy
Qbg
Qay
Qaec
Kdol
11
27
Qbg
Qdf
Qafy
Kmg1
Kgf
21 21
28
Jt
af
Kdt
Kmrd
28
Kdou
Js
Qafo
Qes
Qes
Qay
Qesd
Qah
Qah
Qbg
Qdf
Qes
Qazo
Qes
Qes
Qazo
Qajy
Qes
Qafy
af Qes
44
41
Je
Kcdi
Kmg2
CORRELATION OF MAP UNITS
Table 1. Summary of geochronologic data for the Grants SE basalt flows.
3890000
middle upper
Qbg
Qafo
Qajy
af
Qay
Qesd
Qdf
^c
Kge
Qls
Kmw
Qc
Qls Qafo
Kgc
lower
Qbz
Qafh
Qls
35°07'30"N
Ttbp
Kcda
Kcs
Gelasian
Qah
Qesd
Kcdi
Kmg2
Kmg1
Kmrd
Pleistocene
Qay
Qbg
Qesd
Qah
^c
Qafo
Kdp
Kdt
Pliocene
Qajy
Qdf
Je
Qls
Qafy
Quaternary
Qah
Qes
3890000
Qajh
Qes
af
Qaec
Qah
Neogene
Qes
Qesd
af
Late Cretaceous
af
Qajy
107°45'00"W
249000
248000
Jurassic
Qes
af
247000
246000
41 Qc
Jt
Js
34 Kdol
Jm
Qls Jb Qc
Jb
Triassic
Psa
Qpy
47'30"
245000
244000
Permian
243000
Penn.
50'00" 242000
241000
Cenozoic
240000
Mesozoic
239000
Paleozoic
107°52'30"W
35°07'30"N
NMBGMR Open-file Geologic Map 241
Last Modified April 2013
A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
Proterozoic
NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES
?
Xu
500
*u
Xu
Xu
No vertical exaggeration
Subsurface geology beneath the Malpais basalts adapted from Kelly and Reynolds (1989).
Pre-Jurassic unit thicknesses from Maxwell (1986), Timmons and Cikoski (2012), and the Gottlieb #1 core log.
0 MSL