Ql
Kbc
10
Qc
1
Kbc
Kbc
5
Qal
Kbc
Kbc
Qc
Kbc
Qc
5
Qc
Kbc
Qal
8
353000
352000
2
6
Qc 7
Kd
14
17
Qc
Kd
Qc
6
3
2
Kd
6
Kd
3
Kbc
3
Qal
Kd
Kbc
Jm
4
Jm
Qc
4011000
Qc
Kd
Kd
Js
Jtg
Qls
Jm
Js
Qp2
^cu
Qls
Qls
Qoa
^cu
Qal
Qp3
Qal
^cu
Qp3
Qp3
20
^cpd
Qoa
Jm
^cpd
Qal
9
Qc
^cu
Ql
7
^cm 7
4 ^cp
^cp
^cm 15
Qc
Qes
Qc
Qls
Qoa
^cm
^cm Qal ^cp Qal
Qes
Qes
Qoa
Qls
^cu
Qal
10
^cu
^cm
Qes
^cp
4007000
Qes/Qc
4
2
2
^cp
11
^cl
Qal
3
^cm
8 3
6
^cm
Qls
5
12
Qls
5
15
13 ^cm
2
4005000
^cm
13
^cp
6
^cu
5
^cm 3
11
9
13
2
*Pca
Qt3
22
6
4
3
2
Qal
3
4
6
^cl
^cl
*Pca
4004000
*Pce
^cp
^cl
*Pca
3
^cl
^cp
*Pca
2
Qt3
4004000
Qls
Qrf 2
Qt3
*Pca
^cl
36°10'0"N
Qc
*Pce
*Pce
*Pce
Qc
20
20
^cp
Qt3
4003000
Qes
Qt2
*Pce
Qt3
Qes
Py
2
*Pca
Qt2
Qt3
*Pce
36°10'0"N
Qt2
Qt3
*Pca
^cl
Qls
7
*Pca
Qt
*Pca
20
3
*Pca
Qes
*Pce
*Pce
Qlsy
Qtl
^cl
6
*Pce
Qc
^cl
Py
3
4
7
2
Qc
Qls
4002000
*Pca
Py
Py
Qc
38
^cl
Qc
Py
Qc
13
^cp
56
^cp
8
4
24
42
5
344000
345000
346000
106°45'0"W
347000
Qbt
350000
349000
1
ECHO
AMPHITHEATER
NEW MEXICO
GALLINA
NACIMIENTO
PEAK
Arroyo
ARROYO
del
DEL AGUA
Agua
JAROSA
Qcbt Qbt
0.5
1000
0
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
Qes
Qt n
Qp n
Qc
Qcbt
Qls
Qoa
Qbt
Qbo
QTg
Kd
Kbc
Symbols
Jm
Js
Jt
Contact
Jtg
Jt(ls)
Dashed contct
Je
TRcu
TRcpf
TRcm
65
TRcp
0-30
TRcl
Normal fault
Ball on downthrown side;
arrow shows direction
of dip
Strike and dip
First number is direction of dip
and second number is amount of dip
Py
Flow Foliation
Pca
IPPce
Lawrence
Osburn
Zeigler
Ze
igl
er
of Pipiringos and O’Sullivan (1978) and Lucas (1993). Sandstone beds in the
Shinarump Formation are absent to thin (1 to 2 m) in the Rio Puerco valley, but locally
are as much as 20 m thick. In many places in the Rio Puerco valley, color-mottled shale
of the Shinarump Formation sits directly on altered, weathered Yeso Group or uppermost
Cutler Group; the Shinarump sandstone may be absent or channel sandstone of
Shinarump lithology may be 2 to 4 m above the contact with the Permian rocks.
Kelley
Osburn
Pennsylvanian-Permian
The oldest strata exposed on the Arroyo del Agua quadrangle are PennsylvanianPermian siliciclastic red beds of the Cutler Group (Cutler Formation of Smith et al.,
1961) and overlying Yeso Group. Stratigraphy employed here follows Lucas and Krainer
(2005) and Lucas et al., 2005).
Osburn
0
1
Kilometers
2
3
4
^cl
Py
Qc
Py
*Pca
Qc
^cl
Py
Py
Qal Qcbt
Qcbt
Qbt
^cp
Qbt
^cl
Qbo Py
3999000
36°7'30"N
353000
0
1000
2000
3000
1 MILE
4000
5000
6000
Geologic map of the Arroyo del Agua
quadrangle, Rio Arriba County, New Mexico
7000 FEET
May 2006
1
QUADRANGLE LOCATION
Qbt
352000
351000
YOUNGSVILLE
CERRO
DEL
GRANT
Qal
106°40'0"W
106°42'30"W
1:24,000
LAGUNA
PEAK
^cp
^cu
*Pca
*Pca
Qc
7
15
^cu
Base map from U.S. Geological Survey 1984, from photographs taken 1976, field checked in 1976, edited in 1984.
1927 North American datum, UTM projection -- zone 13N
1000-meter Universal Transverse Mercator grid, zone 13, shown in red
FRENCH
MESA
*Pca
Qc
348000
Qlsy
4000000
Py
Qbo
^cl
28
343000
9
QTg
Py
5
Qrf
8
7
*Pca
Correlation of Map Units for the Arroyo del Agua 7.5-Minute Quadrangle
8
37
13
Triassic
All Triassic strata on the Arroyo del Agua quadrangle are assigned to the Upper Triassic
Chinle Group (Lucas, 1993). Triassic stratigraphy follows Lucas and Hunt (1992) and
Lucas et al. (2003, 2005b).
TRc Chinle Group (Late Triassic). Three informal units are mapped at the 1:24,000
scale, from younger to older:
TRcu an informal upper unit that contains the Rock Point Formation and the
Petrified Forest Formation. (where exposure permits the Petrified Forest Formation is
divided into the Painted Desert Member (TRcpd) and the Mesa Montosa (TRcm)
member). The stratigraphically highest unit in the Chile Group is the Rock Point
Formation, a reddish brown to gray-red siltstone and fine-grained sandstone. The
sandstone can locally be a coarse-grained sandstone or a granule conglomerate. The
thinly interbedded sandstone and siltstone beds form a ribbed cliff where the Rock Point
outcrop is not deeply weathered. Where weathered, the Rock Point Formation is an
orange slope. The Rock Point base is the first persistent bed of sandstone above slopeforming mudstone of the Painted Desert Member of the Petrified Forest Formation. The
top of the Rock Point is a sharp contact with the overlying eolian sandstone of the Slick
Rock Member of the Jurassic Entrada Sandstone. The Rock Point Formation in the
Chama Basin is up to 30 m thick (Lucas et al., 2003). The Petrified Forest Formation,
which is reddish-brown bentonitic mudstone that forms extensive slopes and dissected
badland areas where exposed, consists of two members, the Painted Desert
Member (TRcpf) and the Mesa Montosa (TRcm) member. The overlying Painted Desert
Member is up to 176 m of reddish brown, bentonitic mudstone and thin ledges and lenses
of ripple-laminated or crossbedded sandstone. Its base is a thick mudstone bed above the
highest sandstone ledge of the Mesa Montosa Member. Its top is a sharp contact with
siltstone/sandstone of the Rock Point Formation (locally), or sandstone of the Jurassic
Entrada Sandstone can rest directly on the Painted Desert Member. In the vicinity of
349493 4008607 (NAD27), downward tapering wedges of sandstone that are 0.5 to 1 m
long are present in the mudstone of the Painted Desert Member at the Painted Desert
Member/Entrada contact. We interpret these as sandstone dikes that filled fissures in the
underlying lithified Chinle Group strata when the Entrada Sandstone was deposited on
the J-2 unconformity surface that separates the Chinle and Entrada. The lower, Mesa
Montosa Member is made of up to 24 m of mostly sandstone and lesser amounts of
mudstone and siltstone that range in color from reddish brown to green; the sandstone
beds are typically ripple-laminated to thinly-laminated. The Mesa Montosa Member
forms a ribbed slope, 4 to 24 m thick, between coarser-grained Poleo Formation
sandstone below, and slope-forming mudstone of the Painted Desert Member of the
Petrified Forest Formation above. The Petrified Forest Formation is up to 200 m thick.
TRcp Poleo Formation. Yellow-brown, yellow- gray, white and red, medium
to fine-grained, micaceous, cross-bedded, quartzose sandstone, conglomeratic sandstone
and conglomerate. The conglomerate in the Poleo Formation is is often black and
contains both intrabasinal siltstone and nodular calcrete clasts and extrabasinal siliceous
(chert and quartzite) clasts. This unit forms prominent white cliffs. The base of the unit is
sharp (corresponds to the Tr-4 unconformity of Lucas, 1993) and the upper contact is
gradational into the overlying Mesa Montosa Member of the Petrified Forest Formation.
The Poleo Formation is about 48 m thick
TRcl an informal lower unit that contains the Salitral Formation and the
Shinarump Formation. The Salitral Formation is dominantly green, purple and red
smectitic mudstone with calcrete nodules. The unit tends to be olive gray to reddishbrown silty mudstone near the base (Piedra Lumbre Member) and a maroon to reddishbrown mudstone (Youngsville Member) near the top. An orange chert bed that is 2 to 20
cm thick is common in the Piedra Lumbre Member. A sandstone bed at the top of the
Piedra Lumbre Member, the El Cerrito Bed, is a local yellow to reddish brown
conglomeratic sandstone that is as much as 10 m thick on Mesa Montosa. The base of
the El Cerrito bed marks a profound change in the degree of alteration of the rocks by
paleoweathering during Triassic time. Below the El Cerrito bed, both the Shinarump
Formation and the Piedra Lumbre Member of the Salitral Formation can be mottled;
mottling is rare above the base of the El Cerrito Bed. The Salitral Formation varies
greatly in thickness, ranging from 3 to 30 m. The Shinarump Formation (= Agua Zarca
Formation of previous usage: e.g., Wood and Northrop, 1946; Dubiel, 1989; Lucas and
Hunt, 1992) consists of white, red, orange, and brown quartz sandstone, conglomeritic
sandstone, and extrabasinal conglomerate that includes clasts of quartz, chert, and
quartzite (Lucas et al., 2003) interbedded with or sitting on olive gray to reddish-brown
silty mudstone. Local mineralization (copper, uranium) produces colors that range from
black to yellow to green. Trough crossbeds are the dominant bedform. Petrified wood is
rare. The basal contact is sharp; the basal contact corresponds to the Tr-3 unconformity
Qbo Qbo
11
5
Qc
Qc
A
11
Jurassic
Jurassic stratigraphy on the Arroyo del Agua quadrangle follows Lucas et al. (2005a),
which is based on the regional stratigraphy of Anderson and Lucas (1992, 1994, 1995,
1996, 1997) and Lucas and Anderson (1997, 1998).
Jm
Morrison Formation - Brushy Basin Member. (Late Jurassic).
All Morrison strata on the Arroyo del Agua quadrangle are assigned to the Brushy Basin
Member, which is a variegated pale greenish gray, grayish yellow green, pale olive,
yellowish brown, and pale reddish brown bentonitic mudstone with a few beds of troughcrossbedded pebbly sandstone. Locally, the base of the Morrison Formation is a thin (up
to 8 m thick) interval of trough-crossbedded sandstone and interbedded mudstone. This
basal interval is likely correlative to the Salt Wash Member of the Morrison Formation to
the west and south. However, this interval is neither thick enough, persistent enough, nor
lithologically distinctive enough to separate from the Brushy Basin Member. The upper
part of the Brushy Basin is, in places (e.g., 353408 4011319 to 352908 4010853, NAD
27), dominated by an interval that is ~ 30 m thick composed of white to pale green
sandstone interbedded with green siltstone that may be correlative to the Jackpile
Member of the Morrison Formation in the southern San Juan Basin. The sandstone in the
upper part of the interval is a pale green, thin to medium tabular bedded, medium to very
fine-grained litharenite with well-sorted, subrounded quartz grains. The lower part of the
interval consists of 3 m thick beds of cross-bedded white to red, medium-grained, wellrounded, well-sorted, litharenite that is conglomeratic at the base; the clasts are
intrabasinal siltstone. Total Morrison thickness up to 85 m thick.
Js
Summerville Formation (Middle to Late Jurassic). (includes the Bluff
Sandstone (Late Jurassic), because the Bluff Sandstone is difficult to trace laterally). The
Bluff Sandstone is light gray, very fine grained, well sorted sandstone with crossbeds in
thick sets. Consists of two members not mapped separately. The lower, Junction Creek
Member comprises most of the formation (30-40 m thick) and is mostly pale yellowish
green and light olive gray, very fine grained, well sorted sandstone with crossbeds in
thick sets. These are primarily eolian deposits similar to the type section of the Junction
Creek Member near Durango, Colorado (Goldman and Spencer, 1941). The overlying
Recapture Member is 6 to 14 m thick and is mostly maroon, pale brown, grayish red, and
light greenish gray gypsiferous siltstone, fine-grained sandstone and mudstone. Recapture
strata lithologically resemble underlying Summerville strata. Their fine-grained
gypsiferous lithotypes indicate that these strata do not belong to the Morrison Formation
(contra Ridgely, 1977, 1979), but instead are assigned to the Recapture Member of the
Bluff Sandstone (Lucas and Anderson, 1997, 1998; Lucas et al., 2005). 44 to 47 m thick.
The Summerville Formation below the Bluff interval is thinly and cyclicallybedded, maroon, grayish red and yellowish gray siltstone, sandy siltstone, fine
gypsiferous sandstone and mudstone. In the Chama Basin, the Summerville Formation
(as used by Lucas and Anderson, 1998; Lucas et al., 2005) consists of two,
lithologically-distinct units that Lucas et al. (2005) referred to informally as the lower and
upper members. These two units merit formal recognition because of their distinctiveness
and ready recognition in quadrangle-scale mapping.
As Lucas et al. (2005) noted, the lower member of the Summerville Formation in
the Chama Basin is the same unit that Goldman and Spencer (1946) named the “Bilk
Creek Sandstone Member of the Morrison Formation” in the Telluride-Durango area of
southwestern Colorado. Therefore, we apply Goldman and Spencer’s (1941) name to the
lower member of the Summerville Formation in the Chama Basin. Here, the Bilk Creek
Member of the Summerville Formation is ~ 12-15 m thick and is repetitively-bedded
gyspiferous sandstone, siltstone, and limestone that forms a ribbed cliff or slope. This
yellowish green to light brown unit overlies the Tonque Arroyo Member of the Todilto
Formation and locally appears to interfinger with it. The overlying Mesa Alta Member of
the Summerville Formation (named here) overlies the Bilk Creek Member in the Chama
Basin.
We name the upper member of the Summerville Formation in the Chama Basin the Mesa
Alta Member. The name is for Mesa Alta on the Arroyo del Agua quadrangle where the
type section of the unit is located (sec. 19-20, T23N, R3E). The type section is units 1525 of the Mesa Alta measured section of Lucas et al. (2005, p. 190, fig. 3). At the type
section, the Mesa Alta Member is ~ 96 thick, which appears to be a maximum thickness
in the Chama Basin, where the unit is 61-96 m thick. The type section is interbedded
siltstone, gypsiferous sandstone and mudstone that forms a grayish red- and white-banded
slope between the Bilk Creek Member (below) and the Bluff Sandstone (above).
In the Four Corners, and across much of southeastern Utah, the Summerville
Formation has been divided into two members—the Beclabito (lower) and Tidwell
(upper) members (Lucas and Anderson, 1997). These members, however, are not the
same two Summerville members that are present in the Chama Basin. Thus, the Tidwell
Member is mostly laterally equivalent to the Bluff Sandstone (Lucas and Anderson,
1997), so that the Summerville Formation in the Chama Basin is equivalent to the
Beclabito Member to the northwest. Strata we term Summerville Formation were
assigned to the Morrison Formation by Smith et al. (1961) and Ridgley (1977, 1979),
although Ridgley (1989) did assign what we term the lower member of Summerville
Formation to the Wanakah Formation. 74 to 111 m thick.
Je
Entrada Sandstone (Middle Jurassic). Trough crossbedded and ripplelaminated, cliff-forming sandstone. The Entrada Sandstone (only the Slick Rock Member
is present in the Chama Basin: Lucas et al., 2005a) is 60 to 76 m of very fine- to mediumgrained, moderately well sorted sandstone that forms bold cliffs along escarpments and
mesa tops. Trough crossbeds and ripple laminations are the dominant bedforms. Colors
are shades of yellow, light brown and grayish orange. Up to 76 m thick.
Pca Arroyo del Agua Formation (Early Permian) -- Orange siltstone,
arkosic sandstone and minor intraformational and extraformational conglomerate. The
siltstones are thick, slope-forming units with abundant calcrete nodules between thin
sandstone sheets that are arkosic and trough crossbedded. Up to 130 m thick.
IPPce El Cobre Canyon Formation (Late Pennsylvanian-Early Permian).
Brown siltstone, sandstone and extraformational conglomerate that overlies Proterozoic
basement in the subsurface and is conformably overlain by the Arroyo del Agua
Formation. Siltstone beds of the El Cobre Canyon Formation contain numerous rhizoliths
and comprise relatively thin, slope-forming units between multistoried sandstone beds
that are arkosic, micaceous, coarse grained and trough crossbedded. On the Arroyo del
Agua quadrangle, upper part contains numerous vertebrate fossils, primarily of Early
Permian amphibians and reptiles (e.g., Langston, 1953; Berman, 1993; Lucas et al.,
2005c). Up to 90 m thick.
IPgb- Guadalupe Box Formation. (Late Pennsylvanian). Recently defined by Krainer
et al. (2005) ( =Upper arkosic limestone member of the Madera Group of Northrop and
Wood (1946)). Interbedded red to green micaceous, arkosic sandstone, gray sandy,
arkosic limestone, gray, fossiliferous, sandy arkosic, cross-bedded limestone, and red,
green, and black shale and siltstone. Most common fossils are crinoid columnals. Some
arkosic clasts are up to 2 cm in diameter and are angular. Upper contact gradational with
clastic red beds of the overlying Cutler Group; lower contact not exposed.
^cu
Qc
18
24
4
*Pca
5
^cl
32
7
^cp
*Pca
41
Qls
4
9
7
40
53
30
Qc
6
Qc
45
*Pce
*gb
^cu
Qls
^cp
22
20
Qbo
Qbo
Qbo
Magnetic Declination
February, 2005
10º 7' East
At Map Center
0.5
0
1 KILOMETER
by
Kelley, S.A. , Lawrence, J.R. , Zeigler, K.E. 3, Osburn, G.R. 4, and Lucas, S.G. 5
1
CONTOUR INTERVAL 20 FEET
NATIONAL GEODETIC VERTICAL DATUM OF 1929
2
1
NMBGMR, Socorro, NM, 87801
Lawrence GeoServices Ltd. Co., 2321 Elizabeth Street NE, Albuquerque, NM 87112
3
Department of Earth and Planetary Science, University of New Mexico, Albuquerque, NM 87131
4
Earth and Planetary Science Dept., Washington University, St. Louis, MO 63130
5
New Mexico Museum of Natural History and Science, Albuquerque, NM 87104
2
New Mexico Bureau of Geology and Mineral Resources
Open-file Map Series
Photograph showing paleochannel filled by the Tshirege Member of the Bandelier Tuff
(Qbt) inset against Permian Yeso Group (Py), Shinarump (TRcsh), Salitral (TRcs), and
Poleo (TRcp) formations of the Triassic Chinle Group, and the Otowi Member of the
Bandelier Tuff (Qbo). Southeast side of Ojitos Mesa (channel located at approximately
352600 399100, NAD27), view toward west.
OFGM 124
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
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.
SW
NE
A
fe )
Qal
14
6
Elevat
27
^cl
Py
*Pca
38
Qls
8
^cl
Py
^cl
Quaternary to Tertiary
QTg Fluvial gravel (early Pleistocene to Pliocene). Unconsolidated subround fluvial
gravel is present under the Otowi Member of the Bandelier Tuff on Triassic Chinle
Group strata on Ojitos Mesa. The gravel is composed primarily of clasts of Pedernal
Chert, Pennsylvanian limestone, and Proterozoic granite and quartzite clasts recycled out
of the lower Abiquiu Formation. This gravel, which is up to 2 m thick, may correlate
with the Puyé Formation in the northeastern Jemez Mountains.
Py ^cl
58 23
44
Qbo
38
Py
^cl
Qc
4001000
36°7'30"N
4
4001000
^cp
23
*Pca
^cl
^cl
Qls Qal
5
^cl
4
10
Qc
Qc
Py
20
*Pca
4000000
Qbo
^cm
*Pce
7
4002000
^cm
Kbc Burro Canyon Formation (Early Cretaceous). White, light yellow, orange, and
buff, conglomeratic sandstone with thin lenses of pale green and pink mudstone (Saucier,
1974). Small-scale trough cross-bedding and cut-and-fill structures are associated with
the conglomeratic channels. Petrified wood is locally present in gravels. Conglomerate
clasts are mostly varicolored quartzite and chert pebbles up to 2.5 cm in diameter, with
minor sandstone and limestone clasts. Chert gravel is present fairly uniformly throughout
the unit vertically, in contrast to the Ghost Ranch area, where gravel is rare in the upper
part of the unit. Pebbly conglomerate makes up less than 50% of the unit. Laminar lowangle wedge and high-angle planar wedge cross-bedding is common in the sandier
portions of the formation. The sandstone is fine to medium grained, quartzose, and
kaolinitic. locally containing a minor percentage of quartz and chert granules and
pebbles. 40 to 50 m thick.
IP-PC Cutler Group (Pennsylvanian-Permian)
We assign the oldest siliciclastic red beds in the Chama Basin to the Cutler Group. Lucas
and Krainer (2005) divided Cutler strata into two, mappable lithostratigraphic units, the
El Cobre Canyon and Arroyo del Agua formations. Several lithologic criteria allow the
two formations to be distinguished:
Contrasting features of the El Cobre Canyon and Arroyo del Agua formations.
ence
Lawr
Qb
Bandelier Tuff (early Pleistocene). Pumaceous air-fall tephra, nonwelded to
weakly welded rhyolitic ash-flow tuff, and local volcaniclastic sediments; divided into
two members, from younger to older:
Qbt Tshirege Member. White to orange to pink non-welded to weakly
welded rhyolitic, ash-flow tuff (ignimbrite). The tuff contains abundant phenocrysts of
sanidine and quartz, rare microphenocrysts of black clinopyroxene, trace
microphenocrysts of hypersthene and fayalite, and pumice fragments in a fine-grained
matrix of vitric ash. The sanidine typically displays blue iridescence. The tuff is
composed of multiple flow units in a compound-cooling unit (Smith and Bailey, 1966;
Broxton and Reneau, 1995); includes basal white pumiceous tephra deposits (1-2 m
thick) of the Tsankawi Pumice. Qbt forms conspicuous orange to tan cliffs on Loma
Redonda and along the southern edge of the quadrangle, east of Mesa Ojitos, where the
tuff infills a rugged northeast-trending paleocanyon. 40Ar/39Ar age is 1.22 ± 0.01 Ma
(Izett and Obradovich, 1994; Spell et al., 1996). Up to 75 m thick.
Qbo Otowi Member. White to pale pink, generally poorly welded rhyolitic
ash-flow tuff containing abundant phenocrysts of sanidine and quartz, and sparse mafic
phenocrysts; sanidine may display a blue iridescence. Contains abundant accidental lithic
fragments; consists of multiple flow units in a compound cooling unit. The stratified
pumice fall and surge deposit at base of unit (Guaje Pumice) is not found in this area.
Qbo discontinuously fills in rugged topography on a pre-Toledo caldera age volcanic
surface and the upper surface can be quite undulatory due to erosion. Qbo disontinuously
caps Ojitos Mesa and fills an inset valley along the southeast edge of the quadrangle.
Very difficult to distinguish from upper Bandelier Tuff in hand samples; best
distinguished by poorer degree of welding, greater tendency to form slopes instead of
cliffs, more abundant lithic fragments, less abundant iridescent sanidine, and stratigraphic
position beneath the Tsankawi Pumice. 40Ar/39Ar ages 1.61± 0.01 to 1.62±0.04 Ma (Izett
and Obradovich, 1994; Spell et al., 1996). Up to 65 m thick .
5
Qls
2
1
Qc
Qls
2
10
^cp
4006000
4
^cp
12
3
*Pca
Qal
Qls
4005000
15
2
4
^cm
2
^cl
Qls
10
Qes
^cp
^cp
Qc
3
^cp
^cu
2
7
3
^cl
Qal 4
^cm
3
2
4
4003000
^cp
Qls
^cm
^cp
^cm
10 22 ^cm
36
4007000
9
^cm
3
5
18
2
Qal
3
18
2
Qes/^cu
5
2
4006000
Qes
3
3
A'
29
^cm
Qp
11
^cp
24
Qal
4
^cu
4 Qes
^cm
4
Qal
^cp
Qls
36°12'30"N
4008000
^cp
*Pca
10
2
Qes
8
Qal
^cu
13
Qls
^cl
^cm
^cp
Qes/Qoa
^cp
2
Qc
^cp
Qc
16 15
4
41
10
^cu
^cu ^cm
3 5
^cm
^cm
Qes/Qoa
13
Qe
12 ^cpd
7
Qes/Qoa Qes/Qoa
Qal
^cu
^cl
^cu
8
^cu
Qc
Qes
Qes/Qoa
5 5
^cm
4009000
1 12
Qoa
Qoa
^cu
^cpd
^cp
^cu
Qls
Qal
8
^cp
14
^cp
Qls 10 ^cl
^cpd
*Pca
44 Qls
Qal
Qc
^cp
*Pca
11
^cpd 1 15
Qal
Qal
Qls
10
^cu
Qoa
Qoa
^cm
Qc
Qls
Qoa
Qoa
Qal
Qoa
^cu
Qls
Qal
^cm
Qls
10
^cp
^cpd
Je
^cu
Qc
^cu
Qal
Qls ^cu
Qoa
Qoa
^cm
^cu Qc
Qls
Qls
Js
Je
^cu
Qls
Qoa
4008000
Qls
10
14
Qal
Jtg
Jtg
^cu
Qls
Ql
^cu
^cu
^cu
5 6
Qls
13
Qc
Qc
Ql
^cpd
Qc
8
Jtg
Je
^cpd
Js
Jm
8 Js
^cu Je
16
Qc
Jmb
Qls
Js
Qes
Qes
Jm
Jm
Qoa Qp2
Qc
4009000
11
4010000
Qa Qls
Qls
8
Qp2
^cu
Qls
Js
Qls
2
^cu
Qls
Jm
4
Kd Kd
Jm
Qc
Jm
Jm
Jtg
Qls
Kbc
Jm
Qls
Je
Qc
Qal
Kbc
Js
Qls
^cu ^cu
^cu
Qc
6
Jm
Kbc
Jm
Je
^cu
Je
5
4
2
Jm
4
Jtg
^cu
Qc
36°12'30"N
Jm
Jtg
Js
^cu
Js
3
Jm
Je
Jtg
Qal
Kbc
Jm
Jm
Js
Jtg
Qls
6
Qal
Qal
5
Js
Jm
Qts
Je
Qc
5
4011000
Qc
11
6
Jm
Jm
Qls
Jm
Js
Qls
Jm
Jm
Qc
6
Qc
Kd Kbc
Jm
70
Jtg
Qls
Jm 3
2
Jm
Kd
Js
Kbc
6
Kbc
4
Qc
Kbc
Kbc
Kbc
Jm
Kbc
1
5
Jm
Kd
Qe
14
Jm
Qal
Jm
4
Kd
6
Qc
4012000
6
2
Kbc
Qc
Kbc
2
Kbc
Kbc
Kd
2
Kbc
Kd 4
Qc
7
Kbc
Kbc Kbc
Ql
Kbc
Kbc
Kbc
4010000
Qc
7
14
Qc Kbc
Qal
Kbc
Kbc
5
Kbc
Kbc
Qc
6
Qt
Kbc
Qal
Kd
Qc
Qal
Qc
7
Qal
Kbc
Kbc
Qc
2
Kbc
4
Kbc
Qc
Kbc
5
Qc
Kd
2
4
Kbc
4012000
Jm
Kbc
Qal
H
4
Kbc
Qc
Kd
7
351000
350000
P
2
4
349000
P
Kbc Kbc
Qal
348000
Q
Qal
Qal
347000
Py
Yeso Group (Early Permian). Orange-red medium-grained, moderately to wellsorted sandstone with large-scale (eolian) crossbeds, or more rarely, laminated sand sheet
bedding. These strata are equivalent to the De Chelly Sandstone of the Yeso Group
(Baars, 1962; Krainer et al. 2005) (Meseta Blanca Member of the Yeso Formation of
Northrop and Wood, 1946 ). The eolian sandstone gradationally overlies or is
interbedded with the arkosic fluvial deposits of the Arroyo del Agua Formation and is
overlain with prominent unconformity by basal strata of the Chinle Group. The unit thins
to the northeast; the line of termination for the unit trends northwest. Along the
termination, the Yeso Group sand deposits are discontinuous and range in thickness from
zero to 3 to 5 m, suggesting a facies change to a more fluvial environment toward the
northeast. Up to 20 m thick.
y
346000
Last Modified 05 March 2014
Te
345000
Jt
Todilto Formation (Middle Jurassic). The Todilto Formation consists of a
lower, limestone-dominated interval (Luciano Mesa Member, Jt (ls)) overlain locally by
a gypsum interval (Tonque Arroyo Member; (Jtg) (Lucas et al., 1985, 1995; Kirkland et
al., 1995). The Luciano Mesa Member is 2 to 8 m thick and consists mostly of thinly
laminated, dark gray or yellowish gray, kerogenic limestone. Beds near the base of the
member are usually sandy, and microfolding of the thin limestone laminae is common.
The overlying Tonque Arroyo Member is up to 30 m of white to light gray gypsum
interbedded with carbonate. A thin limestone bed (0.5 to 2.0 m) is deposited on the
gypsum of the Tonque Arroyo Member in many places along the Mesa Alta escarpment..
Total Todilto Formation thickness is up to 38 m.
Three lithologic relationships are associated with the Tonque Arroyo Member in the
Arroyo del Agua area: (1) gypsum interbedded with carbonate is preserved (classic
Tonque Arroyo Member); (2) a limestone microbreccia left by dissolution the gypsum of
the Tonque Arroyo Member is present; or (3) the Tonque Arroyo member is interbedded
with a green to red medium-grained quartz sandstone in two places along the escarpment
(344730 4009647, 347100 4009590). Thus, the Todilto Formation in the vicinity of
Arroyo del Agua contains a record of places where gypsum was deposited and is still
preserved, areas where the gypsum was deposited, but has since dissolved away, and
places where the gypsum is interbedded with clastic shoreline deposits. A chaotic breccia
that contains angular blocks up to 1 m across is often preserved along the contact
between the limestone microbreccia and overlying basal Summerville sandstone. The
breccia can contain blocks of: (1) basal Summerville sandstone only; (2) blocks of
Summerville sandstone and limestone mircrobreccia; or (3) blocks of Summerville
sandstone and the gypsum-capping limestone. The timing of brecciation post-dates the
lithification of both the limestone and the sandstone, as well as the microbreccia-forming
dissolution event.
C
344000
NMBGMR Open-file Map Series OFGM-124
J
106°40'0"W
106°42'30"W
343000
Quaternary
Qrf Rock Fall (Holocene). Building-sized blocks of Poleo Formation that have
broken away from the edge of the sandstone cliff in the recent past (0358913 N 4003825
E, NAD 27); the Ponderosa pine trees affected by the fall are dead, but the wood decay
process is not very advanced.
Qsly Young landslide deposit (Holocene). Unconsolidated, hummocky deposit of
Trassic Salitral Formation shale that slumped downslope in the recent past (350084 N
4002658 E, NAD 27); vegetation on the deposit is not fully reestablished and Poleo
Creek is downcutting through the deposit.
Qal Alluvium (Holocene). Unconsolidated clay, silt, sand, and gravel deposited in
major modern drainages and tributaries; up to 5 m thick.
Qes Eolian and alluvial deposits (Holocene). Unconsolidated windblown tan-tobrown silt and clay deposited in low-elevation spots and on pediment surfaces. Fluvially
reworked; contains lenses of gravel. Usually 1 to 3 m thick, but can be 10 m thick.
Qc
Colluvium (Holocene). Hillslope colluvial deposits composed of pebble to
boulder size, unconsolidated debris derived from local volcanic and sedimentary rocks.
Qcbt designates colluvium composed mainly of Bandelier Tuff. Qc refers to colluvium
made up of a variety of lithologies. Up to 35 m thick.
Terrace deposits (middle Pleistocene to Holocene). Alluvial silt, sand, cobble,
Qtn
and boulder deposits of rounded to subrounded local Mesozoic sandstone and wellrounded Proterozoic quartzite recycled out of older (Permian Cutler Group or Miocene
Abiquiu Formation) deposits. The two highest terraces contain 10 to 20% Pedernal Chert
derived from the Miocene Abiquiu Formation. At least three terrace levels (1= oldest, 3 =
youngest) are present along the Rio Puerco and Salitral Creek, one at 49 m, one at 36 m,
and one at 12 m above modern grade. 1 to 3 m thick.
Qpn
Pediment gravels (middle Pleistocene to Holocene). Unconsolidated deposits
of angular to subangular pebbles to boulders of Mesozoic sandstone, limestone and
gypsum resting on surfaces graded to the level of the highest terraces (1= oldest, 3 =
youngest. The largest surface, covering several km2, is on Poleo Mesa, which is cut on
the approximate contact between the Poleo and Petrified Forest formations of the Chinle
Group. Most of the Poleo Mesa pediment surface is covered with eolian silt (Qe).
Approximately 1 to 10 m thick.
Q1s Landslide deposits (middle Pleistocene to Holocene). Unconsolidated, unsorted
deposits composed of locally derived, relatively cohesive blocks of bedrock.
Landslides along the escarpment of the Rio Puerco in the south-central part of the
quadrangle are composed of blocks of Poleo Formation, which typically are rotated so
that tops of the blocks dip toward the canyon rim, and the slides sole into the underlying
shales of the Salitral Formation. Numerous remnants of once extensive landslide deposits
are preserved on and along the base of Mesa Alta escarpment in the northern part of the
quadrangle. The base of the landslides often rests on shales of the Jurassic Summerville
Formation or Triassic Chinle Group, and top is typically hummocky. The distinctive
composition of these landslides, made up of gypsum, limestone, and sandstone debris,
indicates they were derived locally from Jurassic and Cretaceous strata to the north.
These landslides were deposited either on older alluvium (Qoa) sediments or directly
upon mudstone of the upper Chinle Group. Remnants commonly possess a sinuous,
linear distribution extending away from the escarpment. The landslide debris appears to
have, in places, flowed in narrow channels incised into Qoa and TRcu that parallel, but
are topographically above, the present system of arroyo drainages. These deposits may
be up to 35 m thick.
Qoa Older Alluvium (middle to late Pleistocene). Ridgely (1979) used the term
“older alluvium” for unconsolidated Quaternary sediments on the Arroyo del Agua
quadrangle between the Mesa Alta escarpment, northern Mesa Montosa, and Salitral
Creek. This unit is composed of two distinct, but complexly interbedded facies that are
not mapped separately. One facies, which can make up more than 50% of the deposit, is
a brown to reddish-brown siltstone with scattered lenses of gypsum and sandstone gravel
and carbonate nodules. The red-brown silt is likely reworked from upper Chinle Group
mudstone. Paleosols are frequently preserved. Black to dark brown siltstones
interbedded with white fine-grained carbonate deposits that superficially resemble
volcanic ash are present in at least four localities across the area. The fine-grained facies
most commonly overlies the second facies, but in places, it underlies it. The second facies
is a sandy to silty, pebble to cobble unconsolidated gravel in channels that cut either into
the underlying Petrified Forest Formation of the Chinle Group or into the fine-grained
facies. Cut-and-fill channel structures are common. The rounded to angular clasts in the
gravel are local Mesozoic sandstone, limestone, or gypsum. The clasts are generally < 20
cm, but boulders up to <80 cm can occur locally. Minor amounts of well-rounded pebbles
of Precambrian quartzite are locally present in the gravel. These pebbles are likely to
have been derived from conglomeratic beds in the Cretaceous Burro Canyon Formation.
The older alluvium is present south of the east-west oriented Mesa Alta escarpment that
dominates the northern part of the quadrangle, and the alluvial units appear to be
juxtaposed against the upper Chinle Group and are clearly overlain by landslide deposits
derived from the escarpment. The clasts become more rounded south of the escarpment.
In places, the upper fine-grained facies appears to form a fan that dips 5 to 10° south or
southeast of the escarpment. Pebble imbrication measurements suggest a meandering
braided stream channel system trending southeast. Where exposed along incised arroyos,
a minimum thickness of 10 m is indicated.
Cretaceous
Cretaceous stratigraphy on the Arroyo del Agua quadrangle follows that of Landis and
Dane (1967), Saucier (1974) and Owen et al. (2005). The intertongued Dakota-Mancos
succession is referred to here as the Dakota Formation for mapping purposes, because
most of the Dakota members and all of the Mancos members are generally too thin to
map separately. Furthermore, the Mancos member that is present (Clay Mesa member) is
very sandy, so it is treated as a member of the Dakota Formation.
Kd
Dakota Sandstone (Late Cretaceous). (includes Clay Mesa Member of Mancos
Shale, of the intertongued Dakota-Mancos succession). Tan to yellow-brown quartzose
sandstone, dark gray and brown carbonaceous shale, and minor greenish gray mudstone
and bentonite. Members include, from lowest to highest (oldest to youngest): Encinal
Canyon, Oak Canyon, Cubero, and Paguate members. The Encinal Canyon Member is
highly variable in thickness, ranging from 0 to 18 m and averaging 2 to 4 m. This tan
cross-bedded quartz sandstone, with thin to medium bedding, commonly has woody plant
impressions at the upper contact. Bioturbation is not common in the Encinal Canyon
Sandstone. The fine- to medium-sized sand grains are subangular to subround and wellsorted. The Oak Canyon Member is a black, muddy siltstone interbedded with thin (<1
m) beds of ledgy and often lenticular, white to orange, cross-bedded, bioturbated
sandstone. The Cubero Member is a white, massive, thick-bedded, bioturbated
sandstone that is 7-8 m thick. The Clay Mesa Member (of the Mancos Shale) is black
sandy shale to shale with thin (2-3 cm) beds of ripple-laminated sandstone that is 1-3 m
thick. The Paguate Member is orange to tan, with fine-to medium- grained, subangular,
well-sorted sand grains. The Paguate Sandstone is often intensely bioturbated, but in
places remnant cross-bedding, ripple marks, and thin to thick bedding is preserved. It
forms a bold cliff along exposed escarpments of Mesa Alta and is 25-30 m thick. The
Dakota Sandstone is 40 to 56 m thick.
c
Unit Descriptions for the Arroyo del Agua 7.5' quadrangle
Tr
A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
P
NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES
9400
9000
8600
8200
7800
7400
7000
6600
A'
Pinabetal
fault
pC
IPgb
Pce
MesaPoleo
Salitral Creek
MesaMontosa monocline
TRcp
Pca
Pce
TRcl
Coyote
monocline
MesaMontosa
TRcp
IPgb
Pca
Pca
IPPce
pC
IPPce
IPgb
TRcl
TRcp
TRcp
TRcl
TRcl
IPgb
Pca
IPPce
pC
IPgb
pC
pC