NEW MEXICO BUREAU OF MINES AND MINERAL RESOURCES
A DIVISION OF NEW
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NMBMMR Open File Map Series
OF–GM–21
Map last modified 29 February 2000
MEXICO INSTITUTE OF MINING & TECHNOLOGY
EMA
Dr. Paul W . Bauer
Geologic Mapping
Program Director
Dr. Peter A. Scholle
Director and State Geologist
(D
DALIES QUADRANGLE
IE
AL
)
NW
106° 52' 30"
34° 52' 30"
3
29
000m
445 000 METERS (CENTRAL)
3
E.
30
3
33
50'
3
32
Qch7
Qch6
Qch3
3
34 (WIND MESA)
Qe
D U
3
35
Qal
36
3
37
47' 30"
R. 1 E.
D U
Qch1
R. 2 E.
Qac
QTui
Qch3
Qed
Qec
QTsi
Qac
Qch1
Qac
Qe
Qk
Qfp
Qed
Qec
Qch1
QTsi
Qe
Qk
Qec
Qch3
Qec
Qac
Qe
Qac
QTui
QTui
Qac
Qp
K 12,110
TD 16,346
?
Qlds
Qal
Qal
QTsi
38
Qae
58
Qch6
38
58
Qac
Qch3
Qec
Qec
Qch3
Qae
Qe
Qk
Qch4
Qe
Qka
Qae
QTui
Qch1
Qal
Qlds
Qal
Qac
Qe
Qka
?
Qp
Qae
Qch4
QTsi
38
57
Qch3
Qch3
Qac
Qae
Qch4
QTsi
QTsi
Qch3
QTsi
QTsi
Qe
Qk
Qac
Qed
Qpti
Qae
QTsi
Qae
Qch4
Qed
Qpti
Qed
QTsi
55
Qe
QTsi
t
Qpt
Qed
38
55
Qal
Qe
QTsi
Qed
Qpti
Qe
Qae
Qed
Qe
Qpti
Qal
Qpti
Qpt
SE
Qe
Qed
Qpt
QTui
IS
M
Qed
IC
LI
-2
LL
Qal
Qe
Qpti
Qls
NE
Qal
LL
-1
53
Tl1?
Qe
Qpti
Eolian sand and piedmont alluvium (Pleistocene-Holocene)—Inset in canyons below Los Lunas
volcanoes and piedmont apron (Qpt).
Qe
Qpt
Eolian sand and piedmont alluvium (Pleistocne-Holocene)—On piedmont apron surrounding Los
Lunas volcanoes.
Qe
QTsi
Eolian sand and fine-grained facies of Isleta Reservation (Pleistocene-Holocene)—Eolian sand
overlying fine-grained facies of Isleta Reservation.
Qe
QTui
Eolian sheet and the sand and gravel facies of the Rio Puerco fluvial deposits of the Santa
Fe Group (Pleistocene-Holocene)—Eolian sand on sand and gravel facies of the Rio Puerco fluvial
deposits of the Santa Fe Group.
I
7
7
Qlv1
Qae
Qld
Qec
Qe
Qlds
Qec
Qls
Qe
Qld
?
Qlv1
Qlv4
Qed
Qka
53
Qae
Qlv4
Qls
38
Qlv2
Qec
Qlv2
?
Qlv1
Qlv1
Tl1
Qe
Qka
Qal
SM
Qe
Qpti
Qls
Qld
Qlv3
SE
Qlv2
?
Qld
Qed
Qpt
Tl1
Qed
Qls
Qls
417
Qed
Qpt
54
Qed
Tl1
a
38
Qls
?
Qec
Qlv4
Qlv1
QTui
?
Qed
Qfp
Qlv1
?
Qlds
?
38
52
?
Qlv1
38
52
Qls
QTui
7
Qe
51
Qed
Qka
Qpt
Qal
Qe
Qld
Qls
5
Qls
Tl1
Qal
Qe
Qpti
38
51
Qae
Qe
QTui
Tl1
QTui
38
Qlds
Qpti
25
Qls
Qk
Qe
Qld
Qed
Qec
Qlv4
Qls
QTui
Qec
10
Qe
Qpti
Qls
Qe
Qpti
Qls
a
Qed
Qpt
Qae
Qlv3
Qpti
Qls
15
Tl1
Qlv4
Qed
Qpt
Qe
Tl1
Qec
t
Qe
Qpti
Tl1
Qe
QTui
4
Qe
50
Qe
Qpt
Qe
Qka
Qe
Qed
Qka
?
Qae
QTui
Qch7
Qae
K 7,220
TD 8,495
?
Qed
38
49
Qe
Qed
38
49
Qfp
Qae
Qal
?
Qe
QTui
Qka
Qed
Qae
Tl1
Qed
QTui
Qed
Qe
Qka
Qe
QTui
Qk
Qe
Qed
?
417 500 METERS
(CENTRAL)
Qae
Qae
Qal
Qch6
38
48
Qed
Qe
Qe
38
48
Lava flow 6 of Cat Hills (Pleistocene)—Dark-gray (N3) to grayish black (N2) fine- to mediumgrained, vesiculated, basaltic lava flow. Groundmass is microgranular mixture of plagioclase,
clinopyroxene, opaques (ilmenite and magnetite), and olivine. Contains approximately 6 percent
phenocrysts of olivine (70 percent) to about 3 mm, and plagioclase (30 percent) to about 2 mm.
Characterized by ridges and grabens that in some areas form a triple junction. These grabens typically
are filled with eolian sand that in some cases have allowed trees to grow within them. Mapped as
Qb3a by Kelley and Kudo (1978). Estimated thickness as much as 50 m.
Qka
Qe
Qka
Qch5
QTui
Qac
Qae
Qed
Qae
Qal
Qed
Qfp
Qe
38
47000m N.
Qed
Qed
3
29
920 000 METERS (WEST)
Qe
Qld
Qal
QTui
3
50'
31
3
(BELEN)
35
Qch4
3
47' 30"
37
3
38
452 500 METERS (CENTRAL)
3
39000m E.
34° 45'
106° 45'
D. J. McCraw and P. Brown: digital cartographic production
NW
EN
(B
EL
1
MN
0.5
0
1 MILE
GN
1000
0
1000
2000
3000
4000
5000
6000
7000 FEET
NEW MEXICO
11°
1° 02'
196 MILS
18 MILS
1
0.5
0
1 KILOMETER
CONTOUR INTERVAL 20 FEET
QUADRANGLE LOCATION
Geology of Dalies quadrangle,
Bernalillo and Valencia Counties,
New Mexico
September 1, 1998
29 February 2000 Revision
NATIONAL GEODETIC VERTICAL DATUM OF 1929
UTM GRID AND 1995 MAGNETIC NORTH
DECLINATION AT CENTER OF SHEET
Mapping of this quadrangle was funded by a matching-funds grant from the 1998 STATEMAP
program of the National Geologic Mapping Act coordinated by the U.S. Geological Survey
and the New Mexico Bureau of Mines and Mineral Resources (Dr. Charles E. Chapin, Director
and State Geologist; Dr. Paul W. Bauer, Geologic Mapping Program Manager).
by David W. Love 1 , Florian Maldonado 2, Bruce Hallett 3 , Kurt Panter 4 ,
Charles Reynolds 5 , William McIntosh 1 , and Nelia Dunbar 1
1 New Mexico Bureau of Mines and Mineral Resources, Socorro, NM 87801
2 U.S. Geological Survey, Denver, CO 80225
3 Molder and Associates, Inc., Albuquerque, NM 87106
4 New Mexico Institute of Mining and Technology, Socorro, NM 87801
5 Charles Reynolds Geological Associates, Inc., Albuquerque, NM 87110
Lava flow 4 of Cat Hills (Pleistocene)—Dark-gray (N3), fine-grained, vesiculated, basaltic lava flow.
Groundmass is composed of plagioclase, olivine (may include orthopyroxene with some clinopyroxene)
and opaques (magnetite?). Contains about 3.5 percent phenocrysts of plagioclase (29 percent) and
olivine (71 percent). Mapped as Qb2a by Kelly and Kudo (1978). Estimated thickness as much as
15 m.
E)
D. W. Love: Quaternary and Tertiary sedimentary geology and deformation,
Los Lunas volcanic stratigraphy and deformation, schematic cross section;
F. Maldonado: geology of the Isleta Reservation, particularly lava flows of
Cat Hills and Upper Santa Fe Group units; B. Hallett, K. Panter, W. McIntosh, and
N. Dunbar: geology, geochemistry, and geochronology of Los Lunas volcano;
C. B. Reynolds: seismic profiles LL-1 and LL-2
SCALE 1:24,000
Lava flow 5 of Cat Hills (Pleistocene)—Dark-gray (N3) to grayish black (N2) fine-grained, vesiculated,
porphyritic, basaltic lava flow. Groundmass is microgranular mixture of plagioclase, clinopyroxene,
opaques (ilmenite and magnetite), and olivine. Composed of 6 percent phenocrysts of olivine (51
percent) to about 3 mm, and plagioclase (49 percent) to about 2 mm. Ridges with grabens common
and filled with eolian sand. Flow resembles lava flow 6. Mapped as Qb3 by Kelley and Kudo (1978).
Estimated thickness as much as 25 m.
M
Base from U.S. Geological Survey 1954, photorevised 1976
Universal Transverse Mercator projection, 1983 North American datum, 2,500-meter
grid based on New Mexico coordinate system of 1983, cental and west zones
1000-meter Universal Transverse Mercator grid ticks, zone 13, shown in blue
O
(T
)
34° 45'
106° 52' 30"
Intrusives of Los Lunas (Pliocene?)—Grayish black (N2) very fine-grained, dacitic sill or laccolith
(?). Groundmass is microgranular, containing plagioclase, pyroxene, and + olivine. Vesicles are 210 percent of rock volume and display an anastomosing texture throughout the unit. Mapped as Qia
by Kelley and Kudo (1978). Contacts between slightly different textures within these bodies include
sheets, dikes, and autobreccias. No baked contacts or abundant inclusions of surrounding sediments
have been found. Instead, these bodies have been buried by sediments that incorporate clasts of
these bodies. Therefore, although these bodies are mapped as intrusive, they must have been exhumed,
buried by sediments (Qtui), and currently are being exhumed again.
Lava flow of Los Lunas (Pliocene; 3.88 +0.04 Ma, 40Ar/39Ar plateau age)—Medium dark
gray (N4) at base to grayish black (N2), very fine-grained, vesicular, trachyandesite lava flow.
Groundmass is micro-granular, containing plagioclase, pyroxene, and + olivine. Microphenocryst
phases consist of plagioclase and pyroxene. Flows are massive and generally fractured into large
blocks. Some flows include extensive flow breccia below and in front of the massive part. The lower
medium dark gray base is heavily fractured into thin (5-cm) lensoids, possibly a texture resulting from
cooling and/or shear stress. This unit is restricted to the southwestern portion of the volcano. A massive
flow locally overlies a vent breccia near the south edge of exposures. This vent breccia overlies
another local lava flow. The main flow body overides a dark, dacitic ash in the canyon separating
the old flows from the younger volcano. The flows may be repeated by fault or slump blocks. Mapped
as Ql and Qia by Kelley and Kudo (1978).
Sand, silt, and clay lithofacies of Isleta Reservation (Pliocene-Pleistocene)—Grayish orange
(10YR7/4), grayish yellow (5Y8/4) to yellowish gray (5Y7/2) sand, silt, and clay with minor thin
gravel beds. Exposed thickness about 25 m.
Sand and gravel facies of Isleta Reservation (Pliocene-Pleistocene?)—Composed of a stacked
sequence of alternating grayish-orange-pink (5YR7/2) to very pale orange (10YR8/2) poorly
consolidated intercalated sand, silt, clay, and gravel beds deposited by the ancestral Rio Puerco and
local beds of the Rio Grande (?) exposed along the western margin of the Rio Grande valley. Pebbles
appear to be bimodal in size with 95 percent less than 3 cm in length; the remaining 5 percent ranging
up to 70 cm in length. The small pebbles are predominantly well rounded siliceous bebbles such as
quartzites, jaspers, cherts, chalcedony, and silicified wood, as well as granite, limestone, basalt,
intermediate volcanic rocks, and reworked pelecypods. Larger pebbles, cobbles, and boulders are
predominantly subrounded basalt, granitic rocks carbonate-cemented sandstones (recycled from Santa
Fe Group), Pedernal chert, other sedimentary rocks, and rare intermediate and siliceous volcanic
rocks. Local units north of Los Lunas volcano include a pumice debris flow with scoraceous basalt
clasts and cross-bedded pumiceous sandy gravels with small obsidian pebbles. Fragments of two
species of camels (Blancan land-mammal age; identified by Gary Morgan, New Mexico Museum
of Natural History and Science, oral commun., 1998). Were recovered from an exposure in the central
part of the map. Tul Local unconformity in Qtui related to deformation during emplacement of ash
and Tl1.
Contact, currently solid for digitizing purposes, will be dashed where approximate, dotted where
concealed.
Normal fault, dashed where approximate, dotted where buried
Reverse fault, teeth on upthrown side
Approximate edge of piedmont slope deposits on top of the Llano de Alburquerque west of Los Lunas
volcano
Plunging anticline
Plunging syncline
7
Strike and dip of beds
Horizontal beds
Summit depression
a
t
Small outcrops of Tshirege ash within Qpt
Small outcrops of tephra layers within Qtui
?
Qe
417 500 METERS
(WEST)
Lava flow 1 of Los Lunas volcano (Pleistocene -1.22 ± 0.13 Ma by 40Ar/39Ar plateau age
geochronolgy)—Light gray (N7) at lower 1 m of base to pale brown (5YR5/2) fine-grained, vesiculated
trachyandesite lava flow. Groundmass is microgranular, containing plagioclase, olivine, pyroxene,
and Fe-Ti oxides. Microphenocryst phases include plagioclase, olivine, and pyroxene. Crustal
xenocrysts/xenoliths are common throughout the flow, are subrounded, range in size from 0.5 cm to
6 cm, and represent < 1 percent of the total rock volume. The flow is massive and generally fractured
along concoidal planes. This unit is present across the lower elevations on the north side of the volcano.
The flow generally is less than 15 m thick but is thicker at north edifice, at ponded area on west side
(18 m), and at low northeastern edge of exposures (55 m). Mapped as Qa1, Qa2, and Qa3 by Kelley
and Kudo (1978).
Dalies 7.5’ Quadrangle
White (N9) to bluish-white (5B9/11) thick, stage III-IV (Birkeland, 1984; Machette, 1985)
calcic horizon that has developed at the top of sands and gravels of the QTui unit on the Llano de
Alburquerque. Contains clasts of chert, quartzite, chalcedony, granite, petrified wood, sandstone,
basalt, jasper, limestone, and lava. As much as 2 meters thick.
Lava flow 7 of Cat Hills (Pleistocene)—Dark-gray (N3) to grayish black (N2) very-fine grained,
vesiculated, basaltic lava flow. Groundmass is microgranular mixture of plagioclase, clinopyroxene,
opaques (ilmenite and magnetite), and olivine. Contains approximately 9 percent phenocrysts of
plagioclase (58 percent) to about 2 mm, olivine (41 percent) to about 3 mm, and clinopyroxene (1
percent). Ridges or mounds are common and are characterized by apical grabens that are filled with
eolian sand. Near the cinder cones to the northwest, the flows form hogbacks dipping away from
the cones. Mapped as Qbr by Kelley and Kudo (1978). Dated at 250,000 ± 0.08 years using
40Ar/39Ar (Geochronology Laboratory, New Mexico Institute of Mining and Technology, written
commun. 1997). This date is discordant because the oldest Cat Hills flow (Qch1) is dated at about
100,000 years. Estimated maximum thickness about 30 m.
Scoria deposite of Los Lunas volcano (Pleistocene)—Blackish read (5R2/2) to moderate reddish
brown (10R4/6), fine-grained, scoriaceous and agglutinated trachyandesite pyroclastic breccia.
Groundmass is glassy with 1-2 percent microphenocrysts of plagioclase and quartz. Individual bombs
and lapilli are partially welded to adjoining volcanic fragments. Associated lithics represent 2-5
percent of the total rock volume. This unit mantles the pre-eruption topography and is 2-3 m thick at
a cliff exposure on the norther and eastern sides of the summit.
EXPLANATION OF MAP SYMBOLS
VOLCANIC ROCKS
Cat Hills
Qe
QTui
Qe
Qka
50
Qe
QTui
Qe
Qe
QTui
38
Qld
Qed
Qe
Qka
Qe
Qe
Qka
Tli
Qal
Qe
QTui
Tli
Qe
Qe
Qka
?
QTui
Qe
38
K 2,835
TD 4,223
Qe
Qld
Qae
32
Qpti
4
Piedmont alluvium, talus, and eolian deposits (Pleistocene-Holocene) downslope from Los
Lunas volcanoes—Light brown (5YR6/4), grayish orange (10YR7/4), to very pale orange (10YR8/2),
mixture of unconsolidate, poorly sorted sand, gravel, and talus overlain by eolian sand and talus
blocks. Base of Qpt unconformable on Santa Fe beds and includes boulders of Qlv1 and Tshirege
ash as much as 0.6 m thick (1.22 Ma, from Valles Caldera). Thickness as much as 50 meters.
Qk
Qae
7
Qed
Qka
QTui
Qae
Qed
Qk
QTsi
Stabilized top of Los Duranes Formation known as segundo alto terrace. Contains stage II
calcium carbonate horizone beneath eolian mantle.
Exposures of calcic soil (Pleistocene)—White (N9) to bluish-white (5B9/11) thick, stage II-III
(Birkeland, 1984; Machette, 1985) calcic horizon developed in alluvial and eolian units on alluvial
slopes.
Qal
Lava flow 3 of Los Lunas volcano (Pleistocene)—Medium gray (N5), fine-grained trachyandesite
lava flows. Finely porphyritic with phenocrysts of pyroxene and plagioclase (both up to 3 mm). The
groundmass is holocrystalline, nonvesicular, and contains plagioclase, pyroxene, Fe-Ti oxides, + olivine.
The unit is exposed only on the east side of the volcano where it ranges up to 24 m thick. It overlies
Qlv1 and dscends to the south. It has been truncated on the east side, either by a fault or by bluffcutting erosion of the Rio Grande prior to deposition of the Los Duranes Formation.
Fluvial, alluvial, and eolian deposits of the upper Santa Fe Group (Pliocene-Pleistocene)—
This sequence of sediments represents detritus related to the ancestral Rio Puerco and Rio Grande (?)
that may be equivalent to Machette’s (1978) Sierra Ladrones Formation. The sediments have been
divided into the following mappable facies: sand and gravel (QTui), and finer-grained facies (QTsi)
consisting of sand, silt, and clay with extremely minor lenses of gravel. The finer-grained facies appear
to fill a north-south graben and sag structure within the Llano de Alburquerque.
Los Duranes Formation (Pleistocene) and segundo alto terrace of Rio Grande of Lambert
(1968). Los Duranes Formation is 40 m thick, consisting of coarse cobble gravel at base, overlain
by crossbedded sand, and parallel-bedded fine sand, silt and clay in fining-upward packages. In
deposits on the Isleta Quadrangle to the northeast, at least two separate sand layers show convoluted
bedding similar to seismites (Seilacher, 1969). Local pale gray sand and silt units contain fossil snails.
Qpti
QTui
Qe
Qpti
10
Landslide, talus, and colluvial deposits (Pleistocene-Holocene) on steep slopes adjacent to Los
Lunas volcanoes. Landslides progress downslope from large coherent rotated toreva blocks of lava
to disintegrated talus boulders to colluvial wedges at the base of the slopes. Interstitital eolian sand,
reworked sediments (Qtui), and pedogenic stage II to stage IV calcium carbonate accumulations are
common between lava clasts. Some talus includes flow-front breccia extending beyond the lava flows.
QTls includes fluvial volcanically-derived gravel and volcanic talus adjacent to lavas of the older
volcano.
Lava flow 4 of Los Lunas volcano (Pleistocene)—Light gray (N7) to pale brown (5YR5/2) finegrained trachyandesite lava flows. Groundmass is microgranular and microvesicular containing
plagioclase, pyroxene, Fe-Ti oxides, + olivine. Phenocrysts (up to 4 mm) include plagioclase and
pyroxene. Crustal xenoliths are common and are angular to subrounded, making up < 1 percent of
the rock. The unit consists of symmetrical lava lobes that appear to originate from a central depression
(buried crater?) near the main summit of Los Lunas volcano. Lava overlies talus, eolian sand and Qlv1
and Qlv2 on northeast flank of summit. Lava flow 4 overlies Qlv3 on east side of the volcano.
Maximum thickness of the unit is estimated to be 8 m.
SANTA FE GROUP
Eolian sheet and soils of the Llano de Alburquerque (Pleistocene-Holocene)—Eolian sheet sand
overlying soils of the Llano de Alburquerque (described below). Sand is light brown (5YR8/2),
unconsolidated, composed of fine grained, well rounded and well sorted quartz grains. Locally
contains sand and pebbles composed predominantly of chert, quartzite, calcedony, granite, petrified
wood, sandstone, basalt, and limestone derived from the underlying soils of the Llano de Alburquerque
and Qtui.
Piedmont alluvium (Pleistocene) inset along canyons and erosional scarps adjacent to Los
Lunas volcanoes. Light brown (5YR6/4), grayish orange (10YR7/4), to very pale orange (10YR8/2)
poorly sorted sand, gravel, and talus overlain by eolian sand and talus blocks.
Qfp
Qld
Tl1
Qka
Tl1
QTui
Qe
Qka
Qed
Qka
?
Tul
Tl1
Qk
Qed
Qka
Qlds
Qlv4
Qls
Tl1
47' 30"
Tli
Eolian dune (Late Holocene)—Light brown (5YR6/4), grayish orange (10/YR7/4), to very pale
orange (10YR8/2), unconsolidated, fine grained, angular to well rounded, well sorted sand composed
mostly of quartz. Cross-bedding is common. Extended arms of blown out parabolic dunes are found
in the southern three-quarters of the map area where orientation of dunes indicate winds dominantly
from the west-southwest.
Qe
Qpti
Tl1?
Qe
Qpt
38
QTui
Qed
Qpt
Qe
Unconsolidated colluvium and eolian sand (Pleistocene-Holocene) partially covering lava flows
and intrusives. The wind-blown sand and silt and volcanic clasts are typically deposited in topographically
low areas within the lava flows and near fault traces.
Eolian sheet and older alluvium (Pleistocene-Holocene)—Eolian sand on Los Duranes Formation
(Qld - described below).
Qls
Qe
12
SE
240
Qal
a
Qed
Qka
Qae
Qed
Qe
Qpti
Qe
t
Qe
D U
Eolian sheet (Pleistocene-Holocene) with subdued or no dune forms—Light brown (5YR6/4),
grayish orange (10/YR7/4) to very pale orange (10YR8/2), unconsolidated, fine grained, well
rounded, well sorted sand composed mostly of quartz. Sheets are generally fairly thin but thicken
near fault scarps. Locally contains Qka and Qec. Commonly deposits have one or more intervals
of soil development beneath the surface.
Qae
Qal
Qe
Qed
Qka
Qal
Qal
1
54
Playa deposits (Historic and Holocene) on Los Duranes Formation—Deposits are sand, silty
sand, and clay. Sandy lunette poorly developed to northeast, downwind of larger playa.
Qlv1
Qe
Qld
Qae
Qed
Qpti
Qe
Qe
Qka
38
Qlv2
Qlds
Qae
Qed
Qae
NW
Qe
Qpt
Qch1
Qal
Qal
Qed
Qpti
Qka
Qed
Qae
Qae
QTui
Qed
Qe
Qka
Qal
Qe
Qac
Qe
QTsi
Qka
Older alluvial deposit (Holocene and Late Pleistocene)—Sandy and pebbly alluvium and eolian
deposits in tributary drainages and alluvial aprons along lower valley margins. Comprised of interbeds
of sand and gravel deposited as channels, overbanks, and fans. Sand is unconsolidated, yellowish
gray (5Y7/2) to grayish gray (5Y8/4) and contains pebbles. Gravels are unconsolidated, pea- to
cobble-size clasts composed of Qka and clasts eroded from the Qtui unit. Locally includes eolian
sand.
QTui
Qed
Qpti
56
Qch4
38
Qec
Qac
D U
Qlv3
?
Qal
N
E
50'
38
Older alluvial deposit (Holocene)—Comprised of interbeds of sand and gravel deposited as
colluvium and fans on moderate slopes. Sand is unconsolidated, yellowish gray (5Y7/2) to grayish
gray (5Y8/4) and contains pebbles. Gravels are unconsolidated, pea to cobble size clasts composed
of Qla and clasts eroded from the QTsp unit. Locally includes eolian sand. A charcoal sample from
this unit in the adjacent Dalies Northwest quadrangle (Maldonado and Atencio, 1998) to the west
has been dated at 1950 ± 50 years (Jack McGeehin, U. S. Geological Survey, written commun,
1997) using the 14C method.
LI
Qe
Qka
Qe
Qal
Qac
Qe
Qka
Qka
QTui
6
?
Qlds
Qed
Qae
Qk
Qed
Qp
(LOS LUNAS)
57
IC
38
Qlv4
Younger alluvial deposit (Historic, Holocene)—Composed of a stack of beds comprised of yellowishgray (5Y7/2) unconsolidated sorted to unsorted, fine to coarse sand interbedded with gravel beds.
The gravels are composed of clasts of pebble to cobble size, predominantly of calcic soils of the
Llano de Albuquerque (described below) and clasts eroded from the QTui unit. Unit resembles QTui
and Qae units. Deposited in arroyos inset into older alluvial deposit mapped as Qae. Locally includes
eolian sand.
?
Qch4
Lava flow 1 of Cat Hills (Pleistocene)—Dark-gray (N3) to grayish black (N2) fine- to mediumgrained, vesiculated, porphyritic, basaltic lava flow. Groundmass is microgranular mixture of plagioclase,
clinopyroxene, opaques, and olivine. Composed of 6 percent phenocrysts of olivine (78 percent) to
about 4 mm, plagioclase (20 percent) and clinopyroxene (2 percent). Overlies the soils of the Llano
de Albuquerque (Qla). Mapped as Qb1 by Kelley and Kudo (1978) and dated at 0.140 ± 0.038
(Kudo and others, 1977) using the K-Ar method. New 40Ar/39Ar dates are 0.11±0.02 and 0.098
± 0.03 Ma. Estimated thickness as much as 20 m.
Los Lunas Volcano
Qe
Qe
Qk
QTsi
Qal
Qch1
Qe
Qac
Qec
Qch5
427 500 METERS
(CENTRAL)
59
QTui
QTsi
Qch1
38
Qae
Qae
Qac
Qec
Qch5
Qch1
Qac
Qal
Qac
Qec
Historic floodplain of Rio Grande between artificial barriers and valley margins. Consists of silt
and clay overlying sandy overbank and channel deposits. Commonly disturbed by agricultural fields
and subdivisions.
Qlds
Qal
Qch1
SURFICIAL DEPOSITS
Qe
Qec
QTsi
59
Qch1
Qe
Qae
Qch1
Qed
38
Rock chart colors are from Goddard and others (1948). The stratigraphy for the lava flows of the
Cat Hills was modified from Kelley and Kudo (1978). Lava flow 2 of the Cat Hills is not found in this
quadrangle, but occurs in the adjacent Rio Puerco quadrangle to the west. The lava flow sequence
1 through 7 is used here for the sake of clarity in discussion of the Cat Hills lava field. Modal analysis
of Cat Hills lava flows are from Frank Byers, Jr. (U. S. Geological Survey, written commun., 1997).
The stratigraphy of Los Lunas volcanoes is modified greatly from Kelley and Kudo (1978).
Qe
QTui
Qch1
Qch5
430 000 METERS
(WEST)
T. 7 N.
60000m N.
Qch6
E.
Qch1
Qch3
Qch3
Qch5
UNIT DESCRIPTIONS
86 106° 45'
34° 52' 30"
3
D U
38
Qch5
000m
?
Qac
Qch1
Qec
Qec
39
Qe
T. 8 N.
T. 7 N.
3
Qe
Qae
?
U D
U D
Qec
927 500 METERS (WEST)
Qch3
Qed
Qe
QTsi
QTsi
Qch3
Qec
Qec
3
Qe
Qal
(IS
LE
TA
)
S
NEW MEXICO
Qch3
Lava flow 3 of Cat Hills (Pleistocene)—Grayish black (N2) very-fine to medium-grained, vesiculated,
porphyritic, basaltic lava flow. Groundmass is composed of plagioclase, olivine (may include
orthopyroxene with some clinopyroxene) and opaques (magnetite?). Consists of about 6 percent
phenocrysts of olivine (84 percent) to about 5 mm, and plagioclase (16 percent) to about 2 mm.
Vesicles contain microcrystalline filling of quartz, alkali feldspar, and anhydrous minerals. Mapped
as Qb 2 by Kelley and Kudo (1978). Estimated thickness as much as about 20 m.
Oil well. Numbers refer to depth to Cretaceous rocks and total depth
K 2,835
TD 4,223
COMMENTS TO MAP USERS
A geologic map graphically displays information on the distribution, nature, orientation and
age relationships of rock and surficial units and the occurrence of structural features. These
data are derived from geologic field mapping, compilation of published and unpublished
work, and photogeologic interpretation. Locations of geologic unit contacts are not surveyed;
therefore, the accuracy of contact locations depends on the scale of mapping and the
interpretation of the geologist. Portions of the study area may have been mapped at scales
smaller than depicted on the geologic map; therefore, the user should be aware of significant
variations in map detail. 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.
This quadrangle map has been Open-filed in order to make it available as soon as possible.
The map has not been reviewed according to New Mexico Bureau of Mines and Mineral
Resources standards, and due to the ongoing nature of work in this area, revision of this map
is likely. As such, dates of revision will be listed in the upper right corner of the map and on
the accompanying report. The contents of the report and map should not be considered
final and complete until it is published by the NMBMMR.