HYDROGEOLOGIC FRAMEWORK OF
THE MESJLLA BASIN
IN NEW MEXICO AND WESTERN TEXAS
John W. Hawley and Richard P. Lozinsky
New Mexico Bureau of Mines and Mineral Resources
New Mexico Institute of Mining and Technology
Socorro, New Mexico
Open-File Report 323
1992
ABSTRACT
The two major objectives of this study of the Mesilla Basin between Las Cruces,
New Mexico and the International Boundary zone west of El Paso, Texas were (3.) to
develop a detailed conceptual model of the basins hydrogeologic framework that is
baaed on a synthesis of available geological, geophysical, and geochemical data, and (2)
to present that information in a format suitable for use by the U.S. Geological Survey,
Water Resources Division (USGSWRD) in developing an up-to-date numerical model
of the groundwater flow system. The basins hydrogeologic framework is graphically
portrayed in terms of (1) the lithologic character, geometry, and geologic history of
basin-fill deposits; and (2) the bedrock units and structural features that form the basin
boundaries and influence intrabasinal depositional environments. The basic
“architecture” of mappable subdivisions of basin deposits that can be defined in terms of
their aquifer properties is characterized in the conceptual model.
The Santa Fe Group forms the bulk of basin-filling deposits and the major
aquifer system of the region. It comprises a very thick sequence of alluvial, eolian, and
lacustrine sediments deposited in intermontane basins of the Rio Grande rift stru%ural
province during an interval of about 25 million years starting in late Oligocene time.
Widespread filling of several structural subbasins, which in aggregate form the Ml-silla
Basin, ended about 700,000 years ago (early Middle Pleistocene time) with the onset of
Rio Grande (Mesilla) Valley incision. Post-Santa Fe deposits include (1) inset valley fill
of the ancestral Rio Grande and tributary arroyos that forms terraces bordering the
modem floodplain, and (2) river and arroyo alluvium that has been deposited since the
last major episode of valley incision in late Pleistocene time (about 15,000 to 25,010
years ago).
The three basic hydrogeologic components of the Mesilla Basin model con-p&e:
1. Structural and bedrock features that include basin-boundary mountain uplifts,
bedrock units beneath the basin fill, fault zones within and at the edges of basin that
influence sediment thickness and composition, and igneous-intrusive and -extrusive rocks
that penetrate or are interbedded with basin deposits. 2. Hydrostratigraphic units which
are mappable bodies of basin and valley fill that are grouped on the basis of or&i-i and
position in a stratigraphic sequence. Genetic classes include ancestral-river, present
river-valley, basin-floor playa, and Piedmont alluvial fan deposits. Rock-&at&rap1 ic
classes in&de units deposited during early, middle and late stages of rift-basin filling
(i.e. lower, middle and upper Santa Fe Group), and post-Santa Fe valley fills (e.g.
channel and floodplain deposits of the Rio Grande, and fan alluvium of tributary
arroyos) . 3. Lithofacies subdivisions are the basic building blocks of the model. II- this
study, basin deposits are subdivided into ten lithofacies (I through X) that are ma?pable
bodies defined on the basis of grain-size distribution, mineralogy, sedimentary
structures, and degree of post-depositional alteration. They have distinctive geophrsical,
geochemical, and hydrologic attributes.
The hydrogeologic framework of the Mesilla Basin area is graphically presented
in map and cross-section format (Plates 1, 16 and 17). Supporting stratigraphic,
i
lithologic, petrographic, geophysical, and geochemical data from 61 wells are illustrated
in stratigraphic columns and hydrogeologic sections (plates 2 to 15). A new
computer-generated graphics system was utilized in the presentation of these data.
Tables 4a and 4b summarize the subsurface information used in this study, including (1)
well location and depth; (2) ground-water levels; (3) drill-stem sample intervals; (4)
selected data on ground-water chemisq; and (5) data sources. Major hydrostratigraphic
units and aquifer zones sampled are also identified in Tables 4a and 4b.
The report has four major narrative sections (I. Introduction; II. Geologic
Setting; 111. Sand-Fraction Petrography; and IV. Conceptual Model), a wmprehexive
reference list, and two appendices (A. Basic petrographic data, and B. Preliminary
hydrogeologic cross sections extending into adjacent parts of the Jornada del Muerto
and Hueco basins). Previous work on basin hydrogeology and study methods are
covered in Section I. A team approach was used in the analysis of borehole (geol~~gical,
geophysical, and geochemical) data to develop the final conceptual model of
hydrostratigraphic and lithofacies unit distribution.
Section 11provides a general geological overview of the MesiUa Basin region
including the structure of flanking mountain uplifts and relationship to contiguous basin
areas in New Mexico, Texas, and Chihuahua. Emphasis is on the past 25 million years
of geologic time when major structural and topographic elements of the present
landscape formed. The interval was characterized by regional extension of the earth's
crust, and differential uplift, subsidence and tilting of individual crustal blocks along
major fault zones to form internally complex basins and ranges. This continental "rifting"
process produced the Rio Grande rift structural zone that extends from southern
Colorado to western Texas and northern Chihuahua. A major contribution of this study
has been the significant improvement in definition.of the physical limits of the MesiUa
Basin and its component subbasins. Much of the information on bedrock distribution
and geologic structure was derived from published maps and cross sections, with
supplemental data from unpublished geophysical and geothermal surveys. Seismic
reflection profiles specially prepared for the USGS-WRD at two sites in the lower
MesiUa Valley have also been utilized in this study.
Rift basin fill comprising the Santa Fe GIOUPhas a maximum thickness of about
3,000 ft (915 m) in the Mesilla Basin. The lower and middle parts of the Santa Fe. form
the bulk of the basin fill and were deposited in an internally drained complex of tllree
subbasins that were initially separated by a central (north-trending) intrabasin upl'ft
(Eastern, Northwestern, Southwestern subbasins, and Mid-basin uplift on Plate 1)
Eolian sands and fine-grained playa-lake sediments are major lithofacies. These wits
are locally well indurated and only produce large amounts of good quality ground water
from buried dune sands (lower Santa Fe) in the eastern part of the basin beneath the
MesiUa Valley. Poorly consolidated sand and pebble gravel deposits in the middle to
upper part of the Santa Fe Group form the most extensive aquifers of the area.
Widespread channel deposits of the ancestral Rio Grande fist appear in upper S m t a
Fe beds that have been dated at about 3.5 d o n years (Ma) in southern New M x i w
and 2.5 Ma in western (Trans-Pews) Texas.
ii
Expansion of the Rio Grande (fluvial) system into upstream and downstrem
basins, and integration with Gulf of Mexico drainage in the early to middle part of the
Quaternary (Ice-Age) Period about 700,000 years ago led to rapid incision of the
Mesilla Valley and termination of widespread basin aggradation (ending Santa Fe
Group deposition in the Mesilla Basin). Cyclic stages of valley cutting and filling are
represented by a stepped-sequence of valley border surfaces that flank the modem
valley floor. Fluvial sand and gravel deposited during the last cut-and-€ill cycle f o m a
thin, but extensive shallow aquifer zone below the Rio Grande floodplain. Recen? fluvial
sediments are locally in contact with ancestral river facies in the upper Santa Fe Group,
particularly in the northern Mesilla Valley. They form the major recharge and discharge
zones for the basin's ground water, and are quite vulnerable to pollution in this
urban-suburban and irrigation-agricultural environment.
Structural deformation along subbasin boundaries and changes in topographic
relief between deeper basin areas and flanking uplifts continued throughout the lite
Cenozoic. During early stages of basin filling (lower Santa Fe deposition) many of the
present bounding mountain blocks had not formed or had relatively low relief. Tl ickest
basin-€ill deposits (up to 1500 ft [455 m] of the middle Santa Fe Group) were emplaced
between 4 and 10 million years ago during most active uplift of the
Organ-Franklin-Juarez range and the Robledo Mountains, and subsidence of the
Eastern (La Union-Mesquite) subbasin. The major basin-bounding fault zone (MIsilla
Valley) is now covered by the recent river floodplain deposits.
The petrographic investigations described in Section III emphasize the
fundamental properties of rock fragments and mineral grains that in aggregate f o m the
various lithofacies subdivisions of the five hydrostratigraphic units (Tables 1 and 2).
Cuttings from the Afton (MTl),Lanark (h4l'2), La Union ( M n ) , and Noria (MT4)
were analyzed initially with a binocular microscope in order to construct a stratignphic
column for each of these key wells (Plates 12-15) and to determine intervals
(approximately every 100 ft, 30 m) where subsamples of representative sands would be
collected for thin-section petrographic analyses. Samples were also collected from
representative sandy intervals in the two wells in the Canutillo Field (CWFLD an4 4D)
and from six outcrops of the Upper and Middle Santa Fe units. Petrographic anal rsis of
sand samples analyzed from the six water wells and from outcrop areas in the.Mehla
Basin shows that the basin €ill was derived from more than one source terrane. The
abundance of plagioclase (zoned and twinned) and andesitic lithic fragments strorgly
suggest an intermediate volcanic source area for most of the detrital material. Chert,
chalcedony, and abundant quartz (many well rounded with overgrowth rims) indicate
reworked sedimentary units as another major source. A granitic source area is also
suggested by the presence of microcline, strained quartz, and granitic rock fragmeJts.
The paucity of metamorphic-rock fragments and tectonic polycrystallinequartz rules out
a metamorphic terrane as a major sediment source.
It appears that even in early to middle Santa Fe time (Miocene) the centra'
Mesilla Basin area was receiving sediment from a very large watershed. A much larger
source region was also available for sand and finer grain-size material when the
mechanism of eolian transport is taken into account. By middle Pliocene time the
iii
ancestral Rio Grande was delivering pebble-size material to the basin from source
terranes as far away as northern New Mexico (e.g. pumice and obsidian from the Jemez
and Mount Taylor areas). In most cases, visual and binocular microscopic examination
of the gravel-size (>2mm) fraction is still the best way to establish local versus re.giona1
provenance of coarse-grained fluvial and alluvial deposits.
The conceptual hydrogeologic model is described in detail in Section IV and
illustrated on Plates 1, 16, and 17 with supporting data and interpretations on Plates 2
to 15.The basic hydrogeologic mapping unit used in conceptual model development is
the hydrostratigraphic unit. It is defined in terms of (1)environment of deposition of
sedimentary strata, (2) distinctive combinations of lithologic features (lithofacies) such
as grain-size distribution, mineralogy and sedimentary structures, and (3) general time
interval of deposition. The attributes of four major classes into which the area’s basin
and valley fi b have been subdivided are defined in Table 1. The Upper, Middle, and
Lower hydrostratigraphic units of the Santa Fe Group roughly correspond to the
(informal) upper, middle and lower rock-stratigraphic subdivisionsof Santa Fe Group
descnied in Section II. The other major hydrostratigraphic unit comprises Rio Grande
alluvium of late Quaternary age (<15,000 yrs) that.foms the upper part of the re.gional
shallow-aquifer system.
The ten lithofacies subdivisions that are the fundamental building blocks of the
model are defined primarily on the basis of sediment texture (gravel sand, silt, chy, or
mixtures thereof), degree of cementation, and geometq of bodies of a given textural
class and their relative distribution patterns. Lithofacies I, 11, ID[, V, and VI are
unconsolidated or have zones of induration (strong cementation) that are not
continuous. Clean sand and gravel bodies are major constituents of facies I, 11, V, and
VI; while clay or cemented sand zones form a significantpart of facies 111and IV.
Subdivision N is characterized by thick eolian sand deposits of the lower Santa Fe unit
(LSF) that are partly cemented with calcite. Coarse-grained channel deposits of the
modern and ancestral Rio Grande (lithofacies I and II)are the major component: of
the upper Santa Fe (USF) and river-alluvium (RA) hydrostratigraphic units. They form
the most important aquifers and potential enhanced-recharge zones in the-basin.
Lithofacies VI and W I are partly to well indurated piedmont-slope.deposits; while
facies IX and X comprise thick sequences of fine-grained basin-floor sediments that
include playa-lake beds.
Unconsolidated deposits make up the bulk of the middle and upper Santa Fe
Group and all of the recent valley fill in the MesiUa Basin. Textural classes include
sand, gravelly-sand, silt-clay, and sandy to gravelly materials with a siltclay matrix
Secondary calcite and gypsum are the primaIy cementing agents in the basin fill,
however, continuously indurated zones are uncommon except in basal parts of the. Santa
Fe section. Coarse-grained fan alluvium and debris-flow deposits, with gravel prirrarily
in the pebble- to cobble-size range ( < l o in., 25 cm), are confined to narrow piednont
zones near the basin margins (lithofacies V-VIII). Indurated parts of these deposits
comprise facies VII and VrII. Widespread fluvial deposits of the ancestral Rio GTande
form much of the upper Santa Fe Group (unit USF, facies Ib and II) as well as the
upper Quaternary fill of the inner Mesilla Valley (unit RA, facies IV). Fluvial materials
iv
beneath the Rio Grande Valley floor constitute the major shallow aquifer system
Outside the valley area, however, most of the ancestral river deposits are in the vadose
zone.
Interbedded sand and silt-clay deposits of the Middle Santa Fe Unit (MSU,
primarily lithofacies I
I
J
J
form the basin's thickest and most extensive aquifer system (the
"medial" aquifer in this report; Tables 4a and b). This unit is as much as 1000 ft (305 m)
thick in the eastern (La Union-Mesquite) subbasin (Plates 3-5, 10, 11, 16b-417a\.
Well-sorted fine to coarse sand deposits of lithofacies IV make up a significant part of
the lower Santa Fe Unit (LSU) and are here interpreted as being primarily of eo.!ian
origin. These partly-indurated beds are as much as 600 ft (185 m) thick in the eastern
(La Union-Mesquite subbasin); and they may be 900-1000 ft (275-305 m) thick in the
southwestern subbasin immediately east of the east Potrillo fault zone (Plates 3-5: 7, 10,
11, 16b-e, 17a).
All basin fill units (USF, MSF, LSF) become finer grained to south; and fine- to
medium-grained basin-floor facies, with only minor amounts of gravel, dominate the
basin fill section in the international boundary zone west of Cerro de Cristo Rey (Plates
6, 7, and 16e; facies ID, IX and X). Most of the Upper Santa Fe hydrostratigraphic unit
(USF) in that area is in the vadose zone; and sand beds in the basal Upper Santa Fe
unit and upper part of the Middle Santa Fe unit (MSF, lithofacies III) appear to be the
only major aquifer east of the Mid-Basin uplift. Lithofacies IV in the Lower Santa Fe
hydrostratigraphic unit (LSU) may also be a potential deep aquifer in the Southwestern
subbask, but this zone has not yet been tested for either quantity or quality of grmnd
water production.
Assignment of specific hydraulic conductivity ranges to individual lith0facie.s
subdivisions is beyond the scope of this investigation. However, as a first approximation,
the following general ranges appear to be reasonable: 1. Conductivities of lithofacies I
and I1 are relatively high (30 to 300 ft/day, 10-100 m/day); 2. Lithofacies IX and 2- and
well-cemented sandstone and fanglomerate zones in facies VI1 and VIZI will defiritely
have very low conductivities (usually much less than 0.3 ft/day, 0.1 m/day); 3.
Conductivities in uncemented sand layers in lithofacies Ln. and N,and sand and gravel
beds in facies V through VI11 should primarily be in the intermediate range (0.3 to 30
ft/day, 0.1-10 m/day).
V
CONTENTS
Section
.................................................
i
INTRODUCTION ............................................
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Previous Work on Basin Hydrogeology ..............................
Methods and Techniques .......................................
DataCollection and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1
3
. . S B A
I.
Page
8
8
Drill Cuttings and Thin Section Ann2ysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
Digitizhg Borehole Geophysical Logs ................................
9
Hydrostratigraphic Unit Correlation and Conceptual Model Development ....... 9
Well Numbering System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
II.
GEOLOGIC SETTING OF THE MESILLA BASIN . . . . . . . . . . . . . . . . . .13
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Basin Structure and Bedrock Units ...............................
13
Bedrock Units of Basin-MarginUpl@ ..............................
16
Bedrock Unils Beneath the Basin Fill ...............................
17
BasinFill Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
Santa Fe Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
Post-Santa Fe Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20
111.
SAND-FRA(=TION PETROGRAPHY ............................
21
21
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Methods and Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
Preliminary Dd-Cutting Analyses .................................
21
Thin Section Sample Collection and Preparation .......................
21
Thin Section Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
Sand Petrology of Selected Samples ofWell Cuttings . . . . . . . . . . . . . . . . . .25
Comparison with Santa Fe Outcrops ..............................
25
Provenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
IV.
A CONCEPTUAL HYDROGEOLOGIC MODEL OF THE MESILLA BASIN
... 30
30
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hydrostratigraphic Subdivisions of Basin and Valley Fills . . . . . . . . . . . . . . 31
Lithofacies Subdivisions of Basin and Valley Mus ....................
31
Structural and Bedrock Elements of the Hydrogeologic Framework . . . . . . . . 33
Basin-Boundary Faults andSanta Fe Group Thickness . . . . . . . . . . . . . . . . . .34
Structural Influences on Intrabasin Sedimentntion Patterns
. . . . . . . . . . . . . . . .34
v.
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction ................................................
ReportFormat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SectionI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Section17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SectionIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES
..................................................
APPENDIX A
BasicPetrographicData
.......................................
37
37
38
38
38
39
40
43
44
51
APPENDIX B
Hydrogeologic Cross Sections of the Mesilla Bolson Area, Doha Ana County,
NM and El Paso County, TX (NMBMMR Open-file Report 190) . . . . . . . Pocket
vii
FIGURES
Figure 1.
Location of study area
Well
2.
.....................................
numbehg systems
2a. Diagramshowingsystem
2b.Diagramshowingsystem
3.
4.
2
of numbering wells in NewMexico . . . . . 10
of numbering wells in Texas . . . . . . . . . . 11
Index map of MesillaBasin area showing locations of major
boundary and intrabasin faults, adjacent mountain uplifts,
and geologiccrosssections (Fig. 4) ..........................
14
Diagrammaticgeologic cross section of the northern and
central Mesillabasin. ....................................
15
Figures 5-6. Ternary diagrams of sand-fraction petrography (thin-section
point-count data, Tables 5 and 6) for well cuttings from
representative Santa Fe hydrostratigraphic units at:
5.
6.
Figure 7.
M o n (MT l), Lanark (MT 2),and
Canutillo WellField (CWF 1D) ............................
26
La Union (MT 3), Noria (MT 4), and
Canutillo WellField (CWF 4D) ............................
27
Ternary diagrams of sand-fractionpetrography(thin-section
point-count data, Tables 5 and 6) for samples from
representative Santa Fe Group outcrops .......................
28
TABLES
Table 1.
2.Key
Key to hydrostratigraphic units in the MesillaBasin
(Plates 2-17, Tables 3 and 4) ................................
4
to bedrock units and upper Cenozoicvolcanics
(Plates2-17) ............................................
5
3.
Well
Lithofacies subdivisions of basin- and valley-fiU
hydrogeologic units, and their Occurrence in
lithostratigraphic and hydrostratigaphic units in the Mesilla
Basin (Plates 2-17) .......................................
4.
Selected
Data ...................................
4a. MesillaBasin,NewMexico
4b.
Mesilla
Valley,
Texas
5.
Point-count grain parameters. Modified from Dickinson (1970)
6.
Means (x) and standard deviations (s) of point counts on
water well and outcrop samples. .............................
6
Pocket
. . . . . . 23
24
PLATES
Plate 1.
Index map to Mesilla Basin showing major structural
features and locations of selected wells, hydrogeologic cross
sections, and outcrop sample sites (Table 4, Plates 2-17,
AppendixA) .......................................
Pocket
Plates 2-11. Hydrogeologic sections, with borehole geophysical and
geochemical data ....................................
Pocket
Plate 2.
Las Cruces Fairground to Fire Station
3.
Afton to Mesquite
4.
Aden to La Tuna
5.
La Union to Vinton
6.
Noria Test to Mesa Boulevard
7.
Potrillo Mountains to Noria Test
8.
Afton Test to Noria
9.
Las Cruces to Santa
Teresa
10.
Las Cruces Fire Station to Vado
11.
Vado to Lizard
Plates 12-15.Geological
Data on TestWells
........................
Pocket
Afton Test Well(25.1.6.333;MT1)
Plate 12.
Ml2)
13.
Lanark Test Well
(27.1.4.121;
14.
La Union Test Well
(27.2.13.331;
15.
Noria
MT3)
Test Well
(28.1.34.414;
MT4)
Plate 16.Hydrogeologicsections
(E-W) of the MesillaBasin, Las
Cruces to El Paso area, showing inferred distribution of
major hydrostratigraphic and lithofacies units, and fault
zones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16a.
16b.
16c.
16d.
16e.
Pocket
Plate 2 section area (Las CNWSFairgrounds to Fire Station)
Plate 3 section area (Afton to Mesquite)
Plate 4 section area (Aden to La Tuna)
Plate 5 section area (La Union to Vinton)
Plates 6 and 7 section areas (Mesa Boulevard to Noria Test to P ~trillo
Mountains)
(N-S) of the MesillaValley and westPlate 17.Hydrogeologicsections
central Mesilla Basin areas, showing inferred distribution of
major hydrostratigraphic and lithofacies units, and fault
zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pocket
17a. Plates 10 and 11 section area (Las Cruces Fire Station to Vado t?
Lizard)
1%. Plate 9 section area (Las Cruces to Santa Teresa)
17c. Plate 8 section area (Afton Test to Noria)
X
I. INTRODUCTION
With ever-increasing demands on the ground-water resources of the Mesilla
Basin there is a continuing need for a better understanding of the hydrogeologic
framework of deposits that form one of the major aquifer systems of the region. The
area (Fig. 1) includes the major centers of population and potential economic growth in
the southern New Mexico, Trans-Pecos Texas and north-central Mexico region (I=
Cruces, El Paso, and Ciudad Juarez). From a water-supply perspective, both the private
and public sectors of society (except for irrigation agriculture) rely solely on grould
water.
At a minimum, characterization of basin hydrogeology should include detailed
descriptions of major lithologic,. stratigraphic, structural; and geochemical subdivisions,
and accurate delineation of basin boundaries and major recharge areas. Suitable
numerical models of the ground-water flow system must be based on a conceptual
model that is a synthesis of this type of baseline information (Frenzel and Kaehler,
1990; Kernodle, 1992b). Such modeling efforts are-particularly important because of the
potential for saline-water encroachment and.land subsidence due to ground-water
withdrawals in some parts of the basin (Contaldo and Mueller, 1992; Kernodle, 1992a,
MacMiUan et al., 1976).
This report describes the results of a hydrogeologic study bythe New Mexico
Bureau of Mines and Mineral Resources (NMBMMR) of the Mesilla Basin and Vdey
fill between L a s Cruces, New Mexico and the International Boundary west of El Paso,
Texas (Fig. 1).The investigation, done in cooperation with the Water Resource Pivision
of the U.S. Geological Survey (USGS-WRD) and the New Mexico State Engineer
Office (NMSEO), was originally proposed (1986) because there needed to be better
utilization of hydrogeologic information in the management of the area's ground-vater
resources. The two major objectives of the study were (1) to provide a synthesis 04
available geological, geophysical and geochemical data that can be used to create a
detailed conceptual model of the basin's hydrogeologic framework, and (2) to conq?ruct
that model in a format suitable for use in developing the best possible numerical models
of the ground-water flow system.
Funding for the initial phase of data compilation and model development.iy 1987
was jointly provided by the NMBMMR and USGS-WRD, contract number 14.08-DOOlG-726; and subsequent support has been furnished by the N M l 3 " R . Intormation in
this open-file report will ultimately be integrated with geologic, geophysical, and
geochemical data from adjacent parts of the Jornada del Muerto Basin north and east
of Las Cruces. A final report on the area will then be published by the NMBMMR as
part of its Hydrologic Report series.
Background
The MesiUa Basin has thick fill deposits, locally as much as 3000 ft (915 m), that
are mostly unconsolidated and include the major fresh-water aquifers of the region. Of
particular importance, with respect to both water-supply and ground-water recharge, are
1
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EXPLANATION
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TEXAS
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Figure 1. Loation of study area.
I
widespread channel deposits of the modem and ancestral Rio Grande system tha.t are a
major component of the upper fXl sequence. A large body of subsurface geologic
information (e.g. borehole samples, geophysical logs, and geochemical data) has been
collected, particularly since 1980 when a significant increase in development of the
basin's ground-water resources was proposed by the City of El Paso. Prior to this study,
however, much of this information had not been analyzed or organized within the
framework of a conceptual model that accurately descnies the "architecture" of t asin
deposits with respect to the distribution of geological units that have distinct difEerences
in structural, lithostratigraphic, and hydrologic properties.
The model developed here has three basic components:
1. Structural and bedrock features include basin-bounding mountain upWs,
bedrock units beneath the basin SU, -faultzones within and at the edges of the
basin that influence sediment composition and thickness, and distribution of
igneous intrusive and extrusive (volcanic) rocks that penetrate, cap or are
interbedded with basin and valley fius.The locations-of major structural features
and bedrock units in the study area are shown on Plates 1-11,16 and 17. Fedrock
units, including volcanic rocks associated with upper Cenozoic basinand vt-illey
fills, are identified in Table 2.
2. Hydrostratigraphic units include major mappable subdivisions of the ba-in and
valley fill that are defined on the basis of genetic origin and age of a stratiyaphic
sequence of deposits (Table 1).Genetic classes include ancestral-river, recent
river-valley, basin-floor alluvial and playa-lake, and piedmont alluvial-fan
environments. Time-stratigraphic classes include units deposited during early,
middle and late stages of basin filling (lower, middle, and upper Santa Fe
Group); and deposits of the present Rio Grande (Mesilla) Valley system.
Distribution patterns of hydrostratigraphic units are shown on Plates 2-11, 16 and
17.
3. Lithofacies units are the fundamental building blocks of the model. Ten major
lithofacies subdivisions of the basin-filling sequence have been identified in this
study (Table 3). These units are mappable bodies that have distinctive
compositions, depositional and post-depositional environments, distribution
patterns, geophysical and geochemical properties, and hydrologic characteristics.
Dism%ution patterns of lithofacies units are also shown on Plates 16 and 17.
Previous Work on Basin Hydrogeology
The present Mesilla Basin study i s part of a more comprehensive investigat:on of
the hydrogeologic framework of southern Rio Grande rift basins initiated by the s-nior
author in 1962. Work was initially supported by the U.S. Soil Conservation Service
(SCS), Soil Survey Division in cooperation with the New Mexico State University
(NMSU) College of Agriculture (1962-1974) and subsequently funded by the
NMBMMR (Soil Survey Investigations-Desert Project). Early research emphasis wqs on
the influence of hydrogeologic factors on the genesis of desert soils, particularly on the
development of secondary carbonate, clay, silica, and gypsum accumulation in basin-fill
3
Table 1.
Key to informal hydrostratigraphic unitsin the Mesilla
Basin (Plates2 to 17, Tables3 and 4)
Unit
Description
Valley-Fill
RA
Deposits
-- Post
SantaFe Group
Riveralluvium;channelandfloodplaindepositsofinnerMesilla
Valley; as much as
100 ft thick. Map unit "Qvyf" of Seager et al.
(1987). Lithofacies subdivision Iv* is themajor hydrogeolo'3ic
component. Forms much of the "shallow aquifer" of Leggat et al.
( 1 9 6 2 ) , and "flood-plain alluvium" of Wilson et al. (1981).
Holocene to late
Pleistocene
VAValley-borderalluvium;tributaryarroyo(andthineolian)
deposits in areas bordering the inner Mesilla valley (river
floodplain), with locally extensive river-terrace deposits; as
(1987';
much as 140 ft thick. Map unit "Qva" of Seager et al.
Fillmore, Leasburg (Ft. Selden), Picacho, and Tortugas
morphostratigraphic units of Gile et al. (1981). Includes
lithofacies subdivisions Iv and
V. Most of unit is in
the
unsaturated (vadose) zone.
Holocene to middle
Pleistocene
Basin-Fill Deposits
--
Santa Fe Group
Rio Grande rift basin fill in New Mexico and adjacent parts of
Texas, Chihuahua (MEX) and Colorado. Includes alluvial, eolian,
and lacustrine deposits; with interbedded volcanic rocks (basalts
and silicic tuffs). In the Mesilla Basin area
the Santa Fe Group
may locally exceed2,500 ft in thickness. The groupcomprisw
four lithostratigraphic units- Hayner Ranch, Rincon Valley, Forc
Hancock, and Camp Rice Formations (Hawley et al., 1969; Seagnr et
al., 1987). It also includes the major aquifers of the area (King
et al., 1971; Wilson et al., 1981;
Hawley,.1984) and~issubdivided
into three informal hydrostratigraphic units:
USF Upper Santa
Fe Unit; coarse- to medium-grained deposits of tte
ancestral Rio Grande intertongue mountainward with piedmontalluvial (fan) facies, and southward with fine-grained lake and
playa sediments; volcanic rocks (mostly basalt) and sandy eolian
deposits are locally present; as much
as 750 ft thick.
Unit includes the Camp Rice (CR) and upper Fort Hancock
(FH)
Formations (Strain, 1966; Hawley, 1978; Gustavson, 1991); also
includes lithofacies subdivision Ib; much of facies
11, V, and VI;
and parts of facies I11 and VIII. Forms lower part of the
"shallow aquifer" in the northern Mesilla Valley, and the upper
aquifer zone outside the Valley area where much of the unit is
above the water table.
Middle
Pleistoceneto middle
4a
Pliocene
MSFMiddleSantaFeUnit;alluvial,eolian,andplaya-lakefacias;
interbedded sand and silt-clay basin-floorsediments intertcngue
mountainward with piedmont-alluvial (fan) deposits, and southward
with fine-grained lake and playa facies; basaltic volcanics and
sandy eolian sediments are locally present;
as much as 1500 ft
thick.
Unit includes basin fill that correlates with much of the Fort
Hancock (FH) and Rincon Valley Formations, whose type areas are in
the Hueco Bolson and western Jornada del Muerto (Rincon) Basin,
respectively; also includes much of lithofacies subdivisions 111,
and parts of facies 11, V, VI, VII, VI11 and IX. Forms major part
of "medium aquifer"
of Leggat et al. (1962).
Middle
Plioceneto middle
Miocene
LSFLowerSantaFeUnit;eolian,playa-lake,andalluvialfacies;
sandy to fine-grained basin-floor sediments, which include thick
dune sands and gypsiferous sandy mudstone, intertongue with
conglomeratic sandstones and mudstones near
the basin margins
(early-stage piedmont alluvium); as much 1000
as ft thick.
Unit includes basin fill that correlates with much of the Ha:mer
Ranch and the lower Rincon Valley Formations, whose type arens are
in thewestern Jornada del Muerto (Rincon) Basin; also includes
much of lithofacies IV and
X, and parts of facies VII, VI11 and
(1932).
IX. Forms major partof "deep aquifer" of Leggat et al.
Middle
Miocene
to
late
Oligocene
* Lithofacies subdivisionsof hydrogeologic units are defin,?d in
Table 3
4b
TABLE2
Key to bedrockunitsandupperCenozoicvolcanics
(Plates 2-17)
These rocks are
primariiy hydrogeologic boundary units with very low
hydraulic conductivities. However, limestones may locally
be highly permeable
in zones with solution-enlarged joints and fractures. Fractured sandsto?e,
conglomerate, welded tuffs, and lavas also form aquifers in a few areas.
QbBasalticvolcanics,mostlyflows,withlocalcinderconeand
interbedded with the
conduit material, that cap or are
middle Santa Fe Group. Quaternary and upperPliocene
upper
and
2b
Basalticplugsandminorflowsthatpenetrate,cap,
or are
interbedded with the lower and middle Santa
Fe Group. Miocexe
Tr
Rhyoliticvolcanics,withsomeinterbeddedsandstoneand
conglomerate mostly ashflow tuff and lava. Oligocene
Tri
Rhyoliticigneous-intrusivecomplexes;mostlysills,plugsand
associated lava domes. Oligocene
Ti
Silicic to intermediateintrusiverocks.
Tv
Andesiticandotherintermediate.volcanicandvolaniclasticrocks,
including lava flows and laharic breccias and mudstones. Eocene
and Oligocene
Tvi
Undivided Tv andintermediateintrusiverocks.
Tvs
Intermediatevolcaniclasticrocks,withminorlavaflowsand
intrusive units; primarily Palm Park Formation. Eocene and
Oligocene
Trv
Undivided Tr and
Tv
T1
Mudstone,sandstone,andconglomeratewithlocalgypsumbeds.
Lower Tertiary, mainly Eocene
T
V
l
Undivided
and
Tv
T1
K
Cretaceous rocks--undivided;.includes limestone,
.sands,tone.ard
mudstone.
TK
Undivided
Ti,
Tv,
T1,
KP
Undivided
Cretaceous
and
Permian
rocks.
PU
UpperPaleozoicrocks(PennsylvanianandPermian);includes
limestone, shale, sandstone, and mudstone, with local gypsum beds.
P
Undivided Paleozoic and Precambrian rocks
of the southern Franklin
Mountains; includes limestone, shale, sandstone, metamorphosEd
sedimentary and volcanic rocks, and granite.
.Oligocene andEocene
or Tvs
K.
5
Table 3
L i t h o f a c i e s s u b d i v i s i a r r of k i n - and v a l l e y - f i l l and t h e i r occurrence i n r o c k - s t r a t i g r a l h i c and hydrostratigraphic rnits i n
t h e n e s i l l a Basin.
Rock-stratigraphic units
and c o r r e l a t i v e l i t h o f a c i e s
(Table 1 )
Informalhydrostratigraphicunits
end aquifer system
(Table 1)
Sard and g r a v e l , r i v e r - v a l l e y
and basin-floor fluvial facies; recent
and
ancestral Rio Grade channel and floodplain deposits underlying 1) the nxrdern
river-valleyfloor--faciesIv,
2) r i v e r - t e r r a c e s u r f a c e s - . d e p o s i t s p r i m a r i l y i n
t h e vadose zone, a n d 3 ) r e l i c t o r b u r i e d b a s i n - f l o o r f l u v i a l p l a i n s - - f a c i e s
Ib.
The l a t t e r surfacesincludethe
La Mesa g e m r p h i c s u r f a c e ( G i l e e t a l . 1981).
Gravel is characterized by sub-rounded t o w e l l - r o u r d e d pebbles and smallcobbles
of resistant rock types (mainly
ign,eous a r d metamorphic) derived i n p a r t from
extra-basin source areas.
-
1v. sand and pebble t o cobblegravel, with thin, o r g a n i c - r i c h s i l t y sand t o
s i l t y c l a y lenses; indurated zones ofcarbonatecementationrareor
absent; as
rmch as 100 feetthick.
Younger v a l l e y f i l l , r i v e r f l o o d p l a i n and ChaMel
deposits
River alluvim,
aquifer system
Ib. Sand and pebblegravel,withthindiscontinuous
beds and lensesof
sandstone, s i l t y sard, a n d s i l t y clay; extensive basin-floor fluvial facies;
usuallynonindurated, but with l o c a l zones that are cemented w i t h c a l c i t e
( c m n ) , and otherminerels ( u n c m n ) i n c l u d i n g s i l i c a t e clays, iron-manganese
oxides, gypsun, s i l i c a , and zeolites; 200 t o 400 f e e t t h i c k i n central basin
areas.
Major component of the Camp
Rice Fm (Upper Santa Fe
G r q ) ; intertongueswith
facies 1 1 , I l l , V, and l o c a l l y
IX
Major component of w r Santa Fe
hydrostratiqraohic unit; mostly i n
vadose zone i n b a s i n areas outside the
Mesilla Vallev: occurs i n lower D a r t
o f shallow a&fer
system i n northern
Mesilla Valley; and forms part of the
w r aquifer system outside the
valley.
Sand, withdiscontinuous beds and lensesofpebbly
sand, s i l t y s a d , sandstone,
and l o c a l e o l i a n
s i l t y c l a y , and nuistone; extensive basin-floor fluvial facies
as i n facies I; usuallynonindurated, but l o c a l
deposits;gravelcarposition
cemented zones as i n facies Ib; clean sand and pebbly-sandbodies make up an
estimated 65-85 percentof unit; 300 t o 750 feet thick i n central basin areas.
Major component of Camp Rice
Formation, and present i n the
Fort Hancock Fm (Middle t o
Upper Santa Fe Group) i n the
M e s i l l a Basin; intertongues
withfacies Ib, 1 1 1 , V, and
locally I X
Major conponent o f u w e r Santa Fe
of
Interbedded sard, s i l t y s a d , s i l t y clay, and sandstone; withminorlenses
pebbly sand and conslaneretic sandstone; b a s i n - f l o o r a l l u v i a l and playa-lake
facies; clay mineralogy of
s i l t y c l a y beds as i n unit IX; usually nonindurated,
but withLocal cementedzones as i n f a c i e s I b and 11; secondarycarbonate and
gypsunsegregations locally present i n s i l t y c l a y beds; cunnon s h e e t - l i k e t o
b r o a d l y - l e n t i c u l a r s t r a t a 10 t o 40 feet thick: clean
sard layers make up en
estimated 35 t o 65 percentof unit; 300 t o 1,000 feet thick i n central basin
areas.
MajorccxpmentofFort
Hancock Formation, and present
i n the Carrp Rice Formation;
11,
intertongueswithfacies
V, I X , and Locally Ib.
Major component ofmiddle Santa Fe
hydrostratigraphic unit, and minor
constituent of u n i t umer Santa Fe:
s a d , pebbly sand a n d ' b i l t y sand beds'
i n facles I 1 1 form a major p a r t ofthe
medial aquifer system.
sand t o s i l t y sand, with Lenses ordiscontinuous beds o f sandstone, s i l t y c l a y ,
and mudstone; e o l i a n and a l l u v i a l f a c i e s p r i m a r i l y d e p o s i t e d
on b a s i n f l o o r s a r d
Major canpOnent o f unnamed
formation i n the Lower Santa
Fe Group; probably correlative
with parts of the
Rincon
Valley and Hayner Ranch
Formations i n northern Dona
Ana County; intertongueswith
facies V I 1 s r d X
Majorcmponent o f lower Santa Fe
hydrostratigraphic unit; sand and
s i l t y sand beds i n facies I V form a
large part of a deeo a q u i f e r system.
contiguous piedmont slopes; nonindurated t o p a r t l y i n d u r a t e d , w i t h
cementing
agents including c a l c i t e ( c m n ) , s i l i c a t e clays, iron-manganese oxides,
gypsm, a n d z e o l i t e s ( u n c m o n ) ; c l e a n f i n e
t o mediun sand makes up an estimated
35 t o 65 percentof unit; as much as 600 feet thick.
upper part of
hydrostratiqraphic unit; p a r t l y i n
vadose z m e i n basin areas outside the
MesillaValley;occurs
i n lower p a r t
of shallow aquifer system i n northern
MesillaValley; forms p a r t s of the
uooer and medial aquifer system
throughout the basin.
~~~
~~
~~
~~
~
~~~
~
~
V.
Gravelly sand-silt-clay mixtures (loamy sands t o sandy c l a y l o a m )
i n t e r s t r a t i f i e d w i t h i n d i s c o n t i n u o u s beds and Lenses o f sand, gravel, loamy sand
an s i l t y c l a y ; d i s t a l t o m e d i a l p i e c h n t - s l o p e a l l w i a l f a c i e s ( m a i n l y
coaleascentfandeposits),withminor
cOmpOonent o f e o l i a n sediments; gravel
primarily i n the pebble and small cobble size range, and clast composition
r e f l e c t s c h a r a c t e r o f sourcebedrockterrane;
u s u a l l y nonindurated, but with
t h i n discontinuouslayers t h a t are cemented w i t h c a l c i t e ; clean sand and gravel
makes up an estimated 25 t o 35 percentof unit; as rmch as 600 f e e t thick.
Major conponent o f Camp Rice
and F o r t Hancock Formations;
intertongueswithfacies
11,
Ill, V
I
, and I X
Component of both u m r and middle
Santa Fe hydrostratigradlic units;
c l e a n t o Loamy sand and gravel lenses
i n facies V form parts of the
and m e r a o u i f e r systems.
VI.
Coarse gravelly sand-silt-clay mixtures (loamy sard and sandy l o a m t o l o a m )
i n t e r s t r a t i f i e d w i t h lensesofsand
and gravel; proximal t o medial pi-nts l o p e a l l u v i a l f a c i e s - - f a n and coalescent fan deposits; gravel primarily
i n the
pebble t o cobblerange (up t o 10 inches); c l a s t c o m p o s i t i o n r e f l e c t s l i t h o l o g i c
character of source bedrockterranes;usuallynonindurated,
but with
discontinuous layers that are
cemented with calcite; clean
sand and gravel
Lenses make an estimated 15 t o 25 percent of unit; as rmch as 300 feet thick.
Cmpcnent of Cerrp Rice and
F o r t Hancock Formations;
intertongues with facies
V and
CompMent of both u m r and middle
Santa Fe h v d r o s t r a t i g r a h i c u n i t s ;
clean sand and gravel Lenses i n facies
V I form parts o f themedial and upper
aquifer system.
C o n g l m r a t i c sandstone, s i l t y sandstone. and mudstone with Lenses and
discontinuous beds of conglomrate, sand, gravel, and g r a v e l l y s a n d - s i l t - c l e y
mixtures(as i n unit V); d i s t a l t o medialpi-nt-slope
a l l u v i a l f a c i e s , with
minor ccmpnent of eolian
sediments;coarse clast sizes and canposition as i n
unit V; moderately-welltopoorlyindurated;
cementingagents i n c l u d e c a l c i t e
(cwrmon) and s i l i c a t e c l a y s , iron-manganese oxides, s i l i c a and z e o l i t e s
( u m m n ) ; cleanueakly-cementedsard
and gravel beds make up an estimated 5 t o
15 percent of unit;
as much as 600 feet t h i c k .
Majorconponent of unnamed
formation i n lower p a r t of
S m t a FeGroup;
probably
c o r r e l a t i v e w i t h piedmont
facies of the Rincon Valley
and HaynerRanch Formations;
intertongueswithfacies
IV,
VI11 and X .
Coarse c o n g l m r a t i c sandstoneand silty-sandstone, fanglomerate,
and minor
lenses of sard and gravel;proximal t o medialpiedmont-slope a l l w i a l f a c i e s - and coalescent fan deposits; coarse clast sires
and compositions as i n u
n
t
i VI;
moderately towellindurated;
cementingagents as i n unit VI; moderately t o w e l l
as i n u n i t VII; clean,weakly-cemented sand and
indurated;cementingagents
gravellenses make up an estimated 5 t o 10 percentofunit,
as nuch as 300 f e e t
thick.
Component of basal Camp Rice
and Fort Hancock Formations,
and m m e d formations i n
Lower p a r t ofSanta Fe G r O U p
(as i n u n i t s V I 1 and IV);
intertongueswithfacies
V, V I
and V I 1
Minor component o f a l l three
hvdrostratiarachicunits;neaklycemented sand and gravel beds i n
facies VI11 form small parts. of the
m r . m e d i a l and deep aquifer
I' X
beds;
Silty clay interbedded uith thin silty
sand, s a d , sandstone, and &stone
b a s i n - f l o o r p l a y a - l a k e and a l l w i a l - f l a t facies; clay mineral
assemblage
includes c a l c i m s m e c t i t e , m i x e d l a y e r i l l i t e - s m e c t i t e i l l i t e ,
and k a o l i n i t e
(Anderholm, 1985); secondary depositsofcalcite,
gypsun, sodiun-magnesiuns u l f a t e s a l t s , and zeolites are locally present;
weakly-cemented f i n e t o m e d i m
as nuch as 600
sand and s i l t y sand makes up an estimated 5-10 percent of unit;
f e e t t h i c k i n central basin areas.
Major component of the Fort
Hanckco Formation and l o c a l l y
present i n the Carrp Rice
Formation; intertongueswith
facies I l l , 1 1 , V, and l o c a l l y
Ib; gradesdounuard i n t o unit
X i n central basin areas
Makes up fine-grained part of middle
Santa Fe h y d r o s t r a t i g r a r h i c unit; sard
and s i l t y sand beds i n facies I X form
very minor t o n e g l i g i b l e component o f
the m e d i a l aquifer system.
X.
Mudstone and c l a y s t o n e i n t e r s t r a t i f i e d u i t h t h i n sandstone and s i l t y sandstone
beds; b a s i n f l o o r p l a y a - l a k e and a l l u v i a l - f l a t f a c i e s ; c l a y m i n e r a l
a n d non-clay
secondary mineral assemblages as i n facies IX; weakly cemented f i n e t o m e d i m
sard and s i l t y sand makes up an estimated 0 t o 5 percent of unit;
as nwch as 600
feet thick i n central basin area.
Major component o f unnamed
formation i n lower p a r t ofthe
Santa Fe Group; probably
correlative uith basin-floor
facies of the
Rincon Valley
and HavnerRanch Formstions:
IV'
intertbngueswithfacies
and VI1
Major component o f lower Santa Fe
hydrostratiarahicunit;ueaklycemented sand a n d s i l t y sand beds i n
facies X form very minor t o n e g l i g i b l e
coolponent o f deep aquifer system.
VII.
VIII.
Vlll.
aquifer system.
-
systems.
deposits. This work included geological loggingof commercial and domestic wate.r wells
being drilled in the Mesilla and Jornada del Muerto Basins, and developing a water-well
database that ultimately could be used to update existing ground-water reports by Sayre
and Livingston (1945), Conover (1954), Knowles and Kennedy (1958), and Leggat et al.
(1962); and complement ongoing studies by the City of El Paso (Cliett, 1969). Re.ports
summarizing stratigraphic and geomorphic aspects of this research were published in
1969 (Hawley; Hawley and Kottlowski, Hawley et al.).
In 1965, a formal study of geology and groundwater resources of central and
western Dofia Ana County was initiated by the NMSU Earth Science Department in
cooperation with the SCS and funded by the New Mexico Water Resources Research
Institute and the U.S. Department of Agriculture. W. E. King was Principal Investigator
and Hawley was responsible for geological-aspectsof the research. -This study was
completed in 1968 and published by the NMWRRI and NMBMMR (King et al., 1971).
A threefold division of basin-fill aquifers into lower;.intermediate (medium);and upper
(shallow) zones, oiiginally proposed by Leggat and others (1962) and Cliett (1969) was
recognized as being characteristic of lithofacies distribution.patterns that are widespread
in the Santa Fe Group, at least in the southeastern Mesilla Basin.
These early investigations demonstrated the need for a much more
comprehensive and quantitative evaluation of the area's water resources. In 1972, the
USGS-Water Resources Division established a field office in Las Cruces and initiated
ground-water investigations under the direction of C. A. Wilson. The results of this
major continuing effort, now headed by R. G. Myers, have been published by the
NMSEO and the USGS (Wilson et al., 1981; Wilson and White, 1984; Myers and Orr,
1985; Nickerson, 1986,1989; Frenzel and Kaehler, 1990).
After the untimely death of Clyde Wilson in 1980, a new effort on integratkg all
available subsurface geological and geophysical data on the Mesilla and southern
Jornada Basins was initiated by Hawley, now Senior Environmental Geologist with the
NMBMMR. This work was primarily funded by the Bureau of Mines and partly
supported by the NMWRRI through a grant to the New Mexico Tech Geoscience.
Department (Dr. Raz Khaleel, P.I.). A set of 17 hydrogeologic sections (
Ixand 1Ox
vertical exaggeration) and a map (1:125,000) showing major boundaIy faults were
prepared for that study and published as an appendix to a WRRI report by Peterson,
Khaleel, and Hawley (1984) on "Quasi Three-Dimensional Modeling of Ground Vater
Flow in the Mesilla Bolson, New Mexico." The hydrogeologic sections and base map
were also published as NMBMMR Open-File Report 190, which is included in th"
present report as Appendix B. The provisional 10-unit classification of lithofacies
distribution in basin and valley %i and the hydrogeologic cross sections developed for
the 1984 study have been used in the present investigation; but they have been modified
considerably (compare Appendix B and Plates 1, 16 and 17).
Continued research on basin hydrogeology also included cooperation with staff
and graduate students at NMSU and the University of Texas System working in the
areas of geology and geophysics, and with L. H. Gile ( S C S soil scientist-retired) on
Desert Project soil-geomorphology studies. Syntheses of geologic and geophysical
"
7
aspects of these studies are published as Geologic Maps 53 and 57 (Seager et al., 1982,
1987) of the New Mexico Bureau of Mines and Mineral Resources. Desert Project
research publications include Bureau Memoir 39 (Gile et al., 198l), and Gile (1S87,
1989). Research reports and graduate theses have been completed by Figuers (1587)
Gross and Iceman (1983), Mack (1985), Snyder (1985), VanderhiU (1986), and Ven
(1983). Related work on siting of future radioactive-waste disposal facilities has also
been done under contract with the US.Geological Survey, Basin and Range Working
Group (Bedinger et al., 1989). This study included preparation of hydrogeologic sections
of basins and ranges in the Mesilla-Hueco Bolson area of New Mexico and westcrn
Texas.
Methods and Techniques
Data Collection and Analysis
The initial step of the 1987 investigation was to collect and review all pertinent
geologic and hydrologic information on the Mesilla Basin. This was done in order to
develop a comprehensive database from which the hydrogeologic framework was
constructed. Much of this information had already been collected for the earlier
modeling study by New Mexico.Tech (Appendix B; Nawley, 1984; Peterson et al., 1984).
Key sources of surface and borehole data were identified and located on base maps of
the Mesilla Basin (scales 1:24,000 and 1:100,000) for use as control points. These data
include borehole cuttings and geophysical logs, geothermal and geochemical repods,
and geologic maps. Six water-test wells drilled by the USGS and the City of El P-<.soas
part of this study provided supplemental information. The Afton, Lanark, La Unitm,
and Noria test wells (MT 1 to 4) were drilled in the basin area west of Mesilla Valley
(La Mesa surface). The other two wells (CWFlD and 4D; Nickerson, 1987, 1989) are
located in the CanutiUo Well Field area on the Rio Grande floodplain west of Vinton,
Texas. Subsurface data were supplemented by detailed seismic.reflection profiles made
at two sites near the Canutillo Well Field (C. B. Reynolds and Associates, 1986, 1987).
Drill Cuning and 7% Section AnaIysis
Cuttings from the Afton, Lanark, La Union, and Noria test wells (MT 1 to 4)
were initially analyzed with a binocular microscope in order to construct a geologic log
for each well and to determine sample intervals for thin section work. No preliminary
cutting analysis was performed on samples from the Canutillo Field (CWFlD and
CWF4D) because these wells were drilled very late in the study. Color, grain size, and
other major characteristics of the sediments were noted on the geologic logs. Cutt'ngs
were analyzed in approximate 10 ft (3 m) intervals. Geophysical and driller logs aided in
the initial examination of the cuttings.
Based on the cutting analysis, samples for thin section study were collected at
approximately 100 ft (30 m) intervals from representative sand beds in the Afton,
Lanark, La Union, and Noria wells. Samples were also collected from sandy intervals
within the CWFlD and CWF4D wells, and from Santa Fe Group outcrops in the area.
Locations of sampled wells and outcrops are shown on Plate 1. Forty-six thin sectilms
8
were analyzed using criteria described by Dickinson (1970) in order to determine
detrital modes and provenance. Thin-section petrographic data and interpretatiors are
presented in Section 111 and Appendix A. Four hundred framework grains per thin
section were point counted using a petrographic microscope. Ternary diagrams were
constructed based on the point counts and data were also plotted on the geologic.petrographic logs of the Afton, Lanark, la Union and Noria Test Wells (Plates 12-15).
Digitizing Borehole Geophysical Logs
Concurrently with the cutting and petrographic analysis, borehole geophyskal
data from selected key wells were digitized and then plotted onto computer-generated
worksheets with a basin cross-section format. The borehole data were plotted to an
altihide datum-of 4,500 ft (1372 m) above MSL(vertica1 scale 1 in = 100 ft, 1cm =
12.2 m). Digitizing of geophysical .logs,and plottingof :cross-sectionworksheets was .done
at the USGS-WRD District Office in Albuquerque. The ComputerLgenerated. graphics
system utilized in this study for.integrating geophysical, geologic.and -hydrologic data
(Plates 2-15) was developed by Ken Stevens; formerly with that office.
Hydrostratigraphic Unit Correlation and Hydrogeologic Framework
The basic approach of this investigation was the correlation of borehole-electric
(resistivity), geologic-petrographic, and driller logs. Plates 12-15 summarize this
information for the four test we& (W 1 to 4) drilled as part of this study in
representative areas of the central and southern parts of the basin. After detailed review
of geophysical and geologic-petrologic data, and supplemental geothermal and
geochemical information (Tables 4 to 6), initial correlations were made between these
key boreholes and other wells in the basin (Plate 1).Ken Stevens of the USGS-U'RD
and Francis West of the NMSEO collaborated in this phase of the study. Prelimirary
cross section plots based on analyses of these data were prepared and reviewed prior to
preparation.of ten representative-hydrogeologicsections of the basin. The sections, with
selected borehole geophysical and geochemical data, are illustrated in Plates 2 anll 11.
Plates 1, 16 and 17, with supporting data in Tables 1to 3, integrate the above
information into a conceptual model of the basin's hydrogeologic framework. The
model's base elevation is 1,000 ft (305 m) above mean sea level.
Well-Numbering Systems
Wells in New Mexico are identified by a-location-number system based on the
township-range system of subdividing public lands. The location number consists of four
segments separated by periods, corresponding to the township, range, section, and tract
within a section (Fig. 2a). The townships and ranges are numbered according to their
location relative to the New Mexico base line and the New Mexico principal meridian.
The smallest division, represented by the third digit of the final sequent, is a 10-acre (4
ha) tract. If a well has not been located precisely .enough to be placed within a
particular section or tract, a zero is used for that part of the location number.
Wells in Texas are officially given a well number consisting of five parts (F'g. 2b).
The first part is a two-letter prefix used to identify the county, with El Paso County
9
Figure h.Well numbering system: Diagram showing system of number& wells in New
Mexico.
10
LOCATION 'OF WELL
JL-49-04-501
49 1-degree quadrangle
04 71-minute quad-angle
5 24-minute quad-angle
01
Well number within 24-minute
quadrangle
JL Symbol
2
for El Paso County
13
21-minute quadrangles
Figure 2b. Well numbering systems: D&am
numbering wells in Texas.
showing system of
11
being represented by JL. The second part of the number has two digits indicating the 1degree quadrangle. Each 1-degree quadrangle is divided into 64 7%-minute quadrangles.
This is the third part of the well number. The first digit of the fourth part indicates the
2%-minute quadrangle, and the last two digits comprise a sequence number that
identifies the well from others in the same 2%-minute quadrangle. As an example (Fig.
2b), well JL-49-04-501 is in El Paso County (JL),in 1-degree quadrangle 49, in 7%minute quadrangle 04, in 2%-minute quadrangle 5, and was the first well invento.-ied in
this 2%-minute quadrangle.
Acknowledgments
Numerous individuals and organizations provided assistance during the course of
this study and earlier related investigations. Valuable contributions have been personally
made by a large number of the authors of cited references. Many of the basic concepts
on the area’s geology have been developed by F. E. Kottlowski and W. R. Seager. Other
important collaborators on geological and geophysical aspects of the study include R. E.
Clemons, L. H. Gile, Tom Gustavson, G. R. Keller, Shari Kelley, Greg and Pamela
Mack, Paul Morgan, C. B. Reynolds, Jay Snyder, W. S. Strain, and Jim Vanderhi’l.
The conceptual model of the basin’s hydrogeologic framework was developed
over a period of three decades in collaboration with Tom Cliett, W. E. King, Bob
Myers, Dave Peterson, Andrew Taylor, and the late Clyde Wilson. Ken Stevens,
formerly with the U.S. Geological Survey-Water Resources Division, Francis West. of
the New Mexico State Engineer Office, and Tom Cliett, formerly with the El Paso
Water Utilities Department, were the driving forces behind the present study; and they
played a key role in defining the geological, geophysical and geohydrologic eleme7ts
that are basic building blocks of the conceptual model. Special acknowledgment iq due
to Ken Stevens who developed the computer-generated graphics system used in tl is
study.
Logistical and financial assistance by the U.S. Geological Survey-Water
Resources Division (Albuquerque, Las Cruces and El Paso offices), El Paso Water
Utilities Department, Elephant Butte Irrigation District, International Boundary
Commission, New Mexico Bureau of Mines and Mineral Resources, New Mexico State
Engineer Office, and New Mexico Water Resources Research Institute is gratefury
acknowledged. Bob Myers, Ed Nickerson and Don White of the USGS Las Cruces and
El Paso offices have been particularly helpful, as have Peter Frenzel, Charles Haywood,
and Mike Kemodle of the USGS Albuquerque office.
This report is dedicated to the memory of Clyde k Wilson, who headed the
USGS-WRD office in Las Cruces from 1971 until his untimely death in 1980. Clyde was
an unassuming and highly motivated public servant who played a key role in putti2g
ground-water hydrology and hydrogeology of the Mesilla Bolson area on a sound
technical and scientific footing. His expertise and common-sense approach to watcrresource investigations are greatly missed.
12
11: GEOLOGIC SETIWG OF THE MESILLA BASIN
Introduction
The Mesilla Basin (Figs. 1 and 3) is at the southern end of a north-trending
series of structural basins and flanking mountain uplifts that comprise the Rio G-ande
rift (Chapin and Seager, 1975; Seager and Morgan, 1979; Chapin, 1988). The rift
extends through New Mexico from the San Luis Basin of south-central Colorado to the
Hueco Bolson and Bolson de 10s Muertos area of western Texas and northern
Chihuahua (Hawley, 1978). The rifting process began in Oligocene time, about 25 to 30
million years ago (Ma), and is continuing at present. During this long intervab
extensional forces have stretched the earth's crust, causing large basin blocks to rqtate
and sink relative to adjacent mountain uplifts. All rift basin fill that was deposited prior
to formation of the Rio Grande Valley in the .early to middle Pleistocene (1.7 to 0.7
Ma) is included in the Santa Fe Group (Bryan, 1938; Spiegel and Baldwin, 1963;
Hawley et al., 1969; Hawley, 1978; Chapin, 1988).
The upper Rio Grande now flows southward through a series of valleys cut along
the deeper parts of most of the riftbasins as far as El Paso. Beyond the Paso del Norte
gap (El Paso "Narrows"between the Franklin .and Juarez uplifts, Fig. 1) at the so-lthern
end of the Mesilla Basin, the river flows southeastward down the Hueco Bolson exis
along the International Boundary . toward the Big Bend area of Trans-Pecos Texa9.
Intermontane-basin and river-valley tills of the Rio Grande rift comprise the major
aquifer systems of the region and are the principal subject of this report.
The Mesilla Basin, covering an area of about 1,000 sq mi(2590 km?, is in the
southeastern part of the Basin and Range physiographic province (Fig. 3; Hawley,. 1986).
It extends southward about 60 mi (100 km) from the upper Mesilla Valley betwee.n the
Robledo and Doiia Ana Mountains to a poorly defined ground-water divide near the
International Boundary west of El Paso and Ciudad Juarez. Basin width varies from
about 5 mi (8 km) at its northern end to about 25 mi (40 km) in its central part.
Flanking mountain uplifts (Juarez-Franklin-southernOrgan on the east and East
Potrillo-Robledo on the west; Plate 1)are narrow and relatively low-lying (less than
8,000 ft, 2440 m, elev.) in comparison with ranges of the northern and central Rir
Grande rift (Hawley, 1978).
Broad plains with low topographic relief (less than 500 ft, 150 m) .characterize
much of the basin area (Hawley, 1975; Gile et al., 1981). The single major erosioral
feature is the broad Mesilla Valley of the Rio Grande located on the east side of the
basin (Fig. 1). An extensive remnant of the,basin-floor surface that predates river-valley
incision is preserved between the Mesilla Valley and the East Potrillo and Robledo
uplifts. This geomorphic surface is called "La Mesa" in many earlier reports on the area
(Conover, 1953; King et al., 1971; Gile et al., 1981) but is simply designated the "West
Mesa" in recent water resources publications (Wilson et al., 1981; Myers and Orr, 1986).
Basin Structure and Bedrock Units
The internal structure of Mesilla Basin is complex (Figs. 3 and 4, Plates 1, 16,
and 17). Structural interpretations in this report are based on oil and geothermal testwell, water-well, and both surface and borehole geophysical data (Plates 2-15, Table 4).
13
C
I
-
--
10
-
20mi
10
I
4LLL Fault-hatchures on
downthrown sidqdashed
where inferred or buried
Cross section
20km
Figure 3. Index map of Mesilla Basin area showing locations of
major boundary and intrabasin faults, adjacent mountain
uplifts, and geologic cross sections (Fig. 4).
14
W
n
Figure 4. Diagrammatic geologic cross sections of the northern
and central Mesilla basin.
15
The major structural elements include three large subbasins (eastern, southwestern,
northwestern), with general north-south trends, a buried mid-basin uplift, and an
inferred south-central basin that extends into Chihuahua west of the Cristo Rey (Sierra
Juarez) uplift- The northeastern boundary of the Mesilla Basin is formed by a pa-tlyburied bedrock ridge, designated the Doiia Ana-Tortugas uplift on Plate 1.
Topographically, the basin merges northward with the Jornada del Muerto Basin,
northeast of Las Cruces, and southward with the Bolson de Los Muertos plains,
southwest of El Paso-Ciudad Juarez (Figs. 1 and 3).
AU boundaries between the major subbasins and flanking uplifts appear to be
formed by zones of high-angle normal faults. Many of the exposed mountain blocks are
strongly tilted, and at least some of the basin blocks have a tilted half-graben
morphology and listric boundary faults that.are.typica1 of most continental rift baqins
(Rosendahl, 1987; Seager, 1989; in press; Seager et al., 1984; 1987). Dips are usually
very low in the central basin area, however; and the major subbasins and intrabash
uplifts are here interpreted as only slightly tilted graben and horst blocks which a-e
bounded by high-angle normal faults that may or may not flatten signiscantly with
depth (Fig. 4, Plates 16 and 17).
Basin subsidence was initiated in late Oligocene time, but maximum differential
displacement between the major basin and range structural blocks probably occur-ed
between 4 and 10 million years ago (late Miocene to early Pliocene). By late Mio:ene
time rock debris eroded from adjacent highlands, and possiblyfrom adjacent parts of
the Rio Grande rift, had filled existing subbasins (mostly half grabens) to the point
where intrabasin uplifts (horsts) were buried by lower and middle Santa Fe Group
deposits. The broad topographic basin formed by this infilling process continued t?
aggrade as a single (upper Santa Fe) unit through the early middle Pleistocene when
widespread basin filling ceased due to entrenchment of the Rio Grande Valley system.
The thickest Santa Fe Group fills in the Mesilla Basin (about 3000 ft, 900 m) are
located in areas adjacent to themost active segments of major boundary fault
zones-the Mesilla Valley, East Potrillo, and East Robledo (Figs. 3 and 4, Plates 16 and
17).
Bedrock Units of Basin-Margin UpIifts
The Mesilla Basin, in contrast to many basins of the northern and central Rio
Grande rift, is not bounded by continuous ranges of high mountains (Hawley, 1978;
Chapin, 1988). Onlap of basin fill has buried most of the Doiia Ana-Tortugas and
southern Organ-Bishop Cap uplifts on the northeastern basin margin, and the East
Potrillo and Robledo uplifts to the west. Only the Franklin and Juarez uplifts at the
basin’s southeastern edge form well-exposed structural highlands (Fig. 1).
Tertiary igneous intrusives (granites to monzonites) and volcanics (rhyolites to
andesites) are the dominant rocks exposed in the Dofia Ana and southern Organ
Mountains (Seager et al., 1976; Seager, 1981). Marine sedimentq rocks, mainly
carbonate types, of Paleozoic and early Cretaceous age are the dominant lithologic units
exposed in the Tortugas, Bishop Cap, Franklin, Juarez, East PotriUo, and Robledo
uplifts (Harbour, 1972; Kelley and Matheny, 1983; LeMone and Lovejoy, 1976; Lovejoy,
16
1979; Seager et al., 1987; Seager and Mack, in press). A variety of sedimentary a l d
intermediate-intrusive rocks of Cretaceous and early Tertiary age crop out in the Paso
del Norte area between Franklin Mountains and Sierra de Juarez, which includes Cerro
de Cristo Rey on the Chihuahua-New Mexico border (Fig. 1; Lovejoy, 1976).
Middle Tertiary volcanic and intrusive rocks of intermediate to silicic composition
are exposed in isolated upland areas such as the Sleeping Lady and Aden W s in the
western part of the Robledo uplift, and Mount Riley northwest of the East Potrillo
Mountains (Fig. 1; Seager, in press).
No additional information on the configuration of the basin's buried northeastern
boundary (Doiia Ana-Tortugas-Bishop Cap trend) was collected during the presext
study. Provisional interpretations in Hawley (1984; Appendix B, Plate H-H) will be
revised in a future report after surface geophysical surveys and test driUing programs in
that area have been completed by the U.S. Geological Survey.
Bedrock Units Beneath the Basin Fill
Analyses of drill cuttings and geophysical logs from a few deep test wells (oil and
gas, water, and geothermal), and surface ,geophysical surveys are the only sources of
information on the lithologic character and structure of bedrock units beneath the riftbasin fill. Oil and gas test holes descnied by Seager and others (1987), including wells
25.1.32.141 and 26.1.35.333 in the central part of the basin (this report), encountered a
thick sequence of lower to middle Tertiary volcanics and, lower Tertiary sedimentary
rocks. The latter unit of continental origin was deposited in deep, northwest-trenc'ing
basins of Laramide age (Seager et al., 1986). The lower Tertiary section is only erposed
in a few places along the northern and eastern basin margins (Seager et al., 198r.
Cretaceous and upper Paleozoic underlie the middle to lower Cenozoic sequence at
great depth in most parts of the basin; but Cenozoic units may rest directly on lover
Paleozoic or Precambrian rocks in a few areas (Seager 1989; Seager et al., 1986).
All deep test drilling to date indicates that lower to middle Tertiary volcanic and
volcaniclastic rocks of intermediate to silicic composition are the dominant units tllat
immediately underlie Santa Fe Group basin till..Besides the previously mentioned oil
tests, water test wells that have definitely penetrated these units include wells24.1.8.123,
25.1.6.333, and 27.1.4.121 in the central part of the basin, and wells 24.2.4.334,
29.3.2.243, and 49-04-109 east of the Mesilla Valley faukzone near the east edge of the
basin (Plates 1,16 and 17).
Basin-Fill Stratigraphy
Middle and upper Cenozoic sedimentary deposits of the Rio Grande rift can be
subdivided into two major units: 1) Santa Fe Group basin fill of late Oligocene to
middle Pleistocene age, and 2) post-Santa Fe, river-valley and basin deposits of m'ddle
and late Quaternary age. These sediments are locally interbedded with and capped by
basalt and andesite flows and pyroclastic (vent) deposits. Associated with these extrusive
rocks are intrusive bodies that include feeder dikes, plugs, sills and breccia pipes. Dated
basalts in the southwestern New Mexico region include scattered occurrences of middle
Miocene to Pliocene age and extensive lava fields of Quaternary age. Pleistocene basalt
17
flows and associated vent units (e.g. cinder cones, lava shields, and maars) form a
widespread cover on the upper Santa Fe Group in the west-central Mesilla Basin area,
and they also cap large parts of the southern Robledo and East Potrillo uplifts (ITQffer,
1976; Seager et al., 1987; Seager, 1989, in press). Basaltic andesites
of late Oligocene
age, which are interbedded with lower Santa Fe beds and extensively exposed the. Sierra
de Las Uvas area of northwestern Dofia Ana County (Fig. l),may be present in the
basal part of the Mesilla Basin fill.
Volcanic layers of basaltic to andesitic composition have been reported in drilling
records of two water wells in the northern basin area including the Mesilla ValleJr near
Las Cruces (24.1.13.411) and may be either flows of siUs interbedded with or intruded
into the basin fill. A new well drilled at the Las Cruces waste-water treatment plant
(about 1.5 mi, 2.4 lan, WSW of.23.1.13.411) reportedly,encountered a basalt layer at a
depth of about 880 ft (270 m) in the middle to lower part of the basin-fill section (R. G.
Myers, oral communication 7-14-92).
Santa Fe Group
The Santa Fe Group (Spiegel and Baldwin, 1963; Hawley et al., 1969; Chapin,
1988) is the major fill component of Rio Grande rift basins. In southern New Mexico
and western Trans-Pews Texas the Group ranges in age from about 25 to 0.7 Ma and
inchdes alluvium derived from adjacent structural uplifts and nearby rift-basin areas,
and locally thick eolian and playa-lake sediments. Fill thickness in most of the central
basin area (between the Mesilla Valley and East Potrillo-Robledo fault zones) ranges
from 1,500 to 2,500 ft (460-760 m). In this report, the Santa Fe Group is subdivid-d into
informal lower, middle and. upper lithostratigraphic units defined on the basis of general
lithologic character,' depositional environments, anddiagenetic features related to age
and post-depositional history. Generally-equivalent hydrostratigraphic units are
discussed in Section IV.
The lower Santa Fe Group is dominated fine-grained basin floor sediments that
intertongue with alluvial fan deposits beneath the distal piedmont slopes that border
adjacent mountain uplifts. Sandy eolian sediments locally form thick sheets and lenses
that are interbedded with both basin-floor and .piedmont-slope deposits. Buried dune
complexes as much as 500 ft (150 m) thick have been identified beneath the Mesilla
Valley in the Anthony-Canutillo area (Cliett, ,1969; Hawley, 1984) and are probably
preserved in other parts of the eastern (LaUnion-Mesquite) subbasin (Plate 1).P i c k
eolian deposits possibly also occur in the deeper parts of the southwestern subbasin east
of the East Potrillo fault zone.
Lower Santa Fe beds probably range in age from 25 to 10 Ma and were de3osited
in a closed-basin setting prior to the final interval of deep basin subsidence and
of
the higher flanking range blocks (e.g. Organ, Franklin, East Potrillo, and Robledc
Mountains). Formal lithostratigraphic subdivisions of the lower Santa Fe Group have
not yet been proposed for the Mesilla Basin. However, the unit is generally correlative
with the Hayner Ranch Formation and the lower part of the Rincon Valley Formltion
mapped in the Jornada del Muerto-Rincon Valley area of northern Dofia Ana Ccunty
(Seager and Hawley, 1973; Seager et al., 1971, 1982, 1987).
.lift
18
The middle Santa Fe Group was deposited between about 10 and 4 Ma when rift
tectonism was most active and deposition in subbasins adjacent to the major boundary
fault zones (Mesilla Valley, East Potrillo, East Robledo) was most rapid. In many areas
erosion of uplifted basin borders and deposition on adjacent piedmont slopes also
accelerated relative to early Santa Fe time. Rapidly aggrading central basin plain? were
characterized by broad alluvial flats that terminated in extensive playa l a k e s ; and, most
mid-basin uplifts are deeply buried by Middle Santa Fe deposits. Alternating bed: of
clean sand, silty sand, and silt-clay mixtures are the dominant lithofacies (Section:: LII
and IV) in much of the central basin area. Eolian sediments also continued to
accumulate in leeward (eastern) basin area; but the thickest buried dune sequences
appear to be confined to the bwer Santa Fe Group.
.Formal lithostratigraphic.subdivisiom.havenot yet been proposed; but the middle
Santa Fe unitprobably correlateswitkat least~theupper part
of the Rincon Valley
Formation (Seager et al., 1982, 1987) and-thelower Fort Hancock Formation, which has
a type area in the southeastern.Hueco Bolson (Strain, 1966; Hawley et al., 1969;
Gustavson,1991).
The upper Santa Fe Group contrastsmarkedly with older.Santa Fe units i n terms
of lithologic character. About 3 to 4 million. years ago, the floor of the Mesilla Bssin
was transformed from an internally-drained feature to the broad fluvial plain of a
throughgoing river. Braided distributary channels of the ancestral upper Rio Grarde
spread southward across the basin-floor and ultimately terminated in large playa-lake
plains in the Bolson de 10s Muertos of north-central Chihuahua and the southern
Tularosa Basin-Hueco Bolson area of New Mexico and western Texas (Hawley et al.,
1969, 1976; Hawley, 1975, 1981; Gile et al., 1981; Seager et al., 1984, 1987).
Sandy deposits.,ofthis complex fluvial-deltaic system continued to accumulate on
the Mesilla Basin floor through early Pleistocene time. Recent research on basin-fill
magnetostratigraphy panderhill, 1986; Mack et al., 1991) and dating of volcanic ash
lenses in the upper part of the Santa Fe sequence (Gile et al., 1981) demonstrate that
widespread fluvial aggradation of the Mesilla.Basin floor.(and Santa Fe Group
deposition) had ceased by about 0.7 Ma. By 0.6 Ma, significant incision of upstream and
downstream canyon areas (Selden and El Paso) had.already occurred; and
entrenchment of the Mesilla Valley by the ancestral Rio Grande had begun.
The uppermost part of the Santa Fe Group in the south-central New Mexico and
western Texas area, and the main upper Santa Fe component, is the Camp Rice
Formation of Strain (1966). It has now been.recognized and mapped in detail from the
southern Palomas and Jornada del Muerto Basins, across the Mesilla and souther?
Tularosa Basins, and throughout the Hueco Bolson to its type area near Fort Hancock
in Hudspeth County, Texas (Hawley et al., 1969; Seager et al., 1971, 1976, 1982, 1987;
Hawley, 1975, 1978; Gile et al., 1981; Gustavson, 1991). Camp Rice deposits are very
well preserved throughout most of the Mesilla Basin, with significant erosion only
occurring in the Mesilla Valley and valleys of a few major arroyos. The formation’s
thickness ranges from about 300 to 700 ft (90-215 m) in central basin areas.
The dominant lithofacies of the Camp Rice Formation is the complex of fluvial
sand and pebbly sand deposits laid down by the ancestral Rio Grande. However,
19
because of complex channel shifts (influenced by both tectonism and climatic factors) in
the ancestral river system during the long interval of basin-floor aggradation, &negrained (slack-water) facies are locally present. The other important Camp Rice
lithofacies is a piedmont-slope facies assemblage that is primarily composed of fax
alluvium and associated debris-flow deposits. To the south and southeast, the basal
Camp Rice of the Mesilla Basin area appears to intertongue with and overlap finegrained alluvial and playa-lake deposits of the upper Fort Hancock Formation of Strain
(1966). In their type areas near Fort Hancock in Hudspeth County, Texas, the Camp
Riceport Hancock Formation contact has been dated at about 2.5 Ma (Vanderhill,
1986; Gustavson, 1991).
Post Santa Fe Deposits
:Post-Santa Fe Group sedimentary units of middle and late Quaternary age were
deposited in two contrasting geomorphic settings: (1) valleys of the Rio Grande a7d
tributary arroyo system, and (2) extensive.intermontane-basin'areas still not integrated
with the river (Hawley and Kottlowski, 1969;Hawley, 1975; Gile.et al., 1981). Valley-€ill
units were deposited during repeated episodes of river incision separated .by intervals of
partial backIXing that produced the present ,landforms of the Mesilla Valley. The
stepped-sequence of geomorphic surfaces (mainly alluvial .terraces and fans) that border
the inner-valley (floodplain) area are mainly the product of valley-entrenchment
episodes during Pleistocene glacial (pluvial) stages, and subsequent intervals of vdley
aggradation during interglacial (pluvial) stages. The 60 to 100 ft (18-30 m) of mediumto coarse-grained alluvium beneath the modem river floodplain ("flood-plain alluvium"
of Frenzel and Kaehler,l990) is a product of (1) valley cutting by a high-energy fluvial
system during the late Wisconsinan .(full) glacial substage about 15 to 25 thousand years
ago p a ) , and (2) valley filling during the late-glacial and ongoing, Holocene inte-glacial
stage that started about 10 Ka. Tributary alluvial systems have delivered more sediment
to the valley floor than the river could transport out of the drainage basin during this
ongoing period of fluvial aggradation.
The shallow aquifer system in the Mesilla Valley is formed by (1) the saturated
part of the inner-valley SU, and (2) channel sands and gravels in underlying beds of the
upper Santa Fe Group that were deposited by the ancestral Rio Grande during .th e midto late Pliocene interval of basin filling. Older valley fills, of the tributary arroyo systems
as well as the ancestral river, that are preserved in terrace remnants on the valley
borders ("valley-border surfaces"), are generally above the water table and are not
descriied in this report. Thin (<30 ft, 10 m) alluvial, eolian, and playa-lake sediments
deposited in areas of the Mesilla Basin still not integrated with the Rio Grande a1e also
not discussed. They are included with the upper Santa Fe unit in the hydrogeologk cross
sections (Plates 2-11, 16-17) that are covered in Section Tv. Younger valley and b,-lsin
fills, and soil-geomorphic relationships are descriied in detail by Gile et al. (1981) and
Seager et al. (1987).
20
III: SAM)-FRACTION PETROGRAPHY
Introduction
Prior to the present study, no detailed geologic or geophysical informatior had
ever been collected from deep water test wells in the central and southern basin area
west of the Mesilla Valley. The four test wells drilled in 1986 for the U. S. Geological
Survey and the City of El Paso at the Afton, Lanark, La Union, and Noria sites (Plate
1, 25.1.6.333, 27.1.4.121, 27.2.13.331, and 28.1.34.414) were specifically designed to
provide baseline information on general basin fill lithology, sand-fraction petrography,
borehole geophysics, and ground-water quality at selected drill-stem sample intenals.
Because no core samples were taken, lithologic and petrographic analyses could cdy be
done on sets of drill-cuttings carefully collected at ten-foot intervals from these test
wells.
Sand-fraction petrographic interpretations described in this section have be.en
integrated with selected borehole lithologic and .geophysical.data . i n .four geologic
columns (Plates 12-15). These columns illustrate basic hydrogeologiccharacteristics of
basin-fill deposits in the area of the four.test.holes; and they demonstrate that
correlation of the major lithostratigraphic subdivisions of the Santa Fe Group (lover,
middle, upper) descriied in Section II-ispossible .throughout much ,of the Mesilla Basin.
The hydrostratigraphic units described in detail in Section I V , which generally
correspond to these basin-fill subdivisions, are also shown on Plates 12 through 15.
Supplemental analyses of sand-fraction petrography from two recent test holes in
the Canutillo Well Field (CWF 1D and 4D; JL-49-04-481; Nickerson, 1989) were also
done as part of this study. This is the area where Santa Fe Group basin fill was
originally subdivided into "lower, medium, and upper" aquifer zones by Leggat an1
others (1962; Cliett, 1969).
Methods and Techniques
Preliminary Drill-Cutting Analyses
Cuttings from the Afton, Lanark, La Union, and Noria test wells were analyzed
initially with a binocular microscope in order to construct a stratigraphic column for
each well and to determine intervals where subsamples of representative sands an4
sandstones would be collected for thin section analyses. Color, grain size, and,,otht:r
major characteristics of the sediments were noted on the.stratigraphic columns. Cuttings
were analyzed in approximate 10 ft (3 m) intervals. Geophysical and driller logs aided in
the initial analyses of the cuttings.
Thin Section Sample Collection and Preparation
Based on the cutting analysis, thin section samples were collected in approJimate
100 ft intervals from the above four wells. Samples were also collected from sandy
intervals penetrated by the Canutillo Well Field test holes (CWFlD and CWF4D). In
addition, samples from representative Santa Fe Group outcrops were collected to use as
a standard for comparison with the subsurface samples. Locations of sampled outcrops
are given in Appendix A.
21
Wherever possible, medium- to coarse-grained sand was sampled. Finer-grained
samples were used only when coarser samples were unavailable. Ingersoll et al. (1984)
have shown that sand grain size does not affect point counting results. Sand samFles
were sieved (2.0-0.125 mm) to collect only the sand fraction. To guard against po.sible
contamination, the sieved sand was re-examined with a binocular microscope to r5move
foreign material (i.e., wood, cement, seeds, drill bit shavings). Next, the sand samdes
were impregnated with epoxy and cut into standard thin sections. The final step i7 thin
section preparation was to stain half the thin section slide with sodium cobaltinitr3e to
facilitate potassium feldspar identification.
Thin Section AnaEys.6
Thin sections of the well cuttings and outcrop samples were analyzed using
criteria described by Dickinson (1970) in order to determine detrital modes and
provenance. Other workers (i.e., Mack, 1984; Lozinsky, 1987) have shown that point
counting is a powerful tool for analyzing Santa Fe Group deposits. A total of 46 thin
sections were examined; 37 from well cuttings and 9 from outcrops. Four hundred
framework grains per thin section were counted using a Nikon binocular polarizirg
microscope and a Swift digital point counter. Counts were primarily made at 100% but
other magnifications were sometimes used. Nicols were usually crossed, except fcr
occasional glances at plain light. Parameters counted and used to define petrofacies are
interstitial mace
listed on Table 5. Only framework grains were counted. Matrix and
were not counted because most samples were loosely consolidatedand broken apart in
the drilling process. After each point count, the thin section was further examine3 to
determine grain size, sorting, roundness, and other important features. Point comt
results are summarized in Table 6 and listed in Appendix A. Ternary diagrams (Figs. 57) were constructed based on the thin section point counts.
22
Table 5. Point-count grain parameters. Modified from Dickinson
(1970)
Counted
rmrameters
Qm = monocrystalline quartz
Qpt = tectonic polycrystalline quarts
Qpn = nontectonic polycrystalline quartz (inc. chert)
P = plagioclase feldspar
K = potassium feldspar
Lv = volcanic lithic fragments
Lm = metamorphic lithic fragments
Ls = sedimentary lithic fragments (silt and shale)
LC = carbonate lithic fragments
M = phyllosilicates
Reaalaulated
QP = QPt + QPn
Q = Qm + Qp
F = P + K
LSC = LS + LC
Lst = Qp + Lsc
L = LV + Lm + LSC
QFL%Q = lOOQ/ (Q
+ F + L)
QFL%F = 100F/(Q + F + L)
QFL%L = lOOL/(Q + F + L)
LmLvLsc%/Lm = lOOLm/L
LmLVLSC%/LV = lOOLV/L
LmLVLSC%/LS = lOOLS/L
LvLstLm%Lm = l O O L m / L m + Lv + Lst
LVLStLm%LV = lOOLV/Lm + LV + LSt
LvLstLm%Lst = 100Lst/Lm + Lv + Lst
23
Darameters
Table 6. Means (x) and standard deviations (s) of point counts
on water well and outcrop samples. N = number of samples.
Uater Yells
Afton (25.1.6.333)
MT-1; N = 7
58
Ml-021
2.1x .35 43.8
s
4.2
3.8
Lanark (27.1.4.121)
MT-2; N = 5
11
M2-015
La Union (27.2.13.331)
MT-3; N
7
x
s.3
Norla (28.1.34.414)
MT-4; N = 5
10.3
(JL-49-04-469)
16.3
CUF I20.4
D
2.4
(JL-49-04-481)
N = 5
ID-009
3.0
.9
0
0.3x
s
1
.46
.I
x
s
Ls
28.0
3.2
7.0
2.1
17.6
2.8
.03
.34
.09
.5
.27
.25 0
26.3
4.4
9.1
.8
0
13.6
2.9
29.1
3.7
8.5
1.3
14.6
4.7
2.4 12.2 21.9
.9
.a
14.1
2.9
0.8
1.8
2.6
.?a
6.0
3.0
0
4.0
0
0
0
QPt
ppn
P
K
19.4 11.6 21.7
3.2
43.8
3.54.2
0
0
32.8
.75 14.6 34.0
.3
.2
4.9
24
30
LV
0
.05
.I
.45
.3
.2
.I
.05
.1
.7
.5
.8
.4
.6
.13
550
.28
1.0
Lm
15
.I
.2
.4
0
0
.28
.5
0
2.3
2.2
0
.4
.6
.2
0
.o
.42
.25
.30
.I
.14
4.4
100
LC
.25
18.1
8.3
3.5
1.4
17
2.2
Lm
26.2
3.2
5.8
0.4
Middle
Santa Fe Gp
N=2
LV
2.5
1.1
49.1
2.9
Qn
.2X
s.3
K
0
0
.15x
47.8
1.9 s.12
2.2
Mcrops
Upper
Santa Fe Gp 2.3
N = 7 1.8
1.9
P
.8
x .45 43.8
6
CWF 40
47.0
2.6
.5
26 0
3.3
0
Qpn
.37
x .4542.4
s.45
.45
QPt
Qn
LC
.I
.I
.8
.4
.2
0
0
Sand Petrography of Selected Samples of Well Cuttings
Well cuttings analyzed petrographically consist of loosely consolidated,
moderately to well sorted sands that can be classified as lithic arenites and litharenites
after Folk (1974). Sand grains are fine- to coarse-grained and subangular to
subrounded. As shown on Table 6, monocrystalline quartz (42-49%) and plagioclase
(20-29%) are the dominant detrital grains in the well cuttings. Many quartz grains are
clear, exhibit rapid extinction and overgrowth rings. Detrital plagioclase and plagioclase
phenocrysts occurring in rock fragments range in composition from oligoclase to
labradorite, but most are andesine (determined by the Michel-Levy method), T h e
grains usually display twinning and sometimes oscillatory zoning. Most feldspar grains
are fresh, but some show sericitic alteration. Volcanic-rock fragments (10-16%) ?.re the
dominant lithic fragment. They-exhibit .porphyritic:and::microlitic textures and appear to
be mainly andesitic. Most potassium feldspars are orthoclase and sanidine, but
significant amounts of microcline are also present. Minor amounts of detrital che.rt (23%), carbonate-rock fragments (<1%), sedimentary-rock fragments (<1%), and
metamorphic-rock fragments (< < 1%) occur.
When the point counting results are plotted.on the various ternary diagrams
(Figs. 5 and 6), little variation in sand composition-isseen with depth except for a slight
increase in lithic fragments (L) and a decrease in potassium feldspar (K). Most cf the
point counts cluster in the same general field. The only exceptions are samples hrl-021
(Afton), M2-015 (Lanark), and CWF 1D-009 on Fig. 5 and Table 6. These samp'es
contain very high percentages of lithic fragments and represent pre-Santa Fe or b w l
Santa Fe Group deposits.
On the QFL plots, wells CWF 1D and CWF 4D have the highest mean quartz
percentages (51.8 and 50.4) whereas wells MT 1and 2 (Afton and Lanark) have the
lowest (46.3 and 45.8). Feldspars averaged between 3437% in all wells, with K-feldspar
being relatively abundant only in the Canutillo Well Field (CWF, Table 6, Appendix A),
particularly in well CWF 1D located east of the Rio Grande at the base of the Franklin
Mountain block. Lithic fragment percentages are highest in wells MT 1 and 2 (19 and
18.7) and lowest in wells MT 4 (Noria) and CWF 4D (11.3 and 14.7). Except for the
bottom
sample from CWF-lD, the LvLsLm plots show no groupings, as more than 90% of all
lithic fragments are volcanic in origin with 3-5% being sedimentary and < l %
metamorphic. Similarly, the LvLstLm plots also show a concentration of points in one
general field as samples from all wells contained about 2-3% chert.
Comparison with Santa Fe Group Outcrops
Results of point counts on the outcrop samples are also summarized on Ta4le 6,
listed in Appendix A, and plotted on Fig. 7. Except for the two Rodey samples, all
outcrop samples plot within the same fields on the ternary diagrams as the well cutting
samples. All outcrop samples in the Mesilla and Palomas (T or C area) Basins are. from
the upper Santa Fe Group whereas the two Rodey samples are from the middle Smta
Fe - Rincon Valley Formation. The Rodey samples also had source areas that differed
from those of the middle Santa Fe units penetrated by test wells in the Mesilla Basin.
25
Figure 5. Ternary diagrams of sand-fraction petrography (thinsection point-count data, Tables 5 and 9 for well cuttings
from representative Sank Fe hydrostratigraphic unib at:
Afton (MT l),Lanark (MT 2), and Canutillo Well Field
(CFW 1D).
26
Fig. 5
0
AFTON
CWF- 1 D
i
F
Lm
Lv
Ls
Lm
-26,a
Figure 6. Ternary diagrams of sand-fraction petrography (thin-section point-count data,
Tables 5 and 6) for well cuttings from representative Sank Fe hydrostmtigrap’lic units
at: La Union (MT 3), Noria (MT 4), and Canutillo Well field (CWF 4D).
27
0
A
LA UNION
NORIA
CWF- 4D
Fig.6
P
fL2-"
F
L
Lv
Ls
Lm
Lv
Lst
27%
Figure 7. Ternary diagrams of sand-fraction petrography (thin-section pointaunt data,
Tables 5 and 6) for samples from representative Santa Fe Group outcrops.
28
Fig. 7
UPPER SANTA FE GROW
+TorC
x BOX CANlllN
Q
*
m
R
A
A
0
US H W Y 7 0
LAUNION
MIDDLE SANIAFE GROUP
o RODEY
F
L
Lm
Lv
Lst
28a
Overall, point counts (Figs. 5-7) from this study are consistent with counts by Mack
(1984) of samples from Santa Fe Group sandstone outcrops near Las Cruces.
Provenance
Sand samples analyzed from the six water wells and from the outcrop areac
(except the two Rodey samples) were derived from more than one source terrain. The
abundance of plagioclase (zoned and twinned) and andesitic lithic fragments str02gly
suggest an intermediate volcanic source area for most of the detrital grains. Che-t,
chalcedony, and abundant quartz (many well rounded with overgrowth rims) indirate
reworked sedimentary units as another major source. A granitic source area is also
suggested by the presence of microcline, strained quartz, and granitic rock fragments.
The paucity of metamorphic-rock fragments and tectonic polycrystallinequartz rules out
a metamorphic terrane as a major source area. In the middle Santa Fe Group Rodey
samples, the abundance of plagioclase and intermediate volcanic lithic fragments and
the paucity of quartz, chert and sedimentary lithic fragments strongly suggestan
intermediate volcanic terrane as the only major source area.
Due to lack of paleoflow indicators, it is difficult to determine the exact sw~rce
area for these deposits. However, it appears that even in early to middle Santa Fe time
(Miocene) the central MesiUa Basin area was receiving sediment from a very larg?
watershed aIea. A much larger source region was also available for sand and finer
grain-size material when the mechanism of eolian transport is taken into account. By
middle Pliocene time the ancestral Rio Grande was delivering even pebble-size material
to the basin from source terranes as far away as northern New Mexico (e.g. pumirx and
obsidian from the Jemez and Mount Taylor? areas). In most cases, visual and birocular
microscopic examination of the gravel-size (>2mm) fraction is still the best way to
establish local versus regional provenance of coarse-grained fluvial and alluvial deposits.
29
IV: A CONCEPTUAL HYDROGEOLOGIC MODEL OF THE MESILLA FASIN
Introduction
The conceptual model of the Mesilla Basin's hydrogeologic framework and its
development are descnied in this section. Emphasis is on stratigraphic and lithologic
characteristics of basin and valley fills, intrabasin geologic structures, and basinbounding bedrock features that influence the movement, storage, recharge, discharge,
and quality of ground water. The area covered extends from the Mesilla Valley on the
east, the Robledo and East Potrillo uplifts on the west, 1-10 (west of Las Cruces) on the
north, and the International Boundary (west of El Paso) on the south (Plate 1). The
base of the model is at 1000 ft (305 m) above mean sea level (Plates 16 and 17); and
the water table elevation in the area ranges from about 3750 to 4000 ft (1145-1220 m).
Highest basin elevations are about 4400 ft (1340 m), .and,vadosezone thickness e-wxeds
400 ft (120 m) in a few areas outside the Mesilla Valley. Much of the zone of
saturation occurs in basin fill that ranges from unconsolidated sand, silt, clay and gravel
to partly indurated deposits with layers of sandstone, mudstone and conglomerate. The
major aquifers in the area are in the upper 1500 ft (455 m) .of the saturated section.
The conceptual model is presented in a combined map and cross-section format
(Plates 1, 16, 17), with supporting lithologic, stratigraphic, petrographic, geophysical and
geochemical data illustrated in Plates 2-15, and listed in Tables 1 to 4. Informatilm on
thin-section petrography of the sand-size fraction was discussed in the preceding section
(m>,with supplemental data in Appendix A. A three-dimensional view of basin
hydrogeology is provided by eight cross sections, comprising five cross-basin profiIes
(approx. west to east; Plate 16) and three longitudinal sections that have a general south
to southeast orientation (Plate 17). Horizontal scale is 1:100,000 (approx. 0.6 in Fer mi)
and vertical exaggeration is 1OX (approx. 1.2 in per 1000 ft, 1 cm = 100 m). Supporting
geological, geophysical (resistivity-log) and geochemical data on individual wells are
graphically illustrated in columnar diagrams with a vertical scale of 1in = 100 ft (1 cm
= 12.2 m) and unspecified horizontal scale (Plates 2 to 11). The spatial arrangerent of
wells on these diagrams corresponds to the cross-section format of Plates 16 and 17.
The basic geologic elements that form the,model's framework were descriied in
Section II; and historical development of hydrogeologic concepts was outlined in the
discussion of previous work (Section I). Earlier .descriptions of basin hydrogeologr
(Conover, 1954; Leggat et al., 1962; King et al., 1969; Wilson et al., 1981; Hawley. 1984)
were based on limited subsurface data. With the exception on a few deep oil-test holes
(e.g. 25.1.32.141, and 26.1.35.333) and a water well at the M A R C 0 site (25.1.16.111),
deep exploration of the Santa Fe Group was confined to areas in or close to the Pfesilla
Valley. Inferences on basin-€dl thickness and aquifer characteristics were, for the most
part, based on interpretations of uncalibrated surface geophysical data (Merman, 1982;
Birch, 1980; Figuers, 1987; Gates et al. 1980; Wen, 1983; Wilson et al., 1981; Zoh'ly,
1969; Zohdy et al., 1976).
The present investigation is the first attempt to systematically analyze borehole
geophysical and petrographic characteristics of the Santa Fe Group over a large p , ~ roft
the Mesilla Basin. The conceptual model discussed in this section also contains r a n y of
the hydrogeologic features observed in other Rio Grande rift basins (e.g. Gustavson,
1991; Hawley and Haase, 1992; Hearne and Dewey, 1988; Lozinsky, 1987, 1988), and it
30
is important to note that, throughout the region, current estimates of thickness a.1d
areal extent of major aquifer units within the Santa Fe Group are significantly le-s than
earlier interpretations. For example, compare Haase and Hawley (1992) with Bjorkland
and Maxwell (1961) in the Albuquerque Basin, and King and others (1971), Wilsqn and
others (1981), and Hawley (1984; Appendix B) with Plates 2 to 10, 16 and 17 in this
report. Still further improvements in characterization of basin hydrogeology w
l
l
ionly be
possible when additional borehole geophysical data are available in a digital fonrat,
where there is more depth-specific geochemical information, and when representative
core samples have been obtained from the major aquifer units and confining bed:. The
electrical resistivity logs (standard, single-point, and dual induction), drill-cutting sample
suites, seismic-reflection profiles, and drill-stem geochemical data used in the present
study clearly need to be supplemented with more-sophisticated subsurface and su-face
information.
Hydrostratigraphic Subdivisions of Basin and Valley Fills
The basic hydrogeologic .unit used in conceptual-model-,developmentis the.
hydrostratigraphic unit. This informal geologic-material subdivision is analogous to a
rock-stratigraphic unit of formational rank: the basic ,mappable body of rocks
(sedimentary, igneous, and metamorphic) or unconsolidated earth materials. The.
hydrostratigraphic-unit concept used here (as well as in other parts of North America;
Back et al., 1988; Barrash and Morin, 1987) requires that it be definable in terms of
environment of deposition (of sedimentary strata) or emplacement (of igneous bodies),
distinctive lithologic features (textures, mineralogy, sedimentary structures), and general
time of deposition or emplacement (in a dated sequence of strata or igneous everts).
Geohydrologic characteristics must be definable, and a hydrostratigraphic unit must be
mappable in subsurface, as well as at the surface, at a useful map scale in terms of
ground-water resource management (e.g. 1:24,000 to 1:250,000).
The attributes of four major hydrostratigraphic units (RA, USF, MSF, LSF) and
one minor (VA) unit, into which basin deposits have been subdivided, are descnied in
Table 1. The major subdivisions of Santa Fe Group basin fill. (Upper, Middle and
Lower units - USF, MSF, LSF) broadly correspond to the informal rock-stratigraphic
subdivisions discussed in Section II. The river alluvium (RA) unit forms the upper part
of shallow aquifer system in the Mesilla VaUey: The eight diagrammatic cross sections
of the Mesilla Basin (Plates 16 and 17) illustrate representative distribution patterns of
hydrostratigraphic units in subsurface.
Because of the large (lox) vertical exaggeration and diagrammatic nature of the
cross sections (Plates 16 and 17), the inclination (dip) of faults and stratified sequences
cannot be accurately shown. Fill units, however, are highly deformed only in narrqw
zones adjacent to major faults. True dips of even basal Santa Fe units rarely exceed 1020", and the Upper Santa Fe Unit (USF) is nearly level (Fig. 4; Appendix B - Havley,
1984).
Lithofacies Subdivisions of Basin and Valley Fills
The second major feature of the hydrogeologk model is the subdivision of basin
deposits into distinct material categories (lithofacies) that are defined primarily on the
31
basis of sediment texture, degree of induration, geometry of bodies of a given textural
class, and distribution pattern of zones of contrasting texture. They form the basic
building blocks of the conceptual model developed for this study. The ten-unit
lithofacies clasiflcation system used here (Table 3) is a modification of a scheme
originally developed by Hawley (1984; Appendix B) to facilitate numerical model'ng of
groundwater systems in the Mesilla Bolson area between Las Cruces and El Pasc by the
New Mexico Water Resources Research Institute (Peterson et al., 1984). The
lithofacies categories and their subdivisions are defined in Table 3; and a distribution
pattern of these units in Mesilla Basin HI is illustrated on Plates 16 and 17.
These fundamental hydrogeologic components of basin and valley fills have also
been recognized in all major basins of the Rio Grande rift in New Mexico and adjacent
parts of Colorado, Texas and Chihuahua. (Spiegel and Baldwin, 1963; Hawley et al.,
1969; King et al., 1971; Hawley, 1978; Seager and Morgan, 1979; Gile et al., 1981;
Wilson et al., 1981; Seager et al., 1982, 1987; Chapin, 1988; Hearne and Dewey, 1978;
Brister, 1990; Gustavson, 1991; Lozinsky and Tedford, 1991). They have been formally
defined, however, only in the Albuquerque and Mesilla Basins (Hawley and Haase,
1992; this report). Anderson's.(1989) paper on "hydrogeologic facies models" relating to
"glacial and glacial fluvial sediments" is a n excellent account of how lithofacies-unit
concepts are being used in ground-water research in other geographical areas.
Lithofacies units I,JI,Ul,V and VI are unconsolidated or have only discontinuous
zones of induration. With the exception of subdivision 111, clean sand to pebbly sand
bodies are major components of these units and have relatively high hydraulic
conductivity. Clay, silty sand, and weakly indurated sandstone beds interstratified with
fine to coarse sand layers characterize lithofacies HI and IV. The latter facies is mainly
composed of thick, well-sorted sands that are partly cemented with calcite. Lithofacies
W to X are partly to well-indurated units with significant amounts of fine-graine,-l
material (silt-clay beds or a sand to gravel framework with clay-silt-fine sand matrix).
Channel deposits of the modern and ancestral Rio Grande (facies I and JI\,
which are the major components of hydrostratigraphic units RA and USF, form the
most important aquifer and potential enhanced-recharge zones in the basin. Coarsegrained distributary channel deposits of large alluvial fans in the Middle and Upp-r
Santa Fe units (MSF and USF; parts of facies V and VI) may also have good aquYer
potential in local areas. Thick, buried dune-sand deposits in the Lower Santa Fe unit
&SF, facies IV) are demonstrably a major "deep" aquifer in the CanutiUo Well Field
area. Units with very limited potential for ground-water production are partly- to wellindurated piedmont deposits (facies VI1 and V I q , and thick sequences of fine-grained
and locally saline basin-floor sediments that include extensive playa-lake beds in the
X and X).
southern part of the basin (facies J
Inferred subsurface distribution patterns of lithofacies within the five
hydrostratigraphic units at specific sites in the Mesilla Basin are shown on Plates 16 and
17. Documentation of these patterns varies from good (where petrographic analysis of
drill cutting, bore-hole geophysical logs, and detailed drilling records are available) to
strictly inferential (where few or no field data exist). T h i s variation in basic data quality
is clearly illustrated in the lithofacies interpretations given on Plates 2-11, 16 and 17. In
the large areas and/or depth zones without adequate subsurface control only the most
32
general features of the major hydrostratigraphic units can be shown, and the resrltant
conceptual model is based only on inference (i.e. best guesses). However, one important
generalization can be made: AU basin-fill units become finer grained to the south; and
fine- to medium-grained basin-floor facies are dominant in the international-boundary
zone west of Cerro de Cristo Rey (Plate 16e; facies 111, IX and X. How far this fining
trend in basin-fill deposits continues into the Bolson del Muertos area of northern
Chihuahua is not known. Major aquifers in the border region south of Santa Ter-sa
(Plates 6 and 9) will probably be confined to the upper Middle Santa Fe unit (facies II
and III, Plate 16e) since the Upper Santa Fe is almost entirely in the vadose zone.
The next step in characterization of lithofacies components of hydrostratigaphic
units, and one that is beyond the scope of this report, will be to formally assign ranges
of hydraulic conductivity values to individual lithofacies or groups of facies in
cooperation with other members of the USGS-WRD, NMSEO and NMBMMR staffs.
In the present conceptual model, extensive, thick-bedded deposits of fluvial sand and
gravel deposits (lithofacies I and 17) are.considered to have relatively high hydraulic
conductivities (e.g. in the 30 ft to 300 ft/day, 10-100 m/day range), while playa-lake clays,
silts and mudstones (lithofacies IX and X)or well-cemented sandstones and . fanglomerates (facies VII and VIIIj' have very low conductivities (commonly much less
than 0.3 &/day, 10 cm/day). Lithofacies H
I to VI should be expected to have average
conductivities in the moderate to low range (about 30 to 0.3 ft/day, 10-0.1 m/day), See
Frenzel and Kaehler, 1990; and Kernodle, 1992 for detailed information on expec.ted
ranges in hydraulic conductivity values and other parameters in ground-water-flow
systems.
In many valley-border areas, coarse-grained river channel deposits of the IJpper
Santa Fe and younger valley-fiU units (USF, VA and RA) are in duect contact (Gie et
al., 1981). This relationship has a very negative context in terms of waste managment
problems (Stone, 1984); but it also offers exciting possibilities for much more efficient
conjunctive use of surface- and ground-water resources (e.g. artificial recharge) at a
number of sites.
Structural and Bedrock Elements of Hydrogeologic Framework
The third major component of the-basin's.hydrogeologicframework includes the
bedrock units and structural features that form important boundary zones with respect
to saturated- and vadose-zone processes (Table 2). Igneous-intrusive bodies and
associated extrusive (volcanic) units within the basin-fill sequence are also locally
signiticant parts of the hydrogeologic framework. Structural interpretations are based
on geologic studies reviewed in Section 11, and geophysical and geothermal-resour-e
investigations, some of which are unpublished (Akemann, 1982; Cunniff. 1986; D:
Angelo and Keller, 1988; Figuers, 1987; Gross and Iceman, 1983; Reynolds & Assoc.,
1986, 1987; Snyder, 1986; Wen, 1983; Zohdy, 1969; Zohdy et al., 1976). Areal
distribution of major structural elements is shown on Plate 1. Surficial geology fo- most
of the area (at a 1:125,000 scale) has already been, or will soon be published (Sea7er et
al., 1987; in press). Igneous and sedimentary bedrock units form the basin floor and
margins, and vertical to near vertical lines on the cross sections (Plates 2-11, 16, 17)
show major boundary and intrabasin faults and a volcanic feeder conduit (plug or dike).
33
One of the most significant results of the present study is that there is now much
better definition of the basin-fillbedrock contact. Compare Plates 16 and 17 with
interpretations by Wilson and others (1981) and Hawley (1984; Appendix B). However,
additional drilling and geophysical studies, including seismic reflection surveys, will lead
to significant refinements in identification of basin-boundary conditions, particularly in
the northeastern and south-central basin areas.
Bedrock units (Precambrian to middle Tertiary, Section II) are generally
considered to be low-permeability boundary zones in ground-water-flow models (Frenzel
and Kaehler, 1990; Kernodle, 1992). However, upper Paleozoic (PennsylvanianPermian) and Cretaceous carbonate rocks such as are present in the East PotriUc,
Robledo, Franklin and Juarez uplifts may locally provide conduits for significant
amounts of ground-water movement A temperature.-login carbonate rocks at the south
end of the East Potrillo uplift (Snyder, 1986; Plate 7, Table 4a, 29.1W.6.410) which has
isothermic profile segment indicates significant ground-waterflow (at least in that. local
area).
Basin-Boundary Faults and Santa Fe Group Thickness
The structural segmentation of the basin into three major sub-basins ( N W , SW,
and E) and the mid-basin uplift is discussed in Section IT. Basin fill thickness exceeding
2000 ft (610 m) is well documented by borehole data only in the Eastern (LaUnimMesquite) and southernmost Southwestern subbasins (Plates 1, 3-7, 16 b-e, 17, Table
4a). Significant thinning of basin fill over the Mid-basin uplift (to about 1500 ft, 455 m)
is also well documented (Plates 3, 4, 7-9, 16 bc, 17 b-c). Estimates of basin-fill
thickness in most parts of the Northwestern and Southwestern subbasins are based in
the premise that deposits in those areas, even near the East Potrillo and Robledo faults,
will not be thicker than fills in parts of the Eastern subbasin that are adjacent to the
relatively large mountain masses of southern Organ and Franklin uplifts.
Structural Influences on Intrabasin Sedimentation Patterns
Because the Mesilla Basin is part of an active tectonic.zone (Rio Grande rift)
that has been evolving for more than 25 million years (Section II), the distribution
pattern of hydro-stratigraphic units and.lithofacies in space and time (Plates 1.6 and 17)
must be interpreted in terms of ongoing crustal extension and basin subsidence. Active
local extension of the earth's crust and differential,movement, including rotation, of
basin and range blocks are the basic structural controls on basin sedimentation. As is
evident from the impact on Quaternary geomorphic processes by climate change d a t e d
to Quaternary glacial-interglacial cycles, forces other than rift tectonism can also
materially innuence erosion, sediment transport, and deposition (Frostick and Reid,
1989). However, on the geologic-time and space scale represented by Santa Fe Gmup
deposition, structural deformation and associated igneous activity are the dominant
factors that will be considered here in terms of controls on basin sedimentation.
The Lower Santa Fe hydrostratigraphic unit (early to middle Miocene) and
associated lithofacies (primarily I V , W, VIII, IX,and X ) were deposited in a brold,
shallow basin that predated major uplift of the flanking mountain blocks (uplifts)
bounded by the Mesilla Valley, East Potrillo and East Robledo fault zones (Plates 1, 16,
34
17). The deepest and most actively subsiding part of this basin appears to have been in
the "Southwestern" area east of the East Potrillo uplift (Plates 7 and 16e).
Petrologic studies of drill cutting and core discussed in Section 111, as well as
interpretations based on detailed analyses of samples and drillers logs (Plates 2-11,
Tables 4a and 4b), indicate that depositional environments in the Lower Santa Fo
hydrostratigraphic unit V U ) contrast markedly with those in younger basin fill.
During early stages of basin filling, the Mesiua Basin received a major innw of Fne- to
medium-grained sediments (muds to sands) from adjacent upland source areas that were
sites of late Eocene and Oligocene volcanic activity. Since high mountain areas (such as
the present Organ-Franklin-Juarez chain) had not yet formed, wedges of coarse-rrained
piedmont deposits were limited to the extreme basin margins. The most striking
features of the Lower Santa Fe ;unit (LSF) .are thethick deposits of clean, fine to coarse
sand (lithofacies IV), noted in the Eastern (La Union-Mesquite) and Southwestern
subbasins, that have been interpreted as buried dune fields in the Canutjllo well-field
area and elsewhere in the basin (Cliett, 1969; Wilson et al., 1981; Hawley, 1984). These
partly-indurated beds are as much as 600 ft, (185 m) thick in the eastern (La UnimMesquite subbasin); and they may be 900-1000 ft (275-305 m) thick in the southwestern
subbasin immediately east of the east Potrillo fault zone (Plates 3-5, 7, 10, 11, 16b-e,
17a).
Distribution patterns of both piedmont-slope and basin-floor lithofacies (I,lI,III,V
to IX) in Middle and Upper Santa Fe hydrostratigraphic units (MSF and USF) have
also been greatly influenced by differential subsidence of basin fault blocks behve?n the
Mesilla Valley fault zone on the east, and the East Robledo and mid-basin faults on the
west (Plates 1, 16, 17). As has been previously noted (Section 1I) tectonic subsidence
has been most active in areas adjacent to these fault zones particularly in the Eastern
(l.a Union-Mesquite) subbasin.
The Middle Santa Fe unit was deposited during late Miocene to early Pliocene
time when maximum differential movement occurred between the central basin blocks
and the Doka Ana-Tortugas, southern Organ, Franklin, Juarez, East Potrillo, Robledo
and Mid-basin uplifts. East of the Rio Grande Valley, both the Middle and Upper
Santa Fe units (MSF and USF) are dominated by coarse clastic material (fan alluvium)
derived from the rapidly rising southern Organ and Franklin uplifts (Lithofacies \'to
Vm>. The developing Robledo and East Potrillo Mountains contributed fan.sedi-nents
to the western subbasins during the same interval. Lithofacies III is the major
component of the Middle Santa Fe unit in the broad central-basin area that extends
west from the Mesilla Valley. It is as much as 1000 ft (305 m) thick in the eastern (La
Union-Mesquite) subbasin (Plates 3-5, 10, 11, 16b-d, 17a). This sequence of
interbedded sand and silt-clay beds also forms the basin's thickest and most extensive
aquifer system ("medial aquifer" in this report, Tables 4a and b).
East of the Mesilla Valley fault zone, fan deposits (facies V and Vn) progrsded
westward almost to present location of 1-25 during much of the Middle Santa Fe
interval. Similar but smaller alluvial aprons extended basinward from the Robledo and
East Potrillo uplifts. Complex intertonguing of piedmont-slope and basin-floor
sediments is observed in the Middle Santa Fe unit beneath the Mesilla Valley (Plate
17a; MSF; lithofacies II,III,V,VIl, and IX). Analyses of drillers and sample logs shows
35
a mixture of alluvial-fan and basin-floor facies derived from local sources. A precursor
to the through-going (ancestral) Rio Grande system may have contributed a large
volume of fluvial sand and mud to actively subsiding areas, at least in the northern part
of the basin, during latest stages of Middle Santa Fe deposition. Basin-floor
aggradation ultimately outpaced basin subsidence and a nearly-level alluvial plair with
scattered playa-lake depressions extended across most of the basin area.
The Upper Santa Fe unit was deposited during a 2-3 million year interval when
large volumes of sediment were washed into the basin by distributaries of the ancestral
Rio Grande system that headed as far north as the San Juan and Sangre de Cristo
Mountains of southern Colorado (Southern Rocky Mountain province). This fluvial
system discharged at various times into playa-lake plains on the Tularosa Basin a1d
Hueco Bolson (via Fillmore Pass;Fig. l), as well asthe Bolson de Los Muertos
(Hawley, 1975, 1981; Hawley et al., 1976; Gile et al., 1981; Seager, 1981; Gustavslm,
1991).
The final phase of widespread basin aggradation throughout the central ard
I
)
occurred during eruptions of the
southern New Mexico region (lithofacies Ib and I
Jemez volcanic center that produced the Bandelier Tuff and the Valles caldera 1 to 1.6
million years ago (Smith et al., 1970; Gardner et al., 1986;.Goff et al., 1989). At that
time braided channels of the ancestral Rio Grande shifted across a broad fluvial plain
that included most of the present Mesilla Valley and West Mesa (La Mesa) area (Fig. 1,
Plate 1). Complex intertonguing of ancestral Rio Grande and piedmont slope-facies
(I,II,III and V) characterize the upper Santa Fe Unit (USF)) east of the Mesilla Valley
fault zone (Plates 16 and 17). At times progradation of alluvial fans from the Organ
and Franklin uplifts was very active (lithofacies V), and the piedmont alluvial aprm
expanded across the Mesilla Valley fault zone as far west as the present central Mesilla
Valley.
The patterns of Upper Santa Fe sedimentation are clearly influenced by bcth
local and regional volcanic and tectonic processes, as well as by early Pleistocene and
Pliocene climate cycles. Structural deformation has produced more than 2000 ft (610
m) of subsidence in the Eastern subbasin since middle Miocene time (past 10 mXion
years). Hundreds of feet of basin subsidence have also occurred along the Mesilla
Valley, East Potrillo and East Robledo faults in Pliocene,and Quaternary time. (past 4-5
million years) and clearly influenced the final position of the ancestral Rio Grand? and
the distriiution patterns of lithofacies (I,II+IIl and V) in the Upper Santa Fe
hydrostratigraphic unit (USF; Plates 16, 17). Differential movement along the major
basin-bounding fault zones shown on Plate 1continued in post-Santa Fe (Quaternary)
time and has controlled the position of the inner Mesilla Valley and bordering river
terraces from the Selden Canyon to Paso del Norte narrows (Fig. 1). Valley fills units
(VA) are definitely offset by faults east of the Robledo Mountains (Gile et al., 19;?1).
36
v. SUMMARY
Introduction
This report descriies the results of a hydrogeologic study by the New Mexico
Bureau of Mines and Mineral Resources (NMBMMR) in the Mesilla Basin between Las
Cruces, New Mexico and the International BoundaIy west of El Paso, Texas. T h s two
major study objectives were (1)to develop a detailed conceptual model of the bacin's
hydrogeologic framework that is based on a synthesis of all available geological,
geophysical, and geochemical data, and (2) to present that information in a format
suitable for use by the U.S. Geological Survey, Water Resources Division (USGS-WRD)
in developing numerical models of the ground-water flow system. These modelling
efforts will, in turn, provide a much more quantitative base for management decisions
on future strategies for water-resource development.,and conservation. Predictive
models are particularly important because of the potential for water quality degradation
and land subsidence due to excessive ground-water withdrawals that have been proposed
in some parts of the Mesilla Basin.
Funding for the initial phase of data compilation and model development in 1987
was jointly provided by the NMBh4MR and the U.S. Geological Survey, Water
Resources Division (USGS-WRD, contract no. 14-08-D001-G-726), and subsequent
support has been furnished by the NMBMMR. Work was done in cooperation with
personnel of the USGS-WRD Albuquerque, Las Cruces, and El Paso offices, Nev
Mexico State Engineer Office,and El Paso Water Utilities Department.
In its simplest form, the conceptual model of a basin's hydrogeologic framework
is a graphic portrayal of (1)the lithologic character; geometry, and geologic history of
basin-fill deposits; and (2) the bedrock units and structural features that form the basin
boundaries and influence intrabasinal depositional environments. When firmly based on
adequate (geological and geophysical) data on subsurface conditions, the model
characterizes the basic "architecture" of mappable subdivisions of basin deposits that can
be defined in terms of their aquifer properties.
The fill of the Mesilla Basin has two basic hydrologic components: Santa Fe
Group basin fill and Rio Grande Valley fill. In terms of volume and areal extent, the
Santa Fe Group forms the bulk of basin-fibg deposits. It comprises a very thick
sequence of alluvial, eolian, and lacustrine sediments dep0sited.h intermontane basins
of the Rio Grande rift structural province during an interval of about 25 million years
starting in late Oligocene time. Widespread filling of several structural subbasins, which
in aggregate form the Mesilla Basin, ended about 700,000 years ago (early Middle.
Pleistocene time) with the onset of Rio Grande (Mesilla) Valley incision.
Post-Santa Fe Group valley fills include (1) inset deposits of the ancestral Rio
Grande and tributary-arroyo systems that form terraces bordering the modeni
floodplain, and (2) river and arroyo alluvium of the inner valley area that has bee?
deposited since the last major episode of Rio Grande Valley incision in late Pleistxene
time (about 15,000 to 25,000 years ago).
The three basic hydrogeologic components of the MesiUa Basin model comprise:
1. Structuralandbedrockfeatures. They include basin-boundary mountah
uplifts, bedrock units beneath the basin fill, fault zones within and at the
edges of basin that innuence sediment thickness and composition, and
37
igneous-intrusive and -extrusive rocks that penetrate or are interbedded with
basin deposits.
2. Hydrostratigraphic units. These mappable bodies of basin and valley fill are
grouped on the basis of origin and position in a stratigraphic sequence.
Genetic classes include ancestral-river, present river-valley, basin-floor playa,
and piedmont alluvial fan deposits. Time-stratigraphic classes include units
deposited during early, middle and late stages of rift-basin filling (i.e. lower,
middle and upper Santa Fe Group), and post-Santa Fe valley fills (e.g.
channel and floodplain deposits of the Rio Graude, and fan alluvium of
tributary arroyos).
3. Lithofacies subdivisions. These units are the basic building blocks of t’le
model. In this study, basin deposits are subdivided into ten lithofacies (I
through X) that are mappable bodies defined on the basis of grain-size
distribution, mineralogy, sedimentary structures, and degree of postdepositional alteration. They have distinctive geophysical, geochemical, and
hydrologic attributes.
Report Format
The report has four major narrative sections (I. Introduction; 11. Geologic
Setting; nI. Sand-Fraction Petrography; and IV. Conceptual Model), a comprehcnsive
reference list, and two appendices (A. Basic petrographic data, and B. Preliminary
hydrogeologic cross sections that extend into adjacent parts of the Jomada and H.leco
basins). The hydrogeologic framework of the Mesilla Basin area as defined by Frenzel
and Kaehler (1990) is graphically presented in map .and cross-section format (Plates 1,
16 and 17). Supporting stratigraphic, lithologic, petrographic, geophysical, and
geochemical data from 61 wells are illustrated in stratigraphic columns and
hydrogeologic sections (Plates 2 to 15). Tables 4a and 4b summarize the subsurface
information used in this study, including (1) well location and depth; (2) ground-vater
levels; (3) drill-stem sample intervals; (4) selected data on ground-water chemistry: and
(5) data sources. Major hydrostratigraphic units and aquifer zones sampled are a!so
identified in Tables 4a and 4b.
Section I
The introductory section of this report outlines previous work on basin
hydrogeology, particularly that done since 1962 when the senior author started his
investigations in the Las Cruces area of Doiia Ana County. Study methods and
techniques are also covered in this section. Emphasis is on the team approach u x d in
the analysis of borehole (geological, geophysical, and geochemical) data to develo-, the
final conceptual model of hydrostratigraphic and lithofacies unit distribution.
Section II
Section I1 provides a general geological overview of the Mesilla Basin regicn
including the structure of flanking mountain uplifts and relationship to contiguous basin
areas. The area discussed comprises parts of the Jornada del Muerto, Tularosa, Fueco,
and Los Muertos basins in New Mexico, Texas, and Chihuahua Emphasis is on t’le
38
relatively recent interval of geologic time (-past 25 million years) when major
structural and topographic elements of the present landscape formed (Seager an?
Morgan, 1979; Gile et al., 1981; Seager et al., 1984, 1987). The interval was
characterized by regional extension of the earth's C N S ~ and differential uplift,
subsidence and tilting of individual crustal blocks along major fault zones to fonr
internally complex basins and ranges. This continental "rifting" process produced the
Rio Grande rift structural zone that extends from southern Colorado to western Texas
and northern Chihuahua Rift basin fiUs that predate Pleistocene entrenchment of the
Rio Grande Valley system comprise the Santa Fe Group.
The Mesilla Basin is near the southern end of the rift zone and is relatively
shallow in comparison to many other rift basins (Chapin, 1988, Lozinsky, 1987, 1388;
Brister, 1990; Hawley and.Haase, 1992). :Maximum'thickness of upper Cenozoic fill is
about 3,000 ft (1900 m). The lower and middle parts of the Santa Fe Group form the
bulk of the basin fill. These units were deposited in an internally drained complcx of
three subbasins that were initially separated by a.central (north-trending) intrabasin
uplift (Eastern, Northwestern, Southwestern subbasins, and-Mid-basin uplift on P:ate 1).
Even though differential movement of intrabasin and -basin-bounding faults:continued
throughout late Cenozoic time, the basin-filling process outpaced structural
deformation; and individual fills of early-stage subbasins ultimately coalesced to form
the widespread blanket of basin fill that characterizes the upper part of the Santa Fe
Group.
Eolian sands and fine-grained playa-lake sediments are major lithofacies in the
lower and middle Santa Fe Group. These units are locally well indurated and only
produce large amounts of good-quality ground water from buried dune sands (lower
Santa Fe) in the eastern part of the basin beneath the Mesilla Valley. Poorly
consolidated sand and pebble gravel deposits in the middle to upper part of the Smta
Fe Group form the most extensive aquifers of the area. Widespread channel depxits of
the ancestral Rio Grande €irst appear in upper Santa Fe beds that have been datcd at
about 3.5 million years (Ma) in southern New Mexico and 2.5 Ma in western (TrrnsPecos) Texas.
Expansion of the Rio Grande (fluvial) system into upstream and downstream
basins, and integration with Gulf of Mexico drainage in the early t o middle part of the
Quaternary (Ice-Age) Period about 700,000 years ago led to rapid incision of the
Mesilla Valley and termination of widespread basin aggradation (ending Santa Fe
Group deposition in the Mesilla Basin). Cyclic stages of valley cutting and filling
correlate with expansion and contraction of Alpine glaciers and pluvial lakes in ths
southern Rocky Mountain, and Basin and Range region. These cycles are represented
by a stepped-sequence of valley border surfaces that flank the modem valley floor.
Fluvial sand and gravel deposited during the last cut-and-fill cycle form a thin, but
extensive shallow aquifer zone below the Rio Grande floodplain. Recent fluvial
sediments are locally in contact with ancestral river facies in the upper Santa Fe Cnoup,
particularly in the northern Mesilla Valley. They form the major recharge and
discharge zones for the basin's ground water, and are quite vulnerable to pollutior in
this urban-suburban and irrigation-agricultural environment.
39
Structural deformation of subbasin boundaries and topographic relief between
deeper basin areas and flanking uplifts continued to change over geologic time. For
example, during early stages of basin filling (lower Santa Fe deposition) many of the
present bounding mountain blocks had not formed or had relatively low relief. Thickest
basin-fill deposits (up to 1500 ft, 455 m, of middle Santa Fe Group) were emplamd
between 4 and 10 million years ago during most active uplift of the Organ-FranklinJuarez range and the Robledo Mountains, and subsidence of the Eastern (La UnionMesquite) subbasin. The major (Mesilla Valley) fault zone is now buried by the recent
valley fill beneath the present KOGrande floodplain.
Section IlI
The petrographic investigations ,descn%edin Section III emphasize the
fundamental properties of rock fragments and mineral grains,that in aggregate f o l n the
various lithofacies subdivisions of the five hydrostratigraphic units (Tables 1 and 2).
Tools needed to properly describe earth materials in fine .detail include the binoc-llar
microscope for preliminary drill-cutting descriptions;.the petrographic.(light) micrqscope
from rock and grain thin-section analyses, and.x-ray equipment and.the-scanning
electron Microscope for characterization of ultra-fine-scale features (e.g. grain-surface
features, cementing agents, and porosity). Only the binocular and petrographic
microscopes were used in this study to analyze the sand-size fraction from selected sets
of drill cuttings and outcrop samples. Anderholm (1985) describes preliminary x+ay
analyses of fine-grained materials from several Rio Grande Basins (including the
Albuquerque and Mesilla Basins).
Cuttings from the Afton (MTl),Lanark (MT2), La Union (MT3), and Noria
(MT4) were analyzed initially with a binocular microscope in order to construct a
stratigraphic column for each of these key wells (Plates 12-15) and to determine
intervals (approximately every 100 ft, 30 m) where subsamples of representative sands
would be collected for thin-section analyses. Samples were also collected from
representative sandy intervals in the two wells in the Canutillo Field (CWFlD and 4D)
and from six outcrops of the Upper and Middle Santa Fe units.
Sand samples analyzed from the.six water wells and from outcrop areas in the
Mesilla Basin were derived from more than one source terrane. lkabundance of
plagioclase (zoned and twinned) and andesitic lithic fragments strongly suggest an
intermediate volcanic source area for most of the detrital grains. Chert, chalcedony,
and abundant quartz (many well rounded with overgrowth rims) indicate reworked
sedimentary units as another major source. A granitic source area is also suggested by
the presence of microcline, strained quartz, and granitic rock fragments. The pau'5ty of
metamorphic-rock fragments and tectonic polycrystalline quartz rules out a metamorphic
terrane as a major source area. In the middle Santa Fe Group samples from the
Rincon Valley area (Rodey site), the abundance of plagioclase and intermediate
volcanic lithic fragments and the paucity of quartz, chert and sedimentary lithic
fragments strongly suggest an intermediate volcanic terrane as the only major source
area.
Due to lack of paleoflow indicators, it is difficult to determine the exact sorrce
area for these deposits. However, it appears that even in early to middle Santa Fe time
40
(Miocene) the central Mesilla Basin area was receiving sediment from a very larce
watershed area. A much larger source region was also available for sand and finsr
grain-size material when the mechanism of eolian transport is taken into account. By
middle Pliocene time the ancestral Rio Grande was delivering even pebble-size material
to the basin from source terranes as far away as northern New Mexico (e.g. pumice and
obsidian from the Jemez and Mount Taylor areas). In most cases, visual and binxular
microscopic examination of the gravel-size (>2mm) fraction is still the best way t7
establish local versus regional provenance of coarse-grained fluvial and alluvial deposits.
Section N
The conceptual hydrogeologic model is descriied in detail in Section lV and
illustrated on Plates 1, 16; and.17. These plates.are.published at a horizontal scale of
1:100,000 (1 cm = 1k m ; approx. 0.6 in/mi);and cross sections have vertical
exaggeration of1OX. The base elevation of the model is 1000 ft (305 m) above spa level
and the water table in central basin areas ranges from about 4000 ft (1220 m) to the
north and 3750 ft (1145 m) at the southeastem.end of the basin. Outside,the Messilla
Valley area the vadose (unsaturated) zone is commonly 300-to400 ft (90-120 m) thick.
Supporting geological, geophysical, and geochemical ,data above an elevation of 1500 ft
(455 m) are shown on stratigrapbic columns and hydrogeologic cross sections (Figs. 215) at a vertical scale of 1 in = 100 ft (1 cm = 12.2 m) and variable horizontal scale.
The basic hydrogeologic mapping unit used in conceptual model developm>nt is
the hydrostratigraphic unit. It is d e h e d in terms of (1) environment of deposition of
sedimentary strata, (2) distinctive combinations of lithologic features (lithofacies) such
as grain-size distribution, mineralogy and sedimentary structures, and (3) general time
interval of deposition. The attributes of four major (RA, USF, MSF, LSF) and o7e
minor (VA) classes into which the area's basin and valley fills have been subdividtd are
defined in Table 1. The Upper, Middle, and Lower hydrostratigraphic units of thSanta Fe Group roughly correspond to the (informal) upper, middle and lower ro2kstratigraphic subdivisions of Santa Fe Group described in Section II. The other major
hydrostratigraphic unit (RA) comprises Rio Grande alluvium of late Quaternary age
(< 15,000 yrs) that forms the upper part of the regional shallow-aquifer system.
The ten lithofacies subdivisions that.are.the fundamental building,blocks of the
model are defined primarily on the basis of sediment texture (gravel sand, silt, clay, or
mixtures thereof), degree of cementation, and geometry of bodies of a given textu-a1
class and their relative distribution patterns. Lithofacies I, 11, III, V, and VI are
unconsolidated or have zones of induration (strong cementation) that are not
continuous. Clean sand and gravel bodies are major constituents of facies I, 11, V, and
VI, while clay or cemented sand zones form a significant part of facies 111and IV.
Subdivision IV is characterized by thick eolian sand deposits of the lower Santa Fe unit
(LSF)that are partly cemented with calcite. Coarse-grained channel deposits of t'le
modem and ancestral Rio Grande (lithofacies I and II)are the major components of
the upper Santa Fe (USF) and river-alluvium (RA) hydrostratigraphic units. They form
the most important aquifers and potential enhanced-recharge zones in the basin.
Lithofacies VI and VIII are partly to well indurated piedmont-slope deposits; whil:
41
facies J
X and X comprise thick sequences of he-grained basin-floor sediments that
include playa-lake beds.
Assignment of specific hydraulic conductivity ranges to individual lithofacies
subdivisions is beyond the scope of this investigation. However, as a first
approximation, the following general ranges appear to be reasonable:
1. Conductivities of lithofacies I and 11 are relatively high (30 to 300 ft/da;r. 10100 m/day)
2. Lithofacies IX and X, and well-cemented sandstone and fanglomerate zones
in facies W and VI11 will definitely have very low conductivities (usually
much less than 0.3 ft/day, 0.1 m/day)
3. Conductivities in uncemented sand layers in lithofacies 111 and IV, and sand
and gravel beds in facies V through W I should primarily be in the
intermediate range (0.3 to 30 &/day, 0.1-10 m/day)
In addition to delineation of major hydrostratigraphic units and lithofacies
subdivisions in basin and valley fills, the other major contrihtion of this study ha. been
the significant improvement in definition of the physical limits of the Mesilla Bash and
its component subbasins. Most of this information on bedrock.and structural geology
was derived from geologic maps and cross sections, with supplemental data from
geophysical and geothermal surveys, that have been recently published or are in rress
(Figuers, 1987; Seager, 1989, in press; Seager and Mack, in press; Seager et al., 1987;
Snyder, 1986). Unpublished seismic reflection surveys done for the USGS-WRD in the
lower Mesilla Valley have also been very useful (C. B. Reynolds & Assoc., 1986, 1987).
Unconsolidated deposits make up the bulk of the middle and upper Santa Fe
Group and all of the recent valley fill in the Mesilla Basin. Textural classes inclule
sand, gravelly-sand, silt-clay, and sandy to gravelly materials with a silt-clay matrix
Secondary calcite and gypsum are the primary cementing agents in the basin fill;
however, continuously indurated zones are uncommon except in basal parts of the. Santa
Fe section. Very coarse-grained alluvium, with gravel primarily in the pebble- to
cobble-size range (<lo in, 25 cm), is confined to.narrow piedmont zones near the. basin
margins (lithofacies V-VIII). Layers of these.alluvia1-fan deposits are the basal Iccally
indurated (facies VI1 and VIII).
Widespread fluvial deposits of the ancestral Rio Grande form much of the upper
basin fill (unit USF, facies Ib and 11). In the northern half of the basin, fluvial mlterials
constitute the major shallow aquifer system in conjunction with the inner Mesilla Valley
fill (unit RA, facies IV). Outside the valley area, however, most of the ancestral river
deposits are in the vadose zone.
Interbedded sand and silt-clay deposits of the Middle Santa Fe Unit (MSU,.
primarily lithofacies nI) form the basin's thickest and most extensive aquifer systen (the
"medial" aquifer in this report; Tables 4a and b). This unit is as much as 1000 ft (305
m) thick in the eastern (La Union-Mesquite) subbasin (Plates 3-5, 10, 11, 16b-d, 17a).
Well-sorted fine to coarse sand deposits of lithofacies IV make up a significant pa-? of
the lower Santa Fe Unit (LSU) and are here interpreted as being primarily of eolian
origin. These partly-indurated beds are as much as 600 ft (185 m) thick in the eastern
42
(La Union-Mesquite subbasin); and they may be 900-1000 ft (275-305 m) thick in the
southwestern subbasin immediately east of the east Potrillo fault zone (Plates 3-5 7, 10,
11, 16b-e, 17a).
All basin fill units (USF, MSF, LSF) become finer grained to south, and fne- to
medium-grained basin-floor facies, with only minor amounts of gravel, dominate the basin
fill section in the international boundary zone west of Cerro de Cristo Rey (Plates 6,7, and
16e; facies 111, IX and X). Most of the Upper Santa Fe hydrostratigraphic unit (USF) in
that area is in the vadose zone; and sand beds in the basal Upper Santa Fe unit and upper
part of the Middle Santa Fe unit (MSF, lithofacies I
I
I
)appear to be the only major aquifer
east of the Mid-Basin uplift. Lithofacies IV in the Lower Santa Fe hydrostratigrzphic unit
(LSU) may also be a potential deep aquifer in the Southwestern subbasin, but this zone has
not yet been tested for either quantity or quality of ground water production.
Discussion
The conceptual model of the Mesilla areas's hydrogeologic framework developed for
this report (Plates 1, 16, 17) is simply what its name implies:
1. It is only a general representation of a very complex real-world system (Kemodle,
1992, p. 6-7).
2. The intellectual construct that is a "concept" can only be as good as the quality of
the scientific information used in its development.
3. The model's graphic portrayal is at least partly an artistic effort that rePects the
talents of its creators (or lack thereof).
We believe that the major features of this portrayal. of basin hydrogeology will stand the test
of time; however, there will always be room for improvements. The positive feedback loops
between assimilation of additional scientific information, better conceptualization, and
improved artistic skill will be enhanced as the model is tested and further developed.
43
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48
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49
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50
APPWDIX A
Basic Petrographic Data: Thin section analyses
of grain mounts of sieved sand
from representative borehole and outcrop samples of Santa Fe Group sands
sandstones, Dona Ana and Sierra Counties, New Mexico.
R. P. Lozinsky
-
2 mm size fractionof sandy intervalsin
Part I. Composition of the0.125
Santa Fe Group deposits penetrated by deep wells
test in the Mesilla Basin.
5 for explanation of
symbols.
Refer to Table
T e s t YeLL
S q l e # (Depth ft) Unit
F
P
LS
Lrn
L
Lrn
LV
LV
LSt
(PIK)
Aftm, H
T
l (25.1.6.3331
4
0
84
16
0
85
15
000
(
40’)
USF
47
30
(2515)
23
0
96
002
(
190’)
USF
47
32
(2715)
21
6 0
94
006
(
620’)
MSF39
44
17
1
90
79
9
1
0
93
7
0
72
28
20
(28/11)
010
(1050‘)
MSF
18 51
31
(2417)
013
(1370’)
MSF
51
35
(28/7)
14
0
93
7
0
80
20
016
(1670’)
LSF
43
39
(3316)
18
0
100
0
0
90
10
018
(1870’)
LSF
41
39
(3217)
20
0
96
4
0
84
16
021
(2180‘)
Tvs?
29
12
59
0
99
1
0
98
2
17
0
100
0
0
Ea
12
24
0
98
2
0
86
14
1
77
22
77
22
0
78
22
0
100
0
(2514)
Lanark ICR (27.1.4.121)
000
(
40’)
001
(
380’)
USF
44
USF33
43
39
(30/9)
(23110)
004
(
450’)
HSF
43
41
(3219)
16
2
90
8
008
(
880’)
MSF
47
30
(2218)
23
1
195
4
01 1
(1170’)
LSF34
51
15
30
97
100
0
100
(24110)
015
(1550’)
Tv
0
0
51
0
and
Test Well
S q L e # (Depth f t ) Unit
Q
F
tm
L
LV
Lm
LS
LV
LS?
(P/K)
La U
n
o
in Wn (27.2-13.331)
000
(
40')
USF
46
29
(2415)
25
0
93
7
0
83
17
003
(
380')
MSF
49
36
(29/7)
15
0
87
13
0
75
2r
008
(
830')
MSF
53
29
(24/5)
18
0
95
5
0
73
27
011
(1170')
HSF
51
38
(27111)
11
0
86
14
0
70
30
014
(1470')
MSF
50
41
(31/10)
9
0
83
17
0
59
41
018
(1840')
LSF
48
37
(2918)
15
0
90
10
0
85
15
020
(2020')
LSF
54
36
(22/14)
10
0
95
5
0
74
26
2
74
24
Yoria llT4 (28.1.34.414)
000
(
40')
USF
49
38
(28110)
13
6 2
92
001
( 160')
USF
44
32
(2319)
24
0
96
4
0
85
15
006
(
620')
MSF
47
38
(30/8)
15
0
98
2
0
78
22
009
(
970')
MSF
48
40
(32/8)
12
0
94
0
73
27
012
(1250') 13 MSF 39
4 0
96
0
77
23
47
(3217)
52
6
Test Well
Sample # (Depth f t ) Unit
Q
F
(P/K)
L
LSLm
LV
Lm
LV
LS?
M 1D (JL-49-04-4811
002
(
250')
14
MSF
37
49
0
93
7
0
84
16
0
80
20
0
59
41
0
74
2c
(21/16)
003
(
320')
"SF
004
(
440')
MSF
38
54
8
0
90
10
(19/19)
005
(
550')
LSF
008
(
800')
LSF
53
ow
(
900')
KP
10
35
(21114)
12
0
96
4
0
68
32
4
311 1
86
0
34
66
0
37
63
68
30
(
WF
4D CJL-49-04-4691
001
(
120')
MSF
002
(
230')
MSF
51
36
13
0
88
12
73
27
21
0
92
8
85
15
15
0
94
6
0
100
0
(24112)
003
(
350')
MSF
30
49
(19/11)
004
( 470')
LSF
49
35
13
87
(23113)
007
(
700')
12
LSF34
54
(21/13)
53
82
re
-
Part 11. Composition of the 0.125
2 mm size fraction of sandy intervals in
outcrops of the SantaPe Group. Refer to Table 5 for explanation of symbols.
a
Stratigraphic Unit
F
L
L S Lm
Lm
LV
LV
LSt
(P/K)
W p r Santa Fe Grorp
AN-la
43
3b
21
0
97
4
0
96
17 2
0
9a
1
97
0
3
0
a9
11
0
a3
17
0
7a
2
1
ea
11
9a
5
0
a1
19
(23/13)
AN-lb
21
45
34
m/a)
53
AN-3
22
(20/10)
tu-1
22
28
50
(la/lo)
70- 1
22 4a
2a
(17/13)
BC-3
45
37
(24/13)
la
0
96
4
0
86
14
TC-1
40
37
(25/12)
23
2
95
3
2
86
12
R-1
20
47
(31/16)
33
0
99
1
0
96
4
R-2
16
51
33
(3~13)
0
w
1
0
9a
2
lliddle Santa Fe G r r q
54
Part 1x1. Locations Of sampled Santa Fe Group outcrops,Dona Ana and Sierra
Counties, New Mexico
Upper S a n t a Fe (Camp
Rice
and
Palomas
Formations)
Anapra Includes 3 samples from upper Santa
located west of Sunland Park
(AN
295.43.18.1131
-
Fe Group outcrops
la, lb and 2);
La Union
Sample from upper SantaFe Group deposits exposed just west
of La Union (LU-1); 275.33.18.1411
US-70
Exposure along northside of US-70 just west of Las Cruces
ancestral river deposits(70-1); 23S.13.20.223
-
Box Canyon Sample from base of Ruhe’s (1962) upper Santa Fe Group
section west of Picacho Mountain (BC-3); 23S.lW.2.4323
T or C
Sample from Palomas Formation ancestral river deposits
exposed i n northern Truthor Consequences (TC-1);
13S.4W.28.211 (Sierra County)
Middle Santa Fe (Rincon
Rodey
Valley
Formation)
Two samples from middle Santa Fe Group (Rincon Valley
1.5 mi
Formation) deposits exposed south of Rodey,
southeast of Hatch(R-1,Z); 195.3W.15.344
55
EXPLANATION
25.1.6.333
0
25.1.16.111
- PLATE
1
Key Water Test Wells, with petrographic analyses
(Plates 12-15, Figures 4, 5, Table 4)
Other well-control points
e
P
Upper Santa Fe Group outcrop sample sites
(Appendix A, Part 111)
Plates 3 & 16b
Hydrogeologic sections (Plates 2-11, 16-17)
Q-43
LU-1, VI-1
CA-1
Locations of seismic refraction lines
(Reynolds & Associates, 1986, 1987)
I
Major normal faults; bar and ball on downthrown side
EXPLANATION
Informal
- PLATES
2 To 17
Hpdrostratigraphic
Unit
Units
Description
Vallep-Fill
-- Post Santa Fa Group
Deposits
RA
and floodplain deposits
of inner Mesilla
River alluvium; channel
Valley; as much as
100 ft thick. Lithofacies subdivision Iv is
component. Forms much of the "shallow
the major hydrogeologic
aquifer." Holocene to late Pleistocene.
VA
Valley-borderalluvium;tributaryarroyo(andthineolian)
deposits in areas bordering the inner Mesilla valley, with
as much as140 ft
locally extensive river-terrace deposits;
thick. Includes lithofacies subdivisions Iv and V. Most of
unit is in the unsaturated (vadose) zone. Holocene to middle
Pleistocene.
Basin-Fill
-- Santa
Deposits
Fe
Qroup
Rio Grande rift basin fill; includes alluvial, eolian, and
lacustrine deposits; with interbedded volcanic rocks (basaltp and
silicic tuffs). In the Mesilla Basin area the Santa
Fe GrouF
comprises four lithostratigraphic unitsHayner Ranch, Rinccn
Valley, Fort Hancock, and Camp Rice Formations; and locally
the major aquifere
of
exceeds 2,500 ft in thickness. It includes
the area and
is subdivided into three informal hydrostratigraphic
units:
-
of the
USF Uuuer Santa
Fe Unit; coarse- to medium-grained deposits
ancestral Rio Grande intertongue mountainward with piedmontalluvial (fan) facies, and southward with fine-grained lake and
playa sediments; volcanic rocks (mostly basalt) and sandy eolian
deposits are locally present; as much 750
as ft thick. Unit
includes the Camp Rice
(CR) and upper Fort Hancock (FH)
Formations. It also includes lithofacies subdivision Ib; of
much
facies 11, V, and VI; and parts of facies I11 and VIII. Forms
lower partof the "shallow aquifer" in the northern Mesilla
Valley, and the upper aquifer zone outside the Valley area wh2re
'much of the unit is above the water table. Middle Pleistocena to
middle Pliocene.
1
MSFMiddleSanta
Fe Unit;alluvial,eolian,andplaya-lakefacies;
interbedded sand and silt-clay basin-floor
sediments intertongue
mountainward with piedmont-alluvial (fan) deposits, and southward
with fine-grained lake and playa facies; basaltic volcanics and
1500 as
ft
sandy eolian sediments are locally present; as much
thick. Unit includes basin fill that correlates with much
theof
Fort Hancock (FH) and Rincon Valley Formations, in the Huecc
Bolson and western Jornada del Muerto (Rincon) Basin,
respectively. It also includes much of lithofacies subdivisions
111, and parts of facies 11, V, VI, VII, VI11 and IX. Forms major
part of "medium aquifer" of Leggat et al.
(1962). Middle Pliocene
to middle Miocene.
LSFLowerSantaFeUnit;eolian,playa-lake,andalluvialfacies;
sandy to fine-grained basin-floor sediments, which include thick
dune sands and gypsiferous sandy mudstone, intertongue with
conglomeratic sandstones and mudstones near the basin margin?
piedmont deposits; as much as
1000 ft thick. Unit includes basin
fill that correlates with much of the Hayner Ranch
the lower
and
Rincon Valley Formations, in the western Jornada del Muerto
(Rincon) Basin. It
also includes much of lithofacies IV X,
andand
parts of facies VII, VI11 and
IX. Forms major partof "deep
aquifer" of Leggat et al.
(1962). Middle Mioceneto late
Oligocene.
2
I
EXPLANATION
Bedrock
Units
-
and
PLATES 2 TO 17
Upper
Cenozoic
Unit
Qb
Volcanics
Description
Basaltic volcanics, mostly flows, with local cindercone and
or are interbedded with the upper
conduit material, that cap
middle Santa Fe Group. Quaternary and upper Pliocene
and
Tb
or are
Basaltic plugs and minor flows that penetrate, cap,
interbedded with the lower and middle Santa Fe Group. Miocene
Tr
Rhyolitic volcanics, with some interbedded sandstone and
conglomerate mostly ashflow tuff and lava. Oligocene
Tri
Rhyolitic igneous-intrusive complexes; mostly sills, plugs and
associated lava domes. Oligocene
Ti
Silicic to intermediate intrusive rocks. Oligocene and Eocene
Tv
Andesitic and other intermediate volcanic and volaniclastic rocks,
including lava flows and laharic breccias and mudstones. Eocene
and Oligocene
Tvi
Undivided
TVS
Intermediate volcaniclastic rocks, with minor lava flows and
intrusive units; primarily Palm Park Formation. Eocene and
Oligocene
TN
Undivided
T1
Mudstone, sandstone, and conglomerate with local gypsum beds.
Lower Tertiary, mainly Eocene
T
v
l
Undivided
K
Cretaceous rocks--undivided; includes limestone, sandstone and
mudstone.
Tx
Undivided Ti, Tv, T1,K.
w
Undivided
PU
Upper Paleozoic rocks (Pennsylvanian and Permian); includes
limestone, shale, sandstone, and mudstone, with local gypsum beds.
P
Undivided Paleozoic and Precambrian rocks the
of southern Franklin
Mountains; includes limestone, shale, sandstone, metamorphosed
sedimentary and volcanic rocks, and granite.
Rr
Tr
Tv
and intermediate intrusive rocks.
and
or Tvs
Tv
andT1
Cretaceous
and
Permian
rocks.
EXPLANATION
-
Lithofacies
Unit
PLATES 2 TO 17
Subdivisions
Description
Sand and gravel, river-valley and basin-floor fluvial facies; recent and
ancestral Rio Grande channel and floodplain deposits underlying
1) the
2 ) river-terrace surfaces-modern river-valley floor--facies Iv,
3 ) relict or buried basindeposits primarily in
the vadose zone, and
floor fluvial plains--faciesIb. The latter surfaces include theLa
Mesa geomorphic surface (Gileet al. 1981). Gravel is characterized by
of resistant rock
sub-rounded to well-rounded pebbles and small cobbles
types (mainly igneous and metamorphic) derived
in part from extra-basin
source areas.
I.
Iv.
Sand and pebbleto cobble gravel, with thin, organic-rich silty
sand to silty clay lenses; indurated zones of carbonate cementatio? rare
or absent; as much as 100 feet thick.
Ib. Sand and pebble gravel, with thin discontinuous beds and lensfes of
sandstone, silty sand, and silty clay; extensive basin-floor fluvial
facies; usually nonindurated, but with local zones that are cementad
with calcite (common), and other minerals (uncommon) including silicate
clays, iron-manganese oxides, gypsum, silica, and zeolites;
200 to 400
feet thick in central basin areas.
11.
Sand, with discontinuous beds and lenses
of pebbly sand, silty sand,
sandstone, silty clay, and mudstone; extensive basin-floor fluvial
I;
facies and local eolian deposits; gravel composition
as in facies
usually nonindurated, but local cemented zones as in facies Ib; clean
sand and pebbly-sand bodies make
up an estimated 65-85 percent of unit;
300 to 750 feet thick in central basin areas.
111.
Interbedded sand, silty sand, silty clay, and sandstone; with minor
lenses of pebbly sand and conglomeratic sandstone; basin-floor alluvial
and playa-lake facies; clay mineralogy of silty clay beds as IX;
in unit
usually nonindurated, but with local cemented zones as inIbfacies
and
11; secondary carbonate and gypsum segregations locally present in silty
10 to 40 feet
clay beds; common sheet-like to broadly-lenticular strata
35 to 65 percent of unit;
thick; clean sand layers make up an estimated
300 to 1,000 feet thick in central basin areas.
IV
V.
.
Sand to silty sand, with lenses or discontinuous beds of sandstone,
silty clay, and mudstone; eolian and alluvial facies primarily deposited
on basin floors and contiguous piedmont
slopes; nonindurated to partly
indurated, with cementing agents including calcite (common), silicste
clays, iron-manganese oxides, gyps?, and
zeolites (uncommon); cleEn
fine to medium sand makes up estmated
an
35 to 65 percent of unit; as
much as600 feet thick.
Gravelly sand-silt-clay mixtures (loamy sands
to sandy clay loams)
of sand, gravcl,
interstratified within discontinuous beds and lenses
loamy sandan silty clay; distal
to medial piedmont-slope alluvial
facies (mainly coaleascent fan deposits), with minor compoonent
of
eolian sediments; gravel primarily in
the pebble and small cobble size
range, and clast composition reflects character
of source bedrock
terrane; usually nonindurated, but with thin discontinuous layers that
are cemented with calcite; clean sand and gravel makes up an estimated
25 to 35 percent of unit; as much 600
as feet thick.
VI.
Coarse gravelly sand-silt-clay mixtures (loamy sand and sandy
l o a s to
loams) interstratified with lenses of sand and gravel; proximal tc
medial piedmont-slope alluvial facies--fan and coalescent
fan depcsits;
gravel primarily in the pebble
to cobble range (up
to 10 inches); clast
composition reflects lithologic character of source bedrock terranes;
usually nonindurated, but with discontinuous layers that are cemented
estimated 15 to 25
with calcite; clean sand and gravel lenses anmake
percent of unit; as much300
asfeet thick.
VII. Conglomeratic sandstone, silty sandstone, and mudstone with lenses and
discontinuous beds of conglomerate, sand, gravel, and gravelly sandsilt-clay mixtures (a8 in unit
V); distal to medial piedmont-slope
alluvial facies, with minor component of eolian sediments; coarse clast
sizes and composition as in unit V; moderately-well
to poorly indurated;
cementing agents include calcite (common) and silicate clays, ironmanganese oxides, silica and zeolites (uncommon); clean weakly-cemented
sand and gravel beds make up an estimated
5 to 15 percent of unit; as
much as600 feet thick.
VIII. Coarse conglomeratic sandstone and silty-sandstone, fanglomerate, and
minor lenses of sand and gravel; proximal
to medial piedmont-slope
alluvial facies--and coalescent fan deposits; coarse clast sizes a?d
compositions as in unit VI; moderately
to.well indurated; cementin'7
agents as in unit VI; moderately
to well indurated; cementing agents as
in unit VII; clean, weakly-cemented sand and gravel lenses make up an
estimated 5 to 10 percent of unit, as much as
300 feet thick.
IX.
Silty clay interbedded with thin silty sand, sand, sandstone, and
mudstone beds; basin-floor playa-lake and alluvial-flat facies; clay
mineral assemblage includes calcium smectite, mixed layer illitesmectite illite, and kaolinite (Anderholm,1985); secondary deposits of
calcite, gypsum, sodium-magnesium-sulfate salts, and zeolites are
locally present; weakly-cemented fine
to medium sand and silty sand
5-10 percent of unit; as much
as 600 feet thick in
makes up an estimated
central basinareas.
X.
Mudstone and claystone interstratified with thin sandstone and silty
sandstone beds; basinfloor playa-lakeand alluvial-flat facies; clay
mineral and non-claysecondary mineralassemblages as infacies IX:
weakly cemented fine
to medium sand and silty sand makes up an estimated
0 to 5 percent of unit; as much 600
as feet thick in central basin
area.
EXPLANATION
-
PLATES 2 To 17
Special Symbols
~
Plates 2-11, 16-17
-~
~~~
~
~~
Drill-stem packer teste, water table, and faults
Top of sampled interval
Total dissolved solids (mg/L)
P
111
I
Water table (cited literature)
High angle normal faults, with direction of relative
displacement indicated.
Plates 12-15
Lithologic Logs
LITHOLOGIC LOGS
Plates 16-17
Q-43
LU-1,VI-1
CA-1
Seismic Refraction
Lines
Locations of profiles by Reynolds & Associates
(1986, 1987)
. -
I
23.1.13.411
FIRESTATlON
SWGLE
POIN
R
a
m
LOG
0
r+-,
0
0H”METERS
0
4500
4400
4300
4200
50
0
100
r-1
Bend in Section
”
4,400
Upper Santa Fe
(USF)
50 100 150 200
4500
4400
4300
h
\+-
4,192
4200
-
4100
-
4100
4000
4000
3900
Middle Santa Fe
3900
3800
3806
I
Upper Santa Fe (USF)
3700
9
3700
7
3600
3600
0
3
34q
700
3500
3500
3400
3400
G
1
Q
0
E’
3300
3300
8
a
3200
3200
Middle SantaFe (MSF)
3100
8
3100
c3 3000
4
.
9 61
2900
510
3000
1
7
0
I
2900
6
2800
2800
M 2700
2700
Q
I2
7
1260
640‘
2600
2500
2500
W“
0
G
2600
I
2$oo
1448
I
8 37-
2400
Lower Santa Fe (LS’F)
2300
2300
2200
2200
2100
2100
,06ic-
Irv
2000
2
1900
1800
2000
Tv s
DH2,008,
1900
1800
1700
no0
1600
1600
1500
1500
Plate 2. Hydrogeologic section Las Cruces Fairground to Firestation, with borehole geophysical data.
25.1.6.333
AFTONTEST
t, NORMAL
RESIST"
CURVES
OHM-METERS
8,
t,
b
n
LL
0 10 20 3040 50
25.1.16.111
0
25.2.4.141
SAN MIGUEL
ASARCO
INDUCllON
RESIST"
CURVES
OHM-METERS
0 10 20 3040 50
2523.224
MESQUrE 2000
SINGLE
LmOLOGIC
LOG
POINT
RESlsmmY
OHM-METERS
15 30 45 60
0
4500
0 15 30 45 60
I
l
l
4500
r-
I
4400
-
4400
- 4300
4300
-
4200
-
4100
4000
-
4000
3900
-
3900
%
4200
\
4100
USF
JSF
- 3,850-
d
3
.
8
3
9
-
IV
3800
CT, 3700
03
CT,
7
3600
640
0
t
J
-
60I
3500
G
392
a 3400
_I
MSF
Q
0
507
3300
384
'
W
E
0
B
c3
598
'3I4
3200
74f
331
3100
1170
-D H 823
I476
3000
3000
_I
Q
Z
0 2900
2900
G
2800
m
2800
1
2700
MSF
Q
7
1180
I585
1052
-I
W 2600
W
LL
SF
LSF
2500
12700
400
-
2600
-
2500
-
2400
-/
2300
W"
0
3 2400
k
!
i
4 2300
2200
Tvs?
1700
580
2100
2000
2100
1200
2096
2000
- 1900
1900
LSF
LSF
1800
-
1800
-
no0
I
TVS
1700
1-
1600
1500
1600
1500
+
Plate 5. Hydrogeologlc sectlon Afton to Mesquite, with borehole geophysical data.
26.2W.l!j.433
JOHNSON
26.lW.35.131
26.lW.24.243
AFTON CONES
mocoGlc
moLouc
LOG
LOG
a,
a,
HUNT-15
WGLE
POW
RESlSTMlY
+J
OHM"€IERS
4500
4400
r-
4300
'
4200
0 10 20 30 40 50
4000
-
K
CD
@
+J
,
u
K - O H " r n S 7
U
U
0 10 30
20
40 50
-4.400 -
LL
0 10 20 30 40 50
0 10 20 30 40 50
0 lo20304050
0 10 20 30 40 50
4500
4.400
-4,195-
e-
4200
4,189
-
4100
-33SI
0 IX
3800 - ?TVS
USF
I
4000
1
3900
a
0 M 20 30 40 50
0 1020304050
4300
'4270 -
Is,
-
M
I
-
4100
27.1.4.l21
-
-3,823VF3
-v,
L
_.
3,862
3800
3700
E3
7
463
155,
3600
3600
0
f 3500
k
3500
MSF
3400
1
I
Q
0
712
'617
C
E
3400
801
716
902
'1097
>: 3
3300
I
.3,272
-
3200
3100
c3
3000
e
-I
'I 288
2900
m
2800
e
LSF
3200
3100
KP
3000
El
G
z
KP
DH631-
Middle Santa Fe
(MSF)
I134
Q
7
0
3900
MSF
3700
c]
-
2900
t
LSF
2800
I
ZOO
Q
I 533
'6664
bW
2600
7
2500
1
2600
Trv
L
L
1571
'MSF
378
I0
N
1
T
2500
1787
1238
CI
"ITrv
Lower Santa Fe
(LSF)
2300
I
1J
Trv
2400
61
= t
+
2200
2100
B
LSF
2000
1900
- 0 )
-
.->
cn
1
3
1800
a00
L
tJ
.-c
Kp
Trv
Trv?
1600
1500
Plate 4. Hydrogeologic section Aden to La Tuna, with borehole geophysical data.
LL
0 10 20 30 40 50
0 10 20 30 40 50
4500
1
1
1
0 50 100 150 200
0 1020304050
0 10 20 30 40 50
0 10 20 3040 50
0.10 20
0
3040 50
1
100
200
300
400
I
I
I
1
500
4500
4400
4400
4300
4300
4200
I
4200
4100
4100
4,023
4000
4000
3900
3900
J
R
a
3800
a
3700
E2
c
MSF
-
bH 320
5
3600
195
0
3700
KP
7
3600
3800
603
3500
3500
3400
3400
Q
-I
Q
0
150
52 3
3300
’
3300
E
3100
8
-1
3200
5200
3000
Q
Z
0 2900
1
1
540
304
Middle Santa Fe
3100
MSf
3000
2900
G
W
Bm
2800
2800
Ti/ KP
ZOO
Q
2700
2600
2600
Lf
z 2500
2500
W”
n
2400
2400
4
2300
2300
2200
2200
no0
no0
T
2000
2000
Lower Santa Fe
1900
LSF
1900
1800
1800
woo
wo
1600
1600
Trv?
I
‘1500
Plate 5. Hydrogeologic section La Union to Vinton, with borehole geophysical datu.
I
I
I
1500
28.3.32.143
0
STATERESAtl
t' NORMAL
JL-4-2-203
Q-I59
moLoGyc
2 OR H%Mg -FM ~ S
a
0 10
30 20
40 50
0 10 20 30 40 50
LOG
~
loG
0 10 20 30 40 50
4500
4500
4400
4400
4300
4300
4200
4200
4100
"""".
4100
"
"
"
"
Upper Santa Fe
(USF)
4000
4000
c
-
3900
3800
a
UllL
k
3800
3700
E2
3900
3700
7
3600
0
3 3500
2
k
-I
523
91 I
I
3600
Midd'le Santa Fe
MSF'
3500
(MSF)
t
3400
Q
0
E'
799
'1516
DM700 -
3400
3300
3300
Ea
3200
3200
1984
3lOO
3 557
3100
0
w
c3
Q
3000
I
'
MOO
'
_I
Z
0 2900
2900
@
*
2800
m
2700
2800
Lower Santu Fe
(LSF)
Q
2600
z
2600
,
T
V
i
LI
WOO
woo
2500
W"
gn
2400
T.v i
5
2400
2300
!300
'2200
E?oo
2100
?IO0
MOO
!OOO
1
'
1900
900
1800
so0
Ti, TL
n00
i,Tl
1600
700
Ti, KP
1500
600
500
Plate 6. Hydrogeologic section Noria Test to Mesa Boulevard, with borehole geophysical data.
29.1w.6.410
HUNT-1485
LITHOLOGIC
LOG
LOG
20
"4.230
LOG
LOG
DEkiaEES
CELSIUS
40
29.lw5.4ll
Hum-lan
TEMPERATURE
S.W.~I
Hum=-lav
UTHOu)GIC
mw.6.410
HUNT-t485
TEMPWATURE
ea
ze.lw.5.411
HUNT-14V
SINGLE POINT
RESISTIVITY
OHM-METERS
DEGREES
CELSIUS
20
40
60
a la
20 30 40 50
29.W.3.344 29.W.3.344
HUNT-I~I~
LITHOLOGIC
HUNT-IOI~
TEMPERATURE
LOG
LOG
DEGREES
CELSIUS
20
40
60
-
m
KP
"
"
Middle Santa Fe
Lower Santa Fe
KP
-DH2..000
-
KP
Plate 7. Hydrogeologic section Potrillo Mountains to Noia Test, with borehole geophysical data.
m
0
m20304O!xJ
/i
Bendin
4400
0 10 20 30 4 0 50
*0°
1
r"
4500
Section
(400
4300
4500
4200
4,189
-
4200
I 4100
4100
USF
4000
4Ooo
3900
3900
L
3800
-
Fx
3800
3700
1
i
3700
3600
3600
0
3
3500
MSF
'Q
*
-I
3400
6
0
3500
M.iddle Santa
( MSF)
3400
'I
3300
902
I
'
E
IO97
5300
!
3200
3100
8,
3100
"
0
3200
1134
'1288
3000
3000
LSF
29oc)
..
.
Lower Santla
2800
I
2700
28Ob
z
2500
2500
W-
n
E
M O
2400
2300
2300
2200
2200
no0
a00
2000
2000
1900
1900
1800
la00
1700
It-I
no0
I
,
1600
Ti,
i-
1600
1500
1500
Plate 8. Hydrogeologic section Afton Test to Noria, with borehole geophysical data.
25.1.6.333
cv
24.1.8.123 23.1.30.422
Q, LAS CRUCES-36
+
SINGLE
POINT
RESlSTNrrY
RESISWTW
OHM-MEWS
WEST MESA
SINGLE
POINT
2
0
50
100
4500
4400
0
Q, AFTON TEST
50 150
100
5
a
NORMAL
RESISWTW
CURVES
OHM-M€I'ERS
- "7
OHM-MmRS
27.1.4.Pl
n
7
2010
30 40 50
0 102030
N
m
F
RESlsmmY
CURVES
00
8
NORMAL
RESlSTMlY
0 1020
0 1020
30 40 50
30 40 50
CD
28.2.25.233
STA TERESA 9
NORMAL
RESlsmmY
CURVES
OHM-METERS
CURVES
OHM-METERS
OHM-METERS
0 10
20 30 40 50
4050
28.3.32.143
27.1.10.100
NMSU TEST
0 10 2030
40 50
STATERESA11 Q>
+a
NORMAL
RESIST[VITY
CURVES
OHM-METERS
0 10 2030
E
40 50
&OO
1
r
4400
4300
4300
4200
"4,192
-
-4.203
-
-4,228"
-
-4,189
T bJI
-
4100
4000
a
"
'LTJ
Uppe r Sa nta Fe
(USF)
-
4200
-4,165
-"
"""".
-4.165
"4,112
-
,"_""
Upper Santa Fe
(USF)
I
4000
3900
3900
3800
3800
3700
~
3500
k
HI
3400
Ix
Viddle Santa Fe
(MSF)
l
W
Q
3200
3100
-DDH950
OH 1,010
-
3700
3600
i
3500
MSF
"DH700
m
Q
*-rz
.'.-
I
M i d d l e Santa Fe
(MSF)
"
0
F 3300
c1c
E
I
USF
0
>
4100
"I,
3600
1
-
L
."""-7
.""~
"_"""""".
D
7
2
2
-,4,095
VlSF
3400
3300
-
3200
3100
8
c3
1
3000
3000
Q
Z
0 2900
Q=
Q
2
Lower Santa Fe
(LSF)
2800
zoo
E
LSF
2800
I
-DH 1.565 -
Tv i
Lower Santa Fe
( L S F)
LSF
-DH1,50-
2600
2900
i66r
2700
2600
LS F
2500
2500
6
2400
2400
4
2300
w"
Q
2
Trv
- 2,3.00-
LSF
Ti, TL
-
Trv
Tr v
2300
Tv
TI,
2200
2200
2100
2100
t
or
2000
basal
1900
LSF?
1800
-"
-D.H2,470-
"
'
Tvs
I
1600
1500
Plate
~9.
Tv 1
1900
1800
zone
I700
TiJKP
Trv
O H 21,759
2000
midbasi n
lfault
1700
I
I
Hydrogeologic section 'Las Cruces to Santa Teresa, with borehole geophysical data.
1600
1500
cv
M
23.1.13.411
FlRESUiTON
23.2.30.243
LAS CRUCES 800
0 ma
+
0 POW
m
s
T
M
T
Y
OHM"€IERS
SINGLE
POW
-
RRlslMly
OH""
0 25 50 75 100
0 200
50
150100
0 10 20 30 40 50
0
75 1Jo 225 300
0 15 30 45 60
U
0
15 30 46 60
0 0
4400
4300
4300
4mo
4200
4100
4100
4000
4000
3900 -3,892
IV
-
L
g!jo
3900
-3,878
RA
-4
3800
lRiver alluvium(R4-
3,860 -
Iv
13;
450C
SY
3700
Upper Santa Fe
(USF) .
7
.
r
3600
0
240
700
657
e
-1
404
507
384
3300
3300
3200
3100
JlSF
0 2900
'1
DH809-
-I
Middle Santa Fe
1 m,II
59
314
MSF
p6 I
'510
8
3200
,675
494
74!
730
1
639
- DH823 -
3000
Q
M SF
c
3100
3000
2900
G
Middle Santa Fe
(MSF)
2800
2800
2700
Q
2600
I80
400
1260
'640
120(
MSF
LI
z 2500
w"
n
3 2400
4
3400
p37
K
-T
1460
Z
5
3500
430
8
a
MSF
392
3400
fJ
3600
298
3
39
3500
Q
E>
3800
River alluvium (RA)
3700
f
0 10 20 3040 50
4500
0 15 50 45 60
.SF
I
152(
2600
2500
448
937
2400
LSF
2300
2300
2200
2200
700
no0
2000
1900
2100
i80
Tr v
LSF
L SF
Lower Santa Fe
(LSF)
1800
2Ooo
1900
1800
woo
woo
1600
1600
Trv
1500
1500
Plate IO.Hydrogeologic section Las Cruces Firestation to Vado, with borehole geophysical data.
0
F
+
leb
26.3.33.212
OLQUIIT FARMS
NORMAL
RESIST"
CURVES
OHM-METERS
25.3.28.434
VADO
NORMAL
RESISTMTY
CURVES
OHM-METERS
0 10 20 30 40 50
0 10 20 30 40 50
JL-49-04-113
" JL-49-04-109
3r ~ r RMsmmY
NQoc
(2-197
NORMAL
RESISTMTY
t
?
CURVES
CURVES
OHM-METERS
CURVES
OHM-METERS
0 10 20 30 40 50
JL-49-04-433
Q6-3
NORMAL
0 10 20 30 40 50
OHM-MEIB?S
m
Q,
u
RESISrrmrI
CURVES
0H"METERS
LOG
OHM-METERS
02010
4500
0 10 2030
30 40 50
4300
4300
4200
4200
4100
4100
.
-3,997
River alluvium (RA)
-3,800
-t
.
DJ
49
,3680
25
170
!33
312
110
J
k
313
320
5.29
MSF
a
3400
-1
3300
E3
'
k
565
3200
3100
8
'30
MiddleSanta
(MSF)
'IO
Fe
586
846
LSF
2800
0 50
I-
H 1,050-
558
2700
Q
""
HI,I7
k
-DH1,212
-
II70
1300
3,757
River a1I uvi um(RA)_ - Iv
385
601
!6D
800
M SF
M SF
Middle Santa Fe
(MS F)
3400
4@
47 52
"
"
970
3140
3300
MSF
532
3200
-
367
365
319
334
679
r15
1
354
Lower Santa Fe
LS F
-
357
265
/
3100
-OH
LS F
1,004-
2900
LSF
2800
007
K
1542
Ti, TL
-
-
K
3000
8 5t
2400'
2,817-
-0H1.074
11.16
27d
L
t
-
1057
2500
3500
506
615
737
3700
523
3 45
405
I I94
-
360
418
%
no0
2600
LSF
-
2500
Ti
W"
c1
4
7 24
739
0 2900
g
'71
428
320
-
3800
3600
,57
576
376
747
RA
275
513
39
3000
-
- 3,768-
- 3.0 03-
184
507
$95
$44
675
707
;I4
___ps
394
$26
697
366
67 0
Q
Z
m
88
c31
r
0
2 3500
4000
"
-
(T) 3700
3600
-
"""_.
3900
ISF
Y0
I
"
40 50 0 10 20 30 40 50
4400
3800
-1
OHM-METW
a,
cl
7
s,
4400
3900
F
LmRI3
NORMAL
4500
4000
Q
0
(0
28.3.n.111
Q-144
NORMAL
Q-138
rn0LOGIC
-
E
0 10 20 30 40 50
0 10 20 30 40 50
LlPPlNCOll
NORMAL
i-J
28.3.34.331
JL-49-04-723
JL-48-04-421
Q-202
2400
f
2400
2300
2200
2100
2000
K,.?
i
no0
2200
LSF
2100
Lower Santa Fe
>
(LSF)
WOO
1800
2300
K
t
Ti,KF
2000
1900
i
1800
Tn
3
KP
no0
KP
1600
1600
E00
1500
Plate 11. Hydrogeologic section Vado to Lizard, with borehole geophysical data.
*
LITHOLOGIC LOG
GEOLOGIC UNITS
RESISTIVITY
CURVES
OHM-METERS
4200
0 10 20 30 40 50
4209
PERCENT
PERCENT
0
25
0
50 100
75
25
50 100
75
420 0
L
4100
4100
._-"_
""
*..
.--"""
----- -
e
4000
4000
"""""""F
"_""
I-
"_
3900
"".
""
3900
3800
3800
3700
3700
3600
3600
h-
3500
3500
3
3400
3400
1 3300
3300
a
cu
03
.
i
"
0
t
k
n
Q
0
F
W
3200
3200
>
3100
n
8
3000
3000
c>
_I
-7
2900
0
%
2800
7
t
2900
1
+ + + + + + + + +
2800
W
&
2700
2700
2600
2600
2500
2500
2400
240 0
m
Q
W
W
LL
7
W-
n
3
64
2300
2200
2100
2000
1900
1800
1700
+ + + + + + + +
~
+
~
~
~
+ + + + + + + +
+ + + + + + + +
+ + + + + + + +
+ + + + + + + +
+ 77/27
+ + + + + + + + +
+ + . + + + + + +
+ + + + + + + + +
+ + + + + + + +
T + + + + + + + ?
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
A + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
- + + + + + + + + + + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + +
- + + + + + + + + + + + + + + + + +
.+ + _ t + + + + +
I
Plate 12. Geoloqical data on Afton test well.
J
~
2300+
2200
2100
2000
1900
1700
~
6
d
0
0
0
0
0
0
G
0
G
0
0
6
0
G
0
N
0
0
0
0
0
0
h)
0
0
Y
0
Y
0
0
0
h)
N
0
E
0
w
0
N
w
0
0
0
0
0
%!
0
0
0
0
0
!2
E
0)
0
0
ul
10
0
0
N
0
0
Fi
gz
22
0
0
c:
0
0
0
8
0
0
0
P
0
0
w
ul
0
0
w
0
0
0)
GI
OF 1929
Y
0
0
0
0
m
w
M
0
0
I
u\
,)
0
0
0
0
w
0
0
0
N
w
0
0
w
w
0
0
w
P
Lrl
ul
0
0
0
0
a
w
0
3
0
0
m
w
Fort Hancock Fm
k!
0
0
9
w
w
Hydrostrat. Unit
0
0
0
GI
Middle Santa Fe Hydrostratigraphic Unit
0
0
N
u3
Lower Santa Fe
0
0
m
N
ALTITUDE, IN FEET ABOVE NATIONALGEODETICVERTICALDATUM
h)
0
8
0
f
0
0
0
0
(D
Lrl
0
8
0
0
f
0
Upper 'SantaFe
i
I Hydrostrat, Unit
,! Camp
\ Rice Fm
I
0
u3
0
w
0
ie
0
0
ie
0
"
0
0
cn
0
P
0
w
0
N
0
3
0
GEOLOGICUNITS
WHIC
FRAGMENT
COMPOSEION
LITHOLOGICLOG
0
4200
4100
I
Cam
EpkrE
Jpper Santa FI
10
20
30 40
50
0
25
50 100
75
7
PERCENT
PERCENT
0
25
50 100
75
1.200
VRF
SRI
1.100
,..__
..
...
._..
..:..
. :......
.:
.......
.I.. ..>:::
.._.:.* ;.: .
4000
1.000
lydrostrat. Uni
3900
3900
3800
3800
3700
3700
3600
3600
k 3500
3500
m
cu
m
7
0
2
2
%
D
3400
3400
1
1 3300
Q
0
F
Y
O
t-
3300
3200
3200
3100
3100
3000
3000
W
n
8
(3
I
1
4
Z
2900
2900
0
%
2800
7
2800
W
&
2700
2700
2600
2600
2500
2500
2400
2400
m
Q
+
W
W
LL
-
W-
n
3
6
2300
c.
.C
2300
3
2200
2200
2100
2100
2000
2000
1900
1900
1800
1800
1700
1700
Plate 14. Geological data on La Union test well.
LITHOLOGIC
GEOLOGIC
UNITS
LOG
PERCENT
0 10
20
30 40 50
0
25
50 100
75
4200
I127
1 4
4100
PERCENT
0
25
50 100
75
URF
4200
SR
4100
d
4000
"
"
"
4000
3900
3900
3800
3800
3700
3700
3600
3600
LL
3500
3500
3
3400
3400
1 3300
3300
3
7
0
3
G
n
4
0
F
3200
3200
O
3100
3100
8
c3
3000
3000
2900
2900
W
>
E
n
A
<
Z
0
%,
2800
7
t
W
&
2800
2700
270 0
2600
2600
2500
2500
2400
2400
4 2300
2300
m
Q
W
W
LL
7
W-
n
3
t
5
I
2200
2200
2100
2100
2000
2000
1900
1900
1800
1800
1700
1700
Plate
15. Geoloqical data
J
on Noria test well*
-d g
3
u
Valley
mk
m
Mesilla
W
-4:
16a
-
V,III
J-v
IV
Ill
I
3
-
'I
2,500 -
VII,X
..
" -1;
X,IV
0
e.
- 3,000
A
MSF
LSF
- 2,500
MSF
LSF
LSF
MSF
LSF
".
VII,IV
"
.
i
3
X,IV
\
aJ
m
Tvs
+
._
L
*
c
IIITvs
I
N
I
mid-basin uplift
I
-
<-.
<.-
Tvs
I
6
10 mi
- 3,500
USF
LSF
northwestern sub-basin
1,000
11b
i,
i'
Ill
Tvs ? or
?basal LSF (X,VII)?
2,000 -
1,500-
1
- 4,000
MSF
Ill
1
LSF
v)
I
MSF
VI
VII,IV
-
MSF
"2
p!
RA
III USF
k - 7 . - -5
USF
7 4
ZNO.
'
<.
""
VII,IV
:.
g:
11,111
2
V,II
I "-A"
- - -- - -
LSL
""_"
e
a'v.
USF
I
I -
"
"
"
T'v.
Ib,lll
4 - 4,500
m-
aJcy
2
0
_
9
'Jp!
tI
I
l,111
3,500 -
La Mesa
I"
Ib,ll
"SF
-"V"
c
.
o
w
a N
4,000 "_""
USF
3,000 -
E
0
;
:
C
Mesilla
-
jl
0.7
.0 +
w
o
NO.
4,209
Valley
L
m d
- 2,000
IV,VII
LSF
- 1,500
Trv
fsFF
Plate 3
eastern (La Union-Mesquite) subbasin
3
m
I
I
I
5
1,000
I
I
10 mi
>
16c
4,500
>
Y
4,500
-1
5
=4
4,270
1,111
4,000
4,000
'3,862
clx,II
,
'X(Tvs?)
-3,500
KP
3,500
.3,000
3,000
KP
2,500
-2,500
2,000
- 2,000
1,500
- 19500
east
Potrillo
uplift
.l,OOO
1,000
Mesilla Valley
O
h
c
m
N
m
16d
7
7
4,500
4,023
4,000
3,500
3,000
""2,500
-=""
2,000
1,500
I
eastern (Lo Union-Mesquite) subbasin
I
1
1,000 I
0
I
I
2
3
I
Itu-].
,
Plate 5
VIL
I
I
I
I
4
5
6
7 mi
I500 rn
-
..
m
0
N
x
".
16e
P
4,500 -_
3
4,230 --
%
0:
N
m
t
'v.
'v.
7
3
7
,II
Mesilla Valley
4,500
2
I
I
c!
cy
4,000
-111
_"
x
-
3,500 -
KP
3,000 -
-"\-----< III,IX
'\
MSF
L"-
LSF
IX,III
IX,III
IX,III
MSF
"
LSF
3,000
MSF
LSF
x, IV
I?
Tvi
2,500
Ti,TL
.c
e
c
0
+
-
:I
Et
;
0,
-
2,000
r
-
500
a
2.
>
n
0
1,500 -
IO00
K
L
"
"
m
2,000 -
3,500
Ti
I
2,500 -
1,500
-.2
Franklinuplift
I
"
0
I
I
Ti,KP
Cristo Rey uplift
Ti,KP
PI'
1,000
4,075
4,000
a
L
111,11
I
I
20
1
I
1
Plate 6
I
I
I
25
26
'
1,000
mi
Horizontal Scale
1 :100,000
-
Vertical exaggeration
lox
I
0
I
I
2
I
I
4
I
I
6
I
I
8
I
.O
km
Plate 16. Hydrogeologic Sections of the Mesilla Basin, Las Cruces to El Paso Area, showing inferred distribution of major hydrostratigraphic and lithofacies units,
and fault zones
J T W. Hawley and R. P. Lozinsky, 1992
NMBM&MR Open-file Report 323
17a
.4,500
4,500
.4,000
4,000
'3,500
3,500
"
"
"
-
VI
c-,
III,V
'3,000
VII,IV
2,500
"
2,000
"X,IV
""""-
-2,500
1
a
,
"X"
VII,
'2,000
2
1
Trv
t
-
3
'1,500
1,500
Ti.K
,
.1,000
0
17b
4,500
'4,000
-
3,500
3,000
.2,500
- 2,000
. 1,500
. 1,000
35 mi.
- 5,000
I500 rn
I
.'
17 c
- 4,500
La Mesa
- 4,000
4,000
"""""_
3,500
"
- 3,500
1000.
'
"
"
3,000
- 3,000
--------
---""""
- 2,500
2,500
Tr
- 2,000
2,000
----horizontal scale
""_"_
1,500
1:100,000
vertical exaggeration
-lox
Tv L
Trv
mid-basin uplift
1,000
0
5
10
Tv L
1
15
,500
Ti,TL?
Ti,KP?
Tv L
Tv
Plate 8
mid-basin uplift
I
I
I
.
I
.
I
20 mi.
I
0
I
2
I
I
I
4
1
I -
6
- 1,500
- 1,000
I
8
.O
I km
Plate 17 Hydrogeologic Sections of the Mesilla Valley and west central Mesilla Basin areas, showing inferred distribution of major hydrostratigraphic'and lithofacies units,and fault zones
,JI W. Hawley and R. P. Lozinsky, 1992
.NMBM&MR Open-file Report 323