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Mark W. Bultman

Publications and source records attributed to Mark W. Bultman.

15 recordsLinked to original sources
USGS2023

Geologic map and hydrogeologic investigations of the upper Santa Cruz River basin, southern Arizona

This report includes an updated geologic map and cross sections of the upper Santa Cruz River basin, southern Arizona. The map and cross sections describe the geometry, thickness, and structure of the Miocene to Holocene units which form the main aquifers in the basin. The report also includes results of new hydrogeologic studies including (1) mapping and defining depth to bedrock based on geophysical data in the map area to better define the geometry and structure of the basin aquifers, (2) describing newly recognized hydrologically significant faults in the Peck Canyon and Sopori Wash areas, and (3) evaluating groundwater sources and hydrogeology of the Potrero Creek wetlands.

Arizona↗
USGS2018

Geologic framework and hydrogeology of the Rio Rico and Nogales 7.5’ quadrangles, upper Santa Cruz Basin, Arizona, with three-dimensional hydrogeologic model

Rapid population growth and declining annual recharge to aquifers in the upper Santa Cruz Basin area of southern Arizona, have increased the demand for additional groundwater resources. This demand is predicted to escalate in the future because of higher temperatures, longer droughts, less aquifer recharge, and decreased river and stream base flow. We conducted geologic studies to help evaluate and better understand groundwater resources in the basin. Results of these studies are presented in this report, which summarizes the basin geologic framework and hydrogeology, and presents a threedimensional (3D) hydrogeologic model for the Rio Rico and Nogales 7.5′ quadrangles. Three major hydrogeologic units are displayed in the 3D model; a lower basement confining unit, consisting of Jurassic, Cretaceous, and Tertiary (Paleocene and Oligocene) rocks; a middle unit composed entirely of the Miocene Nogales Formation; and an upper unit consisting of late Miocene to Holocene surficial deposits. The Nogales Formation and the late Miocene to Holocene sediments are the main aquifers in the upper Santa Cruz Basin. The 3D model integrates the hydrogeologic units and faults to define the geometry, structure, and thickness of the aquifer system that provides water to Nogales and surrounding communities of southernmost Arizona. The report includes an EarthVision 3D Viewer, consisting of software enabling the user to view data interactively in 3D space to help explain the internal complexities of the basin geometry, structure, stratigraphy, and hydrology. The 3D model is a synthesis of geologic data from geologic maps, cross sections, and lithologic descriptions and interpretations; and geophysical data including gravity, magnetic data, and airborne electromagnetic data.

Arizona↗
USGS2016

Bedrock morphology and structure, upper Santa Cruz Basin, south-central Arizona, with transient electromagnetic survey data

The upper Santa Cruz Basin is an important groundwater basin containing the regional aquifer for the city of Nogales, Arizona. This report provides data and interpretations of data aimed at better understanding the bedrock morphology and structure of the upper Santa Cruz Basin study area which encompasses the Rio Rico and Nogales 1:24,000-scale U.S. Geological Survey quadrangles. Data used in this report include the Arizona Aeromagnetic and Gravity Maps and Data referred to here as the 1996 Patagonia Aeromagnetic survey, Bouguer gravity anomaly data, and conductivity-depth transforms (CDTs) from the 1998 Santa Cruz transient electromagnetic survey (whose data are included in appendixes 1 and 2 of this report). Analyses based on magnetic gradients worked well to identify the range-front faults along the Mt. Benedict horst block, the location of possibly fault-controlled canyons to the west of Mt. Benedict, the edges of buried lava flows, and numerous other concealed faults and contacts. Applying the 1996 Patagonia aeromagnetic survey data using the horizontal gradient method produced results that were most closely correlated with the observed geology. The 1996 Patagonia aeromagnetic survey was used to estimate depth to bedrock in the upper Santa Cruz Basin study area. Three different depth estimation methods were applied to the data: Euler deconvolution, horizontal gradient magnitude, and analytic signal. The final depth to bedrock map was produced by choosing the maximum depth from each of the three methods at a given location and combining all maximum depths. In locations of rocks with a known reversed natural remanent magnetic field, gravity based depth estimates from Gettings and Houser (1997) were used. The depth to bedrock map was supported by modeling aeromagnetic anomaly data along six profiles. These cross sectional models demonstrated that by using the depth to bedrock map generated in this study, known and concealed faults, measured and estimated magnetic susceptibilities of rocks found in the study area, and estimated natural remanent magnetic intensities and directions, reasonable geologic models can be built. This indicates that the depth to bedrock map is reason-able and geologically possible. Finally, CDTs derived from the 1998 Santa Cruz Basin transient electromagnetic survey were used to help identify basin structure and some physical properties of the basin fill in the study area. The CDTs also helped to confirm depth to bedrock estimates in the Santa Cruz Basin, in particular a region of elevated bedrock in the area of Potrero Canyon, and a deep basin in the location of the Arizona State Highway 82 microbasin. The CDTs identified many concealed faults in the study area and possibly indicate deep water-saturated clay-rich sediments in the west-central portion of the study area. These sediments grade to more sand-rich saturated sediments to the south with relatively thick, possibly unsaturated, sediments at the surface. Also, the CDTs may indicate deep saturated clay-rich sediments in the Highway 82 microbasin and in the Mount Benedict horst block from Proto Canyon south to the international border.

Arizona↗
USGS2016

Hydrogeologic investigations of the Miocene Nogales Formation in the Nogales Area, Upper Santa Cruz Basin, Arizona

Hydrogeologic investigations were conducted to evaluate the groundwater resource potential for the Miocene Nogales Formation in the Nogales area, southern Arizona. Results indicate that parts of the formation may provide new, deeper sources of groundwater for the area. Geologic mapping determined the hydrogeologic framework of the formation by defining lithologic, mineralogic, and stratigraphic characteristics; identifying potential aquifers and confining units; and mapping faults and fractures which likely influence groundwater flow. Geophysical modeling was used to determine the basin geometry and thickness of the Nogales Formation and younger alluvial aquifers and to identify target areas (deep subbasins) which may prove to be productive aquifers. Volcaniclastic sandstone samples from the formation were analyzed for porosity, bulk density, saturated hydraulic conductivity, and fabric. Effective porosity ranges from 16 to 42 percent, bulk density from 1.6 to 2.47 grams per cubic centimeter, and saturated hydraulic conductivity (SHC) from 4 to 57 centimeters per day (4.9×10 -5 to 6.7×10 -4 centimeters per second). Thin sections show that sandstone framework grains consist of quartz, feldspar, biotite, hornblende, pumice, volcanic glass, and opaque minerals. The matrix in most samples consists of pumice fragments, and some contain predominantly silt and clay. Samples with a mostly silt and clay matrix have lower porosity and SHC compared to samples with mostly pumice, which have higher and wider ranges of porosity and SHC. Pore space in the Nogales Formation sediments includes moldic, intercrystalline, and fracture porosity. Some intercrystalline pore space is partially filled with calcite cement. About one third of the samples contain fractures, which correspond to fractures noted in outcrops in all members of the formation. Scanning electron microscope (SEM) and x-ray diffraction (XRD) analyses indicate that most of the samples contained the zeolite clinoptilolite and mixed-layer clay. X-ray diffraction analyses verified clinoptilolite as the only zeolite in Nogales Formation samples; they also verified the presence of smectite and illite clay and some kaolinite. Samples which contain greater amounts of clinoptilolite and lesser amounts of smectite have high porosity and SHC in narrow ranges. However, samples with abundant smectite and lesser amounts of clinoptilolite span the entire ranges of porosity and SHC for the formation. All members of the Nogales Formation are fractured and faulted as a result of Tertiary Basin and Range extensional deformation, which was broadly contemporaneous with deposition of the formation. These structures may have significant influence on groundwater flow in the upper Santa Cruz basin because, although many of the sediments in the formation have characteristics indicating they may be productive aquifers based only on porous-media flow, fracturing in these sediments may further enhance permeability and groundwater flow in these basin-fill aquifers by orders of magnitude.

Arizona↗
USGS2016

Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona

The Rio Rico and Nogales (Arizona) 1:24,000-scale quadrangles are located in the Basin and Range Province of southern Arizona, and the southern edge of the map is the international border with Sonora, Mexico. The major urban area is Nogales, a bi-national city known as “the gateway to Mexico.” Rocks exposed in the map area range in age from Jurassic through Quaternary. Major physiographic, geologic, and hydrologic features in the map area include the southern San Cayetano Mountains, Grosvenor Hills, and Sonoita Creek in the northern part, and Mount Benedict and the Mount Benedict horst block in the southcentral part. The horst block is bounded by the Santa Cruz River on the east and Nogales Wash on the west. The objectives of our mapping were to define the geologic framework for the Nogales area and the upper Santa Cruz basin to support ongoing multidisciplinary projects. This new work will improve understanding of the Nogales Formation to more fully assess its groundwater resource potential. We significantly revised the Miocene Nogales Formation based on geologic mapping combined with new geochronologic, geophysical, and petrographic studies.

Arizona↗
USGS2015

Detailed interpretation of aeromagnetic data from the Patagonia Mountains area, southeastern Arizona

The induced magnetic field and the remanent magnetic field of rock masses are important to geologic modeling based on Earth’s magnetic field data. The orientation of the induced magnetic field is approximately parallel to the orientation of Earth’s geomagnetic field and its intensity can be derived from measured magnetic susceptibilities of rocks in a study area. The orientation and intensity of the natural remanent magnetic field is much harder to determine; therefore, few investigators have included magnetic remanence as a contributing factor to studies of continental magnetic anomalies. All rocks have remanent magnetism and, in intrusive or volcanic rocks, this component of the total magnetic intensity of the Earth’s magnetic field can be as large as or larger than the induced component. The Patagonia Mountains in southeastern Arizona were selected to produce a subsurface geologic model from aeromagnetic data by incorporating physical properties of rock including measured magnetic susceptibilities, estimated remanent magnetic field orientations and intensities, a known association of intrusive events, and information from existing geologic mapping. The result is a model of geology at depth that may better represent reality than previous poorly substantiated cross sectional models. This new model includes concealed intrusive rocks and defines areas where concealed mineral deposits may be found. It also shows that volcanic rocks might occupy basins at relatively shallow depths in basins with low aeromagnetic anomalies. Euler deconvolution depth estimates derived from aeromagnetic data with a structural index of 0 show that mapped faults on the northern margin of the Patagonia Mountains generally agree with the depth estimates in the new geologic model. The deconvolution depth estimates also show that the concealed Patagonia Fault southwest of the Patagonia Mountains is more complex than recent geologic mapping represents. Additionally, Euler deconvolution depth estimates with a structural index of 2 locate many potential intrusive bodies that might be associated with known and unknown mineralization.

Arizona↗
USGS2014

Magnetic susceptibility data for some exposed bedrock in the western conterminous United States

In-place rock magnetic susceptibility measurements for 746 sites in the western conterminous United States are reported in a database. Of these 746 sites, 408 sites are in the Silverton Caldera area of the San Juan Mountains of southwestern Colorado. Of the 408 sites in the Silverton Caldera area, 106 sites are underground. The remaining 338 sites outside the Silverton Caldera area were on outcropping rock, are distributed from southern Arizona to northwestern Wyoming, and include data from California, Nevada, Utah, Colorado, and New Mexico. Rock-density measurements are included for some sites. These data have been collected by various U.S. Geological Survey studies from 1991 through 2012 and are intended to help improve geophysical modeling of the Earth’s crust in the Western United States. A map-based graphical user interface is included to facilitate use of the data.

Arizona, California, Colorado, Nevada, New Mexico,↗
USGS2013

Investigation of the structure and lithology of bedrock concealed by basin fill, using ground-based magnetic-field-profile data acquired in the San Rafael Basin, southeastern Arizona

Data on the Earth’s total-intensity magnetic field acquired near ground level and at measurement intervals as small as 1 m include information on the spatial distribution of nearsurface magnetic dipoles that in many cases are unique to a specific lithology. Such spatial information is expressed in the texture (physical appearance or characteristics) of the data at scales of hundreds of meters to kilometers. These magnetic textures are characterized by several descriptive statistics, their power spectrum, and their multifractal spectrum. On the basis of a graphical comparison and textural characterization, ground-based magnetic-field profile data can be used to estimate bedrock lithology concealed by as much as 100 m of basin fill in some cases, information that is especially important in assessing and exploring for concealed mineral deposits. I demonstrate that multifractal spectra of ground-based magnetic-field-profile data can be used to differentiate exposed lithologies and that the shape and position of the multifractal spectrum of the ground-based magnetic-field-profile of concealed lithologies can be matched to the upward-continued multifractal spectrum of an exposed lithology to help distinguish the concealed lithology. In addition, ground-based magnetic-field-profile data also detect minute differences in the magnetic susceptibility of rocks over small horizontal and vertical distances and so can be used for precise modeling of bedrock geometry and structure, even when that bedrock is concealed by 100 m or more of nonmagnetic basin fill. Such data contain valuable geologic information on the bedrock concealed by basin fill that may not be so visible in aeromagnetic data, including areas of hydrothermal alteration, faults, and other bedrock structures. Interpretation of these data in the San Rafael Basin, southeastern Arizona, has yielded results for estimating concealed lithologies, concealed structural geology, and a concealed potential mineral-resource target.

Arizona↗
USGS2005

Candidate-penetrative-fracture mapping of the Grand Canyon area, Arizona, from spatial correlation of deep geophysical features and surficial lineaments

Some aquifers of the southwestern Colorado Plateaus Province are deeply buried and overlain by several impermeable shale layers, and so recharge to the aquifer probably is mainly by seepage down penetrative-fracture systems. The purpose of this 2-year study, sponsored by the U.S. National Park Service, was to map candidate deep penetrative fractures over a 120,000-km2 area, using gravity and aeromagnetic-anomaly data together with surficial-fracture data. The study area was on the Colorado Plateau south of the Grand Canyon and west of Black Mesa; mapping was carried out at a scale of 1:250,000. The resulting database constitutes a spatially registered estimate of deep-fracture locations. Candidate penetrative fractures were located by spatial correlation of horizontal- gradient and analytic-signal maximums of gravity and magnetic anomalies with major surficial lineaments obtained from geologic, topographic, side-looking-airborne-radar, and satellite imagery. The maps define a subset of candidate penetrative fractures because of limitations in the data coverage and the analytical technique. In particular, the data and analytical technique used cannot predict whether the fractures are open or closed. Correlations were carried out by using image-processing software, such that every pixel on the resulting images was coded to uniquely identify which datasets are correlated. The technique correctly identified known and many new deep fracture systems. The resulting penetrative-fracture-distribution maps constitute an objectively obtained, repeatable dataset and a benchmark from which additional studies can begin. The maps also define in detail the tectonic fabrics of the southwestern Colorado Plateaus Province. Overlaying the correlated lineaments on the normalized-density-of-vegetation-index image reveals that many of these lineaments correlate with the boundaries of vegetation zones in drainages and canyons and so may be controlling near-surface water availability in some places. Many derivative products can be produced from the database, such as fracture-density-estimate maps, and maps with the number of correlations color-coded to estimate the possible quality of correlation. The database contained in this report is designed to be used in a geographic information system and image-processing systems, and most data layers are in georeferenced tagged image format (Geotiff) or ARC grids. The report includes 163 map plates and various metadata, supporting, and statistical diagram files.

Data Series↗
USGS2002

Time-domain electromagnetic signatures of polymetallic vein deposits in Cottonwood Canyon area, Santa Cruz County, Arizona

This report tests the usefulness of airborne time-domain electromagnetic (TEM) data on three mineral-resource-related issues: (1) to test whether known mineral deposits at or near the surface display any signal in the TEM data; 2) determine whether TEM data can be used to locate bedrock concealed by basin fill; and (3) if the exposed mineral deposits display a signal in the TEM data, to determine if whether deposits are recognizable at depth in outcropping bedrock or in bedrock concealed beneath basin fill. Because Earth's total-intensity magnetic field data are also acquired with the TEM data, these data are included in the analysis. The Cottonwood Canyon area in Santa Cruz County, Arizona, contains several polymetallic vein deposits, including those of the Tyndall, Salero, and Wrightson mining districts, all of which have had significant mineral production. Polymetallic vein deposits, which generally consist of veins of disseminated metallic minerals, commonly exhibit a response to electrical geophysical methods. Also, on the basis of other studies, the conditions that produced the polymetallic vein mineralization in the region are believed to extend offshore into the bedrock concealed by basin fill. The polymetallic vein deposits of the Cottonwood Canyon area all display a geophysical signature in the TEM data. These deposits occur in bedrock that has, in general, a very low resistivity. The polymetallic vein deposits are associated with high-conductivity regions that extend from deep in the bedrock to the surface. These high-conductivity regions can be quite narrow (100 m) or quite wide (1 km); most are relatively narrow. Every known mineral deposit or prospect is associated with a high-conductivity feature. High-conductivity regions can also occur without an association with known mineral deposits. Airborne TEM data appear to be able to locate the basin fill/bedrock contact beneath basin fill. The basin fill (both dry and saturated) is generally more conductive than the bedrock. The low conductivity of the bedrock ensures that no signal from the bedrock is received from under the basin fill in most places. Therefore, in most areas of basin fill, the bedrock is interpreted to be the bottom of the signal in the conductivity-depth transforms (CDTs). Although the CDTs locate the basin-fill/bedrock contact, on the basis of a comparison with a recent report, they mostly overstate its depth by a factor of at least 2. Because CDTs based on airborne TEM data do not see into bedrock below basin fill, it is impossible to detect mineralization in the bedrock concealed by such fill. Although the geophysical signature of polymetallic vein deposits is seen at depth in outcropping bedrock, the existence of this geophysical signal does not guarantee the occurrence of polymetallic vein deposits.

Arizona↗
USGS2000

Operational guidelines (version 1.0) for geological fieldwork in areas endemic for Coccidioidomycosis (Valley Fever)

Coccidioidomycosis (Valley Fever) is a disease caused by the inhalation of the arthroconidia (spores) of Coccidioides immitis, a fungus that lives in the soils of southwestern United States. Although large numbers of people are exposed to the arthroconidia and are consequently infected, very few individuals contract the more serious forms of the disease. Earth scientists working in field areas where Coccidioides immitis is endemic have an increased risk of becoming infected. Because field operations often disturb the upper surface of the ground, they may inhale large numbers of arthroconidia. This also increases their risk of developing more severe forms of the disease. Any other occupations or activities that create dusty conditions in endemic areas also have increased risk of infection. Risk management strategies can lower the incidence of infection and also reduce the numbers of arthroconidia inhaled thereby decreasing the chances of developing more serious disease. Dust control, by utilizing dust masks, and dust prevention, by limiting ground disturbing activities, are the primary weapons against infection. However, infection risk can also be lowered by conducting fields studies in the winter months; avoiding sites favorable for Coccidioides immitis growth; seeking prompt medical treatment if flu-like or respiratory illness occur during, or within a few weeks following, fieldwork; getting a coccidioidin skin test to determine susceptibility to the disease; and by educating all members of the field party about the possibilities and consequences of infection.

Open-File Report↗
USGS1999

Geometry, structure, and concealed lithology of the San Rafael Basin, southeastern Arizona

The contiguous United States has been well explored for exposed conventional mineral deposits. Therefore, it is likely that many economically viable and strategically significant conventional undiscovered mineral deposits will be found in bedrock concealed beneath basin sediments. Mineral resource assessments must incorporate an understanding of the geometry, structure, and concealed lithology of basins in order to be accurate. This report presents an analysis of the basin geometry and structure of the San Rafael basin in southeastern Arizona. In addition, a new methodology for inferring concealed lithology is presented and applied in the San Rafael basin. Gravity data is used to model the geometry of the basin using recent models of sediment density vs. depth developed in the region. This modeling indicates that the basin has a maximum depth of approximately 1.05 km plus or minus 0.10 km. In the southern portion, the basin can be modeled as an asymmetric graben faulted on the western margin. The northern portion of the basin is structurally more complex and may have high angle faults on the western, northern, and eastern margin. Near-ground closely spaced Earth’s total intensity magnetic field data is used to locate concealed faults within the basin. This data is also used to infer lithology concealed by shallow basin sediments. Airborne Earth’s total intensity magnetic field data is used to help infer concealed lithology in deep portions of the basin. The product of integrating all data and interpretations is a map which presents the geometry of the basin, faults and contacts concealed by basin sediments, and an estimate of the bedrock lithology concealed by basin sediment. Based on basin geometry and concealed lithology, the San Rafael basin has a high potential for concealed mineral deposits on its western and northern margin. In particular, a newly discovered magnetic anomaly in the northern portion of the basin can be modeled as a granitic intrusion with highly altered margins and may represent a potential mineral resource target. Based on the permeability and porosity of upper basin fill found in nearby basins, the San Rafael basin may contain an aquifer up to 300 meters thick over a substantial area of the basin.

Arizona↗
USGS1999

An interpretation of the 1997 airborne electromagnetic (AEM) survey, Fort Huachuca vicinity, Cochise County, Arizona

In March of 1997, an airborne electromagnetic (AEM) survey of the Fort Huachuca Military Reservation and immediate surrounds was conducted. This survey was sponsored by the U.S. Army and contracted through the Geologic Division of the U.S. Geological Survey (USGS). Data were gathered by Geoterrex-Dighem Ltd. of Ottawa, Canada. The survey aircraft is surrounded by a coil through which a large current pulse is passed. This pulse induces currents in the Earth which are recorded by a set of three mutually perpendicular coils towed in a "bird" about 100 m behind and below the aircraft. The bird also records the Earth's magnetic field. The system samples the Earth response to the electromagnetic pulse about every 16 m along the aircraft flight path. For this survey, the bulk of the flightpaths were spaced about 400 m apart and oriented in a northeast-southwest direction extending from bedrock over the Huachuca Mountains to bedrock over the Tombstone Hills. A preliminary report on the unprocessed data collected in the field was delivered to the U.S. Army by USGS in July 1997 (USGS Open-File Report 97–457). The final data were delivered in March, 1998 by the contractor to USGS and thence to the U.S. Army. The present report represents the final interpretive report from USGS. The objectives of the survey were to: 1) define the structure of the San Pedro basin in the Sierra Vista-Fort Huachuca-Huachuca City area, including the depth and shape of the basin, and to delineate large faults that may be active within the basin fill and therefore important in the hydrologic regime; 2) define near surface and subsurface areas that contain a large volume fraction of silt and clay in the basin fill and which both reduce the volume of available storage for water and reduce the permeability of the aquifer; and 3) to evaluate the use of the time domain electromagnetic method in the southwest desert setting as a means of mapping depth to water.

Arizona↗
USGS1993

Quantifying favorableness for occurrence of a mineral deposit type using fuzzy logic; an example from Arizona

An application of possibility theory from fuzzy logic to the quantification of favorableness for quartz-carbonate vein deposits in the southern Santa Rita Mountains of southeastern Arizona is described. Three necessary but probably not sufficient conditions for the formation of these deposits were defined as the occurrence of carbonate berain rocks within hypabyssal depths, significant fracturing of the rocks, and proximity to a felsic intrusive. The quality of data available to evaluate these conditions is variable over the study area. The possibility of each condition was represented as a fuzzy set enumerated over the area. The intersection of the sets measures the degree of simultaneous occurrence of hte necessary factors and provides a measure of the possibility of deposit occurrence. Using fuzzy set technicques, the effect of one or more fuzzy sets relative to the others in the intersection can be controlled and logical combinations of the sets can be used to impose a time sequential constraint on the necessary conditions. Other necessary conditions, and supplementary conditions such as variable data quality or intensity of exploration can be included in the analysis by their proper representation as fuzzy sets.

Open-File Report↗