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At least 901 records · Page 50Linked to original sources
USGS2008

Preliminary Gravity and Ground Magnetic Data in the Arbuckle Uplift near Sulphur, Oklahoma

Improving knowledge of the geology and geophysics of the Arbuckle Uplift in south-central Oklahoma is a goal of the Framework Geology of Mid-Continent Carbonate Aquifers project sponsored by the United States Geological Survey (USGS) National Cooperative Geologic Mapping Program (NCGMP). In May 2007, we collected ground magnetic and gravity observations in the Hunton Anticline region of the Arbuckle Uplift, near Sulphur, Oklahoma. These observations complement prior gravity data collected for a project sponsored by the National Park Service and helicopter electromagnetic (HEM) and aeromagnetic data collected in March 2007 for the NCGMP project. This report describes the instrumentation and processing that was utilized in the May 2007 geophysical fieldwork, and it presents preliminary results as gravity anomaly maps and magnetic anomaly profiles. Digital tables of gravity and magnetic observations are provided as a supplement to this report. Future work will generate interpretive models of these anomalies and will involve joint analysis of these ground geophysical measurements with airborne and other geophysical and geological observations, with the goal of understanding the geological structures influencing the hydrologic properties of the Arbuckle-Simpson aquifer.

Open-File Report↗
USGS2015

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and other features in the aquifer system.

Alabama, Florida, Georgia, South Carolina↗
USGS1990

Magnetic and bathymetric data from R/V FARNELLA cruises FRNL87-1, 87-2, 87-3, 87-4 and 87-5 in the U.S. Atlantic Margin EEZ, southern Blake Escarpment, and Nova Scotia continental rise

During the winter and spring of 1987, the U.S. Geological Survey, in cooperation with the Institute of Oceanographic Sciences of the United Kingdom, collected approximately 31,350 line kilometers (km) of magnetic data and approximately 32,280 line km of bathymetric data in the U.S. Atlantic Margin Exclusive Economic Zone (EEZ), Southern Blake Escarpment, and Nova Scotia Rise (Fig. 1). Collected simultaneously with the magnetic and bathymetric data was a suite of geophysical data. These geophysical datasets will be released at a later date and include GLORIA (Geological LOng-Range Inclined Asdic) sidescan-sonar digital image data, 3.5 kilohertz (kHz) high-resolution sub-bottom profiler records, 10 kHz bottom profiler records from which bathymetric data were derived, and two channel seismic-reflection profiles. Survey line spacing was about 25 km in water depths exceeding 3,000 meters (m) and gradually decreased to less than 5 km in 200 m water depths. No areas were surveyed with depths shallower than 200 m. Orientation of the tracklines varies with respect to the trend of the bathymetric contours for each of the five legs (Fig.l).

Open-File Report↗
USGS1981

Geophysical log suite from drill hole No. 4, Mariano Lake-Lake Valley drilling project, McKinley County, New Mexico

In the fall of 1980, the U.S. Geological Survey contracted with .Longman Drilling Company of Albuquerque, New Mexico to rotary drill and core twelve holes along a north-south line from Mariano Lake to the vicinity of Lake Valley, New Mexico. This report incorporates the logs from drill hole no. 4. Similar reports on holes no. 1, 2, and 3 were released by the U.S. Geological Survey (1981a, b). The drilling project is funded under a reimbursable interagency agreement between the U.S. Bureau of Indian Affairs (BIA) and the U.S. Geological Survey (USGS). The program was designed by representatives of the BIA, USGS, and the Minerals Department of the Navajo Tribe.

New Mexico↗
USGS2009

Fossils, lithologies, and geophysical logs of the Mancos Shale from core hole USGS CL-1 in Montrose County, Colorado

As part of a multidisciplinary investigation of Mancos Shale landscapes in the Gunnison Gorge National Conservation Area in Delta and Montrose Counties of western Colorado by the U.S. Geological Survey, Bureau of Land Management, and Bureau of Reclamation, a core of the Upper Cretaceous Mancos Shale was obtained from a borehole, USGS CL-1, in NE1/4 sec. 8, T. 50 N., R. 9 W. (approximately lat 38.61717 degree(s) N., long 107.90174 degree(s) W.), near the town of Olathe. Geophysical records of the borehole include resistivity, gamma ray, and density logs. The core extends between depths of 20 and 557 ft and is about 2.5 in. in diameter. It is composed of calcareous silty shale, as well as scattered beds of limestone and bentonite which were deposited mainly in offshore marine environments during the Cenomanian, Turonian, and Coniacian Stages of the Cretaceous Series. The strata were sampled and analyzed to obtain geochemical data and to identify constituent fossils. Stratigraphic units within the Mancos in the core include the following members, in ascending order: Bridge Creek Limestone (part), Fairport, Blue Hill, Juana Lopez, Montezuma Valley, and Niobrara (part). Strata herein assigned to the Bridge Creek Limestone are about 18 ft thick and consist of silty shale that contains ammonites, bivalves, and a coral of Late Cenomanian age. Strata assigned to the Fairport are about 22 ft thick and composed mainly of calcarenite-bearing, calcareous shale. Fossils in this member include ammonites and bivalves of early middle Turonian age. Overlying the Fairport is the Blue Hill Member, which is about 139 ft thick, and consists of glauconitic, shaley siltstone, and less silty shale. The Juana Lopez Member, overlying the Blue Hill, is about 138 ft thick and composed mainly of calcarenitic, silty shale. Beds in this member contain ammonites and bivalves of late middle and early late Turonian ages. Overlying the Juana Lopez is the Montezuma Valley Member, which is about 55 ft thick and consists of calcarenitic, calcareous silty shale. The Montezuma Valley Member contains ammonites and bivalves of late Turonian age. It is overlain by a lower part of the Niobrara Member of the Mancos Shale which is laterally equivalent to the Fort Hays Limestone Member and part of the overlying Smoky Hill Member of the Niobrara Formation at outcrops in central Colorado. Strata in the core comparable to the Fort Hays are about 39 ft thick and include shaley limestone and calcareous shale, which contain lower Coniacian bivalves. Strata in the core equivalent to part of the Smoky Hill are about 126 ft thick and consist mainly of calcareous silty shale which also contains lower Coniacian bivalves.

Open-File Report↗
USGS1993

Summary of the mineral- and energy-resource endowment, BLM roswell resource area, east-central New Mexico

In this summary of two comprehensive resource reports produced by the U.S. Bureau of Mines and the U.S. Geological Survey for the U.S. Bureau of Land Management, we discuss the mineral- and energyresource endowment of the 14-millon-acre Roswell Resource Area, New Mexico, managed by the Bureau of Land Management. The Bureau and Survey reports result from separate studies that are compilations of published and unpublished data and integrate new findings on the geology, geochemistry, geophysics, mineral, industrial, and energy commodities, and resources for the seven-county area. The reports have been used by the Bureau of Land Management in preparation of the Roswell Resource Area Resource Management Plan, and will have future use in nationwide mineral- and energy-resource inventories and assessments, as reference and training documents, and as public-information tools. In the Roswell Resource Area, many metals, industrial mineral commodities, and energy resources are being, or have been, produced or prospected. These include metals and high-technology materials, such as copper, gold, silver, thorium, uranium and/or vanadium, rare-earth element minerals, iron, manganese, tungsten, lead, zinc, and molybdenum; industrial mineral resources, including barite, limestone/dolomite, caliche, clay, fluorspar, gypsum, scoria, aggregate, and sand and gravel; and fuels and associated resources, such as oil, gas, tar sand and heavy oil, coal, and gases associated with hydrocarbons. Other commodities that have yet to be identified in economic concentrations include potash, halite, polyhalite, anhydrite, sulfur, feldspar, building stone and decorative rock, brines, various gases associated with oil and gas exploration, and carbon dioxide. ?? 1993 Oxford University Press.

Nonrenewable Resources↗
USGS2016

Developing integrated methods to address complex resource and environmental issues

Introduction This circular provides an overview of selected activities that were conducted within the U.S. Geological Survey (USGS) Integrated Methods Development Project, an interdisciplinary project designed to develop new tools and conduct innovative research requiring integration of geologic, geophysical, geochemical, and remote-sensing expertise. The project was supported by the USGS Mineral Resources Program, and its products and acquired capabilities have broad applications to missions throughout the USGS and beyond. In addressing challenges associated with understanding the location, quantity, and quality of mineral resources, and in investigating the potential environmental consequences of resource development, a number of field and laboratory capabilities and interpretative methodologies evolved from the project that have applications to traditional resource studies as well as to studies related to ecosystem health, human health, disaster and hazard assessment, and planetary science. New or improved tools and research findings developed within the project have been applied to other projects and activities. Specifically, geophysical equipment and techniques have been applied to a variety of traditional and nontraditional mineral- and energy-resource studies, military applications, environmental investigations, and applied research activities that involve climate change, mapping techniques, and monitoring capabilities. Diverse applied geochemistry activities provide a process-level understanding of the mobility, chemical speciation, and bioavailability of elements, particularly metals and metalloids, in a variety of environmental settings. Imaging spectroscopy capabilities maintained and developed within the project have been applied to traditional resource studies as well as to studies related to ecosystem health, human health, disaster assessment, and planetary science. Brief descriptions of capabilities and laboratory facilities and summaries of some applications of project products and research findings are included in this circular. The work helped support the USGS mission to “provide reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.” Activities within the project include the following: Spanned scales from microscopic to planetary; Demonstrated broad applications across disciplines; Included life-cycle studies of mineral resources; Incorporated specialized areas of expertise in applied geochemistry including mineralogy, hydrogeology, analytical chemistry, aqueous geochemistry, biogeochemistry, microbiology, aquatic toxicology, and public health; and Incorporated specialized areas of expertise in geophysics including magnetics, gravity, radiometrics, electromagnetics, seismic, ground-penetrating radar, borehole radar, and imaging spectroscopy. This circular consists of eight sections that contain summaries of various activities under the project. The eight sections are listed below: Laboratory Facilities and Capabilities, which includes brief descriptions of the various types of laboratories and capabilities used for the project; Method and Software Development, which includes summaries of remote-sensing, geophysical, and mineralogical methods developed or enhanced by the project; Instrument Development, which includes descriptions of geophysical instruments developed under the project; Minerals, Energy, and Climate, which includes summaries of research that applies to mineral or energy resources, environmental processes and monitoring, and carbon sequestration by earth materials; Element Cycling, Toxicity, and Health, which includes summaries of several process-oriented geochemical and biogeochemical studies and health-related research activities; Hydrogeology and Water Quality, which includes descriptions of innovative geophysical, remote-sensing, and geochemical research pertaining to hydrogeology and water-quality applications; Hazards and Disaster Assessment, which includes summaries of research and method development that were applied to natural hazards, human-caused hazards, and disaster assessments; and Databases and Framework Studies, which includes descriptions of fundamental applications of geophysical studies and of the importance of archived data.

Circular↗
USGS2012

Construction diagrams, geophysical logs, and lithologic descriptions for boreholes USGS 103, 105, 108, 131, 135, NRF-15, and NRF-16, Idaho National Laboratory, Idaho

This report, prepared in cooperation with the U.S. Department of Energy, summarizes construction, geophysical, and lithologic data collected from about 4,509 feet of core from seven boreholes deepened or drilled by the U.S. Geological Survey (USGS), Idaho National Laboratory (INL) Project Office, from 2006 to 2009 at the INL. USGS 103, 105, 108, and 131 were deepened and cored from 759 to 1,307 feet, 800 to 1,409 feet, 760 to 1,218 feet, and 808 to 1,239 feet, respectively. Boreholes USGS 135, NRF-15, and NRF-16 were drilled and continuously cored from land surface to 1,198, 759, and 425 feet, respectively. Cores were photographed and digitally logged by using commercially available software. Borehole descriptions summarize location, completion date, and amount and type of core recovered.

Idaho↗
USGS1988

Heavy-Mineral Placer Potential Map of the U.S. Continental Shelf, Western and Northern Gulf of Mexico

The establishment of the Exclusive Economic Zone (EEZ) in 1983 by Presidential Proclamation opened for natural resource exploration a vast offshore frontier area contiguous to the United States and its territories. The EEZ extends from the seaward limit of state waters (3 nautical mi from shore) to 200 nautical mi offshore, and it includes the continental shelves. Within the context of the EEZ natural resource assessment effort, the purpose of this study is to delineate, on a regional basis, the potential for heavy-mineral placers on the U.S. Continental Shelf in the western and northern Gulf of Mexico from the United States-Mexico border to the Alabama-Florida state line. This map is intended to serve as a general guide for placer exploration. It shows favorable sea-floor areas for placer occurrence in water depths ranging from 0 to 100 fathoms (600 ft). The map can be used as a guide for focusing costly exploratory efforts, such as coring operations and geophysical surveys. The potential economic value of heavy-mineral placer concentrations on the U.S. Continental Shelf is a function of both geologic and economic variables. Geologic variables include the composition and concentration of the heavy-mineral assemblages and their environment of deposition. Economic variables include the current world market price of extracted metals, as well as the cost of mining, processing, and marketing the metals. These economic factors, in turn, are tempered by the nation1s socio-political climate, which determines its need for specific mineral resources at any given time.

Miscellaneous Field Studies Map↗
USGS1980

High-resolution seismic-reflection profiles collected by the R/V James M. Gilliss, cruise GS 7903-4, in the Baltimore Canyon outer continental shelf area, offshore New Jersey

High-resolution seismic-reflection profiles were collected by the U.S. Geological Survey (USGS) aboard R/V JAMES M. GILLIS (cruise GS 7903-4) from 27 June to 11 July 1979 over the Continental Slope of the Eastern United States between Lindenkohl and Hudson Canyons. These data were acquired as part of a study to determine potential geologic hazards to petroleum development of the Baltimore Canyon trough area. On this cruise, the Continental Slope between Carteret and South Toms Canyons was surveyed along lines spaced one-half nautical mile apart to study the size and distribution of mass-wasting features as a guide to assess the importance of mass-wasting processes on the Continental Slope. The seimsic-reflection profiles were placed to complement other data gathered previously by the USGS and to continue a survey grid begun in 1978 aboard the R/V COLUMBUS !SELIN, cruise CI 7807-1. Track-line distances totaled 1,555 km of 40-in3 air-gun (with wave shaper) profiles, 1, 750 km of 800-J sparker data, and 1,780 km of 3 .5-kHz data. All data are of high quality. A side-scan sonar system was operated briefly along the uppermost Continental Slope to acquire data over 70 km of ship's track. In addition, experimental profiling data were collected from a hydrophone towed at depth over the midslope on the end of the side-scan cable; the surface-towed sparker was used as a sound source. High-resolution profiles were collected by this method over 105 km of track. Navigation was by Loran-C (5-minute fix interval) and satellite. The original data may be inspected at the offices of the U.S. Geological Survey in Woods Hole, Massachusetts 02543. Microfilm copies of the data from this cruise are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, Colorado 80303.

Open-File Report↗
USGS2000

Hydrogeologic and geochemical characteristics of the Ogallala and White River aquifers, Cheyenne, Wyoming

The Ogallala aquifer and the underlying White River aquifer are important ground-water resources of public and private drinking water in the Cheyenne, Wyoming area. In 1997, as part of a cooperative project between the Cheyenne Board of Public Utilities and the U.S. Geological Survey, a well was installed to develop information for those two aquifers. Information provided for the Ogallala aquifer included core descriptions, geophysical logs, water levels, aquifer transmissivity, water quality, isotopic analysis, and geochemical modeling. Information for the White River aquifer was limited to core descriptions and geophysical logs.Evaluation of the core obtained from the drill hole showed the sediments to be primarily sands, silts, and clays. The thickness of the Ogallala Formation at the well site was estimated to be 246 feet. Water levels and precipitation from October 1, 1998 to September 30, 1999 indicated that water levels responded to precipitation. During that time, water levels ranged from 6,002.41 feet to 6,004.27 feet above mean sea level. The transmissivity was estimated to be 1.1 feet squared/day. The temperature differences between the municipal water and the Ogallala aquifer water were examined in relation to selected hydraulic conductivities and it was found that the warmer municipal water would slightly increase the hydraulic conductivity if the water were injected into the Ogallala aquifer.The water quality of a sample from the Ogallala 1 well indicated the predominant major ions were calcium, magnesium, and bicarbonate. Isotopic analyses of hydrogen-2, tritium, chlorine-36, carbon-14, and carbon-13 indicated the water was a mixture of pre- and post-1953 recharge. A simple geochemical mixing model indicated there was the potential for dissolution of anhydrite, calcite, gypsum, and dolomite and precipitation of goethite, hematite, pyrolusite, and amorphous ferric hydroxide if municipal and Ogallala aquifer waters were mixed.

Water-Resources Investigations Report↗
USGS2013

Correlation of geothermal springs with sub-surface fault terminations revealed by high-resolution, UAV-acquired magnetic data

There is widespread agreement that geothermal springs in extensional geothermal systems are concentrated at fault tips and in fault interaction zones where porosity and permeability are dynamically maintained (Curewitz and Karson, 1997; Faulds et al., 2010). Making these spatial correlations typically involves geological and geophysical studies in order to map structures and their relationship to springs at the surface. Geophysical studies include gravity and magnetic surveys, which are useful for identifying buried, intra-basin structures, especially in areas where highly magnetic, dense mafic volcanic rocks are interbedded with, and faulted against less magnetic, less dense sedimentary rock. High-resolution magnetic data can also be collected from the air in order to provide continuous coverage. Unmanned aerial systems (UAS) are well-suited for conducting these surveys as they can provide uniform, low-altitude, high-resolution coverage of an area without endangering crew. In addition, they are more easily adaptable to changes in flight plans as data are collected, and improve efficiency. We have developed and tested a new system to collect magnetic data using small-platform UAS. We deployed this new system in Surprise Valley, CA, in September, 2012, on NASA's SIERRA UAS to perform a reconnaissance survey of the entire valley as well as detailed surveys in key transition zones. This survey has enabled us to trace magnetic anomalies seen in ground-based profiles along their length. Most prominent of these is an intra-basin magnetic high that we interpret as a buried, faulted mafic dike that runs a significant length of the valley. Though this feature lacks surface expression, it appears to control the location of geothermal springs. All of the major hot springs on the east side of the valley lie along the edge of the high, and more specifically, at structural transitions where the high undergoes steps, bends, or breaks. The close relationship between the springs and structure terminations revealed by this study is unprecedented. Collecting magnetic data via UAS represents a new capability in geothermal exploration of remote and dangerous areas that significantly enhances our ability to map the subsurface.

California↗
USGS2018

Airborne electromagnetic imaging of permafrost for hydrologic and infrastructure studies

Permafrost is found throughout northern latitudes, and has far reaching implications for natural and man - made environments including hydrologic processes, landscape dynamics, ecosystems, and infrastructure. While maps of near - surface permafrost characteristics are available, relatively little is known about permafrost distributions at depth over large areas. Her e, we summarize several frequency domain airborne electromagnetic (AEM) surveys acquired within interior Alaska from 2006 – 2016 that were collected to improve understand ing of permafrost and geological controls on hydrologic processes and infrastructure. Results of the AEM surveys are supported by both hydrogeophysical numerical models and ground - based geophysical observations.

Alaska↗
USGS1982

Earth Science Information System (ESIS)

The Earth Science Information System (ESIS) was developed in 1981 by the U.S. Geological Survey's Office of the Data Administrator. ESIS serves as a comprehensive data management facility designed to support the coordination, integration, and standardization of scientific, technical, and bibliographic data of the U.S. Geological Survey (USGS). ESIS provides, through an online interactive computer system, referral to information about USGS data bases, data elements which are fields in the records of data bases, and systems. The data bases contain information about many subjects from several scientific disciplines such as: geology, geophysics, geochemistry, hydrology, cartography, oceanography, geography, minerals exploration and conservation, and satellite data sensing.

Report↗
USGS2015

Archive of sediment data from vibracores collected in 2010 offshore of the Mississippi barrier islands

In 2010, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center collected sediment cores from coastal waters offshore of the Mississippi barrier islands. With funding support from the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility project, 65 subaqueous sediment cores were collected over an area of 480 square kilometers (km 2 ), from Ship Island to Petit Bois Island Pass, Mississippi, within the boundary of Gulf Islands National Seashore. This represents only a fraction of the total area encompassed by the NGOM project, which extends from Sabine Lake, Louisiana, to Perdido Bay, Alabama. The primary objectives of the NGOM project are to understand the evolution of coastal ecosystems on the northern gulf coast, the impact of human activities on these ecosystems, and the vulnerability of ecosystems and human communities to more frequent and intense hurricanes in the future. Selection of the core site locations was based on geophysical surveys conducted around the islands from 2008 to 2010. The surveys, using acoustic systems to image and interpret the nearsurface stratigraphy, were conducted to investigate the geologic controls on island evolution. This data series serves as an archive of sediment data collected from August to September 2010, offshore of the Mississippi barrier islands. Data products, including descriptive core logs, core photographs, results of sediment grain-size analyses, sample location maps, and geographic information system (GIS) data files with accompanying formal Federal Geographic Data Committee (FDGC) metadata can be downloaded from the data products and downloads page.

Mississippi↗
USGS2019

The USGS National crustal model for seismic hazard studies: 2019 update

The United States Geological Survey (USGS) National Crustal Model (NCM) is being developed to assist in the modeling of seismic hazards across the conterminous United States, specifically by improving estimates of site response. The NCM is composed of geophysical profiles, extending from the Earth’s surface into the upper mantle, constructed from 5 primary elements: 1) depth to bedrock and basement; 2) 3D geologic framework; 3) petrologic and mineral physics database; 4) 3D temperature model; and 5) calibration of a porosity and attenuation model. Parameters needed to estimate site response for existing ground motion models (GMMs), including the time-averaged velocity in the upper 30 meters (VS30) and the depths to 1.0 and 2.5 km/s shear-wave velocity (Z1.0 and Z2.5), can be extracted from the NCM. As GMMs develop, other metrics could also be extracted or derived from the NCM such as fundamental frequency, a fully frequency-dependent site response function, or 3D geophysical volumes for wavefield simulations. Application of the NCM may also benefit other aspects of seismic hazard analysis including better accounting for path-dependent attenuation and geometric spreading and more accurate estimation of earthquake source properties such as hypocentral location and stress drop.

Conference Paper↗
USGS2012

Quantification of aquifer properties with surface nuclear magnetic resonance in the Platte River valley, central Nebraska, using a novel inversion method

Surface nuclear magnetic resonance, a noninvasive geophysical method, measures a signal directly related to the amount of water in the subsurface. This allows for low-cost quantitative estimates of hydraulic parameters. In practice, however, additional factors influence the signal, complicating interpretation. The U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District, evaluated whether hydraulic parameters derived from surface nuclear magnetic resonance data could provide valuable input into groundwater models used for evaluating water-management practices. Two calibration sites in Dawson County, Nebraska, were chosen based on previous detailed hydrogeologic and geophysical investigations. At both sites, surface nuclear magnetic resonance data were collected, and derived parameters were compared with results from four constant-discharge aquifer tests previously conducted at those same sites. Additionally, borehole electromagnetic-induction flowmeter data were analyzed as a less-expensive surrogate for traditional aquifer tests. Building on recent work, a novel surface nuclear magnetic resonance modeling and inversion method was developed that incorporates electrical conductivity and effects due to magnetic-field inhomogeneities, both of which can have a substantial impact on the data. After comparing surface nuclear magnetic resonance inversions at the two calibration sites, the nuclear magnetic-resonance-derived parameters were compared with previously performed aquifer tests in the Central Platte Natural Resources District. This comparison served as a blind test for the developed method. The nuclear magnetic-resonance-derived aquifer parameters were in agreement with results of aquifer tests where the environmental noise allowed data collection and the aquifer test zones overlapped with the surface nuclear magnetic resonance testing. In some cases, the previously performed aquifer tests were not designed fully to characterize the aquifer, and the surface nuclear magnetic resonance was able to provide missing data. In favorable locations, surface nuclear magnetic resonance is able to provide valuable noninvasive information about aquifer parameters and should be a useful tool for groundwater managers in Nebraska.

Nebraska↗
USGS1978

Porphyry copper exploration model for northern Sonora, Mexico

The regional tectonic pattern of the porphyry copper province of northern Sonora, Mexico, is similar to, but more complex than, the Colorado mineral belt. Four northeast-trending shear zones, spaced at 30- to 50-kilometer intervals from Hermosillo, Mexico, north to Nogales, Mexico, are interpreted from analysis of lineament data from Landsat-1 images. From comparison with other areas, these zones are believed to have Precambrian ancestry. North-northwest-trending lineaments, which commonly occur along range fronts, are interpreted to be the principal basin and range faults. North-south- and west-northwest-trending lineaments are believed to be related to lesser faults and fractures. Areas of hydrothermal alteration have been mapped on a regional scale by use of digital image-processing techniques. These altered areas occur on the flanks of the northeast-trending shear zones, generally near intersections with north-northwest-trending lineaments. This tectonic framework with associated alteration is similar to patterns in the Colorado Plateau, the porphyry copper province of Arizona, and central Mexico and is supported by relationships found in limited local mapping. The pattern of northeast-trending shear zones and north-northwest-trending faults in northern Sonora closely resembles the tectonic framework of the Colorado mineral belt. The younger sedimentary and volcanic cover, however, has not been eroded in Sonora as it has been in the Colorado mineral belt. This comparison with the Colorado mineral belt suggests that mineral deposits are most likely to be found in altered areas where a northeast-trending shear zone is intersected by north-northwest-trending faults. Seven areas with these characteristics have been defined in Sonora and are being evaluated by means of regional geophysical and geochemical data.

Sonora↗