Search USGS⌕ Search

SEARCH · Search USGS

Results for “Geological & Geophysical Surveys”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
USGS1985

Management of ground water and evolving hydrogeologic studies in New Jersey : a heavily urbanized and industrialized state in the northeastern United States

New Jersey is the most densely populated and one of the most industrialized states in the United States. An abundance of freshwater and proximity to major northeastern metropolitan centers has facilitated this development. Pumpage of freshwater from all aquifers in the State in 1980 was 730 million gallons per day (2.76 million cubic meters per day). Management and efficient development of the ground-water resources of the State are the responsibility of the New Jersey Department of Environmental Protection. Laws have been enacted and updated by the State legislature to manage water allocation and to control the disposal of hazardous wastes. Present resource management is guided by the New Jersey Water-Supply Master Plan of 1981. Funding for management activities is partially derived from the sale of state-approved bonds. Effective planning and regional management require accurate and up-to-date hydrologic information and analyses. The U.S. Geological Survey, in cooperation with the New Jersey Geological Survey, is conducting three intensive ground-water studies involving the collection and interpretation of hydrologic data to meet the urgent water-management needs of New Jersey. These studies are part of a long-term cooperative program and are funded through the Water-Supply Bond Act of 1981. They began in 1983 and are scheduled to be completed in 1988. The project areas are situated in the New Jersey part of the Atlantic Coastal Plain in and near Atlantic City, Camden, and South River. They range in size from 400 to 1,200 mil (1,040 to 3,120 km2). The studies are designed to define the geology, hydrology, and geochemistry of the local ground-water systems. The results of these studies will enable the State to address more effectively major problems in these areas such as declining water levels, overpumping, saltwater intrusion, and ground-water contamination resulting from the improper disposal of hazardous wastes. Specific objectives of these studies by the U.S. Geological Survey are to (1) develop an accurate and up-to-date hydrogeologic data base, (2) design and implement a data-collection program and establish a computerized information management system, (3) refine the conceptualization of the ground-water flow system, and (4) define the geochemistry of the aquifer system by conducting a water-quality appraisal. The objectives are accomplished by standard hydrogeologic methods. Information concerning hydrogeologic framework, ground-water levels, water use, hydraulic characteristics, and water quality in the study areas is compiled from all available sources. Additional data needed are collected through well inventories, surface geophysical surveys, water-quality samplings, water-level measurements, and a well-drilling program. Interpretation of the flow system is based on the use of standard analytical techniques and digital flow modeling. Calibrated flow models will provide ground-water managers with a mechanism to develop and test regional water-supply strategies. Definition of the geochemistry of the aquifer system is accomplished through a variety of methods which depend on the problems and available data in the particular study area. The approach includes statistical analysis of water-quality data, reaction-path modeling, and determination of the movement of chemical constituents using analytical and numerical modeling techniques. A combined staff of 25 to 30 professionals and technicians from the New Jersey District office of the U.S. Geological Survey is committed to the three studies. The staff has specialists in geohydrology, numerical modeling, geochemistry, geophysics, and computer science. The findings of these studies will be published in data reports, interpretive reports, instructional manuals and journal articles.

New Jersey↗
USGS1978

Evaluation of Baltazor known geothermal resources area, Nevada

By virtue of the Geothermal Steam Act of 1970, the U.S. Geological Survey is required to appraise geothermal resources of the United States prior to competitive lease sales. This appraisal involves coordinated input from a variety of disciplines, starting with reconnaissance geology and geophysics. This paper describes how the results of several geophysical methods used in KGRA evaluation were interpreted by the authors, two geophysicists, involved with both the Evaluation Committee and the research program responsible for obtaining and interpreting the geophysical data to be used by the committee. ?? 1979.

Geothermics↗
USGS1978

Clarence Allen talks about the responsibilities in earthquake prediction

Dr. Clarence R. Allen is professor of geology and geophysics at the California Institute of Technology. He has been a member of advisory panels to the Executive Office of the President, National Academy of Sciences, National Science Foundation, U.S Geological Survey, UNESCO, California State Mining and Geology Board, and the California Department of Water Resources. Dr. Allen has been President of both the Geological Society of America and the Seismological Society of America (SSA). The title of this interview is based on his presidential address to the SSA in 1976.

Earthquake Information Bulletin (USGS)↗
USGS1988

Structure and stratigraphy of the western Florida shelf; Part I, Multichannel reflection seismic data

This paper presents a synthesis of multichannel seismic data on the Western Florida shelf (Fig. 1). This work is part of an ongoing regional program conducted by the U.S. Geological Survey in studying the Exclusive Economic Zones of the United States. The data include 1270 km of 32-fold, common-depth-point (CDP), reflection seismic line obtained with a 3200 m, 64 channel, hydrophone streamer and a 2000 in 3 airgun array. The rationale for the line layout was to tie eight key exploration wells among the 14 existing in federal waters prior to 1980 to 4 key wells in Florida. An attempt was also made to connect our survey with that of the University of Texas Institute of Geophysics in the deep Gulf of Mexico basin. A second set of 1500 km of 24-fold CDP data were collected using a 1200 m, 24-channel streamer and a 550 in 3 airgun source. This set was intended to tie additional wells, drilled between 1979 and 1983, and to infill our original net. Gravity and magnetic measurements were also made along these lines. Our subsurface information in federal waters consists of well logs and files released to us initially by the Conservation Division of the U.S. Geological Survey and subsequently by the U.S. Minerals Management Service. Most information from wells in state waters was provided by the Florida Geological Survey. Table 1 lists wells included in our study and summarizes the types of logs and other information available from each well. Spontaneous potential or gamma ray, resistivity or conductivity, sonic and density logs were generally available. Lithologic information, paleontologic and log picks on stratigraphic units and dip-meter data were also common. Check shot surveys for velocity analysis were available in three wells.

Florida↗
USGS1993

Application of borehole geophysics in defining the wellhead protection area for a fractured crystalline bedrock aquifer

Wellbore geophysical techniques were used to characterize fractures and flow in a bedrock aquifer at a site near Blackwater Brook in Dover, New Hampshire. The primary focus ofthis study was the development of a model to assist in evaluating the area surrounding a planned water supply well where contaminants introduced at the land surface might be induced to flow towards a pumping well. Well logs and geophysical surveys used in this study included lithologic logs based on examination of cuttings obtained during drilling; conventional caliper and natural gamma logs; video camera and acoustic televiewer surveys; highresolution vertical flow measurements under ambient conditions and during pumping; and borehole fluid conductivity logs obtained after the borehole fluid was replaced with deionized water. These surveys were used for several applications: 1) to define a conceptual model of aquifer structure to be used in groundwater exploration; 2) to estimate optimum locations for test and observation wells; and 3) to delineate a wellhead protection area (WHPA) for a planned water supply well. Integration of borehole data with surface geophysical and geological mapping data indicated that the study site lies along a northeast-trending intensely fractured contact zone between surface exposures of quartz monzonite and metasedimentary rocks. Four of five bedrock boreholes at the site were estimated to produce more than 150 gallons per minute (gpm) (568 L/min) of water during drilling. Aquifer testing and other investigations indicated that water flowed to the test well along fractures parallel to the northeast-trending contact zone and along other northeast and north-northwest-trending fractures. Statistical plots of fracture strikes showed frequency maxima in the same northeast and north-northwest directions, although additional maxima occurred in other directions. Flowmeter surveys and borehole fluid conductivity logging after fluid replacement were used to identify water-producing zones in the boreholes; fractures associated with inflow into boreholes showed a dominant northeast orientation. Borehole fluid conductivity logging after fluid replacement also gave profiles of such water-quality parameters as fluid electrical conductivity (FEC), pH, temperature, and oxidation-reduction potential, strengthening the interpretation of crossconnection of boreholes by certain fracture zones. The results of this study showed that the application of these borehole geophysical techniques at the Blackwater Brook site led to an improved understanding of such parameters as fracture location, attitude, flow direction and velocity, and water quality; all of which are important in the determination of a WHPA.

Log Analyst↗
USGS1994

Reconnaissance geologic mapping of a portion of the rain‐forest‐covered Guiana Shield, Northwestern Brazil, using SIR-B and digital aeromagnetic data

This paper documents the result of an integrated analysis of spaceborne radar (SIR-B) and digital aeromagnetic data carried out in the heavily forested Guiana Shield. The objective of the research is to interpret the geophysical data base to its limit to produce a reconnaissance geologic map as an aid to ground work planning in a worst‐case setting. Linear geomorphic features were identified based on the interpretation of the SIR-B image. Digital manipulation of aeromagnetic data allowed the development of a color‐shaded relief map of reduced‐to‐pole magnetic anomalies, a terrace‐magnetization map, and a map showing the location of maximum values of the horizontal component of the pseudogravity gradient (magnetization boundary lines). The resultant end product was a reconnaissance geologic map where broad terrane categories were delineated and geologic faults with both topographic and magnetic expression were defined. The availability of global spaceborne radar coverage in the 1990s and the large number of existing digital aeromagnetic surveys in northwestern Brazil indicate that this approach can be potentially useful for reconnaissance geologic mapping elsewhere in the Guiana Shield.

Geophysics↗
USGS1983

Geophysical investigations in the Dhahar-Al Hajrah region, Wadi Malahah Quadrangle, southwestern Saudi Arabia

Crone electromagnetic, self-potential, and induced polarization surveys were conducted in the Dhahar-Al Hajrah region, southwestern Saudi Arabia, in support of geological and geochemical exploration for volcanogenic sulfide deposits. Although a previous, airborne electromagnetic survey found no anomalies in the vicinity of the ancient mines in the region, surface indications of anomalous copper and zinc at both Dhahar and Al Hajrah are abundant. Reconnaissance Crone electromagnetic traverses across the Dhahar prospect area delineated numerous conductive zones, but none had a dip-angle anomaly of more than 10?. Similar results were obtained at Al Hajrah. With one or two encouraging exceptions, self-potential surveys at Al Hajrah showed only broad gradients and anomalies having amplitudes of less than 40 mV. Dipole-dipole induced polarization surveys at Al Hajrah delineated two nearly continuous polarizable zones having an aggregate strike length of almost 7 km. The two zones are symmetrically disposed on either side of a median aplitic dike and may lie on opposing limbs of a south-plunging antiform. Chargeabilities in the anomalous zones are weak to moderate but in most places are clearly associated with anomalous copper and (or) zinc concentrations found by surface sampling. Ground electromagnetic traverses are recommended to determine the most conductive intervals of anomalous induced polarization effect in the anomalous zones; these conductive intervals should then be tested by drilling, where appropriate. Reconnaissance self-potential traverses are also recommended at Dhahar, and additional ground electromagnetic surveys are recommended across two airborne electromagnetic anomalies located immediately southeast of the Al Hajrah target.

Open-File Report↗
USGS2012

Hydrostratigraphic interpretation of test-hole and surface geophysical data, Elkhorn and Loup River Basins, Nebraska, 2008 to 2011

The Elkhorn-Loup Model (ELM) was begun in 2006 to understand the effect of various groundwater-management scenarios on surface-water resources. During phase one of the ELM study, a lack of subsurface geological information was identified as a data gap. Test holes drilled to the base of the aquifer in the ELM study area are spaced as much as 25 miles apart, especially in areas of the western Sand Hills. Given the variable character of the hydrostratigraphic units that compose the High Plains aquifer system, substantial variation in aquifer thickness and characteristics can exist between test holes. To improve the hydrogeologic understanding of the ELM study area, the U.S. Geological Survey, in cooperation with the Nebraska Department of Natural Resources, multiple Natural Resources Districts participating in the ELM study, and the University of Nebraska-Lincoln Conservation and Survey Division, described the subsurface lithology at six test holes drilled in 2010 and concurrently collected borehole geophysical data to identify the base of the High Plains aquifer system. A total of 124 time-domain electromagnetic (TDEM) soundings of resistivity were collected at and between selected test-hole locations during 2008-11 as a quick, non-invasive means of identifying the base of the High Plains aquifer system. Test-hole drilling and geophysical logging indicated the base-of-aquifer elevation was less variable in the central ELM area than in previously reported results from the western part of the ELM study area, where deeper paleochannels were eroded into the Brule Formation. In total, more than 435 test holes were examined and compared with the modeled-TDEM soundings. Even where present, individual stratigraphic units could not always be identified in modeled-TDEM sounding results if sufficient resistivity contrast was not evident; however, in general, the base of aquifer [top of the aquifer confining unit (ACU)] is one of the best-resolved results from the TDEM-based models, and estimates of the base-of-aquifer elevation are in good accordance with those from existing test-hole data. Differences between ACU elevations based on modeled-TDEM and test-hole data ranged from 2 to 113 feet (0.6 to 34 meters). The modeled resistivity results reflect the eastward thinning of Miocene-age and older stratigraphic units, and generally allowed confident identification of the accompanying change in the stratigraphic unit forming the ACU. The differences in elevation of the top of the Ogallala, estimated on the basis of the modeled-TDEM resistivity, and the test-hole data ranged from 11 to 251 feet (3.4 to 77 meters), with two-thirds of model results being within 60 feet of the test-hole contact elevation. The modeled-TDEM soundings also provided information regarding the distribution of Plio-Pleistocene gravel deposits, which had an average thickness of 100 feet (30 meters) in the study area; however, in many cases the contact between the Plio-Pleistocene deposits and the overlying Quaternary deposits cannot be reliably distinguished using TDEM soundings alone because of insufficient thickness or resistivity contrast.

Nebraska↗
USGS1989

Summary geochemical maps of the Harrison 1° x 2° quadrangle, Arkansas and Missouri

This map is the first in a folio of maps of the Harrison 1° x 2° quadrangle, Arkansas and Missouri, prepared under the Conterminous United States Mineral Assessment Program. Additional maps showing various other geologic aspects of the Harrison quadrangle will be published as U.S. Geological Survey Miscellaneous Field Studies Maps bearing the same serial number with different letter suffixes (MF-1994-B, -C, and so on). Geochemical studies of the Harrison lo x 2° quadrangle, Arkansas and Missouri, are part of a joint multidisciplinary study by the U.S. Geological Survey; the Division of Geology and Land Survey, Missouri Department of Natural Resources; and the Arkansas Geological Commission. The objective of the joint study is to assess the mineral-resource potential of the area by integrated geologic, geochemical, and geophysical investigations.

Arkansas, Missouri↗
USGS1980

Chemical analyses of coal from the Mesa Verde Formation, Grand Mesa coal field, Delta and Mesa counties, Colorado

As part of a continuing program by the U.S. Geological Survey to collect and chemically analyze representative samples of U.S. coals, 45 coal samples were collected from the Upper Cretaceous Mesaverde Formation, Grand Mesa coal field, Delta and Mesa Counties, Colorado. These samples were collected from cores (30 samples, 11 locations), mines (11 face channel samples, 9 locations), and from drill cuttings (4 samples, 1 location). U.S. Geological Survey sample numbers, index map locations, coal thickness or depth interval sampled, and brief descriptions for the 45 samples are listed in table 1. Sampling locations are shown in figure 1. Geophysical logs for all samples summarized in this report can be found in Eager (1978,1979).

Colorado↗
USGS1981

Summary of radiometric anomalies in Alaska

The gamma ray anomalies and their related geological settings shown on this map are a compilation from the NURE reconnaissance surveys (LKB Resources Inc., 1978a, 1978b, 1978c, 1979; Texas Instruments, Inc., 1977, 1978, U.S. Research and Development, 1976; Western Geophysical Company of American, 1980.)

Alaska↗
USGS1982

GLORIA sidescan and seismic data collected by the DESV STARELLA along the continental slope and upper continental rise of the Eastern United States in 1979

A cruise on the- DESV STARELLA was conducted between October 23. 1979, and November 8, 1979, by the U.S. Geologic.al Survey (USGS) in cooperation with the United Kingdom's Institute of Oceanographic Sciences (IOS). The purpose of the study was to gain an overview of the morphology of large areas of the Continental Slope and upper Continental Rise off the eastern ·united States. Sidescan-sonar and single-channel seismic-reflection data were collected along the tracklines. The ship's position. was monitored using LORAN_C and satellite navigation techniques. The sidescan data were collected using the !OS-developed Geologic Long­-Range Inclined Asdic, Mark II (GLORIA II) system. GLORIA was operated at either a 20-second or 40-second sweep, giving maximum slant-range distances of 15 or 30 kilometers, respectively, to each side of the towed fish. The sidescan data were collected on graphic recorders and analog tapes. The tapes were played onto photographic paper in a facsimile machine; then these prints were photographically stretched to produce approximately isometric images .. The images were not corrected for slant-range distortion. Mosaics at a scale of 1:250,000 (Mercator projection) were made from the photographic images. The seismic· data consist of 40-in 3 airgun and 10-kHz echo-sounder profiles. The airgun data were recorded on EPC recorders at both 8- and 4- second sweep rates. The 10-kHz echo-sounder data were recorded on a wet-paper recorder at a 2-second sweep rate. Approximately 4,820 km of seismic and sonar-data wera collected from four areas of interest and along the lines connecting those areas. Area 1 includes the Continental Slope and upper Rise seaward of Georges Bank, between Northeast Channel and Alvin Canyon. Numerous lines were run here, resulting in approximately 2,500 km of seismic data and complete and overlapping GLORIA coverage of the area. A similar survey, consisting of approximately 1 2 200 km of trackline, was run in area 2, which includes the Continental Slope and upper Rise seaward of the middle Atlantic states between Hudson Canyon and Baltimore Canyon. A single line, 250 km long, was run through area 3 along the base of the Continental Slope from Cape Hatteras to latitude 33°N. off North and South Carolina. Two parallel lines, totaling 870 km, were run through area 4 along the Blake Escarpment, from the Blake Spur south to latitude 27°40'N. One line was run along the top of the escarpment and the other was run along the base of the escarpment. All the data can be studied at the U.S. Geological Survey offices in Woods Hole, MA 02543. Microfilm copies of the sidescan-monitor record as well as the airgun and 10-kHz profiles can be purchased only from the National Geophysical Data Center, NOAA, Code E64, 325 Broadway, Boulder, CO 80303 (303/497-6338). Photographic copies of the GLORIA mosaics can also be obtained only from this address.

Open-File Report↗
USGS2009

Physical property data from the ICDP-USGS Eyreville cores A and B, Chesapeake Bay impact structure, Virginia, USA, acquired using a multisensor core logger

The International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS) drilled three core holes to a composite depth of 1766 m within the moat of the Chesapeake Bay impact structure. Core recovery rates from the drilling were high (??90%), but problems with core hole collapse limited the geophysical downhole logging to natural-gamma and temperature logs. To supplement the downhole logs, ??5% of the Chesapeake Bay impact structure cores was processed through the USGS GeoTek multisensor core logger (MSCL) located in Menlo Park, California. The measured physical properties included core thickness (cm), density (g cm -3 ), P-wave velocity (m s -1 ), P-wave amplitude (%), magnetic susceptibility (cgs), and resistivity (ohm-m). Fractional porosity was a secondary calculated property. The MSCL data-sampling interval for all core sections was 1 cm longitudinally. Photos of each MSCL sampled core section were imbedded with the physical property data for direct comparison. These data have been used in seismic, geologic, thermal history, magnetic, and gravity models of the Chesapeake Bay impact structure. Each physical property curve has a unique signature when viewed over the full depth of the Chesapeake Bay impact structure core holes. Variations in the measured properties reflect differences in pre-impact target-rock lithologies and spatial variations in impact-related deformation during late-stage crater collapse and ocean resurge. ?? 2009 The Geological Society of America.

Special Paper of the Geological Society of America↗
USGS1961

An aeromagnetic profile from anchorage to Nome, Alaska

A total-intensity profile was obtained on a 500-mile flight by a U. S. Geological Survey airplane from Anchorage to Nome , Alaska , on May 4, 1954. The average flight altitude was 6,000 ft above sea level except over the Alaska Range where the flight altitude was 9,000 ft. This profile crossed eight of the major tectonic elements of Alaska at right angles to their trend and gives valuable regional information in an area where other geophysical and geological information is scarce or lacking. The profile has a net gradient downward to the northwest, most of which is ascribed to the component of the earth's main magnetic field along the flight traverse. The great variety of magnetic anomalies which are superimposed on this gradient originate from variations in lithology along the traverse. All the magnetic anomalies, except a large one over the Yukon River, are caused by magnetic rocks at or near the surface. The magnetic profile may be divided into four major segments and nine subsegments, each having a characteristic magnetic pattern. Most of these can be related to a tectonic unit. The large plutons of the Talkeetna geanticline are clearly defined by a group of anomalies having the highest amplitudes of any on the profile . The Matanuska geosyncline to the east is represented by a 25-mile section of sloping profile consistent with a thick sedimentary section but indicating that the geosyncline is comparatively narrow near Anchorage . The 200-mile central magnetic segment is relatively free from all but very minor anomalies. This segment includes the Alaska Range geosyncline, the Tanana geanticline, and the Kuskokwim geosyncline; showing only slight magnetic contrasts between each of these elements. The two geosynclines either have thick Mesozoic sedimentary sections or have underlying crystalline rocks which are low in magnetic susceptibility at shallow depths. The rocks of the geanticline have a low but not negligible magnetic susceptibility and are predominantly Paleozoic sedimentary rocks. A single 300-gamma anomaly on the west edge of the central segment is caused by a small, mafic intrusive body in the Paleozoic metamorphic rocks of Mt. Hurst. West of this anomaly the profile consists of a series of small sharp anomalies which are probably caused by Paleozoic metavolcanic rocks of the Ruby geanticline. The second largest anomaly on the profile is in the Koyukuk geosyncline over the Yukon River. The source is calculated to be more than a mile deep and may be an intrusive body at least 15 miles wide. This anomaly is flanked by 20-mile sections of flat or sloping profile which indicate areas of thick sedimentary rocks, particularly in the region west of the Yukon River. The 150-mile Norton Sound magnetic segment on the western end of the profile consists of many closely spaced anomalies produced by rocks which are either volcanic or similar to the Seward complex. Of the four Cenozoic basins or lowlands crossed by the profile , three are underlain by rocks of moderate to high magnetic susceptibility at shallow depths. These are the Cook Inlet basin, part of which overlaps rocks of the Talkeetna geanticline, the Innoko basin of central Alaska which overlies the rocks of the Ruby geanticline, and the Norton basin, in which sedimentary deposits are thin or absent. The fourth, the Minchumina basin, is underlain by the low-susceptibility rocks at the Tanana geanticline, which are also probably close to the surface.

Alaska↗