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At least 487 records · Page 27Linked to original sources
USGS2010

Helicopter electromagnetic and magnetic geophysical survey data, portions of the North Platte and South Platte Natural Resources Districts, western Nebraska, May 2009

This report is a release of digital data from a helicopter electromagnetic and magnetic survey that was conducted during June 2009 in areas of western Nebraska as part of a joint hydrologic study by the North Platte Natural Resource District (NRD), South Platte NRD, and U.S. Geological Survey (USGS). Flight lines for the survey totaled 937 line kilometers (582 line miles). The objective of the contracted survey, conducted by Fugro Airborne, Ltd., is to improve the understanding of the relation between surface-water and groundwater systems critical to developing groundwater models used in management programs for water resources. A unique aspect of the survey is the flight line layout. One set of flight lines was flown in a zig-zag pattern extending along the length of the previously collected airborne data. The success of this survey design depended on a well-understood regional hydrogeologic framework and model developed by the Cooperative Hydrologic Study of the Platte River Basin and the airborne geophysical data collected in 2008. Resistivity variations along lines could be related to this framework. In addition to these lines, more traditional surveys consisting of parallel flight lines, separated by about 400 meters were carried out for three blocks in the North Platte NRD, the South Platte NRD and in the area of Crescent Lakes. These surveys helped to establish the spatial variations of the resistivity of hydrostratigraphic units. An additional survey was flown over the Crescent Lake area. The objective of this survey, funded by the USGS Office of Groundwater, was to map shallow hydrogeologic features of the southwestern part of the Sand Hills that contain a mix of fresh to saline lakes.

Open-File Report↗
USGS2011

Helicopter electromagnetic and magnetic geophysical survey data, Swedeburg and Sprague study areas, eastern Nebraska, May 2009

This report is a release of digital data from a helicopter electromagnetic and magnetic survey conducted by Fugro Airborne Surveys in areas of eastern Nebraska as part of a joint hydrologic study by the Lower Platte North and Lower Platte South Natural Resources Districts, and the U.S. Geological Survey. The survey flight lines covered 1,418.6 line km (882 line mile). The survey was flown from April 22 to May 2, 2009. The objective of the contracted survey was to improve the understanding of the relation between surface water and groundwater systems critical to developing groundwater models used in management programs for water resources. The electromagnetic equipment consisted of six different coil-pair orientations that measured resistivity at separate frequencies from about 400 hertz to about 140,000 hertz. The electromagnetic data were converted to georeferenced electrical resistivity grids and maps for each frequency that represent different approximate depths of investigation for each survey area. The electrical resistivity data were input into a numerical inversion to estimate resistivity variations with depth. In addition to the electromagnetic data, total field magnetic data and digital elevation data were collected. Data released in this report consist of flight line data, digital grids, digital databases of the inverted electrical resistivity with depth, and digital maps of the apparent resistivity and total magnetic field. The range of subsurface investigation is comparable to the depth of shallow aquifers. The survey areas, Swedeburg and Sprague, were chosen based on results from test flights in 2007 in eastern Nebraska and needs of local water managers. The geophysical and hydrologic information from U.S. Geological Survey studies are being used by resource managers to develop groundwater resource plans for the area.

Open-File Report↗
USGS2011

Geophysical and flow-weighted natural-contaminant characterization of three water-supply wells in New Hampshire

Three bedrock water-supply systems in New Hampshire were studied, using borehole geophysics and flow-weighted sampling techniques, to determine the sources and distribution of natural contaminants in water entering the boreholes and to assess whether borehole modifications might be used to reduce contaminant levels. Well water in more than 100 community water-supply systems in New Hampshire have natural contaminants, such as arsenic and uranium, above the U.S. Environmental Protection Agency maximum contaminant levels of 10 and 30 micrograms per liter, respectively. The water-system wells were studied to identify fractional contributions of natural contaminants from specific fracture zones. The yields and flow-weighted contaminant levels of such fracture zones were assessed to determine if a modification of the borehole might lead to a reduction in the system’s contaminant levels. The water-supply systems investigated were typical of small community water systems in New Hampshire where a water system may serve 100 connections or less. Each water system consisted of two wells, approximately 300 to 400 feet deep, in generally low-yielding (about 10 gallons per minute or less) crystalline bedrock. The wells were typically operated a few hours per day to fill a storage tank and had tens of feet of drawdown caused by the low well yields. The systems selected had contaminant concentrations slightly above MCL, or a low-level contamination. One of the water systems investigated had low-level (10 to 24 micrograms per liter) arsenic contamination, and two of the water systems had low-level uranium (30 to 40 micrograms per liter) contamination. The contaminant values were blended-water concentrations from the two wells in a system. Each water system had differences in contaminant concentrations between the two wells. In each case, the well with the greater concentration of the two was selected for investigation. In two of the three systems investigated, there was either not enough variation in the borehole contaminant concentration or not enough water-yielding fractures for borehole modifications to be a viable potential remedy to elevated contamination. However, borehole and contaminant conditions in one of the bedrock supply-well systems may be favorable to potential improvement of supplied water by borehole modification where selected fracture zones are sealed off from supplying water to the well.

New Hampshire↗
USGS2011

Identification of mineral resources in Afghanistan—Detecting and mapping resource anomalies in prioritized areas using geophysical and remote sensing (ASTER and HyMap) data

As part of the U.S. Geological Survey (USGS) and Department of Defense Task Force for Business and Stability Operations (TFBSO) natural resources revitalization activities in Afghanistan (Peters and others, 2011), three new datasets have been collected, compiled, and analyzed. These data have been used to more fully evaluate the areas of interest (AOIs; fig. 1 ) where, on the basis of previous U.S.S.R. and Afghanistan studies, the opportunity for early economic development of a number of different mineral, commodity, and deposit types had been identified (Peters and others, 2007; Peters and others, 2011). The new data compilations include (1) regional magnetic and gravity data for use in the characterization of subsurface composition and structure (Sweeney and others, 2006a,b; Ashan and others, 2007; Sweeney and others, 2007; Ashan and others, 2008; Shenwary and others, 2011), (2) Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data to identify and evaluate surficial alteration patterns related to industrial minerals and other selected targets, and (3) HyMap imaging spectrometer data for characterization and mapping of surficial mineralogy (Cocks and others, 1998; Kokaly and others, 2008; Peters and others, 2011). These datasets have served as fundamental building blocks for the resource evaluation by Peters and others (2011). During the independent analysis of the geophysical, ASTER, and imaging spectrometer (HyMap) data by USGS scientists, previously unrecognized targets of potential mineralization were identified using evaluation criteria most suitable to the individual dataset. These anomalous zones offer targets of opportunity that warrant additional field verification. This report describes the standards used to define the anomalies, summarizes the results of the evaluations for each type of data, and discusses the importance and implications of regions of anomaly overlap between two or three of the datasets.

Open-File Report↗
USGS2011

Borehole geophysical and flowmeter data for eight boreholes in the vicinity of Jim Woodruff Lock and Dam, Lake Seminole, Jackson County, Florida

Borehole geophysical logs and flowmeter data were collected in April 2011 from eight boreholes to identify the depth and orientation of cavernous zones within the Miocene Tampa Limestone in the vicinity of Jim Woodruff Lock and Dam in Jackson County, Florida. These data are used to assess leakage near the dam. Each of the eight boreholes was terminated in limestone at depths ranging from 84 to 104 feet. Large cavernous zones were encountered in most of the borings, with several exceeding 20-inches in diameter. The cavernous zones generally were between 1 and 5 feet in height, but a cavern in one of the borings reached a height of about 6 feet. The resistivity of limestone layers penetrated by the boreholes generally was less than 1,000 ohm-meters. Formation resistivity near the cavernous zones did not show an appreciable contrast from surrounding bedrock, probably because the bedrock is saturated, owing to its primary permeability. Measured flow rates in the eight boreholes determined using an electromagnetic flowmeter were all less than ±0.1 liter per second. These low flow rates suggest that vertical hydraulic gradients in the boreholes are negligible and that hydraulic head in the various cavernous zones shows only minor, if any, variation.

Open-File Report↗
USGS2011

Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

Open-File Report↗
USGS2011

Geophysical, stratigraphic, and flow-zone logs of selected wells in Cayuga County, New York, 2001–2011

Geophysical logs were collected and analyzed along with bedrock core samples and bedrock outcrops to define the bedrock stratigraphy and flow zones penetrated by 93 monitor and water-supply wells in Cayuga County, New York. The work was completed from 2001 through 2011 as part of an investigation of volatile-organic compound contamination in the carbonate-bedrock aquifer system between Auburn and Union Springs. The borehole logs included gamma, caliper, wellbore image, fluid property, and flow logs. The log information was used with bedrock core samples to define the regional stratigraphy, evaluate flow zones within the bedrock aquifers, and develop and implement a multilevel monitoring design for groundwater levels and water quality within the study area.

New York↗
USGS2013

High-Resolution geophysical data from the inner continental shelf at Vineyard Sound, Massachusetts

The U.S. Geological Survey (USGS) and the Massachusetts Office of Coastal Zone Management (CZM) have mapped approximately 340 square kilometers of the inner continental shelf in Vineyard Sound, Massachusetts, under a cooperative mapping program. The geophysical data collected between 2009 and 2011 by the U.S. Geological Survey as part of this program are published in this report. The data include (1) swath bathymetry from interferometric sonar, (2) acoustic backscatter from sidescan sonar, and (3) seismic-reflection profiles from a chirp subbottom profiler. These data were collected to support research on the influence of sea-level change and sediment supply on coastal evolution and sediment transport processes and to provide baseline seabed characterization information required for management of coastal and offshore resources within the coastal zone of Massachusetts.

Massachusetts↗
USGS2012

Shipboard surveys track magnetic sources in marine sediments--geophysical studies of the Stono and North Edisto Inlets near Charleston, South Carolina

Magnetic field data are traditionally used to analyze igneous and metamorphic rocks, but recent efforts have shown that magnetic sources within sediments may be detectable, suggesting new applications for high-resolution magnetic field surveys. Candidates for sedimentary sources include heavy mineral sand concentrations rich in magnetite or hematite, alteration-induced glauconite, or biogenic magnetite. Magnetic field surveys can be used to map the distributions of such sources with much denser and more widespread coverage than possible by sampling. These data can then provide constraints on the composition history of local sediments. Mapping such sediments requires the sensor to be relatively close to the source, and filtering approaches may be needed to distinguish signals from both system noise and deeper basement features. Marine geophysical surveys conducted in July, 2010, over the Stono and North Edisto River inlets and their riverine inputs south of Charleston, South Carolina, showed 10- to 40-m-wide, 1- to 6-nT magnetic anomalies associated with shallow, sand-covered seabed. These anomalies are distinct from system noise but are too narrow to represent basement features. The anomalies are present mostly in shallow areas where river sediments originating from upland areas enter the inlets. Surface grab samples from the North Edisto River contain trace amounts of heavy mineral sediments including hematite, maghemite, ilmenite, and magnetite, as well as garnet, epidote, zircon, and rutile. Previous stream sediment analyses show enhanced titanium over much of the Atlantic Coastal Plain. The combined data suggest that the anomalies are generated by titanium- and iron-rich heavy mineral sands ultimately originating from the Piedmont and Blue Ridge provinces, which are then reworked and concentrated by tidal currents.

South Carolina↗
USGS2013

Methods and spatial extent of geophysical Investigations, Mono Lake, California, 2009 to 2011

This report summarizes the methods and spatial extent of geophysical surveys conducted on Mono Lake and Paoha Island by U.S. Geological Survey during 2009 and 2011. The surveys include acquisition of new high resolution seismic reflection data, shipborne high resolution magnetic data, and ground magnetic and gravity data on Paoha Island. Several trials to acquire swath bathymetry and side scan sonar were conducted, but were largely unsuccessful likely due to physical properties of the water column and (or) physical properites of the highly organic bottom sediment.

California↗
USGS2014

Geologic and geophysical data for wells drilled at Raft River Valley, Cassia County, Idaho, in 1977-1978 and data for wells drilled previously

In order to better define the size of the thermal anomaly in the Raft River Valley, Idaho, the U.S. Geological Survey drilled a series of intermediate-depth (nominal 500-ft depth) wells in 1977 and 1978. This report presents geologic, geophysical, and temperature data for these drill holes, along with data for five wells drilled by the Idaho National Engineering Laboratory with U.S. Department of Energy Funding. Data previously reported for other drill holes are also included in order to make them available as digital files. For purposes of defining the thermal anomaly for the geothermal system, temperature gradients are calculated over long depth intervals on the basis of the appearance of reasonable linear segments on a temperature versus plot depth. Temperature versus depth data for some drill holes can be represented by a single gradient, whereas others require multiple gradients to match the data. Data for some drill holes clearly reflect vertical flows of water in the formation surrounding the drill holes, and water velocities are calculated for these drill holes. Within The Narrows area, temperature versus depth data show reversals at different depth in different drill holes. In the main thermal area, temperatures in intermediate-depth drill holes vary approximately linearly but with very high values of temperature gradient. Temperature gradients on a map of the area can be reasonable divided into a large area of regional gradients and smaller areas defining the thermal anomalies.

Idaho↗
USGS2015

Geophysical investigation of the pressure field produced by water guns at a pond site in La Crosse, Wisconsin

Three different geophysical sensor types were used to characterize the underwater pressure waves generated by the underwater firing of a seismic water gun and their suitability for establishing a pressure barrier to potentially direct or prevent the movement of the Asian carps. The sensors used to collect the seismic information were blast rated hydrophones and underwater blast sensors. Specific location information for the water guns and the sensors was obtained using either laser rangefinders or differentially corrected global positioning systems (GPS). Two separate studies are discussed in this report. The two studies were completed during September 2012 and July 2013. Both of these studies took place in an earthen testing pond on the campus of Upper Midwest Environmental Sciences Center (UMESC) in La Crosse, Wisconsin. Previous studies had identified 5 pounds per square inch (lb/in 2 ) as a target value for the successful operation of a water gun barrier. The September 2012 study evaluated the performance of 1-cubic-inch (in 3) and 80-in 3 water guns. Data from the 1-in 3 gun showed that it produces a very planar wave with limited effect on the depths above and below its gun ports. The 1-in 3 gun did not produce the 5-lb/in 2 target pressure at a sufficient distance to be considered effective. The 80-in 3 gun produced a bowl-shaped pressure field with the 5-lb/in 2 target radius at the surface extending to 45 feet. The July 2013 study consisted of three scenarios: fish behavior, single gun assessment, and experimental barrier evaluation. The fish behavior scenario simulated the pond conditions from previous studies. Two 80-in 3 water guns were fired in the south end of the testing pond. Pressures essentially doubled from the testing of the single 80-in 3 water gun. The single gun assessment scenario sought to replicate the setup of the 80-in 3 scenario in September 2012, but with additional sensors to better define the pressure field. The 5-lb/in 2 target pressure field continued to show a radius ranging from 40 to 45 feet, dependent on the pressure of the input air. The final scenario, the experimental barrier evaluation, showed that a two-dimensional continuous plane of 5 lb/in 2 can be created between two 80-in 3 water guns to a separation of 99 feet and a depth of 6.5 feet with 1,500 lb/in 2 of input air.

Wisconsin↗
USGS2017

Geophysical data collected during the 2014 minute 319 pulse flow on the Colorado River below Morelos Dam, United States and Mexico

Geophysical methods were used to monitor infiltration during a water release, referred to as a “pulse flow,” in the Colorado River delta in March and April 2014. The pulse flow was enabled by Minute 319 of the 1944 United States–Mexico Treaty concerning water of the Colorado River. Fieldwork was carried out by the U.S. Geological Survey and the Centro de Investigación Científica y de Educación Superior de Ensenada as part of a binational effort to monitor the hydrologic effects of the pulse flow along the limitrophe (border) reach of the Colorado River and into Mexico. Repeat microgravity measurements were made at 25 locations in the southern limitrophe reach to quantify aquifer storage change during the pulse flow. Observed increases in storage along the river were greater with distance to the south, and the amount of storage change decreased away from the river channel. Gravity data at four monitoring well sites indicate specific yield equal to 0.32±0.05. Electromagnetic induction methods were used at 12 transects in the limitrophe reach of the river along the United States– Mexico border, and farther south into Mexico. These data, which are sensitive to variation in soil texture and water content, suggest relatively homogeneous conditions. Repeat direct-current resistivity measurements were collected at two locations to monitor groundwater elevation. Results indicate rapid groundwater-level rise during the pulse flow in the limitrophe reach and smaller variation at a more southern transect. Together, these data are useful for hydrogeologic characterization and hydrologic model development. Electronic data files are provided in the accompanying data release (Kennedy and others, 2016a).

Arizona, Baja California, California↗
USGS2023

The enigmatic Rattlesnake Knoll, Spring Valley, east-central Nevada—A geophysical perspective

Rattlesnake Knoll is a small, 30-meter-high mound of igneous breccia in the center of Spring Valley, east-central Nevada. In the past, researchers have disagreed as to whether the unusual-looking outcrop is intrusive or volcanic. The breccia possesses a normal magnetic polarity, but this is not apparent in aeromagnetic survey data. These data instead show that the knoll lies within a small aeromagnetic low that partially overlaps the extent of a small gravity high. The small gravity anomaly associated with the knoll, combined with an initial, limited ground magnetic survey taken at the knoll, indicates that the knoll rocks extend northward in the subsurface. A second, more extensive ground magnetic traverse was also done north of the knoll. Taking into consideration these new survey data and preexisting data, a two and one-half dimensional modeling program based on Webring (1985) was used to produce a geophysical model that accounts for gravity and magnetic properties, satisfies available geologic information, and conforms to current estimates of basin thickness. This model and the field observations support the interpretation that the knoll consists of gently west-dipping beds of Tertiary volcanic flow breccia, mudflow breccia, and conglomerate.

Nevada↗
USGS2024

Results of 2018–19 water-quality and hydraulic characterization of aquifer intervals using packer tests and preliminary geophysical-log correlations for selected boreholes at and near the former Naval Air Warfare Center Warminster, Bucks County, Pennsylvania

The U.S. Geological Survey (USGS) collected data on the vertical distribution of hydraulic head, specific capacity, and water quality using aquifer-interval-isolation tests and other vertical profiling methods in 15 boreholes completed in fractured sedimentary bedrock in Northampton, Warminster, and Warwick Townships, Bucks County, Pennsylvania during 2018–19. This work was done, in cooperation with the U.S. Navy, to support detailed investigations at and near the former Naval Air Warfare Center (NAWC) Warminster, where groundwater contamination with per- and polyfluoroalkyl substances (PFAS) had become a concern since 2014. Two PFAS compounds, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been measured in groundwater samples from supply and monitoring wells at or near NAWC Warminster in concentrations above U.S. Environmental Protection Agency health advisory levels for drinking water. The area is underlain by the Triassic Stockton Formation, which predominantly consists of sandstone interbedded with shale and siltstone beds and forms a layered fractured-rock aquifer used for private, industrial, and public drinking water supply. The vertical distribution of aquifer properties and water quality was assessed through hydraulic tests and sampling of aquifer intervals using a straddle-packer system (13 boreholes) or depth-discrete point sampling under known borehole-flow conditions (2 boreholes). Geophysical and video logs collected by USGS during 2017–19 were used to identify potential water-bearing fractures in 15 boreholes, which ranged in depth from 210 to 604 feet (ft) and included 6 boreholes drilled in 2018 and 9 existing wells on or near the former NAWC Warminster. Measured borehole flow was predominantly downward in most of the deepest boreholes (greater than 400 ft), which were commonly located at the highest land-surface elevations, with inflow from fractures at relatively shallow depths and outflow through fractures near or below depths of 500 ft below land surface. Hydraulic head differences measured during packer tests were up to about 60 ft between shallow and deep intervals. Borehole flow was predominantly upward in most boreholes less than 400 ft in depth and farther from, and at lower land-surface elevations than, the former NAWC Warminster. Total borehole specific capacity ranged from about 0.07 to 41 gallons per minute per foot [(gal/min)/ft]. Specific-capacity values for individual intervals ranged from 0.02 to 40.0 (gal/min)/ft, with a median of 1.14 (gal/min)/ft and a large range in values at most depths. Differences in water quality of samples as indicated by field properties (pH, dissolved oxygen, and specific conductance) and concentrations of dissolved major ions, PFOA, and PFOS were apparent among isolated intervals in the boreholes. Summed concentrations of PFOA and PFOS ranged from about 11 to 10,780 nanograms per liter (ng/L) and were greater than the 2016 U.S. Environmental Protection Agency health advisory of 70 ng/L for summed PFOA and PFOS concentrations in 62 of 104 intervals and discrete depths tested. The mass ratio of PFOS to PFOA was generally higher than 1.0 in samples with summed PFOA and PFOS concentrations greater than 70 ng/L, with ratio values as high as 8.7. In many boreholes, summed concentrations of PFOA and PFOS were positively related to chloride concentrations, which were elevated above natural-background values [less than 10 milligrams per liter] in most samples and as high as 717 milligrams per liter. Sources of the elevated chloride other than, or in addition to, common rock salt (sodium chloride) were indicated by chloride to sodium molar ratios greater than 1.0. Water-quality data indicated that sampled water from some intervals with lower hydraulic heads may be affected by water from intervals with higher hydraulic heads because of vertical flow in open boreholes; samples from these intervals with lower hydraulic heads may not be fully representative due to some component of cross contamination and should be interpreted with caution. Through a preliminary correlation of natural gamma and resistivity logs of boreholes drilled at and near the former NAWC Warminster, 11 lithologic units were identified and interpreted to strike northeast and dip to the northwest. Hydraulic heads were generally highest in isolated intervals that intercepted beds which, when projected up dip, crop out at the highest land-surface elevation on the former NAWC Warminster, indicating that the dipping-bed structure and topography are factors affecting the distribution of hydraulic head in the aquifer. The hydrogeologic framework in conjunction with the vertical distribution of hydraulic heads and water quality may assist in evaluating the locations of various PFAS sources and potential migration pathways of PFAS in groundwater at and near NAWC Warminster.

Pennsylvania↗
USGS1970

Recommended geophysical investigations of mineral occurrences at Jabal Samran, Al Marasia, and Wutaileh

A familiarization and reconnaissance trip was made in the vicinity of Jabal Samran during 7-8 April 1968. The trip was suggested by E. Heaton and W. Liddicoat, Ministry of Petroleum and Mineral Resources for the purpose of inspecting the mineral occurrences at Jabal Samran, Al Marasia, and Wutaileh, and recommending feasible geophysical methods which should be applied to the study of these occurrences.

Al Marasia, Jabal Samran, Wutaileh↗
USGS1975

Geological Survey and selected U.S. Bureau of Mines and Alaska Division of Geological and Geophysical Surveys reports and maps on Alaska released during 1974, indexed by quadrangle

All Geological Survey reports and maps on Alaska published or released to open files during 1974 are listed by the quadrangle (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 2). Also listed are U.S. Bureau of Mines reports on the geology and mineral resources of Alaska, but not those dealing exclusively with other subjects such as economics. Alaska Division of Geological and Geophysical Surveys published reports on geology and mineral resources are listed, but those released to open files are not. This is because all open-file reports and maps were withdrawn in 1974 for revision, consolidation, or assignment of new identification numbers before possible reissue. At the time of preparation of this index I had received so few newly released open-file reports that I felt that including any of them might cause confusion to potential users because of possible duplication of titles or numbers.

Alaska↗