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At least 811 records · Page 45Linked to original sources
USGS2019

Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts

In spring 2016, a 310-foot-deep boring (named MA–FSW 750) was drilled by the U.S. Geological Survey near Nantucket Sound in East Falmouth, Massachusetts, to investigate the hydrogeology of the southern coast of western Cape Cod. Few borings that are drilled to bedrock exist in the area, and the study area was selected to fill a gap between comprehensive geologic datasets inland to the north and marine geophysical data from beneath Nantucket Sound to the south. A permanent monitoring well (MA–FSW 750–0100) was installed in the boring upon the completion of the drilling and core collection. Observations from sediment cores and surface and borehole geophysical measurements were used to delineate three zones relevant to understanding groundwater flow at the study location. Shallow sands and gravels (0–107 feet [ft] below land surface [bls]) underlain by silt-rich fine and very fine sand (107–175 ft bls) form a zone of high permeability underlain by a zone of relatively lower permeability, referred to as the “shallow high-permeability” and “low-permeability” zones, respectively. A sharp lithological contact separating the shallow high-permeability and low-permeability zones may affect vertical flow of groundwater. Fine to coarse sand with intervals of clay and silt from 175 to 300 ft bls represent a deep zone of relatively high permeability, referred to as the “deep high-permeability” zone. A compacted, nonsorted unit (identified as basal till) and the bedrock surface were encountered at 300 and 305 ft bls, respectively. Hydraulic conductivity estimates from nuclear magnetic resonance logs and sediment grain-size distribution analyses indicated that the shallow high-permeability zone contributes substantially to the capacity of the aquifer to transmit groundwater at the study location. Results from geophysical surveys indicate a gradual transition from fresh to saline groundwater in the interval from 105 to 160 ft bls. Freshwater at the study site is present in the saturated unconsolidated sediments only in the 75 ft between 30 ft (the water table) and 105 ft bls in the shallow high-permeability zone. Sediments shallower than 175 ft bls closely resemble the downward fining post-Wisconsinan age deltaic and lacustrine deposits present in many parts of western Cape Cod; sediments deeper than 175 ft appear to be the product of earlier depositional processes more local to the southern coast of western Cape Cod. This study highlights how high-resolution observations of cored material coupled with a multitool geophysical approach can characterize a single boring to help better understand regional glacial history and hydrogeology.

Massachusetts↗
USGS2021

Geophysical and video logs of selected wells at and near the former Naval Air Warfare Center Warminster, Bucks County, Pennsylvania, 2017-19

The U.S. Geological Survey (USGS) collected borehole geophysical and video logs in 17 open-hole wells in Northampton, Warminster, and Warwick Townships, Bucks County, Pennsylvania during 2017–19 to support detailed groundwater 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. The area is underlain by the Triassic Stockton Formation, which forms a fractured-sedimentary-rock aquifer used for private, industrial, and public drinking-water supply. The geophysical and video logs were used to characterize the boreholes and identify potential water-bearing fractures for subsequent detailed investigations. Of the 17 wells that were logged, subsequent investigations were conducted by USGS in 15 wells and included hydraulic tests of discrete water-bearing zones using a straddle-packer system in 13 wells and depth-discrete point sampling in 2 wells. These 15 wells ranged in depth from about 210 to 604 feet (ft) below land surface (bls) and included six new 6-inch diameter wells drilled to initial depths of 600 ft bls on the former NAWC Warminster base property in 2018 and nine 8- to 12-inch diameter existing former production or unused test wells. Partial geophysical or video logs also were collected by USGS during 2018 in two other wells that were not included in subsequent detailed investigations. Most wells had numerous water-bearing fractures or openings throughout the depth of the open boreholes. Most of these water-bearing features appeared to be openings parallel to bedding or high-angle fractures approximately orthogonal to bedding. Casing lengths ranged from about 19 to 93 ft bls. Depth to the ambient water level at the time of logging ranged from about 1.8 ft above land surface in a flowing well to about 55 ft bls. Measured borehole flow was predominantly downward in most of the deepest wells (greater than 400 ft), which were commonly located at the highest land-surface elevations, and contained inflow from fractures at relatively shallow depths and outflow through fractures near or below depths of 500 ft bls. Borehole flow was predominantly upward in most wells less than 400 ft in depth.

Pennsylvania↗
USGS2011

Hydrogeophysical investigations at Hidden Dam, Raymond, California

Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations. The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct-current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach.

California↗
USGS2017

Scenario Evaluator for Electrical Resistivity survey pre-modeling tool

Geophysical tools have much to offer users in environmental, water resource, and geotechnical fields; however, techniques such as electrical resistivity imaging (ERI) are often oversold and/or overinterpreted due to a lack of understanding of the limitations of the techniques, such as the appropriate depth intervals or resolution of the methods. The relationship between ERI data and resistivity is nonlinear; therefore, these limitations depend on site conditions and survey design and are best assessed through forward and inverse modeling exercises prior to field investigations. In this approach, proposed field surveys are first numerically simulated given the expected electrical properties of the site, and the resulting hypothetical data are then analyzed using inverse models. Performing ERI forward/inverse modeling, however, requires substantial expertise and can take many hours to implement. We present a new spreadsheet-based tool, the Scenario Evaluator for Electrical Resistivity (SEER), which features a graphical user interface that allows users to manipulate a resistivity model and instantly view how that model would likely be interpreted by an ERI survey. The SEER tool is intended for use by those who wish to determine the value of including ERI to achieve project goals, and is designed to have broad utility in industry, teaching, and research.

Groundwater↗
USGS2011

Geophysical bed sediment characterization of the Androscoggin River from the former Chlor-Alkali Facility Superfund Site, Berlin, New Hampshire, to the state border with Maine, August 2009

The former Chlor-Alkali Facility in Berlin, New Hampshire, was listed on the U.S. Environmental Protection Agency National Priorities List in 2005 as a Superfund site. The Chlor-Alkali Facility lies on the east bank of the Androscoggin River. Elemental mercury currently discharges from that bank into the Androscoggin River. The nature, extent, and the speciation of mercury and the production of methyl mercury contamination in the adjacent Androscoggin River is the subject of continuing investigations. The U.S. Geological Survey, in cooperation with Region I of the U.S. Environmental Protection Agency, used geophysical methods to determine the distribution, thickness, and physical properties of sediments in the Androscoggin River channel at a small area of an upstream reference reach and downstream from the site to the New Hampshire–Maine State border. Separate reaches of the Androscoggin River in the study area were surveyed with surface geophysical methods including ground-penetrating radar and step-frequency electromagnetics. Results were processed to assess sediment characteristics including grain size, electrical conductivity, and pore-water specific conductance. Specific conductance measured during surface- and pore-water sampling was used to help interpret the results of the geophysical surveys. The electrical resistivity of sediment samples was measured in the laboratory with intact pore water for comparison with survey results. In some instances, anthropogenic features and land uses, such as roads and power lines affected the detection of riverbed properties using geophysical methods; when this occurred, the data were removed. Through combining results, detailed riverbed sediment characterizations were made. Results from ground-penetrating radar surveys were used to image and measure the depth to the riverbed, depth to buried riverbeds, riverbed thickness and to interpret material-type variations in terms of relative grain size. Fifty two percent of the riverbed in the study area was covered with gravel and finer sediments. The electrically resistive river water and sediment in this study area were conducive to the penetration of the ground-penetrating radar and step-frequency electromagnetic signals and allowed for effective sediment characterization by geophysical methods. The reach between the former Chlor-Alkali Facility and the Riverside Dam, had small areas of fine sediment (estimated 11 percent of riverbed area), found on the upstream left bank and the downstream right bank, with an electromagnetic conductivity (31.4 millisiemens per meter (mS/m) maximum) that was higher than the upstream reference reach. The greatest electromagnetic conductivity (195 mS/m), pore-water specific conductance (324 mS/m) and lab measured sediment conductivity of (76.8 mS/m, measured with a direct-current resistivity test box) in the study were measured approximately 1 mile (mi) downstream of the site from a sandbar on the left bank. Reaches adjacent to and within 2 mi downstream from the site had elevated electromagnetic conductivity despite having lower estimated percentages of riverbed area covered in sediment (11, 25, and 61 percent, respectively) than the reference reach (97). Typically finer grained sediment with similar mineralogy will be more conductive. The Shelburne Reservoir is approximately 8 mi downstream from the site had the second greatest pore-water specific conductance measured, 45.8 mS/m. Many of the locations with the largest step-frequency electromagnetic values have not been sampled for pore water and sediment.

New Hampshire↗
USGS2000

Ground geophysical study of the Buckeye mine tailings, Boulder watershed, Montana

The Buckeye mine site is located in the Boulder River watershed along Basin Creek, in northern Jefferson County, Montana. This project is part of the Boulder River watershed Abandoned Mine Lands Initiative, and is a collaborative effort between the U.S. Geological Survey and Bureau of Land Management in the U.S. Department of the Interior, and the U.S. Forest Service in the U.S. Department of Agriculture. The site includes a large flotation milltailing deposit, which extends to the stream and meadows below the mine. These tailings contain elevated levels of metals, such as silver, cadmium, copper, lead, and zinc. Metal-rich fluvial tailings containing these metals, are possible sources of ground and surface water contamination. Geophysical methods were used to characterize the sediments at the Buckeye mine site. Ground geophysical surveys, including electromagnetics, DC resistivity, and total field magnetic methods, were used to delineate anomalies that probably correlate with subsurface metal contamination. Subsurface conductivity was mapped using EM-31 and EM-34 terrain conductivity measuring systems. The conductivity maps represent variation of concentration of dissolved solids in the subsurface from a few meters, to an approximate depth of 30 meters. Conductive sulfides several centimeters thick were encountered in a shallow trench, dug in an area of very high conductivity, at a depth of approximately 1 to1.5 meters. Laboratory measurements of samples of the sulfide layers show the conductivity is on the order of 1000 millisiemens. DC resistivity soundings were used to quantify subsurface conductivity variations and to estimate the depth to bedrock. Total field magnetic measurements were used to identify magnetic metals in the subsurface. The EM surveys identified several areas of relatively high conductivity and detected a conductive plume extending to the southwest, toward the stream. This plume correlates well with the potentiometric surface and direction of ground water flow, and with water quality data from monitoring wells in and around the tailings. The electrical geophysical data suggests there has been vertical migration of high dissolved solids. A DC sounding made on a nearby granite outcrop to the north of the mine showed that the shallow conductivity is on the order of 5 millisiemens/m. Granite underlying the mine tailings, with similar electrical properties as the outcropping area, may be more than 30 meters deep.

Montana↗
USGS2002

Borehole-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut

A borehole-geophysical investigation was conducted to help characterize the hydrogeology of the fractured-rock aquifer and the distribution of unconsolidated glacial deposits near the former landfill and chemical waste-disposal pits at the University of Connecticut in Storrs, Connecticut. Eight bedrock boreholes near the landfill and three abandoned domestic wells located nearby were logged using conventional and advanced borehole-geophysical methods from June to October 1999. The conventional geophysical-logging methods included caliper, gamma, fluid temperature, fluid resistivity, and electromagnetic induction. The advanced methods included deviation, optical and acoustic imaging of the borehole wall, heat-pulse flowmeter, and directional radar reflection. Twenty-one shallow piezometers (less than 50-feet deep) were logged with gamma and electromagnetic induction tools to delineate unconsolidated glacial deposits. Five additional shallow bedrock wells were logged with conventional video camera, caliper, electromagnetic induction, and fluid resistivity and temperature tools. The rock type, foliation, and fracturing of the site were characterized from high-resolution optical-televiewer (OTV) images of rocks penetrated by the boreholes. The rocks are interpreted as fine- to medium-grained quartz-feldsparbiotite-garnet gneiss and schist with local intrusions of quartz diorite and pegmatite and minor concentrations of sulfide mineralization similar to rocks described as the Bigelow Brook Formation on regional geologic maps. Layers containing high concentrations of sulfide minerals appear as high electrical conductivity zones on electromagneticinduction and borehole-radar logs. Foliation in the rocks generally strikes to the northeast-southwest and dips to the west, consistent with local outcrop observations. The orientation of foliation and small-scale gneissic layering in the rocks, however, varies locally and with depth in some of the boreholes. In two of the boreholes, the foliation strikes predominantly to the northwest and dips to the northeast. Although small-scale faults and lithologic discontinuities were observed in the OTV data, no large-scale faults were observed that appear on regional geologic maps. Fractures were located and characterized through the use of conventional geophysical, OTV, acoustic-televiewer (ATV), and borehole-radar logs. The orientation of fractures varies considerably across the site; some fractures are parallel to the foliation, whereas others cross-cut the foliation. Many of the transmissive fractures in the bedrock boreholes strike about N170°E and N320°E with dips of less than 45°. Other transmissive fractures strike about N60°E with dips of more than 60°. Most of the transmissive fractures in the domestic wells strike about N60°E and N22°E with dips of more than 45°. The strike of N60°E is parallel to the trend of a thrust fault that appears on regional geologic maps. Vertical flow in the boreholes was measured with the heat-pulse flowmeter under ambient and (or) pumping conditions. Results of ATV, OTV, and conventional logs were used to locate specific zones for flowmeter testing. Ambient downflow was measured in three boreholes, ambient upflow was measured in two other boreholes, and both ambient downflow and upflow were measured in a sixth borehole. The other five bedrock boreholes and domestic wells did not have measurable vertical flow. The highest rate of ambient flow was measured in the background borehole in which upflow and downflow converged and exited the borehole at a fracture zone near a depth of 62 feet. Ambient flow of about 340 gallons per day was measured. In the other five wells, ambient flow of about 20 to 35 gallons per day was measured. Under low-rate pumping (0.25 to 1 gallon per minute), one to six inflow zones were identified in each well. Usually the fractures that are active under ambient conditions contribute to the well under pumping conditions. To prevent ambient vertical flow and the potential for cross-contamination, temporary borehole liners were installed in five of the boreholes. Specific-capacity and open-hole transmissivity values were determined in eight boreholes completed in bedrock. The specific capacity estimated for these boreholes ranges from 0.14 to 1.6 gallons per minute per foot. The values for open-hole transmissivity range over two orders of magnitude and when proportioned to individual fracture transmissivity, range from 23 to 340 feet squared per day. Two boreholes had been drilled to intersect electrically conductive zones identified by previous surface-geophysical investigations. The borehole-geophysical results indicate that the boreholes penetrate electrically conductive structures consistent with the anomalies interpreted from the surface-geophysical data. Borehole MW121R was located to intersect a dipping electrically conductive anomaly at about 60 feet, interpreted from the two-dimensional direct currentresistivity survey conducted on the western side of the landfill. The electromagnetic-conductivity log in the borehole contains a high electrical conductivity anomaly at a depth of 69 feet. The magnitude of this anomaly is nearly 10,000 millisiemens per meter and is coincident with a layer containing sulfide mineralization, rather than fractures. The other borehole, MW105R, was located to intersect another anomaly south of the landfill. This anomaly was interpreted as a north-south striking, westward dipping feature. In the borehole, two south-striking, westward dipping fractures were identified in the ATV, OTV, and radar logs. The specific conductance of the fluid measured near these fractures was as high as 1,250 microsiemens per centimeter. Water-quality samples collected in October 1999 from an isolated zone from 71.5 to 76.5 feet indicated high specific conductance (810 microsiemens per centimeter), high concentrations of iron and cadmium, negative oxidation-reduction potential, and chlorobenzene. Collectively, these parameters indicate that the high specific conductance in the borehole logs for MW105R was caused by landfill leachate. Therefore, the anomaly identified by boreholeand surface-geophysical surveys is interpreted as a conductive lithologic feature and a permeable fracture zone that contains landfill leachate.

Connecticut↗
USGS2003

Archive of chirp seismic reflection data collected during USGS cruises 01SCC01 and 01SCC02, Timbalier Bay and offshore East Timbalier Island, Louisiana, June 30 - July 9 and August 1 - 12, 2001

In June, July, and August of 2001, the U.S. Geological Survey (USGS), in cooperation with the University of New Orleans, the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources, conducted a shallow geophysical and sediment core survey of Timbalier Bay and the Gulf of Mexico offshore East Timbalier Island, Louisiana. This report serves as an archive of unprocessed digital seismic reflection data, trackline navigation files, trackline navigation maps, observers' logbooks, Geographic Information Systems (GIS) information, and formal Federal Geographic Data Committee (FGDC) metadata. In addition, a gained digital Graphics Interchange Format (GIF) image of each seismic profile is provided. Please see Kulp and others (2002), Flocks and others (2003), and Kulp and others (in prep.) for further information about the sediment cores collected and the geophysical results. For convenience, a list of acronyms and abbreviations frequently used in this report is also included. This Digital Versatile Disc (DVD) document is readable on any computing platform that has standard DVD driver software installed. Documentation on this DVD was produced using Hyper Text Markup Language (HTML) utilized by the World Wide Web (WWW) and allows the user to access the information using a web browser (i.e. Netscape, Internet Explorer). To access the information contained on these discs, open the file 'index.htm' located at the top level of each disc using a web browser. This report also contains WWW links to USGS collaborators and other agencies. These links are only accessible if access to the internet is available while viewing these DVDs. The archived chirp seismic reflection data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry et al., 1975) and may be downloaded for processing with public domain software such as Seismic Unix (SU), currently located at http://www.cwp.mines.edu/cwpcodes/index.html. Examples of SU processing scripts are provided in the CHIRP.tar file located in the SU subfolder of the SOFTWARE folder located at the top level of each disc. In-house (USGS) DOS and Microsoft Windows compatible software for viewing SEG-Y headers - DUMPSEGY.EXE (Zihlman, 1992) - is provided in the USGS subfolder of the SOFTWARE folder. Processed profile images, trackline navigation maps, logbooks, and formal metadata may be viewed with a web browser.

Louisiana↗
USGS2002

Detection and mapping of fractures and cavities using borehole radar

Borehole radar can be used in a single-hole reflection mode or in a cross-hole tomography mode. In the reflection mode, radar provides an image of discontinuities in the bedrock surrounding a borehole, including bedding planes, lithologic contacts, fractures, and cavities. The measurements are either directional or omni-directional, depending upon the type of equipment and antennas. In the tomography mode, where the transmitter and receiver are in separate boreholes, radar provides an image of the planar section between the boreholes. The radius of investigation depends on the antenna frequency and the electrical conductivity of the bedrock. For a central frequency of 100 megahertz, in the reflection mode the ranges are typically 10 to 40 meters in resistive solid rock and less than 5 meters in conductive, clay-rich, or silty rock. Single-hole and cross-hole radar also have been used for water-supply investigations in the northeast-ern United States. Borehole radar was used to investigate crystalline bedrock in two rapidly developing com-munities that rely on water resources in the bedrock. The surveys were conducted and interpreted along with data from other borehole geophysical tools. The borehole radar surveys were used to identify the location and orientation of reflectors, locate the primary pathways of flow to the supply wells, and identify aquifer character-istics that may be useful in siting a production well and protecting high-yielding wells in crystalline rocks. Borehole radar has been used to investigate fractures, cavities, and lithologic changes at several sites in Europe. The radar data has been interpreted in conjuction with the results of modeling of borehole-radar re-sponse. At the Grimsel nuclear waste laboratory in Switzerland, single-hole reflection and tomography methods were used to characterize the rock in inclined boreholes. At numerous geotechnical sites in Belgium, France, and the Netherlands, borehole radar has been used to characterize the rock and identify fractures and cavities.

Conference Paper↗
USGS2003

Archive of boomer seismic reflection data collected during USGS cruises 01SCC01 and 01SCC02, Timbalier Bay and offshore East Timbalier Island, Louisiana, June - August, 2001

In June, July, and August of 2001, the U.S. Geological Survey (USGS), in cooperation with the University of New Orleans (UNO), the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources, conducted a shallow geophysical and sediment core survey of Timbalier Bay and the Gulf of Mexico offshore East Timbalier Island, Louisiana. This report serves as an archive of unprocessed digital seismic reflection data, trackline navigation files, trackline navigation maps, observers' logbooks, Geographic Information Systems (GIS) information, and formal Federal Geographic Data Committee (FGDC) metadata. In addition, a filtered and gained digital Graphics Interchange Format (GIF) image of each seismic profile is provided. Please see Kulp and others (2002), Flocks and others (2003), and Kulp and others (in prep.) for further information about the sediment cores collected and the geophysical results. For convenience, a list of acronyms and abbreviations frequently used in this report is also included. This Digital Versatile Disc (DVD) document is readable on any computing platform that has standard DVD driver software installed. Documentation on this DVD was produced using Hyper Text Markup Language (HTML) utilized by the World Wide Web (WWW) and allows the user to access the information using a web browser (i.e. Netscape, Internet Explorer). To access the information contained on this disc, open the file 'index.htm' located at the top level of the disc using a web browser. This report also contains WWW links to USGS collaborators and other agencies. These links are only accessible if access to the Internet is available while viewing this DVD. The archived boomer seismic reflection data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry et al., 1975) and may be downloaded for processing with public domain software such as Seismic Unix (SU), currently located at http://www.cwp.mines.edu/cwpcodes/index.html. Examples of SU processing scripts are provided in the BOOM.tar file located in the SU subfolder of the SOFTWARE folder located at the top level of this disc. In-house (USGS) DOS and Microsoft Windows compatible software for viewing SEG-Y headers - DUMPSEGY.EXE (Zihlman, 1992) - is provided in the USGS subfolder of the SOFTWARE folder. Processed profile images, trackline navigation maps, logbooks, and formal metadata may be viewed with a web browser.

Louisiana↗
USGS2017

Hydrogeophysical investigations of earthen dams – Two California case studies

Excessive groundwater seepage can be a common engineering concern with earthen dams. The application of geophysical methods, whether for characterization or for long-term monitoring, to help inform mitigation strategies is becoming a more common addition to these investigations. The U.S. Geological Survey (USGS) has completed geophysical investigations at several earthen dams in cooperation with the U.S. Army Corps of Engineers (USACE) to help characterize subsurface hydrogeologic conditions and to identify potential sources of seepage. Summaries of the investigations of Martis Creek Dam and Hidden Dam, both located in California, are presented.

California↗
USGS2007

Characterizing infiltration through a mine-waste dump using electrical geophysical and tracer-injection methods, Clear Creek County, Colorado

Infiltration of surface water through mine waste can be an important or even dominant source of contaminants in a watershed. The Waldorf mine site in Clear Creek County, Colorado, is typical of tens of thousands of small mines and prospects on public lands throughout the United States. In this study, electromagnetic (EM) conductivity and direct current (dc) resistivity surveys were conducted in tandem with a NaCl tracer study to delineate ground-water flow paths through a mine-waste dump and adjacent wetland area. The tracer was used to tag adit water infiltrating from braided channels flowing over the top of the dump to seeps at the base of the dump. Infiltration from the braided channels had a maximum flow rate of 92 m/day and a hydraulic conductivity of 1.6 × 10 4 cm 3 /s. After rerouting of adit flow around the waste dump, discharge at some of the largest seeps was reduced, although not all seepage was eliminated entirely. Integrating results of the tracer study with those of the EM and dc geophysical surveys revealed two main flow paths of ground water, one beneath the dump and one through the dump. The main source of water to the first flow path is deeper ground water emerging from the fault zone beneath the collapsed adit. This flow path travels beneath the waste dump and appears to have been unaffected by rerouting of the adit discharge around the waste dump. The source of the second flow path is infiltration of adit water from braided channels flowing over the top of the dump, which is intermediate in depth and flows through the center of the waste dump. Following rerouting of adit flow, discharge to seeps at the toe of the dump along this flow path was reduced by as much as two-thirds, although not eliminated entirely. Improved understanding of ground-water flow paths through this abandoned mine site is important in developing effective remediation strategies to target sources of metals emanating from the adit, waste dump, and contaminated wetland area. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government.

Colorado↗
USGS1975

Geophysical logs from a geologic test hole near Charleston, South Carolina

On March 2, 1975, the U.S. Geological Survey completed a series of geophysical well logs in the Charleston Project Deep Core Hole No. 1 located at Latitude 32° 53.2 'N and Longitude 80° 21 . 5'W in Dorchester County near Charleston, South Carolina. The land surface is at an elevation of 5.4 m (18 ft) above mean sea level. The total depth of the test hole is 793 m (2,600 ft) and the geophysical logs were recorded through fresh barite mud to the bottom. The deep geologic. test hole penetrated the entire section of Atlantic Coastal Plain sediments and extended about 40 m (130 ft) into basement rock composed of basalt flows. The purpose of the logging is to assist in the interpretation of the depositional environments, stratigraphy, structural, and geological history of the onshore and offshore areas surrounding Charleston, S.C. The purpose of this report is to make the uninterpretated geophysical recordings of the entire log suite publicly available . The logs available are shown in table 1, along with the operating depth intervals, total footage, scale, units of measure, combination log, and other pertinent data.

South Carolina↗
USGS1981

Samples from the United States eastern continental margin collected by the U.S. Geological Survey

As part of the National Geophysical and Solar-Terrestrial Data Center's (NGSDC's) project to maintain a computer-accessed list of marine geological samples, the U.S. Geological Survey has inventoried 3,949 samples from the continental margin of the Eastern United States (Fig. 1). Most (3,868) of these samples are grab and dredge samples collected by the U.S. Geological Survey in an earlier cooperative program with the Woods Hole Oceanographic Institution (WHOI) and are stored at WHOI. Samples collected since 1974 are stored by the U.S. Geological Survey. This more recent collection is made up of 3,815.5 m of rotary-drilled cores collected at 19 stations in 1976 by the drill ship GLOMAR CONCEPTION, 243.8 m of piston cores and 38.3 m of gravity cores collected during the 1979 and 1980 cruises of the R/V ENDEAVOR, and &grab samples collected by the M/V STATE ARROW in 1978.

United States eastern continental margin↗
USGS1952

A magnetic anomaly near Bear Lake, Houghton County, Michigan

A large magnetic anomaly of unknown origin occurs about 1 1/2 miles east of Bear Lake, Houghton County, Michigan, in secs. 24 and 258 T. 56 N., R. 34 W. The occurrence is isolated in an area of very weakly magnetic rocks and has special geologic interest because it is adjacent to a non-magnetic rhyolite porphyry body that is stratigraphically higher than any other known igneous rock in the Keweenawan series. An aeromagnetic survey of the Michigan copper district by the Geophysics Branch of the U. S. Geological Survey in 1948 first revealed the anomaly (Fig. 1). The anomalous area has been more fully outlined by a dip-needle survey, and briefly discusses the geology of the area and possible significance of the anomaly.

Michigan↗
USGS1997

Identification of potential water-bearing zones by the use of borehole geophysics in the vicinity of Keystone Sanitation Superfund Site, Adams County, Pennsylvania, and Carroll County, Maryland

Between April 23, 1996, and June 21, 1996, the U.S. Environmental Protection Agency contracted Haliburton-NUS, Inc., to drill four clusters of three monitoring wells near the Keystone Sanitation Superfund Site. The purpose of the wells is to allow monitoring and sampling of shallow, intermediate, and deep waterbearing zones for the purpose of determining the horizontal and vertical distribution of any contaminated ground water migrating from the Keystone Site. Twelve monitoring wells, ranging in depth from 50 to 397.9 feet below land surface, were drilled in the vicinity of the Keystone Site. The U.S. Geological Survey conducted borehole-geophysical logging and determined, with geophysical logs and other available data, the ideal intervals to be screened in each well. Geophysical logs were run on four intermediate and four deep wells, and a caliper log only was run on shallow well CL-AD-173 (HN-1S). Interpretation of geophysical logs and existing data determined the placement of screens within each borehole.

Maryland, Pennsylvania↗
USGS2019

Discovering blind geothermal systems in the Great Basin Region: An integrated geologic and geophysical approach for establishing geothermal play fairways: All phases

Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising areas for new development. This project integrated multiple datasets to apply the play fairway concept and assess geothermal potential in a large region of the Great Basin in Nevada. It is therefore referred to as the Nevada play fairway project. This project was a strong collaborative effort between several organizations, led by the Nevada Bureau of Mines and Geology at the University of Nevada, Reno, but with key support from the U.S. Geological Survey, ATLAS Geosciences, Inc,, Hi-Q Geophysical, Inc., Lawrence Berkeley National Laboratory, Utah Geological Survey, and Innovative Geothermal Ltd. In Budget Period 1 of this project, available data for nine geologic, geochemical, and geophysical parameters were initially synthesized to produce a new detailed geothermal potential map of 96,000 km2 from west-central to eastern Nevada (Figure 1). These parameters were grouped into subsets and individually weighted (Figure 2) to delineate rankings for local permeability, intermediate permeability, regional permeability, and thermal potential, which collectively defined geothermal play fairways (i.e., most likely locations for significant geothermal fluid flow). This initial work was aimed at reducing the risks in regional exploration and therefore facilitating discovery of new commercial-grade systems in blind settings, as well as in areas with surface expressions of geothermal activity. Budget Period 2 of the project involved detailed analysis of some of the most promising areas identified in Phase 1. Twenty-four highly prospective areas, including both known undeveloped systems and previously undiscovered potential blind systems, were identified for further analysis (Figures 3 and 4). After reconnaissance of these areas, five of the most promising sites were selected for detailed studies. Multiple techniques were employed in the detailed studies, including geologic mapping, shallow temperature surveys, gravity surveys, Lidar, geochemical studies, seismic reflection analysis, and 3D modeling. The goal of the detailed studies was to identify specific areas with the highest likelihood for high permeability and thermal fluids, such that drill sites could be targeted. Three main sets of predictive maps were generated for each detailed study area: 1) play fairway maps, 2) play fairway error maps, and 3) direct evidence maps. Local- and intermediate-scale permeability models were revised to reflect results of the detailed geologic, geophysical, and geochemical analyses. Budget Period 3 of the project involved more detailed geophysical analyses and temperature-gradient (TG) drilling in southeastern Gabbs Valley and northern Granite Springs Valley (Figure 4), deemed the two most promising sites, with the goal of providing preliminary validation of the play fairway methodology. In southeastern Gabbs Valley, the collocation of a favorable structural setting (displacement transfer zone and fault intersections), Quaternary faults, intersecting and terminating gravity gradients, magnetic low, shallow (2 m) temperature anomaly, low resistivity anomaly, and promising geothermometry from nearby water wells provided evidence for a blind system. Drilling of six TG holes defines an apparent geothermal system at this locality with temperatures as high as 124°C at 152 m. This system is blind, with no surface hot springs, fumaroles, or paleo-geothermal deposits. For northern Granite Springs Valley, a favorable structural setting (termination of a major Quaternary normal fault), terminating gravity gradient, magnetic gradient, newly discovered sinter deposits, nearby warm water wells, previously drilled TG holes in the vicinity, and promising geothermometry suggest a hidden system. Drilling of six new TG holes yields temperatures of ~96°C at ~250 m, suggesting the presence of a geothermal system. Major lessons learned in the course of this project include: 1) initially identified sites commonly include multiple favorable structural settings at a finer scale; 2) promising sites in Cenozoic basins cannot be recognized without detailed geophysical surveys; and 3) play fairway analysis should be refined as the exploration program vectors into the most promising sites and finer-scale data are acquired. In addition to producing copious amounts of data, this project resulted in 16 published papers, 10 abstracts, more than 40 presentations across the U.S. and abroad (including several keynote addresses), 2 Masters theses, and 7 media reports.

Nevada↗
USGS2018

Ground penetrating radar and differential global positioning system data collected in April 2016 from Fire Island, New York

Researchers from the U.S. Geological Survey (USGS) conducted a long-term coastal morphologic-change study at Fire Island, New York, prior to and after Hurricane Sandy impacted the area in October 2012. The Fire Island Coastal Change project objectives include understanding the morphologic evolution of the barrier island system on a variety of time scales (months to centuries) and resolving storm-related impacts, post-storm beach response, and recovery. In April 2016, scientists from the USGS St. Petersburg Coastal and Marine Science Center conducted geophysical and sediment sampling surveys on Fire Island to characterize and quantify spatial variability in the subaerial geology with the goal of subsequently integrating onshore geology with other surf zone and nearshore datasets. This report, along with the associated USGS data release , serves as an archive of ground penetrating radar (GPR) and post-processed differential global positioning system (DGPS) data collected from beach and back-barrier environments on Fire Island, April 6–13, 2016 (USGS Field Activity Number 2016-322-FA). Data products, including unprocessed GPR trace data, processed DGPS data, elevation-corrected subsurface profile images, geographic information system files, and accompanying Federal Geographic Data Committee metadata are available for download.

New York↗