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At least 253 records · Page 14Linked to original sources
USGS1985

NORTH AMERICAN DATUM 1983 IMPLEMENTATION IMPACTS ON THE USGS NATIONAL MAPPING PROGRAM.

The U. S. Geological Survey has previously experienced the impacts on the National Mapping Program that are associated with implementing a readjustment of the horizontal datum. The impacts of these past readjustments were minimal compared to those of the current readjustment. The Geological Survey currently has produced and published over 60,000 different map products. The 7. 5-minute mapping program is nearing completion with over 85 percent of the conterminous States mapped. The intermediate-scale mapping program of the conterminous United States is scheduled for completion of planimetric editions by the end of 1986. It is apparent that until digital cartographic data are available, implementation of the North American Datum 1983 will primarily consist of cartographic adjustment of existing map products.

Conference Paper↗
USGS2006

The fifth International Geological Congress, Washington, 1891

The 5th International Geological Congress (IGC), the initial meeting in North America, was the first of the three IGCs that have been held in the United States of America (USA). Of the 538 registrants alive when the 5th IGC convened in Washington, 251 persons, representing fifteen countries, actually attended the meeting. These participants included 173 people from the USA, of whom forty-two represented the US Geological Survey (USGS). Fourteen of the US State geological surveys sent representatives to Washington. Eight participants came from other countries in the Western Hemisphere - Canada (3), Chile (1), Mexico (3), and Peru (1). The sixty-six European geologists and naturalists at the 5th IGC represented Austro-Hungary (3), Belgium (3), Britain (12), France (7), Germany (23), Norway (1), Romania (3), Russia (8), Sweden (4), and Switzerland (2). The USGS and the Columbian College (now the George Washington University) acted as the principal hosts. The American Association for the Advancement of Science and then the Geological Society of America (GSA) met in the Capital immediately before the Congress convened (26 August-1 September 1891). The 5th IGC's formal discussions treated the genetic classification of Pleistocene rocks, the chronological correlation of clastic rocks, and the international standardization of colors, symbols, and names used on geologic maps. The third of those topics continued key debates at the 1st through 4th IGCs. The GSA, the Korean Embassy, the Smithsonian Institution's US National Museum, the USGS, and one of the two Secretaries-General hosted evening receptions. Field excursions examined Paleozoic exposures in New York (18-25 August), Cretaceous-Pleistocene localities along the Potomac River south of Washington (30 August), and classic Precambrian-Pleistocene sequences and structures in the Great Plains, Yellowstone, Rocky Mountains, and Great Basin (2-26 September), with optional trips to the Grand Canyon (19-28 September) and Lake Superior (23 September-2 October). The single-volume report of the 5th IGC was published in Washington in 1893.

Conference Paper↗
USGS2001

Occurrence of selected radionuclides in ground water used for drinking water in the United States: A reconnaissance survey, 1998

The U.S. Geological Survey, in collaboration with the U.S. Environmental Protection Agency, the American Water Works Association, and the American Water Works Service Company, completed a targeted national reconnaissance survey of selected radionuclides in public ground-water supplies. Radionuclides analyzed included radium-224 (Ra-224), radium-226 (Ra-226), radium-228 (Ra-228), polonium-210 (Po-210) and lead-210 (Pb-210).This U.S. Geological Survey reconnaissance survey focused intentionally on areas with known or suspected elevated concentrations of radium in ground water to determine if Ra-224 was also present in the areas where other isotopes of radium had previously been detected and to determine the co-occurrence characteristics of the three radium isotopes (Ra-224, Ra-226, and Ra-228) in those areas. Ninety-nine raw-water samples (before water treatment) were collected once over a 6-month period in 1998 and 1999 from wells (94 of which are used for public drinking water) in 27 States and 8 physiographic provinces. Twenty-one of the 99 samples exceeded the current U.S. Environmental Protection Agency drinking-water maximum contaminant level of 5 picocuries per liter (pCi/L) for combined radium (Ra-226 + Ra-228). Concentrations of Ra-224 were reported to exceed 1 pCi/L in 30 percent of the samples collected, with a maximum concentration of 73.6 pCi/L measured in water from a nontransient, noncommunity, public-supply well in Maryland. Radium-224 concentrations generally were higher than those of the other isotopes of radium. About 5 percent of the samples contained concentrations of Ra-224 greater than 10 pCi/L, whereas only 2 percent exceeded 10 pCi/L for either Ra-226 or Ra-228. Concentrations of Ra-226 greater than 1 pCi/L were reported in 33 percent of the samples, with a maximum concentration of 16.9 pCi/L measured in water from a public-supply well in Iowa. Concentrations of Ra-228 greater than 1 pCi/L were reported in 22 samples, with a maximum concentration of 72.3 pCi/L measured in water from a non-transient, noncommunity, public-supply well in Maryland.Radium-224, which is a decay product of Ra-228 in the Th-232 decay series, was significantly correlated with Ra-228 (Spearman?s rank correlation coefficient ?r? equals 0.82) and to a lesser degree with Ra-226 (r equals 0.69), which is an isotope in the U-238 decay series. The rank correlation coefficient between Ra-226 and Ra-228 was 0.63. The high correlation between Ra-224 and Ra-228 concentrations and the corresponding isotopic ratios of the two (about 1:1 in 90 percent of the samples) indicates that the two radionuclides occur in approximately equal concentrations in most ground water sampled. Thus, Ra-228 can be considered as a reasonable proxy indicator for the occurrence of Ra-224 in ground water.The maximum concentration of Po-210 was 4.85 pCi/L and exceeded 1 pCi/L in only two samples. The maximum concentration of Pb-210 was 4.14 pCi/L, and about 10 percent of the samples exceeded 1 pCi/L. Areas with known, or suspected, elevated concentrations of polonium and lead were not targeted in this survey.Three major implications are drawn for future radionuclide monitoring on the basis of this information: (1) grossalpha particle analyses of ground water should be done within about 48-72 hours after collection to determine the presence of the short-lived, alpha-particle emitting isotopes, such as Ra-224, which was detected in elevated concentrations in many of the samples collected for this survey; (2) the isotope ratios of Ra-224 to Ra-228 in ground water are variable on a national scale, but the two radioisotopes generally occur in ratios near 1:1, therefore, the more commonly measured Ra-228 can be used as an indicator of Ra-224 occurrence for some general purposes other than compliance; and (3) the isotopic ratios of Ra-226 to Ra-228 were less than 3:2 in many samples. These ratios corroborate results of previous studies that have shown the presence of Ra-228.

Water-Resources Investigations Report↗
USGS1974

Summary of activities, U.S. Geological Survey Saudi Arabian project, 1950 to 1974

The U. S. Geological Survey (USGS) first began work in the Kingdom of Saudi Arabia in 1950 under the sponsorship of the Ministry of Finance and National Economy. The basic objective of the work was to investigate the mineral and water resource potential in western Saudi Arabia, but little was known of the region and it therefore was necessary to prepare geographic and geologic maps. Aerial photographs were taken and controlled mosaics produced, some paid for by the USGS but most paid for by the Saudi Arabian government, and reconnaissance geologic mapping was undertaken until the USGS team left Saudi Arabia in 1955. This mapping, in cooperation with mapping of the Arabian American Oil Company, was compiled as a series of scale 1:500,000 geographic and geologic maps in Arabic and English covering all of Saudi Arabia. A total of 42 of these maps were prepared. Three scale 1:2,000,000 geographic and geologic maps in Arabic and English, covering the Arabian Peninsula, also were prepared from this work. All of the maps were printed in the United States and published by the USGS, the last in 1963. Other work done by the USGS between 1950 and 1955 included locating and examining ancient mines, indentifying the Wadi Fatima oolitic iron deposit and other iron deposits in northwest Saudi Arabia, and advising on many water supply problems including those for Riyadh, Qizan, Qunfudhah, Rabigh, Yenbo, Umm Lejh, and Al Wajh. The mapping work and the geologic investigations laid the groundwork for the more detailed studies that followed.

Open-File Report↗
USGS1999

Ten years of studies on Maryland's inner Continental Margin and coastal bays

During the past ten years of the Association of American State Geologists-Mineral Management Service Continental Margins Program, the Maryland Geological Survey investigated the sedimentological, paleontological, stratigraphical and geophysical character of Maryland's inner continental shelf. Based on seismic records and sedimentological analyses completed during the first four years, a late Quaternary stratigraphic model was developed. Five distinct stratigraphic units were identified and described on the Maryland inner shelf. These units represent late Pleistocene interglacial deposits, the oldest of which corresponds to pre-Illinoian (oxygen-isotope stages 7 and/or 9) transgressive shelf sands. Overlying the Q1 unit, the Q2 unit is a 6-meter thick mud sequence of oxygen-isotope stage 5 (128-75 ka) age. Units Q3 and Q4 representing fluvial and leading edge estuarine deposits (oxygen-isotope stages 4, 3 and 2) filled numerous paleochannels that were incised into units Q2 and Q1. Modern trailing-edge transgressive shelf shoals (Unit Q5) discontinuously cap the sequence. The 5th and 6th years studies reported on the economic minerals of surficial and cored sediments. Vibracores collected off the Maryland's shelf during previous studies were analyzed for mineral types and abundances, weight percent of general size fractions, and heavy mineral (HM) content. Mineralogic maturity indices were compiled to correlate the THM and economic heavy minerals (EHM) abundances with position offshore, sediment type, and the indices themselves. For the 7th year, the Maryland Geological Survey re-examined geophysical records and lithological data originally collected by the Army Corps of Engineers to locate and assess beach fill borrow areas for the Ocean City Beach Replenishment Project. Data from 163 vibracores and over 300 kilometers of high-resolution seismic profile records collected off Ocean City, Maryland, supported the stratigraphic model developed by MGS during the first four years of the AASG-MMS program. The Maryland coastal bays became the focus of study during the 8th and 9th years during which seismic records, cores and surficial sediment were collected in Isle of Wight and Assawoman Bays. Shallow pretransgression surface was mapped, relating the existing streams to offshore paleochannels. The tenth year study focused on developing a repository for vibracores collected on Maryland's inner continental shelf.During the past ten years of the Association of American State Geologists-Mineral Management Service Continental Margins Program, the Maryland Geological Survey investigated the sedimentological, paleontological, stratigraphical and geophysical character of Maryland's inner continental shelf. Based on seismic records and sedimentological analysis completed during the first four years, a late quaternary stratigraphic model was developed. Five distinct stratigraphic units were identified and described on the Maryland inner shelf. These units represent late Pleistocene interglacial deposits, the oldest of which corresponds to pre-Illinoian transgressive shelf sands.

Marine Georesources and Geotechnology↗
USGS2014

Appendix A—A selected list of papers relating to ground‐water hydrology

In the following list, brief‐statements have been added to certain references to call attention to special phases of ground‐water problems which are not apparent from the titles. Abstracts of most of the papers have been or will be published in the Annotated Bibliography of Economic Geology.

Eos, Transactions, American Geophysical Union↗
USGS2011

SICS: the Southern Inland and Coastal System interdisciplinary project of the USGS South Florida Ecosystem Program

State and Federal agencies are working jointly on structural modifications and improved water-delivery strategies to reestablish more natural surface-water flows through the Everglades wetlands and into Florida Bay. Changes in the magnitude, duration, timing, and distribution of inflows from the headwaters of the Taylor Slough and canal C-111 drainage basins have shifted the seasonal distribution and extent of wetland inundation, and also contributed to the development of hypersaline conditions in nearshore embayments of Florida Bay. Such changes are altering biological and vegetative communities in the wetlands and creating stresses on aquatic habitat. Affected biotic resources include federally listed species such as the Cape Sable seaside sparrow, American crocodile, wood stork, and roseate spoonbill. The U.S. Geological Survey (USGS) is synthesizing scientific findings from hydrologic process studies, collecting data to characterize the ecosystem properties and functions, and integrating the results of these efforts into a research tool and management model for this Southern Inland and Coastal System(SICS). Scientists from all four disciplinary divisions of the USGS, Biological Resources, Geology, National Mapping, and Water Resources are contributing to this interdisciplinary project.

Florida↗
USGS1967

The Amazon, measuring a mighty river

The Amazon, the world's largest river, discharges enough water into the sea each day to provide fresh water to the City of New York for over 9 years. Its flow accounts for about 15 percent of all the fresh water discharged into the oceans by all the rivers of the world. By comparison, the Amazon's flow is over 4 times that of the Congo River, the world's second largest river. And it is 10 times that of the Mississippi, the largest river on the North American Continent.

Amazon River↗
USGS2011

Improved earthquake monitoring in the central and eastern United States in support of seismic assessments for critical facilities

Evaluation of seismic monitoring capabilities in the central and eastern United States for critical facilities - including nuclear powerplants - focused on specific improvements to understand better the seismic hazards in the region. The report is not an assessment of seismic safety at nuclear plants. To accomplish the evaluation and to provide suggestions for improvements using funding from the American Recovery and Reinvestment Act of 2009, the U.S. Geological Survey examined addition of new strong-motion seismic stations in areas of seismic activity and addition of new seismic stations near nuclear power-plant locations, along with integration of data from the Transportable Array of some 400 mobile seismic stations. Some 38 and 68 stations, respectively, were suggested for addition in active seismic zones and near-power-plant locations. Expansion of databases for strong-motion and other earthquake source-characterization data also was evaluated. Recognizing pragmatic limitations of station deployment, augmentation of existing deployments provides improvements in source characterization by quantification of near-source attenuation in regions where larger earthquakes are expected. That augmentation also supports systematic data collection from existing networks. The report further utilizes the application of modeling procedures and processing algorithms, with the additional stations and the improved seismic databases, to leverage the capabilities of existing and expanded seismic arrays.

Open-File Report↗
USGS2015

Digital geospatial presentation of geoelectrical and geotechnical data for the lower American River and flood plain, east Sacramento, California

To characterize the extent and thickness of lithologic units that may have differing scour potential, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, has performed several geoelectrical surveys of the lower American River channel and flood plain between Cal Expo and the Rio Americano High School in east Sacramento, California. Additional geotechnical data have been collected by the U.S. Army Corps of Engineers and its contractors. Data resulting from these surveys have been compiled into similar database formats and converted to uniform geospatial datums and projections. These data have been visualized in a digital three-dimensional framework project that can be viewed using freely available software. These data facilitate a comprehensive analysis of the resistivity structure underlying the lower American River corridor and assist in levee system management.

California↗
USGS1980

Holocene Pacific–North American plate interaction in southern Alaska: Implications for the Yakataga seismic gap

The St. Elias, Alaska, earthquake (magnitude 7.1 M s ) on February 28, 1979, occurred along the complex Pacific–North American plate boundary between Yakutat Bay and Prince William Sound, rupturing only a fraction of the seismic gap identified in that region. To aid in evaluating the potential for, and likely site of, a future earthquake occurring in the remainder of the gap, we have formulated a kinematic model of neotectonic deformation in southern Alaska from available geologic and seismic data. In this model the part of the North American plate bordering on the Gulf of Alaska is divided into three subblocks, which are partially coupled to the Pacific plate. On the basis of the model, the gap-filling rupture or ruptures would most likely be along the north-dipping thrust faults of the Pamplona zone between Icy Bay and the eastern end of the Aleutian Trench. If the accumulated strain of 3.8 m postulated for this region were released suddenly in one event involving the remainder of the gap, the result would be an earthquake as large as magnitude 8.

Geology↗
USGS1991

Pliocene-climate history of the western United States derived from lacustrine ostracodes

Pliocene sediments from several sites in western North America contain ostracodes indicating deposition in lacustrine and wetland settings. The ostracodes offer a means of reconstructing the aquatic paleoenvironment. Because water temperature, chemistry, and lake volume are coupled to climate, reconstruction of these parameters provides a direct insight into Pliocene climate. The site ages were determined from tephrochronology, paleomagnetics, and associated mammals. The morphology of many ostracode species also provides direct information about the paleoenvironment in which they lived. During the Pliocene (about 3.5-2.5 Ma) some species have unusually ornate carapace morphology indicative of large geologically stable lakes, which must have required a stable climate to sustain them. North American Pliocene climate changed from a modern-like state 4.5-3.5 Ma to a period with greater precipitation and less evaporation than today, 3.5-2.5 Ma. This wetter period, inferred from the large geologically long-lived lakes, implies a stable atmospheric circulation pattern. The stable circulation pattern collapsed around 2.5 Ma and climate returned to a modern-like situation.

western United States↗
USGS2013

History and evaluation of national-scale geochemical data sets for the United States

Six national-scale, or near national-scale, geochemical data sets for soils or stream sediments exist for the United States. The earliest of these, here termed the ‘Shacklette’ data set, was generated by a U.S. Geological Survey (USGS) project conducted from 1961 to 1975. This project used soil collected from a depth of about 20 cm as the sampling medium at 1323 sites throughout the conterminous U.S. The National Uranium Resource Evaluation Hydrogeochemical and Stream Sediment Reconnaissance (NURE-HSSR) Program of the U.S. Department of Energy was conducted from 1975 to 1984 and collected either stream sediments, lake sediments, or soils at more than 378,000 sites in both the conterminous U.S. and Alaska. The sampled area represented about 65% of the nation. The Natural Resources Conservation Service (NRCS), from 1978 to 1982, collected samples from multiple soil horizons at sites within the major crop-growing regions of the conterminous U.S. This data set contains analyses of more than 3000 samples. The National Geochemical Survey, a USGS project conducted from 1997 to 2009, used a subset of the NURE-HSSR archival samples as its starting point and then collected primarily stream sediments, with occasional soils, in the parts of the U.S. not covered by the NURE-HSSR Program. This data set contains chemical analyses for more than 70,000 samples. The USGS, in collaboration with the Mexican Geological Survey and the Geological Survey of Canada, initiated soil sampling for the North American Soil Geochemical Landscapes Project in 2007. Sampling of three horizons or depths at more than 4800 sites in the U.S. was completed in 2010, and chemical analyses are currently ongoing. The NRCS initiated a project in the 1990s to analyze the various soil horizons from selected pedons throughout the U.S. This data set currently contains data from more than 1400 sites. This paper (1) discusses each data set in terms of its purpose, sample collection protocols, and analytical methods; and (2) evaluates each data set in terms of its appropriateness as a national-scale geochemical database and its usefulness for national-scale geochemical mapping.

Conterminous United States↗
USGS2014

Digital topographic data based on lidar survey of Mount Shasta Volcano, California, July-September 2010

The most voluminous of the Cascade volcanoes, northern California’s Mount Shasta, is a massive compound stratovolcano composed of at least four main edifices constructed over a period of at least 590,000 years. An ancestral Shasta volcano was destroyed by Earth’s largest known Quaternary subaerial debris avalanche, which filled Shasta Valley, northwest of the volcano. The Hotlum cone, forming the present summit, the Shastina lava dome complex, and the Black Butte lava dome on the southwest flank, were constructed during the early Holocene. As part of the American Recovery and Reinvestment Act (ARRA) of 2009, the U.S. Geological Survey was awarded funding for high-precision airborne lidar (light detection and ranging) data collection at several volcanoes in the Cascade Range. Data collection was arranged by the Oregon Lidar Consortium, administered by the Oregon Department of Geology and Mineral Industries (DOGAMI). The Oregon Lidar Consortium contracted with Watershed Sciences, Inc., to collect 1,220 square km of high-precision airborne lidar data. These data provide a digital map of the ground surface beneath forest cover with horizontal resolution of 1 m (average of 1.82 ground laser returns per square meter) and estimated vertical accuracy of ±4 centimeters (1 sigma), and horizontal accuracies of ±1.5 centimeters. These data will contribute to monitoring and description of natural hazards, the study of regional geology and volcanic landforms, and analysis of landscape modification during and after the next volcanic eruption at Mount Shasta. Survey Bounding Coordinates: West Bounding Coordinate: −122.438774 East Bounding Coordinate: −121.888382 North Bounding Coordinate: 41.564495 South Bounding Coordinate: 41.126339

California↗
USGS2001

Geologic Map of the Lavinia Planitia Quadrangle (V-55), Venus

Introduction The Lavinia Planitia quadrangle (V-55) is in the southern hemisphere of Venus and extends from 25 to 50 south latitude and from 330 to 360 longitude. It covers the central and northern part of Lavinia Planitia and parts of its margins. Lavinia Planitia consists of a centralized, deformed lowland flooded by volcanic deposits and surrounded by Dione Regio to the west (Keddie and Head, 1995), Alpha Regio tessera (Bindschadler and others, 1992a) and Eve Corona (Stofan and others, 1992) to the northeast, itself an extensive rift zone and coronae belt to the east and south (Baer and others, 1994; Magee and Head, 1995), Mylitta Fluctus to the south (Magee Roberts and others, 1992), and Helen Planitia to the southwest (Senske and others, 1991). In contrast to other areas on Venus, the Lavinia Planitia area is one of several large, relatively equidimensional lowlands (basins) and as such is an important region for the analysis of processes of basin formation and volcanic flooding. Before the Magellan mission, Lavinia Planitia was known on the basis of Pioneer-Venus altimetry to be a lowland area (Pettengill and others, 1980);. Arecibo radar images showed that Lavinia Plaitia was surrounded by several corona-like features and rift-like fractures parallel to the basin margin to the east and south (Senske and others, 1991; Campbell and others, 1990). Arecibo data further revealed that the interior contained complex patterns of deformational features in the form of belts and volcanic plains, and several regions along the margins were seen to be the sources of extensive outpourings of digitate lava flows into the interior (Senske and others, 1991; Campbell and others, 1990). Early Magellan results showed that the ridge belts are composed of complex structures of both extensional and contractional origin (Squyres and others, 1992; Solomon and others, 1992) and that the complex lava flows (fluctus) along the margins (Magee Roberts and others, 1992) emanated from a variety of sources ranging from volcanoes to coronae (Magee and Head, 1995; Keddie and Head, 1995). In addition, global analysis of the distribution of volcanic features revealed that Lavinia Planitia is an area deficient in the distribution of distinctive volcanic sources and corona-like features (Head and others, 1992; Crumpler and others, 1993). Lavinia Planitia gravity and geoid data show that the lowland is characterized by a -30 mGal gravity anomaly and a -10 m geoid anomaly, centered on eastern Lavinia (Bindschadler and others, 1992b; Konopliv and Sjogren, 1994). Indeed, the characteristics and configuration of Lavinia Planitia have been cited as evidence for the region being the site of large-scale mantle down welling (Bindschadler and others, 1992b). Thus, this region is a laboratory for the study of the formation of lowlands, the emplacement of volcanic plains, the formation of associated tectonic features, and their relation to mantle processes. These questions and issues are the basis for our geologic mapping analysis. In our analysis we have focused on the geologic mapping of the Lavinia Planitia quadrangle using traditional methods of geologic unit definition and characterization for the Earth (for example, American Commission on Stratigraphic Nomenclature, 1961) and planets (for example, Wilhelms, 1990) appropriately modified for radar data (Tanaka, 1994). We defined units and mapped key relations using the full resolution Magellan synthetic aperture radar (SAR) data (mosaiced full resolution basic image data records, C1-MIDR's, F-MIDR's, and F-Maps) and transferred these results to the base map compiled at a scale of 1:5 million. In addition to the SAR image data, we incorporated into our analyses digital versions of Magellan altimetry, emissivity, Fresnel reflectivity, and roughness data (root mean square, rms, slope). The background for our unit definition and characterization is described in Tanaka (1994), Basilevsky and Head (1995a, b)

IMAP↗
USGS2001

High resolution study of petroleum source rock variation, Lower Cretaceous (Hauterivian and Barremian) of Mikkelsen Bay, North Slope, Alaska

Open File Report 01-480 was designed as a large format poster for the Annual Meeting of the American Association of Petroleum Geologists and the Society for Sedimentary Geology in Denver Colorado in June 2001. It is reproduced here in digital format to make widely available some unique images of mudstones. The images include description, interpretation, and Rock-Eval data that resulted from a high-resolution study of petroleum source rock variation of the Lower Cretaceous succession of the Mobil-Phillips Mikkelsen Bay State #1 well on the North Slope of Alaska. Our mudstone samples with Rock-Eval data plus color images are significant because they come from one of the few continuously cored and complete intervals of the Lower Cretaceous succession on the North Slope. This succession, which is rarely preserved in outcrop and very rarely cored in the subsurface, is considered to include important petroleum source rocks that have not previously been described nor explained Another reason these images are unique is that the lithofacies variability within mudstone dominated successions is relatively poorly known in comparison with that observed in coarser clastic and carbonate successions. They are also among the first published scans of thin sections of mudstone, and are of excellent quality because the sections are well made, cut perpendicular to bedding, and unusually thin, 20 microns. For each of 15 samples, we show a thin section scan (cm scale) and an optical photomicrograph (mm scale) that illustrates the variability present. Several backscattered SEM images are also shown. Rock-Eval data for the samples can be compared with the textures and mineralogy present by correlating sample numbers and core depth.

Open-File Report↗
USGS1984

Movement and fate of creosote waste in ground water, Pensacola, Florida; U.S. Geological Survey toxic waste--ground-water contamination program

In 1983, the U.S. Geological Survey, Office of Hazardous Waste Hydrology, selected the former American Creosote Works site near Pensacola, Florida as a national research demonstration area. Seventy-nine years (1902-81) of seepage from unlined discharge impoundments had released creosote, diesel fuel, and pentachlorophenol (since 1950) wastes into the ground-water system. A cluster of from 2 to 5 wells constructed at different depths at 9 sites yielded water which revealed contamination 600 feet downgradient and to a depth of 100 feet below land surface near the site. The best cross-sectional representation of the contaminant plume was obtained from samples collected and analyzed for oxidation-reduction sensitive inorganic chemical constituents. Energy dispersive x-ray fluorescence detected recently formed iron carbonate in soil samples from highly reducing ground-water zones. Approximately eighty specific organic contaminants were isolated from ground-water samples by gas-chromotography/mass spectrometry. Column studies indicate the dimethyl phenols are not sorbed or degraded by the sand-and-gravel aquifer materials. Five of nineteen individual phenolic and related compounds are biodegradable based on anaerobic digestor experiments with ACW site bacterial populations. The potential impacts in the nearby Pensacola Bay biotic community are being evaluated. (USGS)

Open-File Report↗
USGS2011

Exploration case study using indicator minerals in till at the giant Pebble porphyry Cu-Au-Mo deposit, southwest Alaska, USA

The Pebble deposit in southwest Alaska (Fig. 1) contains one of the largest resources of copper and gold in the world. It includes a measured and indicated resource of 5,942 million tonnes (Mt) at 0.42% Cu, 0.35 g/t Au, and 250 ppm Mo (0.30% copper equivalent, CuEQ, cut off) and contains significant concentrations of Ag, Pd, and Re (Northern Dynasty Minerals 2011). The deposit remains open at depth. The Pebble West zone was discovered in 1989 by Cominco American. In 2005, Northern Dynasty Minerals Ltd. (NDM) discovered Pebble East, and in July 2007, NDM partnered with Anglo American to form the Pebble Limited Partnership (PLP). The U.S. Geological Survey began collaborative investigations with PLP in 2007 to identify techniques that will improve mineral exploration in covered terranes. The Pebble deposit is an ideal location for such a study because the deposit is undisturbed (except for drilling), is almost entirely concealed by post-mineral volcanic rocks and glacial deposits, and because its distribution is well constrained in the subsurface by PLP’s drill-hole geology and geochemistry. An exploration method developed by Averill (2007) that utilizes porphyry copper indicator minerals (PCIMR) in glacial till samples was applied at Pebble; samples were collected up- and down-ice (of former glaciers) from the deposit. The distribution of several PCIMs identifies the deposit, which suggests that PCIMs may be useful in exploration for other concealed porphyry deposits in the region. In this study, we compare the efficacy of PCIMs relative to that of pond and stream sediments also collected in the deposit area. The Pebble deposit is located 380 km southwest of Anchorage, in the Bristol Bay region of southwest Alaska. There is no road network and access to the study area is by helicopter. The deposit is situated in a broad glacially sculpted topographic low at the head of three drainages, Talarik Creek, North Fork Koktuli River, and the South Fork Koktuli River (Fig. 1). The study area is in a zone of discontinuous permafrost and is masked by lichen-rich tundra vegetation.

Alaska↗