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USGS2010

Radionuclides, trace elements, and radium residence in phosphogypsum of Jordan

Voluminous stockpiles of phosphogypsum (PG) generated during the wet process production of phosphoric acid are stored at many sites around the world and pose problems for their safe storage, disposal, or utilization. A major concern is the elevated concentration of long-lived 226Ra (half-life = 1,600 years) inherited from the processed phosphate rock. Knowledge of the abundance and mode-of-occurrence of radium (Ra) in PG is critical for accurate prediction of Ra leachability and radon (Rn) emanation, and for prediction of radiation-exposure pathways to workers and to the public. The mean (??SD) of 226Ra concentrations in ten samples of Jordan PG is 601 ?? 98 Bq/kg, which falls near the midrange of values reported for PG samples collected worldwide. Jordan PG generally shows no analytically significant enrichment (< 10%) of 226Ra in the finer (< 53 ??m) grain size fraction. Phosphogypsum samples collected from two industrial sites with different sources of phosphate rock feedstock show consistent differences in concentration of 226Ra and rare earth elements, and also consistent trends of enrichment in these elements with increasing age of PG. Water-insoluble residues from Jordan PG constitute <10% of PG mass but contain 30-65% of the 226Ra. 226Ra correlates closely with Ba in the water-insoluble residues. Uniformly tiny (< 10 ??m) grains of barite (barium sulfate) observed with scanning electron microscopy have crystal morphologies that indicate their formation during the wet process. Barite is a well-documented and efficient scavenger of Ra from solution and is also very insoluble in water and mineral acids. Radium-bearing barite in PG influences the environmental mobility of radium and the radiation-exposure pathways near PG stockpiles. ?? 2010 US Government.

Environmental Geochemistry and Health↗

USGS2025

Extremophile hotspots linked to containerized industrial waste dumping in a deep-sea basin

Decaying barrels on the seafloor linked to DDT contamination have raised concerns about the public health implications of decades old industrial waste dumped off the coast of Los Angeles. To explore their contents, we collected sediment cores perpendicular to five deep-sea barrels. The concentration of DDT and its breakdown products were highly elevated relative to control sites yet did not vary with distance from the barrels, suggesting that they were not associated with the contamination. Sediment cores collected through white halos surrounding three barrels were enriched in calcite and had elevated pH. The associated microbial communities were low diversity and dominated by alkalophilic bacteria with metagenome-assembled genomes adapted to high pH. A solid concretion sampled between a white halo and barrel was composed of brucite, a magnesium hydroxide mineral that forms at high pH. Based on these findings, we postulate that leakage of containerized alkaline waste triggered the formation of mineral concretions that are slowly dissolving and raising the pH of the surrounding sediment pore water. This selects for taxa adapted to extreme alkalinity and drives the precipitation of “anthropogenic” carbonates forming white halos, which serve as a visual identifier of barrels that contained alkaline waste. Remarkably, containerized alkaline waste discarded >50 years ago represents a persistent pollutant creating localized mineral formations and microbial communities that resemble those observed at some hydrothermal systems. These formations were observed at one-third of the visually identified barrels in the San Pedro Basin and have unforeseen, long-term consequences for benthic communities in the region.

California↗

USGS1998

Geologic studies in Alaska by the U.S. Geological Survey, 1996

This collection of 12 papers continues the annual series of U.S. Geological Survey (USGS) reports on geologic investigations in Alaska. The annual volume presents results from new or ongoing studies in Alaska that are of interest to scientists in academia, industry, land and resource managers, and the general public. The Geological Studies in Alaska volume reports the results of studies that cover a broad spectrum of earth science topics from many parts of the state (fig. 1). The papers in this volume are organized under the topics Environment and Climate, Resources, and Geologic Framework, in order to reflect the objectives and scope of USGS programs that are currently active in Alaska. Environmental studies are the focus of two articles in this volume: One study addresses the relation between glaciers and aquatic habitat on the Kenai River and another study evaluates the geochemistry of water draining chromite deposits in Alaska. Two papers address mineral resources in southwestern Alaska including a geochemical study of the Fortyseven Creek prospect and a geological and geochemical study of the Stuyahok area. Eight geologic framework studies apply a variety of techniques to a wide range of subjects throughout Alaska, including biostratigraphy, geochemistry, geochronology, paleomagnetism, sedimentology, and tectonics. Two bibliographies at the end of the volume list reports about Alaska in USGS publications released in 1996 and reports about Alaska by USGS authors in non-USGS publications in 1996.

Alaska↗

USGS2025

Factors affecting the distribution of water-bearing fractures in the bedrock aquifers of West Virginia

Bedrock aquifers cover 23,601 square miles within the State of West Virginia and comprise 97.4 percent of the surficial area within the State; the remaining 2.6 percent (621 square miles) consists of alluvial sand-and-gravel and glacial outwash aquifers bordering the State’s major rivers. While West Virginia’s alluvial aquifers have been studied extensively, bedrock aquifers have only been characterized for studies completed in a few areas in Jefferson, McDowell, and Monroe Counties. Bedrock aquifers are water supplies for public supply, agriculture, industry, and residential homeowner use. In this study, the U.S. Geological Survey, in cooperation with the West Virginia Department of Environmental Protection Division of Water and Waste Management, provides a statewide assessment of the occurrence and distribution of fractures within bedrock aquifers of the State and the various topographic, physiographic, and lithologic influences controlling the occurrence and distribution of bedrock fractures. The results of this study provide an increased understanding of the distribution of fractures in bedrock aquifers in West Virginia and help to verify trends that have been suspected for many years but were never well documented or verified by data. The results confirmed that the density of fractures and those that were determined to be water bearing decrease significantly with depth. A statistically significant difference in the density of fractures was observed at a depth of 215 feet for wells in the Appalachian Plateaus Physiographic Province’s and in the Valley and Ridge Physiographic Province’s aquifers; a higher density of fractures and water-bearing fractures were above a depth of 215 feet than below that depth. This is an important consideration when drilling wells for residential, commercial, industrial, or agricultural water supply. Abandoned underground coal mines are commonly believed to form large pools of water in the interconnected mine entries in abandoned room and pillar coal mines. Such pools of water can and do exist in abandoned underground coal mines, but many mines lack open entries and are held up by overburden strata and pillars that can collapse and form aquifers comprised of vast interconnected rubble zones (gob), especially in older mines. Data assessed for this study showed that shale-corrected values of effective porosity for limestone aquifers in West Virginia had a median value of 2 percent and an average value of 4 percent and generally are mineralized with low effective porosity. Argillaceous or sandy limestone has a median shale-corrected porosity of 4 percent and an average shale-corrected porosity of 5 percent. The median and average shale-corrected porosity of sandstone aquifers was estimated to be 14 percent, but the median shale-corrected porosity for argillaceous or calcareous sandstone was 5 percent and the average shale-corrected porosity for argillaceous or calcareous sandstone was 6 percent. Even though shale has a relatively high total sonic porosity compared to other lithologies, shale and siltstone had relatively low shale-corrected porosity, ranging from 0 to 2 percent. Well yields were previously documented to be highest in valley settings, lowest on hilltops, and intermediate on hillsides. Transmissivity data provided by this study confirm this general pattern within the Appalachian Plateaus Province; however, the Valley and Ridge Province does not follow this pattern. While still lowest on hilltop settings, the highest well yields were in hillside settings. The trend for the Valley and Ridge Province was likely skewed because of 9 high-yield wells specifically targeting deeper thin limestone units, such as the Tonoloway and Helderberg Limestones, at depths with transmissivity in excess of 2,000 feet squared per day in Mineral County, West Virginia, or targeting karst aquifers in Berkeley, Jefferson, or Greenbrier Counties, West Virginia. Finally, water-bearing fractures have been hypothesized to comprise a small number of all fractures within a typical bedrock well in West Virginia. Data collected for this study support this theory. A total of 3,403 fractures were identified during this study; 3,151 (92.6 percent) of those fractures are low-transmissive, and only 252 (7.4 percent) fractures are water-bearing. Even though a well may contain many fractures, less than 8 percent are considered water-bearing fractures.

West Virginia↗

USGS2020

Energy and minerals division tight oil and gas committee: Activities and commodity report for 2019-2020

In 2019, total daily tight oil and gas production increased in the United States month over month, with annualized growth of 14% for oil and 12% for gas. Those gains leveled off in the first quarter of 2020 due to aggressive price competition and increases in international production. Then came the pandemic with a substantially larger dose of economic turmoil, driving down demand due in part to shelter in place orders and safety concerns around travel. Between March and May, tight oil and gas production dropped by nearly 2 million bpd and almost 5 Bcf/day before beginning to recover. Production has continued to increase for the most part through the second half of 2020, but drilling remains subdued throughout most of the U.S. and uncertainty around long term demand along with the current price environment and general state of the economy has contributed to layoffs throughout the industry. Some shale-gas production has declined recently, but a few areas have seen expansion due to construction of LNG facilities along the East Coast of the U.S. (e.g., the Haynesville Formation). Current U.S. shale-gas production is still higher now than in 2019, with daily production of almost 71 Bcf as of October 2020 driven in large part by increased production from the Marcellus Shale in the Appalachian Basin and shales within the Permian Basin. Shale liquids production is down by around a million bpd to approximately 7.1 million (September 2020; U.S. EIA) from pre-pandemic production levels at the end of 2019 and beginning of 2020. Tight oil production remains dominated by plays in the Permian Basin as well as the Bakken and Eagle Ford Formations. On the development and production front, new enhanced oil recovery approaches for tight shale reservoirs are being more widely implemented. Natural gas or CO2 injection is currently being utilized in the Bakken Formation, Eagle Ford Formation, Anadarko Basin, and the Permian Basin to optimize injection sequences and boost recovery. Refracturing of existing wells to reduce drilling costs, improve production, and prolong well productive life has also begun to occur more widely in developed plays. International interest in exploiting hydrocarbons from unconventional reservoirs continues to develop, with active exploration projects on most continents. Europe remains relatively underexplored as compared to North America, although a total of 141 exploration and appraisal wells with a possible shale-gas exploration component have been spudded, including horizontal legs from vertical wells. Shale exploration has made a breakthrough in China with shale gas output in 2019 of 10 billion cubic meters (35.3 Bcf), 60% of which was produced from Sinopec’s Fuling Shale Gas field. Lacustrine shale oil exploration has also been successful in the Sichuan and Ordos Basins in central China, Junggar and Tarim Basins in northwest China, and Songliao Basin in north China, and Bohai Bay Basins in northeast China as of 2018. South America’s potential as an unconventional shale gas and oil province is mainly in Argentina and Brazil, where the production from Neuquen Basin’s tight shale of the Vaca Muerta Formation has been steadily increasing since 2016, but only 4% of the shale resource has been developed thus far. According to International Energy Agency’s report in 2013, Brazil holds the 9th largest unconventional gas reserves. Brazil has shale oil and gas potential in the Parana, Solimoes and Amazon Basins and is actively producing from the oil shale unit of the Irati Formation. In 2019, the Brazil energy ministry launched REATE 2020 to boost onshore investments that include the expectation of drilling an experimental unconventional well in the northeast region. For this inaugural report, the new AAPG EMD Tight Oil and Gas Committee (TO&G; formerly the Shale Gas & Liquids and Tight Gas Sands committees) has developed new commodity report requirements for contributors. This includes shorter annual reports focused on new developments, play concepts, along with the typical updates on production and new drilling in the play areas they cover. We are also asking contributors to collect background geologic and production related information into a document that summarizes important features of the plays they cover that will be stored on the TO&G webpage along with our commodity reports. TO&G is currently working to expand the number of contributors to cover more play areas and replace committee and advisory board members that have recently stepped down. Changes to committee leadership occurred in October as recent chairs transition to EMD elected positions.

Activities and Commodities Report↗

USGS2019

Status of three-dimensional geological mapping and modeling activities in the U.S. Geological Survey

The U.S. Geological Survey (USGS), created in 1879, is the national geological survey for the United States and the sole science agency within its cabinet-level bureau, the Department of the Interior. The USGS has a broad mission, including: serving the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect quality of life. USGS scientific activities are organized around major topics, or Mission Areas, aligned with distinct science themes; three-dimensional (3-D) modelling typically supports research and project work within a specific Mission Area. The vastness, diversity, and complexity of the geological landscape of the United States has resulted in the creation of 3-D geological framework models that are local or regional in scale; a National-scale 3-D model is only beginning to evolve. This paper summarizes 3-D geological modeling at the USGS and does not discuss 3-D modeling that is conducted by other Federal agencies, state geological surveys, academia, or industry within the U.S. This paper updates and expands upon a similar status report of USGS 3-D modeling activities of Jacobsen et al. (2011).

Report↗

USGS2004

Mineral commodity profiles: Cadmium

Overview -- Cadmium is a soft, low-melting-point metal that has many uses. It is similar in abundance to antimony and bismuth and is the 63d element in order of crustal abundance. Cadmium is associated in nature with zinc (and, less closely, with lead and copper) and is extracted mainly as a byproduct of the mining and processing of zinc. In 2000, it was refined in 27 countries, of which the 8 largest accounted for two-thirds of world production. The United States was the third largest refiner after Japan and China. World production in 2000 was 19,700 metric tons (t) and U.S. production was 1,890 t. In the United States, one company in Illinois and another in Tennessee refined primary cadmium. A Pennsylvania company recovered cadmium from scrap, mainly spent nickel-cadmium (NiCd) batteries. The supply of cadmium in the world and in the United States appears to be adequate to meet future industrial needs; the United States has about 23 percent of the world reserve base.

Open-File Report↗

USGS1995

Structure of the basins and ranges, Southwest New Mexico, an interpretation of seismic velocity sections

This report presents a geologic appraisal of seismic velocity sections that profile a total of 790 km in southwest New Mexico west of Las Cruces and south of Lordsburg and Deming. The present work outlines the contribution of these velocity sections to estimating areas favorable for mineral resource occurrences. Seismic refraction surveys are carried out with the initial goal of estimating the subsurface distribution of acoustic compressional velocity (Vp), which may ultimately be interpreted to provide information on lithology, geologic structure, and the occurrence of natural resources. The seismic sections presented here show velocity detail having dimensions of 100's to 1000's of meters to a depth of about 2.5 km, and across a net of traverses that profile most basins well as several ranges in the study area. Figure 1 shows the location of the seismic refraction lines. The lines are designated 1, 2, 3, 4, 5, and 7; there is no line 6. The survey covers a broad swath of the southwest Basin and Range Province extending from the Arizona border eastward to the Rio Grande River, and from the Mexican border to about lat. 32° 30' N. Lines 1, 3, and 7 traverse the axis of basins in roughly northsouth directions; the remaining lines 2, 4, and 5 trend east-west and cross various ranges and basins. Seismic data that have been collected in this region include deep-crustal refraction traverses by university scientists and commercial seismic reflection profiles acquired for petroleum exploration. Results of deep-crustal refraction studies are reviewed to provide a regional setting for the higher resolution refraction data. Results from seismic reflection will not be discussed. Industry reflection data in the area are not generally available for non-proprietary use. The nearest reflection data publicly available are in the Socorro area, about 80 km north of the present study area (Brown and others, 1980). These data were acquired by the Consortium for Continental Reflection Profiling (COCORP), a public-supported research group, to investigate the possibility of magma beneath part of the Rio Grande valley. Up to 1978 there were about 36 deep borings in the region of southwest New Mexico (Thompson and others, 1978). This drilling resulted mainly from an evaluation of petroleum potential of the Pedrogosa basin which is an extensive area of Paleozoic subsidence in Arizona, New Mexico, and Mexico that accumulated about three kilometers of Paleozoic sedimentary rock (Zeller, 1965; Thompson and others, 1978). Of these drill holes, 25 are close enough to the present seismic sections to provide correlations of velocity to lithology, and to provide an estimate of the errors associated with depth-to-interface interpretations. This information is summarized prior to considering the implications of the seismic sections in detail. The major portion of the report centers around two plates: Plate I shows seismic lines and selected drill hole locations superimposed on gravity contours, and Plate II shows velocitysections with drill hole summaries. These plates provide the foundation for developing inferences on buried lithologic, structural, and mineral resources for the region.

New Mexico↗

USGS2006

Drivers of U.S. mineral demand

Introduction: The word 'demand' has different meanings for different people. To some, it means their 'wants and needs,' to others it is what they consume. Yet, when considering economics, demand refers to the specific amounts of goods or services that individuals will purchase at various prices. Demand is measured over a given time period. It is determined by a number of factors including income, tastes, and the price of complementary and substitute goods. In this paper, the term consumption is used fairly synonymously with the term demand. Most mineral commodities, like iron ore, copper, zinc, and gravel, are intermediate goods, which means that they are used in the production of other goods, called final goods. Demand for intermediate goods is called derived demand because such demand is derived from the demand for final goods. When demand increases for a commodity, generally the price rises. With everything else held constant, this increases the profits for those who provide this commodity. Normally, this would increase profits of existing producers and attract new producers to the market. When demand for a commodity decreases, generally the price falls. Normally, this would cause profits to fall and, as a consequence, the least efficient firms may be forced from the industry. Demand changes for specific materials as final goods or production techniques are reengineered while maintaining or improving product performance, for example, the use of aluminum in the place of copper in long distance electrical transmission lines or plastic replacing steel in automobile bumpers. Substitution contributes to efficient material usage by utilizing cheaper or technically superior materials. In this way, it may also alleviate materials scarcity. If a material becomes relatively scarce (and thus more expensive), a more abundant (and less expensive) material generally replaces it (Wagner and others, 2003, p. 91).

Open-File Report↗

USGS2011

Guidance manual for forensic analysis of perchlorate in groundwater using chlorine and oxygen isotopic analyses

Increased health concerns about perchlorate (ClO4-) during the past decade and subsequent regulatory considerations have generated appreciable interest in source identification. The key objective of the isotopic techniques described in this guidance manual is to provide evidence concerning the origin of ClO4- in soils and groundwater and, more specifically, whether that ClO4- is synthetic or natural. Chlorine and oxygen isotopic analyses of ClO4- provide the primary direct approach whereby different sources of ClO4- can be distinguished from each other. These techniques measure the relative abundances of the stable isotopes of chlorine (37Cl and 35Cl) and oxygen (18O, 17O, and 16O) in ClO4- using isotope-ratio mass spectrometry (IRMS). In addition, the relative abundance of the radioactive chlorine isotope 36Cl is measured using accelerator mass spectrometry (AMS). Taken together, these measurements provide four independent quantities that can be used to distinguish natural and synthetic ClO4- sources, to discriminate different types of natural ClO4-, and to detect ClO4- biodegradation in the environment. Other isotopic, chemical, and geochemical techniques that can be applied in conjunction with isotopic analyses of ClO4- to provide supporting data in forensic studies are also described. This guidance manual is intended to provide details of the methodology used to (1) collect ClO4- samples from the environment, particularly from groundwater, which is the main medium of interest for ClO4- source identification; (2) purify the collected ClO4- samples; (3) conduct oxygen (O) and chlorine (Cl) isotopic analyses on the purified samples; and (4) determine probable sources using the resulting isotope data. Current practices for groundwater sampling and quality assurance for sample collection, purification, and measurement of Cl and O isotopes in ClO4- are provided. A detailed case study of source evaluation in groundwater on Long Island is given along with the current literature on the subject of ClO4- source discrimination. ClO4- in the environment is derived from both synthetic and natural sources. Synthetic ClO4- salts, including ammonium perchlorate (NH4ClO4) and potassium perchlorate (KClO4), have been widely used as oxidants by the military and aerospace industry. A variety of commercial products also contain synthetic ClO4-,including fireworks, matches, air bags, chlorine bleach, safety flares, perchloric acid, and chlorate herbicides. Historical disposal practices by the military, aerospace industry, and chemical manufacturers have resulted in groundwater and drinking water contamination with ClO4- in the United States. Isolated contamination from fireworks, road flares, explosives, and perchloric acid has also been reported. However, ClO4- is also a naturally occurring anion. It is present with sodium nitrate (NaNO3) in surficial deposits in the Atacama Desert of Chile at an average concentration of around 0.1% (by mass) of the total soluble salt, and these deposits (sometimes referred to as “Chilean caliche”) were widely used in the United States during the first half of the 20th century as a source of inorganic nitrogen fertilizer. Natural ClO4- that is not associated with Chilean fertilizers has also recently been detected in the vadose zone, groundwaters, and mineral deposits collected from the arid southwestern United States, including 155,000 km2 of groundwater in the Southern High Plains (SHP) of Texas and New Mexico. In addition to synthetic sources, natural ClO4- from both Chilean fertilizers and indigenous sources represents a potentially large source of ClO4- in groundwater and drinking water in the United States.

Report↗

USGS1979

A geohydrologic overview for the Pecora Symposium field trip, June 1979

The settlement and development of South Dakota has been closely related to both its mineral and water resources In 1874 the discovery of gold in the Black Hills led to the opening and development of the area west of the Missouri River. Towns and farms both here and east of the Missouri were located near dependable water supplies which the settlers learned were not as plentiful as in the more humid areas in the east. Although there is still much dry-land farming and cattle raising throughout the State, the expansion of agriculture has depended heavily on the development of controlled water supplies. Water from flowing artesian wells was extremely important to early settlers and developers. Today, thousands of these wells still supply an important part of the water on which South Dakota's agricultural, tourist, and industrial economy thrive.

South Dakota↗

USGS2025

Modeling interconnected minerals markets with multicommodity supply curves: Examining the copper-cobalt-nickel system

Demand for many of the metals used in the energy transition is expected to grow rapidly. Many of these are by-products, often considered critical because their production responds weakly to prices and is instead tied to the economics of the host mineral. We present a model of prices and production for jointly produced commodities that accounts for interconnectivity between host and by-product markets at the mine level. We demonstrate this method using the copper–cobalt–nickel system, in which approximately 99% of cobalt is a by-product of copper or nickel mining. Our results show that the model more accurately captures the economic benefits of diversified mine outputs than previous approaches. Furthermore, changes in demand drivers for any two commodities produce non-linear effects on production and price. We challenge the prior best-practice assumption that cobalt cannot impact the copper or nickel markets. Recognizing the importance of both copper and cobalt for future electrification, we emphasize that incentivizing the copper industry to reduce cobalt supply risks could inadvertently undermine copper supply.

Nature Communications↗

USGS2012

Deepwater Program: Studies of Gulf of Mexico lower continental slope communities related to chemosynthetic and hard substrate habitats

This report summarizes research funded by the U.S. Geological Survey (USGS) in collaboration with the University of North Carolina at Wilmington (UNCW) on the ecology of deep chemosynthetic communities in the Gulf of Mexico. The research was conducted at the request of the U.S. Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE; formerly Minerals Management Service) to complement a BOEMRE-funded project titled "Deepwater Program: Investigations of Chemosynthetic Communities on the Lower Continental Slope of the Gulf of Mexico." The overall research partnership, known as "Chemo III," was initiated to increase understanding of the distribution, structure, function, and vulnerabilities of these poorly known associations of animals and microbes for water depths greater than 1,000 meters (m) in the Gulf of Mexico. Chemosynthetic communities rely on carbon sources that are largely independent of sunlight and photosynthetic food webs. Despite recent research directed toward chemosynthetic and deep coral (for example, Lophelia pertusa) based ecosystems, these habitats are still poorly studied, especially at depths greater than 1,000 m. With the progression into deeper waters by fishing and energy industries, developing sufficient knowledge to manage these deep ecosystems is essential. Increased understanding of deep-sea communities will enable sound evaluations of potential impacts and appropriate mitigations.

Gulf Of Mexico↗

USGS2008

Inventory and review of existing PRISM hydrogeologic data for the Islamic Republic of Mauritania, Africa

The USGS entered into an agreement with the Mauritania Ministry of Mines and Industry to inventory and review the quality of information collected as part of the Project for Strengthening of the Institutions in the Mining Sector (PRISM). Whereas the PRISM program collected geophysical, geochemical, geological, satellite, and hydrogeologic information, this report focuses on an inventory and review of available hydrogeologic data provided to the USGS in multiple folders, files, and formats. Most of the information pertained to the hydrogeologic setting and the water budget of evaporation, evapotranspiration, and precipitation in the Choum-Zouerate area in northwestern Mauritania, and the country of Mauritania itself. Other information about the quantity and quality of groundwater was found in the relational Access database. In its present form, the limited hydrogeologic information was not amenable to conducting water balance, geostatistical, and localized numerical modeling studies in support of mineral exploration and development. Suggestions are provided to remedy many of the data's shortcomings, such as performing quality assurance on all SIPPE2 data tables and sending questionnaires to appropriate agencies, mining and other companies to populate the database with additional meteorology, hydrology, and groundwater data.

Open-File Report↗

USGS2012

Alluvial diamond resource potential and production capacity assessment of Guinea

In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. The goal of this study was to estimate the alluvial diamond resource endowment and the current production capacity of the alluvial diamond mining sector of Guinea. A modified volume and grade methodology was used to estimate the remaining diamond reserves within Guinea's diamondiferous regions, while the diamond-production capacity of these zones was estimated by inputting the number of artisanal miners, the number of days artisans work per year, and the average grade of the deposits into a formulaic expression. Guinea's resource potential was estimated to be approximately 40 million carats, while the production capacity was estimated to lie within a range of 480,000 to 720,000 carats per year. While preliminary results have been produced by integrating historical documents, five fieldwork campaigns, and remote sensing and GIS analysis, significant data gaps remain. The artisanal mining sector is dynamic and is affected by a variety of internal and external factors. Estimates of the number of artisans and deposit variables, such as grade, vary from site to site and from zone to zone. This report has been developed on the basis of the most detailed information available at this time. However, continued fieldwork and evaluation of artisanally mined deposits would increase the accuracy of the results.

Scientific Investigations Report↗

USGS2015

Indium: bringing liquid-crystal displays into focus

Introduction Indium is rare in the Earth’s crust. The continental crust contains an average of about 50 parts per billion of indium, whereas the oceanic crust contains about 72 parts per billion, which is similar to meteoritic abundances and comparable to the crustal abundance of silver. Indium minerals are rare in nature and only 12 indium minerals are known. In its elemental form, indium is a soft, lustrous, silver-white metal with a low melting point relative to other metals. It is ductile and malleable, even at temperatures approaching absolute zero, making it ideal for cryogenic applications. Indium was discovered in the mid-1800s by two German chemists who were investigating zinc ores from Freiberg, Saxony. They named it after the distinctive indigo-blue color observed in its emission spectrum. For years indium remained only a scientific curiosity and early applications of indium were few, but included manufacturing of light-emitting diodes and coatings for bearings used in aircraft engines. Indium-bearing nuclear control rods became more widely used in the 1970s, and today the major application of indium is in manufacturing liquid-crystal displays. Compared to more abundant industrial metals such as lead and zinc, information about the behavior and toxicity of indium in the environment is limited. However, many indium compounds have been proven to be toxic to animals.

Fact Sheet↗

USGS2008

Scientific objectives of the Gulf of Mexico gas hydrate JIP leg II drilling

The Gulf of Mexico Methane Hydrate Joint Industry Project (JIP) has been performing research on marine gas hydrates since 2001 and is sponsored by both the JIP members and the U.S. Department of Energy. In 2005, the JIP drilled the Atwater Valley and Keathley Canyon exploration blocks in the Gulf of Mexico to acquire downhole logs and recover cores in silt- and clay-dominated sediments interpreted to contain gas hydrate based on analysis of existing 3-D seismic data prior to drilling. The new 2007-2009 phase of logging and coring, which is described in this paper, will concentrate on gas hydrate-bearing sands in the Alaminos Canyon, Green Canyon, and Walker Ridge protraction areas. Locations were selected to target higher permeability, coarser-grained lithologies (e.g., sands) that have the potential for hosting high saturations of gas hydrate and to assist the U.S. Minerals Management Service with its assessment of gas hydrate resources in the Gulf of Mexico. This paper discusses the scientific objectives for drilling during the upcoming campaign and presents the results from analyzing existing seismic and well log data as part of the site selection process. Alaminos Canyon 818 has the most complete data set of the selected blocks, with both seismic data and comprehensive downhole log data consistent with the occurrence of gas hydrate-bearing sands. Preliminary analyses suggest that the Frio sandstone just above the base of the gas hydrate stability zone may have up to 80% of the available sediment pore space occupied by gas hydrate. The proposed sites in the Green Canyon and Walker Ridge areas are also interpreted to have gas hydrate-bearing sands near the base of the gas hydrate stability zone, but the choice of specific drill sites is not yet complete. The Green Canyon site coincides with a 4-way closure within a Pleistocene sand unit in an area of strong gas flux just south of the Sigsbee Escarpment. The Walker Ridge site is characterized by a sand-prone sedimentary section that rises stratigraphically across the base of the gas hydrate stability zone and that has seismic indicators of gas hydrate.

Conference Paper↗

USGS1967

Geology and petrology of the Greenville quadrangle, Piscataquis and Somerset Counties, Maine

In the Greenville quadrangle, west-central Maine, slate, siltstone, and sandstone (calcareous and noncalcareous) of probable Silurian to Early Devonian age are intruded by a large mafic pluton and two granitic stocks of probable Early Devonian age. Ages of the sedimentary rocks are based upon tentative correlations with fossiliferous beds in adjacent quadrangles because the few fossils in the Greenville quadrangle are nondiagnostic; ages of the intrusive rocks are based upon radiometric age determinations. The sedimentary rocks are tightly folded about northeast-trending axes and have strong slaty cleavage. Widespread graded bedding is very useful in determining the tops of beds and thus the location of fold axes. The sedimentary rocks are in the chlorite zone of metamorphism except in the contact aureoles where the metamorphism ranges from the biotite zone, through the andalusiite-amphibole zone, to the sillimanite-cordierite zone adjacent to the intrusions; retrograde metamorphism is a minor local feature. The mafic rocks are part of the Moxie pluton, which extends southwest and northeast of the Greenville quadrangle for a total distance of about 45 miles. Troctolite and norite are the principal rock types; gabbro is less common. Plagioclase is the dominant mineral; it usually makes up 50-75 percent of the rock. Olivine and orthopyroxene are widespread, clinopyroxene is uncommon and biotite and hornblende are generally present in small amounts. The rocks can be separated into magnesium-rich and iron-rich varieties; magnesium-rich olivine and orthopyroxene are usually accompanied by plagioclase containing from 57 to 77 percent anorthite, and iron-rich olivine and orthopyroxene are associated with plagioclase containing about 50-62 percent anorithite. Compositional layering is rare, but flow structure is very common. Flow structure generally dips northward to eastward, whereas geophysical data indicate that the contacts of the pluton dip southeastward. The granitic stocks are discordant pipelike bodies that range from granodiorite to quartz monzonite in composition. Both the mafic and the felsic intrusions are undeformed and unmetamorphosed. Slate quarrying was once an important industry in the region, but in 1965 only one quarry was active at Monson just east of the report area. Slate is a potential source of raw material for lightweight concrete aggregate. There are several possible sites for stone quarries in the intrusive masses. Sand and gravel resources seem to be limited. Small amounts of sulfides that have low copper and nickel values are known at a few places in the mafic pluton.

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