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At least 1,567 records · Page 87Linked to original sources
USGS2003

Determining temperature and thermal properties for heat-based studies of surface-water ground-water interactions: Appendix A of Heat as a tool for studying the movement of ground water near streams (Cir1260)

Advances in electronics leading to improved sensor technologies, large-scale circuit integration, and attendant miniaturization have created new opportunities to use heat as a tracer of subsurface flow. Because nature provides abundant thermal forcing at the land surface, heat is particularly useful in studying stream-groundwater interactions. This appendix describes methods for obtaining the thermal data needed in heat-based investigations of shallow subsurface flow.

Report↗
USGS1994

Tonsteins and clay-rich layers in coal-bearing intervals of the Eocene Manning formation, east-central Texas

Six samples from clay-rich intervals in the coal-bearing upper part of the Eocene Manning Formation were analyzed by scanning-electron microscopy and energy-dispersive X-ray fluorescence to determine the origin of minerals in the samples. Two samples were from surface-mine exposures of the 3500 coal bed near Bryan, Texas, and the remaining samples were from an exposure of a correlative interval at the Lake Somerville spillway about 60 km (37 mi) southwest of Bryan. Preliminary data suggest that both a 2-cm-thick (0.75-in) claystone from the upper part of the 3500 bed and the upper part of an 11-cm-thick (4.25-in) mudstone from the floor of the lower coal bed at the spillway were derived from volcanic ash falls. Both clay layers identified as possible tonsteins are composed of kaolinite and accessory quartz, euhedral to subhedral zircon, feldspars, and Ca-Al phosphates (crandallite?). Both alkali and plagioclase feldspars are observed in the two samples, but K-feldspar predominates in the upper clay layer of the 3500 bed, and plagioclase, with accessory Ti-bearing biotite, predominates in the sample from the floor of the spillway. These compositional differences suggest two separate volcanic ash falls. The other sampled clay layers contain rounded to subrounded zircons and feldspars in a mixed-layer clay groundmass, which suggests detrital rather than ash-fall origins.

Texas↗
USGS2019

Encylopedia of Caves

For many people, a visit to a cave is a wondrous event directing our minds to ponder the mysteries presented by these unique places and inspiring questions: How old is the cave? What was the role of water in forming the cave and where did the water come from? How is the cave connected to the surface environment? These are intriguing questions to ask, and karst scientists use isotope geochemistry to help solve these mysteries. Isotopes are atoms of the same chemical element that have the same number of protons but vary in their number of neutrons. As a result of their atomic mass difference, isotopes of a single element may exhibit slightly different chemical behavior. Radioisotopes are unstable and the nucleus of a parent isotope will spontaneously break apart (decay), releasing energy and changing into another element (daughter product) by loss or gain of protons, neutrons, or electrons. Stable isotopes, as implied by the name, are stable and do not spontaneously decay. These two types of isotopes are used widely by scientists to understand ancient and modern karst systems. Generally, radioisotopes are used for absolute dating karst water, cave sediments, cave formations (speleothems), and other material preserved in caves (such as bones). Stable isotopes can provide information about relative ages of cave water and speleothems. An absolute age provides a numeric date—such as 100,000 years old—whereas a relative age provides information that something is older or younger than something else—such as cave art is younger than a speleothem found in the same cave. Stable isotopes are used to study ancient karst systems because isotopic signals of past climate (paleoclimate) and environmental conditions (paleoenvironment) are preserved in speleothems and sediments. Stable isotopes are also used to understand modern systems, primarily through studies that distinguish sources of karst water, cave air, or contaminants, mixing of those sources, and biologic or chemical reactions that process compounds, such as breakdown of contaminants or organic matter. The variation in mass among isotopes is small, and isotope abundances are measured as a ratio of a common isotope to its less common isotopic counterparts (stable isotopes) or the abundance of a parent compared to daughter isotope (radioisotopes). As an example, hydrogen (H) has three naturally occurring isotopes. Most H comprises one proton (1H), but the rarer stable isotope (called deuterium) comprises one proton and one neutron (2H), and the radioisotope (called tritium) comprises one proton and two neutrons (3H). Because scientists use the minute differences in isotopes to test hypotheses, a scientist must understand the accuracy, precision, and error of the available methods, the assumptions about the chemical conditions of interest, and the limitations of the isotopic method being used. Many isotopic studies employ multiple isotopic tracers to better leverage the strengths and offset the limitations of using a single isotope. This article focuses on isotopes used to study the geology and hydrology of caves, but much additional isotopic work has been used to characterize the biology of caves.

Book chapter↗
USGS2019

Lithologies, ages, and provenance of clasts in the Ordovician Fincastle Conglomerate, Botetourt County, Virginia, USA

The Fincastle Conglomerate is an Ordovician polymictic, poorly sorted, matrix- and clast-supported cobble to boulder-rich conglomerate located just north of Fincastle, Botetourt County, VA. At least nine other cobble and boulder conglomerates are located in a similar stratigraphic position from Virginia to Georgia west of the Blue Ridge structural front. All except the Fincastle are dominated (~80%) by carbonate clasts; Fincastle clasts are much more varied and siliceous and it is this clast diversity that provides increased value for provenance and related studies. We have used a multidisciplinary approach that involves conodont analysis, sandstone petrography, in-situ outcrop clast characterization, optical petrography, electron-beam petrography and chemical analysis, and X-ray diffraction to provide data on lithologies, ages, and provenance. The size, roundness, and lithology of 1,656 clasts (> 1 cm) were measured in the field. Although, the clast lithology varies among the studied localities, the average lithology is sandstone and siltstone 12 %, vein quartz 17 %, limestone 31 %, low-grade quartzite/metasandstone 31 %, chert 6 %, and others 3 %. Dolomite, igneous, or high-grademetamorphic rock clastswere not identified in field study or in detailed laboratory analysis.Dolomite rhombs and authigenic albite feldsparwere observed in some limestone clasts. Quantitative petrographic data for the Fincastle sandstone clasts indicate tectonic environments from passive margin to transitional continental uplift, but the conglomeratematrixmodes have considerably less feldspar and plot in the foreland basin tectonic environment region. Proto-, para-, and euconodonts were identified from clast and matrix, but are long-ranging fauna indicating middle Cambrian toMiddle or Late Ordovician ages; color alteration index (CAI) for euconodonts varied from 3 to 3.5. The occurrence of well-rounded clasts including limestone suggests a nearby, high-energy environment, and that transport was rapid enough to preserve limestone before deposition into a foreland basin. The lack of igneous or high-grade metamorphic rocks clasts suggests that the erosional level sampled by the Fincastle Conglomerate did not include the underlying Grenville basement of igneous or high-grade metamorphic rocks.

Virginia↗
USGS2002

Real-time kinematic surveying at the Osage-Skiatook Petroleum Environmental Research sites, Osage County, Oklahoma

Highly accurate survey-grade Global Positioning System (GPS) technology was used at the two Osage-Skiatook petroleum environmental research sites to document the locations of observation wells, geoprobe holes, and other sampling sites of 15 research scientists. Real-time kinematic (RTK) GPS was the method used, because it is stable, fast, and accurate. Initially three survey monuments were installed one at each research site and one at the U.S. Army Corps of Engineers headquarters for Skiatook Lake. The monument locations were established by static GPS surveys that occupied each of the sites for four hours. The data were submitted to the NOAA-National Geodetic Survey (NGS) Online Positioning User Service (OPUS) for processing. OPUS processes the data relative to three sites on the NGS continuously operating reference station network (CORS). CORS provides GPS carrier phase and code range measurements in support of three-dimensional positioning activities throughout the United States. OPUS enables positioning accuracies, both horizontally and vertically, that approach a few centimeters relative to the National Spatial Reference System and electronically mails the results to the sender. The usual turnaround time for a data set is 2-3 minutes, depending upon the file size. Static GPS surveys are highly accurate, but require post processing the data and longer occupation time. The RTK surveys require a GPS base station positioned over a known monument, a GPS rover, and a radio link between the base station and the rover. The radio link transmits the base station correction data to the rover. The rover combines the base station data with the rover GPS data to produce real-time coordinates. The rover must maintain lock on at least four of the same satellites that the base station is tracking. Each survey location is occupied for 3 minutes. Setup time at each location is less than a minute, if the rover maintains lock on the satellites and the radio link to the base station. Accuracy in the horizontal component is 1 centimeter (cm) plus 2 parts per million (ppm) times the baseline distance and in the vertical component is 2 cm plus 2 ppm times the baseline distance. The calculated accuracy for the initial static GPS surveys that occupied the survey monuments ranged from 1.2 to 1.4 cm for the horizontal component and 2.2 to 2.4 cm for the vertical component. Calculated accuracy for the RTK surveys at the research sites are about 2.2 to 2.4 cm for the horizontal component and 4.2 to 4.4 cm for the vertical component.

Oklahoma↗
USGS2020

Micrometer-scale characterization of solid mine waste aids in closure due diligence

Precious- and base-metal mining often occurs in deposits with high acid-generating potential, resulting in mine waste that contains metals in forms of varying bioavailability, and therefore toxicity. The solids that host these metals are often noncrystalline, nanometer to micrometer in size, or undetectable by readily available analytical techniques (e.g., X-ray diffraction). This analytical shortcoming can pose a challenge when attempting to characterize sources and natural attenuation of metals at a given site, which is a best practice to satisfy closure due diligence. Numerous case studies have shown that efforts to characterize mine waste at multiple scales, particularly the micrometer scale, often lead to a better understanding of metal distribution and potential contamination risks. This paper presents a case study that compares the use of both traditional and non-traditional techniques to identify and quantify metal hosts in sediments downstream of the abandoned mine waste piles at the Ely Copper Mine Superfund site in Vermont (USA). The contaminant present in the highest concentration in the sediments is copper, yet not all copper-bearing solids were detected with bulk X-ray diffraction (XRD). At the micrometer scale, a combination of synchrotron-based X-ray absorption spectroscopy (XAS) and an automated mineralogy (AM) system were used to identify the most abundant copper-bearing solids. Bulk XAS and AM also provided semi-quantitative abundances of these solids in the sediment. At the Ely Copper Mine, copper in stream sediments was found to be predominantly hosted in sulphide minerals downstream of a major mine waste pile, whereas upstream copper was predominantly hosted in secondary iron and manganese (oxyhydr)oxides. These copper-bearing hosts were consistent with the expected bioavailability of copper in the sediments based on laboratory toxicity tests with aquatic organisms. When the bulk of copper was present in sulphides, aquatic organisms experienced greater survival than when copper was mostly associated with secondary iron and manganese (oxyhydr)oxides. The information gained from probing the sediments at multiple scales can now be used to prioritize containment and remediation strategies. While synchrotron-based analytical techniques have proven to be invaluable in many studies of mine waste, access to these techniques is limited. In contrast, access to a scanning electron microscope that can perform AM is becoming more common, primarily for the application in mining design and mineral processing operations. More recently, the successful use of AM to characterize mine waste suggests that this technique can be equally as valuable for mine closure plans. The resolution of information obtained may go beyond what is required from a regulatory perspective, but given that the results have the potential to be more conclusive than many traditional techniques, this level of characterization may save time and money in the long run.

Vermont↗
USGS2021

Toward an effective global green economy: The Critical Minerals Mapping Initiative (CMMI)

Global population growth, economic development and the accelerating pace of technological innovation are driving increased demand for non-fuel mineral commodities that are vital for emerging and low-carbon technologies. Examples of such commodities include cobalt and graphite for rechargeable batteries, tellurium in thin-film solar photovoltaics and rare earth elements (REE) in permanent magnets, electronics and medical technologies. These commodities are known as critical elements and/or minerals (collectively referred to as critical minerals), with the term critical used to define not only their importance for new technologies, but also their demand and vulnerability to supply disruption. The demand for critical minerals is likely to continue to grow, but supply is not assured. Therefore, national strategies in Australia, Canada, United States and elsewhere (e.g. Europe: Wittenberg et al. 2021) are being developed to encourage exploration and production, including resolving the geological processes responsible for their enrichrichment into viable ore deposits. In 2019, Geoscience Australia (GA), the Geological Survey of Canada (GSC) and the United States Geological Survey (USGS) formed the Critical Minerals Mapping Initiative (CMMI) to undertake research to develop a better understanding of critical mineral resources in known deposits, determine the geological controls on critical mineral distribution for deposits currently producing by-products, and identify new sources of supply through mineral prospectivity mapping and resource assessment.

SGA News↗
USGS2020

U.S. Geological Survey (USGS) Water-Use Data and Research (WUDR) program overview and status as of October 22, 2020

The USGS Water-Use Data and Research Program (WUDR) is an appropriated program that began in Federal fiscal year 2015 and is authorized under the SECURE Water Act (Sec. 9508 (c)). WUDR provides financial assistance through cooperative agreements to State water resource agencies. The WUDR Program has two main goals: To improve the availability, quality, compatibility, and delivery of water-use data that are collected and/or estimated by States to support national water-use assessments; and To integrate the water-use data into USGS databases in electronic or machine-readable formats.

Newsletter↗
USGS2022

U.S. Geological Survey (USGS) Water-Use Data and Research (WUDR) program overview and status as of March 31, 2022

The USGS Water-Use Data and Research Program (WUDR) is an appropriated program and is authorized under the SECURE Water Act (Sec. 9508 (c)). WUDR provides financial assistance through cooperative agreements to State water resource agencies. The WUDR Program has two main goals: • To improve the availability, quality, compatibility, and delivery of water-use data that are collected and/or estimated by States to support national water-use assessments; and • To integrate the water-use data into USGS databases in electronic or machine-readable formats.

Newsletter↗
USGS2010

Performance of map symbol and label design with format and display resolution options through scale for the national map

Symbol and label design for U.S. topographic mapping using data from The National Map has been progressing, partly in support of research by Buttenfield and Stanislawski on hydrographic generalization, and is sponsored by CEGIS, the USGS Center of Excellence for Geospatial Information Science. The work also seeks to make the best use of GIS for map design that requires no hand-work to make custom adjustments for readable displays. Users of electronic topographic map products may use U.S. topographic maps in multiple media, so the robustness of the designs will be tested across varied landscape regimes and through scale. Maps from hydrographic subbasins in Missouri, West Virginia, Florida-Georgia, Colorado, Utah, Texas, and urban areas of Saint Louis, and Atlanta are evaluated at six scales from 1:24,000 to 1:1,000,000. Map segments for the evaluation are selected to cover a wide sampling of symbol combinations and labeling challenges. Maps are examined on-screen in ArcGIS (MXD) and as a PDF export on-screen. Onscreen views are examined at 96 ppi, common for Windows desktop computer screens, and 130 ppi, representing the higher resolution that laptop computer screens offer. The goal of the work is to systematically refine the map symbols and labels so the resulting map performs well in all of these forms through all scales.

Conference Paper↗
USGS1975

Data availability and the role of the Earth Resources Observation Systems Data Center

With the launch of LANDSAT-1 in July 1972, and the follow-on launch of LANDSAT-2 in January of this year, routine availability of satellite imagery and electronic data of the earth's resources has become a reality. Federal data centers provide LANDSAT data to resource managers and the general public. These data centers have to date provided almost 500,000 frames of LANDSAT data at a cost of more than $2,000,000. Data from the LANDSAT satellite program, along with data and information from the Skylab manned program, are available over any location to anyone for the cost of reproduction.

Conference Paper↗
USGS1974

Distribution of copper in biotite and biotite alteration products in intrusive rocks near two Arizona porphyry copper deposits

Biotite and its alteration products (primarily chlorite) from igneous rocks around the Ray and Esperanza (Esperanza-Sierrita) porphyry copper deposits, Arizona, were analyzed for copper by electron microprobe. The copper occurs in amounts >90 p/m (limit of detection) in most of the chlorites analyzed, is concentrated at the optical and chemical boundary of chlorite and biotite, and is not associated with sulfur. Most unaltered igneous and hydrothermal biotites analyzed contain <90 p/m Cu, and except for one sample, all copper that was detected can be explained as contamination by copper from chlorite grains. The paucity of detectable copper in igneous and hydrothermal biotite and its presence in daughter chlorite suggest that the positive association noted by some workers between the proximity of an ore deposit and the copper content of biotite might be partly the result: of increased amounts of chloritization of biotite near a deposit coupled with difficulty in physically cleaning the biotite separates. Additionally, previous speculations that (1) part of the copper in a deposit may come from altered biotite, and (2) copper in biotite indicates how copper behaves in a differentiating magma, are of doubtful value if based on data derived from analyses of bulk mineral separates.

Arizona↗
USGS1978

Discrimination of fluvial and eolian deposits by number-frequency analysis of sediments of sand through silt size from a point bar, Rio Puerco, New Mexico

Fluvial and eolian deposits are interbedded in ephemeral-stream, arid-region point bars in the channel of the Rio Puerco, west of Albuquerque, N. Mex. Number frequency distributions of grain size for both types of deposits were obtained using an electronic automatic image analyzer for a suite of 10 samples. The number-frequency results were superior to weight-frequency (sieve) results in discriminating between eolian units and fluvial units in a vertical point-bar sequence. The image-analysis technique also identified those fluvial deposits whose size distributions have been altered significantly by winds, as well as fluvial deposits that do not show a prominent eolian-process component.

New Mexico↗
USGS1976

Microprobe study of olivine chromitites of the Goodnews Bay ultramafic complex, Alaska, and the occurrence of platinum

Electron-microprobe analyses of the dunite and olivine chromitite of the ultramaflc complex at Goodnews Bay, Alaska, show that the chromite contains more ferrous and ferric iron than is found in chromite from alpine or stratiform complexes. The iron-magnesium distribution coefficients between chromite and olivine demonstrate that more ferrous iron is partitioned to the chromite in the Goodnews Bay complex than to the chromite in stratiform chromitite but that the distribution is similar to that for alpine chromitite. The high iron content of the chromite and olivine at Goodnews Bay and the general geology of the complex indicate that it is a concentric-type ultramaflc complex similar to the platinum-bearing concentric complexes of southeastern Alaska. A platinum-alloy inclusion in the chromite found in the ultramaflc section at Goodnews Bay demonstrates that the olivine chromitite is the source of at least some of the platinum.

Alaska↗
USGS2022

Special issue: Landsat update 50th anniversary

Landsat Updates are prepared periodically and distributed electronically to provide information about Landsat activities and related topics of interest. This update highlights some of the articles and media that the USGS has developed over the last few months as well as upcoming events.

Newsletter↗
USGS2004

An automated approach to mapping corn from Landsat imagery

Most land cover maps generated from Landsat imagery involve classification of a wide variety of land cover types, whereas some studies may only need spatial information on a single cover type. For example, we required a map of corn in order to estimate exposure to agricultural chemicals for an environmental epidemiology study. Traditional classification techniques, which require the collection and processing of costly ground reference data, were not feasible for our application because of the large number of images to be analyzed. We present a new method that has the potential to automate the classification of corn from Landsat satellite imagery, resulting in a more timely product for applications covering large geographical regions. Our approach uses readily available agricultural areal estimates to enable automation of the classification process resulting in a map identifying land cover as ‘highly likely corn,’ ‘likely corn’ or ‘unlikely corn.’ To demonstrate the feasibility of this approach, we produced a map consisting of the three corn likelihood classes using a Landsat image in south central Nebraska. Overall classification accuracy of the map was 92.2% when compared to ground reference data.

Computers and Electronics in Agriculture↗
USGS2006

A method for mapping corn using the US Geological Survey 1992 National Land Cover Dataset

Long-term exposure to elevated nitrate levels in community drinking water supplies has been associated with an elevated risk of several cancers including non-Hodgkin's lymphoma, colon cancer, and bladder cancer. To estimate human exposure to nitrate, specific crop type information is needed as fertilizer application rates vary widely by crop type. Corn requires the highest application of nitrogen fertilizer of crops grown in the Midwest US. We developed a method to refine the US Geological Survey National Land Cover Dataset (NLCD) (including map and original Landsat images) to distinguish corn from other crops. Overall average agreement between the resulting corn and other row crops class and ground reference data was 0.79 kappa coefficient with individual Landsat images ranging from 0.46 to 0.93 kappa. The highest accuracies occurred in Regions where corn was the single dominant crop (greater than 80.0%) and the crop vegetation conditions at the time of image acquisition were optimum for separation of corn from all other crops. Factors that resulted in lower accuracies included the accuracy of the NLCD map, accuracy of corn areal estimates, crop mixture, crop condition at the time of Landsat overpass, and Landsat scene anomalies.

Computers and Electronics in Agriculture↗