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USGS1996

U.S. Geological Survey programs in Texas

The U.S. Geological Survey (USGS) is the Federal Government's primary source of data on the quantity and quality of the Nation's water resources, its principal civilian map making agency, and its primary provider of information on natural hazards and mineral, energy, and biological resources. The USGS makes unbiased scientific information available equally to all interested parties. Most USGS work in Texas involves the appraisal of the State's water resources in cooperation with more than 80 local, State, and Federal agencies. The foundation of a wide range of hydrologic data-collection and interpretive programs is the stream-gaging program. The Texas network of streamflow-gaging stations, which provides water data for water-resources planning and design, hydrologic research, and operation of water-resources projects, is part of a nationwide aggregation of networks that is unique because of nationally consistent, prescribed standards by which the data are collected and processed. The USGS continues to expand collection of data for paper and digital maps. The best-known products of the USGS in Texas are its 1:24,000-scale topographic maps. These maps depict basic natural and cultural features of the landscape. Maps at this scale (1 inch on the map represents 2,000 feet on the ground) are useful for civil engineering, land-use planning, and natural-resource monitoring, and have long been favorites with the general public for a wide variety of outdoor uses. The USGS also continues to monitor geologic conditions in Texas associated with rare but potentially dangerous earthquakes. Recently, the Nation Biological Service (now the Biological Resources Division) joined the USGS to continue their appraisal of the nation's biological resources.

Fact Sheet↗

USGS2004

Analysis of MASTER thermal data in the Greeley area of the Front Range Urban Corridor, Colorado — Delineation of sites for infrastructure resource characterization

Sand and soils southwest of Greeley, Colorado, were characterized for mineral composition and industrial quality. Radi-ance data from the thermal channels of the MASTER simulator were calibrated using estimated atmospheric parameters. Chan-nel emissivities were approximated using an estimated ground temperature. Subsequently, a decorrelation algorithm was used to calculate inverse wave emissivity images. Six soil classes, one vegetation class, water, and several small classes were defined using an unsupervised classification algorithm. Ground covered by each of the derived emissivity spectral classes was studied using color-infrared air photos, color-infrared composite MAS-TER data, geologic maps, NASA/JPL Airborne Visible and Infra-red Imaging Spectrometer (AVIRIS) data, and field examination. Spectral classes were characterized by their responses and related to their mineral content through field examination. Classes with a minimum at channel 44, and having a similar spectral shape to quartz, field checked as containing abundant quartz. Classes with a minimum at channel 45, and having a spectral shape similar to the sheet minerals, were found in the field to contain abundant mica and clay. Sandy soil was found to have a positive slope at the longer wavelengths; the more clay rich soils had a negative slope. Spectra with a strong downturn at channel 50 generally indicated low vegetation cover, whereas an upturn indicated more vegetation cover. Mapping revealed a range of classified soils with varying amounts of quartz, silt, clay, and plant humus. Sand and gravel operations along the St. Vrain River, gravel lots, and some fields spectrally classified as quartz-rich sands were confirmed through field examination. Other fields mapped as sandy soils, ranging from quartz-rich sandy soil to quartz-rich silt-sand soil with clay. Flood plains mapped as sandy-silty-organic-rich clay. The city of Greeley contained all classes of materials, with the sand classes mapping as various types of asphalt. Abundant quartz gravel was apparent within the asphalt during field check-ing. The clay classes mapped silt-clay soils in areas of irrigated grass landscaping, some fields, and roofing materials.

Colorado↗

USGS2020

Statewide assessment of karst aquifers in New York with an inventory of closed-depression and focused-recharge features

Karst is a landscape formed from the dissolution of soluble rock or rock containing minerals that are easily dissolved from within the rock. The landscape is characterized by sinkholes, caves, losing streams, springs, and underground drainage systems, which rapidly move water through the karst. The two forms of karst in New York State include carbonate karst, which forms in carbonate rock (limestone, marble, and dolostone), and evaporite karst, which forms in rock that contains the evaporite minerals gypsum and halite. Past and recent studies of karst across the State have shown that areas of focused recharge in karstic carbonate rock allow contaminants to enter aquifer systems with little attenuation. Focused areas of recharge need to be identified to help prevent such contamination from sources on or adjacent to the karst. The New York State Departments of Environmental Conservation and Health are collaborating with the agricultural community to make farmers and farm-planning advisors more aware of karst and how to manage daily farming activities to reduce their impact on surface water and groundwater resources, especially in karst areas. There is also a need to make regulators, planners, and the general public aware of New York’s karst resources and to properly protect and manage these resources to protect the quality of groundwater and surface water that can flow into, through, and from karst bedrock. Using publicly available geospatial data, karst bedrock and closed depressions over or near karst rock were identified across New York. Carbonate, evaporite, and marble geologic units were selected from a statewide 1:250,000-scale bedrock geology dataset. The selected geologic units were intersected with 7.5-minute quadrangle maps to define the study area. The U.S. Geological Survey has compiled an inventory of closed depressions from statewide digital contour data, scanned 7.5-minute topographic maps known as a digital raster graphics, and light detection and ranging (lidar) digital elevation models. Analysis of the data resulted in the identification of 5,023 closed depressions statewide. The inventory was conducted to eliminate duplication of results from analysis of the three data sources. A series of overlay analyses was conducted using the closed depressions and thematic data known to be key factors in determining the probability of a closed depression contributing to focused groundwater recharge; the thematic data include bedrock geology, soil type, soil infiltration rate, and land cover. Though the extent of karst development is important in understanding the interaction between surface water and groundwater in karst terrains, some of the worst cases of groundwater contamination in karst can occur where only minor karst features might be present. The presence of karst—be it a short section of a solutioned fracture or an extensive cave system—requires careful consideration, forward-looking environmental planning, and consistent water-quality protection to preserve New York State’s water resources.

New York↗

USGS1976

Geological Survey and selected U.S. Bureau of Mines and Alaska Division of Geological and Geophysical Surveys reports and maps on Alaska released during 1975, indexed by quadrangle

All Geological Survey reports and maps on Alaska published or released to open files during 1975 are listed by the quadrangles (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 3). Also listed are U.S. Bureau of Mines reports on the geology and mineral resources of Alaska, but not those that deal exclusively with other subjects such as economics. Alaska Division of Geological and Geophysical Surveys published and open-filed reports and maps that were received by the Alaskan Geology Branch of the U.S. Geological Survey before March 1, 1976 are listed; the availability of several other reports and maps was publicly announced, but the documents were not available to me in time for them to be included here. Most of the reports and maps in this index bear a 1975 imprint date. Others bear earlier imprint dates, but were not released until 1975. All Alaska Division of Geological and Geophysical Surveys open-file reports and maps were withdrawn in 1974 for revision, consolidation, or assignment of new identification numbers. Those reissued reports and maps that I received before March 1, 1976 are listed in this index, no matter what imprint date they may bear. Also included are a few reports that were released before 1975, but hitherto had escaped my attention. Reports that deal with Alaska as a whole, with areas that can not be identified with a specific quadrangle, or that are mainly statistical presentations are listed under ALASKA - GENERAL, as are indexes and the like. Reports and maps that deal with offshore areas not within quadrangle boundaries are listed under OFFSHORE AREAS. The ALASKA - GENERAL and OFFSHORE AREAS lists appear before the alphabetically arranged quadrangle listings.

Alaska↗

USGS2012

Porphyry copper assessment of the Mesozoic of East Asia: China, Vietnam, North Korea, Mongolia, and Russia: Chapter G in Global mineral resource assessment

The U.S. Geological Survey (USGS) collaborated with the China Geological Survey (CGS) to conduct a mineral resource assessment of Mesozoic porphyry copper deposits in East Asia. This area hosts several very large porphyry deposits, exemplified by the Dexing deposit in eastern China that contains more than 8,000,000 metric tons of copper. In addition, large parts of the area are undergoing active exploration and are likely to contain undiscovered porphyry copper deposits. Three tracts were delineated to be permissive for Mesozoic porphyry copper deposits in East Asia: the Manchuride, Coastal Pacific, and East Qinling tracts, all Jurassic through Cretaceous in age. The tracts are based on mapped and inferred subsurface distributions of igneous rocks that define areas where the occurrence of porphyry copper deposits is possible. These tracts range in area from about 170,000 to about 1,400,000 km 2 . Although maps at a variety of scales were used in the assessment, the final tract boundaries are intended for use at a scale of 1:1,000,000. These Mesozoic deposits in East Asia all formed in post-subduction environments, environments newly recognized as permissive for the occurrence of porphyry copper deposits. Based on the grade, tonnage, and geologic characteristics of the known deposits, two tracts, Manchuride and Coastal Pacific, were evaluated using the general (Cu-Mo-Au) porphyry copper grade and tonnage model. The East Qinling tract was evaluated using the molybdenum-rich (Cu-Mo) model. Assessment participants estimated numbers of undiscovered deposits at different levels of confidence for each permissive tract. These estimates were then combined with the selected grade and tonnage models using Monte Carlo simulation to generate quantitative probabilistic estimates of undiscovered resources. Resources in future extensions of deposits with identified resources were not specifically evaluated. Assessment results, presented in tables and graphs, show mean amounts of metal and rock in undiscovered deposits at different quantile levels, as well as the arithmetic mean for each tract. This assessment estimated a mean total of about 44 undiscovered porphyry copper deposits within the assessed permissive tracts in East Asia. This represents nearly 4 times the 12 known deposits. Predicted mean (arithmetic) resources that could be associated with these undiscovered deposits are about 198,000,000 metric tons (t) of copper and about 3,900 t of gold, as well as byproduct molybdenum and silver. The reported identified resources for those 12 known deposits total about 23,000,000 t of copper and about 850 t of gold. The assessment area is estimated to contain nearly nine times as much copper in undiscovered porphyry copper deposits as has been identified to date. This report includes an overview of the assessment results and summary tables. Descriptions of each tract are included in appendixes, with estimates of numbers of undiscovered deposits, and probabilistic estimates of amounts of copper, molybdenum, gold, and silver that could be contained in undiscovered deposits for each permissive tract. A geographic information system that accompanies the report includes tract boundaries and a database of known porphyry copper deposits and prospects.

Scientific Investigations Report↗

USGS2012

Porphyry copper assessment of the Tibetan Plateau, China: Chapter F in Global mineral resource assessment

The U.S. Geological Survey collaborated with the China Geological Survey to conduct a mineral-resource assessment of resources in porphyry copper deposits on the Tibetan Plateau in western China. This area hosts several very large porphyry deposits, exemplified by the Yulong and Qulong deposits, each containing at least 7,000,000 metric tons (t) of copper. However, large parts of the area are underexplored and are likely to contain undiscovered porphyry copper deposits. Three tracts were delineated as permissive for porphyry copper deposits on the Tibetan Plateau—the Yulong (Eocene and Oligocene), Dali (Eocene through Miocene), and Gangdese (Oligocene and Miocene) tracts. The tracts were defined based on mapped and inferred subsurface distributions of igneous rocks of specific age ranges in which the occurrence of porphyry copper deposits is possible. These tracts range in area from about 95,000 to about 240,000 square kilometers. Although maps of different scales were used in the assessment, the final tract boundaries are intended for use at a scale of 1:1,000,000. The deposits on the Tibetan Plateau all formed in a post-subduction environment, one newly recognized as permissive for the occurrence of porphyry copper deposits. Based on the grade, tonnage, and geologic characteristics of the known deposits, two tracts, Yulong and Gangdese, were evaluated using the general (Cu-Mo-Au) porphyry copper grade and tonnage model. The Dali tract was evaluated using the gold-rich (Cu-Au) submodel. Assessment participants estimated numbers of undiscovered deposits at different levels of confidence for each permissive tract. These estimates were then combined with the selected grade and tonnage models using Monte Carlo simulation to generate quantitative probabilistic estimates of undiscovered resources. Additional resources in extensions of deposits with identified resources were not specifically evaluated. Assessment results, presented in tables and graphs, show mean expected amounts of metal and rock in undiscovered deposits at different quantile levels, as well as the arithmetic mean for each tract. This assessment estimated a mean of 39 undiscovered porphyry copper deposits within the assessed permissive tracts on the Tibetan Plateau. This represents nearly four times the number of known deposits (11) already discovered. Predicted mean (arithmetic) resources that could be associated with the undiscovered deposits are about 145,000,000 t of copper and about 4,900 t of gold, as well as byproduct molybdenum and silver. Reliable reports of the identified resources in the 11 known deposits total about 27,000,000 t of copper and about 800 t of gold. Therefore, based on the assessments of undiscovered Tibetan Plateau resources in this report, about six times as much copper may occur in undiscovered porphyry copper deposits as has been identified to date.

Tibetan Plateau↗

USGS1978

Geochemical map showing the distribution and abundance of copper in stream sediments in the Seward and Blying Sound quadrangles, Alaska

Reconnaissance geochemical and mineralogical sampling was done in the Seward and Blying Sound quadrangles during 1975 and 1976 as part of the Alaska Mineral Resources Assessment Program (AMRAP). This map shows the distribution and abundance of copper in stream-sediment samples. Stream-sediment samples were collected at 569 sites from active stream channels and locally, from the interface of streambeds with intermediate- to low-tide beaches. Most of the stream sediment is fine- to coarse-grained sand, with a clay-silt fraction in streams discharging from glaciers. The stream sediment samples were air dried and sieved through a 80-mesh (0.2 mm) sieve, and the minus-80 mesh fraction was saved for analysis. A split of each sample was analyzed for copper and 15 other elements by a semiquantitative spectrographic method (Grimes and Marranzino, 1968). Other splits were analyzed for gold and zinc by atomic absorption methods (Warren and others, 1969). Sample sites and copper values (in parts per million) are indicated on the map by symbols identified in the histogram. The weakly anomalous values are considered to be significant only where they were detected in stream-sediment or heavy-mineral concentrate samples that also contained strongly anomalous values of other metals such as arsenic, gold, lead or tungsten. The map shows two populations for copper in stream sediments. One population consisting of generally lower copper values represents the samples collected from the sedimentary terrane in the central and western parts of the quadrangles. The other population consisting of generally higher copper values includes samples collected in areas of sheeted basalt dikes and pillow basalts in the eastern part of the quadrangles and from the sedimentary terrane of Latouche Island; in these areas chalcopyrite and pyrite were observed as fine-grained disseminations in the rocks and as mineral particles in the heavy-mineral concentrates.

Alaska↗

USGS1984

Generalized thickness and configuration of the top of the intermediate aquifer, west-central Florida

Generalized map show the thickness and top of the intermediate aquifer in west-central Florida within the boundaries of the Southwest Florida Water Management District. The intermediate aquifer consists of a series of water-bearing units and confining beds between the surficial aquifer (water table) and the Floridan aquifer. This aquifer contains from one to several water-bearing units in west-central Florida. The aquifer and confining beds consist of the Tamiami and Hawthorn Formations of late and middle Miocene age and parts of the Tampa Limestone of early Miocene age. The top of the intermediate aquifer is about 100 feet above sea level in the north and slopes to about 100 feet below sea level in the south. The thickness ranges from zero in the north to more than 600 feet in the south. Despite the high mineral content of the water in some areas, the intermediate aquifer offers the best source of ground water to the coastal and southern areas of west-central Florida. (USGS)

Water-Resources Investigations Report↗

USGS2021

Groundwater hydrology and chemistry of Jamestown Island, Virginia—Potential effects of tides, storm surges, and sea-level rise on archaeological, cultural, and ecological resources

As the site of the first permanent English settlement in North America in 1607, Jamestown Island, Colonial National Historical Park (COLO), Virginia, contains a rich archaeological record that extends from the Paleoindian period (15,000 to 8,000 years ago) through the 20th century. The island is located on the lower James River near the mouth of Chesapeake Bay. Jamestown Island vegetation is dominated by upland forests surrounded by tidal, freshwater-to-oligohaline marshes. Along the Virginia coast, relative sea-level rise was more than 2.5 times the global average during the 20th century. Consequently, the National Park Service (NPS) has identified COLO as one of the 25 national parks most threatened by climate change. Surface waters across the island are hydraulically connected to the laterally continuous Surficial aquifer. The land-surface altitude of the island is low, with two-thirds of the island less than 5 feet (ft) above the North American Vertical Datum of 1988 (NAVD 88). Consequently, sea-level rise, combined with tides and storm surges, threatens the island and its resources as surface-water and groundwater levels rise, saltwater enters the Surficial aquifer, and groundwater chemistry changes. The impact of sea-level rise on the island’s surface-water resources has been well studied, but groundwater effects have been largely ignored. Quantifying the effects of tides, storm surges, and sea-level rise on groundwater levels and chemistry is essential to developing an effective strategy for managing climate-induced changes. The first step in developing a response strategy includes a parkwide general risk assessment for archaeological sites on the island, so that sites can be prioritized for management actions. The U.S. Geological Survey and the NPS began a study in 2015 to develop a long-term groundwater-monitoring program to evaluate this risk and to develop an updated management strategy. The groundwater-monitoring program consists of 45 wells and piezometers in two individual clusters and three transects across the island in different hydrologic and chemical settings. Samples for water quality were collected from the wells and piezometers from October 2015 through September 2018 at variable time intervals. Results of the monitoring identified disparate hydrologic and chemical responses to saltwater intrusion across the island. Specific conductance (an indicator of salinity) of groundwater beneath several marshes responded differently to changes in James River salinity. Groundwater response to changes in James River specific conductance appeared to be controlled by land-surface altitude and slope, differences in lateral and vertical sediment characteristics, distance from surface waters, and the degree of surface water/groundwater connectivity between channels and the aquifer. Groundwater chemistry data from monitoring wells at Black Point, a low-altitude, upland setting, are in contrast with conditions observed in Island House observation wells, a high-altitude, upland setting. Specific conductance (less than 200 microsiemens per centimeter [μS/cm]) and pH (greater than 5.0) of groundwater beneath much of the uplands that characterize the Island House observation wells are typical of groundwater in noncarbonate sedimentary aquifers recharged by precipitation. At Black Point, specific conductance ranged from 2,490 to 15,200 μS/cm, and pH ranged from 3.1 to 6.6 standard units. At the Black Point observation wells, the most saline and dense water was at the water table rather than deeper in the aquifer, causing a density inversion that persisted throughout the study. The density inversion likely resulted from differences in permeability between the shallow clay and fine-grained sands and the deeper coarse-grained sand and gravel. Groundwater with the lowest pH was at the water table. As saline groundwater flows through organic sediment beneath the marshes, bacterial biodegradation of organic matter creates anoxic conditions. Continued biodegradation concomitantly reduces iron-oxide minerals in the sediment and sulfate in saline water. When oxygen is reintroduced into groundwater, iron and sulfur can reoxidize to form sulfuric acid, locally lowering the pH of the water. This report describes the groundwater monitoring network design, rationale for site selection, monitoring approach, and results of monitoring from October 2015 through September 2018. Maps of inundation at selected water-level altitudes are included to identify the risk to archaeological, cultural, and ecological resources. The monitoring results of the hydrology and chemistry data are interpreted, and the different hydrologic and chemical settings are described. The implications of the study results for management decisions are presented, and suggestions for improving the monitoring network are included.

Virginia↗

USGS2019

Distribution of mineral phases in the Eocene Green River Formation, Piceance Basin, Colorado – Implications for the evolution of Lake Uinta

The mineralogy of the Eocene Green River Formation in the Piceance Basin, Colorado, has been the subject of numerous studies since the 1920s. Most previous work has focused on the resource potential of these lacustrine mudrocks, which in addition to substantial oil shale potential (in-place resources of 353 billion barrels of synthetic crude oil for rocks yielding at least 25 gallons per ton, GPT), includes nahcolite, a currently utilized soda ash resource, and dawsonite, a potential alternative source of aluminum. Another reason to study the mineralogy in this system is that the geographic and stratigraphic distribution of various authigenic minerals may provide insights into the geochemistry and depositional environment of the long-lived Eocene Lake Uinta. In this study, legacy non-quantitative (presence/absence) X-ray diffraction (XRD) data recently published by the U.S. Geological Survey (USGS) for more than nine-thousand samples collected from thirty coreholes in the Green River Formation, Piceance Basin were examined. These data were used to better define the stratigraphic and paleogeographic extent of a set of indicator minerals (illite, analcime, albite, dawsonite, and nahcolite) within the Piceance Basin lacustrine strata. This set of minerals was selected based on observations from previous work and variability in their occurrence and co-occurrence within the Piceance Basin. The USGS database has been used to (1) construct maps showing geographic variations in mineral occurrences for 14 stratigraphically defined rich and lean oil shale zones; (2) assess co-occurrences of indicator minerals; and (3) compare occurrence results with quantitative XRD datasets collected on Piceance Basin oil shales. Occurrences of many authigenic minerals (analcime, dawsonite, and nahcolite) varied in the lacustrine strata near and around the depocenter, but others, like quartz, dolomite, and feldspar (potassium + undifferentiated), were widely and consistently present (>90% of samples) across the basin. Shifts in the distribution of indicator mineral occurrences generally coincide with changes identified in previous lake history descriptions and indicate that the water chemistry of Lake Uinta varied significantly going from near-shore to the depocenter and through time.

Colorado↗

USGS2006

Bedrock Geologic Map of New Hampshire, a Digital Representation of Lyons and Others 1997 Map and Ancillary Files

The New Hampshire Geological Survey collects data and performs research on the land, mineral, and water resources of the State, and disseminates the findings of such research to the public through maps, reports, and other publications. The Bedrock Geologic Map of New Hampshire, by John B. Lyons, Wallace A. Bothner, Robert H. Moench, and James B. Thompson, was published in paper format by the U.S. Geological Survey (USGS) in 1997. The online version of this CD contains digital datasets of the State map that are intended to assist the professional geologist, land-use planners, water resource professionals, and engineers and to inform the interested layperson. In addition to the bedrock geology, the datasets include geopolitical and hydrologic information, such as political boundaries, quadrangle boundaries, hydrologic units, and water-well data. A more thorough explanation for each of these datasets may be found in the accompanying metadata files. The data are spatially referenced and may be used in a geographic information system (GIS). ArcExplorer, the Environmental Systems Research Institute's (ESRI) free GIS data viewer, is available at http://www.esri.com/software/arcexplorer. ArcExplorer provides basic functions that are needed to harness the power and versatility of the spatial datasets. Additional information on the viewer and other ESRI products may be found on the ArcExplorer website. Although extensive review and revisions of the data have been performed by the USGS and the New Hampshire Geological Survey, these data represent interpretations made by professional geologists using the best available data, and are intended to provide general geologic information. Use of these data at scales larger than 1:250,000 will not provide greater accuracy. The data are not intended to replace site-specific or specific-use investigations. The U.S. Geological Survey, New Hampshire Geological Survey, and State of New Hampshire make no representation or warranty, expressed or implied, regarding the use, accuracy, or completeness of the data presented herein, or from a map printed from these data; nor shall the act of distribution constitute any such warranty. The New Hampshire Geological Survey disclaims any legal responsibility or liability for interpretations made from the map, or decisions based thereon. For more information on New Hampshire Geological Survey programs please visit the State's website at http://des.nh.gov/Geology/. New Hampshire Geographically Referenced Analysis and Information Transfer System (NH GRANIT) provides access to statewide GIS (http://www.granit.unh.edu/). Questions about this CD or about other datasets should be directed to the New Hampshire Department of Environmental Services.

Data Series↗

USGS2011

Recovery and reprocessing of legacy geophysical data from the archives of the State Company of Geology and Mining (GEOSURV) of Iraq and Iraq Petroleum Company (IPC)

Aeromagnetic data belonging to the State Company of Geology and Mining of Iraq (GEOSURV) have been recovered from magnetic tapes and early paper maps. In 1974 a national airborne survey was flown by the French firm Compagnie General de Geophysique (CGG). Following the survey the magnetic data were stored on magnetic tapes within an air conditioned archive run by GEOSURV. In 1990, the power supply to the archive was cut resulting in the present‐day poor condition of the tapes. Frontier Processing Company and the U.S. Geological Survey (USGS) have been able to recover over 99 percent of the original digital data from the CGG tapes. Preliminary reprocessing of the data yielded a total magnetic field anomaly map that reveals fine structures not evident in available published maps. Successful restoration of these comprehensive, high quality digital datasets obviates the need to resurvey the entire country, thereby saving considerable time and money. These data were delivered to GEOSURV in a standard format for further analysis and interpretation. A parallel effort by GETECH concentrated on recovering the legacy gravity data from the original field data sheets archived by IPC (Iraq Petroleum Company). These data have been compiled with more recent GEOSURV sponsored surveys thus allowing for the first time a comprehensive digital and unified national gravity database to be constructed with full principal facts. Figure 1 shows the final aeromagnetic and gravity data coverage of Iraq. The only part of Iraq lacking gravity and aeromagnetic data coverage is the mountainous areas of the Kurdish region of northeastern Iraq. Joint interpretation of the magnetic and gravity data will help guide future geophysical investigations by GEOSURV, whose ultimate aim is to discover economical mineral and energy resources.

SEG Technical Program Expanded Abstracts↗

USGS1992

Maps showing mineral resource assessment for vein and replacement deposits of base and precious metals, barite, and fluorspar, Dillon 1° x 2° quadrangle, Idaho and Montana

This report is one of several that assess the mineral resources in the Dillon quadrangle. For the purpose of the assessment, the deposits that are known in the quadrangle, or suspected to be present from a knowledge of the geologic setting, have been grouped into 30 deposit types on the basis of the mineralogy or commodity in the ore and the structural or depositional setting of the deposit. The emphasis in these assessment reports is on metallic minerals, but some important nonmetallic minerals are also considered. Fossil fuels are beyond the scope of this investigation, phosphate and uranium have been investigated previously (Swanson, 1970; Wodzicki and Krason, 1981 ), and certain nonmetallic minerals, including bulk commodities such as sand and gravel, are in large supply and thus are not considered. The mineral resource assessment discussed in this report concentrates on a single deposit type (of the total of 30 types) that we call "vein and replacement deposits of base and precious metals." Base and precious metals produced from such deposits are copper, lead, zinc, gold, and silver. Vein deposits of barite and fluorspar are also discussed, but because they seem to be of minor importance, they are treated briefly. Vein and replacement deposits of base and precious metals are classified as a single deposit type rather than as numerous possible subordinate types that might be distinguished on the basis of mineralogy, metal content, or other factors, because the characteristics of the ore, the ore bodies, and the structural setting are not sufficiently well known to yield a consistent detailed classification for the entire quadrangle. Furthermore, the criteria used here to explain the localization of deposits are too general to allow discrimination among subordinate types at a scale of 1 :250,000 or smaller. In assessing mineral resources, we have adopted a general philosophy similar to that of Harrison and others ( 1986). We attempt to identify parts of the quadrangle that are favorable for the occurrence of mineral resources, and we make an assignment of the relative resource potential of all parts of the quadrangle. We do not attempt to locate specific exploration targets nor to determine the quantity of reserves or resources present.

Idaho, Montana↗

USGS1989

The United States Geological Survey: 1879-1989

The United States Geological Survey was established on March 3, 1879, just a few hours before the mandatory close of the final session of the 45th Congress, when President Rutherford B. Hayes signed the bill appropriating money for sundry civil expenses of the Federal Government for the fiscal year beginning July 1, 1879. The sundry civil expenses bill included a brief section establishing a new agency, the United States Geological Survey, placing it in the Department of the Interior, and charging it with a unique combination of responsibilities: 'classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain.' The legislation stemmed from a report of the National Academy of Sciences, which in June 1878 had been asked by Congress to provide a plan for surveying the Territories of the United States that would secure the best possible results at the least possible cost. Its roots, however, went far back into the Nation's history. The first duty enjoined upon the Geological Survey by the Congress, the classification of the public lands, originated in the Land Ordinance of 1785. The original public lands were the lands west of the Allegheny Mountains claimed by some of the colonies, which became a source of contention in writing the Articles of Confederation until 1781 when the States agreed to cede their western lands to Congress. The extent of the public lands was enormously increased by the Louisiana Purchase in 1803 and later territorial acquisitions. At the beginning of Confederation, the decision was made not to hold the public lands as a capital asset, but to dispose of them for revenue and to encourage settlement. The Land Ordinance of 1785 provided the method of surveying and a plan for disposal of the lands, but also reserved 'one-third part of all gold, silver, lead, and copper mines to be sold or otherwise disposed of, as Congress shall thereafter direct,' thus implicitly requiring classification of the lands into mineral and nonmineral. Mapping of the public lands was begun under the direction of the Surveyor-General, but no special provision was made for classification of the public lands, and it thus became the responsibility of the surveyor. There was,of course, no thought in 1785 or for many years thereafter of employing geologists to make the classification of the mineral lands, for geology was then only in its infancy.

Circular↗

USGS2025

Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration

The Adirondack Mountains of New York, U.S.A. contain iron oxide-apatite (IOA) mineral deposits with variable concentrations of rare earth elements (REE). The IOA mineral deposits are typically hosted in the Lyon Mountain Granite Gneiss and are spatially correlated with extensive Na metasomatism (albitization) of the surrounding country rocks, although some mineral deposits also occur in metagabbro, paragneiss, and anorthosite hosts. The location of albitization zones is key to finding new IOA mineral deposits and better understanding the mineralization processes associated with their genesis. However, the Na alteration zones are generally not visibly identifiable in outcrop or hand specimens because the color and textural changes are subtle and are thus difficult to map. Here, we discuss the results from testing two spectroscopic techniques (handheld, field gamma-ray spectroscopy, and portable X-ray fluorescence (pXRF)) to characterize albitization zones surrounding IOA mineral deposits. The gamma-ray and pXRF spectrometers successfully distinguished the relative intensity of alteration in the Lyon Mountain Granite Gneiss based on the K abundance. The measured K content decreases towards the IOA mineral deposits, and the magnitude and width of the gradient are similar along the strike of each mineral deposit. Elevated Th and U values are present in host rocks adjacent to REE-bearing IOA mineral deposits. The pXRF and gamma-ray spectrometer K values are remarkably consistent with laboratory-based, whole-rock XRF compositional data and, therefore, useful for semi-quantitative analysis. Notably, albitization aureoles are consistent around REE-rich and REE-poor mineral deposits, suggesting that saline fluids are essential for the petrogenesis of IOA mineral deposits but may not be critical to REE mineralization. Ultimately, this study demonstrates the utility of handheld gamma-ray and pXRF spectrometry for identifying otherwise cryptic albitization gradients associated with IOA mineral deposits in granitic gneiss.

New York↗

USGS1974

Geology of quadrangles H-12, H-13, and parts of I-12 and I-13, (zone III) in northeastern Santander Department, Colombia

A program of geologic mapping and mineral investigation in Colombia was undertaken cooperatively by the Colombian Instituto Nacional de Investigaciones Geologico-Mineras (formerly known as the Inventario Minero Nacional), and the U. S. Geological Survey; by the Government of Colombia and the Agency for International Development, U. S. Department of State. The purpose was to study, and evaluate mineral resources (excluding of petroleum, coal, emeralds, and alluvial gold) of four selected areas, designated Zones I to IV, that total about 70,000 km2. The work in Zone III, in the Cordillera Oriental, was done from 1965 to 1968. The northeast trend of the Cordillera Oriental of Colombia swings abruptly to north-northwest in the area of this report, and divides around the southern end of the Maracaibo Basin. This section of the Cordillera Oriental is referred to as the Santander Massif. Radiometric age determinations indicate that the oldest rocks of the Santander massif are Precambrian and include high-grade gneiss, schist, and migmatite of the Bucaramanga Formation. These rocks were probably part of the Precambrian Guayana Shield. Low- to medium-grade metamorphic rocks of late Precambrian to Ordovician age .include phyllite, schist, metasiltstone, metasandstone, and marble of the Silgara Formation, a geosynclinal series of considerable extent in the Cordillera Oriental and possibly the Cordillera de Merida of Venezuela. Orthogneiss ranging from granite to tonalite is widely distributed in the high- and medium-grade metamorphic rocks of the central core of the massif and probably represents rocks of two ages, Precambrian and Ordovician to Early Devonian. Younger orthogneiss and the Silgara are overlain by Middle Devonian beds of the Floresta Formation which show a generally low but varying degree of metamorphism. Phyllite and argillite are common, and infrequent marble and other calcareous beds are fossiliferous. Except for recrystallization in limestones of !the Permian-Carboniferous Diamante Formation, sedimentary rocks younger than Devonian are unmetamorphosed. The effects of Precambrian regional dynamothermal metamorphism and plutonism on Precambrian geosynclinal deposits reached the upper amphibolite facies in the Bucaramanga Gneiss. The geosynclinal Silgara Formation was subjected to similar conditions in Late Ordovician and Early Silurian time but reached only the greenschist or lower amphibolite facies. Orthogneisses generally show a concordance of foliation and lineation with the neighboring Silgara Formation and the Bucaramanga Gneiss as well as similarities in grade of metamorphism. Regional dynamothermal metamorphism in Late Permian and Triassic time reached, low grade in the Floresta Formation and caused recrystallization of limestone of the Diamante Formation. The Bucaramanga and Silgara metamorphic rocks show evidence of metrogressive metamorphism accompanied by high activity or potassium and water, but whether this occurred at the time the Floresta was metamorphosed or later is not clear. Batholiths, plutons, and stocks of igneous rocks in the Santander massif range from diorite to granite. Radioactive age data indicate that most belong to a single plutonic interval. These are referred to as the Santander Plutoniq Group and are Jurassic and Jurassic-Triassic- Two suites of this group are pink granite and quartz monzonite, and gray quartz monzonite and granodiorite. Contact relations indicate that the pink and more granitic rocks are younger than the gray and more mafic rocks, but radioactive age data are in conflict with this. Undated plutonic rocks that are not clearly related to the group are assigned to relatively older or younger age positions. West of the Bucanamanga fault rhyolite makes up a small body at one locality and forms an intrusive sheet with granophyre and intrusive breccias in Triassic sedimentary rocks at another locality. Its age is unknown, but it probably is younger than the

Open-File Report↗

USGS1976

Water availability, quality, and use in Alaska

The Alaska Water Assessment, sponsored by the Water Resources Council, is a specific problem analysis for Alaska of the National Assessment of Water and Related Land Resources. The assessment addresses water and water-related land problems, present and future. It was felt that a supplementary report, as a part of the assessment, was needed to state in general terms the present hydrologic conditions, including the availability, quality, and use of both surface water and ground water in the Alaska region. Alaska covers an area of 586,412 square miles, about one-fifth of the total area of the United States. Characteristic of parts of the region is the presence of permafrost. The physiography of Alaska ranges from low coastal plains of the Arctic and deltas of the major rivers to peaks of the Alaska Range. Climate in the State ranges from the maritime rain forests of southeast Alaska to the frozen desert of the Arctic. Mean annual runoff for the region is estimated at 1,260,000 cubic feet per second which includes an estimated 163,000 cubic feet per second of inflow from Canada. The Alaska region has been divided into six hydrologic subregions and eighteen subareas. For each subarea, estimated mean annual runoff per square mile, suspended-sediment concentrations that can be expected during "normal" summer runoff and, where data are available, flood magnitudes and frequencies are illustrated on maps. Also illustrated are estimated ground-water yields in each subarea. Tables listing water quality of both ground water and surface water from selected wells and streams are also included. Water use according to the type of use is discussed, and estimates are given for the amounts used. Water-use categories in the State include domestic, irrigation, livestock, seafood processing, oil and gas development, petrochemical processing, pulp mills, hydroelectric, coal processing, steam electric, mineral processing, sand and gravel mining, and fish-hatchery operations. Also illustrated on maps are estimated ground-water yields in each subarea. Tables listing water quality of both ground water and surface water from selected wells and streams are also included.

Alaska↗

USGS2013

Knowledge and understanding of dissolved solids in the Rio Grande–San Acacia, New Mexico, to Fort Quitman, Texas, and plan for future studies and monitoring

Availability of water in the Rio Grande Basin has long been a primary concern for water-resource managers. The transport and delivery of water in the basin have been engineered by using reservoirs, irrigation canals and drains, and transmountain-water diversions to meet the agricultural, residential, and industrial demand. In contrast, despite the widespread recognition of critical water-quality problems, there have been minimal management efforts to improve water quality in the Rio Grande. Of greatest concern is salinization (concentration of dissolved solids approaching 1,000 mg/L), a water-quality problem that has been recognized and researched for more than 100 years because of the potential to limit both agricultural and municipal use. To address the issue of salinization, water-resource managers need to have a clear conceptual understanding of the sources of salinity and the factors that control storage and transport, identify critical knowledge gaps in this conceptual understanding, and develop a research plan to address these gaps and develop a salinity management program. In 2009, the U.S. Geological Survey (USGS) in cooperation with the U.S. Army Corps of Engineers (USACE), New Mexico Interstate Stream Commission (NMISC), and New Mexico Environment Department (NMED) initiated a project to summarize the current state of knowledge regarding the transport of dissolved solids in the Rio Grande between San Acacia, New Mexico, and Fort Quitman, Texas. The primary objective is to provide hydrologic information pertaining to the spatial and temporal variability present in the concentrations and loads of dissolved solids in the Rio Grande, the source-specific budget for the mass of dissolved solids transported along the Rio Grande, and the locations at which dissolved solids enter the Rio Grande. Dissolved-solids concentration data provide a good indicator of the general quality of surface water and provide information on the factors governing salinization within the Rio Grande study area. The pattern in dissolved-solids concentrations along the Rio Grande is one of increasing concentration with increasing distance downstream from Elephant Butte and Caballo Reservoirs. The concentration of dissolved solids in the Rio Grande doubles (approximately 500 to 1,000 mg/L) from below Elephant Butte Reservoir to El Paso and increases by more than a factor of 5 (approximately 500 to 3,200 mg/L) from below Elephant Butte Reservoir to Fort Quitman. Marked increases in the concentration of dissolved solids commonly coincide with contributions from agricultural drains, wastewater-treatment plants, regional groundwater, and upward-flowing saline groundwater. The greatest factor, from the surface-water system, in controlling dissolved solids in the Rio Grande is the amount of water that is being transported or stored. Annual variation in streamflow is influenced primarily by climate (precipitation and evaporation) and management of Elephant Butte and Caballo Reservoirs (water storage and release cycles). Seasonal variation in streamflow within the Rio Grande study area is generally categorized generally as irrigation (March–September) and nonirrigation (October–February) seasons; with streamflow in the Rio Grande is highest during the irrigation season and lowest during the nonirrigation season. Dissolved-solids loads during the irrigation season decrease between Leasburg and Fort Quitman primarily because of irrigation diversions and losses to the underlying alluvial aquifer. Conversely, dissolved-solids loads during the nonirrigation season increase between Caballo Dam and Fort Quitman primarily because of the inflow of dissolved solids from agricultural drains, wastewater-treatment plants, and groundwater with elevated concentrations of dissolved solids. Many studies have mass-balance budgets that account for the mass of dissolved solids transported along the Rio Grande. Results from mass-balance budgets developed for dissolved solids indicated that (1) the inflow of saline groundwater, inflow of regional groundwater, and chemical reactions between mineral phases are the primary sources controlling dissolved solids in the Rio Grande, and (2) groundwater pumping and mineral precipitation are causing a net storage of dissolved solids in the Leasburg to El Paso and El Paso to Fort Quitman reaches of the Rio Grande. Looking forward, multiple water-resource managers from State and local agencies in New Mexico and Texas and Federal agencies formed the Rio Grande Salinity Management Coalition with the goal to reduce the amount of dissolved solids that are transported and stored in the Rio Grande study area. The recommendations for additional monitoring to assist the coalition are as follows: -Monitoring: Couple water-quality and streamflow monitoring in the Rio Grande and agricultural drains; perform groundwater-seepage investigations in the Rio Grande and major agricultural drains; nonitor groundwater water-quality conditions in the Mesilla and Hueco Basins. -Focused Hydrogeology Studies at Inflow Sources: Map dissolved-solids concentrations in the Rio Grande and underlying alluvial aquifer; perform hydrogeologic characterization of subsurface areas containing unusually high concentrations of dissolved solids. -Modeling of Dissolved Solids: Develop models to simulate the transport and storage of dissolved solids in both surface-water and groundwater systems.

New Mexico;Texas↗