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USGS2010

Mineral resource of the month: perlite

The article talks about perlite, which is a mineral used as an aggregate for lightweight construction products, filler for paints and horticultural soil blends. Perlite comes from viscous lava, mined and processed to produce lightweight material that competes with pumice, exfoliated vermiculite and expanded clay and shale. It is mined in about 35 countries that include Greece, Japan and the U.S. Other uses include insulation, concrete and plaster aggregate, and stonewashing.

Earth↗

USGS1999

Environmental models of mineral deposits- A state of the art

Although mineral deposits have been classified by their geologic and mineralogical characteristics for decades, the recognition that mineral deposits also could be classified by their environmental characteristics is relatively new. In the past 5 years, numerous advancements have been made in this subject area, building on the earlier work of economic geologists who classified geologic characteristics. Several different approaches to understanding the environmental behavior of mineral deposits and associated altered areas have been taken, ranging from wholesale assessments of large areas (millions of km 2 ) to detailed assessments of individual watersheds or individual mines. While these first attempts have succeeded in describing some of the environmental characteristics of ore deposits in a number of ways, many important “environmental variables” are not included in present descriptive models. For example, the models should be expanded in scope to include a more thorough treatment of climatic and ecoregional effects- embodying such physical environmental characteristics as precipitation, evaporation, temperature, and ground water-surface water interactions. More complete model descriptions will have applications to the determination of baselines and natural backgrounds in mined and unmined areas, as well as possible anticipated effects of new mining in a given area, and mitigation and remediation strategies. The challenge to geologists and geochemists is to incorporate a widely disparate set of physical and chemical characteristics of mineralized and altered zones at scales ranging from microscopic (sub-millimeter) to macroscopic (10’s to 100’s of kilometers). This paper presents an overview of the development of mineral deposit environmental models, the current state of the art, an evaluation of needed improvements, and expected advancements in this field.

Geologica Hungarica. Series geologica↗

USGS2000

Evolution of the Creede Caldera and its relation to mineralization in the Creede mining district, Colorado

At 25 Ma a major epithermal silver and base metal deposit formed in rhyolitic welded tuff near Creede, Colorado. Nearly 24000 metric tons of silver, appreciable lead, and small amounts of zinc, copper, and gold, have been produced from large, crustified veins under Bachelor and Bulldog Mountains north and northwest of Creede. Prior geologic, hydrologic, and stable-isotope studies showed that ore deposition was associated with the mixing and boiling of waters from diverse sources and suggester that a critical part of the ore-forming fluid may have originated within the ancient lake and sediments of the lacustrine Creede Formation that filled the Creede caldera. Two drill holes that sampled the heretofore hidden lower half of the Creede Formation are the focus of this book. The Creede caldera formed at 26.9 Ma within a high constructional plateau of silicic ashflows that covered and were sporadically interlayed with, intermediate lavas and lahars from large stratovolcanoes. The Creede caldera lake had an inflow evaporation balance that did not permit rapid filling to create a brim-full deep lake. Thus salts were evaporatively concentrated; but, with the exception of possible gypsum, no evaporite minerals preserved. Cool springs deposited travertine as mounds and contributed to limestone interlaminations within the sediment. The lake bottom was anoxic, and bacterial reduction of sulfate led to extreme sulfur isotopic fractionation in diagenetic pyrite. The caldera gradually resurged, converting the initial equant lake into an arcuate moat. Resurgent doming, alluvial fans, lacustrine sediments, ashfalls, and lava domes displaced water, lifted the lake so that it overlapped what later became the southern edge of the mineralized are, and eventually filled the basin. At 25.1 Ma an unseen pluton intruded beneath the northen part of the Creede district and created a convecting olume that drew in brine from the Creede caldera fill, meteotic water from highlands to the north, and possibly a fluid carrying radiogenic lead. These waters mixed and boiled as they approached the surface and moved southward, deposited a zoned epithermal deposit a few hundred meters below the paleosurface, and finally discharged into the top of the Creede Formation. The sulfide in the ores was the igneous derivation, but the sulfate was a mixture of biogenic sulfur from the Creede Formation, oxidized igneous sulfide, and thermochemically reduced and partially oxygen exchanged sulfate. The studies of the Creede caldera provide key observational and conceptual elements for the generalized model of the Creede ore deposit. The relation of the Creed ore deposit to a brine reservoir has broad significance because other brine accumulations (as in the Great Basin, the Green River Basin, or the playas of the Altiplano offer similar setting and exploration opportunities.

Colorado↗

USGS1998

Geological factors affecting the distribution of trace metals in glacial sediments of central Newfoundland

In central Newfoundland (NTS 12A/10, 15, 16, 2H/1), As, Pb, and Zn concentrations in the clay-sized (< 0.002 mm) and silt and clay-sized (< 0.063 mm) fractions of till reflect compositional differences among and within rock terranes at scales of kilometers to tens of kilometers. In those fractions, till derived from volcanic bedrock of Victoria Lake Group (Tulks Hill) is notably enriched in As (50- > 1000 ppm), exceeding levels commonly set for purposes of environmental protection. Near Pb-Zn mines at Buchans, geochemical variation with depth reflects the dispersal of detritus from mineralized bedrock, and differences in sediment type and provenance. There, surface sediments are rich in granitic debris derived from the Topsails igneous terrane 5 km north of Buchans and contain low concentrations of trace metals. These sediments are compositionally unrelated to either Buchans Group volcanic rock or an underlying, older till enriched in sulphide minerals and trace metals. Metal-rich till extending up to 10 km southwest of Buchans results from combined glacial and debris flow transport related to two distinct geological events. Trace metals are enriched (two- to fourfold) in the clay-sized fraction of till compared to the silt and clay-sized, and are associated with Al- and Mg-bearing minerals that preferentially concentrate in the clay fraction. The geochemistry of the silt and clay-sized fraction can approximate that of the < 2-mm fraction. Background variations in till illustrate the important role of a geological framework to the interpretation of geochemical surveys and the origins of trace metals in the environment.

Environmental Geology↗

USGS1989

Soil geochemistry of Mother Lode-type gold deposits in the Hodson mining district, central California, U.S.A.

The Hodson mining district is in the westernmost foothills of the Sierra Nevada in California, about 17 km west of the town of Angels Camp. This district is part of the West Gold Belt, which lies about 12-16 km west of, and generally parallel to, the better known Mother Lode Gold Belt in central California. The district produced several million dollars worth of Au between about 1890 and 1940. The geologic setting and mineral deposits in the West Gold Belt are generally similar to those in the Mother Lode Gold Belt. Rocks in the study area are of Jurassic age and consist of a mixture of (1) fine-grained, generally thin-bedded, clastic sedimentary rocks that have been metamorphosed to slates, schists, and phyllites, and (2) massive volcanic flows and welded tuffs that have been metamorphosed to metabasalts and metatuffs. All rocks were intensely faulted and folded during the Late Cretaceous Nevadan orogeny; northnorthwest- and northwest-trending faults dominate. Mining in the area was of low-grade gold-pyrite ores occurring principally in the carbonatized wall rocks adjacent to the major northwest-trending Hodson fault and its splays. Minor amounts of other sulfide minerals (principally chalcopyrite, arsenopyrite, sphalerite, and galena) are locally associated with the Au deposits.

California↗

USGS1998

Assessment of the hydraulic connection between ground water and the Peace River, west-central Florida

The hydraulic connection between the Peace River and the underlying aquifers along the length of the Peace River from Bartow to Arcadia was assessed to evaluate flow exchanges between these hydrologic systems. Methods included an evaluation of hydrologic and geologic records and seismic-reflection profiles, seepage investigations, and thermal infrared imagery interpretation. Along the upper Peace River, a progressive long-term decline in streamflow has occurred since 1931 due to a lowering of the potentiometric surface of the Upper Floridan aquifer by as much as 60 feet because of intensive ground-water withdrawals for phosphate mining and agriculture. Another effect from lowering the potentiometric surface has been the cessation of flow at several springs located near and within the Peace River channel, including Kissengen Spring, that once averaged a flow of about 19 million gallons a day. The lowering of ground-water head resulted in flow reversals at locations where streamflow enters sinkholes along the streambed and floodplain. Hydrogeologic conditions along the Peace River vary from Bartow to Arcadia. Three distinctive hydrogeologic areas along the Peace River were delineated: (1) the upper Peace River near Bartow, where ground-water recharge occurs; (2) the middle Peace River near Bowling Green, where reversals of hydraulic gradients occur; and (3) the lower Peace River near Arcadia, where ground-water discharge occurs. Seismic-reflection data were used to identify geologic features that could serve as potential conduits for surface-water and ground-water exchange. Depending on the hydrologic regime, this exchange could be recharge of surface water into the aquifer system or discharge of ground water into the stream channel. Geologic features that would provide pathways for water movement were identified in the seismic record; they varied from buried irregular surfaces to large-scale subsidence flexures and vertical fractures or enlarged solution conduits. Generally, the upper Peace River is characterized by a shallow, buried irregular top of rock, numerous observed sinkholes, and subsidence depressions. The downward head gradient provides potential for the Peace River to lose water to the ground-water system. Along the middle Peace River area, head gradients alternate between downward and upward, creating both recharging and discharging ground-water conditions. Seismic records show that buried, laterally continuous reflectors in the lower Peace River pinch out in the middle Peace River streambed. Small springs have been observed along the streambed where these units pinch out. This area corresponds to the region where highest ground-water seepage volumes were measured during this study. Further south, along the lower Peace River, upward head gradients provide conditions for ground-water discharge into the Peace River. Generally, confinement between the surficial aquifer and the confined ground-water systems in this area is better than to the north. However, localized avenues for surface-water and ground-water interactions may exist along discontinuities observed in seismic reflectors associated with large-scale flexures or subsidence features. Ground-water seepage gains or losses along the Peace River were quantified by making three seepage runs during periods of: (1) low base flow, (2) high base flow, and (3) high flow. Low and high base-flow seepage runs were performed along a 74-mile length of the Peace River, between Bartow and Nocatee. Maximum losses of 17.3 cubic feet per second (11.2 million gallons per day) were measured along a 3.2-mile reach of the upper Peace River. The high-flow seepage run was conducted to quantify losses in the Peace River channel and floodplain between Bartow and Fort Meade. Seepage losses calculated during high-flow along a 7.2-mile reach of the Peace River, from the Clear Springs Mine bridge to the Mobil Mine bridge, were approximately 10 percent of the river flow, or 118 cubic feet per second. Calculated seepages along the Peace River in Hardee and De Soto Counties were inconclusive, because most seepages were within the range of discharge measurement error. Two continuous aerial thermal infrared imagery surveys were conducted to locate sites of ground-water discharge along the Peace River. Although temperature and hydrologic conditions were ideal to observe spring flow using thermal infrared imaging techniques, no sources of ground-water discharge were identified using this method. Diffuse ground-water seepage may, however, provide significant ground-water discharge.

Florida↗

USGS2015

Estimation of unaltered daily mean streamflow at ungaged streams of New York, excluding Long Island, water years 1961-2010

The lakes, rivers, and streams of New York State provide an essential water resource for the State. The information provided by time series hydrologic data is essential to understanding ways to promote healthy instream ecology and to strengthen the scientific basis for sound water management decision making in New York. The U.S. Geological Survey, in cooperation with The Nature Conservancy and the New York State Energy Research and Development Authority, has developed the New York Streamflow Estimation Tool to estimate a daily mean hydrograph for the period from October 1, 1960, to September 30, 2010, at ungaged locations across the State. The New York Streamflow Estimation Tool produces a complete estimated daily mean time series from which daily flow statistics can be estimated. In addition, the New York Streamflow Estimation Tool provides a means for quantitative flow assessments at ungaged locations that can be used to address the objectives of the Clean Water Act—to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters. The New York Streamflow Estimation Tool uses data from the U.S. Geological Survey streamflow network for selected streamgages in New York (excluding Long Island) and surrounding States with shared hydrologic boundaries, and physical and climate basin characteristics to estimate the natural unaltered streamflow at ungaged stream locations. The unaltered streamflow is representative of flows that are minimally altered by regulation, diversion, or mining, and other anthropogenic activities. With the streamflow network data, flow-duration exceedance probability equations were developed to estimate unaltered streamflow exceedance probabilities at an ungaged location using a methodology that equates streamflow as a percentile from a flow-duration curve for a particular day at a hydrologically similar reference streamgage with streamflow as a percentile from the flow-duration curve for the same day at an ungaged location. The reference streamgage is selected using map correlation, a geostatistical method in which variogram models are developed that correlate streamflow at one streamgage with streamflows at all other locations in the study area. Regression equations used to predict 17 flow-duration exceedance probabilities were developed to estimate the flow-duration curves at ungaged locations for New York using geographic information system-derived basin characteristics. A graphical user interface, with an integrated spreadsheet summary report, has been developed to estimate and display the daily mean streamflows and statistics and to evaluate different water management or water withdrawal scenarios with the estimated monthly data. This package of regression equations, U.S. Geological Survey streamgage data, and spreadsheet application produces an interactive tool to estimate an unaltered daily streamflow hydrograph and streamflow statistics at ungaged sites in New York. Among other uses, the New York Streamflow Estimation Tool can assist water managers with permitting water withdrawals, implementing habitat protection, estimating contaminant loads, or determining the potential affect from chemical spills.

New York↗

USGS2018

Titanium mineral resources in heavy-mineral sands in the Atlantic coastal plain of the southeastern United States

This study examined titanium distribution in the Atlantic Coastal Plain of the southeastern United States; the titanium is found in heavy-mineral sands that include the minerals ilmenite (Fe 2+ TiO 3 ), rutile (TiO 2 ), or leucoxene (an alteration product of ilmenite). Deposits of heavy-mineral sands in ancient and modern coastal plains are a significant feedstock source for the titanium dioxide pigments industry. Currently, two heavy-mineral sands mining and processing operations are active in the southeast United States producing concentrates of ilmenite-leucoxene, rutile, and zircon. The results of this study indicate the potential for similar deposits in many areas of the Atlantic Coastal Plain. This study used the titanium analyses of 3,457 stream sediment samples that were analyzed as part of the U.S. Geological Survey’s National Geochemical Survey program. This data set was analyzed by an integrated spatial modeling technique known as Bayesian hierarchical modeling to map the regional-scale, spatial distribution of titanium concentrations. In particular, clusters of anomalous concentrations of titanium occur: (1) along the Fall Zone, from Virginia to Alabama, where metamorphic and igneous rocks of the Piedmont region contact younger sediments of the Coastal Plain; (2) a paleovalley near the South Carolina and North Carolina border; (3) the upper and middle Atlantic Coastal Plain of North Carolina; (4) the majority of the Atlantic Coastal Plain of Virginia; and (5) barrier islands and stretches of the modern shoreline from South Carolina to northeast Florida. The areas mapped by this study could help mining companies delimit areas for exploration.

Scientific Investigations Report↗

USGS2015

From extreme pH to extreme temperature: An issue in honor of the geochemical contributions of Kirk Nordstrom, USGS hydrogeochemist

This special issue of Applied Geochemistry honors Dr. D. Kirk Nordstrom, and his influential career spent primarily at the U.S. Geological Survey (USGS). This issue does not herald his retirement or other significant career milestone, but serves as a recognition of the impact his work has had on the field of geochemistry in general. This special issue grew from a symposium in Kirk’s honor (affectionately dubbed “Kirkfest”) at the Geological Society of America’s annual meeting in Denver, Colorado, USA, during October 2013. At GSA, 27 talks and 35 posters showed how Kirk’s work has influenced a wide range of current hydrogeochemical research, from geothermal processes to acid mine drainage to geochemical modeling. The breadth of his knowledge and his many contributions to the published literature have left an indelible mark on the field of geochemistry, and this special issue is a tribute to his experience and contributions.

Applied Geochemistry↗

USGS2001

Economic and environmental evaluations of extractable coal resources conducted by the U. S. Geological Survey

The Economic and Environmental Evaluations of Extractable Coal Resources (E4CR) project integrates economic analyses of extractable coal resources with environmental and coal quality considerations in order to better understand the contribution that coal resources can make to help meet the Nation’s future energy needs. The project utilizes coal resource information derived from the recent National Coal Resource Assessment (NCRA), National Oil and Gas Assessment (NOGA), and Coal Availability and Recoverability Studies (CARS) conducted by the U.S. Geological Survey and other State and Federal cooperating agencies. The E4CR evaluations are designed to augment economic models created by the U.S. Geological Survey CARS and NCRA projects and by the Department of Energy/Energy Information Administration (DOE/EIA). E4CR evaluations are conducted on potentially minable coal beds within selected coalfields in the United States. Emphasis is placed on coalfields containing Federally owned coal and within or adjacent to Federal lands, as shown in U.S. Geological Survey Fact Sheets 012-98, 145-99, and 011-00 (U.S. Geological Survey, 1998, 1999, 2000). Other considerations for the selection of study areas include coal quality, potential environmental impact of coal production activities and coal utilization, the potential for coalbed methane development from the coal, and projected potential for future mining. Completion dates for the E4CR studies loosely follow the schedule for analogous NOGA studies to allow for a comparison of different energy resources in similar geographic areas.

Fact Sheet↗

USGS2020

The 3D Elevation Program and energy for the Nation

High-resolution light detection and ranging (lidar) data are used in energy infrastructure siting, design, permitting, construction, and monitoring to promote public safety through the reduction of risks. For example, lidar data are used to identify safe locations for energy infrastructure by analyzing terrain parameters and identifying and evaluating geologic hazards (for example, landslide and fault locations) and their potential public safety effects on the location or design of infrastructure. Increasingly, engineering companies and regulatory agencies are using lidar and other remote sensing techniques as an efficient method to collect accurate, comprehensive data while reducing risks to field personnel. The U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) is collecting lidar data nationwide (interferometric synthetic aperture radar [IfSAR] data in Alaska) to support a wide range of applications, including projects related to energy infrastructure construction and safety. Renewable energy resources, resource mining, and oil and gas resources were identified by the National Enhanced Elevation Assessment as business uses requiring three-dimensional (3D) elevation data. Elevation data are critical in assessing potential sites for energy infrastructure, such as pipelines, refineries and other facilities, to mitigate risks from natural hazards. For example, the Federal Energy Regulatory Commission (FERC), an independent agency that regulates the interstate transmission of electricity, natural gas, and oil, uses enhanced elevation data to conduct National Environmental Policy Act (NEPA) compliance assessments. The acquisition of high-resolution lidar data by the USGS 3DEP initiative helps the FERC and NEPA permit applicants by providing accurate and consistent data for hazards analysis. The use of these data accelerates the application and review process and avoids the much higher costs of acquiring elevation data along proposed energy facility locations and pipeline corridors.

Fact Sheet↗

USGS1986

Water-use data-collection programs and regional data base of the Great Lakes-St. Lawrence River Basin states and provinces; a comparison of withdrawal-data programs by water-use category and by state and province

As a result of the Great Lakes Charter (signed by Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Ontario, Pennsylvania, Quebec, and Wisconsin), the Geological Survey worked with a committee of the Council of Great Lakes Governors to document the water use data collection programs in the Basin. These programs are described for public water supply; supplies for domestic, irrigation, agricultural, commercial, industrial, and mining uses; and supplies for powerplants. Frequency of collection, trigger levels, storage methods, and legislative framework are described. A regional water use data base was designed to store withdrawal, diversion, and consumptive use data on a drainage basin basis. The data base will be used to decide the advisability of proposed water diversion and consumptive use projects as part of a water management strategy. Data base formats, requirements, and methods of data transmittal from each area are described. Methods for acquiring missing data are suggested. The data base will be housed by the Great Lakes Commission, Ann Arbor, Michigan. (USGS)

Open-File Report↗

USGS1997

A120 yr record of widespread contamination from mining of the Iberian pyrite belt

A metal-enriched seawater plume entering the western Mediterranean Sea through the Strait of Gibraltar originates 300 km to the west in the Rio Tinto estuary of southwestern Spain. Mining of Rio Tinto ore, one of the largest metal-rich sulfide deposits in the world, started well before Roman times. Contemporary Rio Tinto waters draining the region are highly acidic (pH 2.5) with dissolved cadmium, zinc, and copper concentrations 10 5 −10 6 times higher than in uncontaminated surface water of the Gulf of Cadiz. Two dated sediment cores from the Spanish continental shelf show that metal inputs to the region increased with the onset of intensive mining activities during the second half of the 19th century. Although the impact of mining may have decreased over the past few decades, the Tinto river and estuary remain highly contaminated.

Geology↗

USGS1976

Compositional variations in wolframite from the Hamme (Tungsten Queen) mine, North Carolina

A microprobe study of wolframite from the Tungsten Queen mine, Hamme district, North Carolina, proves it to be almost pure huebnerite. Concentric zoning, which shows up as light-brown and dark-brown bands, indicates small variations in the content of FeO. There is no apparent correlation between the small variations in the composition of the wolframite and its position in the mine. The Fe/Mn ratio of the wolframite is not indicative of the temperature of crystallization.

North Carolina↗

USGS1968

Geology and lode gold deposits of the Nuka Bay area, Kenai Peninsula, Alaska

Nuka Bay is a deep, T-shaped fiord on the southeast coast of the Kenai Peninsula approximately 60 miles southwest of the port of Seward. Gold-bearing quartz veins were discovered in the area in 1918, and between 1920 and 1940 several small mines were in operation around the North and West Arms of the bay. Estimated total production may have been as much as $164,000. Bedrock in the Nuka Bay area is a thick Cretaceous section of interbedded slate and graywacke that has been regionally deformed into a series of relatively open, but overturned, folds plunging at low angler to the north-northeast. Except at the folds, bedding and foliation (slaty cleavage) are parallel and dip steeply to the northwest. Small granodiorite dikes fill tensional cross joints in the folded sediments, and a few granodiorite sills are intruded along bedding and foliation planes. Quartz veins are abundant throughout the region, but contain significant amounts of gold only in a relatively small area, 8 miles long and 6 miles wide, around North and West Arms. The veins are generally less than 5 feet wide and 300 feet long and consist chiefly of massive white quartz. Arsenopyrite with minor amounts of other sulfide and native gold occurs as irregular masses and pods in the quartz. The larger and more productive veins dip steeply and strike east-west, almost normal to the regional structure, and appear to be confined to competent graywacke beds or dikes. Random channel sampling of the quartz veins indicates gold values as high as 9 ounces per ton across zones as wide as 2 feet. A study of the stream sediments throughout the area disclosed several drainages with detectable gold; one, Babcock Creek, contained 0.5 ppm gold, the others from 0.02 to 0.07 ppm. No base metal anomalies were detected. The area appears to warrant further investigation as a potential producer of small amounts of gold. Diligent smell-scale mining may be economically feasible.

Alaska↗

USGS2004

Geologic history of natural coal-bed fires, Powder River basin, USA

Coal-bed fires ignited by natural processes have baked and fused overlying sediments to form clinker, a hard red or varicolored rock, through much of the northern Great Plains of the United States (USA). The gently dipping coal beds in the region burn when regional downwasting brings them above the local water table. The resulting clinker forms a rim along the exposed edge of the coal bed in an ongoing process through geologic time. The resistant clinker is left capping buttes and ridges after the softer unbaked strata erode away. Clinker outcrops cover more than 4100 km2 in the Powder River basin (PRB), which lies in Wyoming (WY) and Montana (MT). The clinker in place records tens of billions of tons of coal that have burned, releasing gases into the atmosphere. The amount of clinker that has eroded away was at least an order of magnitude greater than the clinker that remains in place. Fission-track and uranium-thorium/ helium ages of detrital zircon crystals in clinker, and paleomagnetic ages of clinker, show that coal beds have burned naturally during at least the past 4 million years (Ma). The oldest in-place clinker that has been dated, collected from a high, isolated, clinker-capped ridge, has a fission track age of 2.8??0.6 Ma. Evidence of erosion and downcutting is also preserved by clinker clasts in gravel terraces. One clinker boulder in a terrace 360 m above the Yellowstone River has a fission track age of 4.0??0.7 Ma. Coal-bed fires are caused by lightning, wildfires, spontaneous combustion, or human activity on coal outcrops and in mines. Miners, government agencies, and ranchers have extinguished thousands of coal bed fires, but natural ignition continues where fresh coal has access to air. At any given time, hundreds of fires, mostly small, are burning. In the Powder River basin, the total amount of coal burned by natural fires in the last 2 Ma is one to two orders of magnitude greater than the total amount of coal removed by mining in the past century. However, current annual rates of coal mining are three to four orders of magnitude greater than estimated prehistoric annual rates of coal consumption by natural fires. ?? 2004 Published by Elsevier B.V.

International Journal of Coal Geology↗

USGS1952

Magnetite deposits and magnetic anomalies of the Brandy Brook and Silver Pond belts, St. Lawrence County, New York

This report sets forth the geology and economic possibilities of the Brandy Brook and Silver Pond belts of magnetic anomalies, Cranberry Lake quadrangle, St. Lawrence County, northwestern New York. each belt contains a known magnetite deposit, partly explored through diamond drilling by the U.S. Bureau of Mines. The Brandy Brook Northwest deposit is a body of low-grade to medium-grade ore, possibly of lathlike shape. The Silver Pond deposit has no commercial interest at the moment. One of more promising magnetic anomalies remain to be tested by drilling.

New York↗

USGS2012

Simulated flow of groundwater and brine from a flooded salt mine in Livingston County, New York, and effects of remedial pumping on an overlying aquifer

Two ceiling collapses in the Retsof salt mine near Geneseo in upstate New York in spring 1994 resulted in the upward propagation of two columns of rubble through 600 feet of overlying shale and carbonate bedrock. This upward propagation formed a hydraulic connection between the lower confined aquifer (LCA) and the mine and allowed water from the aquifer and bedrock fracture zones that intersected the rubble columns to flow into the mine at a rate of 18,000 gallons per minute (gal/min) . All salt mining ceased in September 1995, and the mine was completely flooded by January 1996. The flow of water from the lower confined aquifer into the mine caused widespread drawdowns, and water levels in the aquifer declined by as much as 400 feet near the collapse area and by more than 50 feet at wells 7 miles to the north and south. Within 3 to 4 weeks of the collapses, water levels in about a dozen domestic and industrial wells had declined severely, and some wells went dry. Water levels in at least 58 wells in the lower and middle confined aquifers were affected by mine flooding. Groundwater in the upper unconfined aquifer and surface water in streams were unaffected by water-level drawdown, but channels of the Genesee River and Beards Creek were altered by land subsidence related to the mine collapse. Water levels recovered from 1996 through 2006, but the mine is now filled with about 15 billion gallons of saturated halite brine. The weight of the overlying rock and sediment is expected to cause the salt beds to deform and fill the mine cavity during the next several hundred years; this in turn could displace as much as 80 percent of the brine and cause it to move upward through the rubble chimneys, rendering the LCA unusable as a source of water supply. Saline water was detected in the LCA in 2002 but was found to be derived primarily from fractures in the limestone and shale units between the mine and the LCA, rather than from the mine. In September 2006, the mine company began a brine-mitigation project that entailed pumping five wells finished in limestone and shale units within the collapse areas to alter the flow gradient and thereby prevent further movement of brine and saline water into the LCA. The pumped brine was routed to an onsite desalination plant. At the same time, the U.S. Geological Survey (USGS) began a study in cooperation with the New York State Office of the Attorney General to construct numerical models to analyze the groundwater chemistry and delineate the directions of flow. Specific objectives of the study were to: * Assess the sources of salinity within the collapse area and identify the factors that control the movement and mixing of freshwater, saline waters from fracture zones, and brine; * Evaluate the likelihood that the pumping will induce anhydrite dissolution and lead to continued land subsidence; * Construct variable-density groundwater flow models to predict the effect of remedial pumping on salinity within the LCA; * Evaluate the effectiveness of remedial pumping in preventing the movement of saline water into the LCA; and * Predict the extent of brine migration 8 years after a hypothetical shutdown of all pumping in 2008. This report (1) summarizes the hydrogeologic setting and effects of mine flooding, (2) describes the geochemical and variable-density model simulations and their principal results, (3) discusses the implications of (a) continued pumping and desalination to protect the LCA and (b) a full shutdown of pumping after 2008, and (4) suggests further research that could lead to refinement of model predictions. Additional information may be found in Yager and others (2001 and 2009). These reports can be accessed at http://pubs.usgs.gov/pp/pp1611/ and http://pubs.usgs.gov/pp/pp1767/, respectively. A summary of simulation results can be accessed at http://ny.water.usgs.gov/projects/Coram/seawat/seawat.html.

New York↗