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At least 1,153 records · Page 64Linked to original sources
USGS2014

Hematite-bearing materials surrounding Candor Mensa in Candor Chasma, Mars: Implications for hematite origin and post-emplacement modification

The Valles Marineris canyon system on Mars is of enduring scientific interest in part due to the presence of interior mounds that contain extensive layering and water-altered minerals, such as crystalline gray hematite and hydrated sulfates. The presence of hematite and hydrated sulfate minerals is important because their host rock lithologies provide information about past environments that may have supported liquid water and may have been habitable. This work further defines the association and relationship between hematite-bearing materials and low albedo (presumably aeolian) deposits and layered materials, identifies physical characteristics that are strongly correlated with the presence of hematite, and refines hypotheses for the origin and post-emplacement modification (including transport) of these hematite-bearing and associated materials. There are only three regions surrounding Candor Mensa where hematite has been identified, even though morphologic properties are similar throughout the entire mensa. Three possible explanations for why hematite is only exposed in these regions include: (1) the topographic structure of the mensa walls concentrates hematite at the base of the layered deposits, influencing the ability to detect hematite from orbit; (2) the presence of differing amounts of “dark mantling material” and hematite-free erosional sediment; (3) the potential fracturing of the mensa and the influence of these structures on fluid flow and subsequent digenesis. The observations of hematite-bearing materials in this work support the hypothesis that hematite is eroding from a unit in the Candor Mensa interior layered deposits (ILD) and is being concentrated as a lag deposit adjacent to the lower layers of Candor Mensa and at the base in the form of dark aeolian material. Due to the similar geologic context associated with hematite-bearing and ILD materials throughout the Valles Marineris canyon system, the insight gained from studying these materials surrounding Candor Mensa can likely be applicable to similar layered deposits throughout Valles Marineris.

Icarus↗
USGS1997

Environmental geochemistry of shale-hosted Ag-Pb-Zn massive sulfide deposits in northwest Alaska: Natural background concentrations of metals in water from mineralized areas

Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed (unmined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate reeks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg 1-1 Al, 270 mg 1-1 Fe, 8 ??1-1 Cd, 10 ??1-1 Pb, and 2600 ??1-1 Zn, with As up to 26 ??g1-1. Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

Applied Geochemistry↗
USGS1999

Using imaging spectroscopy to map acidic mine waste

The process of pyrite oxidation at the surface of mine waste may produce acidic water that is gradually neutralized as it drains away from the waste, depositing different Fe-bearing secondary minerals in roughly concentric zones that emanate from mine-waste piles. These Fe-bearing minerals are indicators of the geochemical conditions under which they form. Airborne and orbital imaging spectrometers can be used to map these mineral zones because each of these Fe-bearing secondary minerals is spectrally unique. In this way, imaging spectroscopy can be used to rapidly screen entire mining districts for potential sources of surface acid drainage and to detect acid producing minerals in mine waste or unmined rock outcrops. Spectral data from the AVIRIS instrument were used to evaluate mine waste at the California Gulch Superfund Site near Leadville, CO. Laboratory leach tests of surface samples show that leachate pH is most acidic and metals most mobile in samples from the inner jarosite zone and that leachate pH is near-neutral and metals least mobile in samples from the outer goethite zone.

Environmental Science & Technology↗
USGS2006

Mineralogical characterization of protolith and fault rocks from the SAFOD Main Hole

Washed cuttings provide a continuous record of the rocks encountered during drilling of the main hole of the San Andreas Fault Observatory at Depth (SAFOD). Both protolith and fault rocks exhibit a wide variety of mineral assemblages that reflect variations in some combination of lithology, P-T conditions, deformation mechanisms, and fluid composition and abundance. Regions of distinct neomineralization bounded by faults may record alteration associated with fluid reservoirs confined by faults. In addition, both smectites occurring as mixed-layer phases and serpentine minerals are found in association with active strands of the San Andreas Fault that were intersected during drilling, although their rheological influence is not yet fully known. Faults containing these mineralogical phases are prime candidates for continuous coring during Phase 3 of SAFOD drilling in the summer of 2007. Copyright 2006 by the American Geophysical Union.

Geophysical Research Letters↗
USGS2019

Variability in results from mineralogical and organic geochemical interlaboratory testing of U. S. Geological Survey shale reference materials

The expansion of unconventional petroleum resource exploration and production in the United States has led to an increase in source rock characterization efforts, particularly related to bulk organic and mineralogical properties. To support the analytical and research needs of industry and academia, as well as internal work, the U.S. Geological Survey (USGS) has collected and prepared shale geochemical reference materials (GRMs) from several major shale petroleum systems in the U.S. The sources of these materials are the Late Cretaceous Boquillas (lower Eagle Ford-equivalent) Formation (roadcut near Del Rio, TX), Late Cretaceous Mancos Shale (outcrop near Delta, CO), Devonian–Mississippian Woodford Shale (outcrop near Ardmore, OK), Late Cretaceous Niobrara Formation (quarry near Lyons, CO), Middle Devonian Marcellus Shale (creek bed in LeRoy, NY), and Eocene Mahogany zone oil shale of the Green River Formation (oil shale mine near Rifle, CO). Of particular interest in the development of these GRMs has been the examination of variability between laboratories and specific methods or instruments in commonly made measurements, including major- and trace-element concentrations, X-ray diffraction (XRD) mineralogy, total organic carbon (TOC) content, and programmed pyrolysis (PP) parameters. For the component concentrations and parameters we measured, the techniques and instrument types included: (1) elemental analysis by X-ray fluorescence, inductively coupled plasma mass spectrometry, and instrumental neutron activation analysis; (2) XRD mineralogy with various preparatory methods (spray drying or micronizing with or without internal standard); (3) TOC by combustion with infrared detection after carbonate removal or the PP approach; (4) PP by Rock-Eval 2 or more recently developed instruments (Rock-Eval 6, Source Rock Analyzer or SRA, and Hydrocarbon Analyzer With Kinetics or HAWK). Overall, the results showed that the selected shales cover a wide range of source rock organic and mineralogical properties. Major- and trace-element chemistry results showed low heterogeneity consistent with other USGS GRMs. Comparison of TOC results showed coefficients of variation (COV) of around 5% and the most consistent organic geochemical results between different laboratories and methods. Arguably the most relevant PP measurement, S2 or kerogen hydrocarbon-generating potential (mg-HC/g-rock), showed a somewhat wider range of variability than TOC (COV ~10%), but was consistent between the three modern instruments and the industry-standard Rock-Eval 2. Major phase mineralogy (mineral concentrations ≥10 wt. %, organic-free basis) were comparable between laboratories, but variability in minor phase identification and quantification was observed. Utilization of these shale GRMs as quality control samples and testing materials is expected to help support analytical and experimental efforts in the continued development of unconventional petroleum resources.

Colorado, Texas, Oklahoma↗
USGS1947

The sangdong tungsten deposit, southern Korea

The Sangdong deposit consists of metamorphosed lenticular beds in a sequence of gently dipping argillaceous sedimentary rocks. It is believed that scheelite mineralization was simultaneous with metamorphism, followed by deposition of wolframite during a later hydrothermal phase. The reserve of ore is estimated to be 3,000,000 tons, containing 51,000 tons of WO (sub 3.)

southern Korea↗
USGS1984

Uranium mineralization in response to regional metamorphism at Lilljuthatten, Sweden

Analyses of six mineralized and five nonmineralized whole-rock drill core samples from the uranium deposit at Lilljuthatten yield a lead-lead isochron age of 420 + or - 1 m.y. This age corresponds to the last stage of the Caledonian Orogeny. None of the isotopic systems examined have completely retained the intrusive age of the Olden Granite, but data for several systems suggest an age of approximately 1,650 m.y. Indications that Caledonian hydrothermal activity strongly affected most of the Olden Granite. A model for the genesis of the ore deposit is proposed as follows: (1) derivation of a highly evolved granite by partial melting of crustal materials about 1,650 m.y. ago; (2) pervasive hydrothermal alteration and fracturing of the granite in response to the Caledonian Orogeny approximately 420 m.y. ago; (3) mobilization of uranium and lead in response to circulation of heated fluids; (4) precipitation of these elements in open fractures; and (5) recent modification of the Caledonian uranium distribution as a result of exposure to near-surface conditions.

Economic Geology↗
USGS1946

Preliminary report on the stratigraphy and structure of the Kurupa, Colville, and Oolamnagavik Rivers, Alaska

U. S. Geological Survey Party No. 4 covered the area between 68° 30' and 69° 08' N. latitude and between 154° and 155°20' W. longitude during the period May 18 to September 2. Traverses were confined mainly to the valleys of the Kurupa, Colville, and Oolamnagavik Rivers inasmuch as very little rock is exposed in the interstream areas. This report is limited to the Colville River valley area between the Kura and Killik Rivers, and to a stratigraphic section exposed. on the Kurupa 7-12 miles south of the Colville. A final report will be prepared by April 1, 1947, on the total area and will include discussions of the stratigraphy and structure of Upper Cretaceous formations A through D on the Oolamnagavik and Kurupa, the stratigraphy of Formation D on the Colville, and the Lower Cretaceous and Triassic rocks. Separation and identification of heavy minerals from the sandstones and conglomerates, binocular and petrographic microscope examinations of specimens, identification of megafossils, and separation and identification of microfossils, if any, will be undertaken. Detailed examination of all aerial photos will be made to trace out structures and formations in the adjacent areas to the east, north, and west. It seems probable that close correlation between this area, the Killik River area, and Maybe Creek area will be possible by extrapolating field and aerial photo data. It is possible also to trace structures and some formation westward from the Kurupa River.

Alaska↗
USGS1993

International strategic minerals inventory summary report; niobium (columbium) and tantalum

Major world resources of niobium and tantalum are described in this summary report of information in the International Strategic Minerals Inventory (ISMI). ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, the United Kingdom, and the United States of America. Part I of this report presents an overview of the resources and potential supply of niobium and tantalum based on inventory information; Part II contains tables of both geologic and mineral-resource information and includes production data collected by ISMI participants. Niobium is used principally as an alloying element in special steels and superalloys, and tantalum is used mainly in electronics. Minerals in the columbite-tantalite series are principal ore minerals of niobium and tantalum. Pyrochlore is a principal source of niobium. These minerals are found in carbonatite, certain rocks in alkaline igneous complexes, pegmatite, and placer deposits. ISMI estimates show that there are over 7 million metric tons of niobium and almost 0.5 million metric tons of tantalum in known deposits, outside of China and the former Soviet Union, for which reliable estimates have been made. Brazilian deposits, followed by Canadian deposits, contain by far the largest source of niobium. Tantalum production is spread widely among several countries, and Brazil and Canada are the most significant of these producers. Brazil's position is further strengthened by potential byproduct columbite from tin mining. Present economically exploitable resources of niobium appear to be sufficient for the near future, but Brazil will continue to be the predominant world supplier of ferrocolumbium. Tantalum, a byproduct of tin production, has been captive to the fluctuations of that market, but resources in pegmatite in Canada and Australia make it likely that future increases in the present modest demand will be met.

Circular↗
USGS1997

Geology and resource assessment of Costa Rica at 1:500,000 scale; a digital representation of maps of the U.S. Geological Survey's 1987 folio I-1865

This CD-ROM contains digital versions of the geology and resource assessment maps of Costa Rica originally published in USGS Folio I-1865 (U.S. Geological Survey, the Direccion General de Geologia, Minas e Hidrocarburos, and the Universidad de Costa Rica, 1987) at a scale of 1:500,000. The following layers are available on the CD-ROM: geology and faults; favorable domains for selected deposit types; Bouguer gravity data; isostatic gravity contours; mineral deposits, prospects, and occurrences; and rock geochemistry sample points. For DOS users, the CD-ROM contains MAPPER, a user-friendly map display program. Some of the maps are also provided in the following additional formats on the CD-ROM: (1) ArcView 1 and 3, (2) ARC/INFO 6.1.2 Export, (3) Digital Line Graph (DLG) Optional, and (4) Drawing Exchange File (DXF.)

Data Series↗
USGS2009

Geochemical database for igneous rocks of the ancestral Cascades Arc— Southern segment, California and Nevada

Volcanic rocks that form the southern segment of the Cascades magmatic arc are an important manifestation of Cenozoic subduction and associated magmatism in western North America. Until recently, these rocks had been little studied and no systematic compilation of existing composition data had been assembled. This report is a compilation of all available chemical data for igneous rocks that constitute the southern segment of the ancestral Cascades magmatic arc and complement a previously completed companion compilation that pertains to rocks that constitute the northern segment of the arc. Data for more than 2,000 samples from a diversity of sources were identified and incorporated in the database. The association between these igneous rocks and spatially and temporally associated mineral deposits is well established and suggests a probable genetic relationship. The ultimate goal of the related research is an evaluation of the time-space-compositional evolution of magmatism associated with the southern Cascades arc segment and identification of genetic associations between magmatism and mineral deposits in this region.

California, Nevada↗
USGS2001

Metal loading assessment of a small mountainous sub-basin characterized by acid drainage -- Prospect Gulch, upper Animas River watershed, Colorado

strongly affected by natural acidity from pyrite weathering. Metal content in the water column is a composite of multiple sources affected by hydrologic, geologic, climatic, and anthropogenic conditions. Identifying sources of metals from various drainage areas was determined using a tracer injection approach and synoptic sampling during low flow conditions on September 29, 1999 to determine loads. The tracer data was interpreted in conjunction with detailed geologic mapping, topographic profiling, geochemical characterization, and the occurrence and distribution of trace metals to identify sources of ground-water inflows. For this highly mineralized sub-basin, we demonstrate that SO4, Al, and Fe load contributions from drainage areas that have experienced historical mining?although substantial?are relatively insignificant in comparison with SO4, Al, and Fe loads from areas experiencing natural weathering of highlyaltered, pyritic rocks. Regional weathering of acid-sulfate mineral assemblages produces moderately low pH waters elevated in SO4, Al, and Fe; but generally lacking in Cu, Cd, Ni, and Pb. Samples impacted by mining are also characterized by low pH and large concentrations of SO4, Al, and Fe; but contained elevated dissolved metals from ore-bearing vein minerals such as Cu, Zn, Cd, Ni, and Pb. Occurrences of dissolved trace metals were helpful in identifying ground-water sources and flow paths. For example, cadmium was greatest in inflows associated with drainage from inactive mine sites and absent in inflows that were unaffected by past mining activities and thus served as an important indicator of mining contamination for this environmental setting. The most heavily mine-impacted reach (PG153 to PG800), contributed 8% of the discharge, and 11%, 9%, and 12% of the total SO4, Al, and Fe loads in Prospect Gulch. The same reach yielded 59% and 37% of the total Cu and Zn loads for the subbasin. In contrast, the naturally acidic inflows from the Red Chemotroph iron spring yielded 39% of the discharge and 54%, 73%, and 87% of the SO4, Al, and Fe loads; but only 4% of the total Cu and 30% of the total Zn loads in Prospect Gulch. Base flow from the Prospect Gulch sub-basin contributes about 4.8 percent of the total discharge at the mouth of Cement Creek; compared with sampled instream loads of 1.8%, 8.8%, 15.9%, 28%, and 8.6% for SO4, Al, Fe, Cu and Zn, respectively. Water-shed scale remediation efforts targeted at reducing loads of SO4, Al, and Fe at inactive mine sites are likely to fail because the major sources of these constituents in Prospect Gulch are predominantly discharged from natural sources. Remediation goals aimed at reducing acidity and loads of Cu and other base metals, may succeed, however, because changes in pH and loads are disproportionately greater than increases in discharge over the same reach, and a substantial fraction of the metal loading is from mining-impacted reaches. Whether remediation of abandoned mines in Prospect Gulch can be successful depends on how goals are defined?that is, whether the objective is to reduce loads of SO4, Al, and Fe; or whether loads of Cu and other base metals and pH are targeted.

Open-File Report↗
USGS1973

Summary of seismic activity and its relation to geology and mining in the Sunnyside mining district, Carbon and Emery Counties, Utah, during 1967-1970

In the Sunnyside mining district, Utah, coal is mined under thick and variable overburden which is locally weakened by faults and other structural discontinuities. Stress changes and local stress concentrations produced by mining under these conditions often cause sudden and violent ruptures in the coal and surrounding rock mass. The strain energy released by this type of failure, which can produce shock waves and may discharge coal and rock with explosive force, is often a serious threat to life and property. These releases of strain energy are called bumps or bounces by miners if they occur in the coal, and rock bursts if they occur in the surrounding rock mass. Many of these releases are so violent that they generate seismic waves that can be felt, or at least detected by seismic instruments, miles from the site of the rupture, whereas others are smaller and can be detected only by those sensitive seismic instruments within a few thousand feet of the site of the rupture. In 1969 and 1970, about 27,000 and about 15,000 earth tremors, respectively, were recorded by the five-station seismic monitoring network that is located at the surface and encompasses most of the mine workings in the district. Of these totals, 512 and 524 earth tremors, respectively, were of sufficient magnitude (greater than 1. 5 on the Richter scale) so that the hypocenters could be accurately located. In 1968 about 20,000 tremors were recorded, with 281 large enough to plot, but in 1967 over 50,000 were recorded, of which 540 were plotted. In this report we discuss the way in which seismic activity, geology, and mining are related or seem to be related for the period 1967 through 1970, with emphasis on the period 1969-70. We also suggest certain mining procedures which, based on studies during the period, might increase the safety and efficiency of mining operations in the Sunnyside district. A complete tabulation of the larger magnitude earth tremors which occurred during 1969-70 and descriptions of how they relate to mining are given in the appendix. Similar tabulations and descriptions for 1967 and 1968 are available in earlier reports (Barnes and others, 1969; Dunrud and others, 1970).

Open-File Report↗
USGS1974

Economic geology of the Isla de Mona Quadrangle, Puerto Rico

Limiting this tableland In the northern part of Isla de Mona are sheer sea cliffs chiefly exposing the Isla de Mona Dolomite. Around the southern part of the island are Irregular cliffs and steep slopes that chiefly expose the Lirio Limestone. The structure of Isla de Mona consists of two gentle complex folds a broad anticline that trends and plunges gently south-southeast through the central and western parts of Isla de Mona, and a parallel syncline through-the eastern part of the Island that also has a chiefly south-southeast plunge. A near-vertical fault that strikes northwest, then north from the central part to the north coast of Isla de Mona displaces bedrock of the eastern block downward about 10 m. Many caves, including one cave system more than 100,000 m2 in total area, are localized in the lower 10 m of the Lirio Limestone, adjacent to the cliffs peripheral to the upland surface, and numerous small caves occur higher in the Lirio. A few small caves also are found In the Isla de Mona Dolomite. However, the total floor area of all caves on Isla de Mona probably is less than 1 percent of the area of the Island. Almost all caves on Isla de Mona contain phosphorite, which was mined extensively during the late 19th and early 20th centuries. Phosphorite accumulation locally may have exceeded 3.5 m in thickness, but probably averaged less than 1.5 m thick. A fair estimate of original reserves of phosphorite in 12 surveyed caves is about 151,000 m3 of which about 125,500 m3 probably has been removed in mining. Original reserves in the entire island are estimated to have been in the range 158,000 to 235,500 m3. Converted to metric tons, remaining reserves of cave phosphorite probably are considerably less than 50,000. The very pure limestone and calcitic dolomite that form the bedrock of Isla de Mona are abundant industrial-mineral resources. In addition, these carbonate rocks and the beach deposits are sources of construction materials for some classes of engineering works. The structure of Isla de Mona suggests some possibility of favorable zones for accumulation of oil and gas, but no source rocks are known, and there are no confirmed reports of oil and gas from any nearby area. Known supplies of fresh water on Isla de Mona are very small, but wells dug in coastal lowlands or drilled In the upland surface might yield moderate quantities of groundwater.

Open-File Report↗
USGS1977

Geohydrology of the Great Bend Prairie, south-central Kansas

Unconsolidated deposits of Pliocene and Pleistocene age comprise the principal aquifer in the Great Bend Prairie. Forty-five million acre-feet of ground water are estimated to be in storage in these deposits. Only about 60 percent of this amount may be usable owing to an insufficient saturated thickness and to high mineralization of water locally. Yields to irrigation wells are commonly between 500 and 1,000 gal/min, and yields of as much as 2,000 gal/min may be available in localities where the saturated thickness is greater than 100 feet. In 1940, there were about 30 municipal and industrial wells and 50 irrigation wells in the area. In 1973, there were about 200 municipal and industrial wells and 950 irrigation wells; and in 1974, about 1,160 irrigation wells. Annual withdrawals of ground water by wells increased from about 5,000 acre-feet in 1940 to about 140,000 acre-feet in 1974. The steadily increasing withdrawal rate has not produced long-term declines of water levels that may be distinguished from the effects of climatic changes. Significant additional development for irrigation that could cause ground-water withdrawal to exceed long-term recharge and result in water-level declines is anticipated in some areas. The average annual recharge rate to ground water from precipitation is estimated to be about 2 inches. The chemical quality of ground water from unconsolidated deposits in the western half of the area is generally suitable for most uses. The chemical quality of water in the eastern half may be unsuitable locally for most purposes as a result of upward leakage of highly mineral-ized water from underlying Permian rocks. Locally, wells in rocks of Early Permian or Early Cretaceous age may yield from about 10 to 100 gal/min. However, the water from these wells generally contains more than 1,000 mg/L (milligrams per liter) of dissolved solids and more than 500 mg/L of chloride and sulfate.

Kansas↗
USGS1978

U.S. Geological Survey offshore program of resource and geo-environmental studies and topical investigations, Pacific-Arctic region

The Geological Survey's marine geology investigations in the Pacific-Arctic area are presented in this report in the context of the underlying socio-economic problem of expanding the domestic production of oil and gas and other mineral and hard- and soft-rock resources while maintaining acceptable standards in the marine environment. The primary mission of the Survey 's Pacific-Arctic Branch of Marine Geology is to provide scientifically interpreted information about the (1) resource potential, (2) geo-environmental setting, and (3) overall geologic characteristics of the continental margins (that is, the continental shelf, slope and rise) and adjacent deeper water and shallower coastal areas off California, Oregon, Washington, Alaska and Hawaii and also, where it is of interest to the U.S. Government, more remote deep-sea areas of the Pacific-Arctic realm.

Open-File Report↗