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Sample records for ore deposits

  1. Evolution of ore deposits on terrestrial planets

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1991-01-01

    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars

  2. Oil shales, evaporites and ore deposits

    NASA Astrophysics Data System (ADS)

    Eugster, Hans P.

    1985-03-01

    The relationships between oil shales, evaporites and sedimentary ore deposits can be classified in terms of stratigraphic and geochemical coherence. Oil shale and black shale deposition commonly follows continental red beds and is in turn followed by evaporite deposition. This transgressive-regressive sequence represents an orderly succession of depositional environments in space and time and results in stratigraphic coherence. The amount of organic carbon of a sediment depends on productivity and preservation, both of which are enhanced by saline environments. Work on Great Salt Lake. Utah, allows us to estimate that only 5% of TOC originally deposited is preserved. Inorganic carbonate production is similar to TOC production, but preservation is much higher. Oil shales and black shales commonly are enriched in heavy metals through scavenging by biogenic particles and complexation by organic matter. Ore deposits are formed from such rocks through secondary enrichment processes, establishing a geochemical coherence between oil shales and ore deposits. The Permian Kupferschiefer of N. Europe is used as an example to define a Kupferschiefer type (KST) deposit. Here oxygenated brines in contact with red beds become acidified through mineral precipitation and acquire metals by dissolving oxide coatings. Oxidation of the black shale leads to further acid production and metal acquisition and eventually to sulfide deposition along a reducing front. In order to form ore bodies, the stratigraphic coherence of the red bed-black shale-evaporite succession must be joined by the geochemical coherence of the ore body-evaporite-black shale association. The Cretaceous Cu-Zn deposits of Angola, the Zambian Copperbelt as well as the Creta, Oklahoma, deposits are other KST examples. In the Zambian Copperbelt, evaporites are indicated by the carbonate lenticles thought to be pseudomorphs after gypsum-anhydrite nodules. MVT deposits are also deposited by acid brines, but at more

  3. The physical hydrogeology of ore deposits

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Appold, M.S.

    2012-01-01

    Hydrothermal ore deposits represent a convergence of fluid flow, thermal energy, and solute flux that is hydrogeologically unusual. From the hydrogeologic perspective, hydrothermal ore deposition represents a complex coupled-flow problem—sufficiently complex that physically rigorous description of the coupled thermal (T), hydraulic (H), mechanical (M), and chemical (C) processes (THMC modeling) continues to challenge our computational ability. Though research into these coupled behaviors has found only a limited subset to be quantitatively tractable, it has yielded valuable insights into the workings of hydrothermal systems in a wide range of geologic environments including sedimentary, metamorphic, and magmatic. Examples of these insights include the quantification of likely driving mechanisms, rates and paths of fluid flow, ore-mineral precipitation mechanisms, longevity of hydrothermal systems, mechanisms by which hydrothermal fluids acquire their temperature and composition, and the controlling influence of permeability and other rock properties on hydrothermal fluid behavior. In this communication we review some of the fundamental theory needed to characterize the physical hydrogeology of hydrothermal systems and discuss how this theory has been applied in studies of Mississippi Valley-type, tabular uranium, porphyry, epithermal, and mid-ocean ridge ore-forming systems. A key limitation in the computational state-of-the-art is the inability to describe fluid flow and transport fully in the many ore systems that show evidence of repeated shear or tensional failure with associated dynamic variations in permeability. However, we discuss global-scale compilations that suggest some numerical constraints on both mean and dynamically enhanced crustal permeability. Principles of physical hydrogeology can be powerful tools for investigating hydrothermal ore formation and are becoming increasingly accessible with ongoing advances in modeling software.

  4. Proterozoic geology and ore deposits of Arizona

    USGS Publications Warehouse

    Karlstrom, Karl E.

    1991-01-01

    Proterozoic rocks in Arizona have been the focus of interest for geologists since the late 1800's. Early investigations, led by the U.S. Geological Survey, focused on the extensive ore deposits hosted by Proterozoic rocks. By the 1960's, these studies, combined with theses from academic institutions and the efforts of the Arizona Geological Survey, had produced a rich data base of geologic maps, primarily of the central part of the Transition Zone. The chronological significance of these maps became much better known with the application of U-Pb geochronology by L.Y. Silver and his students starting in the 1960's. The 1970's and early 1980's were marked by numerous contributions from Masters and Ph.D students at a variety of academic institutions, and continued work by the U.S. Geological Survey. Interest in ore deposits persisted and there was an increasing interest in interpretation of the tectonic history of Proterozoic rocks in terms of plate tectonic models, as summarized in papers by Phillip Anderson, Ed DeWitt, Clay Conway, Paul Lindberg, and J.L Anderson in the 1989 Arizona Geological Society Digest 17: "Geologic Evolution of Arizona". The present volume: "Proterozoic Geology and Ore deposits of Arizona" builds upon A.G.S. Digest 17, and presents the results of geologic investigations from the latter part of the 1980's. A number of the papers are condensed versions of MS theses done by students at Northern Arizona University. These papers are based upon 1:10,000 mapping and structural analysis of several areas in Arizona. The geologic maps from each of these studies are available separately as part of the Arizona Geological Survey Contributed Map Series. These detailed maps, plus the continuing mapping efforts of the U.S.G.S. and students at other academic institutions, form an ever improving data base for continuing attempts to understand the Proterozoic geology and ore deposits of Arizona

  5. Physical-chemical conditions of ore deposition

    USGS Publications Warehouse

    Barton, P.B.

    1981-01-01

    Ore deposits form under a wide range of physical and chemical conditions, but those precipitating from hot, aqueous fluids-i.e. the hydrothermal deposits-form generally below 700??C and at pressures of only 1 or 2 kbar or less. Natural aqueous fluids in rocks may extract metal and sulfur from a variety of rock types or may acquire them as a residual heritage from a crystallizing silicate magma. Ore-forming hydrothermal fluids never appear as hot springs (except in deep, submarine situations) because they boil, mix with surface waters, and cool, thereby losing their ore-bearing ability before reaching the surface. Mineral systems function as chemical buffers and indicators just as buffers and indicators function in a chemical laboratory. By reading the record written in the buffer/indicator assemblages of minerals one can reconstruct many aspects of the former chemical environment. By studying the record of changing conditions one may deduce information regarding the processes functioning to create the succession of chemical environments and the ore deposits they represent. The example of the OH vein at Creede, Colorado, shows a pH buffered by the K-feldspar + muscovite + quartz assemblage and the covariation of S2 and O2 buffered by the assemblage chlorite + pyrite + quartz. Boiling of the ore fluid led to its oxidation to hematite-bearing assemblages and simultaneously produced an intensely altered, sericitic capping over the vein in response to the condensation of vapors bearing acidic components. The solubility of metals as calculated from experimental and theoretical studies of mineral solubility appears too low by at least one or two powers of ten to explain the mineralization at Creede. In contrast to Creede where the mineral stabilities all point to a relatively consistent chemistry, the Mississippi Valley type deposits present a puzzle of conflicting chemical clues that are impossible to reconcile with any single equilibrium situation. Thus we must

  6. Physical-chemical conditions of ore deposition

    NASA Astrophysics Data System (ADS)

    Barton, Paul B.

    Ore deposits form under a wide range of physical and chemical conditions, but those precipitating from hot, aqueous fluids-i.e. the hydrothermal deposits-form generally below 700°C and at pressures of only 1 or 2 kbar or less. Natural aqueous fluids in rocks may extract metal and sulfur from a variety of rock types or may acquire them as a residual heritage from a crystallizing silicate magma. Ore-forming hydrothermal fluids never appear as hot springs (except in deep, submarine situations) because they boil, mix with surface waters, and cool, thereby losing their ore-bearing ability before reaching the surface. Mineral systems function as chemical buffers and indicators just as buffers and indicators function in a chemical laboratory. By reading the record written in the buffer/indicator assemblages of minerals one can reconstruct many aspects of the former chemical environment. By studying the record of changing conditions one may deduce information regarding the processes functioning to create the succession of chemical environments and the ore deposits they represent. The example of the OH vein at Creede, Colorado, shows a pH buffered by the K-feldspar + muscovite + quartz assemblage and the covariation of S 2 and O 2 buffered by the assemblage chlorite + pyrite + quartz. Boiling of the ore fluid led to its oxidation to hematite-bearing assemblages and simultaneously produced an intensely altered, sericitic capping over the vein in response to the condensation of vapors bearing acidic components. The solubility of metals as calculated from experimental and theoretical studies of mineral solubility appears too low by at least one or two powers of ten to explain the mineralization at Creede. In contrast to Creede where the mineral stabilities all point to a relatively consistent chemistry, the Mississippi Valley type deposits present a puzzle of conflicting chemical clues that are impossible to reconcile with any single equilibrium situation. Thus we must

  7. Mixing from below in hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Bons, Paul D.; Gomez-Rivas, Enrique; Markl, Gregor; Walter, Bejamin

    2014-05-01

    Unconformity-related hydrothermal ore deposits typically show indications of mixing of two end-member fluids: (a) hot, deep, rock-buffered basement brines and (b) colder fluids derived from the surface or overlying sediments. The hydromechanics of bringing these fluids together from above and below remain unclear. Classical percolative Darcy-flow models are inconsistent with (1) fluid overpressure indicated by fracturing and brecciation, (2) fast fluid flow indicated by thermal disequilibrium, and (3) strong fluid composition variations on the mm-scale, indicated by fluid inclusion analyses (Bons et al. 2012; Fusswinkel et al. 2013). We propose that fluids first descend, sucked down by desiccation reactions in exhumed basement. Oldest fluids reach greatest depths, where long residence times and elevated temperatures allow them the extensively equilibrate with their host rock, reach high salinity and scavenge metals, if present. Youngest fluids can only penetrate to shallower depths and can (partially) retain signatures from their origin, for example high Cl/Br ratios from the dissolution of evaporitic halite horizons. When fluids are released from all levels of the crustal column, these fluids mix during rapid ascent to form hydrothermal ore deposits. Mixing from below provides a viable hydromechanical mechanism to explain the common phenomenon of mixed shallow and deep fluids in hydrothermal ore deposits. Bons, P.D., Elburg, M.A., Gomez-Rivas, E. 2012. A review of the formation of tectonic veins and their microstructures. J. Struct. Geol. doi:10.1016/j.jsg.2012.07.005 Fusswinkel, T., Wagner, T., Wälle, M., Wenzel, T., Heinrich, C.A., Markl, M. 2013. Fluid mixing forms basement-hosted Pb-Zn deposits: Insight from metal and halogen geochemistry of individual fluid inclusions. Geology. doi:10.1130/G34092.1

  8. Supergene processes on ore deposits - a source of heavy metals

    SciTech Connect

    Martycak, K.; Zeman, J.; Vacek-Vesely, M.

    1994-03-01

    The study of supergene processes (i.e., secondary processes running in ore deposits and driven by thermodynamic nonequilibrium between ore- and rock-forming minerals and natural waters, gasses, etc.) is important in order to understand the migration of heavy metals from ore into their adjacent surroundings. The contamination of the local environment can be characterized by the composition of pore waters. The Pb-Zn-Cu ore deposits of Zlate Hory (Czech Republic) have been chosen for a detailed study of pore solutions. A simple model has been created to describe the evolution of supergene processes in the ore deposits. This model is based on the determination of chemical composition of pore solutions. The dilution of pore solutions of such mineral deposits results in acid mine drainage. Pore solutions can have, during specific stages of their evolution, relatively high concentrations of Cu (0.09 mol/kg), Zn (0.1 mol/kg), SO{sub 4} (0.8 mol/kg) and an extremely low pH (1.38). The supergene alteration of pyrite is the most important process determining the character of pore water. This reaction causes significant acidification and is a leading source of acid mine drainage. The leached zone originates from the interaction of pyrite and limonite. Increased concentrations of heavy metals and sulfates occur in pore waters. The dynamic composition of pore waters within ore deposits undergoing the supergene process can be used to distinguish: (1) three main zones - limonite, transition, and primary zone and (2) two areas - an area with the highest intensity of weathering processes and an area of weathering initiation. In these areas the rate of sulfide oxidation is higher as a result of low pH. From the study of these zones and areas we can further our knowledge of ore body, pore solution, acid mine drainage, and contamination of the local environment. 32 refs., 12 figs., 3 tabs.

  9. Hydrothermal ore deposit and geothermal analogs of nuclear waste repositories

    SciTech Connect

    Hackbarth, C.J.

    1985-01-01

    Hydrothermal ore deposits and active geothermal systems can provide important information on the response of a rock/ground water system to the emplacement of hot, radioactive nuclear waste. Congress has mandated that the first deep geologic repository be licensed by 1998, so that scientific investigation must be completed in a relatively short time. Laboratory studies are sometimes too short and on too small a scale to adequately simulate the geologic environment over thousands of years. Computer models are often highly simplified. Fortunately, data from the field of economic geology can help scientist anticipate future nuclear waste repository behaviors in a complex environment over long periods of time. Some phenomena in ore deposits are direct parallels to possible repository phenomena. Some ore and gangue minerals show colloidal textures, indicating that colloids may contribute to radionuclide redistribution in a repository. Wall rock alteration in ore deposits indicates the types of alteration to be expected in a repository. In addition to individual analogous phenomena, hydrothermal convection may develop in the ground water after emplacement of waste. Primary dispersion halos, paragenetic relationships, and fluid inclusion data from ore deposits can help to predict the size, shape, and duration of convection cells which might be expected around a repository. Such studies might also identify the significant effects of complex coupling between thermal, hydrological, chemical, and mechanical factors.

  10. Nanomineralogy and nanogeochemistry of ores from gold deposits of Uzbekistan

    NASA Astrophysics Data System (ADS)

    Koneev, R. I.; Khalmatov, R. A.; Mun, Yu. S.

    2010-12-01

    Gold deposits of Uzbekistan are localized in the Kyzylkum, Nurata, and Kurama ore districts of the Kyzylkum-Kurama metallogenic belt. They comprise a consecutive series of deposit types corresponding to the series of geochemical associations: (Au-W)—(Au-As)—(Au-Te)—(Au-Ag)—(Au-Sb)—(Au-Hg), which are arranged as a system of zones in orebodies, deposits, ore fields, and ore districts. The distribution of chemical elements characterized by average global concentrations in the crust within the ppm-ppb (10-6-10-9 t) range was studied in ores of gold deposits using an ICP MS Elan DRC II device. Mineral nanoassemblages with a grain size of 10-6 to 10-9 m were examined with a Jeol YXA 8800R Superprobe. The Au-W, Au-As, and Au-Te associations with Bi tellurides and maldonite in ore dominate at hypo- and meso-abyssal gold deposits of the Kyzylkum district (Muruntau, Myutenbay). The contribution of the Au-Sb association with Pb, Ag, and Fe sulfoantimonites and aurostibite increases at the Daughyztau, Kokpatas, and Amantaitau gold deposits. The Au-As, Au-Te, and Au-Sb associations with Bi tellurides, maldonite, sulfoantimonites, and aurostibite dominate at the mesoabyssal gold deposits of the Nurata district (Charmitan, Guzhumsay). The Au-Te and Au-Ag associations with Au, Ag, Pb, Sb, Bi, and Hg tellurides and Bi selenides dominate at the hypabyssal gold deposits of the Kurama district (Kochbulak, Kayragach). The gold-silver deposits of the Kyzylkum district (Kosmanachi, Vysokovol'tnoe) and the Kurama district (Kyzylalmasay, Arabulak) are close in composition. They are characterized by development of intermetallides, sulfides, sulfosalts, and selenides of Au-Ag and occasionally Au-Sb associations. Fineness of gold decreases from early to late geochemical associations, whereas the size of gold grains increases in the same direction from nanogold to visible gold. The studies at the micro- and nanolevel make it possible to establish the attributes of specific gold

  11. Compositional Variability of Rutile in Hydrothermal Ore Deposits

    NASA Astrophysics Data System (ADS)

    Clark, J. R.; Williams-Jones, A. E.

    2009-05-01

    Rutile is a relatively common accessory phase in many geological environments, and although it is almost always composed dominantly of TiO2, it is also associated with a wide range of minor and trace element substitutions. The most prominent minor elements that occur in rutile are Fe, Cr, V, Nb and Ta. Like Ti, the latter two elements are essentially immobile in most non-magmatic metallic ore deposits, and their concentrations in rutile are largely influenced by precursor mineral compositions. Iron, Cr and V concentrations vary considerably in rutile hosted by ore deposits, and reflect combinations of precursor mineral composition and the bulk chemistry of the local mineralized or altered rock environment. However, in hydrothermal alteration zones, rutile compositions are clearly anomalous compared to those in unaltered host rocks, and have distinctive elemental associations and substitutions in different types of ore deposits. We have evaluated the mineral chemistry of rutile in >40 ore deposits worldwide. In general, rutile in volcanogenic massive sulfide deposits contains Sn (and locally W, Sb and/or Cu). Rutile from mesothermal and related gold deposits invariably contains W, and in some of the larger and more important deposits, also contains Sb and/or V. Tungsten-bearing detrital rutile grains from the Witwatersrand suggest that paleoplacer mineralization may have had a mesothermal/orogenic gold source. In some magmatic-hydrothermal Pd-Ni-Cu deposits, rutile contains Ni and Cu. Rutile associated with granite-related Sn deposits has strongly elevated concentrations of Sn and W, and granite-pegmatite W-Sn deposits contain rutile with these elements plus Nb and Ta. The Olympic Dam deposit hosts rutile that is enriched in W, Sn and Cu. Rutile associated with porphyry and skarn Cu and Cu-Au deposits tends to contain elevated W, Cu (and sometimes V). Although many ore deposits have well-defined and diagnostic rutile compositions, there are some compositional

  12. Insights Into Ore Deposit Genesis Using Copper Isotopes

    NASA Astrophysics Data System (ADS)

    Maher, K. C.; Larson, P. B.; Ramos, F. C.; Gaspar, M.; Chang, Z.

    2002-12-01

    Advances in MC-ICPMS have renewed interest in the analysis of transition metal isotopes to better constrain the processes involved in ore deposition. At WSU we employ sample-standard bracketing to accurately and precisely measure copper isotope ratios of whole mineral dissolutions without normalizing to zinc. This approach bypasses the use of chromatography for samples without significant isobaric interferences avoiding potential fractionation resulting from chromatography. Comparisons of analyses of native copper and chalcopyrite samples with and without chromatographic purification are within error. Reproducibility measured using native copper and chalcopyrite is \\pm0.03\\permil (1\\sigma, relative to NIST 976) over 2 months. We have found the range of δ65Cu values in chalcopyrite from a variety of ore deposits to be -0.9\\permil to +3.1\\permil. δ65Cu values of native copper and bornite samples are more restricted (-0.8\\permil to 1.3\\permil, and -1.1\\permil to 1.0\\permil, respectively). Additional minerals, including chalcocite, mohawkite, azurite and cuprite, have been analyzed from a variety of ore depositional environments. Variations in δ65Cu values of individual mineral species within a single deposit or district have smaller ranges. For example, "hypogene" native copper samples from the Michigan Native Copper district show a restricted range of values (0.2\\permil to 0.4\\permil), over 100km strike of the district. In addition, different genetically related minerals in the same deposit show distinctive trends in δ65Cu values. For example, co-precipitated chalcopyrite-bornite pairs from three deposits (Resolution, AZ, Beaver-Harrison Mine, UT, and Ferrobamba, Peru) display consistently higher δ65Cu values in chalcopyrite relative to bornite. Results from the Tintaya district, Peru and Resolution, AZ suggest that variations in δ65Cu values may be systematic on the deposit scale. In both deposits, δ65Cu in chalcopyrite increases with distance from

  13. Geology and ore deposits of the Casto quadrangle, Idaho

    USGS Publications Warehouse

    Ross, Clyde P.

    1934-01-01

    The study of the Casto quadrangle was undertaken as the first item in a project to obtain more thorough knowledge of the general geology of southcentral Idaho on which to base study of the ore deposits of t he region. The quadrangle conta ins fragmentary exposures of Algonkian and Paleozoic sedimentary rocks, extensive deposits of old volcanic strata, presumably Permian, not heretofore recognized in this part of Idaho, and a thick succession of Oligocene(?) lava and pyroclastic rocks. The Idaho batholith and its satellites extend into the quadrangle, and in addition there a re large masses of Tertiary granitic rock, not previously distinguished in Idaho, and many Tertiary dikes, some of which are genetically associated with contact-metamorphic deposits. The area contains injection gneiss of complex origin, largely related to the Idaho batholith but in part resulting from injection by ~he Tertiary granitic rocks under relatively light load. Orogenic movement took place in Algonkian, Paleozoic, and Tertiary time. There is a summit peneplain or par tial peneplain of Tertiary, perhaps Pliocene age, and the erosional history since its elevation has been complex. The ore deposits include lodes and placers. The lodes are related to both the Idaho batholith and the Tert iary intrusive rocks and have yielded gold and copper ore of a total value of about 1,000,000. Placers, largely formed in an interglacial inter val, have yielded about an equal amount. There has been some prospecting but almost no production since 1916.

  14. Ore microscopy of the Paoli silver-copper deposit, Oklahoma

    USGS Publications Warehouse

    Thomas, C.A.; Hagni, R.D.; Berendsen, P.

    1991-01-01

    The Paoli silver-copper deposit is located in south-central Oklahoma, 56 km south-southeast from Norman, Oklahoma. It was mined for high-grade silver-copper near the beginning of this century, and intensive exploratory drilling during the early 1970's delineated unmined portions of the deposit. A collaborative study between the U.S.G.S., the Kansas Geological Survey, and the University of Missouri-Rolla was undertaken to provide new information on the character of red bed copper deposits of the Midcontinent region. The Paoli deposit has been interpreted to occur as a roll-front type of deposit. The silver and copper mineralization occurs within paleochannels in the Permian Wellington Formation. The silver-copper interfaces appear to be controlled by oxidation-reduction interfaces that are marked by grey to red color changes in the host sandstone. Ore microscopic examinations of polished thin sections show that unoxidized ore consists of chalcocite, digenite, chalcopyrite, covellite and pyrite; and oxidized ores are characterized by covellite, bornite, hematite and goethite. In sandstone-hosted ores, chalcocite and digenite replace dolomite and border clastic quartz grains. In siltstone-hosted ores, the copper sulfide grains have varied shapes; most are irregular in shape and 5-25 ??m across, others have euhedral shapes suggestive of pyrite crystal replacements, and some are crudely spherical and are 120-200 ??m across. Chalcopyrite is the predominant copper sulfide at depth. Covellite and malachite replace chalcocite and digenite near the surface. Silver only occurs as native silver; most as irregularly shaped grains 40-80 ??m across, but some as cruciform crystals that are up to 3.5 mm across. The native silver has been deposited after copper sulfides, and locally replaces chalcocite. Surficial nodules of pyrite, malachite and hematite locally are present in outcrops at the oxidation-reduction fronts. Polished sections of the nodules show that malachite forms a

  15. Application of natural analog studies to exploration for ore deposits

    SciTech Connect

    Gustafson, D.L.

    1995-09-01

    Natural analogs are viewed as similarities in nature and are routinely utilized by exploration geologists in their search for economic mineral deposits. Ore deposit modeling is undertaken by geologists to direct their exploration activities toward favorable geologic environments and, therefore, successful programs. Two types of modeling are presented: (i) empirical model development based on the study of known ore deposit characteristics, and (ii) concept model development based on theoretical considerations and field observations that suggest a new deposit type, not known to exist in nature, may exist and justifies an exploration program. Key elements that are important in empirical model development are described, and examples of successful applications of these natural analogs to exploration are presented. A classical example of successful concept model development, the discovery of the McLaughlin gold mine in California, is presented. The utilization of natural analogs is an important facet of mineral exploration. Natural analogs guide explorationists in their search for new discoveries, increase the probability of success, and may decrease overall exploration expenditure.

  16. Geology and ore deposits of the Pioche district, Nevada

    USGS Publications Warehouse

    Westgate, L.G.; Knopf, Adolph

    1932-01-01

    near the range but finer and making a clay flat along the west side of the Bristol Range and Highland quadrangles. The valley east of the Bristol-Highland Range, however, has outside drainage by way of Meadow Valley to the Virgin and Colorado Rivers. The stream in upper Meadow Valley and its tributaries have cut through the surface wash from the mountains and laid bare several hundred feet of white, yellow, and red water-laid Pliocene tuffs that lie in nearly the position in which they were laid down. This erosion has developed a striking badland topography in the Pliocene beds. HISTORICAL SUMMARY The general succession of events may be summarized as follows: 1. Sedimentation during most of Paleozoic time from Cambrian to Pennsylvanian. 2. Uplift, slight warping, and erosion. 3. Volcanism of perhaps late Mesozoic or early Tertiary time, producing lavas and tuffs. This period of volcanism may have lasted a long time and spanned one or more of the epochs of faulting. 4. Tilting and normal faulting. 5. Thrust faulting. 6. Quartz monzonite intrusions at Blind Mountain. 7. Normal block faulting of the Basin Range type. 8. Erosion of the faulted blocks to maturity and to essen-. tially the topography of to-day. 9. Outbursts of volcanic ash, probably in late Pliocene time, and the deposition of several hundred feet of water-laid tuffs in the valleys. 10. In Meadow Valley, valley cutting, which has produced a badland topography in the soft Pliocene tuffs and canyons where the streams cross the harder Paleozoic limestones. ECONOMIC GEOLOGY The Pioche district during four years in the early seventies was second only to the Comstock district in output of silver. The bonanza ore of those stirring times came from fissure veins in the Prospect Mountain quartzite, of Lower Cambrian age. In recent years the main interest has shifted to the bedded replacement deposits of silver-bearing lead-zinc sulphide ore occurring in the limestone members of the Pioche shale a type of ore body

  17. Precambrian rift: genesis of strata-bound ore deposits.

    PubMed

    Kanasewich, E R

    1968-09-01

    Study of deep seismic reflections has detected a Precambrian rift valley below flat-lying sediments in southern Alberta. The anomalous magnetic and gravity trends show that the rift is continuous across Alberta and British Columbia (through the Kimberley lead-zinc field) and possibly the Coeur d'Alene mining district of Idaho. There is evidence that these ore bodies were deposited in a Precambrian rift under conditions similar to those prevailing in the hot-brine areas of the modern Red Sea.

  18. Empirical metallogeny. Depositional environments, lithologic associations and metallic ores, Vol. 1: Phanerozoic environments, associations and deposits

    SciTech Connect

    Laznicka, P.

    1985-01-01

    This is a single source of data on metallic deposits and their worldwide distribution. With over 1,750 pages it contains: 594 figures illustrating ore styles and their setting; 113 tables providing concise but highly quantitative data on several thousand locality examples; 4 indexes (general, locality, genetic, metals) enabling rapid and thorough searches; and more than 2,000 references. This body of information on metallic ore deposits is arranged by environments in which they presently form or lithologic associations in which they occur. The organization of the book follows the approach employed in regional mineral-potential evaluation and exploration.

  19. Geology and ore deposits of the Klondike Ridge area, Colorado

    USGS Publications Warehouse

    Vogel, John David

    1960-01-01

    The region described in this report is in the northeastern part of the Colorado Plateau and is transitional between two major structural elements. The western part is typical of the salt anticline region of the Plateau, but the eastern part has features which reflect movements in the nearby San Juan Mountains. There are five major structural elements in the report area: the Gypsum Valley anticline, Dry Creek Basin, the Horse Park fault block, Disappointment Valley, and the Dolores anticline. Three periods of major uplift are recognized In the southeastern end of the Gypsum Valley anticline. Each was followed by collapse of the overlying strata. Erosion after the first two periods removed nearly all topographic relief over the anticline; erosion after the last uplift has not yet had a profound effect on the topography except where evaporite beds are exposed at the surface. The first and greatest period of salt flow and anticlinal uplift began in the late Pennsylvanian and continued intermittently and on an ever decreasing scale into the Early Cretaceous. Most movement was in the Permian and Triassic periods. The second period of uplift and collapse was essentially contemporaneous with widespread tectonic activity on. the northwestern side of the San Juan Mountains and may have Occurred in the Oligocene and Miocene epochs. Granogabbro sills and dikes were intruded during the middle or upper Tertiary in Disappointment Valley and adjoining parts of the Gypsum Valley and Dolores anticlines. The third and mildest period of uplift occurred in the Pleistocene and was essentially contemporaneous with the post-Hinsdale uplift of the San Juan Mountains. This uplift began near the end of the earliest, or Cerro, stage of glaciation. Uranium-vanadium, manganese, and copper ore as well as gravel have been mined in the Klondike district. All deposits are small, and few have yielded more than 100 tons of ore. Most of the latter are carnotite deposits. Carnotite occurs in the lower

  20. Analytical fingerprint for tantalum ores from African deposits

    NASA Astrophysics Data System (ADS)

    Melcher, F.; Graupner, T.; Sitnikova, M.; Oberthür, T.; Henjes-Kunst, F.; Gäbler, E.; Rantitsch, G.

    2009-04-01

    Kibaran age either show flat patterns for most tantalites, rising values from the LREE to the HREE, or trough-like patterns. Eu anomalies are strongly negative in columbite-tantalite from the Alto Ligonha Province in Mozambique, from the Namaqualand Province (Namibia, South Africa), and from Zimbabwe. Four main age populations of coltan deposits in Africa were revealed: (1) Archean (>2.5 Ga), (2) Paleoproterozoic (2.1-1.9 Ga), (3) early Neoproterozoic ("Kibaran", 1.0-0.9 Ga), and (4) late Neoproterozoic to early Paleozoic (Pan-African; ca. 0.6-0.4 Ga). Currently, we focus on the resolution of the fingerprinting system from region via ore province down to deposit scale, establishing a large and high-quality analytical data base, and developing fast-screening and low-cost methods. Analytical flow-charts and identification schemes for coltan ores will be presented at the Conference. The analytical results obtained so far indicate that a certification scheme including fingerprinting of sources of coltan ores is feasible. The methodology developed is capable to assist in the establishment of a control instrument in an envisaged certification of the production and trade chain of coltan.

  1. Exploration and local forecast of gold-ore deposits based on typomorphic properties of pyrite

    NASA Astrophysics Data System (ADS)

    Pshenichkin, A. Ya; Ananyev, Yu S.; Bushmano, A. I.; Abramova, R. N.

    2015-11-01

    The article describes the data in exploration and local forecast of gold-ore deposits based on typomorphic pyrite properties. The pyrite properties: crystal shape, impurity-elements and thermal EMF change in relation to the deposit formation conditions are consistent with the mineralogical and geochemical zoning of ore bodies and deposits. In this case, it is possible to evaluate the ore zone erosion, prospectivity and productivity of the ore bodies at depth and flanks. Mineralogical sampling on pyrite and gold should be conducted on the basis of other methods during exploration and mining.

  2. Hybrid gravity survey to search for submarine ore deposit

    NASA Astrophysics Data System (ADS)

    Araya, A.; Kanazawa, T.; Fujimoto, H.; Shinohara, M.; Yamada, T.; Mochizuki, K.; Iizasa, K.; Ishihara, T.; Omika, S.

    2011-12-01

    Along with seismic surveys, gravity survey is a useful method to profile the underground density structure. We propose a hybrid gravity survey using gravimeters and gravity gradiometers to detect submarine ore deposits as density anomalies by towing the instruments using an AUV (Autonomous Underwater Vehicle) or an ROV (Remotely Operated Vehicle). Gravimeters measure the regional density structure below the seafloor, whereas gravity gradiometers are sensitive to localized mass distribution. A gravity gradiometer comprises two accelerometers arranged with a vertical separation, and a gravity gradient can be obtained from the acceleration difference. Compared to gravimeters, gravity gradiometers are insensitive to common disturbances such as parallel acceleration, thermal drift, and apparent gravity effect (Eötvös effect). We made two accelerometers using astatic pendulums, and obtained common acceleration reduction more than two orders of magnitude. With these pendulums of 500-mm separation, resolution of 7E (=7x10^{-9}(1/s^2)), enough to detect a typical ore deposit buried 50m below the seafloor, was evaluated. During measurements using a submersible mobile object, instrument orientation is required to be controlled to keep verticality and to reduce centrifugal force associated with rotation of the instrument. Using a gyro and a tiltmeter, angular rotation was shown to be controlled within 0.001deg/s which corresponds to 0.3E in effective gravity gradient due to the centrifugal force. In this paper, target of this research, details of the instruments and their performance, and development for the submarine gravity survey using an AUV will be presented.

  3. Ore-fluid evolution at the Getchell Carlin-type gold deposit, Nevada, USA

    USGS Publications Warehouse

    Cline, J.S.; Hofstra, A.A.

    2000-01-01

    Minerals and fluid-inclusion populations were examined using petrography, microthermometry, quadrupole mass-spectrometer gas analyses and stable-isotope studies to characterize fluids responsible for gold mineralization at the Getchell Carlin-type gold deposit. The gold-ore assemblage at Getchell is superimposed on quartz-pyrite vein mineralization associated with a Late-Cretaceous granodiorite stock that intruded Lower-Paleozoic sedimentary rocks. The ore assemblage, of mid-Tertiary age, consists of disseminated arsenian pyrite that contains submicrometer gold, jasperoid quartz, and later fluorite and orpiment that fill fractures and vugs. Late ore-stage realgar and calcite enclose ore-stage minerals. Pre-ore quartz trapped fluids with a wide range of salinities (1 to 21 wt.% NaCl equivalent), gas compositions (H2O, CO2, and CH4), and temperatures (120 to >360??C). Oxygen- and hydrogen-isotope ratios indicate that pre-ore fluids likely had a magmatic source, and were associated with intrusion of the granodiorite stock and related dikes. Ore-stage jasperoid contains moderate salinity, aqueous fluid inclusions trapped at 180 to 220??C. Ore fluids contain minor CO2 and trace H2S that allowed the fluid to react with limestone host rocks and transport gold, respectively. Aqueous inclusions in fluorite indicate that fluid temperatures declined to ~175??C by the end of ore-stage mineralization. As the hydrothermal system collapsed, fluid temperatures declined to 155 to 115??C and realgar and calcite precipitated. Inclusion fluids in ore-stage minerals have high ??D(H2O) and ??18O(H2O) values that indicate that the fluid had a deep source, and had a metamorphic or magmatic origin, or both. Late ore-stage fluids extend to lower ??D(H2O) values, and have a wider range of ??18O(H2O) values suggesting dilution by variably exchanged meteoric waters. Results show that deeply sourced ore fluids rose along the Getchell fault system, where they dissolved carbonate wall rocks and

  4. Analog Experiments on Sulfide Foams in Magmatic Ore Deposits

    NASA Astrophysics Data System (ADS)

    Leitch, A. M.; Dahn, D.; Zavala, K.

    2009-05-01

    Metal sulfides form as an immiscible phase from silicate magmas. Dynamic mingling and unmingling of the two phases is important for the development of economic deposits: mingling promotes enrichment of the sulfide in valuable metals, and subsequent unmingling generates massive sulfide. Analog experiments were carried out to investigate mingling processes in immiscible systems, using oil, water and small beads to represent magma, sulfide liquid and silicate crystals. Stirring or injection led to the formation of a foam of analog sulfide droplets within an analog silicate framework. We propose that the partial collapse of such a foam explains massive sulfide lenses at the Voisey's Bay magmatic sulfide deposit, and that crystallization of silicate crystals in the remaining foam walls generates 'net-textured' ores. In the experiments, solid particles had a profound effect on unmingling: analog sulfide droplets were stably contained within analog crystal-rich magma and did not coalesce. We therefore suggest that 'net' and 'leopard' textures in disseminated sulfides indicate mingling of sulfide with crystal-poor magma, whereas isolated disseminated patches of sulfide indicate mingling with a crystal-rich magma.

  5. Magnetite mineral nanoparticles synthesized naturally in an iron ore deposit

    NASA Astrophysics Data System (ADS)

    Rivas-Sanchez, M. L.; Alva-Valdivia, L. M.

    2013-05-01

    We performed a mineralogical characterization and mineral magnetism study of the Peña Colorada iron ore, Mexico. The ore is formed partly by intergranular magnetite intergrowed with berthierine (Fe,Mg,Al)6(Si,Al)4O10(OH)8. The magnetite nanoparticles are forming aggregates of wide grain size spectra, from micro to nanometer scale. The smallest aggregates are formed by magnetite nanoparticles 2 to 30 grain size range, showing unusual physical and chemical behavior. The continuous agglomeration of nanoparticles formed more denser and compact magnetite microparticles. A magnetite concentrate to micrometric scale was reduced and divided into distinct range sizes: 85-56 μm, 56-30 μm, 30-22 μm, 22-15 μm, 15-10 μm, 10-7 μm and 7-1 μm. Nanometric-scale magnetite 2-30 nm was identified by using high resolution Transmission Electron Microscopy (HRTEM). The magnetite and minerals associated were characterized by X-ray diffraction, transmitted and reflected light polarization, microscope and electron probe X-ray micro-analyzer, differential thermal analysis, gravimetric thermal analysis, and high-resolution transmission electron microscopy. Besides, results of Mössbauer spectroscopy, frequency-dependent magnetic susceptibility, isothermal remanent magnetization and magnetic susceptibility versus temperature were important in the research related to the origin of this deposit. To study magnetite nanoparticles, agglomeration processes and temperature effect implications, we developed an experimental process to re-create the environmental conditions that originated this nanoparticles. These processes start with direct precipitation to synthesize magnetite nanoparticles through a thermal and dehydration treatment of the berthierine base mineral, using diverse temperature ranges, from 360 °C to 750 °C and treatment time of two hours. This process allowed the nucleation and crystalline growth of a high number of magnetite nano-crystals with average size of 2 to 6 nm

  6. Localization conditions and ore mineralogy of the Ulziit hydrogenic uranium deposit, Mongolia

    NASA Astrophysics Data System (ADS)

    Grechukhin, M. N.; Doinikova, O. A.; Ignatov, P. A.; Rassulov, V. A.

    2016-05-01

    Information on the speciation of uranium minerals in ore of the recently discovered Ulziit uranium deposit in Mongolia is given for the first time. The ore composition has been studied by analytical scanning electron microscopy and local laser luminescent spectroscopy. The ore formed as a result of epigenetic redox processes. Transition from permeable variegated fan sediments to poorly permeable gray-colored coalbearing lacustrine-boggy sediments is the main ore-controlling factor. High-tech uranium mining with borehole in-situ leaching is feasible.

  7. Sedimentary carbonate-hosted giant Bayan Obo REE-Fe-Nb ore deposit of Inner Mongolia, China; a cornerstone example for giant polymetallic ore deposits of hydrothermal origin

    USGS Publications Warehouse

    Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Tatsumoto, M.; Junwen, Wang; Conrad, J.E.; McKee, E.H.; Zonglin, Hou; Qingrun, Meng; Shengguang, Huang

    1997-01-01

    Detailed, integrative field and laboratory studies of the textures, structures, chemical characteristics, and isotopically determined ages and signatures of mineralization of the Bayan Obo deposit provided evidence for the origin and characteristics favorable for its formation and parameters necessary for defining giant polymetallic deposits of hydrothermal origin. Bayan Obo is an epigenetic, metasomatic, hydrothermal rare earth element (REE)-Fe-Nb ore deposit that is hosted in the metasedimentary H8 dolostone marble of the Middle Proterozoic Bayan Obo Group. The metasedimentary sequence was deposited on the northern continental slope of the North China craton. The mine area is about 100 km south of the suture marking Caledonian subduction of the Mongolian oceanic plate from the north beneath the North China craton. The mineralogy of the deposit is very complex, consisting of more than 120 different minerals, some of which are epigenetic minerals introduced by hydrothermal solutions, and some of which are primary and secondary metamorphic minerals. The major REE minerals are monazite and bastnaesite, whereas magnetite and hematite are the dominant Fe-ore minerals, and columbite is the most abundant Nb mineral. Dolomite, alkali amphibole, fluorite, barite, aegirine augite, apatite, phlogopite, albite, and microcline are the most widespread gangue minerals. Three general types of ores occur at Bayan Obo: disseminated, banded, and massive ores. Broad zoning of these ore types occurs in the Main and East Orebodies. Disseminated ores are in the outermost zone, banded ores are in the intermediate zone, and massive ores are in the cores of the orebodies. On the basis of field relations, host rocks, textures, structures, and mineral assemblages, many varieties of these three types of ores have been recognized and mapped. Isotopic dating of monazite, bastnaesite, aeschynite, and metamorphic and metasomatic alkali amphiboles associated with the deposit provides constraints

  8. Rock-magnetism and ore microscopy of the magnetite-apatite ore deposit from Cerro de Mercado, Mexico

    NASA Astrophysics Data System (ADS)

    Alva-Valdivia, L. M.; Goguitchaichvili, A.; Urrutia-Fucugauchi, J.; Caballero-Miranda, C.; Vivallo, W.

    2001-03-01

    Rock-magnetic and microscopic studies of the iron ores and associated igneous rocks in the Cerro de Mercado, Mexico, were carried out to determine the magnetic mineralogy and origin of natural remanent magnetization (NRM), related to the thermo-chemical processes due to hydrothermalism. Chemical remanent magnetization (CRM) seems to be present in most of investigated ore and wall rock samples, replacing completely or partially an original thermoremanent magnetization (TRM). Magnetite (or Ti-poor titanomagnetite) and hematite are commonly found in the ores. Although hematite may carry a stable CRM, no secondary components are detected above 580°, which probably attests that oxidation occurred soon enough after the extrusion and cooling of the ore-bearing magma. NRM polarities for most of the studied units are reverse. There is some scatter in the cleaned remanence directions of the ores, which may result from physical movement of the ores during faulting or mining, or from perturbation of the ambient field during remanence acquisition by inhomogeneous internal fields within these strongly magnetic ore deposits. The microscopy study under reflected light shows that the magnetic carriers are mainly titanomagnetite, with significant amounts of ilmenite-hematite minerals, and goethite-limonite resulting from alteration processes. Magmatic titanomagnetites, which are found in igneous rocks, show trellis, sandwich, and composite textures, which are compatible with high temperature (deuteric) oxy-exsolution processes. Hydrothermal alteration in ore deposits is mainly indicated by martitization in oxide minerals. Grain sizes range from a few microns to >100 mm, and possible magnetic state from single to multidomain, in agreement with hysteresis measurements. Thermal spectra, continuous susceptibility measurements, and IRM (isothermal remanent magnetization) acquisition suggest a predominance of spinels as magnetic carriers, most probably titanomagnetites with low

  9. Lacustrine-humate model for primary uranium ore deposits, Grants Uranium Region, New Mexico

    SciTech Connect

    Turner-Peterson, C.E.

    1985-11-01

    Two generations of uranium ore, primary and redistributed, occur in fluvial sandstones of the Upper Jurassic Morrison Formation in the San Juan basin; the two stages of ore formation can be related to the hydrologic history of the basin. Primary ore formed soon after Morrison deposition, in the Late Jurassic to Early Cretaceous, and a model, the lacustrine-humate model, is offered that views primary mineralization as a diagenetic event related to early pore fluid evolution. The basic premise is that the humate, a pore-filling organic material closely associated with primary ore, originated as humic acids dissolved in pore waters of greenish-gray lacustrine mudstones deposited in the mud-flat facies of the Brushy Basin Member and similar K shale beds in the Westwater Canyon Member. During compaction associated with early burial, formation water expelled from lacustrine mudstone units carried these humic acids into adjacent sandstone beds where the organics precipitated, forming the humate deposits that concentrated uranium. During the Tertiary, much later in the hydrologic history of the basin, when Jurassic sediments were largely compacted, oxygenated ground water flowed basinward from uplifted basin margins. This invasion of Morrison sandstone beds by oxidizing ground waters redistributed uranium from primary ores along redox boundaries, forming ore deposits that resemble roll-front-type uranium ores. 11 figures.

  10. Lacustrine-humate model for primary uranium ore deposits, Grants Uranium Region, New Mexico

    SciTech Connect

    Turner-Peterson, C.E.

    1985-11-01

    Two generations of uranium ore, primary and redistributed, occur in fluvial sandstones of the Upper Jurassic Morrison Formation in the San Juan basin; the two stages of ore formation can be related to the hydrologic history of the basin. Primary ore formed soon after Morrison deposition, in the Late Jurassic to Early Cretaceous, and a model, the lacustrine-humate model, is offered that views primary mineralization as a diagenetic event related to early pore fluid evolution. The basic premise is that the humate, a pore-filling organic material closely associated with primary ore, originated as humic acids dissolved in pore waters of greenish-gray lacustrine mudstones deposited in the mud-flat facies of the Brushy Basin Member and similar ''K'' shale beds in the Westwater Canyon Member. During compaction associated with early burial, formation water expelled from lacustrine mudstone units carried these humic acids into adjacent sandstone beds where the organics precipitated, forming the humate deposits that concentrated uranium. During the Tertiary, much later in the hydrologic history of the basin, when Jurassic sediments were largely compacted, oxygenated ground water flowed basinward from uplifted basin margins. This invasion of Morrison sandstone beds by oxidizing ground waters redistributed uranium from primary ores along redox boundaries, forming ore deposits that resemble roll-front-type uranium ores.

  11. Mineralogical and geochemical characteristics of the Noamundi-Koira basin iron ore deposits (India)

    NASA Astrophysics Data System (ADS)

    Mirza, Azimuddin; Alvi, Shabbar Habib; Ilbeyli, Nurdane

    2015-04-01

    India is one of the richest sources of iron ore deposits in the world; and one of them is located in the Noamundi-Koira basin, Singhbhum-Orissa craton. The geological comparative studies of banded iron formation (BIF) and associated iron ores of Noamundi-Koira iron ore deposits, belonging to the iron ore group in eastern India, focus on the study of mineralogy and major elemental compositions along with the geological evaluation of different iron ores. The basement of the Singhbhum-Orissa craton is metasedimentary rocks which can be traced in a broadly elliptical pattern of granitoids, surrounded by metasediments and metavolcanics of Greenstone Belt association. The Singhbhum granitoid is intrusive into these old rocks and to younger, mid Archaean metasediments, including iron formations, schists and metaquartzites and siliciclastics of the Precambrian Iron Ore Group (Saha et al., 1994; Sharma, 1994). The iron ore of Noamundi-Koira can be divided into seven categories (Van Schalkwyk and Beukes 1986). They are massive, hard laminated, soft laminated, martite-goethite, powdery blue dust and lateritic ore. Although it is more or less accepted that the parent rock of iron ore is banded hematite jasper (BHJ), the presence of disseminated martite in BHJ suggests that the magnetite of protore was converted to martite. In the study area, possible genesis of high-grade hematite ore could have occurred in two steps. In the first stage, shallow, meteoric fluids affect primary, unaltered BIF by simultaneously oxidizing magnetite to martite and replacing quartz with hydrous iron oxides. In the second stage of supergene processes, deep burial upgrades the hydrous iron oxides to microplaty hematite. Removal of silica from BIF and successive precipitation of iron resulted in the formation of martite- goethite ore. Soft laminated ores were formed where precipitation of iron was partial or absent. The leached out space remains with time and the interstitial space is generally filled

  12. Geology and ore fluid geochemistry of the Jinduicheng porphyry molybdenum deposit, East Qinling, China

    NASA Astrophysics Data System (ADS)

    Li, Hongying; Ye, Huishou; Wang, Xiaoxia; Yang, Lei; Wang, Xiuyuan

    2014-01-01

    Jinduicheng deposit is a giant Mesozoic porphyry Mo system deposit in the East Qinling molybdenum belt, Shaanxi Province, China. The mineralization is associated with the I-type Jinduicheng granite porphyry. Both the porphyry stock and country rocks underwent intense hydrothermal alteration. The alteration, with increasing distance from the parent intrusion, changes from silicification, through potassic and phyllic assemblages, carbonation, to propylitic assemblages. Molybdenite, the dominant ore mineral, occurs in veinlets, most of which are hosted by the altered country rocks, with less than 25% of the ore in the porphyry body. The hydrothermal system comprises four stages, including pre-ore quartz and K-feldspar; two ore stages of quartz, K-feldspar, molybdenite, and Pb- And Zn-bearing sulfides; and post-ore quartz and carbonate. Six main types of primary fluid inclusions are present in hydrothermal quartz, including two-phase aqueous, one-phase aqueous, three-phase CO2-bearing, CO2-dominated fluid inclusions, gas inclusions, and melt inclusions. The homogenization temperatures of fluid inclusions range from 210 to 290 °C in the pre-ore stage, 150-310 °C in ore stage I, 150-360 °C in the ore stage II, and 195-325 °C in the post-ore stage quartz. Estimated salinities of the ore-forming fluids range from 6.9 to 13.5, 4.3 to 12.3, 6.2 to 12.4, and 3.4 to 9.9 wt.% NaCl equiv. in stages 1-4, respectively. The δ34S values of pyrite in the two ore stages range from 2.8‰ to 4.3‰, whereas the δ34S values of molybdenite range from 2.9‰ to 6.2‰. The data suggest both magmatic and crustal sources of sulfur. The δD and δ18O values for the hydrothermal fluids are -57.2‰ to -84.4‰ and 8.0‰ to -3.2‰, respectively. The fluid inclusion and stable data indicate that the pre-ore hydrothermal fluids were mostly of magmatic origin, but the fluids responsible for ore deposition were mixed magmatic and meteoric, and eventually meteoric water dominated the system

  13. Geology and ore deposits of the Whitepine area, Tomichi mining district, Gunnison County, Colorado

    USGS Publications Warehouse

    Robinson, Charles Sherwood

    1956-01-01

    The Tomichi mining district is on the western slope of the Continental Divide near the southern end of the Sawatch Range in southeastern Gunnison County, Colorado. The most productive part of the Tomichi district was the Whitepine area. It is estimated that since the discovery of ore in 1879 the area has produced approximately $7,000,000, principally in lead and zinc, with lesser amounts of silver, copper, and gold. Geologically, the Whitepine area is a faulted syncline of Paleozoic rocks that was intruded by Tertiary igneous rocks. The oldest rock of the area is the Silver Plume granite of pre-Cambrian age. Deposited upon this successively were the Sawatch quartzite (Late Cambrian), Manitou dolomite (Early Ordovician), Harding quartzite (Middle Ordovician), Fremont dolomite (Lade Ordovician), Chaffee formation (Late Devonian), Leadville limestone (Late Mississippian), and Beldon shale (Late Pennsylvanian); a total thickness of about 1,450 feet. During the Laramide Revolution, the sedimentary rocks were folded into a broad northward-plunging syncline, faulted, and intruded by a series of igneous rocks. The igneous rocks, in order of relative age from oldest to youngest, are: a rhyolite stock, the Princeton quartz monzonite batholith, quartz monzonite or quartz latite porphyry dikes, and rhyolite or pitchstone porphyry dikes. The ore deposits of the Whitepine area may be classified into replacement deposits, vein deposits, and contact metamorphic deposits. The replacement deposits may be further subdivided into deposits along faults and bedded deposits. Of the types of deposits, the most productive have been the replacement deposits along faults. The major replacement deposits along faults are those of the Akron, Morning Star, and Victor mines. The ore deposits of these mines are in the foot wall of the Star faults in the Akron mine in the Manitou dolomite and in the Morning Star and Victor mines in the Leadville limestone. The chief bedded replacement deposits are

  14. Ore deposits of the Gilman District, Eagle County, Colorado

    USGS Publications Warehouse

    Lovering, T.S.; Tweto, Ogden; Lovering, T.G.

    1978-01-01

    The Gilman mining district, known also in the past as the Red Cliff district, is in the mountains of southeastern Eagle County, west-central Colorado. The district is the leading source of zinc in Colorado and one of the major base-metal mining districts in the State. As valued at the time of production, total output of zinc, silver, copper, lead, and gold through 1972 was about $328 million. About 90 percent of this total was produced after 1930. The productive part of the district is an area of about 3 square miles (7.8 square kilometers) on the northeast side of the deep canyon of the Eagle River between the small towns of Gilman and Red Cliff. The ore deposits are principally replacement deposits in dolomites of Mississippian and Devonian age and in quartzite of Cambrian age. A few productive veins occur in Precambrian rocks. The replacement deposits crop out in the cliffs of the canyon wall and extend northeastward downdip beneath Battle Mountain, which is composed of a thick sequence of Pennsylvanian clastic rocks. The deposits were originally worked through several separate mines along the canyon wall, but since 1918, all deposits in dolomite rocks, except some small ones near Red Cliff, have been worked through the Eagle mine of the New Jersey Zinc Company at Gilman. The Gilman district lies on the eastern flank of the huge anticline of the Sawatch Range, near the steeply plunging north end of the anticline. Sedimentary rocks on the flank of this part of the anticline dip homoclinally northeastward to a synclinal axis about 8 mi (miles) (13 km (kilometers> northeast of Gilman and then rise more steeply to the Gore fault at the edge of the Gore Range. The homocline is broken by only a few faults most of which have displacements of less than 100 ft (feet) (30 m (meters>. In contrast, the underlying Precambrian rocks are broken by numerous faults and shear zones related to the Homestake shear zone, a northeast-trending master shear zone several miles wide

  15. Complex mineralization at large ore deposits in the Russian Far East

    NASA Astrophysics Data System (ADS)

    Schneider, A. A.; Malyshev, Yu. F.; Goroshko, M. V.; Romanovsky, N. P.

    2011-04-01

    Genetic and mineralogical features of large deposits with complex Sn, W, and Mo mineralization in the Sikhote-Alin and Amur-Khingan metallogenic provinces are considered, as well as those of raremetal, rare earth, and uranium deposits in the Aldan-Stanovoi province. The spatiotemporal, geological, and mineralogical attributes of large deposits are set forth, and their geodynamic settings are determined. These attributes are exemplified in the large Tigriny Sn-W greisen-type deposit. The variation of regional tectonic settings and their spatial superposition are the main factor controlling formation of large deposits. Such a variation gives rise to multiple reactivation of the ore-magmatic system and long-term, multistage formation of deposits. Pulsatory mineralogical zoning with telescoped mineral assemblages related to different stages results in the formation of complex ores. The highest-grade zones of mass discharge of hydrothermal solutions are formed at the deposits. The promising greisen-type mineralization with complex Sn-W-Mo ore is suggested to be an additional source of tungsten and molybdenum. The Tigriny, Pravourminsky, and Arsen'evsky deposits, as well as deposits of the Komsomol'sk and Khingan-Olonoi ore districts are examples. Large and superlarge U, Ta, Nb, Be, and REE deposits are localized in the southeastern Aldan-Stanovoi Shield. The Ulkan and Arbarastakh ore districts attract special attention. The confirmed prospects of new large deposits with Sn, W, Mo, Ta, Nb, Be, REE, and U mineralization in the south of the Russian Far East assure expediency of further geological exploration in this territory.

  16. Banded sulfide-magnetite ores of Mauk copper massive sulfide deposit, Central Urals: Composition and genesis

    NASA Astrophysics Data System (ADS)

    Safina, N. P.; Maslennikov, V. V.; Maslennikova, S. P.; Kotlyarov, V. A.; Danyushevsky, L. V.; Large, R. R.; Blinov, I. A.

    2015-05-01

    The results of investigation of metamorphosed sulfide-magnetite ores from the Mauk deposit located within the Main Ural Fault at the junction of Tagil and Magnitogorsk massive sulfide zones are discussed. The ore-hosting sequence comprises metamorphic rocks formed from basalt, carbonaceous and carbonaceous-cherty siltstone, and lenticular serpentinized ultramafic bodies. The ores of the deposit are represented by banded varieties and less frequent breccia. The clastic origin of the banded ore is indicated by load casts at the bottom of sulfide beds, alternation of sulfide and barren beds, and the truncation of the growth zones of pyrite crystals. Pyrite, pyrrhotite, chalcopyrite, sphalerite, and magnetite are the major minerals of the banded ores. The internal structure of the listed minerals testifies to the deep metamorphic recrystallization of primary hydrothermal-sedimentary ores accompanied with deformation. Cubanite, pyrrhotite, mackinawite, greigite, and gold are enclosed in metacrysts of pyrite, magnetite, and chalcopyrite. The accessory minerals of the Pb-Bi-Te, Bi-Te, and Ag-Te systems as well as uraninite have been found at the Mauk deposit for the first time. Magnetite predominantly replaces pyrite and less frequently chalcopyrite, pyrrhotite, and gangue minerals. It was established that the major carriers of As and Co are crystals of metamorphic pyrite. Chalcopyrite is the major carrier of Zn, Sn, Te, Pb, Bi, and Ag. Admixture of Fe and Cu is typical of sphalerite, and Se and Ni are characteristic of pyrrhotite. Ti, V, Mn, Sb, As, Ba, and U are concentrated in magnetite. The banded ores of the Mauk deposit are suggested as having been transformed in several stages: diagenesis, anadiagenesis, epidiagenesis ( t < 300°C), and amphibolite facies metamorphism ( t > 500°C).

  17. Remobilisation features and structural control on ore grade distribution at the Konkola stratiform Cu-Co ore deposit, Zambia

    NASA Astrophysics Data System (ADS)

    Torremans, K.; Gauquie, J.; Boyce, A. J.; Barrie, C. D.; Dewaele, S.; Sikazwe, O.; Muchez, Ph.

    2013-03-01

    The Konkola deposit is a high grade stratiform Cu-Co ore deposit in the Central African Copperbelt in Zambia. Economic mineralisation is confined to the Ore Shale formation, part of the Neoproterozoic metasedimentary rocks of the Katanga Supergroup. Petrographic study reveals that the copper-cobalt ore minerals are disseminated within the host rock, sometimes concentrated along bedding planes, often associated with dolomitic bands or clustered in cemented lenses and in layer-parallel and irregular veins. The hypogene sulphide mineralogy consists predominantly of chalcopyrite, bornite and chalcocite. Based upon relationships with metamorphic biotite, vein sulphides and most of the sulphides in cemented lenses were precipitated during or after biotite zone greenschist facies metamorphism. New δ34S values of sulphides from the Konkola deposit are presented. The sulphur isotope values range from -8.7‰ to +1.4‰ V-CDT for chalcopyrite from all mineralising phases and from -4.4‰ to +2.0‰ V-CDT for secondary chalcocite. Similarities in δ34S for sulphides from different vein generations, earlier sulphides and secondary chalcocite can be explained by (re)mobilisation of S from earlier formed sulphide phases, an interpretation strongly supported by the petrographic evidence. Deep supergene enrichment and leaching occurs up to a km in depth, predominantly in the form of secondary chalcocite, goethite and malachite and is often associated with zones of high permeability. Detailed distribution maps of total copper and total cobalt contents of the Ore Shale formation show a close relationship between structural features and higher copper and lower cobalt contents, relative to other areas of the mine. Structural features include the Kirilabombwe anticline and fault zones along the axial plane and two fault zones in the southern limb of the anticline. Cobalt and copper behave differently in relation to these structural features. These structures are interpreted to have

  18. Mineralogical and geochemical characteristics of the Noamundi-Koira basin iron ore deposits (India)

    NASA Astrophysics Data System (ADS)

    Mirza, Azimuddin; Alvi, Shabbar Habib; Ilbeyli, Nurdane

    2015-04-01

    India is one of the richest sources of iron ore deposits in the world; and one of them is located in the Noamundi-Koira basin, Singhbhum-Orissa craton. The geological comparative studies of banded iron formation (BIF) and associated iron ores of Noamundi-Koira iron ore deposits, belonging to the iron ore group in eastern India, focus on the study of mineralogy and major elemental compositions along with the geological evaluation of different iron ores. The basement of the Singhbhum-Orissa craton is metasedimentary rocks which can be traced in a broadly elliptical pattern of granitoids, surrounded by metasediments and metavolcanics of Greenstone Belt association. The Singhbhum granitoid is intrusive into these old rocks and to younger, mid Archaean metasediments, including iron formations, schists and metaquartzites and siliciclastics of the Precambrian Iron Ore Group (Saha et al., 1994; Sharma, 1994). The iron ore of Noamundi-Koira can be divided into seven categories (Van Schalkwyk and Beukes 1986). They are massive, hard laminated, soft laminated, martite-goethite, powdery blue dust and lateritic ore. Although it is more or less accepted that the parent rock of iron ore is banded hematite jasper (BHJ), the presence of disseminated martite in BHJ suggests that the magnetite of protore was converted to martite. In the study area, possible genesis of high-grade hematite ore could have occurred in two steps. In the first stage, shallow, meteoric fluids affect primary, unaltered BIF by simultaneously oxidizing magnetite to martite and replacing quartz with hydrous iron oxides. In the second stage of supergene processes, deep burial upgrades the hydrous iron oxides to microplaty hematite. Removal of silica from BIF and successive precipitation of iron resulted in the formation of martite- goethite ore. Soft laminated ores were formed where precipitation of iron was partial or absent. The leached out space remains with time and the interstitial space is generally filled

  19. The Gas Hills uranium district and some probable controls for ore deposition

    USGS Publications Warehouse

    Zeller, Howard Davis

    1957-01-01

    Uranium deposits occur in the upper coarse-grained facies of the Wind River formation of Eocene age in the Gas Hills district of the southern part of the Wind River Basin. Some of the principal deposits lie below the water table in the unoxidized zone and consist of uraninite and coffinite occurring as interstitial fillings in irregular blanket-like bodies. In the near-surface deposits that lie above the water table, the common yellow uranium minerals consist of uranium phosphates, silicates, and hydrous oxides. The black unoxidized uraninite -coffinite ores show enrichment of molybdenum, arsenic, and selenium when compared to the barren sandstone. Probable geologic controls for ore deposits include: 1) permeable sediments that allowed passage of ore-bearing solutions; 2) numerous faults that acted as impermeable barriers impounding the ore -bearing solutions; 3) locally abundant pyrite, carbonaceous material, and natuial gas containing hydrogen sulfide that might provide a favorable environment for precipitation of uranium. Field and laboratory evidence indicate that the uranium deposits in the Gas Hills district are very young and related to the post-Miocene to Pleistocene regional tilting to the south associated with the collapse of the Granite Mountains fault block. This may have stopped or reversed ground water movement from a northward (basinward) direction and alkaline ground water rich in carbonate could have carried the uranium into the favorable environment that induced precipitation.

  20. Ore-forming processes in the Drazhnoe gold-quartz deposit (Eastern Yakutia, Russia)

    NASA Astrophysics Data System (ADS)

    Aristov, V. V.; Prokofiev, V. Yu.; Imamendinov, B. N.; Kryazhev, S. G.; Alekseev, V. Yu.; Sidorov, A. A.

    2015-09-01

    Themobarogeochemical investigations revealed that quartz from the Drazhnoe deposit was formed in mesothermal conditions at depths of 3-4 km from carbon dioxide-water fluids with wide salinity variations and an admixture of methane. Several types of fluids are distinguishable on the basis of the composition of extracts: hydrocarbonate-sodium, highly diluted, and late sulfate-hydrocarbonate-sodium with elevated salinity. Ore minerals precipitated in the thermostatic environments against the background of fluid heterogenization due to a probably significant pressure drop and mixing of different solutions. Metamorphic processes related to the early collision stage provided no substantial impact on the composition and potential of gold ore mineralization.

  1. Magmatic Conduit Metallogenic System - A New Model for the Origin of Ore-deposits

    NASA Astrophysics Data System (ADS)

    Su, S.; Tang, Z.; Wu, G.; Deng, J.; Xiao, Q.; Luo, Z.; Cui, Y.

    2013-12-01

    Origin and emplacement processes of ore-deposits connected with intrusions remains poorly understood. Here we propose a new model 'Magmatic Conduit Metallogenic System' to explain the origin of ore-deposits. Magmatic flow (or Melt-fluid flow) bearing metals will finally settle in the conduits at later stage of magma evolved in magma metallogenic system. Magmatic flow (or Melt-fluid flow) bearing metals include many types, such as sulfide melts and iron melts bearing fluids. Conduits will form along the zones of structural weakness, such as fault zone and interface of two different types of rocks. These conduits are usually very complicated in the magmatic system, exemplified by two typical ore-deposits, detailed as follows. The Jinchuan sulfide deposit, located in Gansu Province, China, is the third largest magmatic Cu-Ni Platinum Group Elements (PGE) in the world. There are mainly four orebodies (orebody 58, 24, 1, and 2) from west to east, with Ni/Cu value at 1.24, 1.56, 1.83 and 2.06 respectively; the content of Pt+Pd ranges from 0.4 to 10.3 ppm, with the highest value occurs in the west. This suggests that the direction of the melt flow bearing sulfide is from west to east and the front of the conduit system is in the east part of the deposit. Sulfide segregation in the magmatic chamber or in the conduits might have caused ore content to change in different part of the conduit systems. Another typical example is the Xishimen iron deposit, which is located in the South of Hebei Province, China. It has been considered as a skarn-type iron deposit conventionally. However, many geological evidence suggests that Xishimen iron deposit is a magmatic iron deposit instead. Such evidence includes: 1. The boundaries between iron orebodies and country rocks are obvious, no transitional relationship; 2. Iron ore body injected into the country rocks (including genesis, diorite, and marble); 3. There are some vesicular in the iron ores; 4. Magnetite as an interstitial mineral

  2. Sm-Nd evidence for the age and origin of a Mississippi Valley Type ore deposit.

    PubMed

    Halliday, A N; Shepherd, T J; Dickin, A P; Chesley, J T

    1990-03-01

    MISSISSIPPI Valley Type (MVT) ore deposits represent the relatively common product of large-scale fluid transport in the continental lithosphere, yet the models for their genesis have been more controversial and unconstrained than those of any other class of giant ore deposit(1,2). Here we show that Sm-Nd isotope data can be used to determine the age and origin of an MVT deposit. Sm-Nd data for fluorites from the North Pennine orefield are difficult to explain unless some of the mineralization is of Mesozoic rather than the traditionally accepted Palaeozoic age. Furthermore, the Nd and Sr isotopie compositions of the fluorites do not support a variety of recent models that include derivation of the components from the mantle, the Lower Palaeozoic basement or the underlying buried granite which served to focus the flow of hydrothermal fluids.

  3. Sm-Nd evidence for the age and origin of a Mississippi Valley Type ore deposit.

    PubMed

    Halliday, A N; Shepherd, T J; Dickin, A P; Chesley, J T

    1990-03-01

    MISSISSIPPI Valley Type (MVT) ore deposits represent the relatively common product of large-scale fluid transport in the continental lithosphere, yet the models for their genesis have been more controversial and unconstrained than those of any other class of giant ore deposit(1,2). Here we show that Sm-Nd isotope data can be used to determine the age and origin of an MVT deposit. Sm-Nd data for fluorites from the North Pennine orefield are difficult to explain unless some of the mineralization is of Mesozoic rather than the traditionally accepted Palaeozoic age. Furthermore, the Nd and Sr isotopie compositions of the fluorites do not support a variety of recent models that include derivation of the components from the mantle, the Lower Palaeozoic basement or the underlying buried granite which served to focus the flow of hydrothermal fluids. PMID:18278025

  4. REE Mineralization in Kiruna-type Magnetite-Apatite Ore Deposits: Magmatism and Metasomatism

    NASA Astrophysics Data System (ADS)

    Harlov, D. E.

    2015-12-01

    ,K)Cl) fluids originating in the surrounding country rock or as fluids associated with metamorphic events such as regional albitization or actinolization. The abundance of (Y+REE)-bearing minerals in these deposits suggests that in addition to being mined for their Fe ore, they could also be economically mined for (Y+REE) as well.

  5. Prospecting For Magnetite Ore Deposits With A Innovative Sensor's of Unique Fundamentally New Magnetometer.

    NASA Astrophysics Data System (ADS)

    Emelianenko, T. I.; Tachaytdinov, R. S.; Sarichev, V. F.; Kotov, B. V.; Susoeva, G. N.

    After careful study of principles and abilities of all existing magnetmeters of all three revolutions in magnetic prospecting we have come to the conclusion that they cannot solve local guestions of the magnetic prospecting or determine centre coordinates of magnetite ore body before drilling Electromagnetism lows and achievents magnetprospectings and radioelectronics of all 20th century serve as a theoretical base of the "locator". While creating this cardinally new magnetmeter , we borrowed different things from radio-prospectors, magnetprospectors, wireless operators and combined all of them while creating the "locators''. The "locators' construction is bas ed on the "magnetic intensification" principle ,owing to which this "locators" are characterised by hight sensitiveness and ability to determine centers of even little commercial magnetite ore deposits with relatively weak magnetic anomalies. The main advantage of the "locators" over existing ones is that it can solve local questions determine centre coordinates. A remarkably simple locator construction determine direction of the on-surface measurings towards the ore body centre and gives approximate prognosis resourses before/withour/ drilling. The "locators" were worked out for the first time in history , they have 2 licences. The fundamental design and drawbacks of the existing magnetometers have been inherited from the original magnetometre dating back two or three hundred years. The developers of the existing magnetometres have all gone along the same well- beaten track of replacing the primitive sensor in the form of a piece of ore hung on a string at first by an arrow sensor and later by magnetically oriented protons and quanta, with amplification of the sensors' OUTPUT signal. Furthermore, all the existing magnetometres are imperfect in that they, lacking the directivity of the ground-level magnetic measurements, only record the overall magnetic vector field generated by all the ore bodies around the

  6. The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

    2014-09-01

    The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ∼30 to ∼600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ∼200 to ∼500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and

  7. Evaluation of feasibility of static tests applied to Küre VMS ore deposits

    NASA Astrophysics Data System (ADS)

    Demirel, Cansu; Çelik Balci, Nurgül; Şeref Sönmez, M.

    2015-04-01

    Küre volcanogenic massive sulfide (VMS) ore deposits have been mined for its copper content for over centuries. However, there is no published data on AMD around Küre VMS ore deposits. This study investigates the sources of acid producing mechanisms in Küre, using field and laboratorial approaches. Geochemical static tests to predict AMD generation are widely applied to mining sites for assessing potential environmental consequences. However, there are well known limitations of these methods particularly resulting from assumptions used for calculations. To test the feasibility of the methods to predict potential of AMD generation of Küre (VMS) copper deposits, for the first time, acid production and neutralization potential of various mine wastes of Küre (VMS) copper deposits were determined. To test our static test results, in situ and laboratory geochemical data were also obtained from the groundwater discharges from Bakibaba underground mining tunnels. Feasibility study showed that, despite a few inconsistencies, static tests were suitable for predicting generation of AMD around Küre copper mining site and reflected well the site conditions. The current study revealed that pulp density, defined as solid/liquid ratio and used for static tests, is an important limiting factor to predict reliable data for AMD generation. In this study, we also determined surface waters affected by AMD are predicted to have a pH value between 3 and 5, with an average of pH 4. Excessive concentrations of manganese, copper, cobalt and sulfate are also noted with considerable amounts of iron and zinc, which can reach to toxic levels. Moreover, iron and zinc were found to be the controlling the fate of metals by precipitation and co-precipitation, due to their relatively depleted concentrations at redox shifting zones. Key words: Küre pyritic copper ore, Bakibaba mining tunnels, volcanogenic massive sulfide ore deposits, acid production potential, neutralization potential

  8. Estyuninky's Deformation Characteristics of the Iron-Ore Deposit by Gravimetric Means

    NASA Astrophysics Data System (ADS)

    Vandysheva, Ksenya; Filatov, Vladimir

    2013-04-01

    Gravitation is the main energy source of many processes which happen in crust. Gravity possesses the leading role in structurization; it defines a tectonic broken state and permeability of the geological medium, having significant importance at an ore deposition. Because of the gravitation density naturally changes, permeability and other properties of the geological medium changes too. Presence in crust of density heterogeneity of a various form and the sizes and properties change, show its compound stress of deformation condition. Studying of the deformations caused by gravitation, represents great expected and research interest. Theoretical basis of studying of these deformations consists on ratios between components of a pure tensor deformation and its first invariant -dilatation and results of measurement of gravity force. The method of deformation studying of the geological medium, developed on this basis, was called a method of the tektonophysic analysis of a gravitational field (MTPAGF). The detailed analysis of results of MTPAGF was made for the region of the Estyuninsky iron-ore deposit. The deposit region is characterized by a reversed dilatation. The zero isoline of dilatation divides it into two parts. To the east of this isoline where there is a deposit, a dilatation positive and rather small size. To the west - a dilatation negative and it increases as approaching a protrusion. Thus, to the east of the zero isoline the geological medium is in stretching mode, which promote relative expansion of the medium, improvement of its permeability. Thanks to it favorable conditions for an ore deposition here were created. To the west f the zero isoline medium is in a compression mode. Therefore it is characterized by smaller permeability. The border of change of a sign of a dilatation probably was important a role of the peculiar deformation barrier blocking migration through it of ore substance. It is possible to make the following conclusion of the analysis

  9. Metallogeny of the Great Basin: crustal evolution, fluid flow, and ore deposits

    USGS Publications Warehouse

    Hofstra, Albert H.; Wallace, Alan R.

    2006-01-01

    The Great Basin physiographic province in the Western United States contains a diverse assortment of world-class ore deposits. It currently (2006) is the world's second leading producer of gold, contains large silver and base metal (Cu, Zn, Pb, Mo, W) deposits, a variety of other important metallic (Fe, Ni, Be, REE's, Hg, PGE) and industrial mineral (diatomite, barite, perlite, kaolinite, gallium) resources, as well as petroleum and geothermal energy resources. Ore deposits are most numerous and largest in size in linear mineral belts with complex geology. U.S. Geological Survey (USGS) scientists are in the final year of a research project initiated in the fall of 2001 to increase understanding of relations between crustal evolution, fluid flow, and ore deposits in the Great Basin. Because of its substantial past and current mineral production, this region has been the focus of numerous investigations over the past century and is the site of ongoing research by industry, academia, and state agencies. A variety of geoinformatic tools was used to organize, reinterpret, and display, in space and time, the large amounts of geologic, geophysical, geochemical, and hydrologic information deemed pertinent to this problem. This information, in combination with concentrated research on (1) critical aspects of the geologic history, (2) an area in northern Nevada that encompasses the major mineral belts, and (3) important mining districts and deposits, is producing new insights about the interplay between key tectonic events, hydrothermal fluid flow, and ore genesis in mineral belts. The results suggest that the Archean to Holocene history of the Great Basin was punctuated by several tectonic events that caused fluids of different origins (sea water, basinal brine, meteoric water, metamorphic water, magmatic water) to move through the crust. Basement faults reactivated during these events localized deformation, sedimentation, magmatism, and hydrothermal fluid flow in overlying

  10. Investigation of LANDSAT imagery on correlations between ore deposits and major shield structures in Finland

    NASA Technical Reports Server (NTRS)

    Tuominen, H. V. (Principal Investigator); Kuosmanen, V.

    1977-01-01

    The author has identified the following significant results. Several regional lineaments appear to correlate with the distribution of ore deposits and showings. Combined study of LANDSAT summer and winter mosaics and color composites of geological, geomorphological, and geophysical maps makes the correlation more perceptible. The revealed pattern of significant lineaments in northern Finland is fairly regular. The most significant lineaments seen in LANDSAT mosaics are not detectable in single images.

  11. The formation of ore mineral deposits on the Moon: A feasibility study

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Lu, Fengxiang

    1992-01-01

    Most of the ore deposits on Earth are the direct result of formation by hydrothermal solutions. Analogous mineral concentrations do not occur on the Moon, however, because of the absence of water. Stratified ore deposits form in layered instrusives on Earth due to fractional crystallization of magma and crystal settling of high-density minerals, particularly chromium in the mineral chromite. We have evaluated the possibility of such mineral deposition on the Moon, based upon considerations of 'particle settling velocities' in lunar vs. terrestrial magmas. A first approximation of Stoke's Law would seem to indicate that the lower lunar gravity (1/6 terrestrial) would result in slower crystal settling on the Moon. However, the viscosity of the silicate melt is the most important factor affecting the settling velocity. The viscosities of typical lunar basaltic melts are 10-100 times less than their terrestrial analogs. These lower viscosities result from two factors: (1) lunar basaltic melts are typically higher in FeO and lower in Al2O3, Na2O, and K2O than terrestrial melts; and (2) lunar igneous melts and phase equilibria tend to be 100-150 C higher than terrestrial, largely because of the general paucity of water and other volatile phases on the Moon. Therefore, particle settling velocities on the Moon are 5-10 times greater than those on Earth. It is highly probable that stratiform ore deposits similar to those on Earth exist on the Moon. The most likely ore minerals involved are chromite, ilmenite, and native FeNi metal. In addition, the greater settling velocities of periodotite in lunar magmas indicate that the buoyancy effects of the melt are less than on Earth. Consequently, the possibility is considerably less than on Earth of deep-seated volcanism transporting upper mantle/lower crustal xenoliths to the surface of the Moon, such as occurs in kimberlites on Earth.

  12. Geology and ore deposits of the Pioche district, Nevada

    USGS Publications Warehouse

    Westgate, L.G.; Knopf, Adolph

    1932-01-01

    LOCATION AND SURFACE FEATURES The Bristol Range, Highland, and Ely Range quadrangles make up the larger part of a. rectangular area 35 miles north and south by 24 miles east and west, which lies 19 miles west of the Nevada-Utah line and about 250 miles southwest of Salt Lake City. The district lies within the Great Basin, a semiarid region of alternating mountain ranges and intermontane plains floored largely by outwash from the mountains. The plain, which slopes away from the ranges, stands between 4,700 and 6,000 feet above the sea. The Bristol and Highland Ranges, which are separated only by a low gap, form an almost continuous north-south range that rises about 2,500 feet above the highest part of the surrounding plain, to general altitudes of 8,000 to 9,000 feet, though the highest point, Highland Peak, reaches 9,395 feet. A lower range, the Ely Range, with a northwesterly trend, lies farther east and nearly in touch with the Bristol-Highland Range. The town of Pioche lies midway on the. eastern foot of the Ely Range. ROOKS OF THE PIOOHB REGION The rocks of the ranges are Paleozoic sediments, Tertiary (?) lavas and intrusive rocks, and Pliocene (?) tuffs. The Paleozoic sediments have a total thickness of nearly 18,000 feet. Over 8,000 feet of the Cambrian has been measured without reaching its base. The lowest Cambrian formation is a quartzite, of which only the upper 1,500 feet is exposed, and this is followed by 1,200 feet of shale, 400 feet of limestone, aoid 150 feet of shale. Above this second shale the upper three-fourths of the Cambrian consists of limestone and dolomitic limestone. It is in the quartzite and in the limestone interbedded in and bounding the shales that the main ore bodies of the district have been found. Above the Cambrian comes 1,795 feet of Ordovician limestone, with some interbedded dolomite and with a 50-foot quartzite a, third of the way down from the top; 75 feet of Silurian dolomite; 3,000 feet of Middle Devonian dolomite with

  13. Multiple origin of the `Kniest feeder zone' of the stratiform Zn-Pb-Cu ore deposit of Rammelsberg, Germany

    NASA Astrophysics Data System (ADS)

    Muchez, Philippe; Stassen, Peter

    2006-05-01

    The Zn-Pb-Cu ore deposit of Rammelsberg is characterized by a complex fluid flow history. The main phase of ore deposition occurred during the Middle Devonian in the Rhenohercynian basin. The Kniest zone underlying the stratiform ore is interpreted as the feeder zone, along which hydrothermal fluids migrated upward and were expelled on the sea floor. Mineralizing brines possibly had a minimum temperature of 130°C, and salinity ranged between 4.9 and 10.3 eq. wt.% NaCl. The ore and its host rock became folded during the Variscan orogeny, and low salinity fluids (1.0 to 2.3 eq. wt.% NaCl) were mobilized during this tectonic period. Remobilization of the ore took place during the Mesozoic by a high salinity (17.3 to 20.2 eq. wt.% NaCl) H2O-NaCl-CaCl2 fluid.

  14. Manganese deposits in northeastern European Russia and the Urals: Isotope geochemistry, genesis, and evolution of ore formation

    NASA Astrophysics Data System (ADS)

    Kuleshov, V. N.; Brusnitsyn, A. I.; Starikova, E. V.

    2014-09-01

    Based on new data on the lithology, mineralogy, chemistry, and isotopic composition of manganese carbonate ores and rocks at the deposits and occurrences in the Novaya Zemlya Archipelago, the Pai-Khoi, and the Urals, as well as using data from the literature, the main Phanerozoic basins of manganese deposition have been established in the geological history of Laurasia, Pangea, and Siberian paleocontinents. The formation conditions of manganese ore gradually changed from hydrothermal-sedimentary in the Middle Paleozoic to sedimentary-diagenetic in Mesozoic and Cenozoic. The ore was also formed under catagenetic conditions. Carbon of oxidized organic matter plays a substantial role in the formation of manganese carbonates.

  15. Characterization of U ore from a roll-front U deposit: Implications of dominant U-Ti mineral for ore genesis and post solution-mining U immobilization

    NASA Astrophysics Data System (ADS)

    Brown, S. T.; Basu, A.; Christensen, J. N.; Reimus, P. W.; Heikoop, J. M.; WoldeGabriel, G. W.; Hartmann, M.; DePaolo, D. J.

    2015-12-01

    Reductive immobilization of dissolved U(VI) is an important process that gives rise to roll-front U deposits as well as offers a remediation strategy after in situ recovery (ISR) mining of roll-fronts by oxidative dissolution of the U ore. About 25% of the global and over 90% of all U resources in the United States consist of roll-front deposits. Accordingly, ~50% of global U mining and almost all current U mining in the United States is ISR mining. Therefore, it is important to identify the U immobilization pathways for an improved understanding of the U ore genesis and postmining U(VI) remediation. Here, we characterize (XRD, XRF, SEM/EDS, QEMSCAN) the U ore from a roll-front U deposit and sediments downgradient of the ore from an ISR site at Rosita, TX, USA. The dominant U mineral in Rosita U ore is brannerite (nominally U4+Ti2O6, up to 0.032 wt%), followed by coffinite and U-oxides. The U mineralized sand is composed of quartz (41-53%), calcite (15-30%), plagioclase (11-19%), microcline (2-9%), clinoptilolite (0.5-7%) with minor amounts of pyrite/marcasite (2-7%) and clays/micas (1-4%), and very little organic C (<0.1%). Ore zone samples contain minor amounts (<2%) of hematite, V-oxides/V-Ti-Fe-oxides and sulfidized Fe-Ti oxides with variable Fe, Ti and S ratios locally hosting low levels of U. The dominant sulfide mineral is marcasite. We observe a complex relationship between U-Ti minerals and sulfide/silicate phases where U minerals occur as inclusions, irregularly developed veins or intergrowths. Except for the U concentrations, the downgradient sediments are compositionally similar to the ore and contain abundant smectite/illite (7-45%). The predominance of brannerite implies direct reduction of U(VI) on surfaces of reduced Fe-Ti oxides as a major ore-forming mechanism. Our results reveal an as yet unidentified mechanism of ore genesis that differs from the current model that presupposes the sulfidized Fe-Ti oxides as the main reductant of U

  16. Origin of high-grade gold ore, source of ore fluid components, and genesis of the Meikle and neighboring Carlin-type deposits, Northern Carlin Trend, Nevada

    USGS Publications Warehouse

    Emsbo, P.; Hofstra, A.H.; Lauha, E.A.; Griffin, G.L.; Hutchinson, R.W.

    2003-01-01

    The Meikle mine exploits one of the world's highest grade Carlin-type gold deposits with reserves of ca. 220 t gold at an average grade of 24.7 g/t. Locally, gold grades exceed 400 g/t. Several geologic events converged at Meikle to create these spectacular gold grades. Prior to mineralization, a Devonian hydrothermal system altered the Bootstrap limestone to Fe-rich dolomite. Subsequently the rocks were brecciated by faulting and Late Jurassic intrusive activity. The resulting permeability focused flow of late Eocene Carlin-type ore fluids and allowed them to react with the Fe-rich dolomite. Fluid inclusion data and mineral assemblages indicate that these fluids were hot (ca. 220??C),of moderate salinity (400 g/t. Petrographic observations, geochemical data, and stable isotope results from the Meikle mine and other deposits at the Goldstrike mine place important constraints on genetic models for Meikle and other Carlin-type gold deposits on the northern Carlin trend. The ore fluids were meteoric water (??D = -135???, ??18O = -5???) that interacted with sedimentary rocks at a water/rock ratio of ca. 1 and temperatures of ca. 220??C. The absence of significant silicification suggests that there was little cooling of the ore fluids during mineralization. These two observations strongly suggest that ore fluids were not derived from deep sources but instead flowed parallel to isotherms. The gold was transported by H2S (??34S = 9???), which was derived from Paleozoic sedimentary rocks. The presence of auriferous sedimentary exhalative mineralization in the local stratigraphic sequence raises the possibility that preexisting concentrations of gold contributed to the Carlin-type deposits. Taken together our observations suggest that meteoric water evolved to become an ore fluid by shallow circulation through previously gold- and sulfur-enriched rocks. Carlin-type gold deposits formed where these fluids encountered permeable, reactive Fe-rich rocks.

  17. Geology and Ore Deposits of the Uncompahgre (Ouray) Mining District, Southwestern Colorado

    USGS Publications Warehouse

    Burbank, Wilbur Swett; Luedke, Robert G.

    2008-01-01

    The Uncompahgre mining district, part of the Ouray mining district, includes an area of about 15 square miles (mi2) on the northwestern flank of the San Juan Mountains in southwestern Colorado from which ores of gold, silver, copper, lead, and zinc have had a gross value of $14 to 15 million. Bedrock within the district ranges in age from Proterozoic to Cenozoic. The oldest or basement rocks, the Uncompahgre Formation of Proterozoic age, consist of metamorphic quartzite and slate and are exposed in a small erosional window in the southern part of the district. Overlying those rocks with a profound angular unconformity are Paleozoic marine sedimentary rocks consisting mostly of limestones and dolomites and some shale and sandstone that are assigned to the Elbert Formation and Ouray Limestone, both of Devonian age, and the Leadville Limestone of Mississippian age. These units are, in turn, overlain by rocks of marine transitional to continental origin that are assigned to the Molas and Hermosa Formations of Pennsylvanian age and the Cutler Formation of Permian age; these three formations are composed predominantly of conglomerates, sandstones, and shales that contain interbedded fossiliferous limestones within the lower two-thirds of the sequence. The overlying Mesozoic strata rest also on a pronounced angular unconformity upon the Paleozoic section. This thick Mesozoic section, of which much of the upper part was eroded before the region was covered by rocks of Tertiary age, consists of the Dolores Formation of Triassic age, the Entrada Sandstone, Wanakah Formation, and Morrison Formation all of Jurassic age, and the Dakota Sandstone and Mancos Shale of Cretaceous age. These strata dominantly consist of shales, mudstones, and sandstones and minor limestones, breccias, and conglomerates. In early Tertiary time the region was beveled by erosion and then covered by a thick deposit of volcanic rocks of mid-Tertiary age. These volcanic rocks, assigned to the San Juan

  18. The world-class Jinding Zn-Pb deposit: ore formation in an evaporite dome, Lanping Basin, Yunnan, China

    NASA Astrophysics Data System (ADS)

    Leach, David L.; Song, Yu-Cai; Hou, Zeng-Qian

    2016-07-01

    The Jinding Zn-Pb sediment-hosted deposit in western Yunnan, China, is the fourth largest Zn deposit in Asia. Based on field observations of the ore textures, breccias, and the sandstone host rocks, the ores formed in a dome that was created by the diapiric migration of evaporites in the Lanping Basin during Paleogene deformation and thrust loading. Most of the ore occurs in sandstones that are interpreted to be a former evaporite glacier containing a mélange of extruded diapiric material, including breccias, fluidized sand, and evaporites that mixed with sediment from a fluvial sandstone system. A pre-ore hydrocarbon and reduced sulfur reservoir formed in the evaporite glacier that became the chemical sink for Zn and Pb in a crustal-derived metalliferous fluid. In stark contrast to previous models, the Jinding deposit does not define a unique class of ore deposits; rather, it should be classified as MVT sub-type hosted in a diapiric environment. Given that Jinding is a world-class ore body, this new interpretation elevates the exploration potential for Zn-Pb deposit in other diapir regions in the world.

  19. Seeking the mantle contribution for the formation of giant ore deposits: Contemporaneous alkaline lamproites and carbonatites in the Kalmakyr and Muruntau ore districts, Tienshan, Uzbekistan

    NASA Astrophysics Data System (ADS)

    Seltmann, Reimar; Choulet, Flavien

    2014-05-01

    The decline in discoveries of ore deposits contrasted by the rising demand for e-tech metals requires the global mining industry to continuously seek innovation in exploration. Unravelling the source of metals is among the crucial questions in exploration targeting and geologists have often had to recourse to indirect determinations based on the nature of the magma conveying the metals. The relative contributions of mantle and crust in metallogenic processes and the origin of the magmas from either shallow or deep mantle are not fully understood in the current models of ore genesis. To help to resolve this dilemma, research must establish the link between anorogenic (within-plate) and orogenic processes by using a holistic approach featuring crustal processes, mantle dynamics and crust-mantle interactions that may contribute to the magma fertilization. To achieve this, our study focuses on indicators for the involvement of deep-mantle intrusions (lamproites, lamprophyres, etc.), which have the potential to encapsulate pristine samples of the mantle (xenoliths) during magma ascent [1,2]. The Tienshan belt hosting many giant ore deposits is quite exemplary for understanding mantle-crust interactions and identifying the nature of mantle contribution to ore systems. Sr-Nd-Hf-Pb isotope systematics on granitoids [3] showed a variation of crustal to mixed signatures, indicating involvement of both older crustal sources and mantle-derived material, but the mantle source is not clearly assessed. As objects for our case study in Uzbekistan we choose the Kalmakyr Cu-Au porphyry deposit (~ 315 Ma; Chatkal-Kurama continental arc of Middle Tienshan) and the Muruntau orogenic Au deposit (~290 Ma, Turkestan-Alai / Kyzylkum accretionary complex of South Tienshan) to investigate the impact of associated alkaline magmas on the ore-bearing intrusions and mineralization. Field observations and geochronological data shed light on the spatial and temporal relationships between the

  20. Gold in Magmatic Hydrothermal Solutions and the Rapid Formation of a Giant Ore Deposit

    NASA Astrophysics Data System (ADS)

    Simmons, Stuart F.; Brown, Kevin L.

    2006-10-01

    The Ladolam hydrothermal system, on Lihir Island, Papua New Guinea, hosts one of the youngest and largest gold deposits in the world. Several deep (more than 1 kilometer) geothermal wells were drilled beneath the ore bodies to extract water at >275°C and to facilitate open-pit mining. Using a titanium down-hole sampler, we determined that the deep geothermal brine of magmatic origin contains ~15 parts per billion gold. At the current gold flux of 24 kilograms per year, this deposit could have formed within ~55,000 years. The combination of sustained metal flux and efficient metal precipitation led to the formation of a giant hydrothermal gold deposit in a short period.

  1. Gold in magmatic hydrothermal solutions and the rapid formation of a giant ore deposit.

    PubMed

    Simmons, Stuart F; Brown, Kevin L

    2006-10-13

    The Ladolam hydrothermal system, on Lihir Island, Papua New Guinea, hosts one of the youngest and largest gold deposits in the world. Several deep (more than 1 kilometer) geothermal wells were drilled beneath the ore bodies to extract water at >275 degrees C and to facilitate open-pit mining. Using a titanium down-hole sampler, we determined that the deep geothermal brine of magmatic origin contains approximately 15 parts per billion gold. At the current gold flux of 24 kilograms per year, this deposit could have formed within approximately 55,000 years. The combination of sustained metal flux and efficient metal precipitation led to the formation of a giant hydrothermal gold deposit in a short period. PMID:17038619

  2. Age of uranium ores at Ranger and Jabiluka unconformity vein deposits, Northern Territory, Australia

    SciTech Connect

    Ludwig, K.R.; Grauch, R.I.; Nutt, C.J.; Frishman, D.; Nash, J.T.; Simmons, K.R.

    1985-01-01

    The Ranger and Jabiluka uranium deposits are the largest in the Alligator Rivers Uranium Field (ARUF), which contains at least 20% of the world's low-cost uranium reserves. Ore occurs in early Proterozoic metasediments, below an unconformity with sandstones of the 1.65 Ga Kombolgie Formation. This study uses U-Pb isotope data from over 60 whole-rock drill core samples that contained a variety of mineral assemblages and textures. Data for Ranger samples indicate a well-defined age of 1.74 +/-.02 Ga. This 1.74 Ga age is distinctly pre-Kombolgie, so the Ranger deposit cannot have been formed by processes requiring its presence. This Ranger age is consistent, however, with mineralization related to heating associated with either the emplacement of early post-metamorphic granites, or possibly with intrusion of the nearby Oenpelli Dolerite. In contrast, data for the least-altered Jabiluka ores yield a concordia-intercept age of 1.44 +/-.02 Ga--significantly younger than the Ranger age, and also younger than the Komobolgie. This age may correspond to a regional thermal event, as indicated both by mafic dikes of roughly this age and a zircon lower-intercept age from a nearby granite-gneiss. Thus, together with the well-defined approx.900 Ma age of ores at the Nabarlek deposit, there are at least 3 distinct periods of major U-mineralization in the ARUF. Data for both Ranger and Jabiluka indicate the same, profound isotopic disturbance at some time in the interval of 0.4-0.6 Ga. Possibly this time corresponds to the development of basins and associated basalt flows to the W and SW, a suggested by Crick et. al. (1980).

  3. Automated recognition of stratigraphic marker shales from geophysical logs in iron ore deposits

    NASA Astrophysics Data System (ADS)

    Silversides, Katherine; Melkumyan, Arman; Wyman, Derek; Hatherly, Peter

    2015-04-01

    The mining of stratiform ore deposits requires a means of determining the location of stratigraphic boundaries. A variety of geophysical logs may provide the required data but, in the case of banded iron formation hosted iron ore deposits in the Hamersley Ranges of Western Australia, only one geophysical log type (natural gamma) is collected for this purpose. The information from these logs is currently processed by slow manual interpretation. In this paper we present an alternative method of automatically identifying recurring stratigraphic markers in natural gamma logs from multiple drill holes. Our approach is demonstrated using natural gamma geophysical logs that contain features corresponding to the presence of stratigraphically important marker shales. The host stratigraphic sequence is highly consistent throughout the Hamersley and the marker shales can therefore be used to identify the stratigraphic location of the banded iron formation (BIF) or BIF hosted ore. The marker shales are identified using Gaussian Processes (GP) trained by either manual or active learning methods and the results are compared to the existing geological interpretation. The manual method involves the user selecting the signatures for improving the library, whereas the active learning method uses the measure of uncertainty provided by the GP to select specific examples for the user to consider for addition. The results demonstrate that both GP methods can identify a feature, but the active learning approach has several benefits over the manual method. These benefits include greater accuracy in the identified signatures, faster library building, and an objective approach for selecting signatures that includes the full range of signatures across a deposit in the library. When using the active learning method, it was found that the current manual interpretation could be replaced in 78.4% of the holes with an accuracy of 95.7%.

  4. Chemical Equilibrium of the Dissolved Uranium in Groundwaters From a Spanish Uranium-Ore Deposit

    SciTech Connect

    Garralon, Antonio; Gomez, Paloma; Turrero, Maria Jesus; Buil, Belen; Sanchez, Lorenzo

    2007-07-01

    The main objectives of this work are to determine the hydrogeochemical evolution of an uranium ore and identify the main water/rock interaction processes that control the dissolved uranium content. The Mina Fe uranium-ore deposit is the most important and biggest mine worked in Spain. Sageras area is located at the north part of the Mina Fe, over the same ore deposit. The uranium deposit was not mined in Sageras and was only perturbed by the exploration activities performed 20 years ago. The studied area is located 10 Km northeast of Ciudad Rodrigo (Salamanca) at an altitude over 650 m.a.s.l. The uranium mineralization is related to faults affecting the metasediments of the Upper Proterozoic to Lower Cambrian schist-graywacke complex (CEG), located in the Centro-Iberian Zone of the Hesperian Massif . The primary uranium minerals are uraninite and coffinite but numerous secondary uranium minerals have been formed as a result of the weathering processes: yellow gummite, autunite, meta-autunite, torbernite, saleeite, uranotile, ianthinite and uranopilite. The water flow at regional scale is controlled by the topography. Recharge takes place mainly in the surrounding mountains (Sierra Pena de Francia) and discharge at fluvial courses, mainly Agueda and Yeltes rivers, boundaries S-NW and NE of the area, respectively. Deep flows (lower than 100 m depth) should be upwards due to the river vicinity, with flow directions towards the W, NW or N. In Sageras-Mina Fe there are more than 100 boreholes drilled to investigate the mineral resources of the deposit. 35 boreholes were selected in order to analyze the chemical composition of groundwaters based on their depth and situation around the uranium ore. Groundwater samples come from 50 to 150 m depth. The waters are classified as calcium-bicarbonate type waters, with a redox potential that indicates they are slightly reduced (values vary between 50 to -350 mV). The TOC varies between <0.1 and 4.0 mgC/L and the dissolved

  5. Alunite in the Pascua-Lama high-sulfidation deposit: Constraints on alteration and ore deposition using stable isotope geochemistry

    USGS Publications Warehouse

    Deyell, C.L.; Leonardson, R.; Rye, R.O.; Thompson, J.F.H.; Bissig, T.; Cooke, D.R.

    2005-01-01

    The Pascua-Lama high-sulfidation system, located in the El Indio-Pascua belt of Chile and Argentina, contains over 16 million ounces (Moz) Au and 585 Moz Ag. The deposit is hosted primarily in granite rocks of Triassic age with mineralization occurring in several discrete Miocene-age phreatomagmatic breccias and related fracture networks. The largest of these areas is Brecha Central, which is dominated by a mineralizing assemblage of alunite-pyrite-enargite and precious metals. Several stages of hydrothermal alteration related to mineralization are recognized, including all types of alunite-bearing advanced argillic assemblages (magmatic-hydrothermal, steam-heated, magmatic steam, and supergene). The occurrence of alunite throughout the paragenesis of this epithermal system is unusual and detailed radiometric, mineralogical, and stable isotope studies provide constraints on the timing and nature of alteration and mineralization of the alunite-pyiite-enargite assemblage in the deposit. Early (preore) alteration occurred prior to ca. 9 Ma and consists of intense silicic and advanced argillic assemblages with peripheral argillic and widespread propylitic zones. Alunite of this stage occurs as fine intergrowths of alunite-quartz ?? kaolinite, dickite, and pyrophyllite that selectively replaced feldspars in the host rock. Stable isotope systematics suggest a magmatic-hydrothermal origin with a dominantly magmatic fluid source. Alunite is coeval with the main stage of Au-Ag-Cu mineralization (alunite-pyrite-enargite assemblage ore), which has been dated at approximately 8.8 Ma. Ore-stage alunite has an isotopic signature similar to preore alunite, and ?? 34Salun-py data indicate depositional temperatures of 245?? to 305??C. The ??D and ?? 18O data exclude significant involvement of meteoric water during mineralization and indicate that the assemblage formed from H2S-dominated magmatic fluids. Thick steam-heated alteration zones are preserved at the highest elevations in

  6. Tectonophysics of hydrothermal ore formation: an example of the Antei Mo-U deposit, Transbaikalia

    NASA Astrophysics Data System (ADS)

    Petrov, V. A.; Rebetsky, Yu. L.; Poluektov, V. V.; Burmistrov, A. A.

    2015-07-01

    The Antei deposit of the southeastern Transbaikalian region is one of the largest uranium mines in Russia. It is hosted by the Late Paleozoic granitic basement of the Streltsovskaya caldera and was formed as a result of Late Mesozoic tectonothermal activity. Vein and stockwork-disseminated molybdenum-uranium mineralization at this deposit is controlled by zones of intense hydrothermal alteration, cataclasis, brecciation, and intense fracturing along steeply dipping faults, which acted as conduits for mineralizing fluids and hosts to the ore bodies. The upper edge of the ore-bearing zone is located at a depth of 400 m, and its lower edge was intersected at a depth of 1300 m from the day surface. The conditions of ore localization were determined using structural-geological and petrophysical studies coupled with numerical modeling of the effects of gravitational body forces at purely elastic and postcritical elastoplastic deformational stages. The dynamics of the tectonic stress field in the rock massif was reconstructed using the results of mapping of morphogenetic and kinematic characteristics of fault and fracture systems, as well as data on petrography and mineralogy of rocks and vein-filling material. It was shown that the fault framework of the deposit was formed in four tectonic stages, three of which took place in the geologic past and one of which reflects recent geologic history. Each tectonic stage was characterized by different parameters of the tectonic stress-strain field, fault kinematics, and conditions of mineral formation. The following types of metasomatic rocks are recognized within the deposit: high-temperature K-feldspar rocks and albitites (formed during the Late Paleozoic as the primary structural elements of a granitic massif) and Late Mesozoic low-temperature preore (hydromicatized rocks), synore (hematite, albite, chlorite, and quartz) and postore (kaolinite-smectite) rocks. The following petrophysical parameters were determined for all

  7. 3D Geological Model of Nihe ore deposit Constrained by Gravity and Magnetic Modeling

    NASA Astrophysics Data System (ADS)

    Qi, Guang; Yan, Jiayong; Lv, Qingtan; Zhao, Jinhua

    2016-04-01

    We present a case study on using integrated geologic model in mineral exploration at depth. Nihe ore deposit in Anhui Province, is deep hidden ore deposit which was discovered in recent years, this finding is the major driving force of deep mineral exploration work in Luzong. Building 3D elaborate geological model has the important significance for prospecting to deep or surround in this area, and can help us better understand the metallogenic law and ore-controlling regularity. A 3D geological model, extending a depth from +200m to -1500m in Nihe ore deposit, has been compiled from surface geological map, cross-section, borehole logs and amounts of geological inference. And then the 3D geological models have been given physical property parameter for calculating the potential field. Modelling the potential response is proposed as means of evaluating the viability of the 3D geological models, and the evidence of making small changes to the uncertain parts of the original 3D geological models. It is expected that the final models not only reproduce supplied prior geological knowledge, but also explain the observed geophysical data. The workflow used to develop the 3D geologic model in this study includes the three major steps, as follows: (1) Determine the basic information of Model: Defining the 3D limits of the model area, the basic geological and structural unit, and the tectonic contact relations and the sedimentary sequences between these units. (2) 3D model construction: Firstly, a series of 2D geological cross sections over the model area are built by using all kinds of prior information, including surface geology, borehole data, seismic sections, and local geologists' knowledge and intuition. Lastly, we put these sections into a 3D environment according to their profile locations to build a 3D model by using geostatistics method. (3) 3D gravity and magnetic modeling: we calculate the potential field responses of the 3D model, and compare the predicted and

  8. Understanding Cu release into environment from Kure massive sulfide ore deposits, Kastamonu, NW Turkey

    NASA Astrophysics Data System (ADS)

    Demirel, Cansu; Sonmez, Seref; Balci, Nurgul

    2014-05-01

    Covering a wide range on the earth's crust, oxidation of metal sulfide minerals have vital environmental impacts on the aquatic environment, causing one of the major environmental problems known as acid mine drainage (AMD). Located in the Kastamonu province of the Western Black Sea region, Kure district is one of the major copper mining sites in Turkey. Mining activities in the area heads back to ancient times, such that operation is thought to be started with the Roman Empire. Currently, only the underground mining tunnels of Bakibaba and Asikoy are being operated. Thus, mining heaps and ores of those pyritic deposits have been exposed to the oxidative conditions for so long. As a result of weathering processes of past and recent heaps of the Kure volcanic massive sulfide deposits in addition to the main ore mineral (chalcopyrite), significant amount of metals, especially Cu, are being released into the environment creating undesirable environmental conditions. In order to elucidate Cu release mechanisms from Kure pyritic ore deposits and mining wastes, field and laboratory approaches were used. Surface water and sediment samples from the streams around the mining and waste sites were collected. Groundwater samples from the active underground mining site were also collected. Physical parameters (pH, Eh, T°C, and EC) of water samples were determined in situ and in the laboratory using probes (WTW pH 3110, WTW Multi 9310 and CRISON CM 35). Metal and ion concentrations of the water samples were analysed using ICP-MS and DR 2800 spectrophotometer, respectively. High Cu, Co, Zn and Fe concentrations were determined in the water samples with pH values ranging from 2.9- 4. Cu concentrions ranges from 345 ppm to 36 ppm in the water samples. Consistent with the water samples, high Cu, Fe, Zn and Co were also determined in the sediment samples. Laboratory chalcopyrite oxidation experiments under the conditions representing the field site were set up as biological and

  9. Fluid mixing and ore deposition during the geodynamic evolution of the Sierra Almagrera (Betics, Spain)

    NASA Astrophysics Data System (ADS)

    Dyja, Vanessa; Tarantola, Alexandre; Hibsch, Christian; Boiron, Marie-Christine; Cathelineau, Michel

    2013-04-01

    Marine and continental intramountaineous basins developed during the Neogene orographic evolution of the Betico-rifan orogenic wedge, as well as the related uplifted ranges within the Sierra Almagrera Metamorphic Core Complexes (MCC). The NNE-SSW striking trans-Alboran transcurrent fault system crosscuts the MCC post-dating the extensional exhumation stages recorded in the metamorphic fabric. Iron ores (± Pb, Cu, Zn) are encountered either as stratabound ore deposits in the Neogene basins or as vein networks crosscutting the metamorphic fabric of graphitic phyllites from the Sierra Almagrera. These Late Miocene ore deposits are related to the activity of the N-S striking Palomares fault segment of the Trans-Alboran fault system. Three sets of quartz veins (Vα, Vαβ and Vβ) and one set of mineralized vein (Vγ, siderite, barite) are distinguished. The Vα and Vαβ respectively are totally or partially transposed into the foliation. The Vβ and Vγ veins are discordant to the foliation. The problem addressed in this study concerns the nature of the fluids involved in the metal deposits and their relationships with the main reservoir fluids, e.g. the deep metamorphic fluids, the basinal fluids, and eventually the recharge meteoric fluids. This study focuses thus on the evolution of the fluids at different stages of ductile-brittle exhumation of the metamorphic ranges (Sierras) and their role during the exhumation and later on in relation with the hydrothermalism and metal deposition at a regional scale. Paleofluids were studied as inclusions in quartz, siderite and barite from veins by microthermometry and Raman spectroscopy, and a stable isotope study is in progress. Earliest fluids recorded in (Vαβ) quartz veins are H2O- NaCl + CaCl2 (17 wt. %) - (traces of CO2, CH4, N2) metamorphic brines trapped at the ductile brittle transition at a minimum trapping temperatures (Th) of 340 °C. Older metamorphic fluids in (Vα) veins were lost during the complete

  10. Jasperoid float and stream cobbles as tools in geochemical exploration for hydrothermal ore deposits

    USGS Publications Warehouse

    Lovering, T.G.

    1981-01-01

    Fragments of silicified rocks that are associated with deposits of base and precious metals may be transported as cobbles and pebbles in alluvium far downstream from the source outcrop. These rocks commonly exhibit certain characteristics which distinguish them from other detrital siliceous material, and may thus serve as a useful tool in reconnaissance geochemical exploration. The predominant characteristics of jasperoid samples, classified according to genesis, type of host rock, and proximity to base and precious metal deposits have been tabulated from a large master file containing descriptive and analytical information on jasperoid samples representing more than a hundred areas in the United States. Jasperoid that is genetically and spatially associated with ore deposits is generally dark gray or brown in color, brecciated, phaneritic, and vuggy. Jasperoids associated with lead and zinc deposits exhibit extensive halos of lead and silver anomalies, and more restricted zinc and gold anomalies. Those related to copper deposits show extensive copper, silver, and gold anomalies, and more restricted bismuth and molybdenum anomalies. Jasperoid related to gold deposits tends to exhibit extensive gold and silver anomalies and more restricted titanium, barium, vanadium, molybdenum, and rare-earth element anomalies. ?? 1981.

  11. Rock Magnetic and Oxide Microscopy Studies of two South American Iron-Ore Deposits

    NASA Astrophysics Data System (ADS)

    Alva-Valdivia, L. M.

    2005-05-01

    Microscopy and rock-magnetic studies of the iron oxide-ore and host rocks in the Cristales-Pleito Melon (Chile) and Jacupiranga (Brazil) deposits were carried out to characterize and compare the magnetic mineralogy and the processes that affected the natural remanent magnetization (NRM) during emplacement and evolution of the iron-ore deposits. The microscopy study under reflected light shows that magnetic carriers are mainly magnetites, with minor amounts of ilmenite-hematite minerals. Titanomagnetite, shows trellis texture, which is compatible with high temperature oxy-exsolution processes. Grain sizes range from a few microns to >100 µm, and dominant magnetic state pseudo-single-domain, in agreement with hysteresis measurements. Thermal spectra, continuous susceptibility measurements, and isothermal remanent magnetization (IRM) acquisition suggest a predominance of some spinels (titanomagnetite or titanomaghemite) with low-Ti content as magnetic carriers. These data help to investigate the magnetic domain states and the remanence acquisition processes, and to assess their significance as a source of magnetic anomalies.

  12. Lead Isotope Constraints on the Sources of Ore Metals in SW Mexican Deposits

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.

    2007-12-01

    Lead isotope ratios from mineral deposits in southern Mexico increase with distance from the trench from 206Pb/204Pb values between 18.597 and 18.650 in the coastal area to values between 18.712 and 19.069 approximately 800 km east from the trench. This variation has been attributed to increasing assimilation of radiogenic lead from the crust with increasing distance from the trench. New sampling was undertaken in this area to provide a clearer picture of the potential sources of ore metals in this arc system, and also, if possible, to examine whether ore metal sources differ among the proposed tectonostratigraphic exotic terranes of southern Mexico. New TIMS lead isotope analyses are presented for samples from the metamorphic basement rocks of the Guerrero Terrane, the Late Cretaceous clastic sedimentary rocks from the Upper Mesozoic Assemblage, and for mid-Cretaceous igneous rocks, as well as for samples from the Oligocene La Verde, Esmeralda, and El Malacate copper prospects. Whole rock samples of schist from the Jurassic-Cretaceous Arteaga Complex and phyllite and slate from the Tierra Caliente Complex contain radiogenic lead relative to bulk earth models, with 206Pb/204Pb ranging from 18.981-19.256. These values are substantially more radiogenic than published values of analyses of metagabbro and charnockite from the Grenvillian-age Oaxaca Terrane. Sedimentary rocks (sandstones, siltstones, and marls) belonging to the Huetamo Sequence have 206Pb/204Pb values ranging between 18.630 to 18.998, close to the published data for the sediments from IPOD-DSDP Sites 487 and 488, Cocos Plate. Whole rock analyses of igneous rocks (granodiorite) collected from La Verde and El Malacate have 206Pb/204Pb ranging from 18.764 to 18.989, clustering between the fields represented by the sedimentary and the metamorphic rocks, suggesting assimilation of lead from these components. Ore samples from La Verde and Esmeralda have 206Pb/204Pb between 18.685 and 18.731 and plot within

  13. Biogeometallurgical pre-mining characterization of ore deposits: an approach to increase sustainability in the mining process.

    PubMed

    Dold, Bernhard; Weibel, Leyla

    2013-11-01

    Based on the knowledge obtained from acid mine drainage formation in mine waste environments (tailings impoundments and waste rock dumps), a new methodology is applied to characterize new ore deposits before exploitation starts. This gives the opportunity to design optimized processes for metal recovery of the different mineral assemblages in an ore deposit and at the same time to minimize the environmental impact and costs downstream for mine waste management. Additionally, the whole economic potential is evaluated including strategic elements. The methodology integrates high-resolution geochemistry by sequential extractions and quantitative mineralogy in combination with kinetic bioleach tests. The produced data set allows to define biogeometallurgical units in the ore deposit and to predict the behavior of each element, economically or environmentally relevant, along the mining process.

  14. Geology and ore deposits of the Monument Valley area, Apache and Navajo counties, Arizona: Part II

    USGS Publications Warehouse

    Witkind, I.J.; Thaden, R.E.

    1958-01-01

    In 1951 and 1952, the U.S. Geological Survey conducted a program of uranium investigations and geologic mapping in the Monument Valley area, Apache and Navajo Counties, Ariz. About 700 square miles were mapped on the Navajo Indian Reservation. A resource appraisal of the area was an inherent part of the program, and is detailed in this report. Production of vanadium and uranium is from two areas, the Monument No. 1 mine area in Navajo County, and the Monument No. 2 mine area in Apache County. In the period 1942-53 about 200,300 tons of ore was produced from these two areas. This ore yielded about 1,700,000 pounds of U3O8 and about 6,500,000 pounds of V2O5. The grade ranged from 0.15 percent U3O8 to 0.60 percent U3O8, and from 0.38 percent V2O5 to 3.02 percent V2O5. The vanadium-uranium ratio is about 4:1. The ore deposits are composed principally of the hydrous calcium-uranium vanadate tyuyamunite in basal channel sediments of the Shinarump member off the Chinle formation. Four types of ore bodies are present: (1) rods, (2) tabular ore bodies, (3) corvusite-type ore bodies, and (4) rolls. The reserves of uranium- and vanadium-bearing material are classed as measured, indicated, inferred, and potential. The reserves are further divided into three grade classes for material 1 foot or more thick: (1) 0.10 percent U3O8 and 1.00 percent V2O5 and above; (2) 0.05 percent U3O8 and 0.50 percent V2O5 and less than 0.10 percent U3O8 and 1.00 percent V2O5; and (3) 0.01 percent U3O8 and 0.10 percent V2O5 and less than 0.05 percent U3O8 and 0.05 percent V2O5. Measured reserves as of June 1953, in the Monument Valley area, Arizona, (all in the Monument No. 2 mine) total about 36,000 tons. Indicated reserves in the first grade class amount to about 62,000 tons. In this same grade class inferred reserves total about 3,000,000 tons. In the second grade class indicated and inferred reserves amount to about 2,000,000 tons. Inferred reserves in the third grade class total about 345

  15. Variations in the uranium isotopic compositions of uranium ores from different types of uranium deposits

    NASA Astrophysics Data System (ADS)

    Uvarova, Yulia A.; Kyser, T. Kurt; Geagea, Majdi Lahd; Chipley, Don

    2014-12-01

    Variations in 238U/235U and 234U/238U ratios were measured in uranium minerals from a spectrum of uranium deposit types, as well as diagenetic phosphates in uranium-rich basins and peraluminous rhyolites and associated autunite mineralisation from Macusani Meseta, Peru. Mean δ238U values of uranium minerals relative to NBL CRM 112-A are 0.02‰ for metasomatic deposits, 0.16‰ for intrusive, 0.18‰ for calcrete, 0.18‰ for volcanic, 0.29‰ for quartz-pebble conglomerate, 0.29‰ for sandstone-hosted, 0.44‰ for unconformity-type, and 0.56‰ for vein, with a total range in δ238U values from -0.30‰ to 1.52‰. Uranium mineralisation associated with igneous systems, including low-temperature calcretes that are sourced from U-rich minerals in igneous systems, have low δ238U values of ca. 0.1‰, near those of their igneous sources, whereas uranium minerals in basin-hosted deposits have higher and more variable values. High-grade unconformity-related deposits have δ238U values around 0.2‰, whereas lower grade unconformity-type deposits in the Athabasca, Kombolgie and Otish basins have higher δ238U values. The δ234U values for most samples are around 0‰, in secular equilibrium, but some samples have δ234U values much lower or higher than 0‰ associated with addition or removal of 234U during the past 2.5 Ma. These δ238U and δ234U values suggest that there are at least two different mechanisms responsible for 238U/235U and 234U/238U variations. The 234U/238U disequilibria ratios indicate recent fluid interaction with the uranium minerals and preferential migration of 234U. Fractionation between 235U and 238U is a result of nuclear-field effects with enrichment of 238U in the reduced insoluble species (mostly UO2) and 235U in oxidised mobile species as uranyl ion, UO22+, and its complexes. Therefore, isotopic fractionation effects should be reflected in 238U/235U ratios in uranium ore minerals formed either by reduction of uranium to UO2 or chemical

  16. Lead-isotope study of the sulphide ore and alteration zone, Bleikvassli zinc-lead deposit, northern Norway

    NASA Astrophysics Data System (ADS)

    Skauli, H.; Bjørlykke, A.; Thorpe, R. I.

    1992-09-01

    The Bleikvassli Zn-Pb deposit is located in the Uppermost Allochthon of the northern Norwegian Caledonides and is enclosed in amphibolite facies, multiply deformed supracrustal rocks. The stratiform orebody occurs stratigraphically above a sequence of gneiss and amphibolite and below a thick carbonate unit. The orebody, spatially associated with a footwall microcline gneiss that contains as much as 12wt‰ K2O, occurs in the lower part of the Mine Sequence which also comprises (kyanite-) mica schist and quartzo-feldspathic to siliceous rocks. The host rock lithology and the metal content of the Bleikvassli orebody are consistent with a SEDEX origin of the deposit. Field relationships and chemistry suggest that the microcline gneiss represents a potassic alteration of pelitic sediments related to the ore-forming process. A 464 ± 22 Ma Rb-Sr isochron for the microcline gneiss is interpreted to be a metamorphic age resulting from resetting of the Rb-Sr isotopic system during the Caledonian orogeny. The U-Pb in the whole rock shows evidence of recent mobilization of uranium and a partial or total resetting of the system during peak metamorphism. As with most SEDEX deposits, the lead isotope composition of the Bleikvassli ore plots close to the orogen growth curve. The geological setting of the ore and the lead — isotope compositions of the galenas indicate a Cambrian age of mineralization. However, the slope of the lead isotope data indicate an age of about 1000 Ma, which is also a maximum age of ore deposition. The lead isotope data for the galena, in conjunction with the compositions of the microcline gneiss during peak metamorphism, support a model whereby the microcline rock was formed as an alteration product by the ore forming fluid and the initial lead isotope composition of the microcline rock was similar to that of the galenas during ore deposition.

  17. Rhenium in ores of the Mikheevskoe porphyry Cu-Mo deposit, South Urals

    NASA Astrophysics Data System (ADS)

    Plotinskaya, O. Yu.; Grabezhev, A. I.; Seltmann, R.

    2015-03-01

    The distribution of Re in ores of the Mikheevskoe Mo-Cu deposit in the South Urals is studied. It is established that the grade of Re in the ores usually does not exceed 0.5 g/t. A positive correlation between concentrations of Re and Mo (correlation coefficient 0.94), and Re and Cu (correlation coefficient 0.52) is found. EMPA of individual flakes of molybdenite showed that a Re content higher than the detection limit has been measured in most flakes studied, as a rule as high as 0.4-0.5 wt %, but occasionally reaching 1.34 wt %. Re within flakes of molybdenite is irregularly distributed. Patchy, linear, and concentric-zoned patterns of zones with elevated Re content (usually 0.5-1 wt % Re, sometimes higher) are found against the lower content (up to 0.2 wt % Re) that is regularly distributed within the flake. Later hydrothermal processes and mechanical deformation of flakes result in epigenetic Re redistribution in molybdenite that leads to homogenization of molybdenite composition and smoothing of primary pattern, or removal of Re from molybdenite.

  18. The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation

    USGS Publications Warehouse

    Goldfarb, R.J.; Ayuso, R.; Miller, M.L.; Ebert, S.W.; Marsh, E.E.; Petsel, S.A.; Miller, L.D.; Bradley, D.; Johnson, Chad; McClelland, W.

    2004-01-01

    The Donlin Creek gold deposit, southwestern Alaska, has an indicated and inferred resource of approximately 25 million ounces (Moz) Au at a cutoff grade of 1.5 g/t. The ca. 70 Ma deposit is hosted in the Late Cretaceous Kuskokwim flysch basin, which developed in the back part of the are region of an active continental margin, on previously accreted oceanic terranes and continental fragments. A hypabyssal, mainly rhyolitic to rhyodacitic, and commonly porphyritic, 8- ?? 3-km dike complex, part of a regional ca. 77 to 58 Ma magmatic arc, formed a structurally competent host for the mineralization. This deposit is subdivided into about one dozen distinct prospects, most of which consist of dense quartz ?? carbonate veinlet networks that fill north-northeast-striking extensional fractures in the northeast-trending igneous rocks. The sulfide mineral assemblage is dominated by arsenopyrite, pyrite, and, typically younger, stibnite; gold is refractory within the arsenopyrite. Sericitization, carbonatization, and suffidation were the main alteration processes. Fluid inclusion studies of the quartz that hosts the resource indicate dominantly aqueous ore fluids with also about 3 to 7 mol percent CO2 ?? CH4 and a few tenths to a few mole percent NaCl + KCl. The gold-bearing fluids were mainly homogeneously trapped at approximately 275?? to 300??C and at depths of 1 to 2 km. Some of the younger stibnite may have been deposited by late-stage aqueous fluids at lower temperature. Measured ??18O values for the gold-bearing quartz range between 11 and 25 per mil; the estimated ??18O fluid values range from 7 to 12 per mil, suggesting a mainly crustally derived fluid. A broad range of measured ??D values for hydrothermal micas, between -150 and -80 per mil, is suggestive of a contribution from devolatilization of organic matter and/or minor amounts of mixing with meteoric fluids. Gold-associated hydrothermal sulfide minerals are characterized by ??34S values mainly between -16 and

  19. A deposit model for Mississippi Valley-Type lead-zinc ores: Chapter A in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Leach, David L.; Taylor, Ryan D.; Fey, David L.; Diehl, Sharon F.; Saltus, Richard W.

    2010-01-01

    This report also describes the geoenvironmental characteristic of MVT deposits. The response of MVT ores in the supergene environment is buffered by their placement in carbonate host rocks which commonly results in near-neutral associated drainage water. The geoenvironmental features and anthropogenic mining effects presented in this report illustrates this important environmental aspect of MVT deposits which separates them from other deposit types (especially coal, VHMS, Cu-porphyry, SEDEX, acid-sulfate polymetallic vein).

  20. Precipitation of lead-zinc ores in the Mississippi Valley-type deposit at Treves, Cevennes region of southern France

    USGS Publications Warehouse

    Leach, D.; Macquar, J.-C.; Lagneau, V.; Leventhal, J.; Emsbo, P.; Premo, W.

    2006-01-01

    The Trèves zinc–lead deposit is one of several Mississippi Valley-type (MVT) deposits in the Cévennes region of southern France. Fluid inclusion studies show that the ore was deposited at temperatures between approximately 80 and 150°C from a brine that derived its salinity mainly from the evaporation of seawater past halite saturation. Lead isotope studies suggest that the metals were extracted from local basement rocks. Sulfur isotope data and studies of organic matter indicate that the reduced sulfur in the ores was derived from the reduction of Mesozoic marine sulfate by thermochemical sulfate reduction or bacterially mediated processes at a different time or place from ore deposition. The large range of δ34S values determined for the minerals in the deposit (12.2–19.2‰ for barite, 3.8–13.8‰ for sphalerite and galena, and 8.7 to −21.2‰ for pyrite), are best explained by the mixing of fluids containing different sources of sulfur. Geochemical reaction path calculations, based on quantitative fluid inclusion data and constrained by field observations, were used to evaluate possible precipitation mechanisms. The most important precipitation mechanism was probably the mixing of fluids containing different metal and reduced sulfur contents. Cooling, dilution, and changes in pH of the ore fluid probably played a minor role in the precipitation of ores. The optimum results that produced the most metal sulfide deposition with the least amount of fluid was the mixing of a fluid containing low amounts of reduced sulfur with a sulfur-rich, metal poor fluid. In this scenario, large amounts of sphalerite and galena are precipitated, together with smaller quantities of pyrite precipitated and dolomite dissolved. The relative amounts of metal precipitated and dolomite dissolved in this scenario agree with field observations that show only minor dolomite dissolution during ore deposition. The modeling results demonstrate the important control of the reduced

  1. Mineral-petrochemical wallrock alteration of rocks in Bericul gold-ore deposit (Kuznetsk Alatau)

    NASA Astrophysics Data System (ADS)

    Kucherenko, I.; Yuxuan, Zhang; Abramova, R.

    2015-11-01

    The distribution of mineral associations in near-veined zonal propylite-beresite metasomatic columns of mesothermal Bericul gold-ore deposit was analyzed. However, the polymineral composition in the inner (axial and adjacent with it rear) zones is inconsistent to the existing metasomatic column theoretical model. According to Korzhinskii metasomatic zoning theory, implied monomineral (quartz) and binary-mineral (quartz, sericite) compositions are characteristic of axial and rear zones, respectively. In common with above- mentioned facts, the zoning formation of differential component mobility is influenced by two additional factors: counter diffusion of components from fractured fluids into pores and diffusion mechanism of mass transfer it's from pores fluids into fractured of rock-fluid systems.

  2. Significance of oil-like hydrocarbons in metamorphic and ore-deposit rocks

    SciTech Connect

    Price, L.C.

    1996-10-01

    Carbonaceous rocks (0.7-45.0% carbon content) from both greenschist metamorphism and hydrothermal-ore deposition were solvent-extracted and the resulting extracts characterized by standard analyses. Blank runs showed no contamination from laboratory procedures. The recovered HCS are in low, but significant, concentrations (0.5-50 ppm, rock weight). Moreover, the composition of these HCS (including biomarkers) resemble that of mature crude oils and do not have the ultra-mature characteristics expected from their high temperature environs. This strongly suggests that HCS will survive in even higher-rank rocks. These data contradict petroleum-geochemical paradigm regarding an inferred thermal instability of HCS and also bear on natural gas origins (e.g. - the hypothesized cracking of oil to gas), rock-water-HC interactions, petroleum-geochemical models, and other related topics.

  3. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  4. Volatile element isotopes of submarine hydrothermal ore deposits in the Western Pacific

    NASA Astrophysics Data System (ADS)

    Sano, Y.; Ooki, M.; Kagoshima, T.; Lan, T. F.; Takahata, N.; Ishibashi, J. I.

    2015-12-01

    This report describes abundances and isotopic compositions of volatile element trapped in fluid inclusions of submarine hydrothermal ore deposits collected in Western Pacific subduction zones (Okinawa Trough, Izu-Bonin arc, Mariana Trough, and Lau Basin) together with those in Kuroko ore deposits in northeastern Japan. The helium isotopic composition of Okinawa Trough, 6.6±1.0 Ra is much smaller than that of Izu-Bonin samples, 8.4±0.5 Ra. Those of Mariana Trough samples are similar to those of the Okinawa Trough, whereas Lau Basin data are consistent with those of Izu-Bonin. These characteristics might reflect the tectonic setting of regions: the former is related to back-arc spreading or rifting with a sediment signature in a graben, although the latter is attributable to island-arc type magmatism and/or its influence to back-arc volcanism. Argon and nitrogen isotopes are also explainable according to a similar hypothesis, although carbon isotopes are not the discriminator of tectonics. Origins of carbon and nitrogen are estimated respectively by the δ13C-CO2/3He and δ15N-N2/36Ar diagrams. The sedimentary contributions of both carbon and nitrogen are larger in Okinawa and Mariana Troughs than in Izu-Bonin and Lau Basin, whereas Kuroko samples agree well with the latter. Carbon and nitrogen fluxes are again larger in the former than in the latter. The CO2/N2 flux ratio at Okinawa and Mariana Troughs is larger than that at Izu-Bonin and Lau Basin, although both are considerably larger than that at MOR, suggesting that the additional sedimentary component has a higher C/N ratio than the upper mantle value.

  5. Epithermal mineralization and ore controls of the Shasta Au-Ag deposit, Toodoggone District, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Thiersch, P. C.; Williams-Jones, A. E.; Clark, J. R.

    1997-01-01

    The Shasta gold-silver deposit, British Columbia, Canada, is an adularia-sericite-type epithermal deposit in which deposition of precious metals coincided with the transition of quartz- to calcite-dominant gangue. Mineralization is associated with stockwork-breccia zones in potassically altered dacitic lapilli tuffs and flows, and consists of pyrite, sphalerite, chalcopyrite, galena, acanthite, electrum and native silver. Pre- and post-ore veins consist solely of quartz and calcite, respectively. Fluid inclusion microthermometry indicates that ore minerals were deposited between 280 ° and 225 °C, from a relatively dilute hydrothermal fluid (˜1.5 wt.% NaCl equivalent). Abundant vapor-rich inclusions in ore-stage calcite are consistent with boiling. Oxygen and hydrogen isotopic data (δ18Ofluid = -1.5 to -4.1‰; δDfluid = -148 to -171‰) suggest that the fluid had a meteoric origin, but was 18O-enriched by interaction with volcanic wallrocks. Initial (˜280 °C) fluid pH and log f O2 conditions are estimated at 5.3 to 6.0, and -32.5 to -33 bar, respectively; during ore deposition, the fluid became more alkaline and oxidizing. Ore deposition at Shasta is attributed to localization of meteoric hydrothermal fluids by extensional faults; mineralization was controlled by boiling in response to hydraulic brecciation. Calcite and base metal sulfides precipitated due to the increase in pH that accompanied boiling, and the associated decrease in H2S concentration led to precipitation of gold and silver.

  6. Sulphur isotope constraints on formation conditions of the Luiswishi ore deposit, Democratic Republic of Congo (DRC)

    NASA Astrophysics Data System (ADS)

    Lerouge, C.; Cailteux, J.; Kampunzu, A. B.; Milesi, J. P.; Fléhoc, C.

    2005-07-01

    Luiswishi is a Congo-type Neoproterozoic sediment-hosted stratiform Cu-Co ore deposit of the Central Africa Copperbelt, located northwest of Lubumbashi (DRC). The ores form two main Cu-Co orebodies hosted by the Mines Subgroup, one in the lower part of the Kamoto Formation and the other at the base of the Dolomitic Shales Formation. Sulphides occur essentially as early parallel layers of chalcopyrite and carrolite, and secondarily as late stockwork sulphides cross-cutting the bedding and the early sulphide generation. Both types of stratiform and stockwork chalcopyrite and carrolite were systematically analyzed for sulphur isotopes, along the lithostratigraphic succession of the Mine Series. The quite similar δ 34S values of stratiform sulphides and late stockwork sulphides suggest an in situ recrystallization or a slight remobilization of stockwork sulphides without attainment of isotopic equilibrium between different sulphide phases (chalcopyrite and carrolite). The distribution of δ 34S values (-14.4‰ to +17.5‰) combined with the lithology indicates a strong stratigraphic control of the sulphur isotope signature, supporting bacterial sulphate reduction during early diagenesis of the host sediments, in a shallow marine to lacustrine environment. Petrological features combined with sulphur isotopic data of sulphides at Luiswishi and previous results on nodules of anhydrite in the Mine Series indicate a dominant seawater/lacustrine origin for sulphates, precluding a possible hydrothermal participation. The high positive δ 34S values of sulphides in the lower orebody at Luiswishi, hosted in massive chloritic-dolomitic siltite (known as Grey R.A.T.), fine-grained stratified dolostone (D.Strat.) and silicified-stromatolitic dolomites alternating with chloritic-dolomitic silty beds (R.S.F.), suggest that they were probably deposited during a period of regression in a basin cut off from seawater. The variations of δ 34S values (i.e. the decrease of δ 34S values

  7. Oxidation potential and state of some vanadium ores and the relation of woody material to their deposition

    USGS Publications Warehouse

    Pommer, Alfred Michael

    1956-01-01

    Oxidation potential studies with a multiple pH-potential recorder designed and constructed for this purpose demonstrated that some uranium-vanadium ores in the Colorado Plateau were in a reduced state when deposited. Any oxidation which took place occurred after deposition. Experimental and theoretical reducing studies on fresh wood, wood degraded by burial for 450 years, and lignite, indicate that such ores may have been deposited by reduction of oxidized vanadium solutions by woody material. A vanadium (III) mineral, V2O(OH)4, was prepared synthetically by reduction of a vanadium (V) solution with wood. This is the only reported synthesis of any reduced vanadium mineral by any method. It was shown that the origin of almost all vanadium deposits currently of commercial importance involves life processes and products.

  8. Geological and geochemical studies of the Shujiadian porphyry Cu deposit, Anhui Province, Eastern China: Implications for ore genesis

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Zhou, Taofa; Yuan, Feng; Fan, Yu; White, Noel C.; Lin, Fengjie

    2015-05-01

    Most porphyry deposits in the world occur in magmatic arc settings and are related to subduction of oceanic plates. A small proportion of porphyry deposits occur in intracontinental settings, however they are still poorly understood. Shujiadian, a newly-discovered porphyry Cu deposit, is located in the Middle-Lower Yangtze River Valley metallogenic belt and belongs to the intracontinental class. The deposit has classic alteration zones defined by a core of potassic alteration and local Ca-silicate alteration, which is overprinted by a feldspar-destructive alteration zone and cut by veins containing epidote and chlorite. Wallrocks of the deposit are unreactive quartz-rich sedimentary rocks. Three main paragenetic stages have been recognized based on petrographic observations; silicate stage, quartz-sulfide stage, and sulfide-carbonate stage. Quartz + pyrite + chalcopyrite ± molybdenite veins, and quartz + chalcopyrite + pyrite veins of the quartz-sulfide stage contribute most of the copper, and chalcopyrite + chlorite ± pyrite ± pyrrhotite ± quartz ± illite veins of the sulfide-carbonate stage also contribute part of the copper; all the mineralized veins are associated with feldspar-destructive alteration. Investigations on the fluid inclusions in Shujiadian indicate that the ore-forming fluids had four evolutionary episodes: immiscibility and overpressure in the silicate stage, boiling in the quartz-sulfide stage and mixing with meteoric water in the sulfide-carbonate stage. Sulfur and strontium isotope studies suggest that ore metals were mainly derived from magmatic-hydrothermal fluids, and combined with our study of fluid inclusions, we infer that decompression, changes in oxygen fugacity and sulfur content were the main factors that caused Cu precipitation. Compared with porphyry deposits in magmatic arc settings, there are some differences in the ore-bearing rock, alteration, and the composition of ore-forming fluids.

  9. Ore mineralogy and sulfur isotope study of the massive sulfide deposit of Filon Norte, Tharsis Mine, Spain

    NASA Astrophysics Data System (ADS)

    Kase, K.; Yamamoto, M.; Nakamura, T.; Mitsuno, C.

    1990-10-01

    The volcanogenic massive sulfide deposit of Filon Norte at Tharsis is hosted by carbonaceous black slate and connected only partly with stockwork veins. The massive ores are usually composed of fine-grained pyrite with subordinate amounts of sphalerite, chalcopyrite, galena and arsenopyrite. Monoclinic pyrrhotite sometimes occurs in massive pyritic ores in the apparently middle and upper horizons of the orebody, and siderite-rich ores are interstratified with compact pyritic ores in the apparently lower horizons. From the occurrence of monoclinic pyrrhotite, together with the FeS contents of sphalerite mostly ranging from 11 to 16 mol %, it is inferred that the sulfide minerals of the massive orebody were precipitated in euxinic muds on the sea-floor at temperatures below 250°C. The negatively shifted, highly variable δ 34S values of the massive ores and their close similarity to those of the underlying black slates strongly suggest that the sulfide sulfur of the massive orebody and the slates is cognate and biogenic.

  10. Cesium and strontium tolerant Arthrobacter sp. strain KMSZP6 isolated from a pristine uranium ore deposit.

    PubMed

    Swer, Pynskhem Bok; Joshi, Santa Ram; Acharya, Celin

    2016-12-01

    Arthrobacter sp. KMSZP6 isolated from a pristine uranium ore deposit at Domiasiat located in North-East India exhibited noteworthy tolerance for cesium (Cs) and strontium (Sr). The strain displayed a high minimum inhibitory concentration (MIC) of 400 mM for CsCl and for SrCl2. Flow cytometric analysis employing membrane integrity indicators like propidium iodide (PI) and thiazole orange (TO) indicated a greater sensitivity of Arthrobacter cells to cesium than to strontium. On being challenged with 75 mM of Cs, the cells sequestered 9612 mg Cs g(-1) dry weight of cells in 12 h. On being challenged with 75 mM of Sr, the cells sequestered 9989 mg Sr g(-1) dry weight of cells in 18 h. Heat killed cells exhibited limited Cs and Sr binding as compared to live cells highlighting the importance of cell viability for optimal binding. The association of the metals with Arthrobacter sp. KMSZP6 was further substantiated by Field Emission-Scanning Electron Microscopy (FE-SEM) coupled with Energy dispersive X-ray (EDX) spectroscopy. This organism tolerated up to 1 kGy (60)Co-gamma rays without loss of survival. The present report highlights the superior tolerance and binding capacity of the KMSZP6 strain for cesium and strontium over other earlier reported strains and reveals its potential for bioremediation of nuclear waste. PMID:27620733

  11. Occurrences and distributions of branched alkylbenzenes in the Dongsheng sedimentary uranium ore deposits, China

    NASA Astrophysics Data System (ADS)

    Tuo, Jincai; Chen, Ru; Zhang, Mingfeng; Wang, Xianbin

    2010-11-01

    A series of branched alkylbenzene ranging from C 15 to C 19 with several isomers (2-5) at each carbon number were identified in sediments from the Dongsheng sedimentary uranium ore deposits, Ordos Basin, China. The distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts. The branched alkylbenzenes from organic-rich argillites and coals range from C 15 to C 19 homologues, in which the C 17 or C 18 dominated. On the other hand, the C 19 branched alkylbenzenes dominated in the sandstone/siltstone extracts. The obvious differences of the branched alkylbenzene distributions between the uranium-host sandstones/siltstones and the interbedded barren organic-rich mudstones/coals probably indicate their potential use as biological markers associated with particular depositional environments and/or maturity diagenetic processes. Possible origins for these branched alkylbenzenes include interaction of simple aromatic compounds with, or cyclization and aromatization reactions of, these linear lipid precursors such as fatty acids, methyl alkanoates, wax esters or alkanes/alkenes that occur naturally in carbonaceous sediments. The possible simple aromatic compounds may include substituted benzenes, functionalized compounds such as phenols that are bound to kerogen at the benzyl position, and phenols that are decomposition products derived from aquatic and terrestrial sources. The distributions of methyl alkanoates and n-alkanes were found to be different between organic-rich mudstone/coal and sandstone/siltstone. From this result, it can be concluded that such differences of the alkylbenzene distributions were mainly resulting from the differences of organic precursors, although maturity effect and radiolytic alteration cannot be completely excluded.

  12. Geochemistry and S, Pb isotope of the Yangla copper deposit, western Yunnan, China: Implication for ore genesis

    NASA Astrophysics Data System (ADS)

    Yang, Xi-An; Liu, Jia-Jun; Cao, Ye; Han, Si-Yu; Gao, Bing-yu; Wang, Huan; Liu, Yue-Dong

    2012-07-01

    The Yangla copper deposit, situated in the middle section of Jinshajiang tectonic belt between Zhongza-Zhongdian block and Changdu-Simao block, is a representative and giant copper deposit that has been discovered in Jinshajiang-Lancangjiang-Nujiang region in recent years. There are coupled relationships between Yangla granodiorite and copper mineralization in the Yangla copper deposit. Five molybdenite samples yielded a well-constrained 187Re-187Os isochron age of 233.3 ± 3 Ma, the metallogenesis is therefore slightly younger than the crystallization age of the granodiorite. S, Pb isotopic compositions of the Yangla copper deposit indicate that the ore-forming materials were derived from the mixture of upper crust and mantle, also with the magmatic contributions. In the late Early Permian, the Jinshajiang Oceanic plate was subducted to the west, resulting in the formation of a series of gently dipping thrust faults in the Jinshajiang tectonic belt, meanwhile, accompanied magmatic activities. In the early Late Triassic, which was a time of transition from collision-related compression to extension in the Jinshajiang tectonic belt, the thrust faults were tensional; it would have been a favorable environment for forming ore fluids. The ascending magma provided a channel for the ore-forming fluid from the mantle wedge. After the magma arrived at the base of the early-stage Yangla granodiorite, the platy granodiorite at the base of the body would have shielded the late-stage magma from the fluid. The magma would have cooled slowly, and some of the ore-forming fluid in the magma would have entered the gently dipping thrust faults near the Yangla granodiorite, resulting in mineralization.

  13. Monzonitoid magmatism of the Glukhoe gold ore deposit (Primorye): U-Pb, SHRIMP dating, petrochemical and minor-element compositions, and peculiar features of noble metal mineralization

    NASA Astrophysics Data System (ADS)

    Sakhno, V. G.; Kovalenko, S. V.; Barinov, N. N.; Lyzganov, A. V.; Kuznetsov, Yu. A.

    2015-11-01

    Monzogabbrodiorites and monzodiorites from the Tatibin Group of Central Sikhote Alin (Primorye), which hosts the Glukhoe gold ore deposit, are considered with discussion of the most important data on the geological structure and composition of magmatic complexes and the results of U-Pb and SHRIMP dating. It is first established that mineral associations of the gold ore deposit include native Pt, Cu, and other compounds and mineral associations. Their formation conditions of both scientific and practical significance are analyzed.

  14. Formation of a magmatic-hydrothermal ore deposit: insights with LA-ICP-MS analysis of fluid inclusions

    PubMed

    Audetat; Gunther; Heinrich

    1998-03-27

    The physical and chemical mechanism of ore precipitation in the Yankee Lode tin deposit (Mole Granite, Australia) was quantified by direct trace-element microanalysis of fluid inclusions. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure element concentrations in a series of fluid inclusions representing the fluid before, during, and after the deposition of cassiterite (SnO2). Tin precipitation was driven by mixing of hot magmatic brine with cooler meteoric water. At the same time, a separate magmatic vapor phase selectively transported copper and boron into the liquid mixture.

  15. Formation of a magmatic-hydrothermal ore deposit: insights with LA-ICP-MS analysis of fluid inclusions

    PubMed

    Audetat; Gunther; Heinrich

    1998-03-27

    The physical and chemical mechanism of ore precipitation in the Yankee Lode tin deposit (Mole Granite, Australia) was quantified by direct trace-element microanalysis of fluid inclusions. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure element concentrations in a series of fluid inclusions representing the fluid before, during, and after the deposition of cassiterite (SnO2). Tin precipitation was driven by mixing of hot magmatic brine with cooler meteoric water. At the same time, a separate magmatic vapor phase selectively transported copper and boron into the liquid mixture. PMID:9516106

  16. Ore formation in porphyry-type deposits during incrementally built magma chamber and fluid sparging

    NASA Astrophysics Data System (ADS)

    Vigneresse, J. L.; Bachmann, O.; Huber, C.; Parmigiani, A.; Dufek, J.; Campos, E.

    2012-04-01

    Porphyry-type mineralizations are commonly associated with an underlying magma chamber from which a volatile phase exsolves from the crystallizing magma. We suggest a model of fluid sparging during multiple successive intrusions yielding metals concentration within the gas phase. Metals enrichment by 3-4 orders of magnitude takes place during the magmatic stage prior to hydrothermal effects, resulting from a competition between diffusion and advection of the volatile phase. The model explains why a single intrusion is not efficient enough to lead to economically viable ore deposit, though it also involves a gas phase percolating within a crystalline mush. During multiple intrusions, metals segregate from the new melt to the gas phase by diffusion, as long as the gas has not overcome a critical saturation level (about 20 % gas). Adding gas exsolved, about 4 % at each new magma recharge, overcomes this level. Then, the diffusion process switches toward advection, since the bubbles get interconnected, enhancing the transport of a gas phase enriched in metals. Once advected, the enriched gas phase turns into hydrothermal circulation during which metals condensate. Two non-dimensional numbers, Péclet and Stefan numbers, respectively rule diffusion and advection of elements while heat is lost through cooling. The model also examines the total duration of the process that re-establishes after 4-6 recharges in magma. It also provides an explanation why intrusions are barren or enriched, although they result from similar conditions of magma genesis. Development of a zoned alteration pattern may serve as a guide for prospection.

  17. Enumeration and characterization of microorganisms associated with the uranium ore deposit at Cigar Lake, Canada; Informal report

    SciTech Connect

    Francis, A.J.; Joshi-Tope, G.; Gillow, J.B.; Dodge, C.J.

    1994-03-01

    The high-grade uranium deposit at Cigar Lake, Canada, is being investigated as a natural analog for the disposal of nuclear fuel waste. Geochemical aspects of the site have been studied in detail, but the microbial ecology has not been fully investigated. Microbial populations in an ore sample and in groundwater samples from the vicinity of the ore zone were examined to determine their effect on uranium mobility. Counts of the total number of bacteria and of respiring bacteria were obtained by direct microscopy, and the viable aerobic and anaerobic bacteria were assessed as colony forming units (CFUs) by the dilution plating technique. In addition, the population distribution of denitrifiers, fermenters, iron- and sulfur-oxidizers, iron- and sulfate-reducers, and methanogens was determined by the most probable number (MPN) technique.

  18. Ore mineralogy of the Serra Pelada Au-Pd-Pt deposit, Carajás, Brazil and implications for ore-forming processes

    NASA Astrophysics Data System (ADS)

    Berni, Gabriel V.; Heinrich, Christoph A.; Lobato, Lydia M.; Wall, Vic

    2016-08-01

    Serra Pelada is a world-class hydrothermal Au-Pd-Pt deposit located at the eastern border of the Amazon craton, northern Brazil. The rocks at Serra Pelada have experienced intense tropical weathering for about 70 Ma, but drill core samples preserve the primary mineralogy and hydrothermal alteration features, with extreme grades of Au, Pd and Pt individually reaching hundreds of parts per million (ppm) by weight. Mineralization at Serra Pelada occurs in hydrothermally altered metasiltstones and dolomitic metasandstones at the hinge zone of a recumbent syncline, comprising zones of hematite, chlorite-carbon, argillic, and siliceous alteration. The main hydrothermal gangue minerals are quartz, kaolinite, sericite, amesite, hematite, monazite, florencite and variable amounts of highly reflective carbonaceous matter. Hydrothermal carbon input is evident from precipitated carbon occurring along crenulation planes and veinlets associated with the precious metals. Ore and accessory minerals include a variety of sulphide, selenide, arsenide, sulphate and oxide minerals, including gold with variable metal contents, palladian gold, fischesserite, sudovikovite, sperrylite, selenian braggite, isomertieite, mertieite-II and secondary Au-Pt-Pd alloys. The composition of fischesserite varies from the ideal formula (Ag3AuSe2) towards a more Ag-rich composition, indicating a disordered solid solution form that is stable only above 260 °C, consistent with the high thermal maturity of associated carbonaceous matter approaching graphite. Primary ore and gangue minerals at Serra Pelada comprise a suite of elements that are best transported in oxidising conditions and precipitated upon reduction. This suggests that fluid mixing between a highly oxidised (metal carrier) and a reduced fluid was a key process for high-grade noble metal precipitation at Serra Pelada.

  19. Hydrothermal alteration and the chemistry of ore-forming fluids in an unconformity-type uranium deposit

    SciTech Connect

    Komninou, A.; Sverjensky, D.A.

    1995-07-01

    Compositions of hydrothermal chlorite and fine-grained white mica from the inner and outer alteration halos in the Koongarra U deposit were analyzed by electron microprobe and analytical electron microscopy. Analyses show that although chlorite and white mica compositions vary considerably outside the main ore zone, they are uniform inside the ore zone. Ore-zone chlorite has a ratio of Fe/(Fe + Mg) of 0.25 and low octahedral occupancy (average 5.5 per formula unit), which may represent a mixture of di- and trioctahedral chlorite. White mica has a typical K + Na atomic content of 0.85 per formula unit. These compositions were used to calculate the activity ratios a{sub Fe{sup +2}}/a{sub H{sup +}}{sup 2}, a{sub Mg{sup +2}}/a{sub H{sup +}}{sup 2}, a{sub K{sup +}}/a{sub H{sup +}}, and a{sub Na{sup +}}/a{sub H{sup +}} for the hydrothermal fluids associated with deposition of uraninite. Hydrothermal apatite analyses in conjunction with salinities suggested from fluid inclusion studies were used to calculate the pH of the fluids during the pre-ore alteration. The calculated pH values range from 4.8 to 6.0. Finally, the coexistence of chlorite with quartz and hematite was used to calculate oxygen fugacities. The calculated values are about 2 log units higher than for the hematite-magnetite buffer at 200{degrees}C. Consequently, the oxidation state of the fluid lay in the hematite field and U was probably transported as uranyl complexes.

  20. Metallogeny of the northeastern Pacific Rim: an example of the distribution of ore deposits along a growing continental margin

    USGS Publications Warehouse

    Goldfarb, R.J.; Hart, C.J.; Mortensen, J.K.; Weber, Graeme

    1999-01-01

    The distribution of mineral deposits within northwestern North America (Alaska, Yukon, and northern British Columbia) allows for an in-depth examination of the metallogenic patterns of a growing continental margin. A more complete understanding of the tectonic evolution of this part of the Pacific Rim, achieved over the last 15 to 20 years, now allows for the placement of ore systems into a well-defined plate tectonic framework. Ore deposits older than about 185 Ma represent hydrothermal systems that were active in the platform/shelf environment of ancestral North America's miogeocline or hydrothermal systems developed in oceanic arcs and continental fragments more distal to the craton. These include important SEDEX, VMS, and pre-accretionary porphyry deposits. In contrast, most mineral deposits younger than about 185 Ma were formed within the growing Cordilleran orogen, as terranes were accreted to the continental margin during interactions between the North America and Pacific/Farallon/Kula plates. Such syn- to post-accretionary mineralised systems include many large lode gold and porphyry/skarn systems.

  1. Mineralogy and chemical composition of VMS deposits of northern Apennine ophiolites, Italy: evidence for the influence of country rock type on ore composition

    NASA Astrophysics Data System (ADS)

    Zaccarini, F.; Garuti, G.

    2008-09-01

    In the ophiolites of the Italian northern Apennines, mantle rocks were exposed on the seafloor and eroded prior to the extrusion of pillow basalt and the deposition of pelagic sediments. Various types of VMS deposits occur at different stratigraphic positions in the ophiolite sequence. Stockwork-vein and seafloor-stratiform ore bodies are associated with serpentinized mantle peridotite and serpentinite breccia. A second group of sulfide deposits consist of crosscutting stockwork or conformable stratabound ore bodies emplaced into the pillow basalt, and seafloor-stratiform deposits located at the top of the volcanic pile, in contact with the sedimentary cover. Geochemical and mineralogical differences are observed in the ore and gangue assemblages of the deposits that were formed before the outflow of pillow basalt, and those precipitated during and after basalt extrusion. Compared with basalt-hosted sulfide deposits, the ores associated with serpentinite have a higher Cu/Zn ratio due to a low modal proportion of sphalerite and are enriched in the compatible elements Ni, Cr, and Mg. The Co and Ni of the ores reflect those of pyrite. The Co/Ni ratios of pyrite range from 0.29 to 1.79 (av. = 0.74) in serpentinite-hosted deposits and from 1.09 to 8.0 (av. = 2.59) in basalt-hosted deposits. The composition of chlorite varies from Cr-rich, Mg-clinochlore, in serpentinite-hosted deposits, to Fe-clinochlore with relatively high Mn contents, in basalt-hosted deposits. The sulfides in serpentinite contain accessory chromite that is compositionally similar to chromian spinels from abyssal peridotites. The observed geochemical variations among the various ore types are due to the interaction of the ore-forming fluids with different types of country rock (ultramafic vs. mafic), which involves hydrothermal leaching of metals from the substrate, rock-fluid reactions at the site of ore deposition and the mechanical transfer of detrital material from the country rock to the ore

  2. Boron isotope evidence for the involvement of non-marine evaporites in the origin of the Broken Hill ore deposits

    USGS Publications Warehouse

    Slack, J.F.; Palmer, M.R.; Stevens, B.P.J.

    1989-01-01

    IDENTIFYING the palaeogeographic setting and mode of origin of stratabound ore deposits can be difficult in high-grade metamorphic terranes, where the effects of metamorphism may obscure the nature of the protoliths. Here we report boron isotope data for tourmalines from the early Proterozoic Broken Hill block, in Australia, which hosts giant lead-zinc-silver sulphide deposits. With one exception the 11B/10B ratios are lower than those for all other tourmalines from massive sulphide deposits and tour-malinites elsewhere in the world. We propose that these low ratios reflect leaching of boron from non-marine evaporitic borates by convecting hydrothermal fluids associated with early Proterozoic continental rifting. A possible modern analogue is the Salton Sea geothermal field in California. ?? 1989 Nature Publishing Group.

  3. Geology and ore deposits of the Mahd Adh Dhahab District, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Luce, Robert W.; Bagdady, Abdulaziz; Roberts, Ralph Jackson

    1976-01-01

    The principal ore minerals are pyrite, chalcopyrite, sphalerite, galena, and minor tetrahedrite, argentite, and native gold and silver. The gold and silver occurs finely disseminated in the veins and in the altered selvages of the veins. Widespread potassic and propylitic alteration accompanied the ore-forming processes. Potassium feldspar was introduced during an early stage of vein formation. Isotopic analyses of lead in vein potassium feldspar and galena yield a model age of about 900-1050 million years with the possibility of the original lead source having been remobilized about 600 million years ago. Chlorite and carbonate are also prominent vein minerals.

  4. Mineralogical study of sediment-hosted gold deposits in the Yangshan ore field, Western Qinling Orogen, Central China

    NASA Astrophysics Data System (ADS)

    Liang, Jinlong; Sun, Weidong; Zhu, Sanyuan; Li, He; Liu, Yulong; Zhai, Wei

    2014-05-01

    The Yangshan gold ore field is located in the southern subzone of the Western Qinling Orogen. Mineralization is confined by the east-west-striking Anchanghe thrust fault zone. These subparallel faults constitute a branch of the regional Mianlue structural zone, crosscutting Middle Devonian carbonaceous carbonate and clastic rock sequences, an ore-bearing unit locally named the Sanhekou Formation. The metasedimentary clastic and carbonate rocks containing fine-grained sulfides are the main host rocks of the deposit, with minor mineralization occurring as coarse-grained pyrite-quartz veinlets in black shale and as dissemination in some plagiogranite dykes. Electron microprobe (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses show that arsenian pyrite and arsenopyrite are the major hosts for gold with tens of ppm up to weight percent levels of Au, and the Au contents in arsenopyrite are one order of magnitude higher than those in pyrite. A negative correlation of As and S in arsenian pyrite is consistent with the substitution of As for S in the mineral. Both arsenian pyrite and arsenopyrite in the Yangshan ore field show chemical zonations with middle parts (mantle) enriched in As and Au relative to cores and the outermost rims, reflecting the chemical evolution of ore-forming fluids. High resolution transmission electron microscopy (HRTEM) analysis failed to identify any nanoparticle of native gold even in the highest Au parts of arsenopyrite. This observation combined with the relatively homogenous distribution of Au, a positive correlation of As and Au, and Au/As ratios below the solubility limit of gold in arsenian pyrite and arsenopyrite, suggests that invisible gold is likely present as structurally bound Au+1 in sulfides, although our work cannot exclude the existence of Au nanoparticles in arsenian pyrite as identified in American Carlin-type gold deposits. Submicron native gold may be much more easily found in

  5. The origin of terrestrial pisoliths and pisolitic iron ore deposits: Raindrops and sheetwash in a semi-arid environment

    NASA Astrophysics Data System (ADS)

    Lascelles, Desmond F.

    2016-07-01

    Ooliths evidently form by chemical precipitation in limnic, paralic, fluvial and marine environments, pisoliths, however, appear to be restricted to terrestrial environments. Typically composed of iron, aluminium and manganese sesquioxides with minor admixtures of quartz and kaolinite, they are widely distributed in tropical to subtropical regions overlying deeply weathered soil profiles. Although iron-, aluminium- and manganese-rich end members are important sources of these metals, their genesis is still enigmatic; their formation has never been observed or produced experimentally and current models for their origin are little more than guesses. A new model is presented based on a unique personal observation in which pisoliths are formed by the action of charged raindrops during thunderstorms impacting on dry deeply weathered powdery soils. The pisoliths are transported across pediments by sheetwash, accumulating as thick deposits in the valley floors. Pisolites are characteristically unfossiliferous and typically clearly pedogenic. The absence of fine depositional layering, fossil seeds, leaves and pollen in pisolites is explained by bioturbation and the action of soil organisms during extended pedogenesis while the major coarse bedding features derive from erosional and depositional events in the evolution of the pediment. Pisolitic iron ores (aka channel iron deposits, CID) are a special case of transported pisolitic ferricrust that form an important resource of medium grade iron ore (57-60 wt% Fe) in the Pilbara Region of Western Australia. Apart from minor deposits in the northern Yilgarn Province of Western Australia, they have not been found elsewhere. They differ from normal transported ferricrust and terrestrial pisolites not only in the exceptionally high iron and low alumina and silica content but also in containing abundant fossilised wood particles.

  6. Studies of disseminated gold deposits near Carlin, Nevada: Evidence for a deep geologic setting of ore formation

    SciTech Connect

    Kuehn, C.A.

    1989-01-01

    The Carlin gold deposit occurs in the upper 175 meters of the Siluro-Devonian Roberts Mountains Formation in Eureka County, Nevada. Pre-, syn- and post-gold episodes are distinguished by (1) hydrocarbon maturation, (2) gold mineralization and alteration and (3) subsequent oxidation. Mineralization post-dates Early Cretaceous dikes which cut zones of thermally mature petroleum residue. Preore P-T conditions of 155 {+-} 20 C and 0.6 to 1.4 kb are defined by coexisting saline aqueous and methane-rich fluid inclusions. Main Gold Ore Stage (MGOS) alteration of pyrite-bearing unaltered calcareous carbonaceous argillaceous siltstones progresses from K-feldspar silt and calcite destruction, then dolomite dissolution, and finally illite conversion to dickite/kaolinite in intensely altered silicified zones near hydrothermal conduits. MGOS fluids are acid from elevated CO{sub 2} contents (5-10 mole percent), and also contain appreciable H{sub 2}S, 3 {+-} 1 wt% NaCl and {delta}{sup 18}O{sub H2O} values +5{per thousand} to {gt} +9{per thousand}. CO{sub 2}-exsolution occurs at 215 {+-} 30{degree}C and 800 {+-} 400 bars during portions of MGOS time and constrains ore formation to minimum depths of 4.4 {+-} 2.2 km. Late Gold Ore Stage (LGOS) fluids are non-boiling and gas-poor with {lt}1.5 wt% NaCl and {delta}{sup 18}O{sub H2O} values {le}-4{per thousand} to -3{per thousand}. As LGOS fluids flood the system, calcite {delta}{sup 18}O values shift from near whole-rocks at +12 {+-} 3{per thousand} to 0 {+-} 1{per thousand} in veinlets containing unoxidized As {+-} Sb-phases. Gas-rich MGOS fluids may result from buried intrusions, contact aueroles, or deeper low-grade metamorphism. Deposition may occur in throttling zones where conditions change abruptly from lithostatic to hydrostatic.

  7. Geophysical model of the Cu-Mo porphyry ore deposit at Copper Flat Mine, Hillsboro, Sierra County, New Mexico

    NASA Astrophysics Data System (ADS)

    Gutierrez, Adrian Emmanuel Gutierrez

    A 3D gravity model of the Copper Flat Mine was performed as part of the exploration of new resources in at the mine. The project is located in the Las Animas Mining District in Sierra County, New Mexico. The mine has been producing ore since 1877 and is currently owned by the New Mexico Copper Corporation, which plans o bringing the closed copper mine back into production with innovation and a sustainable approach to mining development. The Project is located on the Eastern side of the Arizona-Sonora-New Mexico porphyry copper Belt of Cretaceous age. Copper Flat is predominantly a Cretaceous age stratovolcano composed mostly of quartz monzonite. The quartz monzonite was intruded by a block of andesite alter which a series of latite dikes creating veining along the topography where the majority of the deposit. The Copper Flat deposit is mineralized along a breccia pipe where the breccia is the result of auto-brecciation due to the pore pressure. There have been a number of geophysical studies conducted at the site. The most recent survey was a gravity profile on the area. The purpose of the new study is the reinterpretation of the IP Survey and emphasizes the practical use of the gravity geophysical method in evaluating the validity of the previous survey results. The primary method used to identify the deposit is gravity in which four Talwani models were created in order to created a 3D model of the ore body. The Talwani models have numerical integration approaches that were used to divide every model into polygons. The profiles were sectioned into polygons; each polygon was assigning a specific density depending on the body being drawn. Three different gridding techniques with three different filtering methods were used producing ten maps prior to the modeling, these maps were created to establish the best map to fit the models. The calculation of the polygons used an exact formula instead of the numerical integration of the profile made with a Talwani approach. A

  8. Lacustrine-humate model for primary uranium ore deposits, Grants uranium region, New Mexico.

    USGS Publications Warehouse

    Turner-Peterson, C. E.

    1985-01-01

    It is concluded that the primary ore formation in the Morrison formation of the San Juan basin, formed during late Jurassic and early Cretaceous, was related to humic-rich pore fluids. The fluids were derived from lacustrine mud-flat facies of the Brushy basin and 'K' shales. The fluids moved into the Westwater Canyon member and the Jackpile sandstone. -K.A.R.

  9. High-grade iron ore deposits of the Mesabi Range, Minnesota-product of a continental-scale proterozoic ground-water flow system

    USGS Publications Warehouse

    Morey, G.B.

    1999-01-01

    The Mesabi Range along the north edge of the Paleoproterozoic Penokean orogen in northern Minnesota has produced 3.6 billion metric tons of ore since its discovery in 1890. Of that amount, 2.3 billion metric tons were extracted from hematite- or geothite-rich deposits generally referred to as 'high-grade' ores. The high-grade ores formed as the Biwabik Iron-Formation was oxidized, hydrated, and leached by solutions flowing along open faults and fractures. The source of the ore-forming solutions has been debated since it was first proposed that the ores were weathering products formed by descending meteoritic ground-water flowing in late Mesozoic time. Subsequently others believed that the ores were better explained by ascending solutions, possbily hydrothermal solutions of pre-Phanerzoic age. Neither Wolff nor Gruner could reconcile their observations with a reasonable source for the solutions. In this paper, I build on modern mapping of the Mesabi Range and mine-specific geologic observations summarized in the literature to propose a conceptual model in which the high-grade ores formed from ascending solutions that were part of continent-scale topographic or gravity-driven ground-water system. I propose that the ground-water system was active during the later stages of the development of a coupled fold and thrust belt and foreland basin that formed during the Penokean orogen.

  10. Reconstructions of subducted ocean floor along the Andes: a framework for assessing Magmatic and Ore Deposit History

    NASA Astrophysics Data System (ADS)

    Sdrolias, M.; Müller, R.

    2006-05-01

    The South American-Antarctic margin has been characterised by numerous episodes of volcanic arc activity and ore deposit formation throughout much of the Mesozoic and Cenozoic. Although its Cenozoic subduction history is relatively well known, placing the Mesozoic arc-related volcanics and the emplacement of ore bodies in their plate tectonic context remains poorly constrained. We use a merged moving hotspot (Late Cretaceous- present) and palaeomagnetic /fixed hotspot (Early Cretaceous) reference frame, coupled with reconstructed spreading histories of the Pacific, Phoenix and Farallon plates to understand the convergence history of the South American and Antarctic margins. We compute the age-area distribution of oceanic lithosphere through time, including subducting oceanic lithosphere and estimate convergence rates along the margin. Additionally, we map the location and migration of spreading ridges along the margin and relate this to processes on the overriding plate. The South American-Antarctic margin in the late Jurassic-early Cretaceous was dominated by rapid convergence, the subduction of relatively young oceanic lithosphere (< 35 m.y. old) and extensive arc volcanism on the overriding plate. Additionally, our reconstructed position of the Farallon-Phoenix ridge during this period corresponds with the emplacement of several ore bodies in southern South America, similar to formation of Miocene to recent ore deposits in the northern Andes due to aseismic ridge subduction. A change in absolute motion of the Pacific plate after ~120 Ma, led to a significant decrease in the convergence rate and the southward migration of the Farallon-Phoenix ridge and this may have contributed to the cessation of back- arc spreading in the "Rocas Verdes" in southern South America. The speed of subduction increased again along the South American-Antarctic margin at ~105 Ma after another change in tectonic regime. Newly created crust from the Farallon-Phoenix ridge continued to be

  11. Mineralogy and fluid inclusions study of carbonate-hosted Mississippi valley-type Ain Allega Pb-Zn-Sr-Ba ore deposit, Northern Tunisia

    NASA Astrophysics Data System (ADS)

    Abidi, R.; Slim-Shimi, N.; Somarin, A.; Henchiri, M.

    2010-05-01

    The Ain Allega Pb-Zn-Sr-Ba ore deposit is located in the flysch zone on the Eastern edge of the Triassic diapir of Jebel Hamra. It is part of the extrusive Triassic evaporate formation along the Ghardimaou-Cape Serrat faults. The ore body consists of argilic-dolomite breccias surrounded by argilo-gypsum Triassic formation, which forms the hanging wall of the deposit, and rimmed by the Paleocene marls. The ore minerals show a cap-rock type mineralization with different styles particularly impregnation in dolomite, cement of breccias, replacement ore and open space filling in the dissolution cavities and fractures. Ore minerals include sphalerite, galena, marcasite and pyrite. Principal gangue minerals are composed of barite, celestite, calcite, dolomite and quartz. The ore minerals are hosted by the Triassic carbonate rocks which show hydrothermal alteration, dissolution and brecciation. X-ray - crystallographic study of barite-celestite mineral series shows that pure barite and celestite are the abundant species, whereas strontianiferous barite (85-96.5% BaSO 4) and barian-celestite (95% SrSO 4) are minor. Primary and secondary mono-phase (liquid only) fluid inclusions are common in celestite. Microthermometric analyses in two-phases (liquid and vapour) fluid inclusions suggest that gangue and ore minerals were precipitated by a low-temperature (180 °C) saline (16.37 wt.% NaCl equivalent) solution originated possibly from a basinal brine with some input from magmatic or metamorphic fluid. Based on geology, mineralogy, texture and fluid characteristics, the Ain Allega deposit is classified as a carbonate-hosted Mississippi valley-type deposit.

  12. Hydrothermal alteration, ore fluid characteristics, and gold depositional processes along a trondhjemite-komatiite contact at Tarmoola, Western Australia

    USGS Publications Warehouse

    Duuring, P.; Hagemann, S.G.; Cassidy, K.F.; Johnson, C.A.

    2004-01-01

    Tarmoola is a structurally controlled Archean orogenic gold deposit hosted in greenschist facies metamorphosed komatiite and trondhjemite in the Leonora district of the Eastern Goldfields province, Yilgarn craton. High-grade (>1 g/t Au) orebodies are located in komatiite wall rock adjacent to the eastern and northeastern margins of the asymmetrical, north-south-striking, Tarmoola trondhjemite intrusion. Gold-bearing veins post-date trondhjemite emplacement (ca. 2700 Ma), quartz diorite dikes (ca. 2667 Ma), and regional greenschist facies metamorphism. Textures and crosscutting relationships in gold-bearing veins indicate two stages of hydrothermal fluid infiltration associated with a single gold-related hydrothermal event: a volumetrically dominant, but gold-poor, stage I fluid and a gold-rich stage II fluid. Gold-bearing veins contain stage I milky quartz and pyrite that are overprinted by stage II quartz-ankerite-muscovite-chalcopyrite-sphalerite-galena-gold-tellurides ?? albite ?? chlorite ?? fuchsite ?? epidote ?? scheelite. Stage I hydrothermal alteration assemblages are different in trondhjemite and komatiite due to contrasting reactions between a common ore fluid and disparate wall-rock chemistry. Stage II fluid-wall rock interaction was minor compared to stage I and is indicated by the overprinting of stage I mineral assemblages by stage II microveins. Wall-rock alteration proximal to veins in trondhjemite is characterized by replacement of igneous plagioclase, amphibole, biotite, and metamorphic chlorite by hydrothermal quartz, muscovite, ankerite, calcite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold, whereas in proximal alteration in komatiite, metamorphic chlorite and talc are replaced by ankerite, quartz, muscovite, albite, chlorite, fuchsite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold. The stage II fluid was enriched in H2O, CO2, Si, Ca, K, Na, S, Au, Ag, Cu, Pb, W, Bi, As, Mo, Zn, and Te. Based on fluid inclusion

  13. Diversity, metal resistance and uranium sequestration abilities of bacteria from uranium ore deposit in deep earth stratum.

    PubMed

    Islam, Ekramul; Sar, Pinaki

    2016-05-01

    Metal resistance and uranium (U) sequestration abilities of bacteria residing in subsurface U ore was investigated using 122 pure culture strains isolated through enrichment. The cumulative frequencies of isolates resistant to each metal tested were as follows: As(V), 74%; Zn, 58%; Ni, 53%; Cd, 47%; Cr(VI), 41%; Co, 40%; Cu, 20%; and Hg, 4%. 16S rRNA gene analysis revealed that isolated bacteria belonged to 14 genera with abundance of Arthrobacter, Microbacterium, Acinetobacter and Stenotrophomonas. Cobalt did not interfere with the growth of most of the bacterial isolates belonging to different groups while U allowed growth of four different genera of which Stenotrophomonas and Microbacterium showed high U tolerance. Interestingly, tolerance to Ni, Zn, Cu, and Hg was observed only in Microbacterium, Arthrobacter, Paenibacillus¸ and Acinetobacter, respectively. However, Microbacterium was found to be dominant when isolated from other five different metal enrichments including U. Uranium removal study showed that 84% of the test bacteria could remove more than 50mgUg(-1) dry weight from 80 or 160mgL(-1) U within 48h. In general, Microbacterium, Arthrobacter and Acinetobacter could remove a higher amount of U. High resolution transmission electron microscopy (HRTEM) study of U exposed cells revealed that accumulated U sequestered mostly around the cell periphery. The study highlights that indigenous U ore deposit bacteria have the potential to interact with U, and thus could be applied for bioremediation of U contaminated sites or wastes.

  14. Diversity, metal resistance and uranium sequestration abilities of bacteria from uranium ore deposit in deep earth stratum.

    PubMed

    Islam, Ekramul; Sar, Pinaki

    2016-05-01

    Metal resistance and uranium (U) sequestration abilities of bacteria residing in subsurface U ore was investigated using 122 pure culture strains isolated through enrichment. The cumulative frequencies of isolates resistant to each metal tested were as follows: As(V), 74%; Zn, 58%; Ni, 53%; Cd, 47%; Cr(VI), 41%; Co, 40%; Cu, 20%; and Hg, 4%. 16S rRNA gene analysis revealed that isolated bacteria belonged to 14 genera with abundance of Arthrobacter, Microbacterium, Acinetobacter and Stenotrophomonas. Cobalt did not interfere with the growth of most of the bacterial isolates belonging to different groups while U allowed growth of four different genera of which Stenotrophomonas and Microbacterium showed high U tolerance. Interestingly, tolerance to Ni, Zn, Cu, and Hg was observed only in Microbacterium, Arthrobacter, Paenibacillus¸ and Acinetobacter, respectively. However, Microbacterium was found to be dominant when isolated from other five different metal enrichments including U. Uranium removal study showed that 84% of the test bacteria could remove more than 50mgUg(-1) dry weight from 80 or 160mgL(-1) U within 48h. In general, Microbacterium, Arthrobacter and Acinetobacter could remove a higher amount of U. High resolution transmission electron microscopy (HRTEM) study of U exposed cells revealed that accumulated U sequestered mostly around the cell periphery. The study highlights that indigenous U ore deposit bacteria have the potential to interact with U, and thus could be applied for bioremediation of U contaminated sites or wastes. PMID:26796528

  15. Extraction and separation of nickel and cobalt from saprolite laterite ore by microwave-assisted hydrothermal leaching and chemical deposition

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Gao, Jian-ming; Yue, Yi; Peng, Ben; Que, Zai-qing; Guo, Min; Zhang, Mei

    2013-07-01

    Extraction and separation of nickel and cobalt from saprolite laterite ore were studied by using a method of microwave-assisted hydrothermal leaching and chemical deposition. The effects of leaching temperature and time on the extraction efficiencies of Ni2+ and Co2+ were investigated in detail under microwave conditions. It is shown that the extraction efficiencies of Ni2+ and Co2+ from the ore pre-roasted at 300°C for 5 h were 89.19% and 61.89% when the leaching temperature and time were about 70°C and 60 min, respectively. For the separation process of Ni and Co, the separation of main chemical components was performed by adjusting the pH values of sulfuric leaching solutions using a NaOH solution based on the different pH values of precipitation for metal hydroxides. The final separation efficiencies of Ni and Co were 77.29% and 65.87%, respectively. Furthermore, the separation efficiencies of Fe of 95.36% and Mg of 92.2% were also achieved at the same time.

  16. Genesis and Paleo-ecological Interpretation of Swamp Ore Deposits at Sahara Paleo-lakes of East Niger

    NASA Astrophysics Data System (ADS)

    Felix-Henningsen, Peter

    In formerly vegetated flat lake-shore areas of Pleistocene and Holocene paleo-lake depressions in the Sahara of East Niger (Ténéré, Tchigai mountains and in the Erg of Bilma), ancient dune sands are covered by rampart-like or flat beds of individual or networked rhizoconcretions. The massive goethite accumulation, which partly includes an outer fringe of lepidocrocite, impregnated the ancient dune sands. Apart from Fe, P, Ca, and Mg, other heavy metals were also concentrated. The formation and morphological differentiation of these swamp ores were generally bound at vegetated shallow water areas of paleo-lakes in ancient dune fields. Accordingly, the swamp ores of the Ténéré, which has flat to undulating relief, display a large dissemination. In contrast, in the Erg of Bilma the high altitude and steep slopes of ancient dune ridges led to steeper shore areas of the paleo-lakes, at which beds of rhizoconcretions were unable to develop. The oxides were formed by oxidation of Fe2 + -ions from the lake water and concentrated around the roots in the upper root zone of the swamp vegetation. The lack of oxygen in the warm lake water of the shore region, as well as the decomposition of vegetation residues, excluded high redox potentials within the deeper water near the subhydric soil surface. Hence, the formation of rhizoconcretions can only be explained by the specific physiological characteristics of the swamp vegetation, which was able to supply oxygen to the roots through an aerenchyma. The release of surplus oxygen from such roots obviously caused high redox potentials at the root surface and in the neighbouring root environment. As a result precipitation of Fe and Mn oxides occurred, which adsorbed nutrients and heavy metals from the soil solution. The redistribution of the ions from the reduced sediments of the lake basin into the root zone of the shore area resulted from diffusion and mass flow. Paleo-climatically, the swamp ore deposits denote humid periods

  17. Combining in situ isotopic, trace element and textural analyses of quartz from four magmatic-hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Tanner, Dominique; Henley, Richard W.; Mavrogenes, John A.; Holden, Peter

    2013-10-01

    This study couples in situ 16O, 17O and 18O isotope and in situ trace element analyses to investigate and characterize the geochemical and textural complexity of magmatic-hydrothermal quartz crystals. Euhedral quartz crystals contemporaneous with mineralization were obtained from four magmatic-hydrothermal ore deposits: El Indio Au-Ag-Cu deposit; Summitville Au-Ag-Cu deposit; North Parkes Cu-Au deposit and Kingsgate quartz-Mo-Bi-W deposit. The internal features of the crystals were imaged using cathodoluminescence and qualitative electron microprobe maps. Quantitative isotopic data were collected in situ using 157 nm laser ablation inductively coupled plasma mass spectrometry (for 40 trace elements in quartz) and sensitive high-resolution ion microprobe (for 3 isotopes in quartz). Imaging revealed fine oscillatory zoning, sector zoning, complex "macromosaic" textures and hidden xenocrystic cores. In situ oxygen isotope analyses revealed a δ18O range of up to 12.4 ± 0.3 ‰ in a single crystal—the largest isotopic range ever ascribed to oscillatory zonation in quartz. Some of these crystals contain a heavier δ18O signature than expected by existing models. While sector-zoned crystals exhibited strong trace element variations between faces, no evidence for anisotropic isotope fractionation was found. We found: (1) isotopic heterogeneity in hydrothermal quartz crystals is common and precludes provenance analysis (e.g., δD-δ18O) using bulk analytical techniques, (2) the trace element signature of quartz is not an effective pathfinder toward noble metal mineralization and (3) in three of the four samples, both textural and isotopic data indicate non-equilibrium deposition of quartz.

  18. Stratification Studies with Sub Grade Iron Ore from Deposit No. 10 and 11A, Bacheli Complex, Bailadila, Chhattisgarh, India

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, Gottumukkala; Markandeya, Ravvala; Sharma, Satish Kumar

    2016-06-01

    Experiments were carried out with two different sizes of (-30 + 6 and -6 + 1 mm) sub grade iron ore sample from Deposit No. 10 and 11A, Bacheli Complex, Bailadila, India to study the stratification behaviour at optimised parameters in a under bed air pulsed jig at 1, 2, 5, 10, 15 and 20 minutes residence time. This paper deals with the rate at which stratification takes place and determines the optimum stratification time (residence time) for above two size fractions. Average apparent density along with Jig Stratification Index (JSI) of both the size fractions was calculated. It was observed that the stratification rate is high for fines (-6 + 1 mm) and stratification index was higher for lump (-30 + 6 mm) when compared with the other size fraction. The maximum JSI observed was 0.35 for lump (-30 + 6 mm) and 0.30 for fines (-6 + 1 mm).

  19. GIS database model for development of mining information system for the Skarn/Porphyry type ore deposit

    NASA Astrophysics Data System (ADS)

    Roh, T.; Choi, Y.; Park, H.

    2009-12-01

    This study presents a prototype of GIS database model for development of mining information system for the Skarn/Porphyry type ore deposit. Database table was established for the analysis of collected datum from mining activity and geological investigation of mine development. Also structure and property of geological/mining information elements composing each table were defined and specified. For each mine, mine shaft, line and point, independent ID code were assigened. Database is also designed to keep the graphic data of Stereophotogrammetry from mining working face and of geophysical and boring investigation. After combining existing mine map and digital elevation map, sample data was inputed to the database. Finally, database system model that can be used for additional development of mining information system was constructed in this study.

  20. Mineralogy and Geochemistry of the Nižná Boca Sb-Au Hydrothermal Ore Deposit (Western Carpathians, Slovakia)

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexander; Pršek, Jaroslav; Chovan, Martin

    2007-01-01

    Samples from hydrothermal Sb-Au mineralization in the area SE of Nižná Boca village in the N&iAzke Tatry Mountains were investigated using a variety of geochemical and mineralogical methods. Ore minerals typically occur in N-S striking quartz-carbonate veins hosted by an I-type biotite granodiorite to tonalite of Variscan Age (the Ďumbier Type). Paragenetic associations in the deposit are comparable to other mineralizations of the same type in the Ďumbierske Nízke Tatry Mountains. A quartz-arsenopyrite, pyrite stage of mineralization is the oldest with a calculated temperature of formation of about 445°C. It is followed by a quartz-carbonate-stibnite, zinkenite stage and, in turn, a quartz-carbonate-sphalerite-galena, boulangerite-gold stage. The gold typically contains between 9-18 wt.% Ag regardless of mineral association. No evidence for further generations of gold was found although it is possible that some gold was remobilized from the structure of the auriferous arsenopyrite. The Au and Ag content of the bulk ore ranges from 0.53 g.t-1 to 20.2 g.t-1 and from 0.9 g.t-1 to 31.2 g.t-1, respectively. A tetrahedrite-chalcopyrite stage is followed by a barite-hematite stage - the youngest assemblage in the deposit. Fluid inclusions from the first mineralization stage are usually less than 3 μm in size and contain less than 3.6 wt.% CO2; salinity, density and homogenization temperature range from 2.7-16.3 wt.% NaCl(eq), 0.85-1.03 g.cm-1 and 128-280°C, respectively.

  1. Model of heat and mass transfer by fluid during formation of Mo-U deposits in the Strel'tsovka ore field, eastern Transbaikal region: Forced convection of solutions generated by a deep source

    NASA Astrophysics Data System (ADS)

    Malkovsky, V. I.; Pek, A. A.; Aleshin, A. P.; Velichkin, V. I.

    2010-02-01

    The Strel’tsovka and Antei uranium deposits located in the Strel’tsovka caldera are unique in ore resources. According to the considered mathematical model, the uranium source of these deposits was related to the middle-lower crustal silicic magma chambers or had mantle origin. Boundary conditions of the model are based on modern views of physicochemical conditions of hydrothermal process in the Strel’tsovka ore field and factors governing ore deposition therein. Modeling results are consistent with morphology of orebodies and ultimate uranium resources of the deposits and thus confirm indirectly that the physicochemical parameters of the ore-forming system are coherent. The maximal duration of uranium ore deposition is estimated at 500 ka.

  2. The role of the Antofagasta-Calama Lineament in ore deposit deformation in the Andes of northern Chile

    NASA Astrophysics Data System (ADS)

    Palacios, Carlos; Ramírez, Luis E.; Townley, Brian; Solari, Marcelo; Guerra, Nelson

    2007-02-01

    During the Late Jurassic-Early Oligocene interval, widespread hydrothermal copper mineralization events occurred in association with the geological evolution of the southern segment of the central Andes, giving rise to four NS-trending metallogenic belts of eastward-decreasing age: Late Jurassic, Early Cretaceous, Late Paleocene-Early Eocene, and Late Eocene-Early Oligocene. The Antofagasta-Calama Lineament (ACL) consists of an important dextral strike-slip NE-trending fault system. Deformation along the ACL system is evidenced by a right-lateral displacement of the Late Paleocene-Early Eocene metallogenic belts. Furthermore, clockwise rotation of the Early Cretaceous Mantos Blancos copper deposit and the Late Paleocene Lomas Bayas porphyry copper occurred. In the Late Eocene-Early Oligocene metallogenic belt, a sigmoidal deflection and a clockwise rotation is observed in the ACL. The ACL is thought to have controlled the emplacement of Early Oligocene porphyry copper deposits (34-37 Ma; Toki, Genoveva, Quetena, and Opache), whereas it deflected the Late Eocene porphyry copper belt (41-44 Ma; Esperanza, Telégrafo, Centinela, and Polo Sur ore deposits). These observations suggest that right-lateral displacement of the ACL was active during the Early Oligocene. We propose that the described structural features need to be considered in future exploration programs within this extensively gravel-covered region of northern Chile.

  3. Goethite-bearing brine inclusions, petroleum inclusions, and the geochemical conditions of ore deposition at the Jumbo mine, Kansas

    SciTech Connect

    Blasch, S.R.; Coveney, R.M. Jr. )

    1988-05-01

    Petroleum-bearing fluid inclusions occur in sphalerite, calcite, dolomite, and barite at the Jumbo mine, a Mississippi Valley-type deposit in eastern Kansas. In addition to petroleum, Na-Ca-Mg-Fe chloride brines were present during deposition of calcite and sphalerite in which primary inclusions contain {approx gt}23 equivalent wt.% NaCl. Dolomite- and barite-hosted inclusions are more dilute, possibly because of mixing between hydrothermal fluids and groundwater during mineralization. Primary oil inclusions in sphalerite have homogenization temperatures (Th) between 85 and 95{degree}C. Aqueous inclusions have Th values ranging from {approximately}90 to 130{degree}C for sphalerite to below {approximately}50{degree}C for barite. Primary brine inclusions in calcite at the Jumbo mine contain goethite, apparently as a daughter mineral. Goethite has also been tentatively identified in inclusions from the Fletcher mine of Missouri. If goethite is a true daughter phase, it implies the presence of oxidized fluids during mineralization. This suggests that ore deposition resulted from interactions between hydrothermal fluids and dilute groundwater.

  4. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  5. Tertiary meteoric hydrothermal systems and their relation to ore deposition, northwestern United States and southern British Columbia

    NASA Astrophysics Data System (ADS)

    Criss, Robert E.; Fleck, Robert J.; Taylor, Hugh P., Jr.

    1991-07-01

    U-bearing Eocene "porphyry" plutons; and (6) Miocene epithermal deposits, most prominently the Au and Ag bearing veins at Silver City and DeLamar, Idaho, the Hg deposits at the McDermitt caldera, Nevada and Oregon, and at Weiser, Idaho, and Au deposits in the Western Cascade Range and Lake County, Oregon. A close spatial association has been demonstrated between ore deposits and rocks having anomalous δ18O values and low δD values. The most important deposits are associated with relatively small (generally 5-300 km2) zones of low δ18O values, and they are particularly closely linked with zones of very steep 18O/16O gradients in the altered rocks. These associations hold much promise for the use of δ18O and δD contour maps in future exploration efforts.

  6. The source of phosphate in the oxidation zone of ore deposits: Evidence from oxygen isotope compositions of pyromorphite

    NASA Astrophysics Data System (ADS)

    Burmann, Fabian; Keim, Maximilian F.; Oelmann, Yvonne; Teiber, Holger; Marks, Michael A. W.; Markl, Gregor

    2013-12-01

    Pyromorphite (Pb5[PO4]3Cl) is an abundant mineral in oxidized zones of lead-bearing ore deposits and due to its very low solubility product effectively binds Pb during supergene alteration of galena (PbS). The capacity of a soil or near-surface fluid to immobilize dissolved Pb depends critically on the availability of phosphate in this soil or fluid. Potential phosphorus sources in soil include (i) release during biological processes, i.e. leaching from litter/lysis of microbial cells (after intracellular enzyme activity) in soil and hydrolysis from soil organic matter by extracellular enzymes and (ii) inorganic phosphate from the dissolution of apatite in the adjacent basement rocks. Intracellular enzyme activity in plants/microorganisms associated with kinetic fractionation produces an oxygen isotope composition distinctly different from inorganic processes in soil. This study presents the first oxygen isotope data for phosphate (δ18OP) in pyromorphite and a comprehensive data set for apatite from crystalline rocks. We investigated 38 pyromorphites from 26 localities in the Schwarzwald (Southwest Germany) and five samples from localities outside the Schwarzwald in addition to 12 apatite separates from gneissic and granitic host rocks. Pyromorphites had δ18OP values between +10‰ and +19‰, comparable to literature data on δ18OP in the readily available P fraction in soil (resin-extractable P) from which minerals potentially precipitate in soils. δ18OP values below the range of equilibrium isotope fractionation can be attributed either to apatites that formed geochemically (δ18OP of apatites:+6‰ to +9‰) or less likely to biological processes (extracellular enzyme activity). However, for most of our samples isotopic equilibrium with ambient water was indicated, which suggests biological activity. Therefore, we conclude that the majority of pyromorphites in oxidized zones of ore bodies formed from biologically cycled phosphate. This study highlights that

  7. A Long-Lived Porphyry Ore Deposit and Associated Upper Crustal Silicic Magma Body, Bajo de la Alumbrera, Argentina

    NASA Astrophysics Data System (ADS)

    Harris, A. C.; Allen, C. M.; Reiners, P. W.; Dunlap, W. J.; Cooke, D. R.; Campbell, I. H.; White, N. C.

    2004-05-01

    Porphyry Cu deposits form within and adjacent to small porphyritic intrusions that are apophyses to larger silicic magma bodies that reside in the upper parts of the Earth's crusts. Centred on these intrusions are hydrothermal systems of exsolved magmatic fluid with a carapace of convectively circulating meteoric water. We have applied several different dating techniques to assess the longevity of the magmatic-hydrothermal system and to define the cooling history of porphyry intrusions at the Bajo de la Alumbrera porphyry Cu-Au deposit, Argentina. The closure temperatures of these techniques range from 800oC (zircon U-Pb) to ~70oC (apatite (U-Th)/He; Fig. 1). The resulting cooling history indicates that the magmatic-hydrothermal system cooled to ca. 200oC by ~1.5 m.y. after the last porphyry intrusion (i.e., 6.96±0.09 Ma; U-Pb zircon age). Based on (U-Th)/He apatite data (closure temperature ~60-70oC), exposure and cessation of the system occurred before 4 Ma. The longevity of the magmatic-hydrothermal system indicated by these results is inconsistent with accepted mechanisms for porphyry Cu deposit formation. Depending on wallrock permeability, depth and cooling method, a 2 km wide by 3 km high intrusion has been predicted to cool between 0.01 to 0.1 m.y. (marked as the grey interval; Cathles et al., 1997 Economic Geology). We have obtained numerous age determinations younger than the U-Pb zircon age of the last known intrusion at Bajo de la Alumbrera. These imply that simple cooling of the small, mineralized porphyries did not happen. For the magmatic-hydrothermal system to have been sustained for longer than 0.1 m.y., either 1) younger small intrusions have been episodically emplaced below the youngest known intrusions, thus prolonging heat flow, or 2) fluids derived from a deeper and larger parental intrusion have been episodically discharged through the ore deposit long after the porphyry intrusion had lost its available heat. In either case, the longevity of

  8. Constraints on the composition of ore fluids and implications for mineralising events at the Cleo gold deposit, Eastern Goldfields Province, Western Australia

    USGS Publications Warehouse

    Brown, S.M.; Johnson, C.A.; Watling, R.J.; Premo, W.R.

    2003-01-01

    The Cleo gold deposit, 55 km south of Laverton in the Eastern Goldfields Province of Western Australia, is characterised by banded iron-formation (BIF)-hosted ore zones in the gently dipping Sunrise Shear Zone and high-grade vein-hosted ore in the Western Lodes. There is evidence that gold mineralisation in the Western Lodes (which occurred at ca 2655 Ma) post-dates the majority of displacement along the Sunrise Shear Zone, but it remains uncertain if the ore in both structures formed simultaneously or separately. Overall, the Pb, Nd, Sr, C. O and S isotopic compositions of ore-related minerals from both the Western Lodes and ore zones in the Sunrise Shear Zone are similar. Early low-salinity aqueous-carbonic fluids and late high-salinity fluids with similar characteristics are trapped in inclusions in quartz veins from both the Sunrise Shear Zone and the Western Lodes. The early CO2, CO2-H2O, and H2O- dominant inclusions are interpreted as being related to ore formation, and to have formed from a single low-salinity aqueous-carbonic fluid as a result of intermittent fluid immiscibility. Homogenisation temperatures indicate that these inclusions were trapped at approximately 280??C and at approximately 4 km depth, in the deeper epizonal range. Differences between the ore zones are detected in the trace-element composition of gold samples, with gold from the Sunrise Shear Zone enriched in Ni, Pb, Sn, Te and Zn, and depleted In As, Bi, Cd, Cu and Sb, relative to gold from the Western Lodes. Although there are differences in gold composition between the Sunrise Shear Zone and Western Lodes, and hence the metal content of ore fluids may have varied slightly between the different ore zones, no other systematic fluid or solute differences are detected between the ore zones. Given the fact that the ore fluids in each zone have very similar bulk properties, the considerable differences in gold grade, sulfide mineral abundance, and ore textures between the two ore zones

  9. Regularities of spatial association of major endogenous uranium deposits and kimberlitic dykes in the uranium ore regions of the Ukrainian Shield

    NASA Astrophysics Data System (ADS)

    Kalashnyk, Anna

    2015-04-01

    During exploration works we discovered the spatial association and proximity time formation of kimberlite dykes (ages are 1,815 and 1,900 Ga for phlogopite) and major industrial uranium deposits in carbonate-sodium metasomatites (age of the main uranium ore of an albititic formation is 1,85-1,70 Ga according to U-Pb method) in Kirovogradsky, Krivorozhsky and Alekseevsko-Lysogorskiy uranium ore regions of the Ukrainian Shield (UkrSh) [1]. In kimberlites of Kirovogradsky ore region uranium content reaches 18-20 g/t. Carbon dioxide is a major component in the formation of hydrothermal uranium deposits and the formation of the sodium in the process of generating the spectrum of alkaline ultrabasic magmas in the range from picritic to kimberlite and this is the connection between these disparate geochemical processes. For industrial uranium deposits in carbonate-sodium metasomatitics of the Kirovogradsky and Krivorozhsky uranium ore regions are characteristic of uranyl carbonate introduction of uranium, which causes correlation between CO2 content and U in range of "poor - ordinary - rich" uranium ore. In productive areas of uranium-ore fields of the Kirovogradsky ore region for phlogopite-carbonate veinlets of uranium ore albitites deep δ13C values (from -7.9 to -6.9o/oo) are characteristic. Isotope-geochemical investigation of albitites from Novokonstantynovskoe, Dokuchaevskoe, Partyzanskoe uranium deposits allowed obtaining direct evidence of the involvement of mantle material during formation of uranium albitites in Kirovogradsky ore region [2]. Petrological characteristics of kimberlites from uranium ore regions of the UkrSh (presence of nodules of dunite and harzburgite garnet in kimberlites, diamonds of peridotite paragenesis, chemical composition of indicator minerals of kimberlite, in particular Gruzskoy areas pyropes (Cr2O3 = 6,1-7,1%, MgO = 19,33-20,01%, CaO = 4,14-4,38 %, the content of knorringite component of most grains > 50mol%), chromites (Cr2O3 = 45

  10. The Kharapeh orogenic gold deposit: Geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran

    USGS Publications Warehouse

    Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farib; Mohajjel, Mohammad; Marsh, Erin E.

    2011-01-01

    The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m in length and ≤1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H2O–CO2±CH4 fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid δ18O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as

  11. Deep-Sea Magnetics on Active and Fossil Hydrothermal Sites: a Tool to Detect and Characterize Submarine Ore Deposits

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Szitkar, F.; Fouquet, Y.; Choi, Y.

    2011-12-01

    Since the first discoveries of hydrothermal sites at mid-ocean ridges in the 70s, international efforts in the deep seafloor exploration have unravelled a wide variety of hydrothermal sites in terms of geological settings, physical parameters, and biological communities as well. Such efforts, coordinated in the InterRidge program since 1992, are becoming even more important when the increasing need in metals for developing economies makes the exploitation of metal sulfides accumulated at deep-sea hydrothermal sites a realistic target. The usual method to find hydrothermal sites is to detect the associated chemical plumes enriched in manganese, methane, hydrogen, helium 3, in the water column. How efficient it has been proven, such a method is limited to the search for active hydrothermal vents. Active vents, however, are not the best places for mining the seafloor, because (1) they host massive sulfides deposits in the making and may not represent the largest accumulation; (2) they are still very hot and would rapidly damage the mining tools; and, last but not the least, (3) they host fragile and precious ecosystem that could be dramatically affected by mining operations. Methods to find fossil hydrothermal sites (i.e. colder and devoid of specific ecosystems) include systematic rock sampling - a very tedious endeavour - and high resolution, near seafloor geophysical surveys. Existing magnetic surveys on basalt-hosted, peridotite-hosted and sediment-hosted sites revealed different types of signatures, which reflect the magnetizations of the host rock and the ore deposit, among others. Basalt-hosted sites exhibit negative magnetic anomalies, i.e. a deficit of magnetization, due to thermal demagnetization and hydrothermal alteration of the highly magnetic basalt, whereas both peridotite-hosted and sediment-hosted sites show positive anomalies, i.e. an excess of magnetization, clearly associated with the ore deposit. Results from recent cruises Serpentine (R

  12. Timing of the formation of the Changba-Lijiagou Pb-Zn ore deposit, Gansu Province, China: Evidence from Rb-Sr isotopic dating of sulfides

    NASA Astrophysics Data System (ADS)

    Hu, Qiaoqing; Wang, Yitian; Mao, Jingwen; Wei, Ran; Liu, Shengyou; Ye, Dejin; Yuan, Qunhu; Dou, Ping

    2015-05-01

    The giant Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe-Chengxian (abbreviated as "Xicheng") ore cluster in Gansu Province, China. The orebodies in the deposit are mainly hosted in the marble, dolomitic marble, and biotite-calcite-quartz schist of the Middle Devonian Anjiacha Formation. The genesis of the deposit has previously been argued to be of SEDEX type (sedimentary exhalative type) or of epigenetic hydrothermal type. This paper reports results of Rb-Sr isotopic dating on sphalerite and pyrite taken from the main orebody, which yield an isochron age of 222.3 ± 2.2 Ma for eight sphalerite samples, and 222.0 ± 3.0 Ma for the eight sphalerite samples combined with four pyrite samples, indicating that the deposit formed during the Late Triassic. The (87Sr/86Sri) value of the sphalerite is 0.71370 ± 0.00013, and that of the sphalerite and pyrite is 0.71371 ± 0.00014, which are identical within experimental error, suggesting that the ore metals are derived mainly from the continental crust. By integrating the present results with the regional geology, we propose that the Changba-Lijiagou Pb-Zn deposit is a product of regional hydrothermal mineralization processes, forced by tectono-magmatic activities, which took place in the Xicheng ore cluster during Triassic orogenic processes.

  13. Dal'negosrk skarn deposit, Sikhote-Alin: Stages and sources of matter for borosilicate ores

    NASA Astrophysics Data System (ADS)

    Karas', O. A.; Ratkin, V. V.

    2014-04-01

    The danburite orebody at the northeastern wall of the open pit of the Dal'negorsk borosilicate deposit is studied. The comparative mineralogical-, isotopic-, and thermobarogeochemical analyses of danburite from the Levoberezhnyi area and datolite of the late skarn stage from the Tsentral'nyi open pit confirms that danburite is a result of the early borosilicate stage of formation of the deposit. Combined with previously published data, it is concluded that marine sedimentary rocks or Early Cretaceous arkose sandstones from the matrix of the Taukhin accretionary prism could be the source of boron.

  14. Geology and ore deposits of the McDermitt Caldera, Nevada-Oregon

    USGS Publications Warehouse

    Rytuba, James J.

    1976-01-01

    The McDermitt caldera is a Miocene collapse structure along the Nevada-Oregon border. The oval-shaped caldera is bounded by arcuate normal faults on the north and south and by rhyolite ring domes on the west. Precollapse ash-flow tuffs exposed within the south caldera rim consist of three cooling units and are peralkaline in composition. Refractive indexes of nonhydrated glasses from basal vitrophyres of the. units range from 1.493 to 1.503 and are typical of comendites. Post-collapse intracaldera rocks consist of tuffaceous lake sediments, rhyolite flows and domes, and ash-flow tuffs. Within the caldera are the mercury mines of Bretz, Cordero, McDermitt, Opalite, and Ruja and the Moonlight uranium mine. The mercury mines are adjacent to ring fracture faults, and the uranium mine and other uranium occurrences are located within rhyolite ring domes. Fluid inclusions in quartz indicate a deposition temperature of 340?C for the uranium deposit and 200?C for the mercury deposits. The mercury deposits formed at shallow depth by replacement of lakebed sediments and volcanic rocks.

  15. Origin of stratiform sediment-hosted manganese carbonate ore deposits: Examples from Molango, Mexico, and TaoJiang, China

    USGS Publications Warehouse

    Okita, P.M.; Shanks, Wayne C.

    1992-01-01

    Carbonate and sulfide minerals from the Molango, Mexico, and TaoJiang, China, Mn deposits display similar and distinctive ??34S and ??13C patterns in intervals of manganese carbonate mineralization. ??13C-values for Mn-bearing carbonate range from -17.8 to +0.5??? (PDB), with the most negative values occurring in high-grade ore zones that are composed predominantly of rhodochrosite. In contrast, calcite from below, within and above Mn-carbonate zones at Molango has ??13C???0??? (PDB). Markedly negative ??13C data indicate that a large proportion of the carbon in Mn-carbonates was derived from organic matter oxidation. Diagenetic reactions using MnO2 and SO2-4 to oxidize sedimentary organic matter were the principle causes of such 12C enrichment. Pyrite content and sulfide ?? 34S-values also show distinctive variations. In unmineralized rocks, very negative ??34S-values (avg. < -21??? CDT) and abundant pyrite content suggest that pyrite formed from diagenetic, bacteriogenic sulfate reduction. In contrast, Mn-bearing horizons typically contain only trace amounts of pyrite (e.g., <0.5 wt% S with ??34S-values 34S-enriched, in some cases to nearly the value for contemporaneous seawater. 34S-enriched pyrite from the Mn-carbonate intervals indicates sulfide precipitation in an environment that underwent extensive SO2-4 reduction, and was largely a closed system with regard to exchange of sulfate and dissolved sulfide with normal seawater. The occasional occurrence of 34S-depleted pyrite within Mn-carbonate zones dominated by 34S-enriched pyrite is evidence that closed-system conditions were intermittent and limited to local pore waters and did not involve entire sedimentary basins. Mn-carbonate precipitation may have occluded porosity in the surficial sediments, thus establishing an effective barrier to SO2-4 exchange with overlying seawater. Similar isotopic and mineralogic characteristics from both the Molango and TaoJiang deposits, widely separated in geologic time and

  16. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    USGS Publications Warehouse

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad

    2010-01-01

    In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au, or barite. Numerous occurrences of hydrothermal zebra dolomite (HZD), comprised of alternating layers of dark replacement and light void-filling sparry or saddle dolomite, are present in Paleozoic platform and slope carbonate rocks on the eastern side of the Great Basin physiographic province. Locally, it is associated with mineral deposits of barite, Ag-Pb-Zn, and Au. In this paper the spatial distribution of HZD occurrences, their stratigraphic position, morphological characteristics, textures and zoning, and chemical and stable isotopic compositions were determined to improve understanding of their age, origin, and relation to dolostone, ore deposits, and the tectonic evolution of the Great Basin. In northern and central Nevada, HZD is coeval and cogenetic with Late Devonian and Early Mississippian Sedex Au, Zn, and barite deposits and may be related to Late Ordovician Sedex barite deposits. In southern Nevada and southwest California, it is cogenetic with small MVT Ag-Pb-Zn deposits in rocks as young as Early Mississippian. Over Paleozoic time, the Great Basin was at equatorial paleolatitudes with episodes of arid paleoclimates. Several occurrences of HZD are crosscut by Mesozoic or Cenozoic intrusions, and some host younger pluton-related polymetallic replacement and Carlin-type gold deposits. The distribution of HZD in space (carbonate platform, margin, and slope) and stratigraphy (Late Neoproterozoic Ediacaran-Mississippian) roughly parallels that of dolostone and both are prevalent in Devonian strata. Stratabound HZD is best developed in Ediacaran and Cambrian units, whereas

  17. Systematics of hydrothermal alteration at the volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) deposit - implications for ore genesis, structure and exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    NASA Astrophysics Data System (ADS)

    Kampmann, Tobias C.; Jansson, Nils J.; Stephens, Michael B.; Majka, Jarosław

    2016-04-01

    The Palaeoproterozoic, volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit was mined for base and precious metals during several centuries, until its closure in 1992. The deposit is located in a 1.9 Ga ore district in the Bergslagen lithotectonic unit, Fennoscandian Shield, south-central Sweden. Both the ores and their host rock underwent polyphase ductile deformation, and metamorphism under amphibolite facies and later retrograde conditions at 1.9-1.8 Ga (Svecokarelian orogenic system). This study has the following aims: (i) Classify styles and intensities of alteration in the hydrothermally altered zone at Falun; (ii) identify precursor rocks to hydrothermally altered rocks and their spatial distribution at the deposit; (iii) evaluate the chemical changes resulting from hydrothermal alteration using mass change calculations; and (iv) assess the pre-metamorphic alteration assemblages accounting for the observed metamorphic mineral associations in the altered rocks at Falun. Results will have implications for both the ore-genetic and structural understanding of the deposit, as well as for local and regional exploration. Metamorphic mineral associations in the altered rocks include biotite-quartz-cordierite-(anthophyllite) and, more proximally, quartz-anthophyllite-(biotite-cordierite/almandine), biotite-cordierite-(anthophyllite) and biotite-almandine-(anthophyllite). The proximal hydrothermally altered zone corresponds to intense chlorite-style alteration. Subordinate dolomite or calcite marble, as well as calc-silicate (tremolite, diopside) rocks are also present at the deposit. Metavolcanic rocks around the deposit are unaltered, weakly sericitized or sodic-altered. Immobile-element (e.g. Zr, TiO2, Al2O3, REE) systematics of the silicate-rich samples at and around the deposit suggest that the precursors to the hydrothermally altered rocks at Falun were predominantly rhyolitic in composition, dacitic rocks being subordinate and mafic-intermediate rocks

  18. Beyond the obvious limits of ore deposits: The use of mineralogical, geochemical, and biological features for the remote detection of mineralization

    USGS Publications Warehouse

    Kelley, D.L.; Kelley, K.D.; Coker, W.B.; Caughlin, B.; Doherty, M.E.

    2006-01-01

    Far field features of ore deposits include mineralogical, geochemical, or biological attributes that can be recognized beyond the obvious limits of the deposits. They can be primary, if formed in association with mineralization or alteration processes, or secondary, if formed from the interaction of ore deposits with the hydrosphere and biosphere. This paper examines a variety of far field features of different ore deposit types and considers novel applications to exploration and discovery. Primary far field features include mineral and rock chemistry, isotopic or element halos, fluid pathways and thermal anomalies in host-rock sequences. Examples include the use of apatite chemistry to distinguish intrusive rocks permissive for iron oxide copper gold (IOCG) and porphyry deposits; resistate mineral (e.g., rutile, tourmaline) chemistry in exploration for volcanogenic massive sulfide (VMS), orogenic gold, and porphyry deposits; and pyrite chemistry to vector toward sedimentary exhalative (sedex) deposits. Distinctive whole-rock geochemical signatures also can be recognized as a far field feature of porphyry deposits. For example, unique Sr/Y ratios in whole-rock samples, used to distinguish barren versus fertile magmas for Cu mineralization, result from the differentiation of oxidized hydrous melts. Anomalous concentrations of halogen elements (Cl, Br, and I) have been found for distances of up to 200 m away from some mineralized centers. Variations in isotopic composition between ore-bearing and barren intrusions and/or systematic vertical and lateral zonation in sulfur, carbon, or oxygen isotope values have been documented for some deposit types. Owing to the thermal aureole that extends beyond the area of mineralization for some deposits, detection of paleothermal effects through methods such as conodont alteration indices, vitrinite or bitumen reflectance, illite crystallinity, and apatite or zircon thermochronology studies also can be valuable, particularly for

  19. The distribution of trace elements in a range of deep-sea sulphide ore deposits and their impact on seafloor mining

    NASA Astrophysics Data System (ADS)

    Fallon, E. K.; Scott, T. B.; Brooker, R. A.

    2015-12-01

    Acid rock drainage is a natural weathering process that is often exacerbated by mining activities, common in onshore sulphide ore deposits, that can lead to considerable environmental impact. A similar 'weathering process' occurs at seafloor massive sulphide (SMS) ore deposits. In contrast to the onshore situation, the expected consequence in the marine environment is often considered to be oxide formation, negligible metal release and minimal net acid generation due to the high buffering capacity of seawater and low solubility of iron at near neutral pH. However, no dissolution studies exist that emulate the true composition of sulphide ore deposits that either sit passively on the seafloor or are actively mined in this colder, more saline, and alkaline environment. In particular, these deposits will include a variety of minerals, and it is the interaction of these minerals and inclusions in regards to galvanic cells that can subsequently increase the dissolution of metals into the water column. Any heavy metal release that is not balanced by subsequent oxidation and precipitation, has the potential to produce toxicity for benthic ecosystems, bioaccumulation and dispersal through currents. The present work has sought to provide a pilot investigation on the deep sea weathering of sulphide minerals, by identifying the mineral phases, trace elements and potential galvanic couples that may arise in sulphide mineral samples collected from various tectonic settings. Samples have been analysed using EMPA and LA-ICPMS in order to identify the range of trace elements and toxins that may be contributed to the water column, especially heavy metals and environmental toxins (e.g. Fe, Cu, Zn, Pb, Co, Ni, Cd, As, Sb, Sn, Hg). Our observations raise important questions about which ore deposits could have more or less environmental impact during any mining activity. These observations will be used to design oxidative dissolution experiments at deep-sea conditions utilising the

  20. Sulfuric acid karst and its relationship to hydrocarbon reservoir porosity, native sulfur deposits, and the origin of Mississippi Valley-type ore deposits

    SciTech Connect

    Hill, C.A. , Albuquerque, NM )

    1993-03-01

    The Delaware Basin of southeastern New Mexico and West Texas contains hydrocarbons and native sulfur in the basin and sulfuric acid-formed caves and Mississippi Valley-type (MVT) ore deposits around the margins of the basin. Hydrocarbons reacting with sulfate evaporite rock produced hydrogen sulfide gas, which gas oxidized to native sulfur in the basin and which gas also migrated from basin to reef and accumulated there in structural and stratigraphic traps. In the reduced zone of the carbonate reef margin the H[sub 2]S combined with metal-chloride complexes to form MVTs, and in the oxidized zone later in time the H[sub 2]S formed sulfuric acid which dissolved out the famous caves of the region (e.g., Carlsbad Cavern, Lechuguilla Cave). Sulfuric acid karst can be recognized by the discontinuity, large size, and spongework nature of its cave passages, and by the presence of native sulfur, endellite, and large gypsum deposits within these caves. Sulfuric acid oilfield karst refers to cavernous porosity filled with hydrocarbons and can be produced by the mixing of waters of different H[sub 2]S content or by the oxidation of H[sub 2]S to sulfuric acid. Sulfur and carbon-oxygen isotopes have been used to establish and trace the sequence of related hydrocarbon, sulfur, MVT, and karst events in the Delaware Basin.

  1. Mineralogical siting and distribution of gold in quartz veins and sulfide ores of the Ashanti mine and other deposits in the Ashanti belt of Ghana: genetic implications

    NASA Astrophysics Data System (ADS)

    Oberthür, T.; Weiser, T.; Amanor, J. A.; Chryssoulis, S. L.

    1997-01-01

    The Ashanti belt of Ghana constitutes a gold province which has produced a total of about 1500 t of gold historically. Gold mineralization is found in steep, NNE-SSW to NE-SW trending shear zones predominantly transecting metasediments of the Palaeoproterozoic Birimian Supergroup (2.2-2.1 Ga), disseminated in ca. 2.1 Ga granitoids, in paleo-conglomerates of the Tarkwaian Group (< 2135 Ma), and in recent placers. The distribution of gold, its chemistry, paragenesis and mineralogical siting in the mesothermal ores of the major mines in the Ashanti belt, namely Konongo, Ashanti, Bogosu and Prestea mine, are the subject of this study. At the localities studied, gold is present in two main types of ores: 1. Quartz veins with free-milling gold. The gold is relatively silver-rich (true fineness values from 730 to 954) and is accompanied by a distinct suite of Cu, Pb, Sb sulfides. 2. Sulfide ores, consisting of arsenopyrite, pyrite and rarer pyrrhotite and marcasite, with refractory gold. The ores have apparent fineness values larger than 910. Arsenopyrite and locally (at Bogosu) pyrite were identified as the hosts of submicroscopic gold. Mean concentrations of gold in arsenopyrite in various samples from the different mines, obtained by secondary ion mass spectrometry (SIMS), range from 67 to 314 ppm Au. Gold concentration mapping in individual arsenopyrite crystals from the different deposits revealed similar patterns of gold distribution: the grains possess a gold-poor core, and elevated gold contents are present along distinct crystal growth zones towards their rims. The outermost crystal layer is usually gold-poor. The well-preserved distribution patterns also indicate that remobilization of gold from the sulfides played an insignificant role in the ores of the Ashanti belt. Multiple quartz veining and growth zoning of the sulfides are interpreted as manifestations of multiple episodes of fluid infiltration, fluid flow and mineral deposition. The bimodal occurrence of

  2. Origin and evolution of ore-forming fluids in the Hemushan magnetite-apatite deposit, Anhui Province, Eastern China, and their metallogenic significance

    NASA Astrophysics Data System (ADS)

    Luo, Gan; Zhang, Zhiyu; Du, Yangsong; Pang, Zhenshan; Zhang, Yanwen; Jiang, Yongwei

    2015-12-01

    The Middle-Lower Yangtze River Metallogenic Belt in the northern Yangtze Block is one of the most important economic mineral districts in China. The Hemushan deposit is a medium-class Fe deposit located in the southern part of the Ningwu iron ore district of the Middle-Lower Yangtze River Metallogenic Belt. The Fe-orebodies are mainly hosted in the contact zone between diorite and Triassic marble. The actinolite-phlogopite-apatite-magnetite ore shows metasomatic/filling textures and disseminated/mesh-vein structures. Based on evidences and petrographic observations, the ore-forming process can be divided into three distinct periods-the early metallogenic period (albite-diopside stage), the middle metallogenic period (magnetite stage and hematite stage), and the late metallogenic period (quartz-pyrite stage and carbonate stage). Fluid inclusion studies show four types of inclusions: type I daughter mineral-bearing three-phase inclusions (L + V + S), type II vapor-rich two-phase inclusions (L + V), type III liquid-rich two phase inclusions (L + V), and minor type IV liquid-phase inclusions (L). Apatites from the magnetite stage contain type I, type II and type III inclusions; anhydrites from the hematite stage mainly contain abundant type II inclusions and relatively less type I inclusions; quartz and calcite from the late metallogenic stage are mainly characterized by type III inclusions. Laser Raman spectroscopy and microthermometry of fluid inclusions show that the ore-forming fluids broadly correspond to unsaturated NaCl-H2O system. From the magnetite stage to the carbonate stage, the ore-forming fluids evolved from moderate-high temperature (average 414 °C), moderate salinity (average 25.01 wt.% NaCl equiv.) conditions to low temperature (average 168 °C), low salinity (average 6.18 wt.% NaCl equiv.) conditions. Hydrogen and oxygen isotopic studies indicate that the ore-forming fluid during the early stage of middle metallogenic period was mainly of magmatic

  3. Magmatic ore deposits in layered intrusions - Descriptive model for reef-type PGE and contact-type Cu-Ni-PGE deposits

    USGS Publications Warehouse

    Zientek, Michael L.

    2012-01-01

    Layered, ultramafic to mafic intrusions are uncommon in the geologic record, but host magmatic ore deposits containing most of the world's economic concentrations of platinum-group elements (PGE) (figs. 1 and 2). These deposits are mined primarily for their platinum, palladium, and rhodium contents (table 1). Magmatic ore deposits are derived from accumulations of crystals of metallic oxides, or immiscible sulfide, or oxide liquids that formed during the cooling and crystallization of magma, typically with mafic to ultramafic compositions. "PGE reefs" are stratabound PGE-enriched lode mineralization in mafic to ultramafic layered intrusions. The term "reef" is derived from Australian and South African literature for this style of mineralization and used to refer to (1) the rock layer that is mineralized and has distinctive texture or mineralogy (Naldrett, 2004), or (2) the PGE-enriched sulfide mineralization that occurs within the rock layer. For example, Viljoen (1999) broadly defined the Merensky Reef as "a mineralized zone within or closely associated with an unconformity surface in the ultramafic cumulate at the base of the Merensky Cyclic Unit." In this report, we will use the term PGE reef to refer to the PGE-enriched mineralization, not the host rock layer. Within a layered igneous intrusion, reef-type mineralization is laterally persistent along strike, extending for the length of the intrusion, typically tens to hundreds of kilometers. However, the mineralized interval is thin, generally centimeters to meters thick, relative to the stratigraphic thickness of layers in an intrusion that vary from hundreds to thousands of meters. PGE-enriched sulfide mineralization is also found near the contacts or margins of layered mafic to ultramafic intrusions (Iljina and Lee, 2005). This contact-type mineralization consists of disseminated to massive concentrations of iron-copper-nickel-PGE-enriched sulfide mineral concentrations in zones that can be tens to hundreds

  4. Paragenetic and minor- and trace-element studies of Mississippi Valley-type ore deposits of the Silesian-Cracow district, Poland

    USGS Publications Warehouse

    Viets, J.G.; Leach, D.L.; Lichte, F.E.; Hopkins, R.T.; Gent, C.A.; Powell, J.W.

    1996-01-01

    Paragenetic and minor- and trace-element studies were conducted on samples of epigenetic ore and gangue minerals collected from mines and drill core in the Silesian-Cracow (S-C) district of southern Poland. Four discrete mineral suites representing four mineralizing stages can be identified throughout the district. The earliest epigenetic minerals deposited during stage 1 consist of a late dolomite cement together with minor pyrite and marcasite. Stage 2 was the first ore-forming stage and included repetitive deposition of sphalerite and galena in a variety of morphologies. Stage 3 abruptly followed the first ore stage and deposited marcasite and pyrite with variable amounts of late sphalerite and galena. In the samples studied, minerals deposited during stage 3 are predominately marcasite-pyrite with minor sphalerite and galena in the Pomorzany and Olkusz mines, whereas, at the Trzebionka mine, stage 3 mineralization deposited mostly galena and sphalerite with little marcasite or pyrite. Stage 4 minerals include contains barite, followed by calcite, with very minor pyrite and a rare, late granular sphalerite. Compared to other major Mississippi Valley-type (MVT) districts of the world, the Silesian-Cracow district contains sphalerite with the second largest range in Ag concentrations and the largest range in Fe and Cd concentrations of any district. Unlike in other districts, very wide ranges in minor- and trace-element concentrations are also observed in paragenetically equivalent samples collected throughout the district. This wide range indicates that the minor- and trace-element content of the ore-forming environment was highly variable, both spatially and temporally, and suggests that the hydrologic system that the ore fluids traversed from their basinal source was very complex. Throughout the district, a significant increase in Tl, Ge, and As concentrations is accompanied by a lightening of sulfur isotopes between stage 2 and stage 3 minerals. This change

  5. The Reocín zinc-lead deposit, Spain: paleomagnetic dating of a late Tertiary ore body

    USGS Publications Warehouse

    Symons, David T. A.; Lewchuk, Michael T.; Kawasaki, Kazuo; Velasco, Francisco; Leach, David L.

    2009-01-01

    The Reocín mine in northern Spain’s Basque–Cantabrian basin exploited a world-class Mississippi Valley-type Zn–Pb deposit. Its epigenetic mineralization is in Urgonian 116 ± 1 Ma dolomitized limestones of the Santillana syncline, which was formed by Oligocene and mid Miocene pulses of the Pyrenean orogeny. Paleomagnetic results (22 sites, 274 specimens) in mineralization isolated a stable remanence (ChRM) in pyrrhotite and minor magnetite inclusions in ore specimens, Zn concentrate, and tailings. A fold test shows that the ChRM is substantially post-folding. The mineralization’s paleopole lies on the European apparent polar wander path and indicates that the mineralization was formed at 15 ± 10 Ma. We postulate that brines originated in underlying Triassic and Lower Cretaceous sedimentary rocks and were driven upward into the host rocks by the hydraulic gradient created by the nearby Asturian massif.

  6. Syndepositional and postdepositional features of the manganese ore deposits of the Proterozoic Penganga group, Adilabad district, Andhra Pradesh, India

    NASA Astrophysics Data System (ADS)

    Bandopadhyay, P. C.

    1988-04-01

    The Proterozoic Penganga Group consisting of terrigenous and orthochemical sediments including a manganese orebody is well developed in the northwestern part of the Adilabad district, Andhra Pradesh. The manganese orebody of unmetamorphosed and undeformed, interbanded manganese oxide ore, chert, and minor calcareous shale has retained excellent syndepositional and postdepositional features both on the macro-and microscales. The primary depositional features include meso- and microbands of manganese oxide and silica of different descriptions, scour-and-fill structures, and Mn oxide micronodules. Spherical siliceous μm-sized structures and other features of biogenic origin have been observed. Diagenetic features such as fabric changes, syneresis cracks, concretionary pods, and Mn oxide nodules have been recorded. They are accompanied by penecontemporaneous deformation structures such as pinch-and-swell structures, gravity-density features, brecciation, and folding and faulting of various kinds. All these features suggest that the manganese orebody was formed in a shallow-marine environment on a stable shelf possibly behind a barrier bar and subsequently underwent diagenetic reorganization and penecontemporaneous deformation when the sediments were still in a hydroplastic state.

  7. Measurement of uranium series radionuclides in rock and groundwater at the Koongarra ore deposit, Australia, by gamma spectrometry

    SciTech Connect

    Yanase, Nobuyuki; Sekine, Keiichi

    1995-12-31

    Gamma spectrometry without any self-absorption correction was developed to measure low energy gamma rays emitted by uranium and actinium series radionuclides in rock samples and groundwater residues collected at the Koongarra ore deposit, Australia. Thin samples were prepared to minimize the self-absorption by uranium in the samples. The present method gave standard deviations of 0.9 to 18% for the measurements of concentrations of uranium and actinium series radionuclides. The concentrations of {sup 238}U, {sup 230}Th and {sup 235}U measured by gamma spectrometry were compared with those by alpha spectrometry that requires a complicated chemical separation procedure. The results obtained by both methods were in fairly good agreement, and it was found that the gamma spectrometry is applicable to rock and groundwater samples having uranium content sup to 8.1% (10{sup 3} B1/g) and 3 Bq/l of {sup 238}U, respectively. The detection limits were calculated to be of the order of 10{sup {minus}2} Bq/g for rock samples and 10{sup {minus}1} Bq/l for groundwater samples. The concentrations of uranium and actinium series radionuclides can be determined precisely in these samples using gamma spectrometry without any self-absorption correction.

  8. Rock chemistry and fluid inclusion studies as exploration tools for ore deposits in the Sila batholith, southern Italy

    USGS Publications Warehouse

    de Vivo, B.; Ayuso, R.A.; Belkin, H.E.; Lima, A.; Messina, A.; Viscardi, A.

    1991-01-01

    The Sila batholith is the focus of an extensive petrogenetic research program, which includes an assessment of its potential to host granite-related ore deposits. Univariate and multivariate statistical techniques were applied to major- and minor-element rock geochemical data. The analysis indicates that the highest potential for mineralization occurs in corundum-normative, peraluminous, unfoliated, relatively late-stage plutons. The plutons are enriched in Rb, Nb, Ta and U, but depleted in Fe, Mg and Sr. The K/Rb, Ba/Rb, Rb/Sr and Rb3/Ba??Sr??K indices and high R-factor scores of Si-K-Rb are typical of mineralized granitic rocks. A reconnaissance fluid inclusion study indicates that the sub-solidus rock was infiltrated by solutions of widely different temperatures (50-416??C) and variable salinities (0 to ???26 wt.% NaCl equivalent). The higher-temperature solutions probably represent granite or magmatic-related Hercynian fluids, whereas the lower-temperature fluids may be either Hercynian or Alpine in age. Fluids with characteristics typical of mineralized "porphyry" systems have not been recognized. ?? 1991.

  9. Genesis of sediment-hosted disseminated-gold deposits by fluid mixing and sulfidization: chemical-reaction-path modeling of ore- depositional processes documented in the Jerritt Canyon district, Nevada

    USGS Publications Warehouse

    Hofstra, A.H.

    1991-01-01

    Integrated geologic, geochemical, fluid-inclusion, and stable-isotope studies of the gold deposits in the Jerritt Canyon district, Nevada, provide evidence that gold deposition was a consequence of both fluid mixing and sulfidization of host-rock iron. Chemical-reaction-path models of these ore-depositional processes confirm that the combination of fluid mixing, including simultaneous cooling, dilution, and oxidation of the ore fluid, and wall-rock reaction, with sulfidization of reactive iron in the host rock, explains the disseminated nature and small size of the gold and the alteration zonation, mineralogy, and geochemistry observed at Jerritt Canyon and at many other sediment-hosted disseminated gold deposits. -Authors

  10. Alfred E. Bergeat (1866-1924): a distinguished volcanologist and ore deposit researching scientist at the mining academies of Freiberg (Saxony) and Clausthal (Harz mountains) in Germany

    NASA Astrophysics Data System (ADS)

    Pfaffl, Fritz A.

    2010-06-01

    Alfred E. Bergeat, originated from a family, who produced gold-glance in a factory (porcelain painting), studied mineralogy and geology at the University of Munich from 1886 to 1892. Due to the results of his habilitation work on the volcanism of island arcs, especially of the Stromboli volcanic island in the Tyrrhenian Sea, he became a recognized volcanologist and specialist in volcanic petrography. He further became an explorer of syngenetic, epigenetic and deuterogenic ore deposits at the mining academies (Bergakademien) of Freiberg (Saxony) and Clausthal (Harz mountains). He described these ore deposits in a two-volume manual (1904-1906) which was summarized again in 1913. After his early death in 1924, the two manuals “Die Vulkane” (1925) and “Vulkankunde” (1927) were posthumously published by his colleague and friend Karl Sapper (1866-1945).

  11. Host-rock controlled epigenetic, hydrothermal metasomatic origin of the Bayan Obo REEFe-Nb ore deposit, Inner Mongolia, P.R.C.

    USGS Publications Warehouse

    Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Yinchen, R.

    1992-01-01

    Bayan Obo, a complex rare earth element (REE)FeNb ore deposit, located in Inner Mongolia, P.R.C. is the world's largest known REE deposit. The deposit is chiefly in a marble unit (H8), but extends into an overlying unit of black shale, slate and schist unit (H9), both of which are in the upper part of the Middle Proterozoic Bayan Obo Group. Based on sedimentary structures, the presence of detrital quartz and algal fossil remains, and the 16-km long geographic extent, the H8 marble is a sedimentary deposit, and not a carbonatite of magmatic origin, as proposed by some previous investigators. The unit was weakly regionally metamorphosed (most probably the lower part of the green schist facies) into marble and quartzite prior to mineralization. Tectonically, the deposit is located on the northern flank of the Sino-Korean craton. Many hypotheses have been proposed for the origin of the Bayan Obo deposit; the studies reported here support an epigenetic, hydrothermal, metasomatic origin. Such an origin is supported by field and laboratory textural evidence; 232Th/208Pb internal isochron mineral ages of selected monazite and bastnaesite samples; 40Ar/39Ar incremental heating minimum mineral ages of selected alkali amphiboles; chemical compositions of different generations of both REE ore minerals and alkali amphiboles; and evidence of host-rock influence on the various types of Bayan Obo ores. The internal isochron ages of the REE minerals indicate Caledonian ages for various episodes of REE and Fe mineralization. No evidence was found to indicate a genetic relation between the extensive biotite granitic rocks of Hercynian age in the mine region and the Bayan Obo are deposit, as suggested by previous workers. ?? 1992.

  12. Effects of simulated deposition of acid mist and iron ore particulate matter on photosynthesis and the generation of oxidative stress in Schinus terebinthifolius Radii and Sophora tomentosa L.

    PubMed

    Kuki, Kacilda Naomi; Oliva, Marco Antônio; Pereira, Eduardo Gusmão; Costa, Alan Carlos; Cambraia, José

    2008-09-15

    Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions.

  13. Evolution of volcanic rocks and associated ore deposits in the Marysvale volcanic field, Utah

    USGS Publications Warehouse

    Cunningham, Charles G.; Steven, Thomas A.; Rowley, Peter D.; Naeser, Charles W.; Mehnert, Harald H.; Hedge, Carl E.; Ludwig, Kenneth R.

    1994-01-01

    A geological account on the igneous activity and associated mineral deposition in the volcanic field of Marysvale in Utah is presented. Three episodes (34-22 Ma, 22-14 Ma and 9-5 Ma) involved in the volcanic rock eruption and associated mineralization are described. The first episode is believed to have occurred during the time of tectonic convergence when two contrasting suites of rocks, Mount Dutton Formation and Bullion Canyon Volcanics, erupted concurrently. Mineralization during this period was sparse. In the second episode, change from intermediate to bimodal volcanism occurred. During the third episode, basaltic compositions did not change. Although major element constituent had rhyolites similar to that of the second episode, rhyolites had a marked radiogenic isotope characteristic difference.

  14. Berthierine and chamosite hydrothermal: genetic guides in the Peña Colorada magnetite-bearing ore deposit, Mexico

    NASA Astrophysics Data System (ADS)

    Rivas-Sanchez, M. L.; Alva-Valdivia, L. M.; Arenas-Alatorre, J.; Urrutia-Fucugauchi, J.; Ruiz-Sandoval, M.; Ramos-Molina, M. A.

    2006-10-01

    We report the first finding of berthierine and chamosite in Mexico. They occur in the iron-ore deposit of Peña Colorada, Colima. Their genetic characteristics show two different mineralization events associated mainly to the magnetite ore. Berthierine is an Fe-rich and Mg-low 1:1 layer phyllosilicate of hydrothermal sedimentary origin. Its structure is 7 Å, d hkl [10 0] basal spacing and low degree structural ordering. The phyllosilicate has been identified by a lack of 14 Å basal reflection on X-ray diffraction (XRD) patterns. These data were supported by High Resolution Transmision Electron Microscopy (HRTEM) images that show thick packets of berthierine in well defined parallel plates. From the analysis of Fast Fourier Transform (FFT), we found around [1 0 0] reflections of berhierine 7.12 Å and corresponding angles of hexagonal crystalline structure. Berthierine has a microcrystalline structure, dark green color, and high refraction index (1.64 to 1.65). Birefringence is low, near 0.007 to null and it is associated to nanoparticles (<15 nm) and microparticles of magnetite (<25 μm), fine grain siderite, and organic matter. Its texture is intergranular-interstratified with colloform banding. The chamosite Mg-rich is of hydrothermal epigenetic origin affected by low-degree metamorphism. It is an Fe-rich 2:1 layer silicate, with basal space of 14 Å, d hkl [0 0 1]. The chamosite occurs as lamellar in sizes ranging from 50 to 150 μm. It has intense green color and refraction index from 1.64 to 1.65. The birefringence is near 0.008, with biaxial (-) orientation and a 2V small. It is associated mainly to sericite, epidote, clay, feldspar, and magnetite. Chamosite is emplaced in open spaces filling and linings. Mössbauer spectra of berthierine and chamosite are similar. They show the typical spectra of paramagnetic substances, with two well defined unfoldings corresponding to the oxidation state of Fe+2 and Fe+3. Chemical composition of both minerals was

  15. The geology and ore deposits of Upper Mayflower Gulch, Summit County, Colorado

    USGS Publications Warehouse

    Randall, John Alexander

    1958-01-01

    Upper Mayflower Gulch is on the highly glaciated western side of the Tenmile Range near Kokomo in central Colorado. Somewhat less than $500,000 in silver and gold has been produced from the area since the first mining in the 1880' s. In the mapped area high grade regional metamorphism has produced two varieties of gneiss and a granulite. Total thickness of the rocks is about 5,000 feet. Relict bedding is preserved in compositional banding which strikes north to N. 20 ? E. and dips 70 ? to 80 ? southeast. No significant folding was observed. Normal faulting has occurred since the Precambrian; two major sets of faults are recognizable: (1) a set striking N. 70 ? to 85 ? E. and dipping 75?-85 ? NW; and (2) a set striking N. 70?-50 ? W. and dipping 50?-60 ? SW. Tabular bodies of pegmatite and retrogressively metamorphosed schist along many faults indicate Precambrian movement. The Mayflower fault, a 90 to 300 foot wide zone of siltification and shattered rock, strikes about N. 40 ? W. It extends the entire length of the gulch and appears to form the northern terminus for the northeast trending Mosquito Fault. The Mayflower fault shows repeated movement since the Precambrian, totaling about 3,000 feet of apparent dip slip and 640 feet of apparent strike slip. Faulting during the Tertiary includes both additional movement along Precambrian faults and development of shears trending N. to N. 20 ? E. The shears served as channels for the intrusion of two varieties of quartz latite porphyry dikes. Specular hematite and base-metal sulfide mineralization followed intrusion of the porphyry dikes; the minerals were deposited in open fault zones by high temperature solutions in a low pressure environment. The principal metallic minerals in order of deposition are: hematite, pyrite, chalcopyrite, sphalerite, galena, and rarer argentite. The major mines are the Gold Crest, Payrock, Nova Scotia Boy, and Bird's Nest.

  16. Positive feedback between strain localization and fluid flow at the ductile-brittle transition leading to Pb-Zn-Fe-Cu-Ag ore deposits in Lavrion (Greece)

    NASA Astrophysics Data System (ADS)

    Scheffer, Christophe; Tarantola, Alexandre; Vanderhaeghe, Olivier

    2016-04-01

    At the crustal scale, the ductile-brittle transition (DBT) might correspond to a physical barrier that separates a deep reservoir of metamorphic and magmatic fluids from a shallow reservoir of surficial fluids. Rock rheology, and thus the location of the DBT, is mainly governed by lithology, temperature and the presence/absence of fluids. Accordingly, the position of the DBT potentially evolves during orogenic evolution owing to thermal evolution and fluid circulation. In turn rocks are transferred across it during burial and exhumation. These processes induce connections between fluid reservoirs which might play a role on ore deposition. In this contribution, we discuss the impact of lithological heterogeneities on deformation, fluid flow and ore deposition based on the example of the Lavrion low-angle top-to-the-SSW detachment accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula, localized along the western boundary of the Attic-Cycladic Metamorphic Core Complex, is characterized by Pb-Zn-Fe-Cu-Ag ore mineralization mainly concentrated along a lithological contact (marble/schists) below and within a detachment shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO2, Al2O3, organic matter…). Development of the mylonitic fabric in competent impure blue marble is associated with its preferred dolomitization related to focused fluid infiltration. This mylonitic marble is cross-cut by several cataclastic horizons preferentially developed within the more competent impure blue marble and newly-crystallized dolomitic horizon. These cataclasites are invaded by fluorite and calcite gangue minerals showing locally Mn, Pb, Zn, Fe oxides and/or hydroxides, sphalerite, Ag-galena, Ag-sulfur and native Ag. Oxygen and carbon stable isotopes performed on marble sections point out decarbonation with magmatic contribution and

  17. Sulfur-containing particles emitted by concealed sulfide ore deposits: an unknown source of sulfur-containing particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Cao, J. J.; Li, Y. K.; Jiang, T.; Hu, G.

    2015-06-01

    Sources of sulfur dioxide, sulfates, and organic sulfur compounds, such as fossil fuels, volcanic eruptions, and animal feeding operations, have attracted considerable attention. In this study, we collected particles carried by geogas flows ascending through soil, geogas flows above the soil that had passed through the soil, and geogas flows ascending through deep faults of concealed sulfide ore deposits, and analysed them using transmission electron microscopy. Numerous crystalline and amorphous sulfur-containing particles or particle aggregations were found in the ascending geogas flows. In addition to S, the particles contained O, Ca, K, Mg, Fe, Na, Pb, Hg, Cu, Zn, As, Ti, Sr, Ba, Si, etc. Such particles are usually a few to several hundred nanometres in diameter with either regular or irregular morphology. The sulfur-containing particles originated from deep-seated weathering or faulting products of concealed sulfide ore deposits. The particles suspended in the ascending geogas flow migrated through faults from deep-seated sources to the atmosphere. This is a previously unknown source of the atmospheric particles. This paper reports, for the first time, the emission of sulfur-containing particles into the atmosphere from concealed sulfide ore deposits. The climatic and ecological influences of these sulfur-containing particles and particle aggregations should be assessed.

  18. Sulfur-containing particles emitted by concealed sulfide ore deposits: an unknown source of sulfur-containing particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Cao, J.; Li, Y.; Jiang, T.; Hu, G.

    2014-11-01

    Sources of sulfur dioxide, sulfates, and organic sulfur compounds, such as fossil fuels, volcanic eruptions, and animal feeding operations, have attracted considerable attention. In this study, we collected particles carried by geogas flows ascending through soil, geogas flows above the soil that had passed through the soil, and geogas flows ascending through deep faults of concealed sulfide ore deposits and analyzed them using transmission electron microscopy. Numerous crystalline and amorphous sulfur-containing particles or particle aggregations were found in the ascending geogas flows. In addition to S, the particles contained O, Ca, K, Mg, Fe, Na, Pb, Hg, Cu, Zn, As, Ti, Sr, Ba, Si, etc. Such particles are usually a few to several hundred nanometers in diameter with either regular or irregular morphology. The sulfur-containing particles originated from deep-seated weathering or faulting products of concealed sulfide ore deposits. The particles suspended in the ascending geogas flow migrated through faults from deep-seated sources to the atmosphere. This is a previously unknown source of the atmospheric particles. This paper reports, for the first time, the emission of sulfur-containing particles into the atmosphere from concealed sulfide ore deposits. The climatic and ecological influences of these sulfur-containing particles and particle aggregations should to be assessed.

  19. Geochronology, petrogenesis and tectonic settings of pre- and syn-ore granites from the W-Mo deposits (East Kounrad, Zhanet and Akshatau), Central Kazakhstan

    NASA Astrophysics Data System (ADS)

    Li, GuangMing; Cao, MingJian; Qin, KeZhang; Evans, Noreen J.; Hollings, Pete; Seitmuratova, Eleonora Yusupovha

    2016-05-01

    There is significant debate regarding the mineralization ages of the East Kounrad, Zhanet and Akshatau W-Mo deposits of Central Kazakhstan, and the petrogenesis and tectono-magmatic evolution of the granites associated with these deposits. To address these issues, we present molybdenite Re-Os dating, zircon U-Pb dating, whole rock geochemistry as well as Sr-Nd-Pb and zircon O-Hf isotopic analyses on the pre-mineralization and ore-forming granites. U-Pb dating of zircons from pre-mineralization granitic rocks yield Late Carboniferous ages of 320-309 Ma, whereas ore-forming granites have Early Permian ages of 298-285 Ma. Molybdenite Re-Os isotopic data indicate a mineralization age of ~ 296 Ma at East Kounrad, ~ 294 Ma at Akshatau and ~ 285 Ma at Zhanet. The pre-ore and ore-forming granites are high-K calc-alkaline, metaluminous to slightly peraluminous I-type granites. The pre-mineralization granites are relatively unfractionated, whereas the ore-forming granites are highly fractionated. The fractionating mineral phases are probably K-feldspar, apatite, Ti-bearing phases and minor plagioclase. The pre-mineralization and ore-forming rocks are characterized by similar Sr-Nd-Pb-Hf-O isotopic compositions ((87Sr/86Sr)i = 0.70308-0.70501, εNd (t) = - 0.5 to + 2.8, 207Pb/204Pb = 15.60-15.82, zircon εHf (t) = + 1.2 to + 15.6 and δ18O = + 4.6 to + 10.3‰), whole rock TDMC (Nd) (840-1120 Ma) and zircon TDMC (Hf) (320-1240 Ma). The isotopic characteristics are consistent with a hybrid magma source caused by 10-30% assimilation of ancient crust by juvenile lower crust. The geochronology and geochemistry of these granites show that the Late Carboniferous pre-mineralization granitic rocks formed during subduction, whereas the Early Permian ore-forming, highly fractionated granite probably underwent significant fractionation with a restite assemblage of K-feldspar, apatite, Ti-bearing phases and minor plagioclase and developed during collision between the Yili and Kazakhstan

  20. Genesis and formation conditions of deposits in the unique Strel'tsovka Molybdenum-Uranium ore field: New mineralogical, geochemical, and physicochemical evidence

    NASA Astrophysics Data System (ADS)

    Aleshin, A. P.; Velichkin, V. I.; Krylova, T. L.

    2007-10-01

    The ambiguity of genetic interpretations of uranium ore formation at Mo-U deposits of the Strel’tsovka ore field led us to perform additional geochemical, mineralogical, and thermobarogeochemical studies. As a result, it has been established that closely related U and F were progressively gained in the Late Mesozoic volcanic rocks from the older basic volcanics (170 Ma) to the younger silicic igneous rocks (140 Ma). The Early Cretaceous postmagmatic hydrothermal epoch (140-125 Ma) is subdivided into preore, uranium ore, and first and second postore stages. The primary brannerite-pitchblende ore was formed in association with fluorite. At the first postore stage, this assemblage was replaced by a U-Si metagel, which was previously identified as coffinite. The metagel shows a wide compositional variation; its fine structure has been studied. The preore metasomatic alteration and related veined mineralization were formed under the effect of sodium (bicarbonate)-chloride solution at a temperature of 250-200°C. The uranium ore formation began with albitization and hematitization of rocks affected by supercritical fluid at 530-500°C; brannerite and pitchblende precipitated at 350-300°C. The chondrite-normalized REE patterns of pitchblende hosted in trachybasalt, trachydacite, and granite demonstrate a pronounced Sm-Nd discontinuity and a statistically significant tetrad effect of W type. These attributes were not established in REE patterns of rhyolites derived from the upper crustal magma chamber. This circumstance and a chronological gap of 5 Ma between silicic volcanism and ore formation do not allow us to suggest that uranium was derived from this magma chamber. According to the proposed model, the evolved silicic Li-F magma was a source of uranium. U4+, together with REE, was fractionated into the fluid phase as complex fluoride compounds. The uranium mineralization was deposited at a temperature barrier. It is suggested that hydromica alteration and the

  1. Gold and silver in PGE-Cu-Ni and PGE ores of the Noril'sk deposits, Russia

    NASA Astrophysics Data System (ADS)

    Sluzhenikin, Sergey F.; Mokhov, Andrey V.

    2015-04-01

    Gold and silver contents in Noril'sk ore are controlled by the amount of sulphides and bulk Cu grade. Relative concentrations, re-calculated to 100 % sulphide, depend on type of ore: they are higher for disseminated ore than for massive ore and are the highest for low-sulphide platinum ore. Gold occurs mainly as high-fineness Au-Ag alloy in pyrrhotite-rich ore, whereas silver enters chalcopyrite mainly as solid solution. Increase in Cu grade correlates with an increase in the concentration of silver in chalcopyrite. Gold and silver form discrete minerals such as Au-Cu alloys, Au-Ag alloys, tellurides, sulphides, selenides, sulphobismuthides, Ag and Ag-Pd chlorides in Cu-rich ores; they also enter the structures of complex platinum-group minerals. The Au-Ag mineralisation is related to the post-magmatic hydrothermal stage under temperature conditions of 350-50 °C. Silver entered crystallizing chalcopyrite in solid solution in the late-magmatic stage, while all of the gold and the remainder of the silver and some platinum-group elements were transported predominantly as chloride and hydrosulphide complexes in hydrothermal fluids.

  2. REE, trace elements, Sr, Pb, C, and O isotopes in a zoned skarn ore deposit

    SciTech Connect

    Langmuir, C.; LeHuray, A.; Fairbanks, R.; Meinert, L.

    1985-01-01

    The Groundhog skarn in the Central Mining District, New Mexico, is zoned along its >2km length adjacent to a dike swarm which trends NE toward the Santa Rita porphyry Cu deposit. Isotopes and trace elements in whole rocks and mineral separates from skarn and adjacent carbonate allow the study of the source of the metals and the systematics of trace element behavior in a skarn system. (1) /sup 87/Sr//sup 86/Sr ratios are uniform (.7083 +/- 1) in the carbonate host, but they range up to .714 in hydrothermal calcite and pyx from the skarn, values distinct from both Santa Rita (.706) and carbonate. (2) delta/sup 18/O (SMOW) in carbonate ranges from (+6.3 -+ 23) and is correlated positively with delta/sup 13/C (-5.6-+2.4) and negatively with /sup 87/Sr//sup 86/Sr. Several trace elements also correlate with delta/sup 18/O. (3) Pb isotopes in galenas lie on the regression line for southwestern New Mexico Proterozoic crust. PbS from the skarn closest to Santa Rita has isotope ratios identical to PbS from the Santa Rita pit. (4) Most of the REE are not in gar or pyx. REE abundances are <1X chondrites after HC1 leaches, but in unleached samples can be >20X chondrites. All pyx separates have deep negative Ce and very deep Eu anomalies. Sr isotopes show that neither Santa Rita magma nor carbonate is the sole source of Sr. Pb isotopes are consistent with a Santa Rita source. The Ce anomaly suggests a seawater source for the REE. The data show that many of the metals in the skarn are not derived from the Santa Rita porphyry, and suggest that different elements may be derived from different source rocks.

  3. Sulphur isotope geochemistry of the ores and country rocks at the Almadén mercury deposit, Ciudad Real, Spain

    NASA Astrophysics Data System (ADS)

    Saupé, Francis; Arnold, Michel

    1992-10-01

    Seventy-four new S isotope analyses of ore minerals and country rocks are given for the Hg deposit of Almadén. The spread of the cinnabar δ34S is narrow within each of the three orebodies, but the δ34S average values differ sufficiently between them (mean δ34S: San Nicolas = 0.2 ± 1.1 %., San Francisco = 8.1 ± 0.7%., San Pedro = 5.9 ± 1.0%.) to indicate three different mineralization episodes and possibly processes. The unweighted mean for all cinnabar samples is 5.6%. and the S source is considered to be the host-rocks, either the Footwall Shales ( δ34S = 5.5%.) or the spilites ( δ34 S = 5.1 ± 1.3%.). For geometric and chronologic reasons, the former seem the best potential source. However, the high δ34 S values of the San Francisco cinnabar cannot be explained without addition of heavy S from reduction of seawater sulphate. Orderly distributions of the δ34S values are observed in all three orebodies: (1) their increase from the stratigraphic bottom to the top in the San Pedro orebody is explained by a Rayleigh process, and (2) the maxima in the centres of the San Francisco and San Nicolas orebodies are explained by mixing of the S transporting hydrothermal fluids with seawater within the sediments. Associated pyrite and cinnabar were deposited under isotopic disequilibrium, probably because the low solubility of cinnabar caused rapid precipitation of cinnabar. The different morphological pyrite types have their own isotopic δ34S signatures. The spilites are notably enriched in S ( n = 3; average S content = 0.56%) compared to normal basalts (1000 ppm) and have an average δ34S = 5.1 ± 1.3%.. The linear relationship between the δ34S and the S content of the spilites is interpreted as a mixing line between mantle S and a constant S source, probably an infinite open reservoir. An incomplete basalt-seawater reaction at nearly constant temperature is the best explanation for this relation. The S (predominantly pyrite) of the black shales ( n = 3; δ34S

  4. Environment of ore deposition in the Creede mining district, San Juan Mountains, Colorado: Part VI. Maximum duration for mineralization of the OH vein

    USGS Publications Warehouse

    Campbell, W.R.; Barton, P.B.

    2005-01-01

    The rate at which ore deposits form is one of the least well established parameters in all of economic geology. However, increased detail in sampling, improved technology of dating, and sophistication in modeling are reducing the uncertainties and establishing that ore formation, at least for the porphyry copper-skarn-epithermal base and precious metals deposit package, may take place in surprisingly brief intervals. This contribution applies another approach to examine the duration of mineralization. The degree to which compositional gradients within single crystals has flattened through solid-state diffusion offers a measure of the thermal dose (that is temperature combined with time) that the crystals have been subjected to since deposition. Here we examine the steepness of gradients in iron content within individual single sphalerite crystals from the epithermal silver-lead-zinc deposit in the OH vein at Creede, Colorado. Two initial textures are considered: growth-banded crystals and compositionally contrasting overgrowths that succeed crosscutting dissolution or fractured surfaces. The model used estimates the maximum possible time by assuming a perfectly sharp original compositional step, and it asks how long it would take at a known temperature for the gradient measured today to have formed. Applying the experimentally determined diffusion rates of Mizuta (1988a) to compositional gradients (ranging from 0.4-2.2 mol % FeS/??m) measured by the electron microprobe in 2-??m steps on banded sphalerite formed early in the paragenetic history yields a maximum duration of less than ???10,000 yr. Sphalerite from a solution unconformity in a position midway through the paragenetic sequence is indistinguishable from instantaneous deposition, supporting the conclusion of rapid ore formation. While this formation interval seems very brief, it is consistent with less well constrained estimates using entirely different criteria. ?? 2005 Society of Economic Geologists, Inc.

  5. Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: potential use in environmental risk assessment.

    PubMed

    Neves, Natália Rust; Oliva, Marco Antonio; da Cruz Centeno, Danilo; Costa, Alan Carlos; Ribas, Rogério Ferreira; Pereira, Eduardo Gusmão

    2009-06-01

    The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM(Fe)) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM(Fe) application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers.

  6. Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: potential use in environmental risk assessment.

    PubMed

    Neves, Natália Rust; Oliva, Marco Antonio; da Cruz Centeno, Danilo; Costa, Alan Carlos; Ribas, Rogério Ferreira; Pereira, Eduardo Gusmão

    2009-06-01

    The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM(Fe)) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM(Fe) application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers. PMID:19321190

  7. Introduction to ore geology

    SciTech Connect

    Evans, A.M.

    1987-01-01

    This textbook on ore geology is for second and third year undergraduates and closely parallels the undergraduate course given in this subject at England's University of Leicester. The volume covers three major areas: (1) principles of ore geology, (2) examples of the most important types of ore deposits, and (3) mineralization in space and time. Many chapters have been thoroughly revised for this edition and a chapter on diamonds has been added. Chapters on greisen and pegmatite have also been added, the former in response to the changing situation in tin mining following the recent tin crisis, and the latter in response to suggestions from geologists in a number of overseas countries. Some chapters have been considerably expanded and new sections added, including disseminated gold deposits and unconformity-associated uranium deposits. The author also expands on the importance of viewing mineral deposits from an economic standpoint.

  8. Geological, fluid inclusion and isotopic studies of the Yinshan Cu-Au-Pb-Zn-Ag deposit, South China: Implications for ore genesis and exploration

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Guang; Ni, Pei; Wang, Ru-Cheng; Zhao, Kui-Dong; Chen, Hui; Ding, Jun-Ying; Zhao, Chao; Cai, Yi-Tao

    2013-09-01

    The Yinshan Cu-Au-Pb-Zn-Ag deposit is located in Dexing, South China. Ore bodies are primarily hosted in low-grade phyllite of the Neoproterozoic Shuangqiaoshan Group along EW- and NNW-striking fault zones. Pb-Zn-Ag mineralization is dictated by Jurassic rhyolitic quartz porphyries (ca. 172 Ma), whereas Cu-Au mineralization is associated with Jurassic dacite porphyries (ca. 170 Ma). The main ore minerals are pyrite, chalcopyrite, galena, sphalerite, tetrahedrite-tennatite, gold, silver, and silver sulphosalt, and the principal gangue minerals are quartz, sericite, calcite, and chlorite. Two-phase liquid-rich (type I), two-phase vapor-rich (type II), and halite-bearing (type III) fluid inclusions can be observed in the hydrothermal quartz-sulfides veins. Type I inclusions are widespread and have homogenization temperatures of 187-303 °C and salinities of 4.2-9.5 wt.% NaCl equivalent in the Pb-Zn-Ag mineralization, and homogenization temperatures of 196-362 °C and salinities of 3.5-9.9 wt.% NaCl equivalent in the Cu-Au mineralization. The pervasive occurrence of type I fluid inclusions with low-moderate temperatures and salinities implies that the mineralizing fluids formed in epithermal environments. The type II and coexisting type III inclusions, from deeper levels below the Cu-Au ore bodies, share similar homogenization temperatures of 317-448 °C and contrasting salinities of 0.2-4.2 and 30.9-36.8 wt.% NaCl equivalent, respectively, which indicates that boiling processes occurred. The sulfur isotopic compositions of sulfides (δ34S = -1.7‰ to +3.2‰) suggest a homogeneous magmatic sulfur source. The lead isotopes of sulfides (206Pb/204Pb = 18.01-18.07; 207Pb/204Pb = 15.55-15.57; and 208Pb/204Pb = 38.03-38.12) are consistent with those of volcanic-subvolcanic rocks (206Pb/204Pb = 18.03-18.10; 207Pb/204Pb = 15.56-15.57; and 208Pb/204Pb = 38.02-38.21), indicating a magmatic origin for lead in the ore. The oxygen and hydrogen isotope compositions (δ18O = +7.8

  9. Source of ore-forming fluids of the Tianbaoshan Pb-Zn deposit, Southwest China: constrains from C-O, S, and He-Ar isotopes

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zhang, Jun; Zhong, Wenbin

    2016-04-01

    The Sichuan-Yunnan-Guizhou (SYG) metallogenic province is one of the most important areas for Pb-Zn resources in China. The metallogenic sources of these Pb-Zn deposits have long been debated. In this study, we provide integrated C-O-S-He-Ar isotopic data of the typical Tianbaoshan Pb-Zn deposit, with an aim to constrain the sources of ore-forming fluids. The Tianbaoshan deposit a large-sized Pb-Zn deposit in SYG metallogenic province, Southwest China. The proven resources include 2.6 Mt metals of Zn+Pb with average grades of 10.09% Zn and 1.50% Pb. The orebodies are hosted within the carbonates of the Ediacaran Dengying Formation. Ore minerals consist mainly of sphalerite, galena, chalcopyrite, and pyrite. Gangue minerals are dominated by calcite and dolomite. The calcite samples from the Tianbaoshan deposit yield homogeneous δ13CV ‑PDBvalues of -1.70‰ to -1.60‰ (average -1.63), with δ18OV ‑SMOW values ranging from 12.9‰ to 15.2‰ (average 14.4). The C-O isotopic data suggest the hydrothermal fluids may be originated from a mixed source involving both mantle and carbonate wall rocks. The δ34S values of the sphalerite, galena and chalcopyrite samples vary from 3.32‰ to 5.71‰ -0.36‰ to 1.31‰ and 4.5‰ to 4.7‰ respectively, indicating a magmatic source for sulfur. The 3He/4He ratios of chalcopyrite samples range from 0.01 to 0.32 Ra which is slightly higher than the crustal ratios (0.05 Ra), but obviously lower than that of mantle fluids (6 to 9 Ra). The 40Ar/36Ar ratios range from 345.0 to 669.1, which are slightly higher than that of air (298.5). The He-Ar isotopic compositions suggest that the ore-forming fluids are dominantly derived from the crust, with litter contamination from mantle-derived fluids. In combination with the C-O, S, and He-Ar isotopic data, we propose the ore-forming fluids of the Tianbaoshan deposit were derived by mixing of crustal and mantle fluids. And the metallogenic process may be genetically related to the

  10. Regional Crustal Structures and Their Relationship to the Distribution of Ore Deposits in the Western United States, Based on Magnetic and Gravity Data

    USGS Publications Warehouse

    Hildenbrand, T.G.; Berger, B.; Jachens, R.C.; Ludington, S.

    2000-01-01

    Upgraded gravity and magnetic databases and associated filtered-anomaly maps of western United States define regional crustal fractures or faults that may have guided the emplacement of plutonic rocks and large metallic ore deposits. Fractures, igneous intrusions, and hydrothermal circulation tend to be localized along boundaries of crustal blocks, with geophysical expressions that are enhanced here by wavelength filtering. In particular, we explore the utility of regional gravity and magnetic data to aid in understanding the distribution of large Mesozoic and Cenozoic ore deposits, primarily epithermal and porphyry precious and base metal deposits and sediment-hosted gold deposits in the western United States cordillera. On the broadest scale, most ore deposits lie within areas characterized by low magnetic properties. The Mesozoic Mother Lodge gold belt displays characteristic geophysical signatures (regional gravity high, regional low-to-moderate background magnetic field anomaly, and long curvilinear magnetic highs) that might serve as an exploration guide. Geophysical lineaments characterize the Idaho-Montana porphyry belt and the La Caridad-Mineral Park belt (from northern Mexico to western Arizona) and thus indicate a deep-seated control for these mineral belts. Large metal accumulations represented by the giant Bingham porphyry copper and the Butte polymetallic vein and porphyry copper systems lie at intersections of several geophysical lineaments. At a more local scale, geophysical data define deep-rooted faults and magmatic zones that correspond to patterns of epithermal precious metal deposits in western and northern Nevada. Of particular interest is an interpreted dense crustal block with a shape that resembles the elliptical deposit pattern partly formed by the Carlin trend and the Battle Mountain-Eureka mineral belt. We support previous studies, which on a local scale, conclude that structural elements work together to localize mineral deposits within

  11. Coupled Heat and Fluid Flow Modeling of the Earth's Largest Zinc Ore Deposit at Red Dog, Alaska: Implications for Structurally-Focused, Free Convection in Submarine Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Garven, G.; Dumoulin, J. A.; Bradley, D. A.; Young, L. E.; Kelley, K. D.; Leach, D. L.

    2002-12-01

    Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in submarine basins where other mechanisms for driving pore fluid flow such as topography, compaction and crustal deformation are too weak or too slow to have a significant effect on disturbing conductive heat flow. Fault zones appear to play a crucial role in focusing fluid migration in basins, as inferred in ancient rocks by many examples of hydrothermal deposits of sediment-hosted ores worldwide. Many rift-hosted deposits of lead, zinc, and barite ore appear to have formed at or near the seafloor by focused venting of hot basinal fluids and modified seawater, although the geophysical nature of these systems is not so well known. For example, the upper Kuna Formation, a finely laminated, black, organic-rich siliceous mudstone and shale in the Western Brooks Range of northwest Alaska, is host to the largest resources of zinc yet discovered in the Earth's crust, containing ore reserves in excess of 175 Mt averaging about 16% Zn and 5% Pb. Although situated today in a highly-deformed series of structural allocthonous plates thrusted during the Jurassic to Cretaceous Brookian Orogeny, the stratiform ores are thought to have formed much earlier in the anoxic, mud-rich Carboniferous-age Kuna Basin when adjacent carbonate platforms were drowned by rifting and tectonic subsidence. Fluid inclusion studies of ore-stage sphalerite and gangue minerals indicate sub-seafloor mineralization temperatures less than 200oC and most likely between 120 to 150 oC, during a period of sediment diagenesis and extensional faulting. We have constructed fully-coupled numerical models of heat and fluid flow to test hydrologic theories for free convection, submarine venting and subsequent ore formation, as constrained by paleoheat flow and petrologic observations. A finite element grid was designed and adapted for a cross section of the Kuna Basin, geologically restored to latest Mississippian time

  12. The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications

    USGS Publications Warehouse

    Viets, J.G.; Hofstra, A.H.; Emsbo, P.; Kozlowski, A.

    1996-01-01

    The composition of fluids extracted from ore and gangue sulfide minerals that span most of the paragenesis of the Silesian-Cracow district was determined using a newly developed ion chromatographic (IC) technique. Ionic species determined were Na+, NH+4, Ca2+, Mg2+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, F-, I-, PO3-4, CO2-3, HS-, S2O2-3, SO2-4, NO-3, and acetate. Mineral samples included six from the Pomorzany mine and one from the Trzebionka mine which are hosted in the Triassic Muschelkalk Formation, and two samples of drill core from mineralized Upper Devonian strata. Nine paragenetically identifiable sulfide minerals occur throughout the Silesian-Cracow district. These include from earliest to latest: early iron sulfides, granular sphalerite, early galena, light-banded sphalerite, galena, dark-banded sphalerite, iron sulfides, late dark-banded sphalerite with late galena, and late iron sulfides. Seven of the minerals were sampled for fluid inclusion analysis in this study. Only the early iron sulfides and the last galena stage were not sampled. Although the number of analyses are limited to nine samples and two replicates and there is uncertainty about the characteristics of the fluid inclusions analyzed, the data show clear temporal trends in the composition of the fluids that deposited these minerals. Fluid inclusions in minerals deposited later in the paragenesis have significantly more K+, Br-, NH+4, and acetate but less Sr2+ than those deposited earlier in the paragenesis. The later minerals are also characterized by isotopically lighter sulfur and significantly more Tl and As in the solid minerals. The change in ore-fluid chemistry is interpreted to reflect a major change in the hydrologic regime of the district. Apparently, the migrational paths of ore fluids from the Upper Silesian basin changed during ore deposition and the fluids which deposited early minerals reacted with aquifers with very different geochemical characteristics than those that deposited

  13. An investigation into heterogeneity in a single vein-type uranium ore deposit: Implications for nuclear forensics.

    PubMed

    Keatley, A C; Scott, T B; Davis, S; Jones, C P; Turner, P

    2015-12-01

    Minor element composition and rare earth element (REE) concentrations in nuclear materials are important as they are used within the field of nuclear forensics as an indicator of sample origin. However recent studies into uranium ores and uranium ore concentrates (UOCs) have shown significant elemental and isotopic heterogeneity from a single mine site such that some sites have shown higher variation within the mine site than that seen between multiple sites. The elemental composition of both uranium and gangue minerals within ore samples taken along a single mineral vein in South West England have been measured and reported here. The analysis of the samples was undertaken to determine the extent of the localised variation in key elements. Energy Dispersive X-ray spectroscopy (EDS) was used to analyse the gangue mineralogy and measure major element composition. Minor element composition and rare earth element (REE) concentrations were measured by Electron Probe Microanalysis (EPMA). The results confirm that a number of key elements, REE concentrations and patterns used for origin location do show significant variation within mine. Furthermore significant variation is also visible on a meter scale. In addition three separate uranium phases were identified within the vein which indicates multiple uranium mineralisation events. In light of these localised elemental variations it is recommended that representative sampling for an area is undertaken prior to establishing the REE pattern that may be used to identify the originating mine for an unknown ore sample and prior to investigating impact of ore processing on any arising REE patterns. PMID:26301831

  14. An investigation into heterogeneity in a single vein-type uranium ore deposit: Implications for nuclear forensics.

    PubMed

    Keatley, A C; Scott, T B; Davis, S; Jones, C P; Turner, P

    2015-12-01

    Minor element composition and rare earth element (REE) concentrations in nuclear materials are important as they are used within the field of nuclear forensics as an indicator of sample origin. However recent studies into uranium ores and uranium ore concentrates (UOCs) have shown significant elemental and isotopic heterogeneity from a single mine site such that some sites have shown higher variation within the mine site than that seen between multiple sites. The elemental composition of both uranium and gangue minerals within ore samples taken along a single mineral vein in South West England have been measured and reported here. The analysis of the samples was undertaken to determine the extent of the localised variation in key elements. Energy Dispersive X-ray spectroscopy (EDS) was used to analyse the gangue mineralogy and measure major element composition. Minor element composition and rare earth element (REE) concentrations were measured by Electron Probe Microanalysis (EPMA). The results confirm that a number of key elements, REE concentrations and patterns used for origin location do show significant variation within mine. Furthermore significant variation is also visible on a meter scale. In addition three separate uranium phases were identified within the vein which indicates multiple uranium mineralisation events. In light of these localised elemental variations it is recommended that representative sampling for an area is undertaken prior to establishing the REE pattern that may be used to identify the originating mine for an unknown ore sample and prior to investigating impact of ore processing on any arising REE patterns.

  15. The source of phosphate in the oxidation zone of ore deposits: Evidence from oxygen isotope compositions of pyromorphite

    NASA Astrophysics Data System (ADS)

    Burmann, Fabian; Keim, Maximilian F.; Oelmann, Yvonne; Teiber, Holger; Marks, Michael A. W.; Markl, Gregor

    2013-12-01

    Pyromorphite (Pb5[PO4]3Cl) is an abundant mineral in oxidized zones of lead-bearing ore deposits and due to its very low solubility product effectively binds Pb during supergene alteration of galena (PbS). The capacity of a soil or near-surface fluid to immobilize dissolved Pb depends critically on the availability of phosphate in this soil or fluid. Potential phosphorus sources in soil include (i) release during biological processes, i.e. leaching from litter/lysis of microbial cells (after intracellular enzyme activity) in soil and hydrolysis from soil organic matter by extracellular enzymes and (ii) inorganic phosphate from the dissolution of apatite in the adjacent basement rocks. Intracellular enzyme activity in plants/microorganisms associated with kinetic fractionation produces an oxygen isotope composition distinctly different from inorganic processes in soil. This study presents the first oxygen isotope data for phosphate (δ18OP) in pyromorphite and a comprehensive data set for apatite from crystalline rocks. We investigated 38 pyromorphites from 26 localities in the Schwarzwald (Southwest Germany) and five samples from localities outside the Schwarzwald in addition to 12 apatite separates from gneissic and granitic host rocks. Pyromorphites had δ18OP values between +10‰ and +19‰, comparable to literature data on δ18OP in the readily available P fraction in soil (resin-extractable P) from which minerals potentially precipitate in soils. δ18OP values below the range of equilibrium isotope fractionation can be attributed either to apatites that formed geochemically (δ18OP of apatites:+6‰ to +9‰) or less likely to biological processes (extracellular enzyme activity). However, for most of our samples isotopic equilibrium with ambient water was indicated, which suggests biological activity. Therefore, we conclude that the majority of pyromorphites in oxidized zones of ore bodies formed from biologically cycled phosphate. This study highlights that

  16. Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada

    USGS Publications Warehouse

    Rytuba, James J.; John, David A.; Foster, Andrea; Ludington, Steven D.; Kotlyar, Boris

    2003-01-01

    Gallium is produced as a byproduct from bauxite and zinc sulfide ores and rarely from primary Ga ores. High Ga contents (>60 ppm) can occur in zones of advanced argillic alteration consisting of alunite+kaolinite+quartz associated with quartz-alunite (high sulfidation Au-Ag) deposits. In a magmatic-hydrothermal environment, the zones of advanced argillic alteration associated with quartz-alunite (high sulfidation) Au-Ag deposits have the highest Ga contents (max 120 ppm). In these Au deposits, Ga is enriched in the zone of alunite+kaolinite alteration and depleted in the zone of quartz-rich alteration within acid-leached rocks. Peripheral zones of argillic alteration have Ga contents and Al/Ga ratios similar to those in unaltered volcanic rocks. The zones of advanced argillic alteration that formed in a steam-heated environment in association with hot-spring-type Hg-Au deposits are not Ga enriched, and residual silicified zones have very low Ga contents. The McDermitt Hg and Paradise Peak Au-Hg deposits, Nev., have zones of advanced argillic alteration that are Ga enriched. At the Paradise Peak Au-Hg deposits, Ga is enriched in the zone of alunite+jarosite alteration that formed in a magmatic-hydrothermal environment. Ga is depleted in the zone of opal+alunite alteration formed in a steam-heated environment, in residual silicified zones formed in a magmatic-hydrothermal environment, and in zones of supergene jarosite alteration. At the McDermitt Hg deposit, Ga is enriched in the zone of alunite+kaolinite alteration below the zone of adularia-quartz alteration that coincides with the Hg ore body. The spatial relation of Ga enrichment to alunite-kaolinite alteration suggests that formation in a magmatic-hydrothermal environment. X-ray-absorption spectra of Ga-enriched samples from the McDermitt Hg deposit are similar to that of gallium sulfate and support the association of Ga enrichment with alunite alteration.

  17. Evolution of Ore Deposits and Technology Transfer Project: Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008

    USGS Publications Warehouse

    Rye, Robert O.; Johnson, Craig A.; Landis, Gary P.; Hofstra, Albert H.; Emsbo, Poul; Stricker, Craig A.; Hunt, Andrew G.; Rusk, Brian G.

    2010-01-01

    Principal functions of the U.S. Geological Survey (USGS) Mineral Resources Program are providing assessments of the location, quantity, and quality of undiscovered mineral deposits, and predicting the environmental impacts of exploration and mine development. The mineral and environmental assessments of domestic deposits are used by planners and decisionmakers to improve the stewardship of public lands and public resources. Assessments of undiscovered mineral deposits on a global scale reveal the potential availability of minerals to the United States and other countries that manufacture goods imported to the United States. These resources are of fundamental relevance to national and international economic and security policy in our globalized world economy. Performing mineral and environmental assessments requires that predictions be made of the likelihood of undiscovered deposits. The predictions are based on geologic and geoenvironmental models that are constructed for the diverse types of mineral deposits from detailed descriptions of actual deposits and detailed understanding of the processes that formed them. Over the past three decades the understanding of ore-forming processes has benefited greatly from the integration of laboratory-based geochemical tools with field observations and other data sources. Under the aegis of the Evolution of Ore Deposits and Technology Transfer Project (referred to hereinafter as the Project), a 5-year effort that terminated in 2008, the Mineral Resources Program provided state-of-the-art analytical capabilities to support applications of several related geochemical tools to ore-deposit-related studies. The analytical capabilities and scientific approaches developed within the Project have wide applicability within Earth-system science. For this reason the Project Laboratories represent a valuable catalyst for interdisciplinary collaborations of the type that should be formed in the coming years for the United States to meet

  18. Hydrothermal alteration of organic matter in uranium ores, Elliot Lake, Canada: Implications for selected organic-rich deposits

    SciTech Connect

    Mossman, D.J.; Nagy, B.; Davis, D.W.

    1993-07-01

    Organic matter in the uraniferous Matinenda Formation, Elliot Lake, is preserved in the forms of syngenetic kerogen and solid bitumen as it is in many of the Oklo uranium deposits and in the Witwatersrand gold-uranium ores. The Elliot Lake kerogen is a vitrinite-like material considered to be remnants of the Precambrian cyanobacterial mats. The kerogen at Elliot Lake has reflectances (in oil) ranging from 2.63-7.31% RO{sub max}, high aromaticity, relatively low (0.41-0.60) atomic H/C ratios, and it contains cryptocrystalline graphite. Bitumen, present primarily as dispersed globules (up to 0.5 mm dia.), has reflectances from 0.72-1.32% RO{sub max}, atomic H/C ratios of 0.71-0.81, and is somewhat less aromatic than the kerogen. Overall similarity in molecular compositions indicates that liquid bitumen was derived from kerogen by processes similar to hydrous pyrolysis. The carbon isotopic composition of kerogen ({minus}15.62 to {minus}24.72%), and the now solid bitumen ({minus}25.91 to {minus}33.00%) are compatible with these processes. Despite having been subjected to several thermal episodes, ca. 2.45 Ga old kerogen of microbiological origin here survived as testimony of the antiquity of life on Earth. U-Pb isotopic data from discrete kerogen grains at Elliot Lake form a scattered array intersecting concordia at 2130 {+-} 100 Ma, correspond to the Nipissing event. U-Pb systems were totally reset by this event. Uranium and lead show subsequently partial mobility, the average of which is indicated by the lower concordia intersect of 550 {+-} 260 Ma. The migrated bitumen contains virtually no uranium and thorium but has a large excess of {sup 206}Pb, which indicates that the once liquid bitumen must have acted as a sink for mobile intermediate decay products of {sup 238}U. Emplacement of the Nipissing diabase may have been responsible for producing the bitumen and, indirectly, for its enrichment in {sup 206}Pb as a result of outgassing of {sup 222}Rn.

  19. Mineralogical and geochemical constraints on environmental impacts from waste rock at Taojiang Mn-ore deposit, central Hunan, China

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Piestrzynski, Adam; Pieczonka, Jadwiga; Xiao, Meilian; Wang, Yaozhu; Xie, Shurong; Tang, Xiaoyan; Yu, Changxun; Song, Zhi

    2007-07-01

    The mineralogy and geochemistry of the waste rocks distributed at Taojiang Mn-ore deposit, central Hunan province, China, were studied using X-ray powder diffraction (XRD), electron microprobe analysis (EMPA) fitted with energy dispersive spectrometer (EDS) and inductively coupled plasma mass spectrum (atomic emission spectra) ICP-MS (AES), with the aim of predicting the environmental impacts of weathering of the waste rocks. The mineralogical results from microscope observation and XRD and EMPA studies show that the waste rock is composed of black shale and minor Mn carbonates. The oxidation of sulfide minerals such as galena, pyrite and chalcopyrite is accompanied by decomposition of Mn carbonates and K-feldspar during exposure to atmospheric O2. The geochemical characteristics of major, rare earth elements (REE) and trace elements of the waste rocks also show that the waste rock can be divided into black shale and Mn carbonate, and both of them are currently under chemical weathering. The major alkalies and alkaline elements (Ca, Mg, Na, K, Rb, Sr and Cs) and major elements (Fe, S and P) and heavy metals (Sc, V, Cr, Th, U, Sn, Co, Ni, Cu, Zn, Pb, Mo, Cd, Sb, an Tl) are being released during weathering. The mobility of alkalis and alkaline elements Ca, Mg, Na, K, Rb, Sr and Cs is controlled by decomposition of Mn carbonates. The dispersion of Cr, Sc and Th (U) might be related to weathering of K-feldspar, and the release of the heavy metals Co, Ni, Cu, Zn, Pb, Mo, Cd Sb and Tl is dominated by the breaking of sulfide minerals. The REE of the waste rocks and surrounding soils and the spidery distribution patterns of heavy metals in the waste rocks, the surrounding soils and the surface waters show that weathering of the waste rocks and bedrock might be the sources of heavy metal contamination for the surrounding soils and surface water system for the mining area. This is predicted by the mass-balance calculation by using Zr as an immobile element. Therefore, it is

  20. Petrogenesis of Paleocene-Eocene porphyry deposit-related granitic rocks in the Yaguila-Sharang ore district, central Lhasa terrane, Tibet

    NASA Astrophysics Data System (ADS)

    Zhao, Junxing; Li, Guangming; Evans, Noreen J.; Qin, Kezhang; Li, Jinxiang; Zhang, Xia'nan

    2016-11-01

    The Paleocene-Eocene ore deposits in the Gangdese Metallogenic Belt, Tibet, are thought to have been formed during the main period of India-Asia continental collision. This paper reports the whole-rock major element, trace element, and Sr-Nd-Hf isotopic compositions and zircon trace element contents of volcanic and intrusive rocks from the Paleocene Yaguila skarn Pb-Zn-Ag deposit and adjacent Eocene Sharang porphyry Mo deposit in the central Lhasa terrane, Tibet. Geochemical signatures and Nd-Hf isotopic compositions indicate that the Yaguila Cretaceous rhyolitic rocks were formed by the melting of ancient continental crust, whereas the Paleocene causative granite porphyry may have resulted from the interaction between mantle-derived and crustal-derived materials when continental collision was initiated. The dramatic increase of εNd(t) values between emplacement of the granite porphyry and later porphyritic biotite granite suggests a greater involvement of mantle materials during the crystallization of the barren biotite granite stock. The post-ore Miocene granodiorite porphyry has a similar geochemical signature to the Sharang Miocene dykes, suggesting they were both generated from melting of enriched lithospheric mantle. Nd-Hf mixing calculations indicate an increasing contribution of mantle materials in Paleocene to Eocene intrusions, consistent with the regional tectonic model of Neo-Tethyan oceanic slab roll-back and break-off. Zircons from both the Yaguila and Sharang ore-related porphyries have higher Ce anomalies than those from the barren granitoids, suggesting that Mo mineralization was closely related to highly oxidized and differentiated magma. The fertile intrusions in the Yaguila-Sharang district contain EuN/EuN∗ values from 0.3 to 0.6, higher than the non-mineralized intrusions. The processes of early crystallization of plagioclase and/or SO2-degassing from underlying magma can explain the observed negative Eu anomalies in zircon.

  1. Numerical investigation of salinity in controlling ore-forming fluid transport in sedimentary basins: example of the HYC deposit, Northern Australia

    NASA Astrophysics Data System (ADS)

    Yang, Jianwen; Bull, Stuart; Large, Ross

    2004-10-01

    This paper presents the first hydrogeological model that fully couples transient fluid flow, heat and solute transport associated with the formation of the HYC SEDEX deposit in the McArthur Basin, northern Australia. Numerical results reveal that salinity plays an important role in controlling hydrothermal fluid migration. In particular, it appears that it is the distribution of evaporitic units within a given basin, rather than their absolute abundance, that controls the development of free convection. Relatively saline conditions at the seafloor strengthen the thermally-induced buoyancy force and hence promote free convection of basinal solutions; whereas high salinities at the bottom counteract the thermal function of natural geothermal gradient and suppress the development of convective hydrothermal fluid circulation. In the latter case, higher thermal gradients are required to initiate substantial free convective fluid flow. Numerical experiments also suggest the position of an ore body with respect to its vent system may be controlled by the spatial and temporal salinity distributions in the basin. Vent-distal ore formation, a result of exhalation of brines that are denser than seawater and hence can flow away from the vent region, is promoted by moderate salinity at the seafloor and higher salinity in the aquifer. Vent-proximal ore accumulation, a result of pluming upon exhalation of brines less dense than seawater, is favored by the highest salinity conditions occurring near the level of the seafloor.

  2. Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit, New Caledonia)

    NASA Astrophysics Data System (ADS)

    Cathelineau, Michel; Quesnel, Benoît; Gautier, Pierre; Boulvais, Philippe; Couteau, Clément; Drouillet, Maxime

    2016-02-01

    In New Caledonian Ni deposits, the richest Ni silicate ores occur in fractures within the bedrock and saprolite, generally several tens of meters to hundred meters below the present-day surface. Fracture-related Ni silicate ore accounts for high Ni grades, at least a few weight percent above the average exploited grade (2.5 %). These Ni-rich veins are affected by active dissolution-precipitation processes at the level of the water table. Ni in solution is precipitated as silicates in thin layer cementing joints. This mineralization is characterized by chemical and mineralogical concentric zoning with an outer green rim around an inner white zone composed, from the edge to the centre of the block, (i) a highly oxidized and altered zone, (ii) a green pure Ni-rich pimelite zone, (iii) a zone (limited to a few centimetres) with a mixture of Ni-poor kerolite and Ni-rich pimelite and intermediate colours and (iv) a large white Mg-kerolite mineralization zone. This study proposes that the concentric zonation results from evapo-precipitation process related to alternate periods of hydration and drying, induced by water table movements. This extensive dispersion of Ni in concentrically zoned ores can partly explain the rather monotonous Ni grade of the bulk exploitation at the base of the regolith with values between 2 and 3 wt%.

  3. Strontium isotope constraint on the genesis of crude oils, oil-field brines and Kuroko ore deposits from the Green Tuff region of northeastern Japan

    NASA Astrophysics Data System (ADS)

    Nakano, Takanori; Kajiwara, Yoshimichi; Farrell, Clifton W.

    1989-10-01

    Crude oils from Akita to northern Niigata oil fields in the Green Tuff region of northeastern Japan have distinctly uniform 87Sr/86Sr ratios (0.7080-0.7082), while those from the southern Niigata oil field contain more radiogenic strontium (0.7095-0.7102). The regional variation in the strontium isotopic composition of crude oils is also reflected in their sulfur contents and sulfur isotopic compositions, and may be attributed to the regional heterogeneity of marine organic sediments from which the crude oils were ultimately derived. The 87Sr/86Sr ratios of most oil-field brines (0.7061-0.7084), however, are different from and vary more locally than those of the accompanying crude oils. This finding supports the view that strontium, and by inference some other dissolved solutes in the brines, may have evolved during diagenesis by reaction of a connate and/or a meteoric water with rocks in the Green Tuff region. Barites in the sulfide ore and anhydrites and gypsums in the sulfate (sekko) ore from the Fukazawa and Kosaka Kuroko deposits in the Hokuroku district are divided by the 87Sr/86Sr ratio of 0.7081 (±0.0001), which is identical to that of crude oils from nearby oil fields. This similarity in ratios lends support to the conclusion that the Kuroko base metal deposits and crude oil deposits were ultimately derived from a common organic sediment named PUMOS (Primitive Undifferentiated Metalliferous Organic Sediments).

  4. The Sarylakh and Sentachan gold-antimony deposits, Sakha-Yakutia: A case of combined mesothermal gold-quartz and epithermal stibnite ores

    NASA Astrophysics Data System (ADS)

    Bortnikov, N. S.; Gamynin, G. N.; Vikent'eva, O. V.; Prokof'ev, V. Yu.; Prokop'ev, A. V.

    2010-10-01

    New mineralogical, thermobarometric, isotopic, and geochemical data provide evidence for long and complex formation history of the Sarylakh and Sentachan Au-Sb deposits conditioned by regional geodynamics and various types of ore mineralization, differing in age and source of ore matter combined in the same ore-localizing structural units. The deposits are situated in the Taryn metallogenic zone of the East Yakutian metallogenic belt in the central Verkhoyansk-Kolyma Fold Region. They are controlled by the regional Adycha-Taryn Fault Zone that separates the Kular-Nera Terrane and the western part of the Verkhoyansk Fold-Thrust Belt. The fault extends along the strike of the northwest-trending linear folds and is deep-rooted and repeatedly reactivated. The orebodies are mineralized crush zones accompanied by sulfidated (up to 100 m wide) quartz-sericite metasomatic rocks and replacing dickite-pyrophyllite alteration near stibnite veinlets. Two stages of low-sulfide gold-quartz and stibnite mineralization are distinguished. The formation conditions of the early milk white quartz in orebodies with stibnite mineralization at the Sarylakh and Sentachan deposits are similar: temperature interval 340-280°C, salt concentration in fluids 6.8-1.6 wt % NaCl equiv, fluid pressure 3430-1050 bar, and sodic bicarbonate fluid composition. The ranges of fluid salinity overlapped at both deposits. In the late regenerated quartz that attends stibnite mineralization, fluid inclusions contain an aqueous solution with salinity of 3.2 wt % NaCl equiv and are homogenized into liquid at 304-189°C. Syngenetic gas inclusions contain nitrogen 0.19 g/cm3 in density. The pressure of 300 bar is estimated at 189°C. The composition of the captured fluid is characterized as K-Ca bicarbonatesulfate. The sulfur isotopic composition has been analyzed in pyrite and arsenopyrite from ore and metasomatic zones, as well as in coarse-, medium-, and fine-grained stibnite varieties subjected to

  5. Genesis of massive sulfide deposits in the Verkhneural'sk ore district, the South Urals, Russia: Evidence for magmatic contribution of metals and fluids

    NASA Astrophysics Data System (ADS)

    Karpukhina, V. S.; Naumov, V. B.; Vikent'ev, I. V.

    2013-03-01

    Melt inclusions and aqueous fluid inclusions in quartz phenocrysts from host felsic volcanics, as well as fluid inclusions in minerals of ores and wall rocks were studied at the Cu-Zn massive sulfide deposits in the Verkhneural'sk ore district, the South Urals. The high-temperature (850-1210°C) magmatic melts of volcanic rocks are normal in alkalinity and correspond to rhyolites of the tholeiitic series. The groups of predominant K-Na-type (K2O/Na2O = 0.3-1.0), less abundant Na-type (K2O/Na2O = 0.15-0.3), and K-type (K2O/Na2O = 1.9-9.3) rhyolites are distinguished. The average concentrations (wt %) of volatile components in the melts are as follows: 2.9 H2O (up to 6.5), 0.13 Cl (up to 0.28), and 0.09 F (up to 0.42). When quartz was crystallizing, the melt was heterogeneous, contained magnetite crystals and sulfide globules (pyrrhotite, pentlandite, chalcopyrite, bornite). High-density aqueous fluid inclusions, which were identified for the first time in quartz phenocrysts from felsic volcanics of the South Urals, provide evidence for real participation of magmatic water in hydrothermal ore formation. The fluids were homogenized at 124-245°C in the liquid phase; the salinity of the aqueous solution is 1.2-6.2 wt % NaCl equiv. The calculated fluid pressure is very high: 7.0-8.7 kbar at 850°C and 5.1-6.8 kbar at 700°C. The LA-ICP-MS analysis of melt and aqueous fluid inclusions in quartz phenocrysts shows a high saturation of primary magmatic fluid and melt with metals. This indicates ore potential of island-arc volcanic complexes spatially associated with massive sulfide deposits. The systematic study of fluid inclusions in minerals of ores and wall rocks at five massive sulfide deposits of the Verkhneural'sk district furnished evidence that ore-forming fluids had temperature of 375-115°C, pressure up to 1.0-0.5 kbar, chloride composition, and salinity of 0.8-11.2 (occasionally up to 22.8) wt % NaCl equiv. The H and O isotopic compositions of sericite from host

  6. Leaching of silica bands and concentration of magnetite in Archean BIF by hypogene fluids: Beebyn Fe ore deposit, Yilgarn Craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Duuring, Paul; Hagemann, Steffen

    2013-03-01

    The ~2,752-Ma Weld Range greenstone belt in the Yilgarn Craton of Western Australia hosts several Fe ore deposits that provide insights into the role of early hypogene fluids in the formation of high-grade (>55 wt% Fe) magnetite-rich ore in banded iron formation (BIF). The 1.5-km-long Beebyn orebody comprises a series of steeply dipping, discontinuous, <50-m-thick lenses of magnetite-(martite)-rich ore zones in BIF that extend from surface to vertical depths of at least 250 m. The ore zones are enveloped by a 3-km-long, 150-m-wide outer halo of hypogene siderite and ferroan dolomite in BIF and mafic igneous country rocks. Ferroan chlorite characterises 20-m-wide proximal alteration zones in mafic country rocks. The magnetite-rich Beebyn orebody is primarily the product of hypogene fluids that circulated through reverse shear zones during the formation of an Archean isoclinal fold-and-thrust belt. Two discrete stages of hypogene fluid flow caused the pseudomorphic replacement of silica-rich bands in BIF by Stage 1 siderite and magnetite and later by Stage 2 ferroan dolomite. The resulting carbonate-altered BIF is markedly depleted in SiO2 and enriched in CaO, MgO, LOI, P2O5 and Fe2O3(total) compared with the least-altered BIF. Subsequent reactivation of these shear zones and circulation of hypogene fluids resulted in the leaching of existing hypogene carbonate minerals and the concentration of residual magnetite-rich bands. These Stage 3 magnetite-rich ore zones are depleted in SiO2 and enriched in K2O, CaO, MgO, P2O5 and Fe2O3(total) relative to the least-altered BIF. Proximal wall rock hypogene alteration zones in mafic igneous country rocks (up to 20 m from the BIF contact) are depleted in SiO2, CaO, Na2O, and K2O and are enriched in Fe2O3(total), MgO and P2O5 compared with distal zones. Recent supergene alteration affects all rocks within about 100 m below the present surface, disturbing hypogene mineral and the geochemical zonation patterns associated with

  7. Structural controls and evolution of gold-, silver-, and REE-bearing copper-cobalt ore deposits, Blackbird district, east-central Idaho: Epigenetic origins

    USGS Publications Warehouse

    Lund, K.; Tysdal, R.G.; Evans, K.V.; Kunk, M.J.; Pillers, R.M.

    2011-01-01

    Textural data at all scales indicate that the host sites for veins and the tectonic evolution of both host rocks and mineral deposits were kinematically linked to Late Cretaceous regional thrust faulting. Heat, fluids, and conduits for generation and circulation of fluids were part of the regional crustal thickening. The faulting also juxtaposed metaevaporite layers in the Mesoproterozoic Yellowjacket Formation over Blackbird district host rocks. We conclude that this facilitated chemical exchange between juxtaposed units resulting in leaching of critical elements (Cl, K, B, Na) from metaevaporites to produce brines, scavenging of metals (Co, Cu, etc) from rocks in the region, and, finally, concentrating metals in the lower-plate ramp structures. Although the ultimate source of the metals remains undetermined, the present Cu-Co ± Au (± Ag ± Ni ± REE) Blackbird ore deposits formed during Late Cretaceous compressional deformation.

  8. Spatial and temporal distribution of Cu-Au-Mo ore deposits along the western Tethyan convergent margin: a link with the 3D subduction dynamics

    NASA Astrophysics Data System (ADS)

    Menant, A.; Bertrand, G.; Loiselet, C.; Guillou-Frottier, L.; Jolivet, L.

    2012-12-01

    Emplacement conditions of mineralized systems in subduction and post-subduction environments and the sources of metals such as Cu, Mo and Au have been considered in the past. However, despite their importance in exploration strategies at the continental scale, interrelationships between distribution of ore systems and subduction dynamics are still partly unclear. Along the western Tethyan convergent margin, where Tertiary subduction history is well constrained, porphyry, epithermal and skarn ore deposits show a variable evolution of their spatial distribution. Using different and complementary database on European and Middle East ore deposits, three metallogenic episodes have been highlighted: (1) a late Cretaceous - Paleocene phase characterized by a copper mineralization within the Balkan chain and in the Kaçkar mountains (eastern Turkey), (2) an Eocene phase with a few copper ore deposits in eastern Turkey and small Caucasia and (3) an Oligocene - Neogene phase with a more southern distribution along the margin and mainly constituted by epithermal Au systems in the west (Carpathians, Rhodope, Aegean and western Turkey) and by porphyry copper deposits in the east (Zagros). These changes are suspected to be controlled by complex and evolving subduction dynamics. Using paleogeographic tools, it turned out that, in the eastern Mediterranean area, the late Cretaceous - Paleocene and Oligocene - Neogene metallogenic episodes are coeval with a significant decrease of the Africa - Eurasia convergence rate, from about 1.5 to 0.4 cm/yr. Indeed, compressional tectonics in the volcanic arc domain, associated with a high convergent rate, promote the storage of large volumes of metal-rich magma and the development of an extensive MASH (melting, assimilation, storage and homogenization) zone. When this convergence rate decreases, a stress relaxation occurs in the overriding crust, inducing the ascent of a sufficient flux of this fertile magma and allowing the formation of

  9. Use of sodium sulfide to restore aquifers subjected to in-situ leaching of uranium ore deposits

    SciTech Connect

    Deutsch, W.J.; Eary, L.E.; Martin, W.J.; McLaurine, S.B.

    1984-12-01

    Commonly used restoration techniques include ground water sweeping and recirculation of fresh water through the leached ore zone; however, such techniques introduce oxidizing waters into the ore zone. Consequently, redox-sensitive elements, such as uranium, arsenic, selenium, and molybdenum, may be difficult to restore to background levels because they continue to dissolve when these restoration techniques are used. To immobilize the redox-sensitive elements and restore tthe sediment. sediments as well as the ground water, it has been suggested that a reducing agent be circulated through the leached ore zone during restoration. We have conducted laboratory batch and flow-through column experiments to test the ability of sodium sulfide to enhance the restoration of sediment and solution typical of that found in a leached ore zone. Sodium sulfide effectively lowered the redox potential of the solution to the point that relatively insoluble minerals that contain the redox-sensitive elements should be stable. For some batch experiments, the uranium concentration of the solution decreased by more than three orders of magnitude, from 44 to 0.04 ppM. Although arsenic, selenium, and molybdenum were not present at contaminant levels in these solutions, we expect that, under the chemical conditions imposed by the sulfide, these three elements would also be immobilized because of the formation of insoluble sulfides or other sparingly soluble minerals. In the column experiments, we observed the formation and movement of a redox-interface, starting at the influent end of our columns. By the time ten pore volumes of the sulifide solution had flowed through the columns, the majority of the column had been altered from light gray in color to dark black, suggesting that sulfide minerals were forming throughout the sediment.

  10. SHRIMP U-Pb ages of xenotime and monazite from the Spar Lake red bed-associated Cu-Ag deposit, western Montana: Implications for ore genesis

    USGS Publications Warehouse

    Aleinikoff, John N.; Hayes, Timothy S.; Evans, Karl V.; Mazdab, Frank K.; Pillers, Renee M.; Fanning, C. Mark

    2012-01-01

    Xenotime occurs as epitaxial overgrowths on detrital zircons in the Mesoproterozoic Revett Formation (Belt Supergroup) at the Spar Lake red bed-associated Cu-Ag deposit, western Montana. The deposit formed during diagenesis of Revett strata, where oxidizing metal-bearing hydrothermal fluids encountered a reducing zone. Samples for geochronology were collected from several mineral zones. Xenotime overgrowths (1–30 μm wide) were found in polished thin sections from five ore and near-ore zones (chalcocite-chlorite, bornite-calcite, galena-calcite, chalcopyrite-ankerite, and pyrite-calcite), but not in more distant zones across the region. Thirty-two in situ SHRIMP U-Pb analyses on xenotime overgrowths yield a weighted average of 207Pb/206Pb ages of 1409 ± 8 Ma, interpreted as the time of mineralization. This age is about 40 to 60 m.y. after deposition of the Revett Formation. Six other xenotime overgrowths formed during a younger event at 1304 ± 19 Ma. Several isolated grains of xenotime have 207Pb/206Pb ages in the range of 1.67 to 1.51 Ga, and thus are considered detrital in origin. Trace element data can distinguish Spar Lake xenotimes of different origins. Based on in situ SHRIMP analysis, detrital xenotime has heavy rare earth elements-enriched patterns similar to those of igneous xenotime, whereas xenotime overgrowths of inferred hydrothermal origin have hump-shaped (i.e., middle rare earth elements-enriched) patterns. The two ages of hydrothermal xenotime can be distinguished by slightly different rare earth elements patterns. In addition, 1409 Ma xenotime overgrowths have higher Eu and Gd contents than the 1304 Ma overgrowths. Most xenotime overgrowths from the Spar Lake deposit have elevated As concentrations, further suggesting a genetic relationship between the xenotime formation and Cu-Ag mineralization.

  11. How two gravity-gradient inversion methods can be used to reveal different geologic features of ore deposit - A case study from the Quadrilátero Ferrífero (Brazil)

    NASA Astrophysics Data System (ADS)

    Carlos, Dionísio U.; Uieda, Leonardo; Barbosa, Valeria C. F.

    2016-07-01

    Airborne gravity gradiometry data have been recently used in mining surveys to map the 3D geometry of ore deposits. This task can be achieved by different gravity-gradient inversion methods, many of which use a voxel-based discretization of the Earth's subsurface. To produce a unique and stable solution, an inversion method introduces particular constraints. One constraining inversion introduces a depth-weighting function in the first-order Tikhonov regularization imposing a smoothing on the density-contrast distributions that are not restricted to near-surface regions. Another gravity-gradient inversion, the method of planting anomalous densities, imposes compactness and sharp boundaries on the density-contrast distributions. We used these two inversion methods to invert the airborne gravity-gradient data over the iron-ore deposit at the southern flank of the Gandarela syncline in Quadrilátero Ferrífero (Brazil). Because these methods differ from each other in the particular constraint used, the estimated 3D density-contrast distributions reveal different geologic features of ore deposit. The depth-weighting smoothing inversion reveals variable dip directions along the strike of the retrieved iron-ore body. The planting anomalous density inversion estimates a compact iron-ore mass with a single density contrast, which reveals a variable volume of the iron ore along its strike increasing towards the hinge zone of the Gandarela syncline which is the zone of maximum compression. The combination of the geologic features inferred from each estimate leads to a synergistic effect, revealing that the iron-ore deposit is strongly controlled by the Gandarela syncline.

  12. Chalcophile element (Ni, Cu, PGE, and Au) variations in the Tamarack magmatic sulfide deposit in the Midcontinent Rift System: implications for dynamic ore-forming processes

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2016-03-01

    The Tamarack magmatic sulfide deposit is hosted by the Tamarack Intrusive Complex (1105.6 ± 1.2 Ma) in the Midcontinent Rift System. The most important sulfide mineralization in the Complex occurs in the northern part, which consists of two separate intrusive units: an early funnel-shaped layered peridotite body containing relatively fine-grained olivine (referred to as the FGO Intrusion) at the top, and a late gabbro-troctolite-peridotite dike-like body containing relatively coarse-grained olivine (referred to as the CGO Intrusion) at the bottom. Disseminated, net-textured, and massive sulfides occur in the base of the FGO Intrusion as well as in the upper part of the CGO Intrusion. The widest part of the CGO Intrusion also hosts a large semi-massive (net-textured) sulfide ore body locally surrounded by disseminated sulfide mineralization. Small massive sulfide veins occur in the footwall of the FGO Intrusion and in the wall rocks of the CGO dike. The sulfide mineralization is predominantly composed of pyrrhotite, pentlandite, and chalcopyrite, plus minor magnetite. Pyrrhotite containing the highest Ni and Co contents occurs in the FGO disseminated sulfides and in the CGO semi-massive sulfide ores, respectively. The most important platinum-group minerals associated with the base metal sulfides are sperrylite (PtAs2), sudburyite (PdSb), and michenerite (PdBiTe). Nickel shows a strong positive correlation with S in all types of sulfide mineralization, and Cu shows a strong positive correlation with S in the disseminated sulfide mineralization. At a given S content, the concentrations of Pt, Pd, and Au in the CGO disseminated sulfides are significantly higher than those in the FGO disseminated sulfides. The semi-massive sulfide ores are characterized by significantly higher IPGE (Ir, Os, Ru, and Rh) concentrations than most of the massive sulfide ores. With few exceptions, all of the various textural types of sulfide mineralization collectively show a good positive

  13. Chalcophile element (Ni, Cu, PGE, and Au) variations in the Tamarack magmatic sulfide deposit in the Midcontinent Rift System: implications for dynamic ore-forming processes

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2016-10-01

    The Tamarack magmatic sulfide deposit is hosted by the Tamarack Intrusive Complex (1105.6 ± 1.2 Ma) in the Midcontinent Rift System. The most important sulfide mineralization in the Complex occurs in the northern part, which consists of two separate intrusive units: an early funnel-shaped layered peridotite body containing relatively fine-grained olivine (referred to as the FGO Intrusion) at the top, and a late gabbro-troctolite-peridotite dike-like body containing relatively coarse-grained olivine (referred to as the CGO Intrusion) at the bottom. Disseminated, net-textured, and massive sulfides occur in the base of the FGO Intrusion as well as in the upper part of the CGO Intrusion. The widest part of the CGO Intrusion also hosts a large semi-massive (net-textured) sulfide ore body locally surrounded by disseminated sulfide mineralization. Small massive sulfide veins occur in the footwall of the FGO Intrusion and in the wall rocks of the CGO dike. The sulfide mineralization is predominantly composed of pyrrhotite, pentlandite, and chalcopyrite, plus minor magnetite. Pyrrhotite containing the highest Ni and Co contents occurs in the FGO disseminated sulfides and in the CGO semi-massive sulfide ores, respectively. The most important platinum-group minerals associated with the base metal sulfides are sperrylite (PtAs2), sudburyite (PdSb), and michenerite (PdBiTe). Nickel shows a strong positive correlation with S in all types of sulfide mineralization, and Cu shows a strong positive correlation with S in the disseminated sulfide mineralization. At a given S content, the concentrations of Pt, Pd, and Au in the CGO disseminated sulfides are significantly higher than those in the FGO disseminated sulfides. The semi-massive sulfide ores are characterized by significantly higher IPGE (Ir, Os, Ru, and Rh) concentrations than most of the massive sulfide ores. With few exceptions, all of the various textural types of sulfide mineralization collectively show a good positive

  14. Lead isotope study of Zn-Pb ore deposits associated with the Basque-Cantabrian basin and Paleozoic basement, Northern Spain

    NASA Astrophysics Data System (ADS)

    Velasco, F.; Pesquera, A.; Herrero, J. M.

    1996-01-01

    A total of forty-three galena samples from syngenetic and epigenetic Pb-Zn mineralizations emplaced in the Lower Cretaceous Basque-Cantabrian basin and Paleozoic basement of the Cinco Villas massif in the western Pyrenees, have been analyzed for Pb-isotopic composition. Galena from sedex mineralizations hosted in Carboniferous clastic rocks in the Cinco Villas massif display an homogeneous lead isotopic signature (206Pb/2044Pb ≈ 18.43, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.69) suggesting a single lead reservoir. These values are slightly more radiogenic than lead from other European Hercynian deposits, possibly reflecting the influence of a more evolved upper crustal source. Underlying Paleozoic sediments are proposed as lead source for the Cinco Villas massif ores. Analyses from twenty-six galena samples from the four strata-bound ore districts hosted in Mesozoic rocks reveal the existence of two populations regarding their lead isotopic composition. Galena from the western Santander districts (e.g., Reocin) is characterized by more radiogenic isotope values (206Pb/204Pb ≈ 18.74, 207Pb/204Pb ≈ 15.67, 208Pb/ 204Pb ≈ 38.73) than those from the central and eastern districts (Troya-Legorreta, Central and Western Vizcaya, 206Pb/204Pb ≈ 18.59, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.73). In all districts, the most likely source for these mineralizations was the thick sequence of Lower Cretaceous clastic sediments. The existence of two separate lead isotopic populations could be the result of regional difference in the composition of the basement rocks and the clastic sediments derived of it or different evolution histories. In both sub-basins, isotopic ratios indicate an increase in crustal influence as the age of the ores decreases.

  15. Sulfur isotope and trace element data from ore sulfides in the Noranda district (Abitibi, Canada): implications for volcanogenic massive sulfide deposit genesis

    NASA Astrophysics Data System (ADS)

    Sharman, Elizabeth R.; Taylor, Bruce E.; Minarik, William G.; Dubé, Benoît; Wing, Boswell A.

    2015-06-01

    We examine models for volcanogenic massive sulfide (VMS) mineralization in the ~2.7-Ga Noranda camp, Abitibi subprovince, Superior Province, Canada, using a combination of multiple sulfur isotope and trace element data from ore sulfide minerals. The Noranda camp is a well-preserved, VMS deposit-rich area that is thought to represent a collapsed volcanic caldera. Due to its economic value, the camp has been studied extensively, providing a robust geological framework within which to assess the new data presented in this study. We explore previously proposed controls on mineralization within the Noranda camp and, in particular, the exceptional Au-rich Horne and Quemont deposits. We present multiple sulfur isotope and trace element compositional data for sulfide separates representing 25 different VMS deposits and "showings" within the Noranda camp. Multiple sulfur isotope data for this study have δ34SV-CDT values of between -1.9 and +2.5 ‰, and Δ33SV-CDT values of between -0.59 and -0.03 ‰. We interpret the negative Δ33S values to be due to a contribution of sulfur that originated as seawater sulfate to form the ore sulfides of the Noranda camp VMS deposits. The contribution of seawater sulfate increased with the collapse and subsequent evolution of the Noranda caldera, an inference supported by select trace and major element analyses. In particular, higher concentrations of Se occur in samples with Δ33S values closer to 0 ‰, as well as lower Fe/Zn ratios in sphalerite, suggesting lower pressures and temperatures of formation. We also report a relationship between average Au grade and Δ33S values within Au-rich VMS deposits of the Noranda camp, whereby higher gold grades are associated with near-zero Δ33S values. From this, we infer a dominance of igneous sulfur in the gold-rich deposits, either leached from the volcanic pile and/or directly degassed from an associated intrusion.

  16. Correlation between compositions of ore and host rocks in volcanogenic massive sulfide deposits of the Southern Urals

    NASA Astrophysics Data System (ADS)

    Seravkin, I. B.

    2013-05-01

    The geology and typification of volcanogenic massive sulfide (VMS) deposits of the Southern Urals are considered. The mineralogical-geochemical types of these deposits correlate with the composition of the underlying igneous rocks: Ni-Co-Cu deposits correlatedwith serpentinites (Ivanovka type); (Co)-Cu deposits, with basalts (Dombarovka type); Cu-Zn deposits, with basalt-rhyolite and basalt-andesite-rhyolite complexes (Ural type); and Au-Ba-Pb-Zn-Cu deposits, with basalt-andesite-rhyolite complexes with predominance of andesitic and felsic volcanics (Baimak type). The Ural-type deposits are subdivided into three subtypes: I, underlain by basalts (Zn-Cu deposits); II, hosted in felsic volcanic rocks of bimodal complexes (Cu-Zn deposits); and III, hosted in felsic volcanic rocks of continuously differentiated complexes (Zn-Cu deposits with Ba, Pb, and As). The above types and subtypes bearing local names are compared with global types of VMS deposits (MAR, Cyprus, Noranda, and Kuroko), to which they are close but not identical.

  17. Significance of the precambrian basement and late Cretaceous thrust nappes on the location of tertiary ore deposits in the Oquirrh Mountains, Utah

    USGS Publications Warehouse

    Tooker, Edwin W.

    2005-01-01

    The Oquirrh Mountains are located in north central Utah, in the easternmost part of the Basin and Range physiographic province, immediately south of the Great Salt Lake. The range consists of a northerly trending alignment of peaks 56 km long. Tooele and Rush Valleys flank the Oquirrh Mountains on the western side and Salt Lake and Cedar Valleys lie on the eastern side. The world class Bingham mine in the central part of the range hosts disseminated copper-bearing porphyry, skarn, base-and precious-metal vein and replacement ore deposits. The district includes the outlying Barneys Canyon disseminated-gold deposits. Disseminated gold in the Mercur mining district in the southern part of the range has become exhausted. The Ophir and Stockton base- and precious-metal mining districts in the range north of Mercur also are inactive. A geologic map of the range (Tooker and Roberts, 1998), available at a scale of 1:50,000, is a summation of U.S. Geological Survey (USGS) studies. Information about the range and its mining areas is scattered. This report summarizes map locations, new stratigraphic and structural data, and reexamined data from an extensive published record. Unresolved controversial geological interpretations are considered, and, for the first time, the complete geological evidence provides a consistent regional basis for the location of the ore deposits in the range. The geological setting and the siting of mineral deposits in the Oquirrh Mountains began with the formation of a Precambrian craton. Exposures of folded Proterozoic basement rocks of the craton, in the Wasatch Mountains east of Salt Lake City, were accreted and folded onto an Archean crystalline rock terrane. The accretion suture lies along the north flank of the Uinta Mountains. The western part of the accreted block was offset to northern Utah along a north-trending fault lying approximately along the Wasatch Front (Nelson and others, 2002), thereby creating a prominant basement barrier or

  18. Geological, geochronological, and mineralogical constraints on the genesis of the Chengchao skarn Fe deposit, Edong ore district, Middle-Lower Yangtze River Valley metallogenic belt, eastern China

    NASA Astrophysics Data System (ADS)

    Yao, Lei; Xie, Guiqing; Mao, Jingwen; Lü, Zhicheng; Zhao, Caisheng; Zheng, Xianwei; Ding, Ning

    2015-04-01

    The Edong ore district is located within the westernmost Middle-Lower Yangtze River Valley metallogenic belt (MLYRB), and hosts the largest concentration of skarn Fe deposits in China, although the origin of these deposits remains controversial. The Chengchao deposit is the largest skarn Fe deposit so far discovered within the MLYRB, and provides a good opportunity to address the debate surrounding the origin of these skarn Fe deposits. Here, we present geological, geochronological, and mineralogical data from the Chengchao skarn deposit and associated intrusions, and discuss the relationships between granitoids and mineralization in the Chengchao deposit. The NW-SE-striking orebodies in the study area have porphyritic quartz monzonite and/or granite footwalls, and Triassic marble or diorite hangingwalls, indicating a spatial relationship between these intrusions and Fe mineralization. Zircon U-Pb data from the granite, porphyritic quartz monzonite, diorite, and porphyritic diabase dike within the deposit show ages of 129 ± 1, 128 ± 1, 140 ± 1, and 126 ± 1 Ma, respectively. These ages and the previously reported ages on the timing of mineralization suggest that the porphyritic quartz monzonite and granite are coeval with the formation of the skarn Fe deposit. Our data confirm that the granitic rocks are temporally associated with Fe mineralization. The prograde substage of skarn development is characterized by two stages of andradite (Adr98-38Grs61-2Prp2-0Sps1-0Alm1-0) and diopside (Di95-61Hd37-5Jo3-0), including an early stage of garnet and pyroxene formation that is genetically associated with the mineralization. The early stage garnets are more andradite-rich (Adr98-50Grs49-2Prp1-0Sps1-0Alm0) than the late veinlet garnets characterized by intermediate grandite compositions (Adr67-37Grs61-31Prp2-0Sps1-0Alm1-0). The early stage pyroxenes (Di95-74Hd26-5Jo1-0) are compositionally distinct from the late stage pyroxenes (Di84-61Hd37-16Jo3-0). Compositional

  19. Multiphase origin of the Cu Co ore deposits in the western part of the Lufilian fold-and-thrust belt, Katanga (Democratic Republic of Congo)

    NASA Astrophysics Data System (ADS)

    Dewaele, S.; Muchez, Ph.; Vets, J.; Fernandez-Alonzo, M.; Tack, L.

    2006-12-01

    A multiphase origin of the Cu-Co ores in the western part of the Lufilian fold-and-thrust belt in Central Africa is proposed based on literature, satellite image interpretations and petrographic and fluid inclusion analyses on samples from the stratiform mineralization of Kamoto and Musonoi (DR Congo). The various mineral occurrences in the Katanga Copperbelt can be classified in distinct categories: stratiform, supergene enrichment and vein-type. The stratiform mineralization form the largest group and can be found mainly in Lower Roan (R-2) rocks, which can be identified as ridges on satellite imagery. Ore deposits outside the R-2 occur along lineaments and result often from supergene enrichment. The main phase of the stratiform mineralization in the Katanga Copperbelt occurred during diagenesis preceding the Lufilian orogeny. Petrographic observation identified various mineralizing phases, which played a role in the formation of these stratiform mineralization. Mineralization started during early diagenesis, but mainly occurred during further burial. After the formation of early diagenetic pyrite, the circulation of diagenetic Cu-Co-rich fluids resulted in the formation of the main mineralization. Preliminary microthermometric investigation of primary inclusions in authigenic quartz, associated with the main stage of stratiform mineralization, indicates that an H 2O-NaCl fluid with a minimum temperature between 80 and 195 °C and a salinity between 8.4 and 18.4 eq. wt% NaCl circulated during the main phase of mineralization. Numerous faults and fractures formed during the Lufilian orogeny cut the stratiform mineralization. They are, however, at Kamoto and Musonoi only associated with minor sulphides. Supergene alteration along faults and fractures resulted in an enrichment of the mineralization, with the formation of secondary Cu-oxides, -carbonates and -silicates. The importance of the interaction of various processes for the formation of economic Cu-Co ore

  20. Lead-isotopic compositions of diverse igneous rocks and ore deposits from southwestern New Mexico and their implications for early Proterozoic crustal evolution in the western United States.

    USGS Publications Warehouse

    Stacey, J.S.; Hedlund, D.C.

    1983-01-01

    Basement rocks in this area are 1750 m.y. old and extend northward through Colorado to Utah. Galena data show that the fraction of older sialic lead in these rocks increases toward the the Archaean craton in Wyoming. The crust apparently developed southward from Wyoming in stages at 2400 m.y. ago or before, 2100 m.y. ago and 1750 m.y. ago. The Laramide alkali to calc-alkaline rocks and their associated porphyry Cu and massive replacement deposits have similar 206Pb/204Pb ratios and are the least radiogenic in the region; their 206Pb/204Pb ratios are all 18.0. Pb isotopes in this region offer some criteria for prospecting purposes. The 206Pb/204Pb values for the larger ore deposits related to Laramide activity are all <18.0, particularly for the larger ones. Within the mid- Tertiary group, the same criteria apply - i.e. the largest deposits have the lowest 206Pb/204Pb ratios. -L.C.H.

  1. Rubidium-strontium dating of ore deposits hosted by Rb-rich rocks, using calcite and other common Sr-bearing minerals

    SciTech Connect

    Ruiz, J.; Jones, L.M.; Kelly, W.C.

    1984-05-01

    The authors have tested a Rb-Sr technique that permits ore deposits to be dated using common gangue minerals such as calcite and fluorite. The only conditions the deposit must meet are that (1) it have minerals with a low Rb/Sr ratio and (2) it be enclosed by wall rock with a high Rb/Sr ratio. Because hydrothermal minerals acquire a strontium-isotope composition that is usually similar to that of the wall rock, minerals with low Rb/Sr ratio should record and retain the isotopic composition that the wall rock had at the time of mineralization. The difference between that ratio and that of the wall rock at present is a function of time and the Rb/Sr composition of the wall rock. The technique was tested fusing fluorite and calcite from three deposits ranging in age from Tertiary to Precambrian. In all cases the age determined here closely resembles that obtained by conventional K-Ar and Rb-Sr dating methods. The precision, however, can be poor and depends chiefly on the strontium-isotope heterogeneity of the wall rock and its Rb/Sr enrichment. 36 references, 1 figure, 1 table.

  2. How metallic is the binding state of indium hosted by excess-metal chalcogenides in ore deposits?

    NASA Astrophysics Data System (ADS)

    Ondina Figueiredo, Maria; Pena Silva, Teresa; Oliveira, Daniel; Rosa, Diogo

    2010-05-01

    Discovered in 1863, indium is nowadays a strategic scarce metal used both in classical technologic fields (like low melting-temperature alloys and solders) and in innovative nano-technologies to produce "high-tech devices" by means of new materials, namely liquid crystal displays (LCDs), organic light emitting diodes (OLEDs) and the recently introduced transparent flexible thin-films manufactured with ionic amorphous oxide semiconductors (IAOS). Indium is a typical chalcophile element, seldom forming specific minerals and occurring mainly dispersed within polymetallic sulphides, particularly with excess metal ions [1]. The average content of indium in the Earth's crust is very low but a further increase in its demand is still expected in the next years, thus focusing a special interest in uncovering new exploitation sites through promising polymetallic sulphide ores - e.g., the Iberian Pyrite Belt (IPB) [2] - and in improving recycling technologies. Indium recovery stands mostly on zinc extraction from sphalerite, the natural cubic sulphide which is the prototype of so-called "tetrahedral sulphides" where metal ions fill half of the available tetrahedral sites within the cubic closest packing of sulphur anions where the double of unfilled interstices are available for further in-filling. It is worth remarking that such packing array is particularly suitable for accommodating polymetallic cations by filling closely located interstitial sites [3] as happens in excess-metal tetrahedral sulphides - e.g. bornite, ideally Cu5FeS4, recognized as an In-carrying mineral [4]. Studying the tendency towards In-In interactions able of leading to the formation of polycations would efficiently contribute to understand indium crystal chemistry and the metal binding state in natural chalcogenides. Accordingly, an X-ray absorption near-edge spectroscopy (XANES) study at In L3-edge was undertaken using the instrumental set-up of ID21 beamline at the ESRF (European Synchrotron

  3. Scheelite geochemical signatures by LA-ICP-MS and potential for rare earth elements from Hutti Gold Mines and fingerprinting ore deposits

    NASA Astrophysics Data System (ADS)

    Raju, P. V. S.; Hart, Craig J. R.; Sangurmath, P.

    2016-02-01

    Scheelite (CaWO4), with gold and REE enrichments, is found in appreciable concentrations in the world class Hutti Gold deposit, Eastern Dharwar Craton (EDC), India. We used in situ Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) to determine the rare earth elements in scheelite and utilize results to fingerprint the extensions/continuity of auriferous ore shoots/lodes/reefs. The Hutti Gold deposit is briefly compared to southern African gold deposits and corroborates in terms of geochemistry, structural, chemical alterations and REE contents in scheelite etc… The scheelite samples from Hutti are enriched in light rare earth elements (LREE) up to 11 ppm and depleted in heavy rare earth elements(HREE) up to 6.50 ppm with positive to negative europium anomaly. The total REE (∑ REE + Y) of the scheelite samples is up to 35 ppm. The ratio of LREE/HREE values is 1.80. The results for the REEs indicate: (1) considerable differences in the ΣREEs amongst the sample suite (2) most samples are dominated by a single chondrite-normalized (CN) pattern, but rarely a second pattern is present; 3) although the type of CN REE patterns vary (e.g., convex MREE, LREE enrichment), there is a similarity among deposit types; and 4) both positive and negative 'Eu' anomalies are observed; 5) positive correlations between MREE and HREE suggesting a strong influence of magmatic fluids. These initial results suggest that the minor and trace-element chemistry of scheelite may offer the potential to discriminate and identify deposit types based on its geochemical fingerprinting.

  4. Field Vectors to Metamorphosed Ores: A Prelude to Finding Currently Concealed Volcano-Plutonic Arc Settings and Their Mineral Deposits in The Grenville Province

    NASA Astrophysics Data System (ADS)

    Corriveau, L.; Bonnet, A.; van Breemen, O.

    2004-05-01

    Recent mineral deposits synthesis highlights the largely barren nature of the high-grade metamorphic terrains of the Canadian Shield in terms of large mining camps. No where is the gap most startling than in the Grenville Province even though a lot of its Paleo- to Mesoproterozoic crust consists of magmatic arcs renown worldwide to host IOCG, VHMS and Porphyry Cu deposits. All these deposit types have significant alteration halos that can serve as vectors to ore. The use of such vectors forced a complete reinterpretation of the nature of the La Romaine domain in the eastern Grenville Province. Mapped in the 70's as being a metasedimentary basin with >500 km2 of meta-arkose and minor pelite, quartzite, conglomerate and marble, the domain is herein reassessed as a major 1.5 Ga Pinwarian continental magmatic arc fertile in Cu-sulphides and Fe-oxides mineralizing systems. The original markers used to prognosticate a sedimentary origin can now be demonstrated to be a series of rhyolitic to dacitic lapillistone, sericitized tuff with Al nodules and veins, Al gneiss locally with lapilli textures, garnetite, ironstones and calc-silicate rocks. The distribution, paragenesis and mode of the Al-, Fe- and Ca-rich units significantly depart from those of normal metasediments but are very diagnostic of metamorphosed hydrothermal alteration zones and meta-exhalites. Mapping alteration vectors provided clues to search for and find the volcanic rocks concealed among the composite granitic gneiss, the zones of hydrothermal leaching (e.g., sericitic, argillic and advanced argillic alterations) and discharge, the cap rocks, and the Cu mineralization. Spatial and stratigraphic relationships provided a means to compare their settings with ore deposit models. Roof pendants of Ba-rich meta-exhalite in surrounding 1.5 Ga granitic plutons and intrusion of 1495 Ma Qtz-Kfs porphyry across hydrothermally altered 1500 Ma tuffs attest to coeval hydrothermal activity and sub-volcanic plutons. The

  5. Geochemical and Nd isotopic constraints on provenance and depositional setting of the Shihuiding Formation in the Shilu Fe-Co-Cu ore district, Hainan Province, South China

    NASA Astrophysics Data System (ADS)

    Yu, Liangliang; Zou, Shaohao; Cai, Jianxin; Xu, Deru; Zou, Fenghui; Wang, Zhilin; Wu, Chuanjun; Liu, Meng

    2016-04-01

    The Shihuiding Formation, a subordinate succession hosting the Fe-Co-Cu ores, is a suite of Neoproterozoic terrigenous clastic rocks occurring in the Shilu Fe-Co-Cu ore district of the Hainan Island, South China. Integrated petrographical, geochemical, and Nd isotopic analyses have been carried out on 23 sandstone specimens of the Shihuiding Formation in order to understand their provenance and the tectonic setting of their deposition. The samples can be divided into two groups, quartzose sandstones (13 samples) and ferruginous sandstones (10 samples). The ferruginous sandstones have average SiO2 and Fetotal contents of 77.23 wt.% and 18.09 wt.%, respectively, and this contrasts with the higher average SiO2 (94.04 wt.%) and lower Fetotal (2.67 wt.%) contents of the quartzose sandstones. The bivariant Th/Sc and Zr/Sc ratios indicate a predominantly recycled sedimentary provenance, and the low to medium degrees of weathering are commonly indicated by an average chemical index of maturity (CIM) of 81 and an average chemical index of alteration (CIA) of 68. The Shihuiding Formation sandstones have REE contents of 21-249 ppm, with LREE/HREE = 9.18 and δEu = 0.67. The εNd (970 Ma) values of -5.7 to -3.4, and model (TDM) ages of 2099-1773 Ma are compatible with a source mainly from the Paleo- to Mesoproterozoic Baoban Group, a suite of metamorphosed sedimentary rocks intruded by ca. 1450 Ma granites. Quantitative provenance modeling indicates that the Shihuiding Formation sandstones are best modeled with a mixture of 29% plagioclase-amphibole gneiss (29 P), 38% quartz-muscovite schist (38 Q), and 33% granite (33 G) detritus. Mixing the εNd values of the sandstones, calculated at 970 Ma, indicates that the sediment received 22-47% (average 34%) of its detritus from the Baoban Group quartz-muscovite schists. Components from hydrothermal fluids may also have been involved during deposition of the Shihuiding Formation sandstones, as revealed by a bivariant Al/(Al + Fe + Mn

  6. Gas-exchange chamber analysis of elemental mercury deposition/emission to alluvium, ore, and mine tailings.

    PubMed

    Miller, Matthieu B; Gustin, Mae Sexauer

    2015-07-01

    Deposition of mercury (Hg) from the atmosphere is an important source of this contaminant to terrestrial ecosystems. Once deposited, all forms of Hg can be retained or emitted back to the atmosphere. Distinguishing between volatilization of geogenic or indigenous Hg and that deposited from the atmosphere is difficult. Field flux measurements in the general area of two industrial scale gold mining operations, showed local deposition of Hg emitted from point and nonpoint sources, and subsequent re-emission. The work presented in this paper investigated deposition/emission of elemental Hg to and from alluvium and two mine materials before, during, and after exposure to high air concentrations, for both wet and dry conditions, using a laboratory gas exchange chamber and a Hg permeation source. In general, results showed a range in mean elemental Hg deposition velocities ranging from 0.13 to 0.46 cm s(-1) that varied with material. A significant influence of atmospheric ozone (O3) on flux was observed that depended on the material and whether wet or dry. A synergistic relationship existed between O3 and light promoting Hg flux, and flux was also influenced by material grain size, chemistry, and primary mineralogy.

  7. Application of low-temperature thermochronology to hydrothermal ore deposits: Formation, preservation and exhumation of epithermal gold systems from the Eastern Rhodopes, Bulgaria

    NASA Astrophysics Data System (ADS)

    Márton, István; Moritz, Robert; Spikings, Richard

    2010-03-01

    New low-temperature thermochronological data have been used to quantify the protracted, Eocene-Miocene cooling histories of upper and lower plate rocks of the Kesebir-Kardamos extensional dome, Eastern Rhodopes, Bulgaria. 40Ar/ 39Ar and apatite fission-track data reveal that the lower plate has experienced continuous cooling and exhumation, since the Late Eocene. Muscovite 40Ar/ 39Ar plateau ages of 36.90 ± 0.16 Ma and 37.28 ± 0.19 Ma (2 σ) from metamorphic rocks of the footwall reveal the approximate time span during which they cooled below ˜ 350 °C during exhumation caused by detachment faulting. The sedimentary rock-hosted gold mineralization, which represents a thermal event at ˜ 250-220 °C, developed during the early stage of basin formation between 34.71 ± 0.16 Ma and 35.36 ± 0.21 Ma (adularia 40Ar/ 39Ar plateau ages; 2 σ). The termination of hydrothermal mineral deposition at Ada Tepe occurred contemporaneously with the earliest phase of calc-alkaline type magmatism at Iran Tepe (33.97 ± 0.36 Ma to 34.62 ± 0.46 Ma, hornblende and biotite 40Ar/ 39Ar plateau ages, 2 σ). Thermal history modelling of apatite fission-track data shows that the lower plate rocks cooled through ˜ 120 °C at ˜ 18.3 ± 1.9 Ma (1 σ). A time-temperature model obtained from zircon and apatite fission-track data from the upper plate reveals that it was being buried during the late Eocene. At ˜ 33-30 Ma, a dramatic change of the time-temperature path was caused by the initiation of horst-graben structures, resulting in rapid exhumation of the upper plate. Our new thermochronological data reveal many aspects of the mechanisms of formation of sedimentary rock-hosted gold deposits. The heat accumulated during sedimentary burial of the upper plate is a plausible heat source to drive hydrothermal fluid circulation and ore formation. The development of large half-graben basins in the hanging walls of detachment faults, accompanied by a favourable climate, may have created a

  8. Early Permian stage of formation of gold-ore deposits of northeastern Transbaikalia: Isotope-geochronological (Rb-Sr and 39Ar-40Ar) data for the Uryakh ore field

    NASA Astrophysics Data System (ADS)

    Chugaev, A. V.; Nosova, A. A.; Abramov, S. S.; Chernyshev, I. V.; Bortnikov, N. S.; Larionova, Yu. O.; Goltsman, Yu. V.; Moralev, G. V.; Volfson, A. A.

    2015-08-01

    This work presents the first results of geochronological study of metasomatic rocks accompanying gold-bearing quartz veins of the Uryakh ore field (UOF). Based on the Rb-Sr and 39Ar-40Ar geochronological data, it is shown that hydrothermal metasomatic processes in the ore field occurred about 280 Ma ago (Early Permian) and they are correlated with the terminal phases of formation of the Angara-Vitim batholith.

  9. Lead-isotopic, sulphur-isotopic, and trace-element studies of galena from the Silesian-Cracow Zn-Pb ores, polymetallic veins from the Gory Swietokrzyskie MTS, and the Myszkow porphyry copper deposit, Poland

    USGS Publications Warehouse

    Church, S.E.; Vaughn, R.B.; Gent, C.A.; Hopkins, R.T.

    1996-01-01

    Lead-isotopic data on galena samples collected from a paragenetically constrained suite of samples from the Silesian-Cracow ore district show no regional or paragenetically controlled lead-isotopic trends within the analytical reproducibility of the measurements. Furthermore, the new lead-isotopic data agree with previously reported lead-isotopic results (R. E. Zartman et al., 1979). Sulfur-isotopic analyses of ores from the Silesian-Cracow district as well as from vein ore from the Gory Swietokrzyskie Mts. and the Myszkow porphyry copper deposit, when coupled with trace-element data from the galena samples, clearly discriminate different hydrothermal ore-forming events. Lead-isotopic data from the Permian and Miocene evaporite deposits in Poland indicate that neither of these evaporite deposits were a source of metals for the Silesian-Cracow district ores. Furthermore, lead-isotopic data from these evaporite deposits and the shale residues from the Miocene halite samples indicate that the crustal evolution of lead in the central and western European platform in southern Poland followed normal crustal lead-isotopic growth, and that the isotopic composition of crustal lead had progressed beyond the lead-isotopic composition of lead in the Silesian-Cracow ores by Permian time. Thus, Mesozoic and Tertiary sedimentary flysch rocks can be eliminated as viable source rocks for the metals in the Silesian-Cracow Mississippi Valley-type (MVT) deposits. The uniformity of the isotopic composition of lead in the Silesian-Cracow ores, when coupled with the geologic evidence that mineralization must post-date Late Jurassic faulting (E. Gorecka, 1991), constrains the geochemical nature of the source region. The source of the metals is probably a well-mixed, multi-cycle molasse sequence of sedimentary rocks that contains little if any Precambrian metamorphic or granitic clasts (S. E. Church, R. B. Vaughn, 1992). If ore deposition was post Late Jurassic (about 150 m. y.) or later

  10. The genesis of ores

    SciTech Connect

    Brimhall, G. )

    1991-05-01

    Human history and technology have been shaped by metals. How did they become concentrated in minable deposits located so conveniently near the earth's surface The author explains the mechanisms of fluid transport-by magma, water and even air and wind-responsible for the chemical and physical interactions that created bodies of metallic ores throughout geologic history. From their formation to their modification at the surface of the earth, ore deposits are geologically transitory and reflect dynamic processes within the earth as well as atmospheric and climatic influences on hydrologic systems. As highly reactive supracrustal systems, they then serve as geochemical sensors providing a powerful record and set of tracer elements for deducing the history, transport paths and forces operative in the crust.

  11. Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

    USGS Publications Warehouse

    Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.

    2004-01-01

    The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (<27 ppm) and Tl (<37 ppm). Late tan sphalerite has distinctly lower Fe (< 0.9 wt %) and higher Tl (up to 355 ppm), Mn (up to 177 ppm), and Ge (426 ppm), relative to earlier sphalerite. Wide ranges in concentrations of Ag, Cu, Pb, and Sb characterize all sphalerite types, particularly yellow-brown sphalerite and red-brown sphalerite, and most likely reflect submicroscopic inclusions of galena, chalcopyrite and/or tetrahedrite in the sphalerite. In situ ion microprobe sulfur isotope analyses show a progression from extremely low ??34S values for stage 1 (as low as -37.20???) to much higher values for yellow-brown sphalerite (mean of 3.3???; n = 30) and red-brown sphalerite (mean of 3.4; n = 20). Late tan sphalerite is isotopically light (-16.4 to -27.2???). The textural, chem ical, and isotopic data indicate the following paragenesis: (1) deposition of early brown sphalerite with abundant barite, minor pyrite, and trace galena immediately beneath the sea floor in unconsolidated mud; (2) deposition

  12. Geographical Coincidence of High Heat Flow, High Seismicity, and Upwelling, with Hydrocarbon Deposits, Phosphorites, Evaporites, and Uranium Ores

    PubMed Central

    Libby, L. M.; Libby, W. F.

    1974-01-01

    Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, high heat flux, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10-4 of the total of buried biogenic carbon. Images PMID:16592185

  13. Geographical coincidence of high heat flow, high seismicity, and upwelling, with hydrocarbon deposits, phosphorites, evaporites, and uranium ores.

    PubMed

    Libby, L M; Libby, W F

    1974-10-01

    Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, high heat flux, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10(-4) of the total of buried biogenic carbon. PMID:16592185

  14. Geographical coincidence of high heat flow, high seismicity, and upwelling, with hydrocarbon deposits, phosphorites, evaporites, and uranium ores.

    PubMed

    Libby, L M; Libby, W F

    1974-10-01

    Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, high heat flux, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10(-4) of the total of buried biogenic carbon.

  15. Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Structural controls on hydrothermal alteration and ore mineralization

    USGS Publications Warehouse

    Berger, B.R.; Henley, R.W.

    2011-01-01

    High-sulfidation copper-gold lode deposits such as Chinkuashih, Taiwan, Lepanto, Philippines, and Goldfield, Nevada, formed within 1500. m of the paleosurface in volcanic terranes. All underwent an early stage of extensive advanced argillic silica-alunite alteration followed by an abrupt change to spatially much more restricted stages of fracture-controlled sulfide-sulfosalt mineral assemblages and gold-silver mineralization. The alteration as well as ore mineralization stages of these deposits were controlled by the dynamics and history of syn-hydrothermal faulting. At the Sulfate Stage, aggressive advanced argillic alteration and silicification were consequent on the in situ formation of acidic condensate from magmatic vapor as it expanded through secondary fracture networks alongside active faults. The reduction of permeability at this stage due to alteration decreased fluid flow to the surface, and progressively developed a barrier between magmatic-vapor expansion constrained by the active faults and peripheral hydrothermal activity dominated by hot-water flow. In conjunction with the increased rock strength resulting from alteration, subsequent fault-slip inversion in response to an increase in compressional stress generated new, highly permeable fractures localized by the embrittled, altered rock. The new fractures focused magmatic-vapor expansion with much lower heat loss so that condensation occurred. Sulfide Stage sulfosalt, sulfide, and gold-silver deposition then resulted from destabilization of vapor phase metal species due to vapor decompression through the new fracture array. The switch from sulfate to sulfide assemblages is, therefore, a logical consequence of changes in structural permeability due to the coupling of alteration and fracture dynamics rather than to changes in the chemistry of the fluid phase at its magmatic source. ?? 2010.

  16. Origin of the ore-forming fluids of the Tongchang porphyry Cu-Mo deposit in the Jinshajiang-Red River alkaline igneous belt, SW China: Constraints from He, Ar and S isotopes

    NASA Astrophysics Data System (ADS)

    Xu, Leiluo; Bi, Xianwu; Hu, Ruizhong; Tang, Yongyong; Jiang, Guohao; Qi, Youqiang

    2014-01-01

    The Jinshajiang-Red River alkaline igneous belt with abundant Cu-Mo-Au mineralization, in the eastern Indian-Asian collision zone, is an important Cenozoic magmatic belt formed under an intra-continental strike-slip system in southwestern (SW) China. The Tongchang deposit is a representative porphyry Cu-Mo deposit in southern segment of the Jinshajiang-Red River alkaline igneous belt, with 8621 t Cu @ 1.24 wt.% and 17,060 t Mo @ 0.218 wt.%. In this study, He, Ar and S isotopic compositions of the Tongchang deposit were determined. He and Ar isotopic compositions suggest that the ore-forming fluids, with 3He/4He ratios varying from 0.17 to 1.50 Ra and 40Ar/36Ar ratios from 299.1 to 347.3 for the deposit, are a mixture between a crust-derived fluid (MASW) with near atmospheric Ar and crustal He, and a mantle-derived fluid. However, the δ34S values of the hydrothermal pyrite samples ranging from 1.0‰ to 1.5‰ with an average of 1.2‰, indicate that the sulfur in the ore-forming fluids of the Tongchang deposit was primarily derived from the magma or indirectly mantle-derived without assimilation of crustal sulfur. In combination with previously published He and Ar isotopic data of the Yulong and Machangqing deposits in northern and central segments of the Jinshajiang-Red River alkaline igneous belt, respectively, the ore-forming fluids of the Yulong and Machangqing deposits are obviously richer in 3He and 40Ar, and poorer in 36Ar in comparison with the Tongchang deposit, implying that more mantle-derived fluids were involved in the ore-forming fluids of the Yulong and Machangqing deposits than those for the Tongchang deposit. This might be one of the most important factors producing larger scales of mineralization in the Yulong and Machangqing deposits than the Tongchang deposit.

  17. Three mechanisms of ore re-mobilisation during amphibolite facies metamorphism at the Montauban Zn-Pb-Au-Ag deposit

    NASA Astrophysics Data System (ADS)

    Tomkins, Andrew G.

    2007-08-01

    The relative importance of mechanical re-mobilisation, hydrothermal dissolution and re-precipitation, and sulphide melting in controlling redistribution of metals during concurrent metamorphism and deformation is evaluated at the middle amphibolite facies Montauban deposit in Canada. As at many other deposits, ductile deformation was important in driving mechanical re-mobilisation of massive sulphides from limb regions into hinge regions of large-scale folds and is thus the most important for controlling the economics of Pb and Zn distribution. Two possible stages of hydrothermally driven re-mobilisation are discussed, each of which produces characteristically different alteration assemblages. Prograde hydrothermal re-mobilisation is driven by pyrite de-sulphidation and concurrent chlorite dehydration and is thus an internally driven process. At Montauban, the H2S-rich fluid generated through this process allowed re-mobilisation of gold into the wall rock, where it was deposited in response to sulphidation of Fe Mg silicates. Retrograde hydrothermal re-mobilisation is an externally driven process, whereby large volumes of fluids from outside the deposit may dissolve and re-precipitate metals, and cause hydration of silicate minerals. This second hydrothermally driven process is not recognised at Montauban. Sulphide melting occurred as temperatures neared the peak metamorphic conditions. Melting initiated in the massive sulphides through arsenopyrite breakdown, and a small volume of melt was subsequently re-mobilised into the wall rock. Trace element partitioning and fractional crystallisation of this melt generated a precious metal-rich fractionate, which remained mobile until well after peak metamorphism. Thus, prograde hydrothermal re-mobilisation and sulphide melting were the most important mechanisms for controlling the distribution of Au and Ag.

  18. Ore geology and fluid inclusion geochemistry of the Tiemurt Pb-Zn-Cu deposit, Altay, Xinjiang, China: A case study of orogenic-type Pb-Zn systems

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zheng, Yi; Chen, YanJing

    2012-04-01

    The Tiemurt Pb-Zn-Cu deposit is hosted in a Devonian volcanic-sedimentary basin of the Altay orogenic belt, and is thus interpreted to have formed by sea-floor hydrothermal exhalation in previous studies. Our investigation discovered that the deposit is not stratiform or stratabound, but structure-controlled instead. The hydrothermal ore-forming process can be divided into the early, middle and late stage, represented by pyrite-quartz, polymetallic sulfide-quartz and carbonate-quartz veinlets, respectively. The early-stage veins and contained minerals are structurally deformed and brecciated, suggesting a compressional or transpressional tectonic regime. The middle-stage veinlets intrude and infill the fissures of the early-stage assemblages, and show no deformation, suggesting a tensional shear setting. The late-stage veinlets mostly infill open-space fissures that crosscut veins and replacements formed in the earlier stages. Four types of fluid inclusions (FIs), including aqueous (type W), carbonic-aqueous (type C), pure carbonic (type PC) and solid-bearing (type S), are identified at the Tiemurt deposit. The early-stage minerals contain the C- and W-type primary FIs that are totally homogenized at temperatures of 330-390 °C with low salinities of 0.8-11.9 wt.% NaCl eqv.; whilst the late-stage quartz or calcite contains only the W-type FIs with homogenization temperatures of 118-205 °C, and salinities of 1.4-3.4 wt.% NaCl eqv. This indicates that the ore fluid system evolved from CO2-rich, probably metamorphic to CO2-poor, meteoric fluids; and that a significant CO2-escape must have occurred. All the four types of FIs can be only observed in the middle-stage minerals, and even in a microscopic domain of a crystal, representing an association trapped from a boiling fluid system. These FIs homogenize at temperatures ranging from 270 to 330 °C, with two salinity clusters of 1.9-14.5 and 37.4-42.4 wt.% NaCl eqv., respectively. This implies that metal precipitation

  19. Chalcophile element partitioning between sulfide phases and hydrous mantle melt: Applications to mantle melting and the formation of ore deposits

    NASA Astrophysics Data System (ADS)

    Li, Yuan

    2014-11-01

    Understanding the geochemical behavior of chalcophile elements in magmatic processes is hindered by the limited partition coefficients between sulfide phases and silicate melt, in particular at conditions relevant to partial melting of the hydrated, metasomatized upper mantle. In this study, the partitioning of elements Co, Ni, Cu, Zn, As, Mo, Ag, and Pb between sulfide liquid, monosulfide solid solution (MSS), and hydrous mantle melt has been investigated at 1200 °C/1.5 GPa and oxygen fugacity ranging from FMQ-2 to FMQ+1 in a piston-cylinder apparatus. The determined partition coefficients between sulfide liquid and hydrous mantle melt are: 750-1500 for Cu; 600-1200 for Ni; 35-42 for Co; 35-53 for Pb; and 1-2 for Zn, As, and Mo. The partition coefficients between MSS and hydrous mantle melt are: 380-500 for Cu; 520-750 for Ni; ∼50 for Co; <0.5 for Zn; 0.3-6 for Pb; 0.1-2 for As; 1-2 for Mo; and >34 for Ag. The variation of the data is primarily due to differences in oxygen fugacity. These partitioning data in conjunction with previous data are applied to partial melting of the upper mantle and the formation of magmatic-hydrothermal Cu-Au deposits and magmatic sulfide deposits. I show that the metasomatized arc mantle may no longer contain sulfide after >10-14% melt extraction but is still capable of producing the Cu concentrations in the primitive arc basalts, and that the comparable Cu concentrations in primitive arc basalts and in MORB do not necessarily imply similar oxidation states in their source regions. Previous models proposed for producing Cu- and/or Au-rich magmas have been reassessed, with the conclusions summarized as follows. (1) Partial melting of the oxidized (fO2 > FMQ), metasomatized arc mantle with sulfide exhaustion at degrees >10-14% may not generate Cu-rich, primitive arc basalts. (2) Partial melting of sulfide-bearing cumulates in the root of thickened lower continental crust or lithospheric mantle does not typically generate Cu- and

  20. Ore Petrology and Alteration of the West Ansil Volcanic-hosted Massive Sulphide Deposit of the Noranda Mining Camp, Rouyn-Noranda, Quebec

    NASA Astrophysics Data System (ADS)

    Boucher, Stephanie M.

    The West Ansil deposit was the first Cu discovery in 25 years in the Noranda Central Camp. It has a combined indicated and inferred resource of ˜1.2 Mt. Grades for the indicated resource are 3.4% Cu, 0.4% Zn, 1.4 g/t Au and 9.2 g/t Ag. The bulk of the resource is located in three massive sulphide lenses (Upper, Middle and Lower) that are entirely within the Rusty Ridge Formation above the Lewis exhalite. The mineralization in all three ore lenses consists of massive pyrrhotite + chalcopyrite +/- magnetite. Semi-massive sphalerite is restricted to the upper and lower parts of the Middle lens. Massive magnetite occurs at the center of the Upper and Middle lenses, where it replaces massive pyrrhotite. A striking feature of West Ansil is the presence of abundant colloform and nodular pyrite (+/-marcasite) in the massive sulphides. Late-stage replacement of massive pyrrhotite by colloform pyrite and marcasite, occurs mostly along the upper and lower contacts of the lenses.

  1. Igneous activity and related ore deposits in the western and southern Tushar Mountains, Marysvale volcanic field, west-central Utah

    USGS Publications Warehouse

    Steven, Thomas A.

    1984-01-01

    PART A: Igneous activity in the Marysvale volcanic field of western Utah can be separated into many episodes of extrusion, intrusion, and hydrothermal activity. The rocks of the western Tushar Mountains, near the western part of the volcanic field, include intermediate-composition, calc-alkalic volcanic rocks erupted from scattered volcanoes in Oligocene through earliest Miocene time and related monzonitic intrusions emplaced 24-23 m.y. ago. Beginning 22-21 m.y. ago and extending through much of the later Cenozoic, a bimodal basalt-rhyolite assemblage was erupted widely throughout the volcanic field. Only volcanic and intrusive rocks belonging to the rhyolitic end member of this bimodal assemblage are present in the western Tushar Mountains; most of these rocks either fill the Mount Belknap caldera (19 m.y. old) or are part of the rhyolite of Gillies Hill (9---8 m.y. old). Episodic hydrothermal activity altered and mineralized rocks at many places in the western Tushar Mountains during Miocene time. The earliest activity took place in and adjacent to monzonitic calcalkalic intrusions emplaced in the vicinity of Indian Creek and Cork Ridge. These rocks were widely propylitized, and gold-bearing quartz-pyrite-carbonate veins formed in local fractures. Hydrothermal activity associated with the Mount Belknap caldera mobilized and redeposited uranium contained in the caldera-fill rocks and formed primary concentrations of lithophile elements (including molybdenum and uranium) in the vicinity of intrusive bodies. Hydrothermal activity associated with the rhyolite of Gillies Hill altered and mineralized rocks at several places along the fault zone that marks the western margin of the Tushar Mountains; the zoned alunite and gold deposits at Sheep Rock, the gold deposit at the Sunday Mine, and an alunite deposit near Indian Creek were thus produced. Resetting of isotopic ages suggests that another center of hydrothermally altered rocks associated with a buried pluton about

  2. A mixture of mantle and crustal derived He-Ar-C-S ore-forming fluids at the Baogutu reduced porphyry Cu deposit, western Junggar

    NASA Astrophysics Data System (ADS)

    Cao, MingJian; Qin, KeZhang; Li, GuangMing; Evans, Noreen J.; He, HuaiYu; Jin, LuYing

    2015-02-01

    Most large to huge porphyry Cu deposits (PCDs) are oxidized, making the Baogutu reduced porphyry Cu deposit (RPCD) a relative rarity. CH4-bearing ore-forming fluids formed at several hydrothermal stages, however, their source is still unclear. To address this issue, isotopic investigations of sulfide He-Ar-S and calcite C were conducted. Fluid inclusions hosted in sulfides (arsenopyrite, chalcopyrite and pyrite) showed 3He/4He ratios of 0.06-0.30 Ra (Ra is the 3He/4He ratio of air = 1.39 × 10-6), 40Ar/36Ar of 311-405, 40Ar∗/4He of 0.06-1.01, and F4He ratios of 902-11,074 (sample BGT-Py 2 yielded a ratio of 100), indicating a predominantly crustal source for the fluids with minor mantle input (less than 5%). The δ13C values of carbonate yielded a value of -7.8‰ (n = 3), implying that CO2 was probably sourced from mantle or juvenile lower crust. According to the restricted sulfide δ34S values, the total S isotopic composition of the hydrothermal system was estimated to be 0.0-0.5‰, suggesting that the sulfur was derived from mantle or lower crust magmatic source. According to the published granitoids Nd isotopic compositions at the Baogutu RPCD, fairly young TDM model ages (450-650 Ma) suggest that the granitoids were derived from partial melting of a juvenile basaltic lower crust. Thus, we propose that small proportion of mantle-derived fluids (less than 5%), probably rise up and then mix with the fluids of juvenile lower crust under an extensional tectonic setting, forming the mantle-derived Sr-Nd-Pb-S-C but crustal He-Ar isotopic compositions.

  3. Calcium chloride brines: The vital component in the hydrothermal brine-hydrothermal ore deposit-evaporite-basinal brine cycle in continental rift basins

    SciTech Connect

    Hardie, L. . Dept. of Earth and Planetary Science)

    1992-01-01

    Nonmarine evaporites are forming today in chloride-rich saline lakes in a number of arid continental rift and strike-slip basins that are characterized by upwelling of subsurface CaCl[sub 2]-bearing brines driven by forced convection of cool basinal brines or by free convection of hydrothermal brines which reach the surface as brine springs. The compositions of these upwelling brines are distinctively different from that of seawater or typical continental waters due primarily to their high proportion of Ca and low proportion of SO[sub 4]. The most viable explanation for the CaCl[sub 2] composition of these upwelling brines is the interaction between hot convecting groundwaters and bedrock at or above zeolite facies temperatures, as for example occurs in the modern Salton Sea basin. Such upwelling CaCl[sub 2] brines in extensional fault basins can explain the puzzling chemical composition of MgSO[sub 4]-poor potash evaporites, the least understood of all ancient salt deposits. In this regard it is suggested that the following cyclic succession of processes occurs in active continental rift basins during a magmatically-driven thermal event: (1) hydrothermal convection of the ambient porewaters in the rift sediments, (2) dissolution of buried evaporites and hydrothermal metamorphism of the rift sediments, (3) hydrothermal ore deposition in fault-related fractures and within the rift sediments, (4) upwelling brine springs add CaCl[sub 2] and KCl components to the surface lake waters, which on evaporation produce MgSO[sub 4]-poor potash evaporites, (5) decay of the thermal event leads to cool down of the hot brines, which now migrate gravitationally to the deeper parts of the basin to become static Na-Ca-Cl basinal brines.

  4. Estimating gold-ore mineralization potential within Topolninsk ore field (Gorny Altai)

    NASA Astrophysics Data System (ADS)

    Timkin, T.; Voroshilov, V.; Askanakova, O.; Cherkasova, T.; Chernyshov, A.; Korotchenko, T.

    2015-11-01

    Based on the results of ore and near-ore metasomatite composition analysis, the factors and indicators of gold-ore mineralization potential were proposed. Integration of the obtained data made it possible to outline magmatic, structural, and lithological factors, as well as direct and indirect indicators of gold-ore mineralization. Applying multidimensional analysis inherent to geochemical data, the spatial structure was investigated, as well as the potential mineralization was identified. Based on the developed and newly-identified mineralization, small (up to medium-sized) mineable gold-ore deposits in skarns characterized by complex geological setting was identified.

  5. Mineralogical, fluid inclusion, and stable isotope constraints on mechanisms of ore deposition at the Samgwang mine (Republic of Korea)—a mesothermal, vein-hosted gold-silver deposit

    NASA Astrophysics Data System (ADS)

    Yoo, Bong Chul; Lee, Hyun Koo; White, Noel C.

    2010-02-01

    The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized, temporally separated by a major faulting event. The ore minerals occur in quartz and calcite of stage I, associated with fracturing and healing of veins. Hydrothermal wall-rock alteration minerals of stage I include Fe-rich chlorite (Fe/(Fe+Mg) ratios 0.74-0.81), muscovite, illite, K-feldspar, and minor arsenopyrite, pyrite, and carbonates. Sulfide minerals deposited along with electrum during this stage include arsenopyrite, pyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, argentite, pyrargyrite, and argentian tetrahedrite. Only calcite was deposited during stage II. Fluid inclusions in quartz contain three main types of C-O-H fluids: CO2-rich, CO2-H2O, and aqueous inclusions. Quartz veins related to early sulfides in stage I were deposited from H2O-NaCl-CO2 fluids (1,500-5,000 bar, average 3,200) with T htotal values of 200°C to 383°C and salinities less than about 7 wt.% NaCl equiv. Late sulfide deposition was related to H2O-NaCl fluids (140-1,300 bar, average 700) with T htotal values of 110°C to 385°C and salinities less than about 11 wt.% NaCl equiv. These fluids either evolved through immiscibility of H2O-NaCl-CO2 fluids as a result of a decrease in fluid pressure, or through mixing with deeply circulated meteoric waters as a result of uplift or unloading during mineralization, or both. Measured and calculated sulfur isotope compositions (δ34SH2S = 1.5 to 4.8‰) of hydrothermal fluids from the stage I quartz veins indicate that ore sulfur was derived mainly from a magmatic source. The calculated and measured oxygen and hydrogen isotope compositions (δ18OH2O

  6. LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac - Saint-Salvy deposit (France): Insights into incorporation mechanisms and ore deposition processes

    NASA Astrophysics Data System (ADS)

    Belissont, Rémi; Boiron, Marie-Christine; Luais, Béatrice; Cathelineau, Michel

    2014-02-01

    sphalerite varies from -2.07 ± 0.37‰ to +0.91 ± 0.16‰ (2σ SD) and positively correlates with bulk Ge content. This indicates considerable Ge isotopic fractionation within sphalerite during low-T hydrothermal deposition and zoning processes, associated with possible microscale open system fluid mixing. The trace element features in sphalerite from Saint-Salvy compared with those of other deposits confirm their use as discriminators among genetic types of ores (e.g., high In contents for magmatic-related deposits, and Ge for low-temperature deposits). The LA-ICP-MS technique is revealed to be a powerful tool to measure in situ trace and minor elements occurring as solid solutions in sphalerite. The 74Ge isotope is most relevant for Ge analysis using the LA-ICP-MS, as this isotope shows the lowest isobaric interferences. Principal component analysis (PCA) of LA-ICP-MS dataset revealed an antithetic distribution of element clusters in sphalerite: Cu and trace elements Ge, Sb, Ag, and As are enriched and positively correlated in sector zoning whereas Fe, Cd, In and Sn are enriched in dark brown rhythmic bands. This distribution implies crystallographic controls on the incorporation of trace elements. Regardless of the zoning type, all spots considered, notable coupled substitutions have been suggested from binary scatter plots: 2Zn2+ ↔ Cu+ + Sb3+ and 3Zn2+ ↔ Ge4+ + 2Ag+. Also, the data suggest the substitution 3Zn2+ ↔ In3+ + Sn3+ + □ although Sn oxidation state needs verification using appropriate methods (e.g., XAS, μ-XANES/EXAFS). Fe and Cd are mainly involved in direct Zn2+ ↔ (Fe2+, Cd2+) substitutions. Noticeably, in all spots, Cu content approaches the sum of all available tri- and tetravalent cations. In this way, Cu (occurring as Cu+) could provide charge-balance for the entire broad set of coupled substitution mechanisms responsible for incorporation of the whole range of trace elements in Saint-Salvy sphalerite, especially Ge, Ga and Sb. Germanium

  7. Elemental imaging of organic matter and associated metals in ore deposits using micro PIXE and micro-EBS

    NASA Astrophysics Data System (ADS)

    Fuchs, S.; Przybylowicz, W. J.; Williams-Jones, A. E.

    2014-01-01

    Micro-PIXE and micro-EBS analyses were carried out on samples from the Au-U-bearing Carbon Leader Reef of the Witwatersrand in South Africa to investigate the role of organic matter in the formation of this deposit. Micro-PIXE and Micro-EBS shows a very complex metal distribution within the bitumen nodules and their interstitial spaces. The style of the gold distribution and its association with epigenetic minerals (REE phosphates, phyllosilicates) indicates that all observed gold migrated in aqueous solution and precipitated by reduction on the surfaces of the bitumen nodules. Uraninite occurrences are confined to the bitumen nodules, which supports the argument of a uraninite paleo-placer; however the pervasive distribution of uranium also supports the argument that uraninite is derived from organo-metallic complexes. This study shows that micro-PIXE is a powerful tool to characterize metals associated with hydrocarbons. However, the organic matrix, the complexity of the obtained spectra and the small size of the minerals have significant influence on the reliability of the quantitative data. Due to highly variable amounts of heavy metals (U, Au, Pb) the obtained micro-EBS results are of questionable quality.

  8. In situ Sr isotope analysis of apatite by LA-MC-ICPMS: constraints on the evolution of ore fluids of the Yinachang Fe-Cu-REE deposit, Southwest China

    NASA Astrophysics Data System (ADS)

    Zhao, Xin-Fu; Zhou, Mei-Fu; Gao, Jian-Feng; Li, Xiao-Chun; Li, Jian-Wei

    2015-10-01

    Apatite is a ubiquitous accessory mineral in a variety of rocks and hydrothermal ores. Strontium isotopes of apatite are well known to retain petrogenetic information and have been widely used to investigate the origin of igneous rocks, but such attempts have rarely been made to constrain ore-forming processes of hydrothermal systems. We here report in situ LA-MC-ICPMS Sr isotope data of apatite from the ~1660-Ma Yinachang Fe-Cu-REE deposit, Southwest China. The formation of this deposit was coeval to the emplacement of regionally distributed doleritic intrusions within a continental-rift setting. The deposit has a paragenetic sequence consisting of sodic alteration (stage I), magnetite mineralization (stage II), Cu sulfide and REE mineralization (stage III), and final barren calcite veining (stage IV). The stage II and III assemblages contain abundant apatite, allowing to investigate the temporal evolution of the Sr isotopic composition of the ore fluids. Apatite of stage II (Apt II) is associated with fluorite, magnetite, and siderite, whereas apatite from stage III (Apt III) occurs intimately intergrown with ankerite and Cu sulfides. Apt II has 87Sr/86Sr ratios varying from 0.70377 to 0.71074, broadly compatible with the coeval doleritic intrusions (0.70592 to 0.70692), indicating that ore-forming fluids responsible for stage II magnetite mineralization were largely equilibrated with mantle-derived mafic rocks. In contrast, Apt III has distinctly higher 87Sr/86Sr ratios from 0.71021 to 0.72114, which are interpreted to reflect external radiogenic Sr, likely derived from the Paleoproterozoic strata. Some Apt III crystals have undergone extensive metasomatism indicated by abundant monazite inclusions. The metasomatized apatite has much higher 87Sr/86Sr ratios up to 0.73721, which is consistent with bulk-rock Rb-Sr isotope analyses of Cu ores with 87Sr/86Sri from 0.71906 to 0.74632. The elevated 87Sr/86Sr values of metasomatized apatite and bulk Cu ores indicate

  9. Possible lunar ores

    NASA Technical Reports Server (NTRS)

    Gillett, Stephen L.

    1991-01-01

    Despite the conventional wisdom that there are no lunar ores, geochemical considerations suggest that local concentrations of useful rare elements exist on the Moon in spite of its extreme dryness. The Moon underwent protracted igneous activity in its history, and certain magmatic processes can concentrate incompatible elements even if anhydrous. Such processes include: (1) separation of a magma into immiscible liquid phases (depending on composition, these could be silicate-silicate, silicate-oxide, silicate-sulfide, or silicate-salt); (2) cumulate deposits in layered igneous intrusions; and (3) concentrations of rare, refractory, lithophile elements (e.g., Be, Li, Zr) in highly differentiated, silica-rich magmas, as in the lunar granites. Terrestrial mining experience indicates that the single most important characteristic of a potential ore is its concentration of the desire element. The utility of a planet as a resource base is that the welter of interacting processes over geologic time can concentrate rare element automatically. This advantage is squandered if adequate exploration for ores is not first carried out.

  10. The sources of our iron ores. II

    USGS Publications Warehouse

    Burchard, E.F.

    1933-01-01

    In this instalment** the iron ore deposits of the Lake Superior States, which normally furnish about 80 per cent, of the annual output of the United States, are described together with historical notes on discovery and transportation of ore. Deposits in the Mississippi Valley and Western States are likewise outlined and the sources of imported ore are given. Reviewing the whole field, it is indicated that the great producing deposits of the Lake Superior and southern Appalachian regions are of hematite in basin areas of sedimentary rocks, that hydrated iron oxides and iron carbonates are generally found in undisturbed comparatively recent sediments, and that magnetite occurs in metamorphic and igneous rocks; also that numerical abundance of deposits is not a criterion as to their real importance as a source of supply. Statistics of production of iron ore and estimates of reserves of present grade conclude the paper.

  11. Environment of ore deposition in the creede mining district, San Juan Mountains, Colorado: Part V. Epithermal mineralization from fluid mixing in the OH vein

    USGS Publications Warehouse

    Hayba, D.O.

    1997-01-01

    Detailed fluid inclusion studies on coarse-grained sphalerite from the OH vein, Creede, Colorado, have shown that the abrupt color changes between growth zones correspond to abrupt changes in the nature of the ore fluids. Within each growth zone, however, the composition of the fluids remained constant. The base of a distinctive orange-brown growth zone marks a sharp increase in both temperature and salinity relative to the preceding yellow-white zone. The orange-brown growth zone can be correlated along much of the vein and is believed to represent a time-stratigraphic interval. Along the vein, temperatures and salinities of fluid inclusions within this interval show a systematic decrease from about 285??C and 11.5 wt percent NaCl equiv near the base of the vein to about 250??C and 8 wt percent NaCl equiv, respectively, near the top of the vein. The iron concentration of this sphalerite growth zone shows a similar pattern, decreasing from about 2.8 to 1.2 mole percent FeS. When plotted on an enthalpy-salinity diagram, the fluid inclusion data define a spatial trend indicating the progressive mixing of deeply circulating hydrothermal brines with overlying, dilute ground waters. The hydrothermal brines entered the OH vein from below at a temperature, salinity, and density of approximately 285??C, 11.5 wt percent NaCl equiv, and 860 kg/m3, respectively, whereas the overlying ground waters appear to have been preheated to roughly 150??C and had an assumed salinity of 0 wt percent and a density of 920 kg/m3. The greater density of the heated ground water promoted mixing with the hydrothermal brine within the open fractures, causing sphalerite deposition. Although there were also episodes of boiling during vein mineralization, boiling appears unimportant for this sphalerite. Isotopic evidence and geochemical modeling studies also indicate that mixing was the depositional mechanism for sphalerite. An important aspect of the mixing hydrology of the Creede system involves

  12. Constraints of mineralogical characterization of gold ore: Implication for genesis, controls and evolution of gold from Kundarkocha gold deposit, eastern India

    NASA Astrophysics Data System (ADS)

    Sahoo, P. R.; Venkatesh, A. S.

    2015-01-01

    Gold mineralization in Kundarkocha gold deposit occurs in the eastern Indian Craton that is hosted by sheared quartz-carbonate-sulfide veins emplaced within the graphitic schist, carbonaceous phyllite and talc-chlorite-serpentine schist belongs to Gorumahisani-Badampahar schist belt of Iron Ore Group. Gold mineralization exhibits both lithological and structural controls in the study area, albeit the stratigraphic control is more ubiquitously observed. Detailed mineralogical characterization coupled with electron probe microanalysis of the sulfide phases reveal the occurrences of gold in three distinct forms (i) as lattice-bound form within sulfides especially enriched in arsenopyrite, loellingite, pyrite, pyrrhotite and chalcopyrite in decreasing order of abundance; (ii) as micro inclusions or nano-scale gold inclusions within pyrite and arsenopyrite especially along the growth zones and micro-fractures as substrates and (iii) as free milling nugget gold grains either along the grain boundaries of sulfides or within the host rocks. Three generations of pyrite (Py-I, Py-II and Py-III) and arsenopyrite (Asp-I, Asp-II, Asp-III) have been identified based on textural, morphological characteristics and mineral chemistry. The lattice-bound gold content in pyrite and arsenopyrite varies from 600 to 2700 ppm and 900 to 3600 ppm respectively and increase in concentration of such refractory gold is seen in the order of chalcopyrite > pyrrhotite > pyrite > loellingite/arsenopyrite. The evolutionary stages of different forms of gold include remobilization of the lattice-bound grains in pyrite and arsenopyrite (Py-I and Asp-I) and re-concentration along the zoned-pyrite and arsenopyrite (Py-II and Asp-II) and ultimately as native gold/nuggets surrounding the sulfides as well as within the main mineralized zone. Lattice-bound gold distribution could have resulted due to metamorphic devolatilization reactions which are further aided by the influx of hydrothermal fluids. These

  13. Retrograde Evolution of the Hemlo Gold Deposit, Ontario: Fractional Crystallization of a Sulfide Melt and Remobilization of Ore-Related Metals

    NASA Astrophysics Data System (ADS)

    Heiligmann, M.; Clark, J. R.; Williams-Jones, A. E.

    2003-12-01

    The Hemlo gold deposit is a greenstone-hosted, lode-gold system in north-central Ontario, Canada. The main stage of gold mineralization occurred prior to peak, amphibolite-facies metamorphism, and is characterized by disseminated Au-Mo in potassically altered, barite- and pyrite-rich schists. Locally extensive remobilization of this ore occurred at or immediately after peak metamorphism ( ˜630° C, 5-6 kb), and is represented by minerals such as stibnite, realgar, orpiment, zinkenite and cinnabar, which are unstable at high temperature. Volumetrically minor gold was subsequently precipitated in calc-silicate zones at ˜400° C. Minerals reflecting early remobilization occur either at grain boundaries or as solid inclusions along healed fractures devoid of fluid inclusions. Planes of solid inclusions, many of which are polyphase, radiate locally from the boundaries of large polyphase sulfide aggregates. Inclusions containing both liquid and sulfides are observed mainly at intersections of planes of solid-only and liquid-vapor inclusions. Solid inclusions are characterized by complex assemblages in the system As-Sb-Pb-S, that reflect contrasting conditions of fS2 and fO2. The low thermal stability of many of these minerals, the absence of liquid in the solid inclusion trails, the excessive hydrothermal solubility of stibnite above 300° C, and the evidence of contrasting fS2 and fO2 rule out hydrothermal processes as the cause of this remobilization. We therefore propose that the latter was the result of formation of an As-Sb-Pb-S melt, at or near peak metamorphic conditions, containing minor proportions of Au, Hg, Ag, Cu, Tl and Te, and support this hypothesis with results of preliminary experiments showing that realgar-stibnite-cinnabar-bearing solids homogenize to liquid at ˜435° C. The melt is envisaged to have formed as a result of exsolution of elements such as As, Sb and Au from arsenian pyrite during metamorphic recrystallization, melting of primary

  14. Source and evolution of ore-forming hydrothermal fluids in the northern Iberian Pyrite Belt massive sulphide deposits (SW Spain): evidence from fluid inclusions and stable isotopes

    NASA Astrophysics Data System (ADS)

    Sánchez-España, Javier; Velasco, Francisco; Boyce, Adrian J.; Fallick, Anthony E.

    2003-08-01

    A fluid inclusion and stable isotopic study has been undertaken on some massive sulphide deposits (Aguas Teñidas Este, Concepción, San Miguel, San Telmo and Cueva de la Mora) located in the northern Iberian Pyrite Belt. The isotopic analyses were mainly performed on quartz, chlorite, carbonate and whole rock samples from the stockworks and altered footwall zones of the deposits, and also on some fluid inclusion waters. Homogenization temperatures of fluid inclusions in quartz mostly range from 120 to 280 °C. Salinity of most fluid inclusions ranges from 2 to 14 wt% NaCl equiv. A few cases with Th=80-110 °C and salinity of 16-24 wt% NaCl equiv., have been also recognized. In addition, fluid inclusions from the Soloviejo Mn-Fe-jaspers (160-190 °C and ≈6 wt% NaCl equiv.) and some Late to Post-Hercynian quartz veins (130-270 °C and ≈4 wt% NaCl equiv.) were also studied. Isotopic results indicate that fluids in equilibrium with measured quartz (δ18Ofluid ≈-2 to 4‰), chlorites (δ18Ofluid ≈8-14‰, δDfluid ≈-45 to -27‰), whole rocks (δ18Ofluid ≈4-7‰, δDfluid ≈-15 to -10‰), and carbonates (δ18Oankerite ≈14.5-16‰, δ13Cfluid =-11 to -5‰) evolved isotopically during the lifetime of the hydrothermal systems, following a waxing/waning cycle at different temperatures and water/rock ratios. The results (fluid inclusions, δ18O, δD and δ13C values) point to a highly evolved seawater, along with a variable (but significant) contribution of other fluid reservoirs such as magmatic and/or deep metamorphic waters, as the most probable sources for the ore-forming fluids. These fluids interacted with the underlying volcanic and sedimentary rocks during convective circulation through the upper crust.

  15. A Paleozoic anorthosite massif related to rutile-bearing ilmenite ore deposits, south of the Polochic fault, Chiapas Massif Complex, Mexico

    NASA Astrophysics Data System (ADS)

    Cisneros, A.; Ortega-Gutiérrez, F.; Weber, B.; Solari, L.; Schaaf, P. E.; Maldonado, R.

    2013-12-01

    The Chiapas Massif Complex in the southern Maya terrane is mostly composed of late Permian igneous and meta-igneous rocks. Within this complex in southern Mexico and in the adjacent San Marcos Department of Guatemala, south of the Polochic fault, several small outcrops (~10 km2) of a Phanerozoic andesine anorthosite massif were found following an E-W trend similar to the Polochic-Motagua Fault System. Such anorthosites are related to rutile-bearing ilmenite ore deposits and hornblendite-amphibolite bands (0.1-3 meters thick). The anorthosites show recrystallization and metamorphic retrogression (rutile with titanite rims), but no relicts of high-grade metamorphic minerals such as pyroxene or garnet have been found. In Acacoyagua, Chiapas, anorthosites are spatially related to oxide-apatite rich mafic rocks; in contrast, further to the west in Motozintla, they are related to monzonites. Zircons from these monzonites yield a Permian U-Pb age (271.2×1.4 Ma) by LA-MC-ICPMS. Primary mineral assemblage of the anorthosites include mostly medium to fine-grained plagioclase (>90%) with rutile and apatite as accessory minerals, occasionally with very low amounts of quartz. Massive Fe-Ti oxide lenses up to tens of meters in length and few meters thick are an ubiquitous constituent of these anorthosites and their mineralogy include ilmenite (with exsolution lamellae of Ti-magnetite), rutile, magnetite, clinochlore, ×spinel, ×apatite, ×zircon and srilankite (Ti2ZrO6, first finding of this phase in Mexico). Rutile occurs within the massive ilmenite in two morphological types: (1) fine-grained (5-40 μm) rutile along ilmenite grain boundaries or fractures, and (2) coarse-grained rutile (<5 mm) as discrete grains, whereas magnetite and srilankite only appear as small grains along ilmenite boundaries. Zircon is present as discontinuously aligned small grains (10-40 μm) forming rims around many rutile and ilmenite grains. Attempts to date zircon rims by U-Pb using LA

  16. Genetic implications of regional and temporal trends in ore fluid geochemistry of Mississippi Valley-type deposits in the Ozark region

    USGS Publications Warehouse

    Viets, J.G.; Leach, D.L.

    1990-01-01

    Fluids extracted from aqueous fluid inclusions in epigenetic gangue and ore minerals record the migration of huge volumes of highly saline fluids throughout the stratigraphic section of the Ozark region. The extracted fluids share many similarities regionally, but there are significant temporal differences which define two geochemically distinct end-member ore-forming fluids, referred to as the Viburnum Trend main stage or Viburnum Trend type and the Tri-State type. Possible explanations for the origins of these two end-member fluids are discussed. -from Authors

  17. Uranium mill ore dust characterization

    SciTech Connect

    Knuth, R.H.; George, A.C.

    1980-11-01

    Cascade impactor and general air ore dust measurements were taken in a uranium processing mill in order to characterize the airborne activity, the degree of equilibrium, the particle size distribution and the respirable fraction for the /sup 238/U chain nuclides. The sampling locations were selected to limit the possibility of cross contamination by airborne dusts originating in different process areas of the mill. The reliability of the modified impactor and measurement techniques was ascertained by duplicate sampling. The results reveal no significant deviation from secular equilibrium in both airborne and bulk ore samples for the /sup 234/U and /sup 230/Th nuclides. In total airborne dust measurements, the /sup 226/Ra and /sup 210/Pb nuclides were found to be depleted by 20 and 25%, respectively. Bulk ore samples showed depletions of 10% for the /sup 226/Ra and /sup 210/Pb nuclides. Impactor samples show disequilibrium of /sup 226/Ra as high as +-50% for different size fractions. In these samples the /sup 226/Ra ratio was generally found to increase as particle size decreased. Activity median aerodynamic diameters of the airborne dusts ranged from 5 to 30 ..mu..m with a median diameter of 11 ..mu..m. The maximum respirable fraction for the ore dusts, based on the proposed International Commission on Radiological Protection's (ICRP) definition of pulmonary deposition, was < 15% of the total airborne concentration. Ore dust parameters calculated for impactor duplicate samples were found to be in excellent agreement.

  18. 2.8-Ma ash-flow caldera at Chegem River in the northern Caucasus Mountains (Russia), contemporaneous granites, and associated ore deposits

    USGS Publications Warehouse

    Lipman, P.W.; Bogatikov, O.A.; Tsvetkov, A.A.; Gazis, C.; Gurbanov, A.G.; Hon, K.; Koronovsky, N.V.; Kovalenko, V.I.; Marchev, P.

    1993-01-01

    Diverse latest Pliocene volcanic and plutonic rocks in the north-central Caucasus Mountains of southern Russia are newly interpreted as components of a large caldera system that erupted a compositionally zoned rhyolite-dacite ash-flow sheet at 2.83 ?? 0.02 Ma (sanidine and biotite 40Ar/39Ar). Despite its location within a cratonic collision zone, the Chegem system is structurally and petrologically similar to typical calderas of continental-margin volcanic arcs. Erosional remnants of the outflow Chegem Tuff sheet extend at least 50 km north from the source caldera in the upper Chegem River. These outflow remnants were previously interpreted by others as erupted from several local vents, but petrologic similarities indicate a common origin and correlation with thick intracaldera Chegem Tuff. The 11 ?? 15 km caldera and associated intrusions are superbly exposed over a vertical range of 2,300 m in deep canyons above treeline (elev. to 3,800 m). Densely welded intracaldera Chegem Tuff, previously described by others as a rhyolite lava plateau, forms a single cooling unit, is > 2 km thick, and contains large slide blocks from the caldera walls. Caldera subsidence was accommodated along several concentric ring fractures. No prevolcanic floor is exposed within the central core of the caldera. The caldera-filling tuff is overlain by andesitic lavas and cut by a 2.84 ?? 0.03-Ma porphyritic granodiorite intrusion that has a cooling age analytically indistinguishable from that of the tuffs. The Eldjurta Granite, a pluton exposed low in the next large canyon (Baksan River) 10 km to the northwest of the caldera, yields variable K-feldspar and biotite ages (2.8 to 1.0 Ma) through a 5-km vertical range in surface and drill-hole samples. These variable dates appear to record a prolonged complex cooling history within upper parts of another caldera-related pluton. Major W-Mo ore deposits at the Tirniauz mine are hosted in skarns and hornfels along the roof of the Eldjurta Granite

  19. U-Pb zircon, geochemical and Sr-Nd-Hf-O isotopic constraints on age and origin of the ore-bearing intrusions from the Nurkazgan porphyry Cu-Au deposit in Kazakhstan

    NASA Astrophysics Data System (ADS)

    Shen, Ping; Pan, Hongdi; Seitmuratova, Eleonora; Jakupova, Sholpan

    2016-02-01

    Nurkazgan, located in northeastern Kazakhstan, is a super-large porphyry Cu-Au deposit with 3.9 Mt metal copper and 229 tonnage gold. We report in situ zircon U-Pb age and Hf-O isotope data, whole rock geochemical and Sr-Nd isotopic data for the ore-bearing intrusions from the Nurkazgan deposit. The ore-bearing intrusions include the granodiorite porphyry, quartz diorite porphyry, quartz diorite, and diorite. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating indicates that the granodiorite porphyry and quartz diorite porphyry emplaced at 440 ± 3 Ma and 437 ± 3 Ma, respectively. All host rocks have low initial 87Sr/86Sr ratios (0.70338-0.70439), high whole-rock εNd(t) values (+5.9 to +6.3) and very high zircon εHf(t) values (+13.4 to +16.5), young whole-rock Nd and zircon Hf model ages, and consistent and slightly high zircon O values (+5.7 to +6.7), indicating that the ore-bearing magmas derived from the mantle without old continental crust involvement and without marked sediment contamination during magma emplacement. The granodiorite porphyry and quartz diorite porphyry are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and depleted in high-field strength elements (HFSE), Eu, Ba, Nb, Sr, P and Ti. The diorite and quartz diorite have also LILE and LREE enrichment and HFSE, Nb and Ti depletion, but have not negative Eu, Ba, Sr, and P anomalies. These features suggest that the parental magma of the granodiorite porphyry and quartz diorite porphyry originated from melting of a lithospheric mantle and experienced fractional crystallization, whereas the diorite and quartz diorite has a relatively deeper lithospheric mantle source region and has not experienced strong fractional crystallization. Based on these, together with the coeval ophiolites in the area, we propose that a subduction of the Balkhash-Junggar oceanic plate took place during the Early Silurian and the ore-bearing intrusions and associated Nurkazgan

  20. Ores and Climate Change - Primary Shareholders

    NASA Astrophysics Data System (ADS)

    Stein, Holly J.; Hannah, Judith L.

    2015-04-01

    Many in the economic geology community concern themselves with details of ore formation at the deposit scale, whether tallying fluid inclusion data to get at changes in ore-forming fluids or defining structures that aid and abet mineralization. These compilations are generally aimed at interpretation of events at the site of ore formation, with the goal being assignment of the deposit to a sanctioned ore deposit model. While providing useful data, this approach is incomplete and does not, by itself, serve present-day requirements for true interdisciplinary science. The ore-forming environment is one of chaos and disequilibrium at nearly all scales (Stein, 2014). Chaos and complexity are documented by variably altered rocks, veins or disseminated mineralization with multi-generational fluid histories, erratic and unusual textures in host rocks, and the bitumen or other hydrocarbon products entwined within many ore deposits. This should give pause to our drive for more data as a means to find "the answer". The answer lies in the kind of data collected and more importantly, in the way we interpret those data. Rather than constructing an ever-increasing catalog of descriptive mutations on sanctioned ore deposit models (e.g., IOGC or Iron-Oxide Copper Gold deposits), the way forward is to link source and transport of metals, sulfur, and organic material with regional and ultimately whole Earth chemical evolution. Important experimental work provides chemical constraints in controlled and behaved environments. To these data, we add imagination and interpretation, always tying back to field observations. In this paper, several key points are made by way of ore deposit examples: (1) many IOCG deposits are outcomes of profound changes in the chemistry of the Earth's surface, in the interplay of the atmosphere, hydrosphere, biosphere, and lithosphere; (2) the redox history of Fe in deep earth may be ultimately expressed in the ore-forming sequence; and (3) the formation of

  1. Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis

    NASA Astrophysics Data System (ADS)

    Torresi, Ignacio; Xavier, Roberto Perez; Bortholoto, Diego F. A.; Monteiro, Lena V. S.

    2012-03-01

    The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g/t Au) lies in the southern sector of the Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW-ESE-striking, 60-km-long shear zone, close to the contact of the ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted by mafic and felsic metavolcanic rocks and crosscutting granitoid and gabbro intrusions that have been subjected to the following hydrothermal alteration sequence towards the ore zones: (1) poorly developed sodic alteration (albite and scapolite); (2) potassic alteration (biotite or K-feldspar) accompanied by magnetite formation and silicification; (3) widespread, pervasive chlorite alteration spatially associated with quartz-carbonate-sulphide infill ore breccia and vein stockworks; and (4) local post-ore quartz-sericite alteration. The ore assemblage is dominated by chalcopyrite (~60%), bornite (~10%), hematite (~20%), magnetite (10%) and subordinate chalcocite, native gold, Au-Ag tellurides, galena, cassiterite, F-rich apatite, xenotime, monazite, britholite-(Y) and a gadolinite-group mineral. Fluid inclusion studies in quartz point to a fluid regime composed of two distinct fluid types that may have probably coexisted within the timeframe of the Cu-Au mineralizing episode: a hot (>200°C) saline (32.8‰ to 40.6 wt.% NaCl eq.) solution, represented by salt-bearing aqueous inclusions, and a lower temperature (<200°C), low to intermediate salinity (<15 wt.% NaCl eq.) aqueous fluid defined by two-phase (LH2O + VH2O) fluid inclusions. This trend is very similar to those defined for other IOCG systems of the Carajás Mineral Province. δ 18OH2O values in equilibrium with calcite (-1.0‰ to 7.5‰ at 277°C to 344°C) overlap the lower range for primary magmatic waters, but the more 18O-depleted values also point to the involvement of externally derived fluids, possibly of meteoric origin

  2. Application of LANDSAT satellite imagery for iron ore prospecting in the western desert of Egypt

    NASA Technical Reports Server (NTRS)

    Elshazly, E. M.; Abdel-Hady, M. A.; Elghawaby, M. A.; Khawasik, S. M. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. The delineation of the geological units and geological structures through image interpretation, corroborated by field observations and structural analysis, led to the discovery of new iron ore deposits. A new locality for iron ore deposition, namely Gebel Qalamun, was discovered, as well as new occurrences within the already known iron ore region of Bahariya Oasis.

  3. [Infrared Spectra Characteristics of the Silicate Nickel Ores: A Comparison Study on Different Ore Samples from Indonesia and China].

    PubMed

    Yang, Meng-li; Fu, Wei; Wang, Bao-hua; Zhang, Ya-qian; Huang, Xiao-rong; Niu, Hu-jie

    2015-03-01

    The silicate nickel ores developed in the lateritic nickel deposit, from Kolonodale, Sulawesi Island, Indonesia, and Yuanjiang, Yunnan province, China, were selected for the present study. The X-ray diffraction and Fourier infrared spectra were used to analyze the mineralogical attribute of laterite nickel ores from two different places. The results show that these two different silicate nickel ores have unique infrared spectra characteristics individually, which contributes to the ore classification. The silicate nickel ores from Kolonodale deposit, Indonesia, can be classified as the serpentine type, the montmorillonite + serpentine type, and the garnierite type. While, the silicate nickel ores from Yuanjiang deposit, China, can be classified as the serpentine type and the talc + serpentine type. Moreover, the mineral crystallinity of Yuanjiang nickel ores is generally better than Kolonodale nickel ores. According to the advantage of infrared absorption spectra in distinguishing mineral polytypes, it can be determined that lizardite is the main mineral type in the silicate nickel ores of the two deposits, and there is no obvious evidence of chrysotile and antigorite's existence. The characteristic of infrared absorption spectra also shows that frequency change of OH libration indicates Ni (Fe) replacing Mg in the serpentine type nickel-bearing mineral, that is, OH libration of serpentine moves to higher frequency, with the proportion of Ni (Fe) replacing Mg increasing. PMID:26117869

  4. [Infrared Spectra Characteristics of the Silicate Nickel Ores: A Comparison Study on Different Ore Samples from Indonesia and China].

    PubMed

    Yang, Meng-li; Fu, Wei; Wang, Bao-hua; Zhang, Ya-qian; Huang, Xiao-rong; Niu, Hu-jie

    2015-03-01

    The silicate nickel ores developed in the lateritic nickel deposit, from Kolonodale, Sulawesi Island, Indonesia, and Yuanjiang, Yunnan province, China, were selected for the present study. The X-ray diffraction and Fourier infrared spectra were used to analyze the mineralogical attribute of laterite nickel ores from two different places. The results show that these two different silicate nickel ores have unique infrared spectra characteristics individually, which contributes to the ore classification. The silicate nickel ores from Kolonodale deposit, Indonesia, can be classified as the serpentine type, the montmorillonite + serpentine type, and the garnierite type. While, the silicate nickel ores from Yuanjiang deposit, China, can be classified as the serpentine type and the talc + serpentine type. Moreover, the mineral crystallinity of Yuanjiang nickel ores is generally better than Kolonodale nickel ores. According to the advantage of infrared absorption spectra in distinguishing mineral polytypes, it can be determined that lizardite is the main mineral type in the silicate nickel ores of the two deposits, and there is no obvious evidence of chrysotile and antigorite's existence. The characteristic of infrared absorption spectra also shows that frequency change of OH libration indicates Ni (Fe) replacing Mg in the serpentine type nickel-bearing mineral, that is, OH libration of serpentine moves to higher frequency, with the proportion of Ni (Fe) replacing Mg increasing.

  5. Tourmaline as a recorder of ore-forming processes

    USGS Publications Warehouse

    Slack, J.F.; Trumbull, R.B.

    2011-01-01

    Tourmaline occurs in diverse types of hydrothermal mineral deposits and can be used to constrain the nature and evolution of ore-forming fl uids. Because of its broad range in composition and retention of chemical and isotopic signatures, tourmaline may be the only robust recorder of original mineralizing processes in some deposits. Microtextures and in situ analysis of compositional and isotopic variations in ore-related tourmaline provide valuable insights into hydrothermal systems in seafl oor, sedimentary, magmatic, and metamorphic environments. Deciphering the hydrothermal record in tourmaline also holds promise for aiding exploration programs in the search for new ore deposits.

  6. 3D modelling and sheath folding at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    NASA Astrophysics Data System (ADS)

    Kampmann, Tobias C.; Stephens, Michael B.; Weihed, Pär

    2016-06-01

    Altered and mineralized rocks at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic Bergslagen ore district in the south-western part of the Fennoscandian Shield, have been metamorphosed at low-pressure, amphibolite-facies conditions and affected by ductile deformation. Using combined surface mapping of lithology and structure, drill core logging and microstructural work, the polyphase (D1 and D2) ductile deformation is demonstrated and a 3D model for the deposit created. Mineral associations include quartz, biotite, cordierite, anthophyllite, and minor almandine, andalusite and chlorite in silicate-rich altered rock, calcite or dolomite in marble and tremolite-actinolite or diopside-hedenbergite in skarn. The silicate minerals show varying growth patterns during the different phases of the tectonothermal evolution, with considerable static grain growth occurring between D1 and D2, and even after D2. F2 sheath folding along axes that plunge steeply to the SSE, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, cone- to rod-shaped mineralized bodies. This contrasts with a previous structural model invoking fold interference. A major shear zone with talc-chlorite-(quartz-biotite) mineral association separates the northern and southern structural domains at the deposit and bounds the polymetallic massive sulphides to the north.

  7. Research of Geochemical Associations of Nephelin Ores

    NASA Astrophysics Data System (ADS)

    Vulf, M.; Simonov, K.; Sazonov, A.

    The instant paper concerns research of distribution petrogenic chemical members in urtit ore body of Kia-Shaltyrsk deposit. Rocks of the deposit are ore for producing alum earth. Actuality of the subject based on outlooks of detection noble metal ore-bearing (Au, Pt, Pd, Rh, Ru) in alkaline rocks of Siberia, including rocks of Kia-Shaltyrsk deposit (Kuznetsk Alatau). The main purpose of analysis of distribution of members is directed to detection of a non-uniformity of distribution of substance and segments enriched with alum earth and noble members. The basic solved problems are following: o Creation regression models of ore body; o Definition of cumulative distribution functions of members in a contour of ore body; o The analysis of the obtained outcomes in geologic terms. For construction regression models the full-scale data was used, which was presented by the results of the spectral and silicate analyses of gold and petrogenic members containing 130 assays arranged in ore body. A non-linear multiparameter model of the ore body based on components of nephelin ore using neural net approach was constructed. For each member the corresponding distribution function is produced. The model is constructed on the following members: Au, Al2O3, SiO2, Fe2O3, CaO, MgO, SO3, R2O ((Na2O+K2O) -1) and losses of burning. The error of model forecasting membersS concentrations was from 0.02 up to 20%. Large errors basically connected with assays located near contact of ore body and ad- jacent strata or with very high concentrations of members; also they can be connected with different genesis of rocks or superposition of other processes. The analysis of concentrations of members and normalised absolute errors of the fore- cast has shown, that all members can be sectioned into two groups: first: Al2O3, SiO2, R2O, Fe2O3 and second: Au, losses of burning, CaO, MgO, SO3. The distribution of 1 gold is tightly connected with calcium and losses of burning and spatially linked with zones

  8. Antimony ore in the Fairbanks district, Alaska

    USGS Publications Warehouse

    Killeen, Pemberton Lewis; Mertie, John B.

    1951-01-01

    Antimony-bearing ores in the Fairbanks district, Alaska, are found principally in two areas, the extremities of which are at points 10 miles west and 23 miles northeast of Fairbanks; and one of two minor areas lies along this same trend 30 miles farther to the northeast. These areas are probably only local manifestations of mineralization that affected a much broader area and formed antimony-bearing deposits in neighboring districts, the closest of which is 50 miles away. The ores were exposed largely as a result of lode gold mining, but at two periods in the past, high prices for antimony ore warranted an independent production and about 2500 tons of stibnite ore was shipped. The sulfide deposits occupy the same fractures along which a gold-quartz mineralization of greater economic importance occurred; and both are probably genetically related to igneous rocks which intrude the schistose country rock. The sulfide is in part contemporaneous with some late-stage quartz in which it occurs as disseminated crystals; and in part the latest filling in the mineralized zones where it forms kidney-shaped masses of essentially solid sulfide. One extremely long mass must have contained nearly 100 tons of ore, but the average of the larger kidneys is closer to several tons. Much of the ore is stibnite, with quartz as a minor impurity, and assays show the tenor to vary from 40 to 65 percent antimony. Sulphantimonites are less abundant but likewise occur as disseminated crystals and as kidney-shaped bodies. Antimony oxides appear on the weathered surface and along fractures within the sulfide ore. Deposits containing either stibnite or sulphantimonite are known at more than 50 localities, but only eighteen have produced ore and the bulk of this came from the mines. The geology of the deposit, and the nature, extent, and period of the workings are covered in the detailed descriptions of individual occurrences. Several geologic and economic factors, which greatly affect

  9. The indirect electrochemical refining of lunar ores

    NASA Technical Reports Server (NTRS)

    Semkow, Krystyna W.; Sammells, Anthony F.

    1987-01-01

    Recent work performed on an electrolytic cell is reported which addresses the implicit limitations in various approaches to refining lunar ores. The cell uses an oxygen vacancy conducting stabilized zirconia solid electrolyte to effect separation between a molten salt catholyte compartment where alkali metals are deposited, and an oxygen-evolving anode of composition La(0.89)Sr(0.1)MnO3. The cell configuration is shown and discussed along with a polarization curve and a steady-state current-voltage curve. In a practical cell, cathodically deposited liquid lithium would be continuously removed from the electrolytic cell and used as a valuable reducing agent for ore refining under lunar conditions. Oxygen would be indirectly electrochemically extracted from lunar ores for breathing purposes.

  10. Appraisal of the accuracy of U.S. Geological Survey ore reserve estimates for uranium-vanadium deposits on the Colorado Plateau

    USGS Publications Warehouse

    Bush, Alfred Lerner; Stager, Harold Keith

    1954-01-01

    The U.S. Geological Survey has made estimates of the reserves of uranium and vanadium in the carnotite deposits explored by Geological Survey drilling on the Colorado Plateau. This report presents an appraisal of the accuracy of the reserve estimates for deposits in the Uravan mineral belt, the causes of inaccuracy, and the significance of the estimates in terms of the total known reserves of the region.

  11. Field study and three-dimensional reconstruction of thrusts and strike-slip faults in the Central Andes: implications for deep-seated geothermal circulation and ore deposits exploration

    NASA Astrophysics Data System (ADS)

    Norini, Gianluca; Groppelli, Gianluca; Giordano, Guido; Baez, Walter; Becchio, Raul; Viramonte, Jose; Arnosio, Marcelo

    2014-05-01

    The Puna plateau (NW Argentina), located in the back-arc of the Central Andes, is a plateau characterized by both orogen-parallel and orogen-oblique deformation styles, extensive magmatic and geothermal activity, and the broad occurrence of igneous and hydrothermal ore-forming minerals. In this area, like in other convergent margins, the behaviour of the magma-tectonics interplay can affect the circulation of hydrothermal fluids, so that the full comprehension of the tectonic control on the magmas and fluids paths in the continental crust is crucial to plan the geothermal and ore exploration. In this study, we present a structural analysis of the back-arc portion of the orogen-oblique Calama-Olacapato-El Toro fault system and the surrounding orogen-parallel thrust faults in the central-eastern Puna Plateau, comprising the Cerro Tuzgle-Tocomar geothermal volcanic area, with high geothermal potential, and silicic calderas and domes associated with epithermal ore deposits. We also focused on the tectonic and volcanotectonic structures of the Chimpa and Tuzgle stratovolcanoes, two of the most important polygenetic volcanic centres of the plateau. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of the tectonic structures of the studied area. These data and the available stratigraphic and geophysical data have been integrated with the software MOVE and PETREL in a three-dimensional reconstruction of the main fault planes, showing their attitude and intersections at depth. As a result of our study, we show that despite different geometry and kinematics of the Calama-Olacapato-El Toro fault system and the thrust faults, they formed and evolved under the same progressive evolving dynamic state, forming a single tectonic system and accommodating crustal shortening of a thickened crust. In this frame, the crust underwent simultaneous deformation along both the low-angle thrust faults and the vertical transcurrent strike-slip faults

  12. Reduction kinetics of aqueous U(VI) in acidic chloride brines to uraninite by methane, hydrogen or C-graphite under hydrothermal conditions: Implications for the genesis of unconformity-related uranium ore deposits

    NASA Astrophysics Data System (ADS)

    Dargent, Maxime; Truche, Laurent; Dubessy, Jean; Bessaque, Gilles; Marmier, Hervé

    2015-10-01

    The formation of hydrothermal uranium ore deposits involves the reduction of dissolved U(VI)(aq) to uraninite. However, the nature of the reducing agent and the kinetics of such a process are currently unknown. These questions are addressed through dedicated experiments performed under conditions relevant for the genesis of unconformity-related uranium (URU) deposits. We tested the efficiency of the following potential reductants supposed to be involved in the reaction: H2, CH4, C-graphite and dissolved Fe(II). Results demonstrate the great efficiency of H2, CH4 and C-graphite to reduce U(VI)(aq) into uraninite in acidic chloride brines, unlike dissolved Fe(II). Times needed for H2 (1.4 bar), CH4 (2.4 bar) and C-graphite (water/carbon mass ratio = 10) to reduce 1 mM of U(VI)(aq) in an acidic brine (1 m LiCl, pH ≈ 1 fixed by HCl) to uraninite at 200 °C are 12 h, 3 days and 4 months, respectively. The effects of temperature (T) between 100 °C and 200 °C, H2 partial pressure (0.14, 1.4, and 5.4 bar), salinity (0.1, 1 and 3.2 m LiCl) and pH at 25 °C (0.8 and 3.3) on the reduction rate were also investigated. Results show that increasing temperature and H2 partial pressure increase the reaction rate, whereas increasing salinity or pH have the reverse effect. The reduction of uranyl to uraninite follows an apparent zero-order with respect to time, whatever the considered electron donor. From the measured rate constants, the following values of activation energy (Ea), depending on the nature of the electron donor, have been derived: EaC-graphite = 155 ± 3 kJ mol-1, EaCH4 = 143 ± 6 kJ mol-1, and EaH2 = 124 ± 15 kJ mol-1 at T < 150 °C and 32 ± 6 kJ mol-1 at T > 150 °C. An empirical relationship between the reaction rate, the hydrogen partial pressure, the uranyl speciation, and the temperature is also proposed. This allows an estimation of the time of formation of a giant U ore deposit such as McArthur River (Canada). The duration of the mineralizing event is

  13. Zircon U-Pb ages and Sr-Nd-Hf isotopes of the highly fractionated granite with tetrad REE patterns in the Shamai tungsten deposit in eastern Inner Mongolia, China: Implications for the timing of mineralization and ore genesis

    NASA Astrophysics Data System (ADS)

    Jiang, Si-Hong; Bagas, Leon; Hu, Peng; Han, Ning; Chen, Chun-Liang; Liu, Yuan; Kang, Huan

    2016-09-01

    The Shamai tungsten deposit is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Tungsten mineralization is closely related to the emplacement of fine- to medium-grained biotite monzogranite (G1) and porphyritic biotite monzogranite (G2) in the Shamai Granite. NW-trending joints and faults host orebodies in the Shamai Granite and Devonian hornfels. The mineralization is characterized by a basal veinlet zone progressing upwards to a thick vein zone followed by a mixed zone, a veinlet zone, and a thread vein zone at the top. The ore-related alteration typically consists of muscovite, greisen, and hornfels. In order to constrain the timing of the Shamai mineralization and discuss the ore genesis, muscovite Ar-Ar, molybdenite Re-Os, and zircon U-Pb geochronological, geochemical, and Sr-Nd-Hf isotopic studies were completed on the deposit. The U-Pb zircon dating yielded weighted mean ages of 153 ± 1 Ma for G1 and 146 ± 1 Ma for G2. Muscovite from a wolframite-bearing quartz vein yielded an Ar-Ar plateau age of 140 ± 1 Ma, whereas two molybdenite samples yielded identical Re-Os model ages of 137 ± 2 Ma. These two ages are younger than the two monzogranites, suggesting a prolonged magmatic-hydrothermal interaction during tungsten mineralization. Major and trace element geochemistry shows that both G1 and G2 are characterized by high SiO2 and K2O contents, high A/CNK values (1.08-1.40), a spectacular tetrad effect in their REE distribution patterns, and non-CHARAC (charge-and-radius-controlled) trace element behavior. This suggests that both G1 and G2 are highly differentiated peraluminous rocks with strong hydrothermal interaction. The Nd-Hf isotope data for the Shamai Granite (εNd(t) between - 1.9 and + 7.4, ɛHf(t) from 5.2 to 12.8) are largely compatible with the general scenario for much of the Phanerozoic granite emplaced in the CAOB. It is here suggested that the Shamai Granite originated from partial melting of a juvenile lower crust with

  14. Zoned chromites with high Mn-contents in the Fe-Ni-Cr-laterite ore deposits from the Edessa area in Northern Greece

    NASA Astrophysics Data System (ADS)

    Michailidis, K. M.

    1990-07-01

    The mineralogy of the transported Fe-Ni-Cr-laterite ore bodies from the Edessa area in Northern Greece was studied. The special emphasis was on the textural features and chemistry of chromite. The chromite was residually inherited in laterites from weathered ultramafic rocks and it displays zonation. Three main zones were optically distinguished: an inner chromite zone, an intermediate ferritechromite zone and a magnetite rim. These three zones have distinct compositions. The major oxides MgO and Al2O3 decrease from the chromite core to the ferritechromite zone, while FeOt increases and Cr2O3 either increases or decreases. A characteristic chemical feature of the chromite is the very high Mn-content in the ferritechromite zone, up to 20%wt MnO. Chemical zonation has, however, been detected in optically unzoned chromite cores rimmed by magnetite. The zoning and the high Mn-content of the chromite is a result of serpentinization in the presence of Mn-rich fluids, following lateritic weathering and finally Alpine low-grade metamorphism.

  15. Oxidized and reduced mineral assemblages in greenstone belt rocks of the St. Ives gold camp, Western Australia: vectors to high-grade ore bodies in Archaean gold deposits?

    NASA Astrophysics Data System (ADS)

    Neumayr, Peter; Walshe, John; Hagemann, Steffen; Petersen, Klaus; Roache, Anthony; Frikken, Peter; Horn, Leo; Halley, Scott

    2008-03-01

    Hydrothermal sulfide-oxide-gold mineral assemblages in gold deposits in the Archaean St. Ives gold camp in Western Australia indicate extremely variable redox conditions during hydrothermal alteration and gold mineralization in space and time. Reduced alteration assemblages (pyrrhotite-pyrite) occur in deposits in the southwest of the camp (e.g., Argo, Junction deposits) and moderately to strongly oxidized assemblages (magnetite-pyrite, hematite-pyrite) occur in deposits in the Central Corridor in the northeast (e.g., North Orchin, Revenge deposits). Reduced mineral assemblages flank the Central Corridor of oxidized deposits and, locally, cut across it along E-W trending faults. Oxidized mineral assemblages in the Central Corridor are focused on gravity lows which are interpreted to reflect abundant felsic porphyritic intrusions at about 1,000 m below present surface. Hydrothermal magnetite predates and is synchronous with early phases of gold-associated albite-carbonate-pyrite-biotite-chlorite hydrothermal alteration. Later-stage, gold-associated pyrite is in equilibrium with hematite. The spatial distribution and temporal sequence of iron sulfides and oxides with gold indicate the presence of at least two spatially restricted but broadly synchronous hydrothermal fluids with contrasting redox states. Sulfur isotope constraints support the argument that the different mineral assemblages reflect differences in redox conditions. The δ 34S values for pyrite for the St. Ives gold camp range between -8.4‰ and +5.1‰ with the negative values occurring in oxidized magnetite-rich domains and slightly negative or positive values occurring in reduced, pyrrhotitic domains. Preliminary spatial and paragenetic analysis of the distribution of iron sulfides and oxides in the St. Ives camp suggests that gold grades are highest where the redox state of the hydrothermal alteration assemblages switches from relatively reduced pyrrhotite-pyrite to relatively oxidized magnetite

  16. Sedimentary exhalative nickel-molybdenum ores in south China

    USGS Publications Warehouse

    Lott, D.A.; Coveney, R.M.; Murowchick, J.B.; Grauch, R.I.

    1999-01-01

    Unique bedded Ni-Mo ores hosted by black shales were discovered in localized paleobasins along the Yangzte platform of southern China in 1971. Textural evidence and radiometric dates imply ore formation during sedimentation of black shales that grade into readily combustible beds, termed stone coals, which contain 10 to 15 percent organic carbon. Studies of 427 fluid inclusions indicate extreme variation in hydrothermal brine salinities that were contained by Proterozoic dolostones underlying the ore zone in Hunan and Guizhou. Variations of fluid inclusion salinities, which range from 0.1 to 21.6 wt percent NaCl equiv, are attributed to differences in the compositions of brines in strata underlying the ore bed, complicated by the presence of seawater and dilute fluids that represent condensates of vapors generated by boiling of mineralizing fluids or Cambrian meteoric water. The complex processes of ore deposition led to scattered homogenization temperatures ranging from 100??to 187??C within the Hunan ore zone and from 65??to 183??C within the Guizhou ore zone. While living organisms probably did not directly accumulate metals in situ in sufficient amounts to explain the unusually high grades of the deposits, sulfur isotope ratios indicate that bacteria, now preserved as abundant microfossils, provided sufficient sulfide for the ores by reduction of seawater sulfate. Such microbiota may have depended on vent fluids and transported organic matter for key nutrients and are consistent with a sedex origin for the ores. Vent fluids interacted with organic remains, including rounded fragments of microbial mats that were likely transported to the site of ore deposition by the action of waves and bottom currents prior to replacement by ore minerals.

  17. Invisible gold distribution on pyrite and ore-forming fluid process of the Huangshan orogenic-type gold deposit of Zhejiang, SE China: implications from mineralogy, trace elements, impurity and fluid inclusion studies

    NASA Astrophysics Data System (ADS)

    Sundarrajan, Vijay Anand; Li, Zilong; Hu, Yizhou; Fu, Xuheng; Zhu, Yuhuo

    2016-07-01

    The Huangshan orogenic-type gold deposit in Zhejiang of SE China occurred in quartz-pyrite veins. It is hosted by phyllonite that underwent greenschist-facies metamorphism along a large Jiangshan-Shaoxing tectonic belt with a NE-SW direction. Trace elemental characteristics, ore-forming process and invisible gold on different forms of pyrite and quartz are studied. The Au associated pyrite can be classified into two categories; recrystallized pyrite and euhedral pyrite. The precipitation of invisible Au on pyrite is mainly derived by Co and Ni with AuHS2 - complex in the mineralizing fluids in different events. The XPS results revealed that valence states of Au3+ replaced 2Fe2+ in the pyrite and Au0 replaced Si4+ in the quartz structure. The electron paramagnetic resonance and trace elemental results suggested that the element pairs of Ge-Li-Al in quartz and Mn-Co-Ni in pyrite have distinct impurities as identified. A fluid inclusion study showed that the auriferous quartz is characterized by low-saline and CO2-rich fluids. Coexistence of the type I-type III inclusions and same range of homogenization temperature with different mode are evidences of immiscible fluid process. The temperature-pressure values of ca. 250 °C/1250 bar and ca. 220 °C/780 bar for gold precipitation have been calculated by intersection of coexisting fluids during the entrapment. The Huangshan orogenic-type gold deposit may be associated with the Wuyi-Yunkai orogeny during the early Paleozoic, including an upper-mid greenschist-facies metamorphism (450-420 Ma). All the features suggest that the Huangshan gold deposit is probably a product linking with the early Paleozoic orogeny in South China.

  18. Dating and isotopic characteristics (Pb and S) of the Fe oxide Cu Au U REE Igarapé Bahia ore deposit, Carajás mineral province, Pará state, Brazil

    NASA Astrophysics Data System (ADS)

    Galarza, Marco Antonio; Macambira, Moacir José B.; Villas, Raimundo Netuno

    2008-05-01

    The Igarapé Bahia ore deposit is located in the Carajás mineral province, southeast of the Amazonian Craton in northern Brazil. The deposit is hosted by the Archean Igarapé Bahia Group, which consists of mafic metavolcanic, metapyroclastic, and metasedimentary rocks, in addition to banded iron-formations and hydrothermal breccias. Mafic dikes cut these lithological varieties. The Cu-Au mineralization is best developed in breccias that lie between the mafic metavolcanic and metapyroclastic/metasedimentary units. Chalcopyrite, pyrite, bornite, and chalcocite are the main sulfides and are associated with Fe-rich chlorite, magnetite, siderite, and subordinate amounts of tourmaline, fluorite, REE-bearing minerals, and calcite. Dating of chalcopyrite from the hydrothermal breccias and metavolcanic, metapyroclastic, and dike rocks by the Pb-Pb method yields ages of 2772 ± 46, 2756 ± 24, 2754 ± 36, and 2777 ± 22 Ma, respectively. A similar age of 2744 ± 12 Ma of gold from the hydrothermal breccia, mafic metavolcanic rocks, and gossan is also obtained and considered the age of the mineralization, contemporaneous with the formation of the volcanosedimentary sequences of the Igarapé Bahia Group (2745-2747 Ma). These geochronological data support a genetic link between the volcanic processes and the Igarapé Bahia Cu-Au mineralization. Pb-Pb analyses of chalcopyrite leachates from the hydrothermal breccias reveal ages of 2385 ± 122 and 2417 ± 120 Ma, which suggest remobilization, likely due to regional tectonic reactivations related to the development of the Carajás and Cinzento strike-slip fault systems. Pb isotopic analyses show highly radiogenic samples that indicate magmas derived from sources in the upper crust enriched in U and Th. δ34S values (-2.1 to +4.2) are consistent with the derivation of sulfides from magmatic fluids, but a submarine environment similar to that of Archean VMS mineralization in which evaporites have been deposited cannot be ruled out.

  19. Biodegradation of hydrocarbons and biogeochemical sulfur cycling in the salt dome environment: Inferences from sulfur isotope and organic geochemical investigations of the Bahloul Formation at the Bou Grine Zn/Pb ore deposit, Tunisia

    NASA Astrophysics Data System (ADS)

    Bechtel, A.; Shieh, Y.-N.; Pervaz, M.; Püttmann, W.

    1996-08-01

    Combined organic geochemical and stable isotope (S) analyses of samples from the Cretaceous Bahloul Formation (Tunisia) provide insight to oil accumulation processes, biogeochemical alteration of hydrocarbons, microbial sulfate reduction, and mineral deposition at the flanks of the Triassic Jebel Lorbeus diapir, forming the Bou Grine Zn/Pb deposit. The sulfur isotopic composition of the metal sulfides correlates with the degree of biodegradation of hydrocarbons, with the base-metal content and with the proportion of aromatics in the organic extracts. The δ 34S-values are interpreted to reflect bacterial sulfate reduction in a more or less closed system rather than a thermogenic contribution. The extent of H 2S production by the activity of the sulfate-reducing bacteria probably was limited by the availability of sulfate, which in turn was governed by the permeability of the respective sedimentary sequence and by the distance to the anhydrite cap rock. Evidence is provided that biodegradation of hydrocarbons and microbial sulfate reduction contribute to the formation of the high-grade mineralization inside the Bahloul Formation at the contact with the salt dome cap rock. The metals probably were derived through leaching of deeper sedimentary sequences by hot hypersaline basinal brines, evolved by dissolution of salt at the flanks of the diapirs. These hot metalliferous brines are proposed to migrate up around the diapir, finally mixing with near-surface, sulfate-rich brines in the roof zone. When the fluids came in contact with the organic-rich sediments of the Bahloul Formation, the dissolved sulfate was reduced by the sulfate-reducing bacteria. Hydrocarbons generated or accumulated in the Bahloul Formation were utilized by sulfate reducers. The occurrence of high amounts of native sulfur in high-grade ore samples suggest that the production rate of H 2S by bacterial sulfate reduction exceeded its consumption by metal-sulfide precipitation. The supply of dissolved

  20. Preliminary report on the geology of the Arbuckle and Wichita mountains, in Indian Territory and Oklahoma, with an appendix on reported ore deposits of the Wichita Mountains

    USGS Publications Warehouse

    Taff, J.A.; Bain, H.F.

    1904-01-01

    The Arbuckle Mountains consist of a moderately elevated table -land or plateau in the east-central part of the Chickasaw Nation, Indian Territory. The plateau ranges in elevation from 1,300 feet above sea, in its contracted western part, to 750 feet, at the east end, where it coalesces with the bordering plain. Geologically the Arbuckle Mountain region consists of a great thickness of rocks, composed chiefly of limestones, which range in age from middle Cambrian to Devonian, and which are succeeded on the borders by an almost equal thickness of Carboniferous conglomerates, shales, and sandstones. In the central part of the district, unconformably beneath the Cambrian strata, there is a mass of granite, granite-porphyry, diabase, and associated crystalline rocks. The uplifting and folding of the region occurred previous to the deposition of the Permian "Red Beds," which were deposited across it on the' west. The bearing of the Arbuckle uplift is approximately N. 70° W.

  1. Geologic map of Kundelan ore deposits and prospects, Zabul Province, Afghanistan; modified from the 1971 original map compilations of K.I. Litvinenko and others

    USGS Publications Warehouse

    Tucker, Robert D.; Peters, Stephen G.; Stettner, Will R.; Masonic, Linda M.; Moran, Thomas W.

    2015-10-26

    Elevations on the cross sections are derived from the original Soviet topography and may not match the Global Digital Elevation Model (GDEM) topography used on the redrafted map of this report. Most hydrography derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) has not been included on our redrafted version of the map because of a poor fit with alluvial deposits from the unmodified original Soviet map (graphical supplement no. 18; Litvinenko and others, 1971).

  2. Geochemical signatures of possible deep-seated ore deposits in Tertiary volcanic centers, Arizona and New Mexico, U.S.A.

    USGS Publications Warehouse

    Watts, K.C., Jr.; Hassemer, J.R.

    1989-01-01

    A reconnaissance geochemical survey of stream drainages within 21,000 km2 of southeastern Arizona and southwestern New Mexico shows broad zones of low-level to moderate contrast anomalies, many associated with mid-Tertiary eruptive centers and Tertiary fault zones. Of these eruptive centers, few are known to contain metallic deposits, and most of those known are minor. This, however, may be more a function of shallow erosion level than an indication of the absence of mineralization, since hydrothermal alteration and Fe-Mn-oxide staining are widespread, and geochemical anomalies are pervasive over a larger part of the region than outcrop observations would predict. Accordingly, interpretations of the geochemical data use considerations of relative erosion levels, and inferred element zonalities, to focus on possible undiscovered deposits in the subsurface of base-, precious-, and rare-metal deposits of plutonic-volcanic association. In order to enhance the identification of specific deep targets, we use the empirically determined ratio: Ag+Mn+Pb+Zn+Ba Au+Mo+Cu+Bi+W This ratio is based on reported metal contents of nonmagnetic heavy-mineral samples from the drainage sediment, determined by emission spectrographic analysis. Before the ratio was computed for each sample site, the data were normalized to a previously estimated regional threshold value. A regional isopleth map was then prepared, using a cell-averaging computer routine, with contours drawn at the 25th, 50th, 75th, 80th, 90th, 95th and 99th percentiles of the computed data. ?? 1989.

  3. The large Bystrinskoe Cu-Au-Fe deposit (Eastern Trans-Baikal Region): Russia's first example of a skarn-porphyry ore-forming system related to adakite

    NASA Astrophysics Data System (ADS)

    Kovalenker, V. A.; Abramov, S. S.; Kiseleva, G. D.; Krylova, T. L.; Yazykova, Yu. I.; Bortnikov, N. S.

    2016-06-01

    The Bystrinskoe skarn-porphyry Cu-Au-Fe deposit (Eastern Trans-Baikal Region) is confined to skarn zones, which were formed along the contact of granitoids referred to the Shakhtama intrusive complex (J2-3), with terrigenous-carbonate sedimentary rocks. Commercial (Cu-Au-Fe ± W, Mo) mineralization was formed due to the regional postcollision development involving the intrusion of porphyritic granitoids, the derivatives of oxidized adakite highly magnesian magmas enriched in water, sulfur, and metals, which could develop under melting of garnet-bearing amphibolite in the mafic lower crustal arc.

  4. Microgranular enclaves in island-arc andesites: A possible link between known epithermal Au and potential porphyry Cu-Au deposits in the Tulasu ore cluster, western Tianshan, Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaobo; Xue, Chunji; Symons, David T. A.; Zhang, Zhaochong; Wang, Honggang

    2014-05-01

    The successful exploration for porphyry copper deposit in western Tianshan, Xinjiang, faces great challenge. Tulasu basin is an important epithermal gold ore cluster in western Tianshan, which was formed in a southwest-Pacific-type island-arc setting during the late Paleozoic by the southward subduction of the North Tianshan ocean beneath the Yili plate. Porphyry Cu-Au deposits are possibly to be found at depth or adjacent to these epithermal gold deposits. Some sulfide-mineralized microgranular enclaves of monzonite porphyry and microdiorite were found in andesites of the Tawuerbieke gold district, Tulasu basin. The enclaves are randomly distributed, with generally round or subangular shape and commonly clearly defined within their host andesite, and have a chilled surrounding margin of andesite. The monzonite porphyry enclaves (MPE) exhibit porphyritic texture with the phenocrysts of plagioclase and K-feldspar. The microdiorite enclaves (MDE) are mainly composed of plagioclase and hornblende with an aplitic texture and massive structure. The host andesites show porphyritic texture, with the phenocrysts major of plagioclase, minor of hornblende and clinopyroxene. The groundmass consists of short-column plagioclase and minor clinopyroxene with a hyalopilitic texture. Zircon grains from a MPE sample yield a weighted 206Pb/238U age of 356.2 ± 4.3 Ma (n = 13, MSWD = 1.11), which is effectively coincident with the 360.5 ± 3.4 Ma (n = 20, MSWD = 0.61) of an andesite sample within analytical error, indicating that they were coeval. In addition, the MPE, MDE and the andesite samples share similar normalized incompatible element and rare earth element patterns that are characterized by a pronounced enrichment of large ion lithophile elements and a deficit of high field strength elements. Moreover, the samples show similar Nd isotope compositions to the contemporary andesites and basaltic andesites. Detailed petrology, geochronology and geochemistry studies suggest that

  5. Jurassic ash-flow sheets, calderas, and related intrusions of the Cordilleran volcanic arc in southeastern Arizona: implications for regional tectonics and ore deposits

    USGS Publications Warehouse

    Lipman, P.W.; Hagstrum, J.T.

    1992-01-01

    Volcanologic, petrologic, and paleomagnetic studies of widespread Jurassic ash-flow sheets in the Huachuca-southern Dragoon Mountains area have led to identification of four large source calderas and associated comagnetic intracaldera intrusions. Stratigraphic, facies, and contact features of the caldera-related tuffs also provide constraints on the locations, lateral displacements, and very existence for some major northwest-trending faults and inferred regional thrusts in southeastern Arizona. Silicic alkalic compositions of the Jurassic caldera-related, ash-flow tuffs; bimodal associated mafic magmatism; and interstratified coarse sedimentary deposits provide evidence for synvolcanic extension and rifting within the Cordilleran magmatic arc. Gold-copper mineralization is associated with subvolcanic intrusions at several of the Jurassic calderas. -from Authors

  6. Variations of trace element concentration of magnetite and ilmenite from the Taihe layered intrusion, Emeishan large igneous province, SW China: Implications for magmatic fractionation and origin of Fe-Ti-V oxide ore deposits

    NASA Astrophysics Data System (ADS)

    She, Yu-Wei; Song, Xie-Yan; Yu, Song-Yue; He, Hai-Long

    2015-12-01

    In situ LA-ICP-MS trace elemental analysis has been applied to magnetite and ilmenite of the Taihe layered intrusion, Emeishan large igneous province, SW China, in order to understand better fractionation processes of magma and origin of Fe-Ti-V oxide ore deposits. The periodic reversals in Mg, Ti, Mn in magnetite and Mg, Sc in ilmenite are found in the Middle Zone of the intrusion and agree with fractionation trends as recorded by olivine (Fo), plagioclase (An) and clinopyroxene (Mg#) compositions. These suggest the Taihe intrusion formed from open magma chamber processes in a magma conduit with multiple replenishments of more primitive magmas. The V and Cr of magnetite are well correlated with V and Cr of clinopyroxene indicating that they became liquidus phases almost simultaneously at an early stage of magma evolution. Ilmenite from the Middle and Upper Zones shows variable Cr, Ni, V, Mg, Nb, Ta and Sc contents indicating that ilmenite at some stratigraphic levels crystallized slightly earlier than magnetite and clinopyroxene. The early crystallization of magnetite and ilmenite is the result of the high FeOt and TiO2 contents in the parental magma. The ilmenite crystallization before magnetite in the Middle and Upper Zones can be attributed to higher TiO2 content of the magma due to the remelting of pre-existing ilmenite in a middle-level magma chamber. Compared to the coeval high-Ti basalts, the relatively low Zr, Hf, Nb and Ta contents in both magnetite and ilmenite throughout the Taihe intrusion indicate that they crystallized from Fe-Ti-(P)-rich silicate magmas. Positive correlations of Ti with Mg, Mn, Sc and Zr of magnetite, and Zr with Sc, Hf and Nb of ilmenite also suggest that magnetite and ilmenite crystallized continuously from the homogeneous silicate magma rather than an immiscible Fe-rich melt. Therefore, frequent replenishments of Fe-Ti-(P)-rich silicate magma and gravitational sorting and settling are crucial for the formation the massive and

  7. Fluid inclusion and stable isotope studies of the Mesloula Pb-Zn-Ba ore deposit, NE Algeria: Characteristics and origin of the mineralizing fluids

    NASA Astrophysics Data System (ADS)

    Laouar, Rabah; Salmi-Laouar, Sihem; Sami, Lounis; Boyce, Adrian J.; Kolli, Omar; Boutaleb, Abdelhak; Fallick, Anthony E.

    2016-09-01

    In the Saharan Atlas (NE Algeria), the Triassic evaporitic formation was brought to the surface through the thick Cretaceous and Tertiary sedimentary cover as diapirs due to the effect of Atlasic tectonic events. The diapir piercing began in the Jurassic and has continued through present day. Many outcrops of several square kilometres are distributed in a large area (approximately 80 km wide) that extends northeasterly over 300 km towards Tunisia. The diapiric evaporitic formation is often accompanied by the emplacement of Pb-Zn-Ba-F mineralization. The Mesloula massif is an example of these deposits. Fluid inclusion and sulphur, carbon and oxygen isotope studies were carried out on Pb-Zn-Ba mineralization and associated gangue carbonates. Gypsum of the Triassic formation was also analysed for its sulphur isotope composition to show the role of evaporates in the generation of this typical peridiapiric deposit. Gypsum from the Triassic formation showed a narrow range of δ34SVCDT values, ranging from +14.6 to +15.5‰ (n = 8). This range is comparable to that of Triassic seawater sulphates. Sulphide minerals yielded δ34SVCDT values between 0 and + 11.7‰ (n = 15), indicating that sulphide sulphur was likely derived from Triassic sulphates through thermochemical sulphate reduction (TSR) because fluid inclusion microthermometric measurements yielded a mean temperature of 150 °C. Residual sulphate in such a system would have been enriched in 34S; this is reflected in the barite δ34SVCDT values, which range from +21.1 to +33.5‰ (n = 5). The δ13CVPDB values of calcite minerals, ranging from +2.1 to +6.3‰ (n = 4), indicate an inorganic carbon origin, likely from the host carbonate rocks. δ18OVSMOW values were between +21.9 and + 24.9‰, indicating that the most likely source of mineralizing fluids was formation water.

  8. Uranium (U)-Tolerant Bacterial Diversity from U Ore Deposit of Domiasiat in North-East India and Its Prospective Utilisation in Bioremediation

    PubMed Central

    Kumar, Rakshak; Nongkhlaw, Macmillan; Acharya, Celin; Joshi, Santa Ram

    2013-01-01

    Uranium (U)-tolerant aerobic chemo-heterotrophic bacteria were isolated from the sub-surface soils of U-rich deposits in Domiasiat, North East India. The bacterial community explored at molecular level by amplified ribosomal DNA restriction analysis (ARDRA) resulted in 51 distinct phylotypes. Bacterial community assemblages at the U mining site with the concentration of U ranging from 20 to 100 ppm, were found to be most diverse. Representative bacteria analysed by 16S rRNA gene sequencing were affiliated to Firmicutes (51%), Gammaproteobacteria (26%), Actinobacteria (11%), Bacteroidetes (10%) and Betaproteobacteria (2%). Representative strains removed more than 90% and 53% of U from 100 μM and 2 mM uranyl nitrate solutions, respectively, at pH 3.5 within 10 min of exposure and the activity was retained until 24 h. Overall, 76% of characterized isolates possessed phosphatase enzyme and 53% had PIB-type ATPase genes. This study generated baseline information on the diverse indigenous U-tolerant bacteria which could serve as an indicator to estimate the environmental impact expected to be caused by mining in the future. Also, these natural isolates efficient in uranium binding and harbouring phosphatase enzyme and metal-transporting genes could possibly play a vital role in the bioremediation of metal-/radionuclide-contaminated environments. PMID:23080407

  9. Deep magnetic anomaly sources interpreted as Otanmäki type Iron ore reserves

    NASA Astrophysics Data System (ADS)

    Korhonen, Juha; Kukkonen, Ilmo

    2013-04-01

    In Otanmäki ore province of Central Finland vertically integrated magnetization is estimated from two aeromagnetic coverages of different altitudes and by varying overall models of regional field. Petrophysically and geochemically determined magnetization of the mined deposits and correlation between it and ore concentration is used to evaluate iron ore reserves in the deeper part of known ore fields. Further, similar analysis is made to nearby magnetically anomalous areas covered by weakly magnetic metasediments, to estimate potential ore reserves at unexposed formations.

  10. Environment of ore deposition in the Creede mining district, San Juan Mountains, Colorado; Part IV, source of fluids, from oxygen, hydrogen, and carbon isotope studies

    USGS Publications Warehouse

    Bethke, P.M.; Rye, R.O.

    1979-01-01

    The hydrogen isotopic composition of fluids responsible for formation of the near-surface silver-base metal vein deposits at Creede was measured by direct analysis of inclusion fluids in sphalerite, quartz, and rhodochrosite and was estimated from analyses of illite and chlorite. The oxygen isotopic composition was determined directly on inclusion fluids in sphalerite and was estimated from analyses of quartz, illite, rhodochrosite, siderite, and adularia. The carbon isotopic composition was estimated from analyses of rhodochrosite and siderite. The ranges in isotopic composition for water and CO2 in the fluids associated with the formation of each of the minerals is given below (number of determinations given in parentheses):Mineral delta D (sub H2) O ppm delta 18 O (sub H2) O ppm delta 13 C (sub CO2) ppmSphalerite -81 to -54 (4) -10.1 to -4.5 (4)Quartz -97 to -86 (4) -5.9 to 1.8 (18)Illite -62 to -50 (8) -1.6 to 1.2(7)Chlorite -64 to -55 (10) -2.2 to 0.8 (10)Adularia 4.2 (1)Rhodochrosite -82 to -78 (2) 4.2 to 9.4 (9) -5.7 to -4.2 (9)Siderite 4.9 to 9.9 (6) -6.9 to -2.7 (6)The delta D (sub H2) O and delta 18 O (sub H2) O values of fluids associated with the formation of sphalerite, quartz, illite/chlorite, and carbonate minerals differ substantially from one another, and these differences appear to have been maintained throughout the depositional history, regardless of the positions of the minerals in the paragenetic sequence.The data suggest that waters from three coexisting reservoirs fed the vein system alternately and episodically during vein formation, and apparently there was little mixing of the fluids from the different reservoirs. The hydrogen, oxygen, and carbon isotope data suggest that the carbonate waters were deep seated, probably dominantly magmatic, in origin. The sphalerite and illite/chlorite waters must have been dominantly meteoric in origin and substantially oxygen shifted by exchange with the volcanic country rocks. The quartz waters were

  11. 26. NORTHERN VIEW OF ORE YARD WITH ORE BRIDGES IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. NORTHERN VIEW OF ORE YARD WITH ORE BRIDGES IN THE BACKGROUND. BLAST FURNACES ALONG THE RIGHT SIDE. (Martin Stupich) - U.S. Steel Duquesne Works, Blast Furnace Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  12. 14. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE FROM THE 'GEORGE M. CAR.' VIEW LOOKING EAST. (Also see OH-18-38, OH-18-39, and OH-18-40.) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  13. 38. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE FROM THE GEORGE M. CARL.' VIEW LOOKING EAST. (Also see OH-18-14, OH-18-39, and OH-18-40) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  14. Pressure leaching las cruces copper ore

    NASA Astrophysics Data System (ADS)

    Berezowsky, R. M.; Xue, T.; Collins, M. J.; Makwana, M.; Barton-Jones, I.; Southgate, M.; Maclean, J. K.

    1999-12-01

    A hydrometallurgical process was developed for treating the Las Cruces massive sulfide-ore deposit located near Seville, Spain. A two-stage countercurrent leach process, consisting of an atmospheric leach and a pressure leach, was developed to effectively leach copper from the copper-bearing minerals and to generate a solution suitable for the subsequent solvent-extraction and copper-electrowinning operations. The results of batch and continuous miniplant tests are presented.

  15. Monzonitoid magmatism of the copper-porphyritic Lazurnoe deposit (South Primor'e): U-Pb and K-Ar geochronology and peculiarities of ore-bearing magma genesis by the data of isotopic-geochemical studies

    NASA Astrophysics Data System (ADS)

    Sakhno, V. G.; Kovalenko, S. V.; Alenicheva, A. A.

    2011-05-01

    Magmatic rocks from the copper-porphyritic Lazurnoe deposit (Central Primor'e) have been studied. It has been found that rocks from the Lazurnyi massif are referred to gabbro-monzodiorites, monzodiorites, and monzo-granodiorites formed during two magmatic phases of different ages. The earlier phase is represented by gabbro-monzodiorites and diorites of the North Stock, and the later one, by gabbro-monzodiorites and monzo-grano-diorites of the South Stock. On the basis of isotopic dating by the U-Pb (SHRIMP) method for zircon and by the K-Ar method for hornblendes and biotites, the age of magmatic rocks is determined at 110 ± 4 for the earlier phase and at 103.5 ± 1.5 for the later one. Examination of the isotopic composition for Nd, Sr, Pb, Hf, δ18O, and REE spectra has shown that melts of the first phase are contaminated with crustal rocks and they are typical for a high degree of secondary alterations. Potassiumfeldspar, biotite, propylitic alterations, and sulfidization are manifested in these rocks. The rocks of the later stage of magmatism are characteristic for a primitive composition of isotopes and the absence of secondary alterations. They carry the features of adakite specifics that allows us to consider them derivatives of mantle generation under high fluid pressure. The intrusion of fluid-saturated melts of the second phase into the magmatic source of the first phase caused both an alteration pattern of rocks and copper-porphyritic mineralization. Isotopes of sulfur and oxygen allow us to consider the ore component to be of magmatic origin.

  16. Lead isotope studies of the Guerrero composite terrane, west-central Mexico: implications for ore genesis

    NASA Astrophysics Data System (ADS)

    Potra, Adriana; Macfarlane, Andrew W.

    2014-01-01

    New thermal ionization mass spectrometry and multi-collector inductively coupled plasma mass spectrometry Pb isotope analyses of three Cenozoic ores from the La Verde porphyry copper deposit located in the Zihuatanejo-Huetamo subterrane of the Guerrero composite terrane are presented and the metal sources are evaluated. Lead isotope ratios of 3 Cenozoic ores from the El Malacate and La Esmeralda porphyry copper deposits located in the Zihuatanejo-Huetamo subterrane and of 14 ores from the Zimapan and La Negra skarn deposits from the adjoining Sierra Madre terrane are also presented to look for systematic differences in the lead isotope trends and ore metal sources among the proposed exotic tectonostratigraphic terranes of southern Mexico. Comparison among the isotopic signatures of ores from the Sierra Madre terrane and distinct subterranes of the Guerrero terrane supports the idea that there is no direct correlation between the distinct suspect terranes of Mexico and the isotopic signatures of the associated Cenozoic ores. Rather, these Pb isotope patterns are interpreted to reflect increasing crustal contribution to mantle-derived magmas as the arc advanced eastward onto a progressively thicker continental crust. The lead isotope trend observed in Cenozoic ores is not recognized in the ores from Mesozoic volcanogenic massive sulfide and sedimentary exhalative deposits. The Mesozoic ores formed prior to the amalgamation of the Guerrero composite terrane to the continental margin, which took place during the Late Cretaceous, in intraoceanic island arc and intracontinental marginal basin settings, while the Tertiary deposits formed after this event in a continental arc setting. Lead isotope ratios of the Mesozoic and Cenozoic ores appear to reflect these differences in tectonic setting of ore formation. Most Pb isotope values of ores from the La Verde deposit (206Pb/204Pb = 18.674-18.719) are less radiogenic than those of the host igneous rocks, but plot within the

  17. Sulfur isotope geochemistry of ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type ore district, Poland

    USGS Publications Warehouse

    Leach, D.L.; Vets, J.G.; Gent, C.A.

    1996-01-01

    Studies of the sulfur isotopic composition of ore and gangue minerals from the Silesian-Cracow Zn-Pb district were conducted to gain insights into processes that controlled the location and distribution of the ore deposits. Results of this study show that minerals from the Silesian-Cracow ore district have the largest range of sulfur isotope compositions in sulfides observed from any Mississippi Valley-type ore district in the world. The ??34S values for sulfide minerals range from +38 to -32 per mil for the entire paragenetic sequence but individual stages exhibit smaller ranges. There is a well developed correlation between the sulfur isotope composition and paragenetic stage of ore deposition. The first important ore stage contains mostly positive ??34S values, around 5 per mil. The second stage of ore formation are lower, with a median value of around -5 to -15 per mil, and with some values as low as -32 per mil. Late stage barite contains isotopically heavy sulfur around +32 per mil. The range in sulfur isotope compositions can be explained by contributions of sulfur from a variety of source rocks together with sulfur isotope fractionations produced by the reaction paths for sulfate reduction. Much of the variation in sulfur isotope compositions can be explained by bacterial reduction of sedimentary sulfate and disequilibrium reactions by intermediate-valency sulfur species, especially in the late-stage pyrite and sphalerite. Organic reduction of sulfate and thermal release of sulfur from coals in the Upper Silesian Coal Basin may have been important contributors to sulfur in the ore minerals. The sulfur isotopic data, ore mineral textures, and fluid inclusion data, are consistent with the hypothesis that fluid mixing was the dominant ore forming mechanism. The rather distinct lowering of ?? 34S values in sulfides from stage 2 to stage 3 is believed to reflect some fundamental change in the source of reduced sulfur and/or hydrology of the ore

  18. Summary of the mineralogy of the Colorado Plateau uranium ores

    USGS Publications Warehouse

    Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.

    1956-01-01

    In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little

  19. Geology of the manganese deposits of Cuba

    USGS Publications Warehouse

    Simons, Frank S.; Straczek, John A.

    1958-01-01

    Deposits of manganese ore have been found in five of the six provinces of Cuba and have been reported from the sixth.  Only Oriente and Pinar del Rio provinces have more than a few known deposits and only the deposits of Oriente have yielded any appreciable amount of ore.

  20. ORE CONVEYANCE SYSTEM AND ADIT. LOOKING WEST. ORE FROM THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ORE CONVEYANCE SYSTEM AND ADIT. LOOKING WEST. ORE FROM THE MINES ABOVE AT THE RIDGELINE AND TO THE RIGHT WAS CONVEYED TO THIS AREA AND DUMPED INTO THE SHAFT AT CENTER. THIS SHAFT OPENS INTO THE ADIT AT BOTTOM CENTER. THERE IS ANOTHER SHAFT OPENING INTO THE ADIT JUST ABOVE THE ADIT BEHIND THE STONE WALL. THE ORE WAS LOADED INTO TRAM CARS INSIDE THE ADIT AND CONVEYED ON TRACKS TO THE TRESTLE LEADING TO THE PRIMARY ORE BIN AT THE TRAM TERMINAL. TRACKS CAN BE SEEN LEADING FROM THE ADIT AND TO THE LEFT. THE ORE WAS THEN DUMPED INTO A CHUTE AT THE END OF THE TRESTLE CARRYING IT INTO THE ORE BIN AT THE TRAM TERMINAL(SEE CHUTE ON CA-291-30). - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

  1. Exploration for uranium deposits in the Spring Creek Mesa area, Montrose County, Colorado

    USGS Publications Warehouse

    Roach, Carl Houston

    1954-01-01

    4. The “ore-bearing sandstone” in the vicinity of relatively unoxidized ore deposits commonly contains sparse to abundant disseminated pyrite. In the vicinity of oxidized deposits it commonly contains abundant limonite spots and widespread limonite staining.

  2. Gold in the Brunswick No. 12 volcanogenic massive sulfide deposit, Bathurst Mining Camp, Canada: Evidence from bulk ore analysis and laser ablation ICP-MS data on sulfide phases

    NASA Astrophysics Data System (ADS)

    McClenaghan, Sean H.; Lentz, David R.; Martin, Jillian; Diegor, Wilfredo G.

    2009-07-01

    The 329-Mt Brunswick No. 12 volcanogenic massive sulfide deposit (total resource of 163 Mt at 10.4% Zn, 4.2% Pb, 0.34% Cu, and 115 g/t Ag) is hosted within a Middle Ordovician bimodal volcanic and sedimentary sequence. Massive sulfides are for the most part syngenetic, and the bulk of the sulfide ore occurs as a Zn-Pb-rich banded sulfide facies that forms an intimate relationship with a laterally extensive Algoma-type iron formation and defines the Brunswick Horizon. Zone refining of stratiform sulfides is considered to have resulted in the development of a large replacement-style Cu-rich basal sulfide facies, which is generally confined between the banded sulfide facies and an underlying stringer sulfide zone. Complex polyphase deformation and associated lower- to upper-greenschist facies regional metamorphism is responsible for the present geometry of the deposit. Textural modification has resulted in a general increase in grain size through the development of pyrite and arsenopyrite porphyroblasts, which tend to overprint primary mineral assemblages. Despite the heterogeneous ductile deformation, primary features have locally been preserved, such as fine-grained colloform pyrite and base and precious metal zonation within the Main Zone. Base metal and trace element abundances in massive sulfides from the Brunswick No. 12 deposit indicate two distinct geochemical associations. The basal sulfide facies, characterized by a proximal high-temperature hydrothermal signature (Cu-Co-Bi-Se), contains generally low Au contents averaging 0.39 ppm ( n = 34). Conversely, Au is enriched in the banded sulfide facies, averaging 1.1 ppm Au ( n = 21), and is associated with an exhalative suite of elements (Zn-Pb-As-Sb-Ag-Sn). Finely laminated sulfide lenses hosted by iron formation at the north end of the Main Zone are further enriched in Au, averaging 1.7 ppm ( n = 41) and ranging up to 8.2 ppm. Laser ablation inductively coupled plasma-mass spectrometry (ICP-MS) analyses of

  3. Silicophosphate Sorbents, Based on Ore-Processing Plants' Waste in Kazakhstan

    ERIC Educational Resources Information Center

    Kubekova, Sholpan N.; Kapralova, Viktoria I.; Telkov, Shamil A.

    2016-01-01

    The problem of ore-processing plants' waste and man-made mineral formations (MMF) disposal is very important for the Republic of Kazakhstan. The research of various ore types (gold, polymetallic, iron-bearing) MMF from a number of Kazakhstan's deposits using a complex physical and chemical methods showed, that the waste's main components are…

  4. New isotopic evidence bearing on bonanza (Au-Ag) epithermal ore-forming processes

    NASA Astrophysics Data System (ADS)

    Saunders, James A.; Mathur, Ryan; Kamenov, George D.; Shimizu, Toru; Brueseke, Matthew E.

    2016-01-01

    New Cu, S, and Pb isotope data provide evidence for a magmatic source of metal(loid)s and sulfur in epithermal Au-Ag deposits even though their ore-forming solutions are composed primarily of heated meteoric (ground) waters. The apparent isotopic discrepancy between ore metals and ore-forming solutions, and even between the ore and associated gangue minerals, indicates two different sources of epithermal ore-forming constituents: (1) a shallow geothermal system that not only provides the bulk of water for the ore-forming solutions but also major chemical constituents leached from host rocks (silica, aluminum, potassium, sodium, calcium) to make gangue minerals and (2) metals and metalloids (As, Te, Sb, etc.) and sulfur (±Se) derived from deeper magma bodies. Isotopic data are consistent with either vapor-phase transport of metal(loids) and sulfur and their subsequent absorption by shallow geothermal waters or formation of metallic (Au, Ag, Cu phases) nanoparticles at depth from magmatic fluids prior to encountering the geothermal system. The latter is most consistent with ore textures that indicate physical transport and aggregation of nanoparticles were significant ore-forming processes. The recognition that epithermal Au-Ag ores form in tectonic settings that produce magmas capable of releasing metal-rich fluids necessary to form these deposits can refine exploration strategies that previously often have focused on locating fossil geothermal systems.

  5. Can I Trust ORE Reports?

    ERIC Educational Resources Information Center

    Feedback, 1984

    1984-01-01

    This issue of FEEDBACK, a newsletter produced by the the Austin Independent School District Office of Research and Evaluation (ORE), illustrates the accuracy, validity, and fairness of ORE reports. The independence of the reports is explained. Internal and external quality controls are used to ensure reliability and accuracy of the reports.…

  6. A geochemical assessment of possible lunar ore formation

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.; Colson, Russell O.; Vaniman, David

    1991-01-01

    The Moon apparently formed without appreciable water or other relatively volatile materials. Interior concentrations of water or other volatile substances appear to be extremely low. On Earth, water is important to the genesis of nearly all types of ores. Thus, some have reasoned that only abundant elements would occur in ore concentrations. The definition and recognition of ores on the Moon challenge the imaginations and the terrestrial perceptions of ore bodies. Lunar ores included solar-wind soaked soils, which contain abundant but dilute H, C, N, and noble gases (including He-3). Oxygen must be mined; soils contain approximately 45 percent (wt). Mainstream processes of rock formation concentrated Si, Mg, Al, Fe, and Ca, and possibly Ti and Cr. The highland surface contains approximately 70 percent (wt) feldspar (mainly CaAl2Si2O8), which can be separated from some highland soils. Small fragments of dunite were collected; dunite may occur in walls and central peaks of some craters. Theoretical extensions of observations of lunar samples suggest that the Moon may have produced ores of trace elements. Some small fragments have trace-element concentrations 10(exp 4) times higher than the lunar average, indicating that effective geochemical separations occurred; processes included fractional crystallization, silicate immiscibility, vaporization and condensation, and sulfide metamorphism. Operations of these processes acting on indigenous materials and on meteoritic material in the regolith could have produced ores. Infalling carbonaceous meteorites and comets have added water and hydrocarbons that may have been cold-trapped. Vesicles in basalts, pyroclastic beads, and reported transient events suggest gag emission from the lunar interior; such gas might concentrate and transport rare elements. Large impacts may disperse ores or produce them through deposition of heat at depth and by vaporization and subsequent condensation. The main problem in assessing lunar

  7. Ore body shapes versus regional deformation patterns as a base for 3D prospectivity mapping in the Skellefte Mining District, Sweden

    NASA Astrophysics Data System (ADS)

    Bauer, T.; Skyttä, P.; Hermansson, T.; Weihed, P.

    2012-04-01

    The current work in progress is based on detailed structural analysis carried out during the last years, which unravels the crustal evolution of the ore bearing Palaeoproterozoic Skellefte District in northern Sweden. The shape and orientation of the volcanic-hosted massive sulfide (VMS) ore bodies through the district is modeled in three dimensions and reflected against the regional deformation patterns. By doing this we aim to understand the coupling between the transposition of the ore bodies and the deformation structures in the host rocks, honoring both local deformation features and regional structural transitions. The VMS ore bodies are modeled in gOcad (Paradigm) visualizing both the strike and dip of the ore lenses as well as their dimensions. 25 deposits are currently available in 3D and modelling of the remaining 55 deposits is planned or partly in progress. The ore deposits and mineralizations are classified according to their shape and size. The complexly deformed ore bodies are described each independently. Subsequently, the VMS deposits are plotted on the structural map of the Skellefte district displaying their size and strike, dip and plunge values in order to show their spatial distribution and their relationship with shear zones. The preliminary results show a good correlation between the shape and orientation of the ore bodies and the related structures. Plotting the VMS deposits on a structural map clearly demonstrates the close spatial relation of the ore deposits and regional scale shear zones. Furthermore, the deformation style within the ore deposits generally mimics the deformation style of the shear zones, e.g. the plunge of elongate ore bodies parallels the mineral lineation of the related shear zone. Based on these results, the location and shape of ore deposits may be estimated, which is an important tool for prospectivity mapping and near mine exploration of ore districts.

  8. Oil field brines as ore-forming solutions

    SciTech Connect

    Sverjensky, D.A.

    1984-01-01

    The hypothesis that oil field brines can become ore-forming solutions and can transport base metals and reduced sulfur to sites of ore formation by large-scale migration along aquifers out of sedimentary basins is examined using data on the chemical compositions of presnt-day heavy metal-bearing oil field brines and the petrography of their reservoir rocks, and is a theoretical evaluation of the chemistry of possible water-rock interactions in the aquifers during migration. The concept of water-rock interactions in the aquifers of sandstone and carbonate-hosted base metal sulfide ore deposits is clearly of potential importance in explaining geochemical characteristics of such deposits, including the Na/K ratios of the fluid inclusions, the lead isotope compositions of galena, the paragenesis sphalerite followed by galena, and the overall Zn/Pb ratios of the deposits. It is because of these water-rock interactions that a single brine carrying base metals and reduced sulfur can evolve chemically in its aquifer so that brines with a spectrum of geochemical characteristics arrive as a function of time at a distant site of ore formation.

  9. Reinforcement core facilitates O-ring installation

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Reinforcement core holds O-ring in place within a structure while adjacent parts are being assembled. The core in the O-ring adds circumferential rigidity to the O-ring material. This inner core does not appreciably affect the sectional elasticity or gland-sealing characteristics of the O-ring.

  10. Krasnotur'insk Skarn copper ore field, Northern Urals: The U-Pb age of ore-controlling diorites and their place in the regional metallogeny

    NASA Astrophysics Data System (ADS)

    Grabezhev, A. I.; Ronkin, Yu. L.; Puchkov, V. N.; Gerdes, A.; Rovnushkin, M. Yu.

    2014-06-01

    The Krasnotur'insk skarn copper ore field known from the theoretical works of Academician K.S. Korzhinskii is located in the western part of the Tagil volcanic zone (in the area of the town of Krasnotur'insk). The ore field is composed of layered Devonian (Emsian) volcanosedimentary rocks intruded by small plutons of quartz diorites, diorites, and gabbrodiorites. Widespread pre-ore and intra-ore dikes of similar composition control the abundance of the andradite skarns formed after limestones and the magnetitesulfide and sulfide ore bodies formed after skarns. The LA-ICP-MS U-Pb concordant age of zircon from the quartz diorite of the Vasil'evsko-Moskalevskii pluton calculated by 16 analyses (16 crystals) is 407.7 ± 1.6 Ma (MSWD = 1.5). Taking into account the geological and petrogeochemical similarity of diorites of small plutons and intra-ore dikes, it is assumed that this age corresponds to the period of formation of the ore-magmatic system of the Krasnotur'insk skarn copper ore field. It was probably formed somewhat earlier than the Auerbakh montzonitic pluton and the accompanying skarn magnetite deposits in the south.

  11. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

    1989-11-14

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

  12. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, Michael R.; Arnold, Robert G.; Stephanopoulos, Gregory

    1989-01-01

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

  13. Mineralogy and ore textures at the Iron Mountain mine, St. Francois County, Missouri

    SciTech Connect

    Dudley, M.A.; Hagni, R.D. )

    1993-03-01

    The Iron Mountain mine, located in the St. Francois Mountains of southeast Missouri, approximately 80 miles southwest of St. Louis, Missouri, has been the third largest iron producer in Missouri. It is one of six known major iron deposits in the Southeast Missouri Iron Metallogenic Province. The deposit is in the form of a unique inverted cup-shaped body, and it is hosted by volcanic flows of Middle Proterozoic age. The iron mineralization occurred during Precambrian time as shown by the presence of pebbles of iron ore in the overlying Cambrian sediments. A study has been initiated based on drill core samples and data donated to the Missouri Geological Survey. Drill cores from more than 1,000 exploratory holes are available. Core samples from selected drill holes are being studied using various analytical, petrographic, ore microscopic, and geochemical methods. Hematite and, to a lesser extent, magnetite are the main ore minerals. The most abundant gangue minerals are andradite, quartz, calcite, actinolite, apatite, epidote, and chlorite. The ore occurs in two modes: massive veins and as matrix between brecciated host rock. Some of the veins exhibit crustiform ore and gangue mineral textures. Host rock alteration is uncommon, and in most places the contact with the ore is quite sharp. The objectives of this study are to examine the ore and gangue mineralogy, determine the causes of brecciation, utilize ore textural information to evaluate the relative roles of hydrothermal and magmatic processes in the origin of the deposit, and explore the relationships between the Iron Mountain deposit and, other iron deposits in Missouri, and assess how the deposit fits in with the Olympic Dam model.

  14. The mechanism of formation of the seafloor massive sulfide ore body beneath the seafloor at HAKUREI Site in Izena Caldera, Middle Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Yoshizumi, R.; Urabe, T.

    2012-12-01

    The first seafloor hydrothermal activity in northwest Pacific was found at the northeastern rim of the Izena Caldera (Jade Site), Middle Okinawa Trough in 1988 (Halbach et al.,1989). The tectonic setting of the sulfide occurrence, even though small in amount, is similar to that of Kuroko deposits which are the volcanogenic massive sulfide (VMS) deposits found in volcano-sedimentary units in northern Japan. Later, large seafloor massive sulfide (SMS) ore bodies were discovered above and beneath the seafloor in the central part of the Izena Caldera (HAKUREI Site). The ore reserve is estimated to be 5million tons based on some 100 short (<20 meters), dense drillings (Japan Oil, Gas and Metals National Corporation (JOGMEC), 2011), and is regarded as the biggest "proven" SMS deposit in the world. It is worthy to note that the HAKUREI ore deposit can be divided into Ore A (Upper ore bodies) and the Ore B (Lower ore bodies) which are separated by silt and pumice-rich sedimentary layer of a few meter in thickness. The Upper ore bodies are composed of sulfide "mounds" and "chimneys", which are commonly observed in hydrothermal areas. However, the nature of the Lower ore bodies remain uninvestigated. We conducted two research cruises at the HAKUREI site in 2011: TAIGA11 cruise of Exploration Vessel Hakurei-Maru NO.2 (JOGMEC) with Benthic Multicoreing System (BMS) and NT11-15 cruise of R/V Natshushima with ROV Hyper Dolphin (JAMSTEC). In the former cruise, a core (H-1) 5.4m in length was drilled to intersect both the Upper and Lower ore bodies which are separated by sediment using BMS. While, in latter cruise, volcanic rocks (aphyric rhyolite) and sulfide ores (Upper ore) were collected using Hyper Dolphin. The obtained sulfide ores were served for examination with the ore microscopy, electron probe microanalyzer (EPMA) and heating stage for fluid inclusions in barite in ore. Sphalerite and galena dominate at upper part of the Lower ore, while chalcopyrite and covellite

  15. Ore distribution in the Herminia mine (Julcani, Peru): ore bands and role ore shoots

    SciTech Connect

    Petersen, U.; Murdock, G.

    1985-01-01

    Julcani has been one of the major silver and bismuth producing districts of Peru during the past 30 years. The veins are related to a late Miocene volcanic complex and the ore minerals are mainly enargite, tetrahedrite, various silver sulfosalts and galena; gangue minerals are mostly pyrite and barite. Extensive mining, good accessibility and excellent record keeping provide a good opportunity to study ore distribution patterns and zoning in the Herminia mine. Six veins were selected because of their abundant information and coverage of the zoning sequence. The inner copper, intermediate silver and outer lead grade maxima are shown to form parallel ore bands that are generally concordant with the previously reported metal ratio contours, despite the different ages of the ore minerals. These systematic relations are corroborated by logarithmic covariation diagrams. Ore bands join at vein junctions, demonstrating that the vein network constituted a connected hydrothermal system. Oreshoots form at ore band lobes that are related to greater vein widths. Grade and ratio contours indicate that solution flow was generally horizontal to the SW within a favorable volcanic horizon in the 420-580 level range. Several exploration and development applications are illustrated.

  16. Partial Melting of Massive Sulfide Ore Bodies During Metamorphism

    NASA Astrophysics Data System (ADS)

    Frost, B. R.

    2004-05-01

    Sulfide systems with the major metals Cu, Ni, Fe, Pb, and Zn show only limited field for melt at temperatures typical of most regional metamorphism (T<700oC). However, the presence of minor metals such as As, Hg, Sb, Tl, Se, and Te may flux melting down to much lower T. For example at one bar the eutectic between realgar and orpiment lies at 281oC. This means that numerous sulfosalt assemblages may melt at conditions well within those of regional metamorphism. Most massive sulfide ore bodies metamorphosed at greenschist or lower amphibolite facies contain rather simple assemblages of pyrite, pyrrhotite, chalcopyrite, sphalerite ± galena. In contrast, sulfide ore deposits metamorphosed at higher grades contain the same minerals along with a complex assortment of minor phases, including sulfosalts, native metals, and alloys, many of which are enriched in Au and Ag. We contend that these complex assemblages, which are enriched in low-melting metals, were formed during crystallization of a polymetallic melt. For the assemblages commonly found in massive sulfide deposits the most likely melt-forming reaction is arsenopyrite + pyrite = pyrrhotite + melt. At 1 bar this reaction takes place at 491oC; melting temperature increases by 17oC/kilobar. In our model the melt is initially rich in As and S (and perhaps Hg, Sb, Tl, Se, and Te). Au and Ag will also be fractionated into the melt. With increasing temperature the polymetallic melt will accommodate increasing amounts of Pb, Cu, and then Fe and Zn. The ore bodies from highest metamorphic terranes are commonly associated with rims of Mn- and Ca-pyroxenoids, suggesting that at the highest grades of metamorphism polymetallic melts may accommodate considerable amounts of these normally lithophile elements. We have identified more than 25 ore deposits from around the world where the ore partially melted during metamorphism. These include Cu-Fe-Zn deposits (mostly VMS), Pb-Zn deposits (both MVT and SEDEX), and disseminated Au

  17. The evolution of the earth's crust and of ore-formation processes

    NASA Astrophysics Data System (ADS)

    Tugarinov, A. I.

    Special attention is given to various aspects of the Precambrian geochronology of various regions. A geochronological scale of the Precambrian is discussed, noting that correlations between continents that have been carried out with this scale are recognized internationally. Attention is also given to various problems concerning the evolution of the crust during the earth's geological history. Studies on the formation of ore deposits are included which deal not only with the origin of the ore but also with determining the exact physicochemical parameters of the ore-formation process.

  18. Geology of the pitchblende ores of Colorado

    USGS Publications Warehouse

    Bastin, Edson S.

    1915-01-01

    The large amount of public interest that has recently been manifested in radium because of the apparent cures of cancer effected by certain of its emanations makes it desirable to place before the public as promptly as possible all available information in regard to the occurrence of the minerals from which radium may be derived. The following account of the mode of occurrence of pitchblende at Quartz Hill, in Gilpin County, Colo., is therefore published in advance of a much larger report on the same region in which many other types of ore deposits will be considered. The field studies were made.in the fall of 1912. As the geologic relations at Quartz Hill differ in important particulars from those at foreign localities, a summary of the genetically important features of the principal European occurrences is included for purposes of comparison.

  19. SRB O-ring free response analysis

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1986-01-01

    The free response of viton O-rings were investigated. Two different response mechanisms of viton O-rings are identified and a theoretical representation of the two mechanisms is compared with experimental results for various temperatures.

  20. Measuring Gaps In O-Ring Seals

    NASA Technical Reports Server (NTRS)

    Johnson, Scott E.

    1990-01-01

    Technique enables measurement of leakage areas created by small obstructions in O-ring seals. With simple fixture, gaps measured directly. Compresses piece of O-ring by amount determined by spacers. Camera aimed through clear plastic top plate records depression made in O-ring by obstruction. Faster, easier, more accurate than conventional estimation.

  1. O-ring gasket test fixture

    NASA Technical Reports Server (NTRS)

    Turner, James Eric (Inventor); Mccluney, Donald Scott (Inventor)

    1991-01-01

    An apparatus is presented for testing O-ring gaskets under a variety of temperature, pressure, and dynamic loading conditions. Specifically, this apparatus has the ability to simulate a dynamic loading condition where the sealing surface in contact with the O-ring moves both away from and axially along the face of the O-ring.

  2. Conical O-ring seal

    DOEpatents

    Chalfant, Jr., Gordon G.

    1984-01-01

    A shipping container for radioactive or other hazardous materials which has a conical-shaped closure containing grooves in the conical surface thereof and an O-ring seal incorporated in each of such grooves. The closure and seal provide a much stronger, tighter and compact containment than with a conventional flanged joint.

  3. Conical O-ring seal

    DOEpatents

    Chalfant, G.G. Jr.

    A shipping container for radioactive or other hazardous materials has a conical-shaped closure containing grooves in the conical surface thereof and an O-ring seal incorporated in each of such grooves. The closure and seal provide a much stronger, tighter and compact containment than with a conventional flanged joint.

  4. Gaseous reduction of laterite ores

    NASA Astrophysics Data System (ADS)

    Utigard, T.; Bergman, R. A.

    1993-04-01

    Lateritic nickel ores have been reduced under laboratory conditions. The reduction experiments were carried out at temperatures from 500 °C to 1100 °C in a horizontal tube furnace using various mixtures of H2 and CO2. The hydrogen evolution method was used to measure the degree of metallization of the reduced ore. It was found that the rate of reduction was very low at 500 °C but then increased rapidly upon heating the ore to 600 °C. The percent metallics increased with increasing H2 to CO2 ratios in the reducing gas. At temperatures between 600 °C and 1100 °C, a H2 to CO2 ratio of 3 leads to the formation of 5 to 6 pct metallics in the reduced calcine was shown. Heating the ore in air or nitrogen prior to reduction does not affect the degree of metallization. A H2 to CO2 ratio of at least 4 is required to obtain a ferronickel product analyzing 36 pct nickel if no further reduction is carried out during the subsequent smelting operation.

  5. Osmium isotope constraints on ore metal recycling in subduction zones

    PubMed

    McInnes; McBride; Evans; Lambert; Andrew

    1999-10-15

    Veined peridotite xenoliths from the mantle beneath the giant Ladolam gold deposit on Lihir Island, Papua New Guinea, are 2 to 800 times more enriched in copper, gold, platinum, and palladium than surrounding depleted arc mantle. Gold ores have osmium isotope compositions similar to those of the underlying subduction-modified mantle peridotite source region, indicating that the primary origin of the metals was the mantle. Because the mantle is relatively depleted in gold, copper, and palladium, tectonic processes that enhance the advective transport and concentration of these fluid soluble metals may be a prerequisite for generating porphyry-epithermal copper-gold deposits. PMID:10521343

  6. Osmium isotope constraints on ore metal recycling in subduction zones

    PubMed

    McInnes; McBride; Evans; Lambert; Andrew

    1999-10-15

    Veined peridotite xenoliths from the mantle beneath the giant Ladolam gold deposit on Lihir Island, Papua New Guinea, are 2 to 800 times more enriched in copper, gold, platinum, and palladium than surrounding depleted arc mantle. Gold ores have osmium isotope compositions similar to those of the underlying subduction-modified mantle peridotite source region, indicating that the primary origin of the metals was the mantle. Because the mantle is relatively depleted in gold, copper, and palladium, tectonic processes that enhance the advective transport and concentration of these fluid soluble metals may be a prerequisite for generating porphyry-epithermal copper-gold deposits.

  7. Origin of the granites and related Sn and Pb-Zn polymetallic ore deposits in the Pengshan district, Jiangxi Province, South China: constraints from geochronology, geochemistry, mineral chemistry, and Sr-Nd-Hf-Pb-S isotopes

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Jiang, Shao-Yong; Luo, Lan; Zhao, Kui-Dong; Ma, Liang

    2016-05-01

    The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129-128 Ma), which is in good agreement with the U-Pb dating (130-128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8-13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1-13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show

  8. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-09-30

    Heap leaching is one of the methods being used to recover metal from low grade ore deposits. The main problem faced during heap leaching is the migration of fine grained particles through the heap, forming impermeable beds which result in poor solution flow. The poor solution flow leads to less contact between the leach solution and the ore, resulting in low recovery rates. Agglomeration of ore into coarse, porous masses prevents fine particles from migrating and clogging the spaces and channels between the larger ore particles. Currently, there is one facility in the United States which uses agglomeration. This operation agglomerates their ore using leach solution (raffinate), but is still experiencing undesirable metal recovery from the heaps due to agglomerate breakdown. The use of a binder, in addition to the leach solution, during agglomeration would help to produce stronger agglomerates that did not break down during processing. However, there are no known binders that will work satisfactorily in the acidic environment of a heap, at a reasonable cost. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. Increasing copper recovery in heap leaching by the use of binders and agglomeration would result in a significant decrease in the amount of energy consumed. Assuming that 70% of all the leaching heaps would convert to using agglomeration technology, as much as 1.64*10{sup 12} BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, which is equivalent to saving approximately 18% of the energy currently being used in leaching heaps. For every week a leach cycle was decreased, a savings of as much as 1.23*10{sup 11} BTU per week would result. This project has identified several acid-resistant binders and agglomeration procedures. These binders and experimental procedures will be able to be used for use in improving the energy efficiency of

  9. Composition and origin of Early Cambrian Tiantaishan phosphorite-Mn carbonate ores, Shaanxi Province, China

    USGS Publications Warehouse

    Hein, J.R.; Fan, D.; Ye, J.; Liu, T.; Yeh, H.-W.

    1999-01-01

    The Tiantaishan phosphorite-Mn carbonate ores occur in the Early Cambrian Tananpo Formation in complexly folded and faulted rocks located in southern Shaanxi Province. About 65 x 106 tonnes of 17% P2O5 ore reserves exist and Mn-ore reserves are about 8.3 x 106 tonnes of +18% Mn. The stratigraphic sequence in ascending order consists of black phyllite, black to gray phosphorite ore, black phyllite, rhodochrostone ore, Mn mixed-carbonates, and dolostone. Data are presented from microprobe mineral chemistry, whole-rock chemistry, stable isotopes of carbonates, X-ray mineralogy, petrographic and SEM observations, and statistical analysis of chemical data. The dominant ore-forming minerals are hydroxy- and carbonate fluorapatite and Ca rhodochrosite, with Mg kutnahorite and dolomite comprising the Mn mixed-carbonate section. Pyrite occurs in all rock types and alabandite (MnS) occurs throughout the rhodochrostone section. The mean P2O5 content of phosphorite is 31% and argillaceous phosphorite is 16%, while the mean MnO content of rhodochrostone ore is 37%. Phosphorite ores are massive, spheroidal, laminated, and banded, while rhodochrostone ores have oolitic, spheroidal, and granular fabrics. The most distinguishing characteristics of the ores are high total organic carbon (TOC) contents (mean 8.4%) in the phosphorite and high P2O5 contents (mean 2.7%) in the rhodochrostone ore. The atypically high TOC contents in the Tiantaishan phosphorite probably result from very strong productivity leading to high sedimentation rates accompanied by weak reworking of sediments; poor utilization of the organic matter by bacteria; and/or partial replacement of bacterial or algal mats by the apatite. The depositional setting of the ores was the margin of an epicontinental seaway created as a direct consequence of global processes that included break-up of a supercontinent, formation of narrow seaways, creation of extensive continental shelves, overturn of stagnant, metal-rich deep

  10. Modeling the formation of porphyry-copper ores

    USGS Publications Warehouse

    Ingebritsen, Steven E.

    2012-01-01

    Porphyry-copper ore systems, the source of much of the world's copper and molybdenum, form when metal-bearing fluids are expelled from shallow, degassing magmas. On page 1613 of this issue, Weis et al. (1) demonstrate that self-organizing processes focus metal deposition. Specifically, their simulation studies indicate that ores develop as consequences of dynamic variations in rock permeability driven by injection of volatile species from rising magmas. Scenarios with a static permeability structure could not reproduce key field observations, whereas dynamic permeability responses to magmatic-fluid injection localized a metal-precipitation front where enrichment by a factor of 103 could be achieved [for an overview of their numerical-simulation model CSMP++, see (2)].

  11. Using tailings from the enrichment of zircon-ilmenite ores

    SciTech Connect

    Suleimenov, S.T.; Saibulatov, S.Zh.; Togzhanov, I.A.; Suleimenov, K.T.; Abdrakhimov, V.Z.; Vasil'chenko, N.A.

    1988-07-01

    X-ray methods, IR-spectroscopy, and microscopic techniques were used to investigate the phase inversions occurring during the firing of the clay part of the tailings from the gravitation enrichment of zircon-ilmenite ores from the Karotkel'sk deposit to evaluate the wastes as ceramic raw materials. Results showed the development of a liquid phase at a temperature below 950 C, intense crystallization of mullite at 1000-1050 C, the formation of a solid solution of the substitution type, replacing the mullite by oxides of iron and titanium, and the polymorphic inversion of beta-quartz to alpha-cristobalate. The properties of facing tiles from (%) 50 clay part of the KhGR ores, 30 light fraction ash and 20 wollastonite are shown and compared with the properties of tiles made from factory bodies of the Tselinogradsk ceramic combine.

  12. Softened-Stainless-Steel O-Rings

    NASA Technical Reports Server (NTRS)

    Marquis, G. A.; Waters, William I.

    1993-01-01

    In fabrication of O-ring of new type, tube of 304 stainless steel bent around mandril into circle and welded closed into ring. Ring annealed in furnace to make it soft and highly ductile. In this condition, used as crushable, deformable O-ring seal. O-ring replacements used in variety of atmospheres and temperatures, relatively inexpensive, fabricated with minimum amount of work, amenable to one-of-a-kind production, reusable, and environmentally benign.

  13. Metallization of siderite ore in reducing roasting

    NASA Astrophysics Data System (ADS)

    Vusikhis, A. S.; Leont'ev, L. I.; Kudinov, D. Z.; Gulyakov, V. S.

    2016-05-01

    The behavior of the initial ore and the concentrate of magnetoroasting beneficiation during metallization under the conditions that are close to those for reducing roasting of iron ores in a rotary furnace is studied in terms of works on extending the field of application of Bakal siderites. A difference in the mechanisms of the metallization of crude ore and the roasted concentrate is observed. The metallization of roasted concentrate lumps is more efficient than that of crude siderite ore. In this case, the process ends earlier and can be carried out at higher temperatures (1250-1300°C) without danger of skull formation.

  14. Two types of ore-bearing mafic complexes of the Early Proterozoic East-Scandinavian LIP and their ore potential

    NASA Astrophysics Data System (ADS)

    Mitrofanov, Felix; Zhirov, Dmitry; Bayanova, Tamara; Korchagin, Alexey; Chaschin, Victor

    2015-04-01

    Two types of the ore-bearing mafic complexes are allotted in the East-Scandinavian large igneous province (LIP). They differ in geodynamic setting, structure, isotope geochemistry, petrology and mineralogy. The PGE-bearing mafic-ultramafic layered intrusions are associated with the first complex. They have been formed at an initial (pre-rift) stage of LIP. Features of origin of this complex are: 1) large-scale, protracted, and multiple episodes of deep mantle plume or asthenosphere upwelling; 2) the vast non-subduction-type basaltic magma in an intraplate continental setting; 3) low-sulfide Pt-Pd (with Ni, Cu, Au, Co and Rh) mineralization in different geological setting (reef- and contact type etc.); 4) anomalously high concentrations of PGEs in the bulk sulfides, inferred platinum distribution coefficient between silicate and sulfide melts of >100000. Deep mantle magma source is enriched in ore components (fertile source) and lithophile elements. It is reflected in the isotope indicators such as ɛNd(T) from -1 to -3, ISr(87Sr/86Sr) from 0.702 to 0.704, 3Не/4Не = (10 ^-5 ÷ 10 ^-6). Magma and ore sources differ from those of Mid-Ocean Ridge basalts (MORB), subduction-related magma but are similar to EM-I. Ore-bearing mafic complexes formed during a long period of time and by different episodes (2490±10 Ma; 2470±10 Ma; 2450±10 Ma; 2400±10 Ma), and by mixing between the boninitic an anorthositic magmas. It is known about 10 deposits and occurrences in Kola region with total reserves and resources about 2000 tons in palladium equivalent (with an average content ≥2-3 ppm). Intrusions with the rich sulfide Ni-Cu ore (with Co and poor PGE) are associated with the second mafic complex. Ore-controlling mafic-ultramafic intrusions are formed at a final stage of the intracontinental rifting of the Transitional period (2200-1980 Ma). Initial magma is depleted and similar to the MORB in terms of rare earths distribution. Enriched ferropicritic Fe-Ti derivatives of

  15. Evolutionary and geological factors controlling endogenic uranium mineralization and the potential for the discovery of new ore districts

    NASA Astrophysics Data System (ADS)

    Mashkovtsev, G. A.; Miguta, A. K.; Shchetochkin, V. N.

    2015-03-01

    The exhaustion of known surface and near-surface high-grade uranium deposits poses the serious problem of prospecting and exploration of new large endogenic deposits. A comparison of large data sets for endogenic deposits from the world's major uranium districts allowed the authors to develop an evolutionary geological model of large-scale uranium ore genesis, which reflects the succession and nature of preore, ore-forming, and post-ore processes. The study reveals a combination of general (recurrent) factors controlling the formation of ore districts with large-scale uranium mineralization regardless of the genesis and timing of the mineralization. At the same time, these factors depend on the regional setting and can vary considerably among deposits of the same type localized in different tectonic blocks with different characteristics and structural evolution. In connection with this, the exploration of major genetic types of deposits requires the application of specified criteria. Along with the consideration of the evolutionary geological model of ore formation, the study discusses a variety of tectono-magmatic, mineralogical, geochemical, radiogeochemical, and physicochemical factors and indications in three uranium districts (the Streltsovskoe, Elkon, and Central Ukrainian districts), which can form the basis for further uranium prospecting and exploration. Using a combination of favorable prerequisite conditions the study compares the possibilities for the discovery of large endogenic uranium deposits in several regions of Russia.

  16. Porphyry-copper ore shells form at stable pressure-temperature fronts within dynamic fluid plumes.

    PubMed

    Weis, P; Driesner, T; Heinrich, C A

    2012-12-21

    Porphyry-type ore deposits are major resources of copper and gold, precipitated from fluids expelled by crustal magma chambers. The metals are typically concentrated in confined ore shells within vertically extensive vein networks, formed through hydraulic fracturing of rock by ascending fluids. Numerical modeling shows that dynamic permeability responses to magmatic fluid expulsion can stabilize a front of metal precipitation at the boundary between lithostatically pressured up-flow of hot magmatic fluids and hydrostatically pressured convection of cooler meteoric fluids. The balance between focused heat advection and lateral cooling controls the most important economic characteristics, including size, shape, and ore grade. This self-sustaining process may extend to epithermal gold deposits, venting at active volcanoes, and regions with the potential for geothermal energy production.

  17. Effect of polydisperse sintering ore on the pelletizing of fine concentrates

    NASA Astrophysics Data System (ADS)

    Trushko, V. L.; Utkov, V. A.

    2016-01-01

    An addition of the polydisperse Yakovlevo deposit sintering ore on the efficiency of pelletizing and, hence, the gas permeability of a sintering mixture containing fine concentrates is studied. This sintering ore is found to have unique properties, which make it possible to increase the iron content in a sinter and to improve the gas permeability of a sintering mixture significantly (by a factor of 2-4). As a result, the sintering machine capacity can be substantially increased, the strength of the sinter can be increased at a lower fuel flow rate and lower lime consumption, and the blast furnace capacity can be substantially improved at lower consumption of expensive coke. Therefore, this version of using the Yakovlevo deposit sintering ore has a high economic efficiency.

  18. Porphyry-copper ore shells form at stable pressure-temperature fronts within dynamic fluid plumes.

    PubMed

    Weis, P; Driesner, T; Heinrich, C A

    2012-12-21

    Porphyry-type ore deposits are major resources of copper and gold, precipitated from fluids expelled by crustal magma chambers. The metals are typically concentrated in confined ore shells within vertically extensive vein networks, formed through hydraulic fracturing of rock by ascending fluids. Numerical modeling shows that dynamic permeability responses to magmatic fluid expulsion can stabilize a front of metal precipitation at the boundary between lithostatically pressured up-flow of hot magmatic fluids and hydrostatically pressured convection of cooler meteoric fluids. The balance between focused heat advection and lateral cooling controls the most important economic characteristics, including size, shape, and ore grade. This self-sustaining process may extend to epithermal gold deposits, venting at active volcanoes, and regions with the potential for geothermal energy production. PMID:23160957

  19. [Studies of radioactivity in the ores and mineral products].

    PubMed

    Brovtsyn, A K

    2004-01-01

    Mineral ores and products made of them were studied by gamma-spectrophotometry. Regularities of radionuclide content in ores and products were found. A possibility of deactivation of ores and mineral products by the technology of aerohydrodynamic concentration was shown.

  20. The dating of ore genesis with using of sulfides: new opportunities of Sm-Nd method

    NASA Astrophysics Data System (ADS)

    Ekimova, N.; Serov, P.; Bayanova, T.

    2012-04-01

    not able to significantly influence on the results of Sm-Nd analysis. For the first time with sulfide minerals as minerals-geochronometers in Sm-Nd method have been dated impregnated and brecciform ores of the following objects - Pilguyarvi Cu-Ni deposits, Pechenga (1965 ± 87 Ma); impregnated (2433 ± 83 Ma) and redeposited (1903 ± 24 Ma) ores of Ahmavaara intrusion; ore gabbronorites of Penikat intrusion (2426±38 Ma (Ekimova et.al., 2011); gabbro-anorthosite ore (2476 ± 41 Ma, which agrees well with the U-Pb zircon age - 2470 ± 9 Ma (Bayanova, 2004)) and gabbronorites (2483 ± 86 Ma) of Kievei deposit and Fedorova Tundra metagabbroids (2494 ± 54 Ma). For these ores, except redeposited Ahmavaara ore, justified their crystallization from the melt, the simultaneous crystallization of the bulk rock. Thus, studies have shown quite correct, supported by other geochronological and instrumental methods, results, and given the opportunity to determine the time frames of the main ore genesis industrially important platinum metal objects. These studies were supported by the RFBR 10-05-00058, 11-05-00570, OFI-M 11-05-12028.

  1. Extraction of copper from an oxidized (lateritic) ore using bacterially catalysed reductive dissolution.

    PubMed

    Nancucheo, Ivan; Grail, Barry M; Hilario, Felipe; du Plessis, Chris; Johnson, D Barrie

    2014-01-01

    An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined. PMID:24687752

  2. Extraction of copper from an oxidized (lateritic) ore using bacterially catalysed reductive dissolution.

    PubMed

    Nancucheo, Ivan; Grail, Barry M; Hilario, Felipe; du Plessis, Chris; Johnson, D Barrie

    2014-01-01

    An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined.

  3. Genesis of ion-adsorption type REE ores in Thailand

    NASA Astrophysics Data System (ADS)

    Sanematsu, K.; Yoshiaki, K.; Watanabe, Y.

    2012-04-01

    Ion-adsorption type REE deposits, which have been economically mined only in southern China, are predominant supply sources for HREE in the world. The ore bodies consist of weathered granites called ion-adsorption ores. The majority of REE (>50 %) are electrostatically adsorbed onto weathering products in the ores and they can be extracted by ion exchange using an electrolyte solution (e.g., ammonium sulfate solution). Recently the occurrences of ion-adsorption ores have been reported in Indochina, SE Asia. In this study, we discuss geochemical and mineralogical characteristics of parent granites and weathered granites in Thailand in order to reveal the genesis of ion-adsorption ores. Permo-Triassic and Cretaceous-Paleogene granite plutons are distributed from northern Thailand to western Indonesia through eastern Myanmar and Peninsular Malaysia. They are mostly ilmenite-series calcalkaline biotite or hornblende-biotite granites. REE contents of the granites range from 60 to 600 ppm and they are relatively high in Peninsula Thailand. REE-bearing minerals consist mainly of apatite, zircon, allanite, titanite, monazite and xenotime. Some I-type granites contain REE fluorocarbonate (probably synchysite-(Ce)) in cavities and cracks in feldspars and it is the dominant source of REE for ion-adsorption ores because the fluorocarbonate is easily soluble during weathering. In contrast, insoluble monazite and xenotime are not preferable for ion-adsorption ores although they are common ore minerals of placer REE deposits. Weathered granites show REE contents ranging from 60 to 1100 ppm in Thailand because REE are relatively immobile compared with mobile elements (e.g., Na, K, Ca). In the weathered granites, REE are contained in residual minerals and secondary minerals and are adsorbed onto the surface of weathering products. A weathering profile of granite with ion-adsorption type mineralization can be divided into upper and lower parts based on REE enrichment and Ce

  4. Iron ore: energy, labor, and capital changes with technology.

    PubMed

    Kakela, P J

    1978-12-15

    Resource gathering is depending on leaner crude ores. Iron ore mining typifies this trend. To make lean taconite iron ores useful required a technologic breakthrough-pelletization. The shift to iron ore pellets has the advantage that they require less energy and labor per ton of molten iron than high-grade naturally concentrated ores. Increased reliance on pellets causes a geographic shift of some jobs and environmental effects from blast furnaces to iron ore mines. PMID:17735387

  5. Iron ore: energy, labor, and capital changes with technology.

    PubMed

    Kakela, P J

    1978-12-15

    Resource gathering is depending on leaner crude ores. Iron ore mining typifies this trend. To make lean taconite iron ores useful required a technologic breakthrough-pelletization. The shift to iron ore pellets has the advantage that they require less energy and labor per ton of molten iron than high-grade naturally concentrated ores. Increased reliance on pellets causes a geographic shift of some jobs and environmental effects from blast furnaces to iron ore mines.

  6. Enrichment Wastes' Processing of Manganiferous Ores with the Use of Mechanochemical Methods

    ERIC Educational Resources Information Center

    Kubekova, Sholpan N.; Kapralova, Viktoria I.; Ibraimova, Gulnur T.; Batyrbayeva, Aigul A.

    2016-01-01

    The aim of the research is the study of the chemical and phase composition of enrichment wastes of manganiferous ore in Ushkatyn-III deposit and the synthesis of new materials by mechanochemical activation and subsequent heat treatment of the mechanical activation products. The use of XFA, infrared spectroscopy and electron probe microanalysis…

  7. Some limitations on the possible composition of the ore-forming fluid

    USGS Publications Warehouse

    Barton, Paul B.

    1956-01-01

    The activity rations of various important anions (S, CO3, SO4, OH, F, and Cl) in hydrothermal solutions at the time of deposition are evaluated using a simple thermodynamic technique. The rations are interpreted in the light of the mineralogy of ore deposits and limites are placed on the variability of each ratio in hydrothermal solutions. All of the calculations are made for 25°C and cautious extrapolation to higher temperatures seems justified; however, additional data for elevated temperatures and pressures are needed before more than approximate values may be assigned to these ratios in the ore-forming fluid. The calculated partial pressure of CO2 in the ore fluid is generally less than one atmosphere, which suggests that a dense CO2 phase cannot be considered an importatn ore fluid for most deposits. The partial pressure of H2S is usually less than 10-4 atmospheres which makes it extremely difficult to defend the heory that metals (other than the easily complexible mercury, arsenic, antimony, and perhaps fols and silver) are transported in quantity as complex sulfide and hydrosulfides. The sulfate to sulfide ration is such that the oxidation potential at the time of deposition is defined by the following equation: Eh (in volts) = 0.22 ± 0.04 - 0.059 pH.

  8. 43 CFR 9239.5-1 - Ores.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Ores. 9239.5-1 Section 9239.5-1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR TECHNICAL SERVICES (9000) TRESPASS Kinds of Trespass § 9239.5-1 Ores. (a) For...

  9. 43 CFR 9239.5-1 - Ores.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Ores. 9239.5-1 Section 9239.5-1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR TECHNICAL SERVICES (9000) TRESPASS Kinds of Trespass § 9239.5-1 Ores. (a) For...

  10. 43 CFR 9239.5-1 - Ores.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Ores. 9239.5-1 Section 9239.5-1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR TECHNICAL SERVICES (9000) TRESPASS Kinds of Trespass § 9239.5-1 Ores. (a) For...

  11. 43 CFR 9239.5-1 - Ores.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Ores. 9239.5-1 Section 9239.5-1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR TECHNICAL SERVICES (9000) TRESPASS Kinds of Trespass § 9239.5-1 Ores. (a) For...

  12. Mercury from mineral deposits and potential environmental impact

    USGS Publications Warehouse

    Rytuba, J.J.

    2003-01-01

    Mercury deposits are globally distributed in 26 mercury mineral belts. Three types of mercury deposits occur in these belts: silica-carbonate, hot-spring, and Almaden. Mercury is also produced as a by-product from several types of gold-silver and massive sulfide deposits, which account for 5% of the world's production. Other types of mineral deposits can be enriched in mercury and mercury phases present are dependent on deposit type. During processing of mercury ores, secondary mercury phases form and accumulate in mine wastes. These phases are more soluble than cinnabar, the primary ore mineral, and cause mercury deposits to impact the environment more so than other types of ore deposits enriched in mercury. Release and transport of mercury from mine wastes occur primarily as mercury-enriched particles and colloids. Production from mercury deposits has decreased because of environmental concerns, but by-product production from other mercury-enriched mineral deposits remains important.

  13. Study of Munella Ores. (puka Region, Albania)

    NASA Astrophysics Data System (ADS)

    Liçaj, Engjell; Mandili, Jorgo; Tabaku, Boran; Thomo, Niko

    2010-01-01

    The study of Munella ores is based on four analysis (A, B, Cand cores). They represent different types of minerals in the Munella area. Cores were taken by the geologist of Puka Geological Enterprise. A Core: It represents an ore with pyrite and chalcopyrite where copper and sulfur contents are 0.77 and 8.2% respectively. B Core: This core represents an ore with spharelites and pyrite where zinc content is 1.5% and 2.9% sulfur one. C Core: It is a chalcopyrite ore, massive in nature, where copper content is 2.01% and 36% sulfur one. D Core: It also represents copper- zinc—sulfur ore where their content is 0.66, 1.00 and 4.28% respectively. Each core is studied individually by selective schema to have copper, zinc and pyrite concentrates. Copper and pyrite concentrates will be the first material for pyro- metallurgical industry.

  14. Deformation, metamorphism, and mobilization of Ni-Cu-PGE sulfide ores at Garson Mine, Sudbury

    NASA Astrophysics Data System (ADS)

    Mukwakwami, Joshua; Lafrance, Bruno; Lesher, C. Michael; Tinkham, Douglas K.; Rayner, Nicole M.; Ames, Doreen E.

    2014-02-01

    The Garson Ni-Cu-platinum group element deposit is a deformed, overturned, low Ni tenor contact-type deposit along the contact between the Sudbury Igneous Complex (SIC) and stratigraphically underlying rocks of the Huronian Supergroup in the South Range of the 1.85-Ga Sudbury structure. The ore bodies are coincident with steeply south-dipping, north-over-south D1 shear zones, which imbricated the SIC, its ore zones, and underlying Huronian rocks during mid-amphibolite facies metamorphism. The shear zones were reactivated as south-over-north, reverse shear zones during D2 at mid-greenschist facies metamorphism. Syn-D2 metamorphic titanite yields an age of 1,849 ± 6 Ma, suggesting that D1 and D2 occurred immediately after crystallization of the SIC during the Penokean Orogeny. The ore bodies plunge steeply to the south parallel to colinear L1 and L2 mineral lineations, indicating that the geometry of the ore bodies are strongly controlled by D1 and D2. Sulfide mineralization consists of breccia ores, with minor disseminated sulfides hosted in norite, and syn-D2 quartz-calcite-sulfide veins. Mobilization by ductile plastic flow was the dominant mechanism of sulfide/metal mobilization during D1 and D2, with additional minor hydrothermal mobilization of Cu, Fe, and Ni by hydrothermal fluids during D2. Metamorphic pentlandite overgrows a S1 ferrotschermakite foliation in D1 deformed ore zones. Pentlandite was exsolved from recrystallized polygonal pyrrhotite grains after cessation of D1, which resulted in randomly distributed large pentlandite grains and randomly oriented pentlandite loops along the grain boundaries of polygonal pyrrhotite within the breccia ore. It also overgrows a S2 chlorite foliation in D2 shear zones. Pyrrhotite recrystallized and was flattened during D2 deformation of breccia ore along narrow shear zones. Exsolution of pentlandite loops along the grain boundaries of these flattened grains produced a pyrrhotite-pentlandite layering that is not

  15. Process for desulfurization of coal and ores

    SciTech Connect

    Starbuck, A.

    1980-07-22

    A process for desulfurizing ores containing sulfur comprises the steps of: (A) crushing ore containing sulfur to a particle consistency; (B) feeding the crushed ore to a heated continuous-flow processor; (C) introducing pre-heated sulfur dissolving solvent into said processor with the crushed ore; (D) concurrently mixing and force conveying the crushed ore and solvent by augering in the continuous flow processor at an elevated temperature in which sulfur is dissolvable and is dissolved in a heated sulfur-solvent solution with suspended particles and a remaining ore, the processor being oriented for about horizontal augering; (E) separating the sulfur-solvent solution with suspended particles from the remaining ore at an elevated temperature; (F) drying the separated, remaining ore by evaporating remaining solvent from the ore; (G) recovering solvent from the ore drying step by condensing the evaporated solvent; (H) concurrently crystallizing sulfur dissolved in the sulfur-solvent solution and force conveying the sulfur-solvent solution and crystallizing sulfur by augering a continuous flow chilled processor wherein the sulfur-solvent solution and crystallizing sulfur are conveyed together in a concurrent manner as a mixture in a continuous forward direction at controlled reduced temperatures as substantially the entire mixture progresses to a separate separating step, said crystallizing sulfur existing in part as a suspension and in part as a precipitate; (I) separating both crystallized suspension sulfur and crystallized precipitate sulfur from the solvent solution; (J) drying the separated crystallized sulfur by evaporating the solvent from the crystallized sulfur, wherein a fine crystal sulfur product is obtained; and (K) recovering solvent from the crystallized sulfur drying step by condensing the veaporated solvent.

  16. Fluid inclusion, rare earth element geochemistry, and isotopic characteristics of the eastern ore zone of the Baiyangping polymetallic Ore district, northwestern Yunnan Province, China

    NASA Astrophysics Data System (ADS)

    Feng, Caixia; Bi, Xianwu; Liu, Shen; Hu, Ruizhong

    2014-05-01

    conditions of seawater sulfate reduction to sulfur. (4) The C-O isotopic analyses yield δ13C values from ca. zero to -10‰, and a wider range of δ18O values from ca. +6 to +24‰, suggestive of mixing between mantle-derived magma and marine carbonate sources during the evolution of ore-forming fluids, although potential contributions from organic carbon and basinal brine sources should also be considered. These data indicate that ore-forming fluids were derived from a mixture of organism, basinal brine, and mantle-derived magma sources, and as such, the eastern ore zone of the Baiyangping polymetallic ore deposit should be classified as a “Lanping-type” ore deposit.

  17. The Formation of Banded Zebra Rocks, Permeability Changes and Ore Formation

    NASA Astrophysics Data System (ADS)

    Koehn, D.; Chung, P.

    2012-04-01

    Dolomites can develop characteristic patterns of white and dark bands that form so called "Zebra" rocks. Often these patterns are mineralized and host ore deposits. How the Zebra stripes form and what effect their formation has on permeability changes within rocks is not well understood. In this contribution we study striped dolomites from the San Vicente Lead-Zink mine in Peru in order to understand how the pattern forms and how it influences the development of the ore deposit. We analysed thin-sections under an optical microscope and the SEM in order to map the difference between the white and dark bands of dolomite. The main difference between the two is the grain size, where dark bands always contain smaller grains than white bands. This leads to a marked difference in permeability, with the large grains in the white bands containing open space and ore-filled holes. EDS mapping of Si and Al shows that the dark bands mainly contain these elements and that they are absent in the large grains. This can also be seen in thin-section where the dark bands seem to contain the main impurities. Because of the difference in grain size and impurity content we argue that the pattern forms due to a grain-growth process where grains in the white bands grow without including impurities whereas grains in the dark bands shrink and collect impurities. This in turn also influences the permeability of the system where white layers become more permeable. Lead seems to precipitate mainly in these high permeability regions in the middle of the white bands whereas Zink travels to the boundary between white and dark bands where Sphalerite precipitates. Structures of the precipitated ore minerals indicate that the dolomite dissolves while the ore minerals precipitate. We will discuss implications of our model for this specific type of ore deposits.

  18. Depositional environment and origin of the Lilaozhuang Neoarchean BIF-hosted iron-magnesite deposit on the southern margin of the North China Craton

    NASA Astrophysics Data System (ADS)

    Huang, Hua; Zhang, LianChang; Fabre, Sébastien; Wang, ChangLe; Zhai, MingGuo

    2016-08-01

    The Neoarchean Lilaozhuang iron-magnesite deposit is located in the middle of the Huoqiu banded iron formation (BIF) ore belt in Anhui Province on the southern margin of the North China Craton. The Huoqiu BIF is the unique one that simultaneously develops quartz-type, silicate-type, and carbonate-type magnetite in the region. The Lilaozhuang deposit is characterized by magnesium-rich carbonate (magnesite) in magnetite ores. The BIF-hosted iron ores include mainly of silicate type and carbonate type, with a small amount of quartz type, which chiefly exhibit banded and massive structure, with minor disseminated structure. The magnesite ores occur as crystal-like bright white and exhibits massive structure. The Y/Ho ratio and REY pattern of both iron and magnesite ores are similar to that of seawater, while Eu shows positive anomaly, which is the sign of seafloor hydrothermal mixture. These features suggest that ore-forming materials of iron and magnesium in the Lilaozhuang deposit are mainly from the mixture of seafloor hydrothermal and seawater. Both ores do not exhibit negative Ce anomaly, which indicates that the deposit was formed in an environment showing a lack of oxygen. C-O isotopic compositions indicate that magnesite ore has been reformed by metamorphism of low amphibolite facies and later hydrothermal alteration. Based on the comprehensive analysis, authors suggest that iron and magnesite ores in the Lilaozhuang deposits formed in a confined sea basin on continental margin and was influenced by later complex geological processes.

  19. Gemstone deposits of Serbia

    NASA Astrophysics Data System (ADS)

    Miladinović, Zoran; Simić, Vladimir; Jelenković, Rade; Ilić, Miloje

    2016-06-01

    Gemstone minerals in Serbia have never been regarded as an interesting and significant resource. Nevertheless, more than 150 deposits and occurrences have been recorded and some of them preliminarily explored in the last 50 years. The majority of deposits and occurrences are located within the Serbo-Macedonian metallogenic province and the most significant metallogenic units at the existing level of knowledge are the Fruska Gora ore district, Cer ore district, Sumadija metallogenic zone, Kopaonik metallogenic zone and Lece-Halkidiki metallogenic zone. The most important genetic type of deposits is hydrothermal, particularly in case of serpentinite/peridotite as host/parent rock. Placer deposits are also economically important. The dominant gemstones are silica minerals: chalcedony (Chrysoprase, carnelian, bluish chalcedony etc.), jasper (picture, landscape, red etc.), common opal (dendritic, green, milky white etc.), silica masses (undivided), and quartz (rock crystal, amethyst etc.). Beside silica minerals significant gemstones in Serbia include also beryl (aquamarine), garnet (almandine and pyrope), tourmaline, fluorite, rhodochrosite, carbonate-silica breccia, carbonate-silica onyx, silicified wood, howlite, serpentinite, marble onyx, and kyanite. This paper aims to present an overview of Serbian gemstone deposits and occurrences and their position based on a simplified gemstone metallogenic map of Serbia, as well as genetic-industrial classification of gemstone deposits and gemstone varieties.

  20. 25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE STORAGE YARD. AN ORE BRIDGE THAT FORMERLY TRANSFERRED ORE WITHIN THE STORAGE YARD WAS DESTROYED BY A BLIZZARD IN 1978. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  1. 36. ORE DOCK, LOOKING WEST. HULETT UNLOADERS AWAIT THE NEXT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. ORE DOCK, LOOKING WEST. HULETT UNLOADERS AWAIT THE NEXT ORE BOAT. BY LATE WINTER, THE ORE STORAGE YARD SEEN AT LEFT WILL BE DEPLETED. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  2. The Role of Groundwater Flow and Faulting on Hydrothermal Ore Formation in Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Garven, G.

    2006-05-01

    Sediment-hosted ore formation is thought to occur as a normal outcome of basin evolution, due to deep groundwater flow, heat transport, and reactive mass transport ---all of which are intimately coupled. This paper reviews recent attempts to understand the hydrologic and geochemical processes forming some of the world's largest sediment-hosted ores. Several questions still dominate the literature (driving forces for flows, source and controls on metal acquisition, concentrations of ore-forming components, timing and duration, role of faults, effects of transient flows). This paper touches upon all of these questions. Coupled reactive transport models have been applied for understanding the genesis of sandstone-hosted uranium ores of North America and Australia, red-bed copper ores of North America and northern Europe, carbonate-hosted MVT lead-zinc ores of the U.S. Midcontinent and northwestern Canada, and the carbonate- hosted lead-zinc ores of Ireland and southeast France. Good progress has been made in using these computational methods for comparing and contrasting both carbonate hosted (MVT and Irish types) and shale- hosted (SEDEX type) Pb-Zn deposits. The former are mostly associated with undeformed carbonate platforms associated with distal orogenic belts and the later are mostly associated with extensional basins and failed rifts that are heavily faulted. Two giant ore provinces in extensional basins provide good examples of structural control on reactive mass transport: shale-hosted Pb-Zn ores of the Proterozoic McArthur basin, Australia, and shale-hosted Pb-Zn-Ba ores of the Paleozoic Kuna basin, Alaska. For the McArthur basin, hydrogeologic simulations of thermally-driven free convection suggest a strong structural control on fluid flow created by the north-trending fault systems that dominate this Proterozoic extensional basin. Brines appear to have descended to depths of a few kilometers along the western side of the basin, migrated laterally to the

  3. Origin of marcasite and its implications regarding the genesis of roll-front uranium deposits

    USGS Publications Warehouse

    Goldhaber, Martin B.; Reynolds, Richard L.

    1979-01-01

    Study of five roll-type uranium deposits (three in Texas and two in Wyoming) has resulted in the recognition of ore-stage marcasite in each deposit. Ore-stage marcasite is identified by its close association with uranium- and vanadium-bearing phases in the ore zones; by its close association with ferroselite at and near the redox boundary in some deposits; by its abundance and distribution across deposits; and by its textural relationships with identifiable pre-ore iron disulfide minerals (primarily pyrite). In deposits that are essentially devoid of fossil vegetal debris, marcasite is the dominant ore-stage sulfide and occurs in a large volume of rock beyond the ore zones. In deposits that contain organic matter, ore-stage pyrite is at least as abundant as ore-stage marcasite. Many factors and processes may lead to the formation of either marcasite or pyrite as an ore-stage mineral in roll-type deposits. One of the dominant factors is the complex interrelationship of pH and sulfur species that are precursors of iron-disulfide minerals. Experimental work and study of geochemical environments analogous to those governing the formation of roll-type deposits indicate that relatively low pH (less than about six) and the presence of elemental sulfur favor marcasite, whereas higher pH and the presence of polysulfide ions favor pyrite. Conditions that favor marcasite as the dominant ore-stage iron disulfide are likely to arise during uranium deposition in host rock without fossil vegetal matter. In host rock containing carbonaceous debris, the presence of polysulfide ions and pH buffering any anaerobic bacterial metabolic processes apparently lead to the formation of ore-stage pyrite.

  4. Extraction of reduced alteration information based on Aster data: a case study of the Bashibulake uranium ore district

    NASA Astrophysics Data System (ADS)

    Ye, Fa-wang; Liu, De-chang

    2008-12-01

    Practices of sandstone-type uranium exploration in recent years in China indicate that the uranium mineralization alteration information is of great importance for selecting a new uranium target or prospecting in outer area of the known uranium ore district. Taking a case study of BASHIBULAKE uranium ore district, this paper mainly presents the technical minds and methods of extracting the reduced alteration information by oil and gas in BASHIBULAKE ore district using ASTER data. First, the regional geological setting and study status in BASHIBULAKE uranium ore district are introduced in brief. Then, the spectral characteristics of altered sandstone and un-altered sandstone in BASHIBULAKE ore district are analyzed deeply. Based on the spectral analysis, two technical minds to extract the remote sensing reduced alteration information are proposed, and the un-mixing method is introduced to process ASTER data to extract the reduced alteration information in BASHIBULAKE ore district. From the enhanced images, three remote sensing anomaly zones are discovered, and their geological and prospecting significances are further made sure by taking the advantages of multi-bands in SWIR of ASTER data. Finally, the distribution and intensity of the reduced alteration information in Cretaceous system and its relationship with the genesis of uranium deposit are discussed, the specific suggestions for uranium prospecting orientation in outer of BASHIBULAKE ore district are also proposed.

  5. Catalytic decomposition of tar derived from wood waste pyrolysis using Indonesian low grade iron ore as catalyst

    NASA Astrophysics Data System (ADS)

    Wicakso, Doni Rahmat; Sutijan, Rochmadi, Budiman, Arief

    2016-06-01

    Low grade iron ore can be used as an alternative catalyst for bio-tar decomposition. Compared to other catalysts, such as Ni, Rd, Ru, Pd and Pt, iron ore is cheaper. The objective of this research was to investigate the effect of using low grade iron ore as catalyst for tar catalytic decomposition in fixed bed reactor. Tar used in this experiment was pyrolysis product of wood waste while the catalyst was Indonesian low grade iron ore. The variables studied were temperatures between 500 - 600 °C and catalyst weight between 0 - 40 gram. The first step, tar was evaporated at 450 °C to produce tar vapor. Then, tar vapor was flowed to fixed bed reactor filled low grade iron ore. Gas and tar vapor from reactor was cooled, then the liquid and uncondensable gas were analyzed by GC/MS. The catalyst, after experiment, was weighed to calculate total carbon deposited into catalyst pores. The results showed that the tar components that were heavy and light hydrocarbon were decomposed and cracked within the iron ore pores to from gases, light hydrocarbon (bio-oil) and carbon, thus decreasing content tar in bio-oil and increasing the total gas product. In conclusion, the more low grade iron ore used as catalyst, the tar content in the liquid decrease, the H2 productivity increased and calorimetric value of bio-oil increased.

  6. Stratiform chromite deposit model

    USGS Publications Warehouse

    Schulte, Ruth F.; Taylor, Ryan D.; Piatak, Nadine M.; Seal, Robert R., II

    2010-01-01

    Stratiform chromite deposits are of great economic importance, yet their origin and evolution remain highly debated. Layered igneous intrusions such as the Bushveld, Great Dyke, Kemi, and Stillwater Complexes, provide opportunities for studying magmatic differentiation processes and assimilation within the crust, as well as related ore-deposit formation. Chromite-rich seams within layered intrusions host the majority of the world's chromium reserves and may contain significant platinum-group-element (PGE) mineralization. This model of stratiform chromite deposits is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. The model focuses on features that may be common to all stratiform chromite deposits as a way to gain insight into the processes that gave rise to their emplacement and to the significant economic resources contained in them.

  7. Deep structure and metallogeny of the Kirovograd polymetallic ore district, the Ukrainian Shield: Correlation of geological and seismic data

    NASA Astrophysics Data System (ADS)

    Kazansky, V. I.; Makivchuk, O. F.; Popov, N. I.; Drogitskaya, G. M.; Starostenko, V. I.; Tripol'Sky, A. A.; Chicherov, M. V.

    2012-02-01

    The study of deep structure of the Kirovograd ore district proceeds from a broad treatment of its geological boundaries and combination of metasomatic uranium, pegmatitic lithium, and hydrothermal gold deposits, as well as lodes of magmatic titanium ore within these boundaries. The spatial juxtaposition of the Novoukrainsk-Kirovograd granitoid massif and the Korsun-Novomirgorod rapakivi granite-anorthosite massif is a distinguishing feature of the Kirovograd ore district. The former massif along with stratified metamorphic rocks forms an intrusive-ultrametamorphic basement, whereas the latter massif is autonomous with respect to the basement. Taken together, both massifs make up the Novoukrainsk-Korsun-Novomirgorod composite pluton, which determines the architecture of the Kirovograd ore district not only at the present-day erosion surface but also at deeper levels of the lithosphere. The uranium, lithium, and gold deposits are localized in the intrusive-ultrametamorphic basement and controlled by various combinations of intrinsic and superposed structures; the vertical extent of mineralization is also controlled by their combinations. Some combinations are unique. Primarily, these are triple junctions of superposed faults, which host the largest metasomatic uranium orebodies. At the same time, the deposits are spatially related to the local mediumscale trough in topography of the Moho discontinuity. This mantle trench is discordant relative to the Novoukrainsk-Korsun-Novomirgorod pluton. These and other data discussed in the paper allow us to consider the Kirovograd polymetallic ore district as a Paleoproterozoic center of crustal-mantle magmatic activity and ore formation. This center was formed 2.1-1.7 Ga ago in the course of juxtaposition of three development stages differing in associations of intrusive rocks, style of deformation and metamorphism of rocks, origin and localization of ore deposits.

  8. 63,65Cu NMR Method in a Local Field for Investigation of Copper Ore Concentrates

    NASA Astrophysics Data System (ADS)

    Gavrilenko, A. N.; Starykh, R. V.; Khabibullin, I. Kh.; Matukhin, V. L.

    2015-01-01

    To choose the most efficient method and ore beneficiation flow diagram, it is important to know physical and chemical properties of ore concentrates. The feasibility of application of the 63,65Cu nuclear magnetic resonance (NMR) method in a local field aimed at studying the properties of copper ore concentrates in the copper-iron-sulfur system is demonstrated. 63,65Cu NMR spectrum is measured in a local field for a copper concentrate sample and relaxation parameters (times T1 and T2) are obtained. The spectrum obtained was used to identify a mineral (chalcopyrite) contained in the concentrate. Based on the experimental data, comparative characteristics of natural chalcopyrite and beneficiated copper concentrate are given. The feasibility of application of the NMR method in a local field to explore mineral deposits is analyzed.

  9. Characterisation and Processing of Some Iron Ores of India

    NASA Astrophysics Data System (ADS)

    Krishna, S. J. G.; Patil, M. R.; Rudrappa, C.; Kumar, S. P.; Ravi, B. P.

    2013-10-01

    Lack of process characterization data of the ores based on the granulometry, texture, mineralogy, physical, chemical, properties, merits and limitations of process, market and local conditions may mislead the mineral processing entrepreneur. The proper implementation of process characterization and geotechnical map data will result in optimized sustainable utilization of resource by processing. A few case studies of process characterization of some Indian iron ores are dealt with. The tentative ascending order of process refractoriness of iron ores is massive hematite/magnetite < marine black iron oxide sands < laminated soft friable siliceous ore fines < massive banded magnetite quartzite < laminated soft friable clayey aluminous ore fines < massive banded hematite quartzite/jasper < massive clayey hydrated iron oxide ore < manganese bearing iron ores massive < Ti-V bearing magnetite magmatic ore < ferruginous cherty quartzite. Based on diagnostic process characterization, the ores have been classified and generic process have been adopted for some Indian iron ores.

  10. Application of the Geo-Anomaly Unit Concept in Quantitative Delineation and Assessment of Gold Ore Targets in Western Shandong Uplift Terrain, Eastern China

    SciTech Connect

    Chen Yongqing Zhao Pengda; Chen Jianguo; Liu Jiping

    2001-03-15

    A number of large and giant ore deposits have been discovered within the relatively small areas of lithospheric structure anomalies, including various boundary zones of tectonic plates. The regions have become the well-known intercontinental ore-forming belts, such as the circum-Pacific gold-copper, copper-molybdenum, and tungsten-tin metallogenic belts. These belts are typical geological anomalous areas. An investigation into the hydrothermal ore deposits in different regions in the former Soviet Union illustrated that the geologic structures of ore fields of almost all major commercial deposits have distinct features compared with the neighboring areas. These areas with distinct features are defined as geo-anomalies. A geo-anomaly refers to such a geologic body or a combination of bodies that their composition, texture-structure, and genesis are significantly different from those of their surroundings. A geo-anomaly unit (GU) is an area containing distinct features that can be delineated with integrated ore-forming information using computer techniques on the basis of the geo-anomaly concept. Herein, the GU concept is illustrated by a case study of delineating the gold ore targets in the western Shandong uplift terrain, eastern China. It includes: (1) analyses of gold ore-forming factors; (2) compilation of normalized regional geochemical map and extraction of geochemical anomalies; (3) compilation of gravitational and aeromagnetic tectonic skeleton map and extraction of gravitational and aeromagnetic anomalies; (4) extraction of circular and linear anomalies from remote-sensing Landsat TM images; (5) establishment of a geo-anomaly conceptual model associated with known gold mineralization; (6) establishment of gold ore-forming favorability by computing techniques; and (7) delineation and assessment of ore-forming units. The units with high favorability are suggested as ore targets.

  11. Sr isotopic evidence for fluid mixing in ore-stage dolomites, Pine Point, Northwest Territories, Canada

    NASA Astrophysics Data System (ADS)

    Gleeson, S. A.; Gromek, P.; Simonetti, A.

    2009-05-01

    The carbonate hosted Pb-Zn deposits of the Pine Point district (Northwest Territories) are located close to the eastern edge of the present day Western Canadian Sedimentary Basin. The deposits have been classified as Mississippi Valley Type deposits and are thought to have formed as the result of basin-wide fluid flow in the Presqu'ile barrier, the host to the ore deposits. Laser multi-collector ICP-MS study of 87Sr/86Sr ratios of ore- related dolomites from Pine Point indicate two sources of Sr were present in the mineralizing system. Fluid "A" has a range in Sr isotopic values from 0.07070 to 0.7120 and is a brine derived from Middle Devonian seawater which has undergone some interaction with clastic units in the basin. Fluid "B" has is more enriched in 87Sr and has 87Sr/86Sr ratios up to up to 0.7152, values similar to those found in Canadian Shield Brines, and represents a fluid which has interacted with crystalline basement rocks. The presence of this second Sr source in the ore forming system suggests that sulfide deposition at Pine Point occurred as a result of fluid mixing.

  12. Radioactive deposits of Nevada

    USGS Publications Warehouse

    Lovering, T.G.

    1953-01-01

    Thirty-five occurrences of radioactive rocks had been reported from Nevada prior to 1952. Twenty-five of these had been investigated by the U. S. Geological Survey and the U. S. Atomic Energy Commission. Of those investigated, uranium minerals were identified in 13; two contained a thorium mineral (monazite); the source of radioactivity on 7 properties was not ascertained; and one showed no abnormal radioactivity. Of the other reported occurrences, one is said to contain uraniferous hydrocarbons and 9 are placers containing thorian monazite. Pitchblende occurs at two localities; the East Walker River area, and the Stalin's Present prospect, where it is sparsely disseminated in tabular bodies cutting granitic rocks. Other uranium minerals found in the state include: carnotite, tyuyamunite, autunite, torbernite, gummite, uranophane, kasolite, and an unidentified mineral which may be dumontit. Monazite is the only thorium mineral of possible economic importance that has been reported. From an economic standpoint 9 only 4 of the properties examined showed reserves of uranium ore in 1952; these are: the Green Monster mine, which shipped 5 tons of ore to Marysvale, Utah, during 1951, the Majuba Hill mine, the Stalin's Present prospect, and the West Willys claim in the Washington district. Reserves of ore grade are small on all of these properties and probably cannot be developed commercially unless an ore-buying station is set up nearby. No estimate has been made of thorium reserves and no commercial deposits of thorium are known.

  13. The geology and ore deposits of the Bisbee quadrangle, Arizona

    USGS Publications Warehouse

    Ransome, F.L.

    1904-01-01

    The Bisbee quadrangle lies in Cochise County, in the southeastern part of Arizona, within what has been called in a previous paper the mountain region of the Territory. It is inclosed between meridians 109 ° 45' and 110 ° 00' and parallels 31° 30' and 31 ° 20', the latter being locally the Mexican boundary line. The area of the quadrangle is about 170 square miles, and includes the southeastern half of the Mule Mountains, one of the smaller of the isolated ranges so characteristic of the mountain region of Arizona. The Mule Mountains, while less markedly linear than the Dragoon, Huachuca, Chiricahua, and other neighboring ranges, have a general northwest-southeast trend. They may be considered as extending from the old mining town of Tombstone to the Mexican border, a distance of about 30 miles. On the northeast they are separated by the broad fiat floor of Sulphur Spring Valley form the Chiricahua Range, and on the southwest by the similar broad valley of the Rio San Pedro from the Huachuca Range (Pl. V, A). 

  14. Geology and ore deposits of the Philipsburg quadrangle, Montana

    USGS Publications Warehouse

    Emmons, William Harvey; Calkins, Frank Cathcart

    1913-01-01

    Philipsburg lies about midway between the eastern and western limits of the Rocky Mountain system, if the term be used in the broad sense prevailing in the United States. In the general latitude of Montana the system as defined by American usage is bounded on the west by the Columbia River basalt plain and on the east by the Great Plains. The western limit is fairly definite, but on the east there is no very definite line between the plains and mountains; the mountains are fairly continuous west and north of the Philipsburg quadrangle, but to the east and southeast mountains alternate with broad stretches of semiarid lowland. The quadrangle therefore overlaps the line between two physiographic provinces, one characterized by isolated mountain groups, of which the Flint Creek Range is the most westerly, and the other by more continuous elevations, of which the Sapphire Mountains are an example.

  15. Selenium content in sulfide ores from the Chalkidiki peninsula, Greece.

    PubMed

    Nicolaidou, A E

    1998-01-01

    Selenium (Se) was assessed in galena, sphalerite, and pyrite samples. These are components of mixed sulfide ores from the Olympias and Madem Lakkos-Mavres Petres deposits and the Skouries porphyry-copper deposit. We used atomic absorption spectroscopy (AAS) with a hydride generator system. The highest concentration of Se (516 ppm) was found in the fine-grained galena at the -135 level of the Olympias deposits. In the Madem Lakkos-Mavres Petres deposit, the highest concentration of Se (33 ppm) was found in the pyrites of the level 30. The concentration of Se in the arsenopyrites and chalcopyrites is lower than the detection limit of the analytical method (< 100 ppb). The concentrated chalcopyrite from the porphyry copper deposit at Skouries exhibits a significant Se content (average 200 ppm) in contrast to the chalcopyrite from the Olympias and the Madem Lakkos-Mavres Petres. Variations in the Se content of the sulfide minerals studied could be caused by redox-pH and/or temperature conditions, as well as by the difference in crystal structure. The Se found in the areas studied may positively affect the environment. Sulfide minerals are oxidized by microorganisms, infiltrate in the soil-water in the form of selenate or selenite ion, and directly or indirectly influence the human organism. PMID:9726790

  16. Selenium content in sulfide ores from the Chalkidiki peninsula, Greece.

    PubMed

    Nicolaidou, A E

    1998-01-01

    Selenium (Se) was assessed in galena, sphalerite, and pyrite samples. These are components of mixed sulfide ores from the Olympias and Madem Lakkos-Mavres Petres deposits and the Skouries porphyry-copper deposit. We used atomic absorption spectroscopy (AAS) with a hydride generator system. The highest concentration of Se (516 ppm) was found in the fine-grained galena at the -135 level of the Olympias deposits. In the Madem Lakkos-Mavres Petres deposit, the highest concentration of Se (33 ppm) was found in the pyrites of the level 30. The concentration of Se in the arsenopyrites and chalcopyrites is lower than the detection limit of the analytical method (< 100 ppb). The concentrated chalcopyrite from the porphyry copper deposit at Skouries exhibits a significant Se content (average 200 ppm) in contrast to the chalcopyrite from the Olympias and the Madem Lakkos-Mavres Petres. Variations in the Se content of the sulfide minerals studied could be caused by redox-pH and/or temperature conditions, as well as by the difference in crystal structure. The Se found in the areas studied may positively affect the environment. Sulfide minerals are oxidized by microorganisms, infiltrate in the soil-water in the form of selenate or selenite ion, and directly or indirectly influence the human organism.

  17. 8. EAST ELEVATION OF SKIDOO MILL AND UPPER ORE BIN, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. EAST ELEVATION OF SKIDOO MILL AND UPPER ORE BIN, LOOKING WEST FROM ACCESS ROAD. THE ROADWAY ON THIS LEVEL (CENTER) WAS USED FOR UNLOADING ORE BROUGHT ON BURROWS INTO THE ORE BIN AT THE TOP LEVEL OF THE MILL. THE ORE BIN IN THE UPPER LEFT WAS ADDED LATER WHEN ORE WAS BROUGHT TO THE MILL BY TRUCKS. - Skidoo Mine, Park Route 38 (Skidoo Road), Death Valley Junction, Inyo County, CA

  18. Biomining: metal recovery from ores with microorganisms.

    PubMed

    Schippers, Axel; Hedrich, Sabrina; Vasters, Jürgen; Drobe, Malte; Sand, Wolfgang; Willscher, Sabine

    2014-01-01

    Biomining is an increasingly applied biotechnological procedure for processing of ores in the mining industry (biohydrometallurgy). Nowadays the production of copper from low-grade ores is the most important industrial application and a significant part of world copper production already originates from heap or dump/stockpile bioleaching. Conceptual differences exist between the industrial processes of bioleaching and biooxidation. Bioleaching is a conversion of an insoluble valuable metal into a soluble form by means of microorganisms. In biooxidation, on the other hand, gold is predominantly unlocked from refractory ores in large-scale stirred-tank biooxidation arrangements for further processing steps. In addition to copper and gold production, biomining is also used to produce cobalt, nickel, zinc, and uranium. Up to now, biomining has merely been used as a procedure in the processing of sulfide ores and uranium ore, but laboratory and pilot procedures already exist for the processing of silicate and oxide ores (e.g., laterites), for leaching of processing residues or mine waste dumps (mine tailings), as well as for the extraction of metals from industrial residues and waste (recycling). This chapter estimates the world production of copper, gold, and other metals by means of biomining and chemical leaching (bio-/hydrometallurgy) compared with metal production by pyrometallurgical procedures, and describes new developments in biomining. In addition, an overview is given about metal sulfide oxidizing microorganisms, fundamentals of biomining including bioleaching mechanisms and interface processes, as well as anaerobic bioleaching and bioleaching with heterotrophic microorganisms.

  19. Biomining: metal recovery from ores with microorganisms.

    PubMed

    Schippers, Axel; Hedrich, Sabrina; Vasters, Jürgen; Drobe, Malte; Sand, Wolfgang; Willscher, Sabine

    2014-01-01

    Biomining is an increasingly applied biotechnological procedure for processing of ores in the mining industry (biohydrometallurgy). Nowadays the production of copper from low-grade ores is the most important industrial application and a significant part of world copper production already originates from heap or dump/stockpile bioleaching. Conceptual differences exist between the industrial processes of bioleaching and biooxidation. Bioleaching is a conversion of an insoluble valuable metal into a soluble form by means of microorganisms. In biooxidation, on the other hand, gold is predominantly unlocked from refractory ores in large-scale stirred-tank biooxidation arrangements for further processing steps. In addition to copper and gold production, biomining is also used to produce cobalt, nickel, zinc, and uranium. Up to now, biomining has merely been used as a procedure in the processing of sulfide ores and uranium ore, but laboratory and pilot procedures already exist for the processing of silicate and oxide ores (e.g., laterites), for leaching of processing residues or mine waste dumps (mine tailings), as well as for the extraction of metals from industrial residues and waste (recycling). This chapter estimates the world production of copper, gold, and other metals by means of biomining and chemical leaching (bio-/hydrometallurgy) compared with metal production by pyrometallurgical procedures, and describes new developments in biomining. In addition, an overview is given about metal sulfide oxidizing microorganisms, fundamentals of biomining including bioleaching mechanisms and interface processes, as well as anaerobic bioleaching and bioleaching with heterotrophic microorganisms. PMID:23793914

  20. New data on mineralogy and metallogeny of scarns in the Pitkyaranta ore region

    NASA Astrophysics Data System (ADS)

    Ivashchenko, V. I.; Valkama, M.; Sundblad, K.; Golubev, A. I.; Alekseev, V. Yu.

    2011-09-01

    A wide application of modern precision research techniques to the studies of Pitkyaranta ores allowed us to find increased contents of indium (to 0.33%), silver (447 g/t), gold (0.2-0.4 g/t), and palladium (0.2 g/t). A series of rare minerals previously not found here was also discovered. Among ore minerals, these are roquesite, zavartskite, electrum, stutzite, altaite, bismite, glaucodot, cervelleite, hedleyite, pavonite, cannonite, plantnerite, lindkvistite, ashoverite, etc. The discovery of roquesite and electrum is the most important in terms of metallogeny. Roquesite (indium sulfide) is found in Karelia for the first time. The highest indium contents in direct correlation to those of zinc are characteristic for polymetallic ores of the Pitkyaranta ore fields with sphalerite as the concentrating mineral (to 0.5% of In). The predicted zinc resources are evaluated to ˜2.5 million t for the Pitkyaranta group of ore deposits, and to 400 000 t for the Hopunvaara region. Respectively, the resources of indium amount to ˜2400 t (total) and 600 t for the Hopunvaara region.

  1. Metallogeny of gold deposits

    SciTech Connect

    Hutchinson, R.W.

    1985-01-01

    The metallogeny of various gold deposits, particularly their broad temporal and spatial relations, and their relations to other metallic ores, is significant to genetic understanding and also useful in exploration. Archean gold deposits co-exist, both regionally and locally, with certain iron formations, massive base metal and nickel sulfide ores, but these occur generally in differing parts of the host stratigraphic sequences. Gold deposits in marine-eugeosynclinal environments are most important and numerous in Archean rocks. They become increasingly rare in successively younger strata where epithermal deposits in subaerial-continental rocks become important. The hydrothermal systems that formed both were apparently similar; one active in submarine tectonic settings, the other in sub-volcanic continental ones. Gold was apparently first introduced extensively into supracrustal rocks by sub-sea floor hydrothermal processes in Archean time, forming gold-enriched exhalites. These were reworked by metamorphic processes forming epithermal veins in many lode districts, and by sedimentary processes in the Witwatersrand. Epithermal gold deposits were generated where these older, auriferous basement source rocks were affected by younger, plutonic-volcanic-hydrothermal activity.

  2. Platinum metals magmatic sulfide ores.

    PubMed

    Naldrett, A J; Duke, J M

    1980-06-27

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example.

  3. Geology and geochemistry of the Macheng Algoma-type banded iron-formation, North China Craton: Constraints on mineralization events and genesis of high-grade iron ores

    NASA Astrophysics Data System (ADS)

    Wu, Huaying; Niu, Xianglong; Zhang, Lianchang; Pirajno, Franco; Luo, Huabao; Qin, Feng; Cui, Minli; Wang, Changle; Qi, Min

    2015-12-01

    The Macheng iron deposit is located in the eastern Hebei province of the North China Craton (NCC). It is hosted in Neoarchean metamorphic rocks of Baimiaozi formation in the Dantazi Group, consisting of biotite-leptynite, plagioclase-gneiss, plagioclase-amphibolite, migmatite, migmatitic granite and quartz schist. Geochemical analyses of the host biotite leptynite and plagioclase amphibolites show that their protoliths are both volcanics, inferred to be trachytic basalt and basaltic andesite, respectively. Based on the geochemical signature of the host rocks, together with geology of the iron deposit, it is inferred that the Macheng BIF is an Algoma-type iron exhalative formation, formed in an arc-related basin in the Neoarchean. Post-Archean Australian Shale (PAAS)-normalized rare earth elements (REEs) plus yttrium (Y) concentrations of different BIF ores with gneissic, striated and banded structure in the Macheng deposit, show similar patterns with depletions in light rare earth elements (LREEs) and middle rare earth elements (MREEs) relative to heavy rare earth elements (HREEs) and with apparently positive La, Y and Eu anomalies. Y/Ho ratios of the gneissic, striated and banded BIF ores vary from 37 to 56. These geochemical features of the BIF ores reveal their affinity with the sea water and the presence of a high-temperature hydrothermal component, indicating that both the seawater and high temperature hydrothermal fluids derived from alteration of oceanic basalts and komatiites may contribute to formation of the Macheng BIF. Geological, mineralogical and geochemical studies of the Macheng deposit recognized two kinds of high-grade iron ores. One is massive oxidized high-grade ore (Fe2O3T = 74.37-86.20 wt.%), mainly consisting of hematite with some magnetite, which shows geochemical characteristics of the gneissic, striated and banded BIF ores. The other type is magnetite high-grade ore, also massive and consisting of magnetite, with distinct characteristics

  4. Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: II. Some general geologic applications

    USGS Publications Warehouse

    Hemley, J.J.; Hunt, J.P.

    1992-01-01

    The experimental metal solubilities for rock-buffered hydrothermal systems provide important insights into the acquisition, transport, and deposition of metals in real hydrothermal systems that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in hydrothermal systems occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors

  5. Clay mineralogy of the Greenvale Ore Body, Queensland, Australia: Implications for the interpretation of paleoclimate

    SciTech Connect

    Lev, S.; Anderson, K.; Ramirez, B.; Sun, H.; Swank, R.; Yost, D.; Huff, W.; Maynard, J.B. . Dept. of Geology)

    1994-03-01

    A 3--5% nickel enriched laterite in the Greenvale Ore Body of Queensland, Australia, is the result of weathering a serpentinized ultramafic intrusion. Variations in solubilities and drainage, typical of laterite deposits, resulted in the formation of three primary zones: (1) the Saprolite zone, (2) the Intermediate zone, and (3) the Limonite zone. Within these zones, clay mineral species with distinct chemistries and/or mineralogies have been identified, including: Ni-rich Smectite, Halloysite, and Palygorskite. Clay minerals were analyzed using powder X-ray diffraction and SEM. Bulk chemistry was determined by X-ray fluorescence in an attempt to better constrain the chemical conditions at the time of formation of the clay minerals. Results indicate a complex drainage system and history for the Greenvale Ore Body. Based on the distribution of ore grade material, it is apparent that the deposit was initially characterized by fracture controlled drainage. Owing to precipitation of Ni-rich smectite, halloysite, and palygorskite, subsequent alteration of the ore body drainage network and/or local climate can be inferred.

  6. Copper Deposits in Sedimentary and Volcanogenic Rocks

    USGS Publications Warehouse

    Tourtelot, Elizabeth B.; Vine, James David

    1976-01-01

    Copper deposits occur in sedimentary and volcanogenic rocks within a wide variety of geologic environments where there may be little or no evidence of hydrothermal alteration. Some deposits may be hypogene and have a deep-seated source for the ore fluids, but because of rapid cooling and dilution during syngenetic deposition on the ocean floor, the resulting deposits are not associated with hydrothermal alteration. Many of these deposits are formed at or near major tectonic features on the Earth's crust, including plate boundaries, rift valleys, and island arcs. The resulting ore bodies may be stratabound and either massive or disseminated. Other deposits form in rocks deposited in shallow-marine, deltaic, and nonmarine environments by the movement and reaction of interstratal brines whose metal content is derived from buried sedimentary and volcanic rocks. Some of the world's largest copper deposits were probably formed in this manner. This process we regard as diagenetic, but some would regard it as syngenetic, if the ore metals are derived from disseminated metal in the host-rock sequence, and others would regard the process as epigenetic, if there is demonstrable evidence of ore cutting across bedding. Because the oxidation associated with diagenetic red beds releases copper to ground-water solutions, red rocks and copper deposits are commonly associated. However, the ultimate size, shape, and mineral zoning of a deposit result from local conditions at the site of deposition - a logjam in fluvial channel sandstone may result in an irregular tabular body of limited size; a petroleum-water interface in an oil pool may result in a copper deposit limited by the size and shape of the petroleum reservoir; a persistent thin bed of black shale may result in a copper deposit the size and shape of that single bed. The process of supergene enrichment has been largely overlooked in descriptions of copper deposits in sedimentary rocks. However, supergene processes may be

  7. Modeling of the fault-controlled hydrothermal ore-forming systems

    SciTech Connect

    Pek, A.A.; Malkovsky, V.I.

    1993-07-01

    A necessary precondition for the formation of hydrothermal ore deposits is a strong focusing of hydrothermal flow as fluids move from the fluid source to the site of ore deposition. The spatial distribution of hydrothermal deposits favors the concept that such fluid flow focusing is controlled, for the most part, by regional faults which provide a low resistance path for hydrothermal solutions. Results of electric analog simulations, analytical solutions, and computer simulations of the fluid flow, in a fault-controlled single-pass advective system, confirm this concept. The influence of the fluid flow focusing on the heat and mass transfer in a single-pass advective system was investigated for a simplified version of the metamorphic model for the genesis of greenstone-hosted gold deposits. The spatial distribution of ore mineralization, predicted by computer simulation, is in reasonable agreement with geological observations. Computer simulations of the fault-controlled thermoconvective system revealed a complex pattern of mixing hydrothermal solutions in the model, which also simulates the development of the modern hydrothermal systems on the ocean floor. The specific feature of the model considered, is the development under certain conditions of an intra-fault convective cell that operates essentially independently of the large scale circulation. These and other results obtained during the study indicate that modeling of natural fault-controlled hydrothermal systems is instructive for the analysis of transport processes in man-made hydrothermal systems that could develop in geologic high-level nuclear waste repositories.

  8. Application of high resolution 2D/3D spectral induced polarization (SIP) in metalliferous ore exploration

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, X.; Yao, H.; He, X.; Zeng, P.; Chang, F.; Yang, Y.; Zhang, X.; Xi, X.; He, L.

    2015-12-01

    Induced polarization (IP) is a powerful tool in metalliferous ore exploration. However, there are many sources, such as clay and graphite, which can generate IP anomaly. Spectral induced polarization (SIP) measures IP response on a wide frequency range. This method provides a way to discriminate IP response generated by metalliferous ore or other objects. The best way to explore metalliferous ore is 3D SIP exploration. However, if we consider the exploration cost and efficiency, we can use SIP profiling to find an anomaly, and then use 2D/3D SIP sounding to characterize the anomaly. Based on above idea, we used a large-scale distributed SIP measurement system which can realize 800 sounding sites in one direction at the same time. This system can be used for SIP profiling, 2D/3D SIP sounding with high efficiency, high resolution, and large depth of investigation (> 1000 m). Qiushuwan copper - molybdenum deposit is located in Nanyang city, Henan province, China. It is only a middle-size deposit although over 100 holes were drilled and over 40 years of exploration were spent because of very complex geological setting. We made SIP measurement over 100 rock and ore samples to discriminate IP responses of ore and rock containing graphite. Then we carried out 7 lines of 2D SIP exploration with the depth of investigation great than 1000 m. The minimum electode spacing for potential difference is only 20 m. And we increase the spacing of current electodes at linear scale. This acquisition setting ensures high density data acquired and high quality data acquisition. Modeling and inversion result proves that we can get underground information with high resolution by our method. Our result shows that there exists a strong SIP response related to ore body in depth > 300 m. Pseudo-3D inversion of five 2D SIP sounding lines shows the location and size of IP anomaly. The new drillings based our result found a big copper-molybdenum ore body in new position with depth > 300 m and

  9. Arc-related porphyry molybdenum deposit model: Chapter D in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Taylor, Ryan D.; Hammarstrom, Jane M.; Piatak, Nadine M.; Seal, Robert R., II

    2012-01-01

    Geoenvironmental concerns are generally low because of low volumes of sulfide minerals. Most deposits are marginally acid-generating to non-acid-generating with drainage waters being near-neutral pH because of the acid generating potential of pyrite being partially buffered by late-stage calcite-bearing veins. The low ore content results in a waste:ore ratio of nearly 1:1 and large tailings piles from the open-pit method of mining.

  10. Application of Concentration-Number and Concentration-Volume Fractal Models to Recognize Mineralized Zones in North Anomaly Iron Ore Deposit, Central Iran / Zastosowanie Modeli Fraktalnych Typu K-L (Koncentracja-Liczba), Oraz K-O (Koncentracja Objętość) Do Rozpoznawania Stref Występowania Surowców Mineralnych W Regionie Złóż Rud Żelaza North Anomaly, W Środkowym Iranie

    NASA Astrophysics Data System (ADS)

    Afzal, Peyman; Ghasempour, Reza; Mokhtari, Ahmad Reza; Haroni, Hooshang Asadi

    2015-09-01

    Identification of various mineralized zones in an ore deposit is essential for mine planning and design. This study aims to distinguish the different mineralized zones and the wall rock in the Central block of North Anomaly iron ore deposit situated in Bafq (Central Iran) utilizing the concentration-number (C-N) and concentration-volume (C-V) fractal models. The C-N model indicates four mineralized zones described by Fe thresholds of 8%, 21%, and 50%, with zones <8% and >50% Fe representing wall rocks and highly mineralized zone, respectively. The C-V model reveals geochemical zones defined by Fe thresholds of 12%, 21%, 43% and 57%, with zones <12% Fe demonstrating wall rocks. Both the C-N and C-V models show that highly mineralized zones are situated in the central and western parts of the ore deposit. The results of validation of the fractal models with the geological model show that the C-N fractal model of highly mineralized zones is better than the C-V fractal model of highly mineralized zones based on logratio matrix. Identyfikacja stref występowania surowców mineralnych jest kwestia kluczową przy planowaniu wydobycia i projektowaniu kopalni. Celem pracy jest rozróżnienie stref o różnej zawartości surowców mineralnych oraz pasma skalnego w środkowej części zagłębia Bafq (środkowa cześć Iranu) przy wykorzystaniu modeli fraktalnych typu koncentracja-liczba i koncentracja-objętość. Model koncentracja-liczba pozwala na wyróżnienie czterech stref występowania surowca, definiowanych poprzez progową zawartość żelaza w rudzie na poziomie 8%, 21%, i 50% oraz strefy <8% i >50% zawartości żelaza, co odpowiada pasmu skalnemu oraz strefie o wysokim stopniu zawartości rudy. Model koncentracja-objętość wskazuje na istnienie stref geochemicznych określonych poprzez progowe wartości zawartości żelaza: 12%, 21%, 43% i 57 % oraz strefy <12%, co odpowiada ścianie skalnej. Obydwa modele stwierdzają obecność stref o wysokim stopniu zawarto

  11. Gold ore-forming fluids of the Tanami region, Northern Australia

    NASA Astrophysics Data System (ADS)

    Mernagh, Terrence P.; Wygralak, Andrew S.

    2007-01-01

    Fluid inclusion studies have been carried out on major gold deposits and prospects in the Tanami region to determine the compositions of the associated fluids and the processes responsible for gold mineralization. Pre-ore, milky quartz veins contain only two-phase aqueous inclusions with salinities ≤19 wt% NaCl eq. and homogenization temperatures that range from 110 to 410°C. In contrast, the ore-bearing veins typically contain low to moderate salinity (<14 wt% NaCl eq.), H2O + CO2 ± CH4 ± N2-bearing fluids. The CO2-bearing inclusions coexist with two-phase aqueous inclusions that exhibit a wider range of salinities (≤21 wt% NaCl eq.). Post-ore quartz and carbonate veins contain mainly two-phase aqueous inclusions, with a last generation of aqueous inclusions being very CaCl2-rich. Salinities range from 7 to 33 wt% NaCl eq. and homogenization temperatures vary from 62 to 312°C. Gold deposits in the Tanami region are hosted by carbonaceous or iron-rich sedimentary rocks and/or mafic rocks. They formed over a range of depths at temperatures from 200 to 430°C. The Groundrush deposit formed at the greatest temperatures and depths (260-430°C and ≤11 km), whereas deposits in the Tanami goldfield formed at the lowest temperatures (≥200°C) and at the shallowest depths (1.5-5.6 km). There is also evidence in the Tanami goldfield for late-stage isothermal mixing with higher salinity (≤21 wt% NaCl eq.) fluids at temperatures between 100 and 200°C. Other deposits (e.g., The Granites, Callie, and Coyote) formed at intermediate depths and at temperatures ranging from 240 to 360°C. All ore fluids contained CO2 ± N2 ± CH4, with the more deeply formed deposits being enriched in CH4 and higher level deposits being enriched in CO2. Fluids from deposits hosted mainly by sedimentary rocks generally contained appreciable quantities of N2. The one exception is the Tanami goldfield, where the quartz veins were dominated by aqueous inclusions with rare CO2-bearing

  12. Sandbox experiments on Uraninite Ore: ERT and SP measurments.

    NASA Astrophysics Data System (ADS)

    Singh, R. K.

    2015-12-01

    Nuclear energy, considering its own intrinsic merits, would be a leading source for meeting the energy requirement in present and future scenario. Concealed Uranium deposits under sedimentary cover, with poor surface indications calls for reorientation of survey with large inputs involving integrated geophysical approach. Sand Box experiments have been carried out over Uraninite ore. The tank is a glass fish tank (height 39 cm, length 75 cm, width 30 cm). It was filled with sand up to 35 cm high. The sand was saturated from below to minimize the entrapment of the gas bubbles. The average size for sand grains is ~ 0.295mm. The formation factor of the sand is 3.5, with a negligible surface conductivity because of the coarse nature of the sand grains. The dimension of considered Uraninite ore sample is 4cm x 4cm x 4cm. The depth of top of the ore sample is kept at 3cm. In this paper both resistivity and self-potential measurements were carried out for possible detection of Uraninite. The resistivity measurements were made with 64 non-polarizable electrodes using Electrical Resistivity Tomography (ERT) equipment of FlashRes Universal developed by ZZ Resistivity Imaging Pty. Ltd. We have used screws of length 3cm as electrodes. The separation between these electrodes are ~ 1cm. The resistivity tomography results clearly outlines the target Uraninite body. The resistivity tomography results also detects small heterogeneities associated with air bubbles possibly due to unsaturated pore spaces. SP measurements were made using two non-polarizing Pb/PbCl2 electrodes and a Fluke 289 voltmeter (sensitivity 0.001 mV, internal impedance 100 MOhm). The reference electrode was located on the corner of the sandbox. The other electrode was used to scan the electrical potential at the surface of the sand. SP measurements were made with a spacing of 3 cm over the same ERT profile. The SP results also shows a dip (or a low SP anomaly) over the target ore body sample. Thus, both SP and

  13. Mortality among sulfide ore miners

    SciTech Connect

    Ahlman, K.; Koskela, R.S.; Kuikka, P.; Koponen, M.; Annanmaeki, M. )

    1991-01-01

    Lung cancer mortality was studied during 1965-1985 in Outokumpu township in North Karelia, where an old copper mine was located. Age-specific lung cancer death rates (1968-1985) were higher among the male population of Outokumpu than among the North Karelian male population of the same age excluding the Outokumpu district (p less than .01). Of all 106 persons who died from lung cancer during 1965-1985 in Outokumpu township, 47 were miners of the old mine, 39 of whom had worked there for at least three years and been heavily exposed to radon daughters and silica dust. The study cohort consisted of 597 miners first employed between 1954 and 1973 by a new copper mine and a zinc mine, and employed there for at least 3 years. The period of follow-up was 1954-1986. The number of person-years was 14,782. The total number of deaths was 102; the expected number was 72.8 based on the general male population and 97.8 based on the mortality of the male population of North Karelia. The excess mortality among miners was due mainly to ischemic heart disease (IHD); 44 were observed, the expected number was 22.1, based on the general male population, and the North Karelian expected number was 31.2 (p less than .05). Of the 44 miners who died from IHD, 20 were drillers or chargers exposed to nitroglycerin in dynamite charges, but also to several simultaneous stress factors including PAHs, noise, vibration, heavy work, accident risk, and working alone. Altogether 16 tumors were observed in the cohort. Ten of these were lung cancers, the expected number being 4.3. Miners who had died from lung cancer were 35-64 years old, and had entered mining work between 1954 and 1960. Five of the ten lung cancer cases came from the zinc mine (1.7 expected). Three of them were conductors of diesel-powered ore trains.

  14. Platinum metals magmatic sulfide ores.

    PubMed

    Naldrett, A J; Duke, J M

    1980-06-27

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. PMID:17796685

  15. Ore genesis of the Weibao lead-zinc district, Eastern Kunlun Orogen, China: constrains from ore geology, fluid inclusion and isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Fang, Jing; Chen, Huayong; Zhang, Li; Zheng, Yi; Li, Dengfeng; Wang, Chengming; Shen, Dengliang

    2015-07-01

    The Weibao lead-zinc district, composed by two deposits named the East Weibao deposit and the West Weibao deposit, respectively, is located in the Qimantagh area, Eastern Kunlun Orogen. Although both controlled by skarn alternation and experienced similar mineralization processes, the East Weibao deposit is dominated by massive ores, while the West Weibao deposit is characterized by banded ores. The ore-forming processes of both the deposits can be divided into four stages including prograde skarn stage, retrograde skarn stage, sulfide stage and carbonate stage. Three types of fluid inclusions, i.e., pure CO2 fluid inclusion (PC-type), CO2-bearing fluid inclusion (C-type) and aqueous types (W-type), have been identified in quartz, calcite and sphalerite from different stages. Noteworthily, only sulfide stage of the East Weibao deposit contains carbonic fluid inclusions, whereas only aqueous fluid inclusions were observed in sulfide stage of the West Weibao deposit. The CO2-rich and aqueous-type fluid inclusions in sulfide stage of the East Weibao deposit were homogenized at temperatures between 263 and 424 °C, concentrating at 360-400 °C, with salinities ranging between 3.2 and 13.6 wt% NaCl eqv.; the W-type fluid inclusions in sulfide stage of the West Weibao deposit were homogenized at temperatures between 228 and 381 °C, concentrating at 280-340 °C, with salinities between 1.6 and 9.0 wt% NaCl eqv.; and the aqueous-type fluid inclusions in carbonate stage in both deposits were homogenized at temperatures between 115 and 336 °C, concentrating at 200-240 °C, with salinities between 0.2 and 5.9 wt% NaCl eqv. The ore-forming fluid in sulfide stage at the East Weibao deposit yielded calculated and δ18D values of 4.2 to 5.6 and -88 to -83 ‰, respectively. The results are 8.8 to 10.8, -99 to -92 ‰ for the sulfide stage at the West Weibao deposit and -1.0 to -0.2, -50 to -45 ‰ for carbonate stages in both deposits. The lead isotopic ratios of sulfide

  16. [Biooxidation of a Double-Refractory Gold-Bearing Sulfide Ore Concentrate].

    PubMed

    Bulaev, A G; Kanaeva, Z K; Kanaev, A T; Kondrat'eva, T F

    2015-01-01

    The efficiency of biooxidation for treatment of a double-refractory gold-bearing sulfide ore concentrate from the Bakyrchik deposit (East Kazakhstan) was defined. The experiments were conducted in two different modes, i.e., with the standard liquid medium and the medium imitating the chemical composition of the Bakyrchik deposit groundwater and containing high concentrations of sodium, magnesium, and chloride. The concentrate contained 17.5% of organic carbon, 6% of pyrite and 13% arsenopyrite. Gold content was 57.5 g t@-1@. Direct gold recovery by cyanidation was very low (2.8%). While biooxidation was efficient in both cases (approximately 90% of sulfide sulfur was oxidized), the efficiency of cyanidation was low (39 and 32%, respectively). This fact suggests high efficiency of biooxidation is insufficient for efficient treatment of double-refractory gold-bearing sulfide ore concentrates. PMID:27169245

  17. Helium isotopes and mineralogy of hydrothermal ores from the Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Ooki, M.; Takahata, N.; Sano, Y.; Kagoshima, T.; Ishibashi, J.

    2012-12-01

    It is known that 3He/4He ratio of the typical mid-ocean ridge basalt (MORB) is 8±1.5 times higher than the atmospheric ratio, representative of the upper mantle. Similar high ratios have been observed in volcanic geothermal systems of subduction zones. To understand the origin of submarine hydrothermal fluids, we have measured helium isotopic ratios of fluid inclusions in hydrothermal ore deposits from the Okinawa Trough. Hydrothermal ore samples were collected during NT11-20 expedition using ROV Hyper-Dolphin(JAMSTEC), from Minami-Ensei Knoll, Yoron Knoll and Hatoma Knoll. Approximately 1 g of the ore sample picked up and put it in a stainless-steel crusher with a stainless-steel ball. Each ore sample was baked at approximately 200 degrees for 12 hours under vacuum to remove water and atmospheric components absorbed on surface. When the crusher was shaken up and down, the minerals in ores were crushed by the stainless-steel ball. Thus, gases in fluid inclusions were introduced into a vacuum line. These gases were purified, and helium-4 (4He) intensity and 3He/4He ratio were measured by a noble gas mass spectrometer, 4He/20Ne ratio and gas abundance (helium and neon) were measured by a quadrupole-based mass spectrometric system. Measured 3He/4He ratios of the most samples display obviously higher values than the atmospheric ratio (5~8Ratm). These values are slightly lower than or the same as that of MORB ratio. Conversely, measured 4He/20Ne ratios of samples show closer values to atmosphere than MORB. We discuss the fluid sources of Minami-Ensei Knoll, Yoron Knoll and Hatoma Knoll based on the helium isotopes as well as mineralogical features of hydrothermal ore samples.

  18. Mineralogical characterization of the Nkamouna Co-Mn laterite ore, southeast Cameroon

    NASA Astrophysics Data System (ADS)

    Lambiv Dzemua, G.; Gleeson, S. A.; Schofield, P. F.

    2013-02-01

    The Nkamouna property is an oxide laterite deposit developed on serpentinized peridotite in southeast Cameroon. It is enriched in Co and Mn, has sub-economic Ni grades and will be mined primarily for Co. The ore zone is ca. 10 m thick and comprises the lower breccia (˜3 m thick) and ferralite (7-8 m thick) units sandwiched between an 8-m-thick ferricrete overburden and a barren hydrated Mg-silicate saprolite. The ore mineral assemblage includes Mn oxyhydroxides, magnetite, maghemite, ferritchromite, goethite, hematite, kaolinite and gibbsite. Lithiophorite is the most common Mn mineral and is the main host of Co, Mn and a significant proportion of Ni. It occurs as coatings in pores and on other mineral grains and as concretions and impregnations in the matrix. It is invariably associated with gibbsite in the lower breccia and with magnetite and ferritchromite in the ferralite. Although ore in the lower breccia is volumetrically less important than the ferralite, it has the highest grade and Co/Ni ratio. The lithiophorite in the ore zone is authigenic, and its formation was enhanced by influx of Al3+ from the overlying ferricrete. Magnetite and ferritchromite in the ferralite are relicts and contributed to mineralization by enhancing the permeability of the ferralite and providing substrates for the precipitation of the Mn oxyhydroxides. The structure and mode of occurrence of the lithiophorite makes Nkamouna ore amenable to physical beneficiation, producing a concentrate with Co grades 2.3-4.5 times higher than the run-of-mine ore.

  19. Kizilcaören ore-bearing complex with carbonatites (northwestern Anatolia, Turkey): Formation time and mineralogy of rocks

    NASA Astrophysics Data System (ADS)

    Nikiforov, A. V.; Öztürk, H.; Altuncu, S.; Lebedev, V. A.

    2014-02-01

    The results of isotope-geochronological and mineralogical studies of the rocks making up the Kizilcaören fluorite-barite-REE deposit, northwestern Anatolia, Turkey are discussed in the paper. The ore is a constituent of the subvolcanic complex localized in a large fault zone. The complex combines (from earlier to later rocks): (1) phonolite and trachyte stocks, (2) carbonatite and carbonate-silicate dikelike bodies; and (3) fluorite-barite-bastnaesite ore in the form of thick homogeneous veins and cement in breccia. The K-Ar dating of silicate igneous rocks and carbonatites shows that they were formed in the Chattian Age of the Oligocene 25-24 Ma ago. Mineralogical observations show that the ore is the youngest constituent in the rock complex. Supergene alteration deeply transformed ore-bearing rocks, in particular, resulting in leaching of primary minerals, presumably Ca-Mn-Fe carbonates, and in cementation of the residual bastnaesitefluorite framework by Fe and Mn hydroxides. Most of the studied rocks contain pyrochlore, LREE fluorocarbonates, Nb-bearing rutile, Fe-Mg micas, and K-feldspar. The genetic features of the deposit have been considered. In general, the ore-bearing rock complex is compared in the set of rocks and their mineralogy and geochemistry with deposits of the Gallinas Mountains in the United States, the Arshan and Khalyuta deposits in the western Transbaikalia region, and Mushugai-Khuduk deposit in Mongolia. The Kizilcaören deposit represents a variant of postmagmatic mineralization closely related to carbonatite magmatism associated with alkaline and subalkaline intermediate rocks.

  20. Uranium-lead ages of apatite from iron oxide ores of the Bafq District, East-Central Iran

    NASA Astrophysics Data System (ADS)

    Stosch, Heinz-Günter; Romer, Rolf L.; Daliran, Farahnaz; Rhede, Dieter

    2011-01-01

    Iron oxide-apatite (IOA) deposits, often referred to as Kiruna-type iron ore deposits, are known to have formed from the Proterozoic to the Tertiary. They are commonly associated with calc-alkaline volcanic rocks and regional- to deposit-scale metasomatic alteration. In the Bafq District in east Central Iran, economic iron oxide-apatite deposits occur within felsic volcanic tuffs and volcanosedimentary sequences of Early Cambrian age. In order to constrain the age of formation of these ores and their relationship with the Early Cambrian magmatic event, we have determined the U-Pb apatite age for five occurrences in the Bafq District. In a 206Pb/238U vs. 207Pb/235U diagram, apatite free of or poor in inclusions of other minerals plots along the Concordia between 539 and 527 Ma with four out of five samples from one deposit clustering at the upper end of this range. For this deposit, we interpret this cluster to represent the age of apatite formation, whereas the spread towards younger ages may reflect either minor Pb loss or several events of IOA formation. Apatite with inclusions of monazite (±xenotime) yields disturbed systems with inclusions having developed after formation of the iron ore-apatite deposits, possibly as late as 130-140 Ma ago. Obtained apatite ages confirms that (IOA) and the apatite-rich rocks (apatites) of the Bafq district formed coevally with the Early Cambrian magmatic (-metasomatic) events.

  1. 40 CFR 440.20 - Applicability; description of the aluminum ore subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... aluminum ore subcategory. 440.20 Section 440.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Aluminum Ore Subcategory § 440.20 Applicability; description of the aluminum ore subcategory. The... an aluminum ore....

  2. 40 CFR 440.20 - Applicability; description of the aluminum ore subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... aluminum ore subcategory. 440.20 Section 440.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Aluminum Ore Subcategory § 440.20 Applicability; description of the aluminum ore subcategory. The... an aluminum ore....

  3. 40 CFR 440.20 - Applicability; description of the aluminum ore subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... aluminum ore subcategory. 440.20 Section 440.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Aluminum Ore Subcategory § 440.20 Applicability; description of the aluminum ore subcategory. The... an aluminum ore....

  4. AMT survey in the Outokumpu ore Belt, Eastern Finland

    NASA Astrophysics Data System (ADS)

    Lahti, Ilkka; Kontinen, Asko; Aatos, Soile; Smirnov, Maxim

    2015-04-01

    conductors indicated by airborne electromagnetic data and regional strike analysis of acquired impedance tensor data. Two-dimensional inversion was done jointly for TE, TM- and Tipper data using the inversion code by Rodi and Mackie (2001). Results are visualized as sounding curves, sections of electrical conductivity and induction vectors. Results show dipping and sub-horizontal conductors southeast of the Outokumpu town. One c. 1 km deep sub-horizontal conductor is verified by a drill hole located approximately 8 km from the town. Gently eastwards dipping conductor was detected in the Miihkali serpentinite area. Conductors are absent in the uppermost ~ 7 km below the Sotkuma gneisses, which consequently represent rather a uplifted fault block than a thrust sheet of the Archaean basement rocks, thus resolving an old debate concerning the crustal structure at Sotkuma. In addition to AMT, high resolution seismic and airborne ZTEM surveys have been recently carried out in the study area providing a good opportunity to compare results from different deep penetrating geophysical methods. References Peltonen, P., Kontinen, A., Huhma, H. and Kuronen, U. 2008. Outokumpu revisited: New mineral deposit model for the mantle peridotite-associated Cu-Co-Zn-Ni-Ag-Au sulphide deposits: Ore Geology Reviews, 33, no. 3-4, 559-617. Rodi, W. and Mackie, R. 2001. Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion. Geophysics, 66, 174-187.

  5. Investigation of the wastes of chromium ore concentration for use as raw material in the manufacture of refractories

    SciTech Connect

    Antonov, G.I.; Yakobchuk, L.M.; Prokudin, V.Y.

    1994-09-01

    A complex investigation of wastes of the concentration of chromium ores of the Kempirsaiskoe deposit has demonstrated that they are similar to serpentinites as regards their composition and behavior in roasting. These wastes can be used as magnesia-silicate raw materials for the production of refractories.

  6. Alteration and ore distribution in the Proterozoic Mines Series, Tenke-Fungurume Cu-Co district, Democratic Republic of Congo

    NASA Astrophysics Data System (ADS)

    Fay, I.; Barton, M. D.

    2012-06-01

    Two sediment-hosted stratiform Cu-Co deposits in the Tenke-Fungurume district of the Central African Copperbelt were examined to evaluate the alteration history of the ore-hosting Mines Series and its implications for ore distribution and processing. Core logging and petrography, focused on lithology and timing relationships, outlined a complex alteration sequence whose earliest features include formation of anhydrite nodules and laths, followed by precipitation of dolomite. Later alteration episodes include at least two silica introductions, accompanied by or alternating with two dolomite introductions into the existing gangue assemblages. One introduction of Cu-Co sulfides accompanied the last episode of dolomite alteration, overprinting an earlier generation of ore whose gangue association was unidentifiable. Sulfides and some carbonates were subsequently modified by supergene oxidation, transport, and reprecipitation to 100-200 m depth. Present-day ore distribution resulted from these successive processes. Ore is concentrated in two shale-dominated units on either side of a cavernous silicified dolomite, which is interpreted as the main conduit for the mineralizing fluids. Sulfide ores precipitated at the redox or sulfidation contacts between this dolomite and the shales. Later, supergene fluids dissolved and moved some of the metals, redepositing them as oxides and carbonates. Solubility differences between Cu and Co in supergene conditions caused them to precipitate separately. Thus, modern ore distribution at Tenke-Fungurume results both from original hypogene lithology- and contact-related precipitation and from supergene oxidation, transport, and Cu-Co decoupling. The supergene fluid flow also redistributed gangue minerals such as dolomite, which has an economically important influence on the processing costs of supergene ores.

  7. CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING OVER IRON ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING OVER IRON ORE CARS TOWARDS CLEVELAND BULK TERMINAL BUILDINGS. LOOKING SOUTH. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  8. CONTEXT VIEW SHOWING MODERN TRACKS PASSING UNDER HULETTS AND ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW SHOWING MODERN TRACKS PASSING UNDER HULETTS AND ORE YARD. LOOKING NORTHEAST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  9. AERIAL OVERVIEW, LOOKING NORTH, WITH FORMER TCIUS STEEL ORE MINE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AERIAL OVERVIEW, LOOKING NORTH, WITH FORMER TCI-US STEEL ORE MINE HEADQUARTERS (BOTTOM) AND SUPERINTENDENT'S AND FOREMAN HOUSING ALONG MINNESOTA AVENUE AT CREST OF RED MOUNTAIN (TOP LEFT). - Muscoda Red Ore Mining Community, Bessemer, Jefferson County, AL

  10. CONTEXT VIEW ACROSS ORE YARD AT MODERN SELFUNLOADING SHIP UNLOADING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW ACROSS ORE YARD AT MODERN SELF-UNLOADING SHIP UNLOADING IN FRONT OF HULETTS. LOOKING SOUTHWEST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  11. CONTEXT VIEW ACROSS ORE YARD AT MODERN SELFUNLOADING BOOM IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW ACROSS ORE YARD AT MODERN SELF-UNLOADING BOOM IN FRONT OF HULETTS. LOOKING SOUTHWEST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  12. 3. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO WEST. - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  13. 1. VIEW TO SOUTH (RETAINING WALL OF ORE RECEIVING PLATFORM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW TO SOUTH (RETAINING WALL OF ORE RECEIVING PLATFORM TO LEFT). - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  14. 2. VIEW TO NORTHEAST (ORE RECEIVING PLATFORM OUT OF VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW TO NORTHEAST (ORE RECEIVING PLATFORM OUT OF VIEW TO RIGHT). - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  15. 4. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO EAST. - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  16. 7. VIEW OF CARRIE No. 3 AND No. 4 ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW OF CARRIE No. 3 AND No. 4 ORE BRIDGE, ORE YARD AND FURNACES FROM THE HOT METAL BRIDGE. - U.S. Steel Homestead Works, Blast Furnace Plant, Along Monongahela River, Homestead, Allegheny County, PA

  17. 32. INTERIOR VIEW LOOKING NORTH ON THE ORE BREAKER LEVEL. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. INTERIOR VIEW LOOKING NORTH ON THE ORE BREAKER LEVEL. THE ORE BREAKER, A BLAKE JAW CRUSHER, IS IN THE BOX IN THE LEFT OF THE PHOTOGRAPH, THE ORE TO BE BROKEN IS FED INTO THE OPENING ON THE FLOOR AND NEXT TO ORE BREAKER BOX. THE GRIZZLY BARS ARE ON THE RIGHT AND THE PULLEYS FROM THE POWER SYSTEM ARE OVERHEAD. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

  18. Placement Of O-Rings In Solid Rocket Booster

    NASA Technical Reports Server (NTRS)

    Wood, Charles

    1991-01-01

    Brief report proposes to modify placement of O-ring seals in joints of Solid Rocket Booster of Space Shuttle. Modified joint and seal essentially "inside-out" version of old joint and seal. O-rings placed between outer side of tang and clevis. Joint rotation pushes tang harder against O-rings, thereby making even tighter seal. Proposal derived from analysis of Space Shuttle Challenger disaster, attributed to failure of these O-ring seals.

  19. Thermal Barrier For Vented O-Ring Seal

    NASA Technical Reports Server (NTRS)

    Schick, H.; Shadlesky, Philip S.; Perry, Mark C.; Ketner, Donald M.; Salita, Mark

    1992-01-01

    Barrier allows gases to seat seal without damaging it. Ring of tungsten-wire mesh forms protective barrier between hot, pressurized combustion gases and O-rings. Mesh cools and depressurizes gases so they safely push on and thereby help to seat primary O-ring or secondary O-ring if primary O-ring fails to form seals. Barrier devised for use in rocket motor. Potential terrestrial applications includes aircraft engines, furnaces, and ducts carrying hot gases.

  20. Fluid inclusion characteristics and geological significance of the Dajinshan W-Sn polymetallic deposit in Yunfu, Guangdong Province

    NASA Astrophysics Data System (ADS)

    Yu, Zhangfa; Chen, Maohong; Zhao, Haijie

    2015-05-01

    The Dajinshan tungsten-tin polymetallic deposit is a quartz-vein-type ore deposit located in Western Guangdong Province. The ore bodies show a fairly simple shape and mainly occur as tungsten-tin polymetallic-bearing sulfide quartz veins, including quartz vein, quartz-greisens, and sulfide quartz veins, and their distribution is spatially related to Dajinshan granitoids. The formation of the deposit experienced three stages: a wolframite-molybdenite-quartz stage, a wolframite-cassiterite-sulfide-quartz stage, and a fluorite-calcite-carbonate stage. Based on detailed petrographic observations, we conducted microthermometric and Raman microspectroscopic studies of fluid inclusions formed at different ore-forming stages in the Dajinshan tungsten-tin polymetallic deposit, identifying four dominant types of fluid inclusions: aqueous two-phase inclusions, CO2-bearing inclusions, solid or daughter mineral-bearing inclusions, and gas-rich inclusions. The gas compositions of ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit are mostly CO2, CH4, and H2O. The hydrogen, oxygen, and sulfur isotopic data imply that the ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit were mainly derived from magmatic fluids, mixed with meteoric water in the ore-formation process. These results indicate that the fluid mixing and boiling led to the decomposition of the metal complex in ore-forming fluids and ore deposition.

  1. 17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN BUILT IN 1911-1912, THIS WAS THE LARGEST ORE-UNLOADING DOCK ON THE GREAT LAKES. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  2. 29. ORE DOCK, LOOKING WEST; AT WORK UNLOADING THE 'GEORGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. ORE DOCK, LOOKING WEST; AT WORK UNLOADING THE 'GEORGE M. HUMPHREY'S' CARGO OF 25,000. TONS OF ORE. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  3. CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING OVER IRON ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING OVER IRON ORE CARS TOWARDS WESTERN SIDE OF CLEVELAND BULK TERMINAL BUILDINGS AND A SELF-UNLOADING IRON ORE SHIP AT DOCK. LOOKING SOUTHWEST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  4. 18. VIEW OF CRUDE ORE BINS FROM WEST. WEST CRUDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. VIEW OF CRUDE ORE BINS FROM WEST. WEST CRUDE ORE BIN AND TRESTLE FROM TWO JOHNS TRAMLINE TO SOUTH, CRUDE ORE BIN IN FOREGROUND. MACHINE SHOP IN BACKGROUND. THE TRAM TO PORTLAND PASSED TO NORTH OF MACHINE SHOP. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  5. 3. EAGLE MILL, DETAIL OF CRUDE ORE BIN FROM NORTH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. EAGLE MILL, DETAIL OF CRUDE ORE BIN FROM NORTH, c. 1908-10. SHOWS EXPOSED CRUSHER HOUSE IN FRONT OF (SOUTH) CRUDE ORE BIN AND SNOW SHED ADDED OVER TRAM TRACKS. NOTE LACK OF EAST OR WEST CRUDE ORE BINS. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  6. 6. Looking west showing top of dock: steaming frozen ore ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Looking west showing top of dock: steaming frozen ore which had been put in pockets in December 1959, May 6, 1990. Photographer: unknown - Marquette Ore Dock No. 6, Ore Dock, On pilings in Marquette City Lower Harbor, Marquette, Marquette County, MI

  7. Rebound Of Previously Compressed O-Ring

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1988-01-01

    Report presents theoretical and experimental analysis of relaxation characteristics of O-ring of vinylidene fluoride/hexafluoropropylene copolymer of same composition used in solid rocket boosters on Space Shuttle flight 51-L. Study covers range of temperatures from 10 to 120 degree F. Presents one-dimensional mathematical model of response provided for both elastic response and creep.

  8. Ore Melting and Reduction in Silicomanganese Production

    NASA Astrophysics Data System (ADS)

    Ringdalen, Eli; Gaal, Sean; Tangstad, Merete; Ostrovski, Oleg

    2010-12-01

    The charge for silicomangansese production consists of manganese ore (often mixed with ferromanganese slag) dolomite or calcite, quartz, and in some cases, other additions. These materials have different melting properties, which have a strong effect on reduction and smelting reactions in the production of a silicomanganese alloy. This article discusses properties of Assman, Gabonese, and Companhia Vale do Rio Doce (CVRD) ores, CVRD sinter and high-carbon ferromanganese (HC FeMn) slag, and their change during silicomanganese production. The melting and reduction temperatures of these manganese sources were measured in a carbon monoxide atmosphere, using the sessile drop method and a differential thermal analysis/thermogravimetric analysis. Equilibrium phases were analyzed using FACTSage (CRCT, Montreal, Canada and GTT, Aachen, Germany) software. Experimental investigations and an analysis of equilibrium phases revealed significant differences in the melting behavior and reduction of different manganese sources. The difference in smelting of CVRD ore and CVRD sinter was attributed to a faster reduction of sinter by the graphite substrate and carbon monoxide. The calculation of equilibrium phases in the reduction process of manganese ores using FACTSage correctly reflects the trends in the production of manganese alloys. The temperature at which the manganese oxide concentration in the slag was reduced below 10 wt pct can be assigned to the top of the coke bed in the silicomanganese furnace. This temperature was in the range 1823 K to 1883 K (1550 °C to 1610 °C).

  9. Sources of ores of the ferroalloy metals

    USGS Publications Warehouse

    Burchard, E.F.

    1933-01-01

    Since all steel is made with the addition of alloying elements, the record of the metallic raw materials contributory to the steel industry would be far from complete without reference to the ferroalloy metals. This paper, therefore, supplements two preceding arvicles on the sources of our iron ores. The photographs, with the exception of those relating to molybdenum and vanadium, are by the author.

  10. Energy conservation during the smelting of ores

    SciTech Connect

    Barber, J. C.

    1985-07-16

    The invention discloses processes for preparing matched sizes of electric furnace feed materials. With the matched sizes, components of the feed mixture do not separate inside the furnace and this decreases the electric energy for smelting. Preparation of matched sizes of materials is made possible by low-temperature agglomeration followed by drying to indurate the agglomerates. Fuel requirements for induration are substantially reduced, and environmental problems associated with high-temperature agglomeration are eliminated. Phosphate ores can be agglomerated and simultaneously the ores are upgraded by increasing the P/sub 2/O/sub 5/ content. Unbeneficiated phosphate ores heretofore considered unsuited for smelting can be used as phosphate sources for the production of phosphorus. A combustible gas consisting mainly of carbon monoxide and hydrogen is generated when ores are smelted. Processes are disclosed for cleaning the gas to permit it to be burned in a facility for the cogeneration of electric energy. At phosphorus furnaces the potential energy in the gas is equal to about 65 percent of the electric energy used in smelting; consequently, the net electric energy consumption can be substantially reduced by operation of a cogeneration facility.

  11. PROCESS OF RECOVERING URANIUM FROM ITS ORES

    DOEpatents

    Galvanek, P. Jr.

    1959-02-24

    A process is presented for recovering uranium from its ores. The crushed ore is mixed with 5 to 10% of sulfuric acid and added water to about 5 to 30% of the weight of the ore. This pugged material is cured for 2 to 3 hours at 100 to 110 deg C and then cooled. The cooled mass is nitrate-conditioned by mixing with a solution equivalent to 35 pounds of ammunium nitrate and 300 pounds of water per ton of ore. The resulting pulp containing 70% or more solids is treated by upflow percolation with a 5% solution of tributyl phosphate in kerosene at a rate equivalent to a residence time of about one hour to extract the solubilized uranium. The uranium is recovered from the pregnant organic liquid by counter-current washing with water. The organic extractant may be recycled. The uranium is removed from the water solution by treating with ammonia to precipitate ammonium diuranate. The filtrate from the last step may be recycled for the nitrate-conditioning treatment.

  12. Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

    PubMed

    Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

    2014-11-01

    A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore.

  13. Paragenesis and conditions of formation of ore minerals from metalliferous breccia pipes, N. Arizona

    SciTech Connect

    Wenrich, K.J.; Pratt, L.M.

    1985-01-01

    Ore deposits within N. Arizona breccia pipes are currently being exploited for U, but at various times during the past century Cu, Pb, Zn, and Ag were mined. These pipes formed as solution-collapses within the Mississippian Redwall Ls and stopped upward through overlying strata. The principal ore minerals are: uraninite, chalcopyrite, chalcocite, tennantite-tetrahedrite, galena, sphalerite, millerite, gersdorffite, siegenite, and molybdenite. Common gangue minerals are marcasite, pyrite, barite, dolomite, calcite and quartz. Marcasite and pyrite appear to have formed prior to the ore minerals, followed closely by chalcopyrite. The Ni and Co phases also appear to be early: gersdorffite crystals are rimmed by later galena. Tennantite-tetrahedrite formed later than both galena and sphalerite; uraninite, the latest ore mineral, consisting fills interstices. Primary fluid inclusions in dolomite, quartz, and sphalerite show filling temperatures from 80 to 145/degree/C and high salinities, averaging 15 wt% NaCl (eq). Secondary inclusions in sphalerite have consistently higher filling temperatures from 105 to 173/degree/C, but similar salinities. Rock-Eval pyrolysis of pyrobitumen yields little or no volatile hydrocarbons (S/sub 1/=0-0.2 mg/gm), but large amounts of pyrolytic hydrocarbons (S/sub 2/=105-216 mg/gm). Temperatures of maximum pyrolytic yield are relatively low (424-430/degree/C), suggesting temperatures did not exceed 150/degree/C following pyrobitumen emplacement. Except for uraninite, the breccia pipes are similar to Mississippi Valley-type (MVT) deposits in mineralogy, fluid-inclusion filling temperatures and salinities, and associated organic material. Because MVT deposits do not host U minerals, a possible two-stage mineralization history of the pipes is suggested, the first by a MVT brine and perhaps a second forming the uraninite.

  14. 13. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN BUILT IN 1911-1912, THIS WAS THE LARGEST ORE-UNLOADING DOCK ON THE GREAT LAKES. THE DOCK FEATURED FOUR HULETT UNLOADERS, EACH WITH A BUCKET CAPACITY OF 17 TONS; A 15-TON CAPACITY ORE STOCKING AND REHANDLING BRIDGE; AND A ONE-MILLION-TON CAPACITY ORE STORAGE YARD. THE WILLIAM-SEAVER-MORGAN COMPANY OF CLEVELAND BUILT THE DOCK EQUIPMENT. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  15. Degradation Characteristics of O-rings on Highly Aged GIS

    NASA Astrophysics Data System (ADS)

    Minagawa, Tadao; Nagao, Eiichi; Tsuchie, Ei; Yonezawa, Hiroshi; Takayama, Daisuke; Yamakawa, Yutaka

    Owing to increasing number of highly aged GIS, the investigation of the remaining lifetimes of those systems are becoming more important. Because a lot of O-rings are used in GIS, the study of degradation mechanism and lifetime estimation method of O-ring is essential. In this paper, the information about O-ring degradation mechanism is described, and the statistical method for estimating the remaining lifetime of O-ring is proposed. The degradation of O-ring is mainly subject to chemical reactions triggered by oxygen. Because there are many factors influencing those chemical reactions, the dispersion of degradation rates of O-rings in GIS is very large. Consequently the statistical analysis is one of the effective techniques for lifetime estimation of O-rings in GIS.

  16. High-rate behaviour of iron ore pellet

    NASA Astrophysics Data System (ADS)

    Gustafsson, Gustaf; Häggblad, Hans-Åke; Jonsén, Pär; Nishida, Masahiro

    2015-09-01

    Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

  17. DETAIL VIEW OF LOWER TRAM TERMINAL, SECONDARY ORE BIN, CRUSHER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF LOWER TRAM TERMINAL, SECONDARY ORE BIN, CRUSHER FOUNDATION, AND BALL MILL FOUNDATIONS, LOOKING NORTH NORTHWEST. ORE FROM THE MINES WAS DUMPED FROM THE TRAM BUCKETS INTO THE PRIMARY ORE BIN UNDER THE TRAM TERMINAL. A SLIDING CONTROL DOOR INTRODUCED THE INTO THE JAW CRUSHER (FOUNDATIONS,CENTER). THE CRUSHED ORE WAS THEN CONVEYED INTO THE SECONDARY ORE BIN AT CENTER LEFT. A HOLE IN THE FLOOR OF THE ORE BIN PASSED ORE ONTO ANOTHER CONVEYOR THAT BROUGHT IT OUT TO THE BALL MILL(FOUNDATIONS,CENTER BOTTOM). THIS SYSTEM IS MOST LIKELY NOT THE ORIGINAL SET UP, PROBABLY INSTALLED IN THE MINE'S LAST OCCUPATION IN THE EARLY 1940s. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

  18. The dilemma of the Jiaodong gold deposits: are they unique?

    USGS Publications Warehouse

    Goldfarb, Richard J.; Santosh, M.

    2013-01-01

    The ca. 126–120 Ma Au deposits of the Jiaodong Peninsula, eastern China, define the country's largest gold province with an overall endowment estimated as >3000 t Au. The vein and disseminated ores are hosted by NE- to NNE-trending brittle normal faults that parallel the margins of ca. 165–150 Ma, deeply emplaced, lower crustal melt granites. The deposits are sited along the faults for many tens of kilometers and the larger orebodies are associated with dilatational jogs. Country rocks to the granites are Precambrian high-grade metamorphic rocks located on both sides of a Triassic suture between the North and South China blocks. During early Mesozoic convergent deformation, the ore-hosting structures developed as ductile thrust faults that were subsequently reactivated during Early Cretaceous “Yanshanian” intracontinental extensional deformation and associated gold formation. Classification of the gold deposits remains problematic. Many features resemble those typical of orogenic Au including the linear structural distribution of the deposits, mineralization style, ore and alteration assemblages, and ore fluid chemistry. However, Phanerozoic orogenic Au deposits are formed by prograde metamorphism of accreted oceanic rocks in Cordilleran-style orogens. The Jiaodong deposits, in contrast, formed within two Precambrian blocks approximately 2 billion years after devolatilization of the country rocks, and thus require a model that involves alternative fluid and metal sources for the ores. A widespread suite of ca. 130–123 Ma granodiorites overlaps temporally with the ores, but shows a poor spatial association with the deposits. Furthermore, the deposit distribution and mineralization style is atypical of ores formed from nearby magmas. The ore concentration requires fluid focusing during some type of sub-crustal thermal event, which could be broadly related to a combination of coeval lithospheric thinning, asthenospheric upwelling, paleo-Pacific plate

  19. Occurence of ore metals in some terrestrial geothermal systems

    SciTech Connect

    Browne, P.

    1984-02-01

    Drilling programs and the study of active geothermal systems have shown that the reservoir rocks in many fields contain minor quantities of base and precious metals. Commonly, base-metal sulfides occur in the subsurface but, where present, Au, Ag, Hg, As, Tl and Sb rich precipitates deposit near, or at, the surface. Although in some fields (Geysers, Larderello, Tongonan) some of the ore minerals (and others) are relict, there is evidence that they are now depositing in a few systems. Recent work on active hydrothermal systems in New Zealand shows that: (1) Sphalerite, galena, chalcopyrite (forming veins and disseminated discrete crystals) plus rare pentlandite, cobaltite and arsenopyrite, occur at Broadlands, NZ. Rare quantities of base-metal sulfides also occur in cores and cuttings from the geothermal fields of Waiotapu, Kawerau, Tauhara, and Ngawha. Further, Kakimoto (1983) has identified cassiterite, native silver, and trace gold in cores from Tauhara, in the south-eastern part of the Wairakei field. Bore temperatures at the depths from which these minerals were recovered are mostly between 220/sup 0/ and 300/sup 0/C, but at Broadlands are locally as low as 120/sup 0/C. The host rocks are Quaternary calc-alkali, silicic lavas and pyroclastic rocks, andesites, dacite and deep Mesozoic greywackes and argillites; however, there is no obvious relationship between mineralization and stratigraphy, permeability or well output. The deposition of amorphous precious metal precipitates (Au, Ag, Hg, As, Sb, Tl) from hot springs and well discharges has taken place at Broadlands, Waiotapu and Rotokawa; it also occurs at Kawerau. Water discharging from Frying Pan Lake, Waimangu, is presently depositing siliceous sinter containing up to 4.1% tungsten.

  20. Petrographic-geochemical characteristics of granitoids and their epigenetic alteration products in paleovalley fields (Vitim uranium-ore site)

    NASA Astrophysics Data System (ADS)

    Kuznetsova, E. S.; Domarenko, V. A.; Matveenko, I. A.

    2016-09-01

    The study describes the results of the mineral and element composition of granitoids in basement and weathering crust of Khiagdinsk ore field in Vitim uranium ore site. It has been stated that granitoids in basement consist of leucocratic biotite granite of subalkaline group. The major rock-forming, accessory (apatite, zircon, sphene (titanite), magnetite, monazite, xenotime), and uranium-bearing minerals have been determined. Weathering crust is composed of unlithified or weakly lithified sediments, among which sandy and sandy medium gravel deposits have been distinguished in terms of mineralogical and granulometric texture. High radioactivity of granitoids was revealed in thorium-uranium basement and natural uranium. The combination of the specified factors presupposes that granitoids of Vitim uranium ore site may be a source of uranium in the fields of the paleovalley type.

  1. Pre-colombian mercury pollution associated with the smelting of argentiferous ores in the Bolivian Andes.

    PubMed

    Cooke, Colin A; Balcom, Prentiss H; Kerfoot, Charles; Abbott, Mark B; Wolfe, Alexander P

    2011-02-01

    The development of the mercury (Hg) amalgamation process in the mid-sixteenth century triggered the onset of large-scale Hg mining in both the Old and New Worlds. However, ancient Hg emissions associated with amalgamation and earlier mining efforts remain poorly constrained. Using a geochemical time-series generated from lake sediments near Cerro Rico de Potosí, once the world's largest silver deposit, we demonstrate that pre-Colonial smelting of Andean silver ores generated substantial Hg emissions as early as the twelfth century. Peak sediment Hg concentrations and fluxes are associated with smelting and exceed background values by approximately 20-fold and 22-fold, respectively. The sediment inventory of this early Hg pollution more than doubles that associated with extensive amalgamation following Spanish control of the mine (1574-1900 AD). Global measurements of [Hg] from economic ores sampled world-wide indicate that the phenomenon of Hg enrichment in non-ferrous ores is widespread. The results presented here imply that indigenous smelting constitutes a previously unrecognized source of early Hg pollution, given naturally elevated [Hg] in economic silver deposits.

  2. Genetic and biochemical effects induced by iron ore, Fe and Mn exposure in tadpoles of the bullfrog Lithobates catesbeianus.

    PubMed

    Veronez, Alexandra Caroline da Silva; Salla, Rômulo Victor; Baroni, Vinícius Dadalto; Barcarolli, Indianara Fernanda; Bianchini, Adalto; Dos Reis Martinez, Claudia Bueno; Chippari-Gomes, Adriana Regina

    2016-05-01

    For decades, the extraction of minerals has intensified in order to meet the demand of industry. Iron ore deposits are important sources of metals, such as iron (Fe) and manganese (Mn). The particulate ores can be dispersed during extraction, transport and storage, with potential to induce biological impacts. Amphibians are very sensitive to environmental stressors. Therefore, the present study aimed to assess the effects of iron ore, Fe and Mn exposure during the metamorphosis of Lithobates catesbeianus. Endpoints analyzed included morphological (biometrical and developmental analyses), whole body Fe and Mn concentration in, plasma ferritin concentration, erythrocyte DNA damage (measured through comet assay and micronucleus test) and liver activity of enzymes involved in oxidative status [glutathione S-transferase (GST) and catalase (CAT)]. Tadpoles were kept under control condition (no contaminant addition) or exposed to iron ore (3.79mg/L as fine particulate matter); Fe (nominal concentration: 0.51mg/L Fe as C10H12FeN2NaO8; Fe-EDTA); and Mn (nominal concentration: 5.23mg/L Mn as 4H2O.MnCl2) for 30 days. Virtually, no mortality was observed, except for one tadpole found dead in the iron ore treatment. However, tadpoles exposed to iron ore had longer tail than those kept under control conditions while tadpoles exposed to manganese chloride showed higher body length than control ones. Exposure to Fe and Mn induced a delay in tadpole metamorphosis, especially when these metals are presented not as a mixture (iron ore). Tadpoles exposed to iron ore had increased whole body Fe and Mn while those exposed to Fe and Mn accumulated each metal individually. Tadpoles exposed to any of the contaminants tested showed a significant increase in erythrocyte DNA damage and frequency of micronuclei. In addition, they showed higher liver GST activity respect with those kept under control conditions. Plasma ferritin concentration and liver CAT activity were higher only in tadpoles

  3. Genetic and biochemical effects induced by iron ore, Fe and Mn exposure in tadpoles of the bullfrog Lithobates catesbeianus.

    PubMed

    Veronez, Alexandra Caroline da Silva; Salla, Rômulo Victor; Baroni, Vinícius Dadalto; Barcarolli, Indianara Fernanda; Bianchini, Adalto; Dos Reis Martinez, Claudia Bueno; Chippari-Gomes, Adriana Regina

    2016-05-01

    For decades, the extraction of minerals has intensified in order to meet the demand of industry. Iron ore deposits are important sources of metals, such as iron (Fe) and manganese (Mn). The particulate ores can be dispersed during extraction, transport and storage, with potential to induce biological impacts. Amphibians are very sensitive to environmental stressors. Therefore, the present study aimed to assess the effects of iron ore, Fe and Mn exposure during the metamorphosis of Lithobates catesbeianus. Endpoints analyzed included morphological (biometrical and developmental analyses), whole body Fe and Mn concentration in, plasma ferritin concentration, erythrocyte DNA damage (measured through comet assay and micronucleus test) and liver activity of enzymes involved in oxidative status [glutathione S-transferase (GST) and catalase (CAT)]. Tadpoles were kept under control condition (no contaminant addition) or exposed to iron ore (3.79mg/L as fine particulate matter); Fe (nominal concentration: 0.51mg/L Fe as C10H12FeN2NaO8; Fe-EDTA); and Mn (nominal concentration: 5.23mg/L Mn as 4H2O.MnCl2) for 30 days. Virtually, no mortality was observed, except for one tadpole found dead in the iron ore treatment. However, tadpoles exposed to iron ore had longer tail than those kept under control conditions while tadpoles exposed to manganese chloride showed higher body length than control ones. Exposure to Fe and Mn induced a delay in tadpole metamorphosis, especially when these metals are presented not as a mixture (iron ore). Tadpoles exposed to iron ore had increased whole body Fe and Mn while those exposed to Fe and Mn accumulated each metal individually. Tadpoles exposed to any of the contaminants tested showed a significant increase in erythrocyte DNA damage and frequency of micronuclei. In addition, they showed higher liver GST activity respect with those kept under control conditions. Plasma ferritin concentration and liver CAT activity were higher only in tadpoles

  4. Preliminary reduction of oxidized nickel ores

    NASA Astrophysics Data System (ADS)

    Pakhomov, R. A.; Starykh, R. V.

    2014-11-01

    The laws of gas reduction of oxidized nickel ores (ONOs) are studied. The theoretical prerequisites of the selective reduction of ONO nickel, which are based on the difference between the oxygen partial pressures over the NiO-Ni and FeO-Fe systems, are discussed. The effect of the oxygen partial pressure during reducing roasting of ONOs of ferruginous and magnesia types on the reduction parameters and the quality of the ferronickel formed upon subsequent melting of cinders is experimentally investigated. The optimum conditions of preliminary gas reduction of ONOs are determined. Melting of the cinder of reducing roasting leads to the formation of nickel-rich ferronickel (20-50 wt % Ni for various types of ores) upon the extraction of nickel into ferronickel of >95%, which substantially exceeds the parameters of the existing commercial processes.

  5. Geodynamically unusual settings of sedimentary rock and ore formation due to tectonic-decompression effects

    SciTech Connect

    Goryainov, P.M.

    1984-05-01

    The traditional views of terrigenous rocks as products of classical sedimentary cycle, ''mobilization-transport-deposition,'' are not universal. Detrital rocks are sometimes formed due to flaking and fracturation of rocks of rising blocks. The process is produced by tectonic-decompression mechanisms - the origination of a gradient of excessive stress and its discharge. It is incorrect to classify rocks created by this phenomenon with weathering crusts. The origins of certain terrigenous rocks, as well as products of low-temperature chemical processing, are connected with deep-volume decompression (brecciation, stockwork formation, formation of pipes and columns of igneous rocks, and chamber pegmatite and karst formation). The ore concentrations associated with such entities and appearing as stratiform deposits are most likely not exogenous, but they complete the endogenous history of the block concerned. The means and methods tested on typical endogenous deposits may therefore prove valuable in predicting certain varieties of stratiform deposits.

  6. Trace and rare earth elements fractionation in volcanic- and sediment-hosted Mn ores: a study case of Sardinia (western Italy).

    NASA Astrophysics Data System (ADS)

    Sinisi, Rosa

    2015-04-01

    It is widely accepted that, regardless of the geological environment (continental, marine or hydrothermal), the occurrences of clay minerals and/or mineral phases with clay-type crystal structure (as zeolites and Mn-oxides), play a key role in the trace elements and REEs uptake processes. The REE resources are produced mostly from ion-adsorption type REE deposits of southern China that are formed by weathering of granitic rocks and subsequent chemical adsorption of REE on clay minerals. A significant group of minerals with a high metal uptake capacity is represented by Mn oxides. Their "tunnel" structure, in fact, allows both the absorption (inside the minerals) and adsorption (outside the minerals) of cations and anions producing metal accumulations with economic and environmental significance. However, the ores, mainly that forming within sedimentary environment, often have impurities due to presence of minerals unrelated to mineralization. These minerals can significantly alter the compositional features of the ores and suggest misleading conclusions. In Sardinia (Italy, western Mediterranean), Mn-oxide mineralizations occur and recently their origin has been discussed and identified (Sinisi et al. 2012). In this study the mineralogical and chemical compositions of the Sardinian sediment-hosted and volcanic-hosted Mn-ore are exhibit exploring the possibility that they can represent exploitable trace and REE mineralizations. High contents of metals characterize these Mn deposits. Besides some trace elements (Ni, Cr, Zn, Cu, As, Pb, and U) that commonly typify the Mn oxi-hydroxide ores, all rare earth elements showed high concentrations in the Sardinian deposits, comparable to those of the main actually exploited REE sinks. For this reason, a simple statistical data treatment (R-mode Factor Analysis) was performed on fifteen and nineteen samples of sediment-hosted and volcanic-hosted Mn ore respectively, in order to identify both the mineral phases trapping trace

  7. Iron ore weathering potentials of ectomycorrhizal plants.

    PubMed

    Adeleke, R A; Cloete, T E; Bertrand, A; Khasa, D P

    2012-10-01

    Plants in association with soil microorganisms play an important role in mineral weathering. Studies have shown that plants in symbiosis with ectomycorrhizal (ECM) fungi have the potential to increase the uptake of mineral-derived nutrients. However, it is usually difficult to study many of the different factors that influence ectomycorrhizal weathering in a single experiment. In the present study, we carried out a pot experiment where Pinus patula seedlings were grown with or without ECM fungi in the presence of iron ore minerals. The ECM fungi used included Pisolithus tinctorius, Paxillus involutus, Laccaria bicolor and Suillus tomentosus. After 24 weeks, harvesting of the plants was carried out. The concentration of organic acids released into the soil, as well as potassium and phosphorus released from the iron ore were measured. The results suggest that different roles of ectomycorrhizal fungi in mineral weathering such as nutrient absorption and transfer, improving the health of plants and ensuring nutrient circulation in the ecosystem, are species specific, and both mycorrhizal roots and non-mycorrhizal roots can participate in the weathering process of iron ore minerals.

  8. Mineral deposits of Central America, with a section on manganese deposits of Panama

    USGS Publications Warehouse

    Roberts, Ralph Jackson; Irving, Earl Montgomery; Simons, F.S.

    1957-01-01

    The mineral deposits of Central America were studied between 1942 and 1945, in cooperation with the United States Department of State and the Foreign Economic Administration. Emphasis was originally placed on the study of strategic-mineral deposits, especially of antimony, chromite, manganese, quartz, and mica, but deposits of other minerals that offered promise of significant future production were also studied. A brief appraisal of the base-metal deposits was made, and deposits of iron ore in Honduras and of lead and zinc ores in Guatemala were mapped. In addition, studies were made of the regional geology of some areas, data were collected from many sources, and a new map of the geology of Central America was compiled.

  9. Manganese oxides and associated minerals as constituents of dispersed mineralization of metasomatic rocks in the Dukat ore field

    NASA Astrophysics Data System (ADS)

    Filimonova, L. G.; Sivtsov, A. V.; Trubkin, N. V.

    2010-08-01

    Lithiophorite and coronadite—varieties of vernadite and todorokite—make up finely dispersed colloform mixtures along with minor grains and nanoparticles of aluminosilicates and ore minerals in metasomatic rocks of the Dukat ore field, which were formed in local areas of fluid and hydrothermal-solution discharge at the upper level of the ore-forming system. Fe-vernadite associates with feroxyhyte, magnetite, apatite, K-feldspar, native silver, and acanthite in greisenized granitoids and with epidote, cerianite, plattnerite, and Fe-chlorite in quartz-garnet-chlorite propylites. Todorokite with high Pb, Tl, and Sn contents associates with epidote, albite, bitumen, and native silver in quartz-epidote-chlorite propylites. Al-vernadite, coronadite, and lithiophorite associate with opal, kaolinite, Fe-chlorite, zincite, uraninite, native silver, and acanthite in argillisites. These data allowed us to estimate the conditions of manganese accumulation in the epithermal ore-forming system and deposition conditions of Mn-rich, finely dispersed mineral mixtures in mineralized zones hosted in metasomatic rocks of the ore field.

  10. Main types of gold ore forming systems and their relationship with the paleogeodynamic settings on the Taimyr Peninsula and the Severnaya Zemlya Archipelago

    NASA Astrophysics Data System (ADS)

    Proskurnin, Vasiliy; Anatoly, Gavrish; Aleksandra, Bagaeva; Petrushkov, Boris; Shneider, Alexey; Saltanov, Vasily; Stepunina, Maria; Proskurnina, Alina

    2014-05-01

    carbonate-terrigenous carbonaceous deposits and tectonic-hydrothermal (propylite-beresite) in plutonic-volcanic complexes (Malinovsky, Gagarinsky, Svetlinsky ore zones). Late Paleozoic - Early Mesozoic manifestations of plutonic - hydrothermal ore-forming systems are associated: for gold - (sulphide) - quartz formation - with development of early deuterogenic diorite- granitoids of the diorite-granodiorite formation (I - type) and confinement to the remote from granites exocontact areas of greenschist facies (Osnovnoy Creek, Lagerninsky ore zones); for gold-bearing copper-molybdenum-porphyry formation - with development of late deuterogenic subalkaline granites of A-type and confinement to the apical areas of massifs (Oleninsky, Shirokinsky, Uboyninsky ore clusters).

  11. Metallogenic events and tectonic setting of the Duobaoshan ore field in Heilongjiang Province, NE China

    NASA Astrophysics Data System (ADS)

    Hao, Yu-Jie; Ren, Yun-Sheng; Duan, Ming-Xin; Tong, Kuang-Yin; Chen, Cong; Yang, Qun; Li, Chao

    2015-01-01

    The Duobaoshan ore field, a major center of metal production in Northeast China, is located in the northeast of the Xing'an-Mongolia Orogenic Belt (the eastern part of the Central Asian Orogenic Belt) and within the northern Greater Xing'an Mountains. Several types of ore deposits are mined in the Duobaoshan region, including the Duobaoshan and Tongshan porphyry copper-molybdenum deposits, the Sankuanggou skarn iron-copper deposit, and the Zhengguang epithermal gold deposit. Zircon grains from the Tongshan granodiorite and porphyritic granite yield laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb weighted mean ages of 475.9 ± 0.8 Ma and 230.9 ± 0.9 Ma to 240.7 ± 0.8 Ma, respectively. The Re-Os isochron age of molybdenites from the Tongshan deposit is 473 ± 4 Ma. Because both field observations and petrographic analysis identified disseminated chalcopyrite, pyrite, and malachite in the porphyritic granite, the isotope dating indicates that the Tongshan deposit underwent at least two magmatic-mineralization events, during the Ordovician and the Triassic. Zircon grains from the metallogenic granodiorite of the Sankuanggou skarn deposit yield an age of 176.1 ± 0.3 Ma, and Re-Os dating of molybdenite gives an age of 173 ± 6 Ma, indicating a Jurassic event. Based on previous research and the new geochemical analysis presented in this study, it is inferred that the magmatism and mineralization of the Sankuanggou deposit were associated with the subduction of the Paleo-Pacific Plate. The Duobaoshan region has therefore experienced at least three major magmatic and mineralization events, during the Ordovician (470-480 Ma), the Triassic (230-240 Ma), and the Early Jurassic (170-180 Ma).

  12. Reactive flow models of the Anarraaq Zn-Pb-Ag deposit, Red Dog district, Alaska

    USGS Publications Warehouse

    Schardt, C.; Garven, G.; Kelley, K.D.; Leach, D.L.

    2008-01-01

    The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200??C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS- source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency). ?? Springer-Verlag 2008.

  13. Reactive flow models of the Anarraaq Zn-Pb-Ag deposit, Red Dog district, Alaska

    NASA Astrophysics Data System (ADS)

    Schardt, Christian; Garven, Grant; Kelley, Karen D.; Leach, David L.

    2008-09-01

    The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200°C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS- source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency).

  14. High REE and Y concentrations in Co-Cu-Au ores of the Blackbird district, Idaho

    USGS Publications Warehouse

    Slack, J.F.

    2006-01-01

    Analysis of 11 samples of strata-bound Co-Cu-Au ore from the Blackbird district in Idaho shows previously unknown high concentrations of rare earth elements (REE) and Y, averaging 0.53 wt percent ???REE + Y oxides. Scanning electron microscopy indicates REE and Y residence in monazite, xenotime, and allanite that form complex intergrowths with cobaltite, suggesting coeval Co and REE + Y mineralization during the Mesoproterozoic. Occurrence of high REE and Y concentrations in the Blackbird ores, together with previously documented saline-rich fluid inclusions and Cl-rich biotite, suggest that these are not volcanogenic massive sulfide or sedimentary exhalative deposits but instead are iron oxide-copper-gold (IOCG) deposits. Other strata-bound Co deposits of Proterozoic age in the North American Cordillera and elsewhere in the world may have potential for REE and Y resources. IOCG deposits with abundant light REE should also be evaluated for possible unrecognized heavy REE and Y mineralization. ?? 2006 by Economic Geology.

  15. Beryllium deposits of the western Seward Peninsula, Alaska

    USGS Publications Warehouse

    Sainsbury, C.L.

    1963-01-01

    Deposits of beryllium ore in the Lost River area of the western Seward Peninsula, Alaska, consist of replacement veins, pipes, and stringer lodes is limestone in a zone about 7 miles long and 2 to 3 miles wide which is faulted and intruded by dikes and stocks. The ores are remarkably alike and typically consist of the following minerals, in percent: fluorite, 45-65; diaspore, 5-10; tourmaline, 0-10; chrysoberyl, 3-10; white mica, 0-5; small amounts of hematite, sulfide minerals, manganese oxide, other beryllium minerals; and traces of minerals not yet identified. The ores generally are cut by late veinlets which are of the same mineralogy as the groundmass ore, or which consist of fluorite, white mica, and euclase. The ores are fine grained, and many of the individual mineral grains, except fluorite, are less than 1 mm in size. The beryllium content of bulk samples of ore ranges from 0.11 to 0.54 percent (0.31 to 1.50 percent BeO). High-grade nodules, composed principally of chrysoberyl, diaspore, fluorite, and mica, contain as much as 6 percent BeO. Geochemical reconnaissance has disclosed other areas of anomalous beryllium in stream sediments elsewhere on the Seward Peninsula, generally around biotite granites that have them associated with tin deposits; additional exploration probably will disclose other deposits.

  16. The utilisation of magnetic susceptibility as a vector toward mineralisation in common rock and ore forming minerals.

    NASA Astrophysics Data System (ADS)

    English, Matthew; Raub, Tim

    2015-04-01

    Aeromagnetic and ground magnetic surveys of mineral deposits and prospective terrain are a fundamental technique used in mining and economic geology. Inversion of survey data to source parameters (i.e., identification of ore zones) is often simplified by assuming a single, canonical or 'average' value for the magnetic susceptibility of each mappable unit. In some mineral deposits, canonical magnetic susceptibility values for several dominant ore and accessory minerals will be used to calculate mineral concentrations, 3-D distributions, etc. In general, magnetic susceptibility is widely recognised by economic geologists as a fundamental, easily-measured tool used to better understand the prospectivity of ore deposits. Despite this, the quantitative application of magnetic susceptibility, in context of detailed ore petrology, is still a developing field yet one with great potential. In order to assess to what extent, and in which systems, magnetic susceptibility is a vector toward mineralisation, we present aspects of an extensive database of single crystal and ore mineral aggregate samples. This reveals trends and magnitudes for several important rock-forming and ore-associated minerals during alteration, paragenesis, and enrichment. For example, current literature canonical values show that the magnetic susceptibility for pure quartz is strongly diamagnetic but ranges between -1.78x10-5 and -1.00x10-5 (k, vol. SI). However, metamorphic bull quartz and chrysoprase are commonly paramagnetic, with common values for chrysoprase as high as 2.11x10-3. In contrast, measurements from rose quartz samples are lower than those described for pure quartz with modal measurements as low as -2.08x10-5. Measurements for rock crystal quartz form a distribution best described by the canonical diamagnetic value of -1.40x10-5. Modelling should take into account that rock crystal quartz is rarely the best petrological analogue at deposit-scale or in a quartzose terrain. The difference

  17. Acid pre-treatment method for in situ ore leaching

    DOEpatents

    Mallon, R.G.; Braun, R.L.

    1975-10-28

    An acid leaching method is described for the recovery of a desired element from a subterranean rubblized body of primary ore containing the element and also having associated therewith a carbonate mineral wherein the rubblized ore body is flooded with an aqueous acidic solution in order to release carbon dioxide from the associated carbonate mineral. After a substantial portion of the available carbon dioxide is released and removed from the ore body, as by venting to the atmosphere, an oxidizing gas is introduced into the flooded, rubblized ore to oxidize the ore and form an acid leach solution effective in the presence of the dissolved oxidizing gas to dissolve the ore and cause the desired element to go into solution. The leach solution is then circulated to the surface where the metal values are recovered therefrom.

  18. Device For Testing Compatibility Of An O-Ring

    NASA Technical Reports Server (NTRS)

    Davis, Dennis D.

    1995-01-01

    Fixture designed for use in exposing compressed elastomeric O-ring or other ring seal to test fluid. Made of metal or plastic, with threaded recess into which O-ring placed. Opposite threaded end is opening through which test fluid introduced and placed in contact with O-ring. After exposure, compression set and swell or shrinkage of ring measured. Fixture set to compress ring by selected amount, providing for reproducible compression.

  19. 37. VIEW NORTH FROM EAST CRUDE ORE BIN TO CRUSHER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. VIEW NORTH FROM EAST CRUDE ORE BIN TO CRUSHER ADDITION AND CRUSHED OXIDIZED ORE BIN. VISIBLE ARE DINGS MAGNETIC PULLEY (CENTER), THE 100-TON STEEL CRUSHED UNOXIDIZED ORE BIN, AND UPPER PORTION OF THE STEPHENS-ADAMSON 25 TON/HR BUCKET ELEVATOR. THE UPPER TAILINGS POND LIES BEYOND THE MILL WITH THE UPPER TAILINGS DAM UNDER THE GRAVEL ROAD IN THE UPPER RIGHT CORNER. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  20. OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE BIN, LOOKING NORTHEAST. REMAINS OF A BLACKSMITH'S FORGE AND WORK CAN BE SEEN JUST BELOW THE ORE BIN (SEE CA-291-32 FOR DETAIL). ROCK FOUNDATIONS LOCATED JUST ABOVE THE ORE BIN AND ALONG THE FIRST RIDGELINE ARE TENT PADS. SEE CA-291-49 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

  1. OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE BIN, LOOKING NORTHEAST. REMAINS OF A BLACKSMITH'S FORGE AND WORK CAN BE SEEN JUST BELOW THE ORE BIN (SEE CA-291-32 FOR DETAIL). ROCK FOUNDATIONS LOCATED JUST ABOVE THE ORE BIN AND ALONG THE FIRST RIDGELINE ARE TENT PADS. SEE CA-291-24 FOR IDENTICAL B&W NEGATIVE. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

  2. 40 CFR 440.40 - Applicability; description of the mercury ore subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... mercury ore subcategory. 440.40 Section 440.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The provisions... produce mercury ores; and (b) mills beneficiating mercury ores by gravity separation methods or by...

  3. 40 CFR 440.40 - Applicability; description of the mercury ore subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... mercury ore subcategory. 440.40 Section 440.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The provisions... produce mercury ores; and (b) mills beneficiating mercury ores by gravity separation methods or by...

  4. 40 CFR 440.40 - Applicability; description of the mercury ore subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... mercury ore subcategory. 440.40 Section 440.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The provisions... produce mercury ores; and (b) mills beneficiating mercury ores by gravity separation methods or by...

  5. Sealing Out-Of-Round Tubes With O-Rings

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.

    1991-01-01

    Glass or ceramic tubes out-of-round sealed effectively by ordinary O-rings in caps of modified hydraulic fittings. In typical connection, O-ring squeezed between two surfaces having inward-opening slants of 5 degrees or 10 degrees. Slanted surfaces force ring inward, compressing it around tube. Connector metal fitting, tightened by hand around O-ring, seals O-ring against tube as much as 1/16 in. out of round. Modified connectors seal glass or ceramic tubes against gas or vacuum leakage in furnaces, vacuum systems, and tubes for glassblowing equipment.

  6. 34. VIEW OF VIVIANNA WORKS ORE SORTING AND CRUSHING PLATFORM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. VIEW OF VIVIANNA WORKS ORE SORTING AND CRUSHING PLATFORM LOOKING EAST, NORTHEAST. NOTICE RAIL TIES EMBEDDED IN CONCRETE. - Mariscal Quicksilver Mine & Reduction Works, Terlingua, Brewster County, TX

  7. 4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, c. 1912. SHOWS TIMBER FRAMING UNDER CONSTRUCTION FOR EAST AND WEST CRUDE ORE BINS AT PREVIOUS LOCATION OF CRUSHER HOUSE, AND SNOW SHED PRESENT OVER SOUTH CRUDE ORE BIN WITH PHASE CHANGE IN SNOW SHED CONSTRUCTION INDICATED AT EAST END OF EAST CRUDE ORE BIN. THIS PHOTOGRAPH IS THE FIRST IMAGE OF THE MACHINE SHOP, UPPER LEFT CORNER. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  8. Experimenting With Ore: Creating the Taconite Process; flow chart of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Experimenting With Ore: Creating the Taconite Process; flow chart of process - Mines Experiment Station, University of Minnesota, Twin Cities Campus, 56 East River Road, Minneapolis, Hennepin County, MN

  9. Characterization of energy critical elements in ore resources and associated waste tailings: Implications for recovery and remediation

    NASA Astrophysics Data System (ADS)

    McClenaghan, Sean H.

    2015-04-01

    The occurrence of Energy Critical Elements (ECE) in primary ore minerals and their subsequent enrichment in waste tailings is of great metallurgical interest. Recovery of many ECEs, in particular In, Ge, and Ga have come chiefly as a by-product of base-metal production (smelting and refining); these elements are found only at very low levels in the Earth's crust and do not typically form economic deposits on their own. As the ECEs become more important for a growing number of technological applications, it is critical to map the distribution of these elements in ore and waste (gangue) minerals to optimize their recovery and remediation. The characterization and beneficiation of ECEs is best illustrated for Zn-rich ore systems, where a mineral such as sphalerite (ZnS) will concentrate a number of major (Fe, Mn) and important trace elements (Cd, Se, In, Ge, Te, Sn, Bi, Sb, Hg). Interestingly, the mineral chemistry of sphalerite will often differ between different styles of mineralization (i.e., granite-hosted veins versus volcanic-hosted massive sulfides) and can even exhibit considerable variability within a deposit in response to metal zonation across hydrothermal facies. This has significant metallurgical implications for the blending of ore resources, the efficient production of Zn concentrates, and their ultimate value during the smelting and refining stages. Gangue minerals transferred to waste tailings may also exhibit significant enrichment in ECEs and precious metals; including Au in pyrite-arsenopyrite, and rare earth elements in a range of carbonate and phosphate minerals. In situ micro-analytical techniques are ideal for the quantitative measurement of trace elements in ore minerals as well as associated gangue materials. Recent advances in ICP-MS and ICP-OES technology coupled with newer classes of UV Excimer lasers (native 193 nm light) have allowed for more discrete analyses, permitting micro-chemical mapping at small scales (<10 microns). Further

  10. Sediment-hosted Pb-Zn Deposits: a global perspective

    USGS Publications Warehouse

    Leach, David L.; Sangster, Donald F.; Kelley, Karen D.; Large, R; Garven, G.; Allen, Craig R.

    2005-01-01

    Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and dominate world production of these metals. They are a chverse group of ore deposits hosted by a wide variety of carbonate and siliciclastic roch that have no obviolls genetic association with igneous activity. A nmge of ore-fortl1ing processes in a vmiety of geologic and tectonic environments created these deposits over at least two billion years of Earth history. The metals were precipitated by basinal brines in synsedimentary and early diagenetic to low-grade metamorphic environments. The deposits display a broad range of relationships to enclosing host rocks that includes stratiform, strata-bound, and discordant ores. These ores are divided into two broad subt)1Jes: Mississippi Valley-type (MVT) and sedimentmy exhalative (SEDEX), Despite the "exhalative" component inherent in the term "SEDEX," in this manusclipt, direct evidence of an exhalite in the ore or alteration component is not essential for a deposit to be classified as SEDEX. The presence of laminated sulfides parallel to bedding is assumed to be permissive evidence for exhalative ores. The chstinction between some SEDEX and MVT depOSits can be quite subjective because some SEDEX ores replaced carbonate, whereas some MVT depOSits formed in an early diagenetic environment and display laminated ore textures. Geologic and resource information are presented for 248 depositS that provide a framework to describe ,mel compare these deposits. Nine of tlle 10 largest sediment-hosted Pb-Zn deposits are SEDEX, Of the deposits that contain at least 2.5 million metric tons (Mt), there are 35 SEDEX (excluding Broken Hill-type) deposits and 15 MVT (excluding Iris-type) deposits. Despite the skewed distribution of the deposit size, the two deposits types have an excellent correlation between total tonnage and tonnage of contained metal (Pb + Zn), with a fairly consistent ratio of about lO/l, regardless of the size of the deposit or

  11. Bioprocessing of ores: Application to space resources

    NASA Technical Reports Server (NTRS)

    Johansson, Karl R.

    1992-01-01

    The role of microorganisms in the oxidation and leaching of various ores (especially those of copper, iron, and uranium) is well known. This role is increasingly being applied by the mining, metallurgy, and sewage industries in the bioconcentration of metal ions from natural receiving waters and from waste waters. It is concluded that bioprocessing using bacteria in closed reactors may be a variable option for the recovery of metals from the lunar regolith. Obviously, considerable research must be done to define the process, specify the appropriate bacteria, determine the necessary conditions and limitations, and evaluate the overall feasibility.

  12. Geochemical Modeling of Zinc Silicate Ore Formation from Sedimentary Hydrothermal Fluids

    NASA Astrophysics Data System (ADS)

    Appold, M. S.

    2008-12-01

    Sediment-hosted zinc deposits dominated by willemite (Zn2SiO4) instead of sphalerite (ZnS) are known from several prominent occurrences worldwide, including Vazante, Brazil, the Aroona Trend, Australia, Kabwe, Zambia, Berg Aukas, Namibia, and Abu Samar, Sudan. Although willemite-dominant zinc deposits appear to be much less common and are on average smaller than sphalerite-dominant zinc deposits, they nonetheless represent major enrichments of zinc in the Earth's crust, reaching sizes on the order of 1's to 10's of millions of tons and grades commonly between 20 and 40%. Sediment-hosted willemite- and sphalerite-dominant deposits share many similarities including their predominantly carbonate host rocks, gangue mineralogy, presumed derivation from sedimentary basinal brines, and spatial proximity. However, the conditions and processes that led to one style of mineralization versus the other have only recently begun to be investigated. The current study presents solubility, reaction path, and reactive transport modeling results that attempt to define more clearly the conditions that favor willemite ore formation in sedimentary basins, with a focus on the Vazante deposit. Solubility calculations for willemite and sphalerite as a function of temperature, pH, salinity, and oxidation potential were carried out using a simple 3 molal NaCl solution saturated with respect to quartz. The results show that (1) willemite solubility is relatively insensitive to changes in temperature and oxidation potential whereas sphalerite solubility decreases sharply with decreasing temperature and oxidation potential, (2) willemite solubility decreases more strongly than sphalerite with increasing pH, (3) willemite and sphalerite have a similar strong decrease in solubility with decreasing salinity. The results support a previously proposed genetic model for a willemite-dominant, sphalerite-subordinate ore body like Vazante in which a hot, acidic, metal-rich ore fluid mixed with a cooler

  13. Sm-Nd and Rb-Sr dating of an Archean massive sulfide deposit: Kidd Creek, Ontario

    SciTech Connect

    Maas, R.; McCulloch, M.T.; Campbell, I.H.; Coad, P.R.

    1986-07-01

    Highly altered felsic metavolcanics associated with the Kidd Creek, Ontario, Cu-Zn massive sulfide deposit show a large range of Sm/Nd ratios and yield a Sm-Nd isochron of 2674 +/- 40 Ma (initial ratio epsilon/sub Nd/ = 1.55 +/- 0.30), which represents the time of rare-earth-element redistribution during intense hydrothermal alteration. That the Sm-Nd age is consistent with age constraints on ore deposition provided by precise U-Pb zircon data indicates contemporaneity of ore deposition, hydrothermal alteration, and rare-earth mobility. The age is therefore interpreted as a minimum age of ore deposition. In contrast, the Rb-Sr age of the altered rocks, as well as the metavolcanic rocks outside the alteration zone, has been reset at 2576 +/- 26 Ma, most likely as a result of widespread low-temperature metasomatism unrelated to ore deposition. The results suggest that Sm-Nd dating could be a useful tool in the study of ore deposits and, potentially, in the study of a wide range of mineralizations. Initial epsilon/sub Nd/(T) values for massive ore, altered felsic volcanics, and their weakly altered precursors are identical, indicating derivation and redistribution of light-rare-earth elements within the altered footwall volcanics. These data suggest that the footwall volcanics have also supplied part of the base metals to the stratiform ore.

  14. Gold, base-metal, and related deposits of North Carolina

    USGS Publications Warehouse

    Luttrell, Gwendolyn Werth

    1978-01-01

    Gold, silver, copper, lead, zinc, pyrite, tin, cobalt, molybdenum, tungsten, barite, and rare-earths have been mined in North Carolina. Gold, with by-product silver, occurs in veins and mineralized shear zones in metamorphic rocks of the Piedmont province and in placers derived from these deposits. Copper occurs with complex sulfide ores in quartz veins in the metamorphic rocks of the Piedmont province and in massive pyrrhotite-pyrite deposits in crystalline rocks west of the Blue Ridge. Lead and zinc occur in complex ores of gold, copper, lead, zinc, and silver in veins and replacements in metamorphic rocks. Pyrite occurs in crystalline metamorphic rocks. Tin occurs in pegmatite and placer deposits in crystalline rocks near Kings Mountain. Cobalt minerals with ores of iron or gold have been reported in a few areas in the Piedmont. Molybdenum occurs along the borders of a granite body in Halifax County. Tungsten minerals occur with copper sulfide ores in Cabarrus and Vance Counties. Barite occurs in quartz veins and associated with sulfide minerals in Orange, Madison, Cleveland, and Gaston Counties. Ore-earths occur with sulfides in vein deposits in Cabarrus County.

  15. Geostatistical Approach to Estimating the Gold Ore Characteristics and Gold Reserves: A Case Study Daksa Area, Quang Nam Province, Viet Nam

    NASA Astrophysics Data System (ADS)

    Luan Truong, Xuan; Luong Le, Van; Quang Truong, Xuan

    2015-04-01

    Daksa gold deposit is the biggest gold deposits in Vietnam. The Daksa geological structure complicated, distributed mainly metamorphosed sedimentary NuiVu formation (PR3-?1nv2). The sulfide gold ore bodies distributed in quartz schist, quartz - biotite related to faut and distribution wing anticline. The gold ore bodies form circuits, network circuits, circuits lenses; fill the cup surface layer of the developing northeast - southwest; is the less than or west longitude north - SE. The results show that, Au and accompanying elements (Ag, Pb and Zn) have correlated pretty closely. All of its consistent with the logarithmic distribution standard, in accordance with the law of distribution of content mineral rare. The structure functions have nugget effect and spherical models with show that Au and accompanying elements special variation are changes. Au contents shown local anisotropy, no clearly anisotropy (K=1,17) and weakly anisotropy (K=1,4). Intensity mineralization of the ore bodies are quite high with demand spherical conversion coefficient ranging from 0.49 to 0.75 and from 0.66 to 0.97 (for other body). With nugget effects, ore bodies shown that it is consistent with mineralization in the ore bodies study, ore erasable, micro vein, infilling fractures in quartz vein. All of variogram presents local anisotropy, indicated gold mineralization at study area has least two-mineralization stages, consistent with the analysis of mineralography samples. By the results of the structure function study, the authors present the system optimization for exploration deposit and used to evaluate gold reserves by Ordinary Kriging. High accuracy of Kriging estimation results are expressed in the minimum Kriging variance, by compare the results calculated by some other methods (such as distance inverse weighting method, ..) and specially compare to the results of a some blocks have been exploited. Key words: Geostat and gold deposits VN. Daksa and gold mineralization. Geostat

  16. A new model for tabular-type uranium deposits

    USGS Publications Warehouse

    Sanford, R.F.

    1992-01-01

    Tabular-type uranium deposits occur as tabular, originally subhorizontal bodies entirely within reduced fluvial sandstones of Late Silurian age or younger. This paper proposes that belts of tabular-type uranium deposits formed in areas of mixed local and regional groundwater discharge shortly after deposition of the host sediments. The general characteristics of tabular-type uranium deposits indicate that their essential feature was the formation at a density-stratified ground-water interface in areas of local and regional ground-water discharge. Reconstruction of the paleohydrogeology is the key to understanding the formation of these deposits. Geologic ground-water controls that favor discharge, such as the pinch-out of major aquifers, are also favorable for uranium ore. The combination of topographic and geologic features that both cause discharge is most favorable for ore deposition. -from Author

  17. The Geohydrology of MVT-Ore Genesis in the Canning Basin, Western Australia

    NASA Astrophysics Data System (ADS)

    Garven, G.; Wallace, M. M.

    2009-05-01

    In the Lennard Shelf, Western Australia, epigenetic MVT-type Pb-Zn mineralization occurs in Middle Devonian evaporitic dolomites which were part of a barrier reef system (Hurley & Lohmann, 1989). Ore mineralization exhibits a strong structural control at the basin scale and normal faults probably controlled pathways for brine and petroleum migration that affected ore deposition (Wallace et al., 1999). For the Canning basin, finite element simulations show that compaction was the most important process for creating overpressures and driving basinal fluids in this thick extensional basin. Basinal fluids are shown to have been driven across the Fitzroy Trough through permeable and deeply buried Silurian-Ordovician aquifer units. The fluids then migrated upwards at rates of m/yr up during periods of episodic extension (Braun, 1992) where fluid flow was channeled by major normal fault zones like the Cadjebut and Pinnacles Faults. Reactive flow simulations test a petroleum-reservoir model for mineralization whereby metal-bearing brines mix with accumulated hydrocarbons (Anderson & Garven, 1987). The results show that compaction-driven flow, as proposed by Beales & Jackson (1966) and Jackson & Beales (1967), works rather well in this ore district--other mechanisms such as sealevel tidal pumping (Cathles, 1988) or topographic drive (Solomon & Groves, 1994) are more tenuous and really unnecessary from a mass transport or geohydrologic basis.

  18. Ore grade decrease as life cycle impact indicator for metal scarcity: the case of copper.

    PubMed

    Vieira, Marisa D M; Goedkoop, Mark J; Storm, Per; Huijbregts, Mark A J

    2012-12-01

    In the life cycle assessment (LCA) of products, the increasing scarcity of metal resources is currently addressed in a preliminary way. Here, we propose a new method on the basis of global ore grade information to assess the importance of the extraction of metal resources in the life cycle of products. It is shown how characterization factors, reflecting the decrease in ore grade due to an increase in metal extraction, can be derived from cumulative ore grade-tonnage relationships. CFs were derived for three different types of copper deposits (porphyry, sediment-hosted, and volcanogenic massive sulfide). We tested the influence of the CF model (marginal vs average), mathematical distribution (loglogistic vs loglinear), and reserve estimate (ultimate reserve vs reserve base). For the marginal CFs, the statistical distribution choice and the estimate of the copper reserves introduce a difference of a factor of 1.0-5.0 and a factor of 1.2-1.7, respectively. For the average CFs, the differences are larger for these two choices, i.e. respectively a factor of 5.7-43 and a factor of 2.1-3.8. Comparing the marginal CFs with the average CFs, the differences are higher (a factor 1.7-94). This paper demonstrates that cumulative grade-tonnage relationships for metal extraction can be used in LCA to assess the relative importance of metal extractions.

  19. Gold supported iron oxide-hydroxide derived from iron ore tailings for CO oxidation

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Das, B.; Satpati, B.; Mishra, B. K.

    2009-04-01

    Iron ore tailing, a waste material of iron ore industry, has been used to prepare iron oxide-hydroxide support for anchoring nano-gold particles. FeOOH was prepared from iron chloride solution obtained from acid digestion of iron ore tailing. Precipitation deposition method was used to prepare Au supported FeOOH. The samples were characterized by XRD, TEM, TG-DTA and FTIR. The XRD studies have confirmed the FeOOH phase and the TEM studies reveal the anchoring of gold particles on FeOOH whose size is about 5 nm. FTIR spectra showed the vibration mode of metal-oxygen bond and the presence of hydroxyl group in FeOOH and Au/FeOOH. TG-DTA results confirmed dehydration of FeOOH and the process is retarded by the presence of Au particles. The catalytic conversion of carbon monoxide by Au/FeOOH was around 55% but the catalyst became inactive after pretreatment at 300 °C in presence of oxygen which led to agglomeration of Au particles and removal of hydroxyl groups from the surface of FeOOH.

  20. Application of singular value decomposition (SVD) in extraction of gravity components indicating the deeply and shallowly buried granitic complex associated with tin polymetallic mineralization in the Gejiu tin ore field, Southwestern China

    NASA Astrophysics Data System (ADS)

    Chen, Yongqing; Zhang, Lina; Zhao, Binbin

    2015-12-01

    The Gejiu tin polymetallic ore deposit, located at the westernmost end of the Cathaysia Block, is one of the largest tin polymetallic ore deposits in the world. It is associated with a magmatic-hydrothermal ore-forming system triggered by the deeply buried geological structures and concealed granites. A singular value decomposition (SVD) program on a MATLAB platform was effectively used to extract deeply buried geological information reflecting deep-seated geological structures and the concealed granites by decomposing gravity signals within the Gejiu tin polymetallic ore field. Firstly, the gravity signals were decomposed into a few components with different eigenvalues using a singular value decomposition (SVD) approach. Secondly, the thresholds between the eigenvalues of gravity components reflecting deeply and shallowly buried ore-controlling geological structures and/or geological bodies were established by a multifractal method. Finally, the images of gravity components reflecting deeply and shallowly buried ore-controlling geological structures and/or geological bodies were reconstituted. This yielded two layers of significant two dimensional singular value gravity component images that indicate deeply and shallowly buried ore-controlling geological structures and/or geological bodies, respectively. The deep layer of gravity component image reveals a negative gravity anomaly (I) which indicates that the granites exposed in the west ore field, bounded by the Gejiu Fault, may be extended to the east ore field at depth, forming concealed granites (Fig. 4). The shallow layer of gravity component image reveals a structural framework created by two groups of NW-trending and three groups of NE-trending positive gravity component images defining two negative gravity anomalies (I and II), which may reflect existence of the exposed granites in the western ore field (I) and the concealed granites in the eastern ore field (II) (Figs. 5 and 6). Almost all tin

  1. Rare earth element metasomatism in hydrothermal systems: The Willsboro-Lewis wollastonite ores, New York, USA

    USGS Publications Warehouse

    Whitney, P.R.; Olmsted, J.F.

    1998-01-01

    granulite facies metamorphism homogenized zoned mineral grains without causing complete intergranular reequilibration and does not appear to have significantly affected the whole-rock REE distributions. These results demonstrate that extensive REE metasomatism can occur in hydrothermal systems at shallow to intermediate depths and that REE geochemistry may be useful in discerning the origin of skarns and skarn-related ore deposits.

  2. High-grade iron ore at Windarling, Yilgarn Craton: a product of syn-orogenic deformation, hypogene hydrothermal alteration and supergene modification in an Archean BIF-basalt lithostratigraphy

    NASA Astrophysics Data System (ADS)

    Angerer, Thomas; Hagemann, Steffen G.; Danyushevsky, Leonid

    2013-08-01

    Banded iron formation (BIF)-hosted iron ore deposits in the Windarling Range are located in the lower greenstone succession of the Marda-Diemals greenstone belt, Southern Cross domain, Yilgarn Craton and constitute a total hematite-martite-goethite ore resource of minimum 52 Mt at 60 wt.% Fe (0.07 P). Banded iron formation is interlayered with high-Mg basalts at Windarling and precipitated during episodes of volcanic quiescence. Trace element content and the rare earth element (REE) ratios Y/Ho (42 to 45), Sm/Yb (1.5), together with positive La and Gd anomalies in `least-altered' hematite-magnetite-metachert-BIF indicate the precipitation from Archean seawater that was fertilised by hydrothermal vent fluids with a basaltic HREE-Y signature. Hypogene iron ore in sub-greenschist facies metamorphosed BIF formed during three distinct stages: ore stage 1 was a syn- to post-metamorphic, syn-D1, Fe-Ca-Mg-Ni-Co-P-REE metasomatism that produced local Ni-REE-rich Fe-dolomite-magnetite alteration in BIF. Hydrothermal alteration was induced by hot fluid flow controlled by brittle-ductile reactivation of BIF-basalt margins and crosscutting D1 faults. The Ni-Co-rich content of dolomite and a shift in REE ratios in carbonate-altered BIF towards Archean mafic rock signature (Y/Ho to 31 to 40, Sm/Yb to 1 to 2 and Gd/Gd* to 1.2 to 1.4) suggest that high-Mg basalts in the Windarling Range were the primary source of introduced metals. During ore stage 2, a syn-deformational and likely acidic and oxidised fluid flow along BIF-basalt margins and within D1 faults leached carbonate and precipitated lepidoblastic and anhedral/granoblastic hematite. High-grade magnetite-hematite ore is formed during this stage. Ore stage 3 hydrothermal specular hematite (spcH)-Fe-dolomite-quartz alteration was controlled by a late-orogenic, brittle, compressional/transpressional stage (D4; the regional-scale shear-zone-related D3 is not preserved in Windarling). This minor event remobilised iron oxides

  3. Genetic Pd, Pt, Au, Ag, and Rh mineralogy in Noril'sk sulfide ores

    NASA Astrophysics Data System (ADS)

    Spiridonov, E. M.; Kulagov, E. A.; Serova, A. A.; Kulikova, I. M.; Korotaeva, N. N.; Sereda, E. V.; Tushentsova, I. N.; Belyakov, S. N.; Zhukov, N. N.

    2015-09-01

    The undeformed ore-bearing intrusions of the Noril'sk ore field (NOF) cut through volcanic rocks of the Late Permian-Early Triassic trap association folded in brachysynclines. Due to the nonuniform load on the roof of intrusive bodies, most sulfide melts were squeezed, up to the tops of ore-bearing intrusions; readily fusible Ni-Fe-Cu sulfide melts were almost completely squeezed. In our opinion, not only one but two stages of mineralization developed at the Noril'sk deposits: (i) syntrap magmatic and (ii) epigenetic post-trap metamorphic-hydrothermal. All platinum-group minerals (PGM) and minerals of gold are metasomatic in the Noril'sk ores. They replaced sulfide solid solutions and exsolution structures. All types of PGM and Au minerals occur in the ores, varying in composition from pyrrhotite to chalcopyrite, talnakhite, mooihoekite, and rich in galena; they are localized in the inner and outer contact zones and differ only in the quantitative proportions of ore minerals. The aureoles of PGM and Au-Ag minerals are wider than the contours of sulfide bodies and coincide with halos of fluid impact on orebodies and adjacent host rocks. The pneumatolytic PGM and Au-Ag minerals are correlated in abundance with the dimensions of sulfide bodies. Their amounts are maximal in veins of late fusible ore composed of eutectic PbS ss and iss intergrowths, as well as at their contacts. The Pd and Pt contents in eutectic sulfide ores of NOF are the world's highest. In the process of noble-metal mineral formation, the fluids supply Pd, Pt, Au, As, Sb, Sn, Bi, and a part of Te, whereas Fe, Ni, Cu, Pb, Ag, Rh, a part of Te and Pd are leached from the replaced sulfide minerals. The pneumatolytic PGM of the early stage comprises Pd and Pt intermetallic compounds enriched in Au along with Pd-Pt-Fe-Ni-Cu-Sn-Pb(As) and (Pd,Pt,Au)(Sn,Sb,Bi,Te,As) solid solutions. Pneumatolytic PGM and Au minerals of the middle stage are products of solid-phase transformation and recrystallization of

  4. Ore-bearing hydrothermal metasomatic processes in the Elbrus volcanic center, the northern Caucasus, Russia

    NASA Astrophysics Data System (ADS)

    Gurbanov, A. G.; Bogatikov, O. A.; Dokuchaev, A. Ya.; Gazeev, V. M.; Abramov, S. S.; Groznova, E. O.; Shevchenko, A. V.

    2008-06-01

    -ralstonite, and fluorite-identified in these metasomatic rocks for the first time. By analogy with porphyry Cu-Mo deposits in Chile and the United States, the ore mineralization of the KOMS may be classified by composition and textural and structural attributes as a supraore level of porphyry copper genetic type. The volcanic rocks of the KOMS and the EVC as a whole are enriched in Ag, Mo, Zn, As, Sb, Se, and Ba. Judging from the scale of argillic alteration and taking into account the data on porphyry Cu-Mo ore-magmatic systems of the Greater Caucasus, veined Pb-Zn ore mineralization may be expected in the propylitic zone at a depth down to 1000 m from the present-day erosion level of the KOMS. Stringer-disseminated Au-Ag, Cu, and Cu-Mo ore mineralization of the upper part of the porphyry ore-magmatic system related to subvolcanic dacitic intrusions may be localized somewhat deeper.

  5. The timing of ore formation in southeast Missouri: Rb-Sr glauconite dating at the Magmont mine, Viburnum trend.

    USGS Publications Warehouse

    Stein, H.J.; Kish, S.A.

    1985-01-01

    Seven glauconite samples from the Magmont area yield a 359 + or - 22 m.y. Rb-Sr isochron. The Rb/Sr ratios for these seven samples are significantly lower than the ratios for glauconite samples from distant, unmineralized sites. The glauconites from Magmont are postulated to have been affected by the same thermochemical event(s) that produced the SE Missouri ore deposits, and therefore to date that mineralization.-G.J.N.

  6. Geochronology and isotopic-geochemical characteristics of magmatic complexes of gold-silver ore-magmatic structures in the Chukotka sector of the Russian Arctic coast

    NASA Astrophysics Data System (ADS)

    Sakhno, V. G.; Grigoriev, N. V.; Kurashko, V. V.

    2016-05-01

    The first results of SHRIMP dating of magmatic complexes and associated gold-silver deposits and ore occurrences (Kupol, Dvoinoe, Moroshka, and others) in the Chukotka sector of the Russian Arctic coast are discussed. The petrological and isotopic-geochronological data are used for reconstructing their formation conditions.

  7. 27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW SKIP TIES UP AT DOCK. THE UNLOADERS OPERATE ALMOST CONTINUOUSLY DURING THE SHIPPING SEASON, WHICH USUALLY RUNS FROM APRIL UNTIL LATE DECEMBER OR EARLY JANUARY. VIEW HERE IS LOOKING NORTHEAST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  8. TRAM HOUSE INTERIOR, LOOKING SOUTHEAST. NOTE DEPARTING ORE BUCKET "12" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    TRAM HOUSE INTERIOR, LOOKING SOUTHEAST. NOTE DEPARTING ORE BUCKET "12" AND SUSPENSION CABLE ANGLING DOWN THROUGH FLOOR AT LOWER LEFT. LARGE LEVER ON SIDE OF BUCKET ALLOWS IT TO BE ROTATED FOR DUMPING ORE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  9. 24. REAR ELEVATION, HULETT ORE UNLOADERS. TRACKS CARRYING THE FRONT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. REAR ELEVATION, HULETT ORE UNLOADERS. TRACKS CARRYING THE FRONT END AND REAR LEGS OF THE HULETT UNLOADERS ARE LAID ON THE DOCK AND REAR WALLS, RESPECTIVELY; BOTH WALLS ARE MADE OF REINFORCED CONCRETE SUPPORTED ON CONCRETE PILES. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  10. Upgrading Titanium Ore Through Selective Chlorination Using Calcium Chloride

    NASA Astrophysics Data System (ADS)

    Kang, Jungshin; Okabe, Toru H.

    2013-06-01

    To develop a simple and effective process for upgrading low-grade titanium ore (ilmenite, mainly FeTiO3), a new selective chlorination process based on the use of calcium chloride (CaCl2) as the chlorine source was investigated in this study. Titanium ore and a titanium ore/CaCl2 mixture were placed in two separate crucibles inside a gas-tight quartz tube that was then positioned in a horizontal furnace. In the experiments, the titanium ore in the two crucibles reacted with either HCl produced from CaCl2 or CaCl2 itself at 1100 K (827 °C), leading to the selective removal of the iron present in the titanium ore as iron ch