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Sample records for lode gold deposit

  1. Source and location mechanism for lode gold deposits hosted in metamorphic rocks in northeastern Hunan, China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    For understanding the source and location mechanism of lode gold deposits hosted in metamorphic rocks in northeastern Hunan, the authors analyzed the REE (rare earth elements) in ores and their host rocks, metallogenic elements in host rocks near and distant from the ore-bodies, and characteristics of ore-controlling structures, and deduced their genetic implication. Their geochemical features of REE and metallogenic elements suggest that they are formed by mobilization of dispersed metallogenic materials in Lengjiaxi Group of Middle Proterozoic during deformation and metamorphism process, mainly in Wulingian period. From the attributes of ore-controlling structures and regularity of location of gold metallization, it is concluded that the location of gold deposits is closely related to reverse shearing. Ore-forming fluids are focused on the secondary faults and extension fractures of reverse shear zones of nearly EW strike by stress-driven diffusion and seismic pumping.

  2. Controls on lode gold mineralization, Romite deposit, South Eastern Desert, Egypt

    Directory of Open Access Journals (Sweden)

    Basem A. Zoheir

    2012-09-01

    The carbonate δ13CPDB and δ18OSMOW isotope signatures preclude an organic source of the ore fluid, but metamorphic and magmatic sources are still valid candidates. The intense deformation and lack of magmatism in the deposit area argue for metamorphic dewatering of greenstone rocks as the most likely fluid source. The narrow ranges of δ13C (−4.6‰ to −3.1‰ and δ18O (11.9‰–13.7‰ in carbonate minerals in lodes imply a corresponding uniformity to the ambient temperature and δ13CCO2 (δ13CΣC of the ore fluids. The calculated δ18OH2O values of 6.9‰–7.9‰ for ore fluids, based on δ18O values of vein quartz further suggest a likely metamorphic origin.

  3. Sources of ore-forming fluids and metallic materials in the Jinwozi lode gold deposit, eastern Tianshan Mountains of China

    Institute of Scientific and Technical Information of China (English)

    LIU; Wei(刘伟); LI; Xinjun(李新俊); DENG; Jun(邓军)

    2003-01-01

    This paper presents gas compositions and H-, O-isotope compositions of sulfide- and quartz-hosted fluid inclusions, and S-, Pb-isotope compositions of sulfide separates collected from the principal Stage 2 ores in Veins 3 and 210 of the Jinwozi lode gold deposit, eastern Tianshan Mountains of China. Fluid inclusions trapped in quartz and sphalerite are dominantly primary. H- and O-isotopic compositions of pyrite-hosted fluid inclusions indicate two major contributions to the ore-forming fluid that include the degassed magma and the meteoric-derived but rock 18O-buffered groundwater. However, H- and O-isotopic compositions of quartz-hosted fluid inclusions essentially suggest the presence of groundwater. Sulfide-hosted fluid inclusions show considerably higher abundances of gaseous species CO2, N2, H2S, etc. Than quartz-hosted ones. The linear trends among inclusion gaseous species reflect the mixing tendency between the gas-rich magmatic fluid and the groundwater. The relative enrichment of gaseous species in sulfide-hosted fluid inclusions, coupled with the banded ore structure indicating alternate precipitation of quartz with sulfide minerals, suggests that the magmatic fluid has been inputted to the ore-forming fluid in pulsation. Sulfur and lead isotope compositions of pyrite and galena separates indicate an essential magma derivation for sulfur but the multiple sources for metallic materials from the mantle to the bulk crust.

  4. Magmatic-hydrothermal origin of the early Triassic Laodou lode gold deposit in the Xiahe-Hezuo district, West Qinling orogen, China: implications for gold metallogeny

    Science.gov (United States)

    Jin, Xiao-ye; Li, Jian-wei; Hofstra, Albert H.; Sui, Ji-xiang

    2017-08-01

    The Xiahe-Hezuo district in the West Qinling orogen contains numerous Au-(As-Sb) and Cu-Au-(W) deposits. The district is divided into eastern and western zones by the Xiahe-Hezuo Fault. The western zone is exposed at a shallow level and contains sediment-hosted disseminated Au-(As-Sb) deposits, whereas the eastern zone is exposed at a deeper level and contains Cu-Au-(W) skarn and lode gold deposits within or close to granitic intrusions. The Laodou gold deposit in the eastern zone consists of auriferous quartz-sulfide-tourmaline and minor quartz-stibnite veins that are structurally controlled by fault zones transecting the Laodou quartz diorite porphyry stock and enveloped by potassic and phyllic alteration. Both the veins and alteration halos commonly contain quartz, sericite, tourmaline, pyrite, and arsenopyrite, with minor galena, sphalerite, chalcopyrite, tetrahedrite, and enargite. Gold occurs mainly as invisible gold in pyrite or arsenopyrite and locally as inclusions less than 50 μm in diameter. The zircon U-Pb age of 247.6 ± 1.3 Ma (2 σ) on the host quartz diorite porphyry and the sericite 40Ar/39Ar plateau ages of 249.1 ± 1.6 and 249.0 ± 1.5 Ma (2 σ) on two ore-related hydrothermal sericite samples are within analytical errors of one another. At the formation temperature (275 °C) inferred from microthermometric measurements of fluid inclusion, sericite and tourmaline yield calculated δDH2O values of -70 to -45‰ and δ 18OH2O of 5.8 to 9.7‰, while quartz yields calculated δ 18OH2O values of 5.1˜5.7‰. Hydrothermal tourmaline in quartz-sulfide-tourmaline veins has δ 11B of -11.2 to -0.9‰ (mean of -6.3‰) that are similar to the values of magmatic tourmaline (-8.9 to -5.5‰ with a mean of -6.8‰) in the host quartz diorite porphyry. The δ 34S values of sulfide minerals range from -5.9 to +5.8‰ with a mean of -0.6‰ that is typical of magmatic sulfur. Pyrite from hydrothermally altered quartz diorite porphyry and quartz

  5. Magmatic-hydrothermal origin of the early Triassic Laodou lode gold deposit in the Xiahe-Hezuo district, West Qinling orogen, China: implications for gold metallogeny

    Science.gov (United States)

    Jin, Xiao-ye; Li, Jian-wei; Hofstra, Albert H.; Sui, Ji-xiang

    2016-12-01

    The Xiahe-Hezuo district in the West Qinling orogen contains numerous Au-(As-Sb) and Cu-Au-(W) deposits. The district is divided into eastern and western zones by the Xiahe-Hezuo Fault. The western zone is exposed at a shallow level and contains sediment-hosted disseminated Au-(As-Sb) deposits, whereas the eastern zone is exposed at a deeper level and contains Cu-Au-(W) skarn and lode gold deposits within or close to granitic intrusions. The Laodou gold deposit in the eastern zone consists of auriferous quartz-sulfide-tourmaline and minor quartz-stibnite veins that are structurally controlled by fault zones transecting the Laodou quartz diorite porphyry stock and enveloped by potassic and phyllic alteration. Both the veins and alteration halos commonly contain quartz, sericite, tourmaline, pyrite, and arsenopyrite, with minor galena, sphalerite, chalcopyrite, tetrahedrite, and enargite. Gold occurs mainly as invisible gold in pyrite or arsenopyrite and locally as inclusions less than 50 μm in diameter. The zircon U-Pb age of 247.6 ± 1.3 Ma (2σ) on the host quartz diorite porphyry and the sericite 40Ar/39Ar plateau ages of 249.1 ± 1.6 and 249.0 ± 1.5 Ma (2σ) on two ore-related hydrothermal sericite samples are within analytical errors of one another. At the formation temperature (275 °C) inferred from microthermometric measurements of fluid inclusion, sericite and tourmaline yield calculated δDH2O values of -70 to -45‰ and δ 18OH2O of 5.8 to 9.7‰, while quartz yields calculated δ 18OH2O values of 5.1˜5.7‰. Hydrothermal tourmaline in quartz-sulfide-tourmaline veins has δ 11B of -11.2 to -0.9‰ (mean of -6.3‰) that are similar to the values of magmatic tourmaline (-8.9 to -5.5‰ with a mean of -6.8‰) in the host quartz diorite porphyry. The δ 34S values of sulfide minerals range from -5.9 to +5.8‰ with a mean of -0.6‰ that is typical of magmatic sulfur. Pyrite from hydrothermally altered quartz diorite porphyry and quartz

  6. Geology and origin of epigenetic lode gold deposits, Tintina Gold Province, Alaska and Yukon: Chapter A in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    Science.gov (United States)

    Goldfarb, Richard J.; Marsh, Erin E.; Hart, Craig J.R.; Mair, John L.; Miller, Marti L.; Johnson, Craig; Gough, Larry P.; Day, Warren C.

    2007-01-01

    More than 50 million ounces of lode gold resources have been defined in the previous 15 years throughout accreted terranes of interior Alaska and in adjacent continental margin rocks of Yukon. The major deposits in this so-called Tintina Gold Province formed around 105 to 90 million years ago in east-central Alaska and Yukon, and around 70 million years ago in southwestern Alaska, late in the deformational history of their host rocks. All gold deposits studied to date formed from CO2

  7. Lode-gold mineralization in the Tanami region, northern Australia

    Science.gov (United States)

    Huston, David L.; Vandenberg, Leon; Wygralak, Andrew S.; Mernagh, Terrence P.; Bagas, Leon; Crispe, Andrew; Lambeck, Alexis; Cross, Andrew; Fraser, Geoff; Williams, Nick; Worden, Kurt; Meixner, Tony; Goleby, Bruce; Jones, Leonie; Lyons, Pat; Maidment, David

    2007-01-01

    at an angle consistent with tensional fractures opened during E-W- to ENE-WSW-directed transpression. Many of these deposits are hosted by reactive rock units such as carbonaceous siltstone and iron formation. Ore deposition occurred at depths ranging from 1.5 to 11 km from generally low to moderate salinity carbonic fluids with temperatures from 200 to 430°C, similar to lode-gold fluids elsewhere in the world. These fluids are interpreted as the product of metamorphic dewatering caused by enhanced heat flow, although it is also possible that the fluids were derived from coeval granites. Lead isotope data suggest that lead in the ore fluids had multiple sources. Hydrogen and oxygen isotope data are consistent with both metamorphic and magmatic origins for ore fluids. Gold deposition is interpreted to be caused by fluid unmixing and sulfidation of host rocks. Fluid unmixing is caused by three different processes: (1) CO2 unmixing caused by interaction of ore fluids with carbonaceous siltstone; (2) depressurization caused by pressure cycling in shear zones; and (3) boiling as ore fluids move to shallow levels. Deposits in the Tanami region may illustrate the continuum model of lode-gold deposition suggested by Groves (Mineralium Deposita 28:366-374, 1993) for Archean districts.

  8. Epithermal mercury-antimony and gold-bearing vein lodes of southwestern Alaska

    Science.gov (United States)

    Gray, John E.; Gent, Carol A.; Snee, Lawrence W.; Wilson, Frederic H.; Goldfarb, Richard J.; Miller, Lance D.

    1997-01-01

    Epithermal mineral deposits and occurrences of southwestern Alaska consist of Hg-Sb and gold- and sulfide-bearing vein lodes. Numerous Hg-Sb lodes are located throughout a region measuring several tens of thousands of square kilometers in and surrounding the Kuskokwim River basin in southwestern Alaska. The Hg-Sb lodes are hosted in sedimentary rocks of the Cretaceous Kuskokwim Group, the Triassic to Cretaceous Gemuk Group, and the Paleozoic Holitna Group, as well as in Late Cretaceous and early Tertiary mafic to felsic intrusive rocks. Mineralized Hg-Sb vein and vein breccia lodes are found in the sedimentary or igneous rocks or at their contacts. The minerology of the Hg-Sb lodes is dominated by cinnabar and stibnite, with subordinate realgar, orpiment, and native mercury, pyrite, gold, and hematite, as well as solid and liquid hydrocarbons; quartz, carbonate, limonite, dickite, and sercite are alteration gangue minerals. The largest mercury mine in Alaska, Red Devil, produced about 36,000 flasks of mercury, but the Hg-Sb lodes of southwestern Alaska generally consist of small, discontinuous veins that rarely exceed a few meters in width and a few tens of meters in strike length. The Hg-Sb lodes generally contain about 1 to 5 percent Hg and less than 1 percent Sb and As but are generally poor in base emtals and precious metals. Anomalous concentrations of gold in some lodes, however, suggest that gold deposits may be present in higher temperature environments below some of the Hg-Sb lodes.The formation of the Hg-Sb lodes is closely correlated with igneous activity of a Late Cretaceous and early tertiary magmatic arc in southwestern Alaska. Geologic and geochemical characteristics of the Hg-Sb lodes suggest that ore fluids were generated in local sedimentary rocks as they were intruded by magmas. These intrusions provided the heat to initiate dehydration reactions and expel fluids from hydrous minerals and formational waters in the sedimentary rocks, causing

  9. Age constraints on Tarkwaian palaeoplacer and lode-gold formation in the Tarkwa-Damang district, SW Ghana

    Science.gov (United States)

    Pigois, J.-P.; Groves, D.I.; Fletcher, I.R.; McNaughton, N.J.; Snee, L.W.

    2003-01-01

    Two major epigenetic gold-forming events are recorded in the world-class gold province of southwest Ghana. A pre-Tarkwaian event was the source of the world-class Tarkwa palaeoplacers whereas post-Birimian and Tarkwaian deformation, which was related to the Eburnean orogeny, gave rise to the world-class (e.g. Prestea) to giant (e.g. Obuasi) orogenic gold deposits which have made the region famous for more than 2,500 years. A maximum age of 2133 ?? 4 Ma for Tarkwaian sedimentation is provided by 71 of 111 concordant SHRIMP II U Pb dates from detrital zircons in Tarkwaian clastic rocks from Damang and Bippo Bin, northeast of Tarkwa. The overall data distribution broadly overlaps the relatively poorly constrained ages of Birimian volcanism and associated Dixcove-type granitoid emplacement, indicating syntectonic development of the Tarkwaian sedimentary basin. These zircon ages argue against derivation of the palaeoplacer gold from an orogenic gold source related to the compressional phase of an orogeny significantly older than the Eburnean orogeny. Instead, they suggest that the gold source was either orogenic gold lodes related to an earlier compressional phase of a diachronous Eburnean orogeny or ca. 2200-2100 Ma intrusion-related gold lode. The CO2-rich fluid inclusions in associated vein-quartz pebbles are permissive of either source. At the Damang deposit, an epigenetic, orogenic lode-gold system clearly overprinted, and sulphidised low-grade palaeoplacer hematite magnetite gold occurrences in the Banket Series conglomerate within the Tarkwaian sedimentary sequence. Gold mineralisation is demonstrably post-peak metamorphism, as gold-related alteration assemblages overprint metamorphic assemblages in host rocks. In alteration zones surrounding the dominant, subhorizontal auriferous quartz veins, there are rare occurrences of hydrothermal xenotime which give a SHRIMP U Pb age of 2063 ?? 9 Ma for gold mineralisation. The similar structural timing of epigenetic gold

  10. Lores, legends and lodes from lake superior - Mother of copper deposits

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.

    "), operated by the Quincy Mining Company from 1865 to 1945, was the first of the lower-grade, altered amygdaloidal basalt deposits. The Cu- bearing conglomerates, discovered in 1859, led to the opening of mines on the Calumet lode in 1864. The conglomerates... tonnes. JOUR.GEOL.SOC.INDIA, VOL.60, NOV. 2002 In 1864, the Calumet Conglomerate Lode was found by E.D. Hulbert. After some years, the Hecla Mining Company operated this mine (C&H). In 1867, Quincy the president of C&H, appointed his brother...

  11. Deformation and metamorphism of gold-sulphide lodes in the Bhukia–Jagpura gold prospect, Rajasthan: Implications for ore genesis

    Indian Academy of Sciences (India)

    S Deol; A Chattopadhyay; M Deb

    2014-02-01

    The role of polyphase deformation in controlling the emplacement of gold-quartz lodes in dilational regimes is demonstrated from the Proterozoic Bhukia–Jagpura gold prospect in south Rajasthan. Earlier researchers deciphered the gold-sulphide mineralisation event as synchronous to the second phase of deformation (D2) without convincing microstructural or metamorphic evidences. In this contribution, we correlate the deformation and metamorphic imprints in the host rocks with those in the gold-sulphide mineralised zone, and present a new interpretation for the relative timing of gold emplacement vis-á-vis deformation. The ore-forming process first involved layer-parallel influx of ore-bearing hydrothermal fluids along S1 schistosity in the host rocks, synkinematic with respect to the first phase of deformation (D1). This initial ore concentration experienced metamorphism isofacially (∼500° C at 5.3 kb) along with its host rocks during D1, and subsequently underwent extensive remobilisation, giving rise to gold-bearing silicified lodes along the hinges and axial surfaces of F2 folds during D2.

  12. Detrital zircon without detritus: a result of 496-Ma-old fluid-rock interaction during the gold-lode formation of Passagem, Minas Gerais, Brazil

    Science.gov (United States)

    Cabral, Alexandre Raphael; Zeh, Armin

    2015-01-01

    Zircon and xenotime occur in tourmaline-rich hydrothermal pockets in the auriferous lode of Passagem de Mariana, a world-class gold deposit. Zircon grains show pristine oscillatory zoning, but many of them are altered, exhibiting porous domains filled with graphite. Uranium-Pb dating of zircon, using in-situ laser ablation-inductively coupled plasma-mass spectrometry, yields ages between 3.2 and 2.65 Ga, which match those for detrital zircon of the footwall quartzite of the > 2.65-Ga-old Moeda Formation. Discordant analyses point to zircon-age resetting during the Brasiliano orogeny at ca. 500 Ma. This interpretation is supported by U-Pb dating of euhedral xenotime immediately adjacent to altered zircon within the same tourmaline pocket. The xenotime grains give a Concordia age of 496.3 ± 2.0 Ma, which is identical to that determined for monazite of a quartz-hematite vein-type deposit (i.e., jacutinga lode) in the region (Itabira), another important mineralisation style of gold. The occurrence of relatively abundant inherited detrital zircon, but absence of rock fragments in the tourmaline pocket investigated here, implies that detrital material was completely replaced by tourmaline. The graphite overprint on the altered detrital zircon attests to a reducing fluid, which was likely formed by fluid-rock interaction with carbonaceous phyllite of the Batatal Formation, the host rock of the Passagem lode.

  13. Legacy of the California Gold Rush: Environmental geochemistry of arsenic in the southern Mother Lode Gold District

    Science.gov (United States)

    Savage, K.S.; Bird, D.K.; Ashley, R.P.

    2000-01-01

    Gold mining activity in the Sierra Nevada foothills, both recently and during the California Gold Rush, has exposed arsenic-rich pyritic rocks to weathering and erosion. This study describes arsenic concentration and speciation in three hydrogeologic settings in the southern Mother Lode Gold District: mineralized outcrops and mine waste rock (overburden); mill tailings submerged in a water reservoir; and lake waters in this monomictic reservoir and in a monomictic lake developing within a recent open-pit mine. These environments are characterized by distinct modes of rock-water interaction that influence the local transport and fate of arsenic. Arsenic in outcrops and waste rock occurs in arsenian pyrite containing an average of 2 wt% arsenic. Arsenic is concentrated up to 1300 ppm in fine-grained, friable iron-rich weathering products of the arsenian pyrite (goethite, jarosite, copiapite), which develop as efflorescences and crusts on weathering outcrops. Arsenic is sorbed as a bidentate complex on goethite, and substitutes for sulfate in jarosite. Submerged mill tailings obtained by gravity core at Don Pedro Reservoir contain arsenic up to 300 ppm in coarse sand layers. Overlying surface muds have less arsenic in the solid fraction but higher concentrations in porewaters (up to 500 ??g/L) than the sands. Fine quartz tailings also contain up to 3.5 ppm mercury related to the ore processing. The pH values in sediment porewaters range from 3.7 in buried gypsum-bearing sands and tailings to 7 in the overlying lake sediments. Reservoir waters immediately above the cores contain up to 3.5 ??g/L arsenic; lake waters away from the submerged tailings typically contain less than 1 ??g/L arsenic. Dewatering during excavation of the Harvard open-pit mine produced a hydrologic cone of depression that has been recovering toward the pre-mining groundwater configuration since mining ended in 1994. Aqueous arsenic concentrations in the 80 m deep pit lake are up to 1000 ??g

  14. Characteristics of gold deposits in northern Sonora, Mexico: a preliminary report

    Science.gov (United States)

    Silberman, M.L.; Giles, D.A.; Graubard, C.

    1988-01-01

    The complex geology of northern Sonora has a variety of environments suitable for gold mineralisation, and many of the gold prospects occur within or adjacent to the southwestern boundary of the megashear in Precambrian, Mesozoic and Tertiary rocks. The characteristics types of gold deposits have been delineated by reconnaissance field investigations of the authors. There are four main environments of lode gold deposits present in Sonora: epithermal veins and breccias; discontinuous quartz veins; structurally controlled Au; and carbonate sedimentary-hosted disseminated Au. -after Authors

  15. The giant Jiaodong gold province: The key to a unified model for orogenic gold deposits?

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2016-05-01

    Full Text Available Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially – associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve metamorphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedimentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many

  16. The giant Jiaodong gold province:The key to a unified model for orogenic gold deposits?

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; M. Santosh

    2016-01-01

    Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially e associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve meta-morphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedi-mentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many other subduction

  17. Geophysical modeling in gold deposit through DC Resistivity and Induced Polarization methods

    Directory of Open Access Journals (Sweden)

    César Augusto Moreira

    Full Text Available Abstract Ore mining fundamentally depends on the definition of its tenor and volume, something extremely complex in disseminated mineralization, as in the case of certain types of deposits of gold and sulfites. This article proposes the use of electrical tomography for definition of a geophysical signature in terms of electrical resistivity and chargeability, in an outcrop of mineralized quartz lode at the end of an inactive gold mine. One of the targets was to analyze the continuity of the mineralized body, the occurrence of new outcrops and the applicability of the method as an auxiliary tool in mineral extraction. Three parallel lines of electrical tomography in a dipole-dipole arrangement, being orthogonal to the orientation of the gold lode, were installed in an area outside the mine. The results allowed the geophysical characterization of the mineralized zone by high resistivity (above 1000Ω.m and high chargeability (above 30mV/V. The results of the 2D inversion models were interpolated in 3D visualization models, which allowed definition of the contour surfaces for the physical parameters measured, and the morphological pattern modeling of the mineralization. The data reveal the existence of a new lode in subsurface, localized 30m to the south of the lode outcrop. The versatility of the acquisition and data processing indicate the application potential of electrical tomography as a criterion for sampling and tenor definition in ore extraction activities, since it is objective and low cost.

  18. Geology of the Alaska-Juneau lode system, Alaska

    Science.gov (United States)

    Twenhofel, William Stephens

    1952-01-01

    The Alaska-Juneau lode system for many years was one of the worlds leading gold-producing areas. Total production from the years 1893 to 1946 has amounted to about 94 million dollars, with principal values in contained gold but with some silver and lead values. The principal mine is the Alaska-Juneau mine, from which the lode system takes its name. The lode system is a part of a larger gold-bearing belt, generally referred to as the Juneau gold belt, along the western border of the Coast Range batholith. The rocks of the Alaska-Juneau lode system consist of a monoclinal sequence of steeply northeasterly dipping volcanic, state, and schist rocks, all of which have been metamorphosed by dynamic and thermal processes attendant with the intrusion of the Coast Range batholith. The rocks form a series of belts that trend northwest parallel to the Coast Range. In addition to the Coast Range batholith lying a mile to the east of the lode system, there are numerous smaller intrusives, all of which are sill-like in form and are thus conformable to the regional structure. The bedded rocks are Mesozoic in age; the Coast Range batholith is Upper Jurassic and Lower Cretaceous in age. Some of the smaller intrusives pre-date the batholith, others post-date it. All of the rocks are cut by steeply dipping faults. The Alaska-Juneau lode system is confined exclusively to the footwall portion of the Perseverance slate band. The slate band is composed of black slate and black phyllite with lesser amounts of thin-bedded quartzite. Intrusive into the slate band are many sill-like bodies of rocks generally referred to as meta-gabbro. The gold deposits of the lode system are found both within the slate rocks and the meta-gabbro rocks, and particularly in those places where meta-gabbro bodies interfinger with slate. Thus the ore bodies are found in and near the terminations of meta-gabbro bodies. The ore bodies are quartz stringer-lodes composed of a great number of quartz veins from 6

  19. Effects of mother lode-type gold mineralization on 187Os/188Os and platinum group element concentrations in peridotite: Alleghany District, California

    Science.gov (United States)

    Walker, R.J.; Böhlke, J.K.; McDonough, W.F.; Li, J.

    2007-01-01

    Osmium isotope compositions and concentrations of Re, platinum group elements (PGE), and Au were determined for host peridotites (serpentinites and barzburgites) and hydrothermally altered ultramafic wall rocks associated with Mother Lode-type hydrothermal gold-quartz vein mineralization in the Alleghany district, California. The host peridotites have Os isotope compositions and Re, PGE, and Au abundances typical of the upper mantle at their presumed formation age during the late Proterozoic or early Paleozoic. The hydrothermally altered rocks have highly variable initial Os isotope compositions with ??os, values (% deviation of 187OS/188OS from the chondritic average calculated for the approx. 120 Ma time of mineralization) ranging from -1.4 to -8.3. The lowest Os isotope compositions are consistent with Re depletion of a chondritic source (e.g., the upper mantle) at ca. 1.6 Ga. Most of the altered samples are enriched in Au and have depleted and fractionated abundances of Re and PGE relative to their precursor peridotites. Geoehemical characteristics of the altered samples suggest that Re and some PGE were variably removed from the ultramafic rocks during the mineralization event. In addition to Re, the Pt and Pd abundances of the most intensely altered rocks appear to have been most affected by mineralization. The 187Os-depleted isotopic compositions of some altered rocks are interpreted to be a result of preferential 187Os loss via destruction of Re-rich phases during the event. For these rocks, Os evidently is not a useful tracer of the mineralizing fluids. The results do, however, provide evidence for differential mobility of these elements, and mobility of 187Os relative to the initial bulk Os isotope composition during hydrothermal metasomatic alteration of ultramafic rocks. ?? 2007 Society of Economic Geologists, Inc.

  20. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods

  1. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods Dece

  2. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods Dece

  3. Iron isotope constraints on the mineralization processes of the Sandaowanzi telluride gold deposit, NE China

    Science.gov (United States)

    Li, Xingxing; Liu, Junlai; Lu, Di; Ren, Shunli; Liu, Zhengyang

    2016-04-01

    Iron isotopes have been widely applied to interpret the fluid evolution, supergene alteration and the metallogenic material sources of the hydrothermal deposit. It may also have significant potentials on the research of the deposit. The Sandaowanzi telluride gold deposit, located in the Great Hinggan Range metallogenic Belt in NE China, is a large epithermal gold deposit of low-sulphidation type. It has a total reserve of ≥25t of Au and an average of 15 g/t. Gold-bearing quartz veins or gold lodes strike to the NW and dip 50-80°northeastward. Ore bodies, including low-grade ores along margins and high-grade ores in the central parts, principally occur in quartz veins. More than the 95 percent Au budgets are hosted in gold-silver tellurides. A six-stage paragenetic sequence of mineralization is revealed according to the compositions and microstructures of the mineral assemblages. Although sulfide minerals in the bonanza quartz veins are rare, pyrite are widespread in quartz veins and altered host rocks. Meanwhile there are always chalcopyrite veins within bonanza quartz veins. Pyrite Fe isotope compositions from different levels (from +50m to +210m) of the main ore body of the Sandaowanzi gold ore deposit are investigated. There is an overall variation in δ57Fe values from -0.09 to +0.99 (av. 0.33). Among them, twenty three samples from different mining levels give positiveδ57Fe values, with the maximum positive value at the economic bonanza ores (level +130m). Four samples, however, possess negative values, one at level 170m, one at level 130m, and two at level 50m, respectively. The two negative values from the levels 170m and 130m are near the cores of the high grade ore body. The two negative values from the level 50m occur at one end of the lode ore body. The above data set shows that the δ57Fe values are not homogeneous at different levels of the ore body. On the other hand, a general trend for the positive values is that the highest δ57Fe value is

  4. Major Brazilian gold deposits - 1982 to 1999

    Science.gov (United States)

    Thorman, Charles H.; DeWitt, Ed; Maron, Marcos A.; Ladeira, Eduardo A.

    2001-07-01

    Brazil has been a major but intermittent producer of gold since its discovery in 1500. Brazil led the world in gold production during the 18th and early 19th centuries. From the late 19th century to the late 20th century, total mining company and garimpeiro production was small and relatively constant at about 5 to 8 t/year. The discovery of alluvial deposits in the Amazon by garimpeiros in the 1970s and the opening of eight mines by mining companies from 1983 to 1990 fueled a major boom in Brazil's gold production, exceeding 100 t/year in 1988 and 1989. However, garimpeiro alluvial production decreased rapidly in the 1990s, to about 10 t/year by 1999. Company production increased about tenfold from about 4 t/year in 1982 to 40 t in 1992. Production from 1992 to the present remained relatively stable, even though several mines were closed or were in the process of closing and no new major mines were put into production during that period. Based on their production history from 1982-1999, 17 gold mines are ranked as major (>20 t) and minor (3-8 t) mines. From 1982-1999, deposits hosted in Archean rocks produced 66% of the gold in Brazil, whereas deposits in Paleoproterozoic and Neoproterozoic rocks accounted for 19% and 15%, respectively. Deposits in metamorphosed sedimentary rocks, especially carbonate-rich rocks and carbonate iron-formation, yielded the great bulk of the gold. Deposits in igneous rocks were of much less importance. The Archean and Paleoproterozoic terranes of Brazil largely lack base-metal-rich volcanogenic massive sulfide deposits, porphyry deposits, and polymetallic veins and sedimentary exhalative deposits. An exception to this is in the Carajás Mineral Province.

  5. Gold deposits and occurrences of the Greater Caucasus, Georgia Republic: Their genesis and prospecting criteria

    Science.gov (United States)

    Kekelia, S.A.; Kekelia, M.A.; Kuloshvili, S.I.; Sadradze, N.G.; Gagnidze, N.E.; Yaroshevich, V.Z.; Asatiani, G.G.; Doebrich, J.L.; Goldfarb, R.J.; Marsh, E.E.

    2008-01-01

    trapping pressures of 0.2 to 0.5??kbar. Ore-forming fluids, with approximately 5 to 20??mol% non-aqueous gas, evolved from N2-dominant to CO2-dominant during evolution of the hydrothermal system. ??34S values of + 1 to + 4??? for ore-related sulfides at Zopkhito are consistent with a sedimentary rock source for the sulfur, and ??18O quartz measurements of 16 to 21??? are consistent with either a magmatic or metamorphic fluid. More than 60 gold-bearing lodes and placers in the Svaneti district occur along the thrust between the Southern Slope and Main Zones. Lode gold potential was first recognized in the historic placer district in the 1980s, with many auriferous quartz veins cutting Middle Jurassic igneous rocks. Brecciated veins in the 18??t Au Lukhra deposit cut a small granodioritic to dioritic stock; the latter intrudes Devonian schist immediately north of the thrust. Presently, there are three recognized ore zones in the deposit, with the most significant occurring over an area 140??m in length and 12??m-wide, with typical grades of 7 to 9??g/t Au. Reconnaissance fluid-inclusion studies of ore samples from the Lukhra deposit indicate minimum trapping temperatures of 220????C. Measurements of ??18Oquartz of about 10??? suggest buffering of isotopic composition by the igneous host rocks.

  6. Ore-forming fluids in the Dongping gold deposit, northwestern Hebei Province

    Institute of Scientific and Technical Information of China (English)

    FAN; Hongrui

    2001-01-01

    : 1435-1444.[11]Schwartz, M. O., Determining phase volumes of mixed CO2-H2O inclusions using microthermometric measurements, Mineral Deposita, 1989, 24: 43-47.[12]Brown, P. E., Hagemann, S. G., MacFlincor and its application to fluids in Archean lode-gold deposits, Geochimica et Cosmochimica Acta, 1995, 59: 3943-3952.[13]Fan Hongrui, Xie Yihan, Zhao Rui et al., Dual origins of Xiaoqinling gold-bearing quartz veins: Fluid inclusion evidences, Chinese Science Bulletin, 2000, 45(15): 1424-1430.[14]Chen Yanjing, Li Chao, Zhang Jing et al., Sr and O isotopic characteristics of porphyries in the Qinling molybdenum de-posit belt and their implication to genetic mechanism and type, Science in China, Ser. D, 2000, 43 (supp.): 82-94.[15]Zhang Fuxin, Chen Yanjing, Li Chao et al., Geological and geochemical character and genesis of the Jinlongshan-Qiuling gold deposits in Qinling orogen: Metallogenic mechanism of the Qinling-pattern Carlin-type gold deposits, Science in China, Ser. D, 2000, 43(supp.): 95-107.[16]Chen Yanjing, Guo Guangjun, Li Xin, Metallogenic geodynamic background of gold deposits in Granite-greenstone ter-rains of North China craton, Science in China Ser. D, 1998, 41(2): 113-120.[17]Clayton, R. N., Oxygen isotope exchange between quartz and water, J. Geophys. Res., 1972, 77: 3057-3607.[18]Zhang Ligang, Cheng Zhengshen, Liu Jingxiu et al., Two Stage Water-rock Interaction and Prospecting Cases, Beijing: Geological Publishing House, 1995, 1-231.[19]Jiang Sihong, Nie Fengjun, 40Ar-39Ar geochronology of the Shuiquangou alkaline complex and related gold deposits, Northwestern Hebei, China, Geological Review, 2000, 46(6): 621-627.[20]Taylor, H. P., Oxygen and hydrogen isotope relationships, in Barnes H L(ed.), Geochemistry of Hydrothermal Ore Depos-its, 2nd ed., New York: John Wiley & Sons, 1979, 236-277.[21]Yardley, B. W. D., Post-metamorphic gold-quartz veins from N.W Italy: The composition and origin of the ore fluid, Min

  7. Gold deposits of the northern margin of the North China craton: Multiple late Paleozoic-Mesozoic mineralizing events

    Science.gov (United States)

    Hart, C.J.R.; Goldfarb, R.J.; Qiu, Y.; Snee, L.; Miller, L.D.; Miller, M.L.

    2002-01-01

    The northern margin of the North China craton is well-endowed with lode gold deposits hosting a resource of approximately 900 tonnes (t) of gold. The ???1,500-km-long region is characterized by east-trending blocks of metamorphosed Archean and Proterozoic strata that were episodically uplifted during Variscan, Indosinian, and Yanshanian deformational and magmatic events. At least 12 gold deposits from the Daqinshan, Yan-Liao (includes the Zhangjiakou, Yanshan, and Chifeng gold districts), and Changbaishan gold provinces contain resources of 20-100 t Au each. Most deposits are hosted in uplifted blocks of Precambrian metamorphic rocks, although felsic Paleozoic and Mesozoic plutons are typically proximal and host ???30% of the deposits. The lodes are characterized by sulfide-poor quartz veins in brittle structures with low base metal values and high Au:Ag ratios. Although phyllic alteration is most common, intensive alkali feldspar metasomatism characterizes the Wulashan, Dongping, and Zhongshangou deposits, but is apparently coeval with Variscan alkalic magmatism only at Wulashan. Stepwise 40Ar-39Ar geochronology on 16 samples from gangue and alteration phases, combined with unpublished SHRIMP U-Pb dates on associated granitoids, suggest that gold mineralizing events occured during Variscan, Indosinian, and Yanshanian orogenies at circa 350, 250, 200, 180, 150, and 129 Ma. However, widespread Permo-Triassic (???250 Ma) and Early Jurassic (???180 Ma) thermal events caused variable resetting of most of the white mica and K-feldspar argon spectra, as well as previously reported K-Ar determinations. Compiled and new stable isotope and fluid inclusion data show that most ??18O values for ore-stage veins range from 8 to 14???, indicating a fluid in equilibrium with the Precambrian metamorphic basement rocks; ??D values from fluid inclysions range widely from -64 to -154???, which is indicative of a local meteoric component in some veins; and highly variable ??34S data

  8. Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

    Science.gov (United States)

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

    2011-01-01

    Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays

  9. Geology and geochemistry of the shear-hosted Julie gold deposit, NW Ghana

    Science.gov (United States)

    Amponsah, Prince Ofori; Salvi, Stefano; Béziat, Didier; Siebenaller, Luc; Baratoux, Lenka; Jessell, Mark W.

    2015-12-01

    The Leo Man Craton in West Africa is host to numerous economic gold deposits. If some regions, such as the SW of Ghana, are well known for world-class mineralizations and have been extensively studied, gold occurrences elsewhere in the craton have been discovered only in the last half a century or so, and very little is known about them. The Julie gold deposit, located in the Paleoproterozoic Birimian terrane of NW Ghana, is one such case. This deposit is hosted in a series of granitoid intrusives of TTG composition, and consists of a network of deformed, boudinaged quartz lodes (A-type veins) contained within an early DJ1 E-W trending shear zone with dextral characteristics. A conjugate set of veins (C-type) perpendicular to the A-type veins contains low grade mineralization. The main ore zone defines a lenticular corridor about 20-50 m in width and about 3.5 km along strike, trending E-W and dipping between 30 and 60°N. The corridor is strongly altered, by an assemblage of sericite + quartz + ankerite + calcite + tourmaline + pyrite. This is surrounded by a second alteration assemblage, consisting of albite + sericite + calcite + chlorite + pyrite + rutile, which marks a lateral alteration that fades into the unaltered rock. Mass balance calculations show that during alteration overall mass was conserved and elemental transfer is generally consistent with sulfidation, sericitization and carbonatization of the host TTG. Gold is closely associated with pyrite, which occurs as disseminated grains in the veins and in the host rock, within the mineralized corridor. SEM imagery and LA-ICP-MS analyses of pyrites indicate that in A-type veins gold is associated with bismuth, tellurium, lead and silver, while in C-type veins it is mostly associated with silver. Pyrites in A-type veins contain gold as inclusions and as free gold on its edges and fractures, while pyrites from C-type veins contains mostly free gold. Primary and pseudosecondary fluid inclusions from both

  10. Metal and fluid sources in a potential world-class gold deposit: El-Sid mine, Egypt

    Science.gov (United States)

    Helmy, Hassan; Zoheir, Basem

    2015-04-01

    Lode gold mineralization at the El-Sid mine area is associated with the ca. 600 Ma Fawakhir granite intrusion, which cuts the ~737 Ma ophiolite nappes in the Central Eastern Desert of Egypt. The mineralized quartz veins are hosted by ~E- and NE-trending fault/fracture sets cutting the western boundary of the intrusion and sheared ophiolites. The results of electron microprobe analyses of gold-associated hydrothermal sulfide and silicate minerals suggest that Au was mobilized alongside Ni, Co, Cr and As from the adjacent ophiolitic serpentinite. After granite emplacement, hydrothermal fluids interacted with the sheared serpentinite, leaching metals and re-depositing them in the faults/fractures and adjacent wall rock in a cyclic process. Low-salinity aqueous-carbonic fluids with significant quantities of volatile species (CO2, CH4, and N2 ± H2S) leached and transported Au from deep to shallow crustal levels. Carbon dioxide had a buffering effect on the Au-bearing hydrothermal solution, maintaining its pH within a narrow near-neutral range, where elevated gold concentration was transported by complexation with reduced magmatic sulfur in a reducing environment. Gold deposition along fault/fracture conduits in the Fawakhir granite and adjacent serpentinite resulted from interplay of pressure drop, fluctuations in oxygen and sulfur fugacities, and exsolution of the volatile phases. Infiltration of meteoric water may have contributed to the formation of the late stage gold-sulfide mineralization that formed at shallower levels during terrane uplift. Sulfidation of the Fe-rich magmatic minerals was, on the other hand, the overriding process in the wall rock as evidenced by abundant disseminated sulfides with gold inclusions. Considering the structural control by regional shear zones (fluid conduits) and the voluminous granitic and ophiolitic rocks (metal sources), a high tonnage gold deposit amenable to open pit mining at the El-Sid mine area is very likely.

  11. A New Genetic Type of Gold Deposits-Meso-Epithermal Carbonate-Type Gold Deposits as Exemplified by the Baguamiao Suprlarge Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Gold deposits of the meso-epithermal carbonate type were first proposed based on the study of the Baguamiao gold deposit.This new type of gold deposits has many unique characteristics as follows:(1)Obviously strata-bound.The gold deposits are hosted in Middle Devonian turbidite formations;(2)Structrually controlled.Struc-ture is an important factor leading to metallogenesis of this type of gold deposits.The shape and distribution of orebodies are controlled by byittle-ductile shear zones;(3)Multi-stage wall-rock alteration.According to the characteristics of mineral assemblage,gold mineralization can be classified into three stages in association with various wall-rock al-terations.Wall-rock alterations closely genetically related to the gold mineralization are ankerization ,silicification,pyrrhotization and pyritization ;(4)Mineral compositions of the orebodies are mainly pyrrhotite,pyrite,marcasitolite,chalcopyrite,quartz,ankerite,and sericite.Gold mineralization is associated closely in space and time with iron sulfides;(5)Rare elements and REE in ores are low in contents relative to those of the crust.Au content varies from 1.91g/t to 11.15g/t ,averaging 5.5g/t;(6)Studies of sulfur,hydrogen,oxygen and carbon isotopes in main gangue minerals (quartz and ankerite)indicate that fluids and ore-forming materials came from deep-seated sources;(7)Three types of inclusions are recognized in terms of their composition and the vapor amounts of inclusions.The homogenization temperatures of inclusions range from 210℃to 310℃,averaging 230℃,showing that this type of gold deposits belongs to the meso-epithermal type;(8)Metallogenic age of this type of gold deposits is similar to that of the collision between the Yangtze Plate and the North China Plate,indicating that gold deposits of this type are genetically related to continental-margin plate activity.

  12. Geology of the world-class Kiaka polyphase gold deposit, West African Craton, Burkina Faso

    Science.gov (United States)

    Fontaine, Arnaud; Eglinger, Aurélien; Ada, Koumangdiwè; André-Mayer, Anne-Sylvie; Reisberg, Laurie; Siebenaller, Luc; Le Mignot, Elodie; Ganne, Jérôme; Poujol, Marc

    2017-02-01

    veinlets and D4 pervasive muscovite, ± chlorite, ± calcite in quartz-carbonate vein selvages and associated with pyrrhotite + arsenopyrite ± electrum, ± native gold and tellurobismuthite. The latter stage (2) could be divided into two sub-stages based on mineralogy and crosscutting relationship. A weighted average Re-Os pyrrhotite age at 2157 ± 24 Ma (Re-Os age based on 3 replicates) constraints the timing of the disseminated gold stage and represents the first absolute age for gold mineralization in the Manga Fada N'Gourma area. The timing of gold at Kiaka may be also coeval with one of the two lode gold event at ∼ ca. 2.16-2.15 Ga and occurred concomitant with tectono-thermal activity during Eo-Eburnean orogeny. The study of the Kiaka gold deposit emphasizes the importance of a multi-scale and multidisciplinary approach (field observations, petrography geothermobarometry and geochronology) to decipher the polyphase character of some Paleoproterozoic gold deposits.

  13. Physicochemical Properties of Gold Nanostructures Deposited on Glass

    Directory of Open Access Journals (Sweden)

    Zdenka Novotna

    2014-01-01

    Full Text Available Properties of gold films sputtered onto borosilicate glass substrate were studied. UV-Vis absorption spectra were used to investigate optical parameters. XRD analysis provided information about the gold crystalline nanostructure, the texture, and lattice parameter and biaxial tension was also determined by the XRD method. The surface morphology was examined by atomic force microscopy (AFM; chemical structure of sputtered gold nanostructures was examined by X-ray photoelectron spectroscopy (ARXPS. The gold crystallites are preferentially [111] oriented on the sputtered samples. Gold deposition leads to dramatic changes in the surface morphology in comparison to pristine glass substrate. Oxygen is not incorporated into the gold layer during gold deposition. Experimental data on lattice parameter were also confirmed by theoretical investigations of nanoclusters using tight-binding potentials.

  14. Magmatism and Epithermal Gold-Silver Deposits of the Southern Ancestral Cascade Arc, Western Nevada and Eastern California

    Science.gov (United States)

    John, David A.; du Bray, Edward A.; Henry, Christopher D.; Vikre, Peter

    2015-01-01

    Many epithermal gold-silver deposits are temporally and spatially associated with late Oligocene to Pliocene magmatism of the southern ancestral Cascade arc in western Nevada and eastern California. These deposits, which include both quartz-adularia (low- and intermediate-sulfidation; Comstock Lode, Tonopah, Bodie) and quartz-alunite (high-sulfidation; Goldfield, Paradise Peak) types, were major producers of gold and silver. Ancestral Cascade arc magmatism preceded that of the modern High Cascades arc and reflects subduction of the Farallon plate beneath North America. Ancestral arc magmatism began about 45 Ma, continued until about 3 Ma, and extended from near the Canada-United States border in Washington southward to about 250 km southeast of Reno, Nevada. The ancestral arc was split into northern and southern segments across an inferred tear in the subducting slab between Mount Shasta and Lassen Peak in northern California. The southern segment extends between 42°N in northern California and 37°N in western Nevada and was active from about 30 to 3 Ma. It is bounded on the east by the northeast edge of the Walker Lane. Ancestral arc volcanism represents an abrupt change in composition and style of magmatism relative to that in central Nevada. Large volume, caldera-forming, silicic ignimbrites associated with the 37 to 19 Ma ignimbrite flareup are dominant in central Nevada, whereas volcanic centers of the ancestral arc in western Nevada consist of andesitic stratovolcanoes and dacitic to rhyolitic lava domes that mostly formed between 25 and 4 Ma. Both ancestral arc and ignimbrite flareup magmatism resulted from rollback of the shallowly dipping slab that began about 45 Ma in northeast Nevada and migrated south-southwest with time. Most southern segment ancestral arc rocks have oxidized, high potassium, calc-alkaline compositions with silica contents ranging continuously from about 55 to 77 wt%. Most lavas are porphyritic and contain coarse plagioclase

  15. Puziwan Gold Deposit in Shanxi, China:A Special Linear Cryptoexplosive Breccia Type Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Puziwan gold deposit is a special linear cryptoexplosive breccia type deposit found in northeastern Shanxi, China, in recent years. The deposit is located in a secondary metallogenic belt of the most famous Au-Ag polymetallic metallogenic belt along the north margin of the North China platform. The secondary metallogenic belt is a synmagmatic tension-shear fault-fracture belt of ENE linear trend. The Indosinian cryptoexplosive breccia body, quartz monzonitic porphyry (beschtauite breccia), quartz monzonite (243.7 Ma, K-Ar), Yanshanian granite-porphyry (105± 6 Ma, Rb-Sr) and orebodies mostly occur as dykes or veins and short lenses along the structural fracture belt. The orebodies are emplaced in the fractured cryptoexplosive breccia body in the tectonomagmatic belt and their attitude is consistent with that of the breccia body. The orebodies have two types: one is shallow-seated thick and big ones, which are short-lenticular in plan and wedge-shaped in cross section, shallow buried, large in size and high-grade; the other is lean orebodies, which occur as parallel veins at depths. The ores are mainly of Au-Ag polymetallic sulphide-rich breccia type. Pyrite (limonite) is the dominant metallic mineral, with subordinate chalcopyrite, galena, sphalerite, tenantite, native gold, electrum, native silver and argentite. The gangue minerals consist mainly of quartz and plagioclase, with subordinate carbonate minerals, alunite chalcedony and kaolin. Kaolinization is the characteristic alteration type. Sulphide minerals contain abundant trace minerals such as Cu, Pb, Ag, Sb and Hg, while in the ores Ag, Cu, Pb, Zn, As and Sb are the best indicator element assemblage of Au. The δ34S(‰ values of the ores range from - 3.2‰to 5.3‰ with average - 0.102‰ The δOH2O(‰ and δD(‰ values are in the ranges from - 3.1‰to 7.73‰and from - 64‰to - 90‰respectively. The Pb isotopic compositions of the rocks and ores in this region indicate that Pb comes from three

  16. Origin of ore-forming fluids of the Haigou gold deposit in the eastern Central Asian Orogenic belt, NE China: Constraints from H-O-He-Ar isotopes

    Science.gov (United States)

    Zeng, Qingdong; He, Huaiyu; Zhu, Rixiang; Zhang, Song; Wang, Yongbin; Su, Fei

    2017-08-01

    The Haigou lode deposit contains 40 t of gold at an average grade of 3.5 g/t, and is one of the largest deposits in the Jiapigou gold belt located along the eastern segment of the northern margin of the North China Craton. The deposit comprises 15 gold-bearing quartz veins hosted in a Carboniferous monzonite-monzogranite stock. Cretaceous dikes consisting of diorite, diabase, and granodiorite porphyries are well developed in the deposit. The diorite porphyry dikes (130.4 ± 6.3 Ma) occur together with gold-bearing quartz veins in NNE- and NE-striking faults. Gold-bearing quartz veins crosscut the diorite porphyry dikes, and the veins are in turn crosscut by E-W-striking 124.6 ± 2.2 Ma granodiorite porphyry dikes. The mineralization mainly occurs as auriferous quartz veins with minor amounts of sulfide minerals, including pyrite, galena, chalcopyrite, and molybdenite. Gold occurs as either native gold or calaverite. Common gangue minerals in the deposit include quartz, sericite, and calcite. The deposit is characterized by various types of hydrothermal alteration, including silicification, sericitization, chloritization, potassic alteration, and carbonatization. Three stages of hydrothermal activity have been recognized in the deposit: (1) a barren quartz stage; (2) a polymetallic sulfide (gold) stage; (3) a calcite stage. Fluid inclusions in hydrothermal pyrites have 3He/4He ratios of 0.3 to 3.3 Ra and 40Ar/36Ar ratios of 351 to 1353, indicating mixing of fluids of mantle and crustal origin. Hydrothermal quartz yielded δ18O values of -1.3‰ to +7.2‰ and δD values of fluid inclusions in the quartz vary between -80‰ and -104‰. These stable isotope data also suggest mixing of magmatic and meteoric fluids. Noble gas and stable isotopic data suggest that the ore fluids have a predominant mantle source with a significant crustal component. Based on the spatial association of gold-bearing quartz veins with early Cretaceous intrusions, and the H-O-He-Ar isotopic

  17. Role of CO2 in the formation of gold deposits.

    Science.gov (United States)

    Phillips, G N; Evans, K A

    2004-06-24

    Much of global gold production has come from deposits with uneconomic concentrations of base metals, such as copper, lead and zinc. These 'gold-only' deposits are thought to have formed from hot, aqueous fluids rich in carbon dioxide, but only minor significance has been attached to the role of the CO2 in the process of gold transport. This is because chemical bonding between gold ions and CO2 species is not strong, and so it is unlikely that CO2 has a direct role in gold transport. An alternative indirect role for CO2 as a weak acid that buffers pH has also appeared unlikely, because previously inferred pH values for such gold-bearing fluids are variable. Here we show that such calculated pH values are unlikely to record conditions of gold transport, and propose that CO2 may play a critical role during gold transport by buffering the fluid in a pH range where elevated gold concentration can be maintained by complexation with reduced sulphur. Our conclusions, which are supported by geochemical modelling, may provide a platform for new gold exploration methods.

  18. Geology and Geochemistry of Reworking Gold Deposits in Intrusive Rocks of China—Ⅱ Gold Deposits and Their Genesis

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 程景平; 等

    1998-01-01

    Gold deposits in intrusive masses include the veinlet dissemination,quartz vein and veinlet dissemination+vein types,They are distributed in fracture zones along the endocontact zone of a batholith or in the centre and edge of a stock.The metallogenic epochs are Yenshanian,Hercynian,Archean,Proterozoic and Himalayan,The gold deposits are characterized by a big difference in time span between gold mineralization and the formation of host masses Ore-forming materials were derived from the masses and auriferous strata and ore-forming fluids came from meteoric and formation waters.When circulating water was heated by ascending heat flow,gold would be extracted,concentrated and transported from auriferous rocks and then precipitated in the masses during the late tectonic movement,Finally gold deposits were formed in the intrusive masses.

  19. Genesis of Gold- Silver Deposits in Qingchengzi Ore Field

    Institute of Scientific and Technical Information of China (English)

    Wei Min

    2001-01-01

    The gold - silver complex ore field of Qingchengzi is located in Liaohe group of Liaodong rift. The gold - silver ore bodies mainly lie in Dashiqiao group and Gaixian group, which provides ore - forming materials for the mineralization. For taking place multi - period and multi - stage magmatic activities, the ore - forming materials in the formation had had dynamothermal metamorphism for a long time and enriched and formed ore bodies after magmatism in Indo- Chinese and Yanshan epoch. The ore bodies are controlled by stratigraphic formation and stored in the interformational faults and schistosity belts. Silicalite is the most important indicator for searching them. Although the Pb - Zn and the gold - silver deposits are the same series of mineralized products, their positions are different, resulting from the differences of elements nature and mineralized conditions. The gold silver deposits belong to strata - bound and hysterogenetic mesothermal - epithermal deposit.

  20. Solid gold nanostructures fabricated by electron beam deposition

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Madsen, Dorte Nørgaard; Rasmussen, A.M.

    2003-01-01

    Direct writing with gold by electron beam deposition is a method for rapid fabrication of electrically conducting nanostructures. An environmental scanning electron microscope (ESEM) equipped with a source of the precursor gas dimethylacetylacetonate gold(Ill) was used to fabricate nanoscale tips...... and bridges. Transmission electron microscopy was used to study how the composition of these structures was affected when the background gas in the ESEM chamber and the electron beam parameters were varied. The nanostructures were layered composites of up to three different materials each characterized...... by a certain range of gold/carbon ratios. Above a certain threshold of ESEM chamber water vapor pressure and a certain threshold of electron beam current, the deposited tips contained a solid polycrystalline gold core. The deposition technique was used to fabricate free-standing nanowires and to solder free...

  1. Electron-beam-induced deposition of gold from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Schardein, G; Donev, E U; Hastings, J T, E-mail: hastings@engr.uky.edu [Department of Electrical and Computer Engineering and Center for Nanoscale Science and Engineering (CeNSE), University of Kentucky, Lexington, KY 40506 (United States)

    2011-01-07

    Focused electron-beam-induced deposition (EBID) using bulk liquid precursors is a novel approach to nanofabrication that has shown improvements in purity compared to EBID with gas-phase precursors. Here we report the first EBID of gold using bulk liquid precursors. We study the differences in gold deposited from three different aqueous solutions containing chloroauric acid (HAuCl{sub 4}), sodium tetrachloroaurate (NaAuCl{sub 4}), and the disulfitoaurate complex ([Au(SO{sub 3}){sub 2}]{sup 3-}). We also examine the dependence of threshold dose upon precursor concentration and demonstrate high-resolution patterning with a pitch as small as 50 nm. Finally, we show that the purity of gold deposited using these liquid precursors is significantly improved in comparison with deposits from metal-organic gaseous precursors.

  2. Experimental Study on Gold Dissolution from Hosting Minerals of the Hadamengou Gold Deposit and the Implications

    Institute of Scientific and Technical Information of China (English)

    LI Qiangzhi; YAN Fengzeng; WANG Xinhu

    2008-01-01

    The Hadamengou gold deposit is located in western part of the northern margin of the NorthChina craton. It is a hydrothermai deposit related to alkaline magmatism. Dissolution of Au, Fe frompyrite and iron oxide (including magnetite and hematite) individual minerals in the three main types ofore shows: in iron oxides (magnetite and hematite), Au and Fe were dissolved simultaneously and theirsolubilities are positively correlated, which means Au is mainly chemical-bonded (lattice gold) and/orcolloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behindFe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainlyhosted as grains of elemental gold (or native gold) within pyrite. Previous studies revealed that theHadamengou gold deposit is characterized by intensive K-feldspathization and holds high content ofiron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluidsunder a stretching geodynamic setting. These geological features, together with the high Au-content iniron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that thisdeposit is the first example of iron oxide-type gold deposits in China.

  3. A Study on the Relations Between Ultrabasic Dikes and Fine Disseminated Gold Deposits in Southwestern Guizhou Province as Exemplified by Zimudang Large—Sized Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    朱赖民

    1998-01-01

    The relations between ultrabasic rocks and gold deposits in time,space and genesis are discussed in this paper,the research results show that the ore-forming materials of the gold deposits is characteristic of crust-mantle mixing,The formation of the gold deposits is related with the activity of juvenile fluids along with the intrusion of ultrabasic dikes.The ascending juvenile fluids not only offered part of the gold.water and mineralizers for gold mineralization but also promoted the remobilization,deposition and enrichment of gold in crustal sediments.

  4. The physical hydrology of magmatic-hydrothermal systems: High-resolution 18O records of magmatic-meteoric water interaction from the Yankee Lode tin deposit (Mole Granite, Australia)

    Science.gov (United States)

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

    2016-04-01

    Magmatic-hydrothermal ore deposits are important economic Cu, Au, Mo and Sn resources (Sillitoe, 2010, Kesler, 1994). The ore formation is a result of superimposed enrichment processes and metals can precipitate due to fluid-rock interaction and/or temperature drop caused by convection or mixing with meteoric fluid (Heinrich and Candela 2014). Microthermometry and LA-ICP MS trace element analyses of fluid inclusions of a well-characterized quartz sample from the Yankee Lode quartz-cassiterite vein deposit (Mole Granite, Australia) suggest that tin precipitation was driven by dilution of hot magmatic water by meteoric fluids (Audétat et al.1998). High resolution in situ oxygen isotope measurements of quartz have the potential to detect changing fluid sources during the evolution of a hydrothermal system. We analyzed the euhedral growth zones of this previously well-studied quartz sample. Growth temperatures are provided by Audétat et al. (1998) and Audétat (1999). Calculated δ 18O values of the quartz- and/or cassiterite-precipitating fluid show significant variability through the zoned crystal. The first and second quartz generations (Q1 and Q2) were precipitated from a fluid of magmatic isotopic composition with δ 18O values of ˜ 8 - 10 ‰. δ 18O values of Q3- and tourmaline-precipitating fluids show a transition from magmatic δ 18O values of ˜ 8 ‰ to ˜ -5 ‰. The outermost quartz-chlorite-muscovite zone was precipitated from a fluid with a significant meteoric water component reflected by very light δ 18O values of about -15 ‰ which is consistent with values found by previous studies (Sun and Eadington, 1987) using conventional O-isotope analysis of veins in the distal halo of the granite intrusion. Intense incursion of meteoric water during Q3 precipitation (light δ 18O values) agrees with the main ore formation event, though the first occurrence of cassiterite is linked to Q2 precipitating fluid with magmatic-like isotope signature. This

  5. The giant Kalgoorlie Gold Field revisited

    Institute of Scientific and Technical Information of China (English)

    Noreen Mary Vielreicher; David Ian Groves; Neal Jesse McNaughton

    2016-01-01

    The Neoarchaean Kalgoorlie Gold Field contains the giant Golden Mile and world-class Mt Charlotte deposits, which have been the subject of much research for over 100 years. The Golden Mile deposit is a complex array of ductile to brittle vein and breccia lodes that are predominantly hosted in the highly-fractionated Golden Mile Dolerite sill. The Fimiston lodes comprise an array of narrow lodes that evolved broadly syn- to late-formation of the regional D2 NW-trending foliation. The lodes are charac-terized by pyrite veinlets and disseminations, quartz veinlets and breccias, and banded quartz-carbonate veins with sericite, carbonate, and pyrite-dominated alteration. Bonanza Green-Leader, or Oroya-style, lodes, with grades in excess of 1000 g/t Au, are similar to the Fimiston-style lodes, but are character-ized by abundant visible gold, native tellurium and more abundant telluride minerals within roscoelite-bearing alteration zones. The arguably structurally younger Mt Charlotte-style lodes are characterized by a pipe-shaped, coarse-grained quartz, carbonate and scheelite vein-stockwork with distinct vertically-zoned, carbonate-sericite-albite-pyrite ? pyrrhotite dominant alteration assemblages around veins within Unit 8 of the Golden Mile dolerite and porphyry dykes. The network of steep-and gently-dipping extension and shear fracture-fill veins are associated with NE-trending fault sets that cross cut the regional NW-trend. The deposit area is intruded by swarms of porphyry dykes, including syn-volcanic mafic dykes, early and volumetrically most significant c. 2.67 Ga feldspar-phyric porphyry dykes, as well as later c. 2.66‒2.65 Ga calc-alkaline hornblende-phyric dykes associated with younger c. 2.65‒2.64 Ga lamprophyre dykes. All post-volcanic dykes have similar orientations to the Fimiston lodes. The feldspar dykes are clearly overprinted by all styles of mineralization, although the relationship between hornblende-phyric and lamprophyre dykes and gold

  6. The Physico-Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit, Southwest Hunan, China

    Institute of Scientific and Technical Information of China (English)

    谷俐; 杨华; 戴塔根; 刘利萍

    2002-01-01

    Experiments on water-rock interaction were carried out on wall-rock samples from the Mobin gold deposit, Southwest Hunan, China, with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution. Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit. Mobi lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sulphur ions at the concentration and composition of about [0.25M (NH4)2S + 1M NaCl]. The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃ .

  7. Paleoproterozoic Sediment- hosted Gold Deposits in Eastern Liaoning, Northeast China: Implications for Gold Exploration

    Institute of Scientific and Technical Information of China (English)

    Yang Dejiang

    2001-01-01

    Gold deposits in eastern Liaoning, northeast China are hosted in the middle and upper parts of a Paleoproterozoic volcanic - sedimentary succession, which consists of interlayered carbonates and fine - grained clastics. This paper discusses the geological features of ore - bearing formations, ore- controlling structures and metallogenetic characteristics. Analysis of ore - controlling factors suggested that the schists from the Gaixian formatyion, syngenetic faults and ductile shear zones are principal ore controls over mineralization and thereafter indicators for gold exploration.

  8. Study on Mineralization Age of Xiaoban Gold Deposit, Fujian Province

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Xiaoban gold deposit is a large-size deposit recently found in middle area of Fujian Province. It belongs to magmatic hydrothermal type occurred in Mayuan Group metamorphic rocks of Middle Proterozoic and is controlled by low angle fault (detachment) structures. The contents of Au in Mayuan Group metamorphic rocks, Caledonian-Indosinian deformed granite and early Yanshanian granite are higher with Au enrichment coefficient of 2.06-5.68, 5.11 and 6.67 than those in other geological bodies. And the higher enrichment coefficients (>2) of Ag, S, Sn and Te are similar to those of gold ore. Meanwhile, the distribution of Au in Mayuan Group metamorphic rocks and early Yanshanian granite with a low D-value (0.58 and 0.67) is favorable to gold mineralization. REE characteristics of gold ore, ratios of (LREE/HREE), (La/Sm)n, (Yb/Lu)n, (La/Tb)n and (Sm/Nd)n are similar to Mayuan Group metamorphic rocks, only non or little normal Eu abnormal of ore is dissimilar to metamorphic rocks. The δ(34S) of the gold ore, with a high homogenization, is (-4.7×10-3)-(-2.7×10-3). The study of inclusion indicates 180-249 ℃ of mineralization temperature, 3.69 %-11.81 % of salinities and 0.869-0.991 g/cm3 of densities of mineralization fluid. Based on hydrogen and oxygen isotope (δ(18O)=11.0×10-3-11.7×10-3, δ(D)=(-48×10-3)-(-62×10-3)) and initial w(87Sr)/w(86Sr) =0.715,combining to the analysis of geological history, regional metamorphism and magamtic activity, the authors confirm that the source for the ore fluid was mainly from magmatic, partly from metamorphic water, and with a little influence of meteoric water. Isotopic dating made on Rb-Sr isochron age of 182 Ma, by using alteration minerals of gold-ores from the deposit, indicates that the mineralization occurs in early Yanshanian epoch. This is close to the age of 187 Ma of the Anchun magmatite with a similar alteration and gold mineralization to the Xiaoban gold deposit. The age of early Yanshanian epoch of the Xiaoban

  9. Direct deposition of gold on silicon with focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Irradiation with ions at very low energies (below 500 eV) no longer induces a removal of substrate material, but the ions are directly deposited on the surface. In this way, gold has been deposited on silicon with focused ion beam exposure and the properties of the film have been investigated with atomic force microscopy and Auger electron spectroscopy. (author) 3 figs., 1 ref.

  10. A Prospecting Mineralogy Study:Arsenopyrite In Endogenetic Gold Deposits

    Institute of Scientific and Technical Information of China (English)

    LI Xiaomin; ZHANG Hongzhi

    2001-01-01

    Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphism, composition typomorphism, pyroelectricity typomorphism and so on, were established. The crystal form of arsenopyrite is simple, and the form symbols mainly are {101}, {120}, {210}, {140}, {230}, {012}, etc. The smaller groin and poor crystal form arsenopyrite indicates the better auriferous characteristics. The major elements (Fe, As and S) of gold- bearing arsenopyrite usually show Fe/As + S > 0.5, As/S< 1 which deviates from its theoretical value. The most important trace element is Au and next is Ag in arsenopyrite, and they often show the positive correlation. The pyroelectricity of arsenopyrite can reflect the mineralization epoch, and it also is related to the crystal form and granudarity.

  11. Spectroelectrochemistry of Silver Deposition on Single Gold Nanocrystals.

    Science.gov (United States)

    Chirea, Mariana; Collins, Sean S E; Wei, Xingzhan; Mulvaney, Paul

    2014-12-18

    We report the electrodeposition of metallic silver onto gold nanostars adsorbed to ITO electrodes. The electrochemical process was studied at the single particle level by correlated in situ dark field spectroscopy and scanning electron microscopy (SEM). Underpotential deposition avoids bulk silver formation on the ITO substrates. SEM proves that deposition occurs on all surfaces of the gold nanostars when polyvinylpyrrolidone (PVP) is stabilizing the nanostars or preferentially at the nanostar tips when the ligand is removed. The surface plasmon resonance blue-shifts by more than 100 nm following the formation of a 5 nm Ag film on PVP stabilized gold nanostars, moving the scattered color from the near-infrared to red or orange. The spectral shifts can be accurately modeled using finite element simulations. These results demonstrate that the morphology and composition of individual bimetallic nanocrystals can be engineered electrochemically.

  12. Identifying Predictors of Arsenic Bioavailability in Low-Sulfide, Quartz-Hosted Gold Deposits: Case Study at the Empire Mine State Historic Park, CA, USA

    Science.gov (United States)

    Foster, A. L.; Alpers, C. N.; Burlak Regnier, T.; Blum, A.; Petersen, E. U.; Basta, N. T.; Whitacre, S.; Casteel, S. W.; Kim, C. S.

    2016-12-01

    Introduction: This study addressed a need to identify geochemical and mineralogical parameters that are significantly correlated with arsenic bioavailability at historically-mined, low-sulfide, quartz-hosted ("lode") gold deposits. The study location was the Empire Mine State Historic Park (EMSHP), a site that is typical of many lode deposits in California in that arsenic is a primary contaminant of concern. Methods: A total of 25 large-volume sediment/mine waste samples were collected from sites in the EMSHP, homogenized, and dry sieved (solid-phase chemistry (XRF; n = 25); (4) quantitative mineralogy (n =25); (5) Bulk As- and iron (Fe) speciation (synchrotron X-ray absorption spectroscopy, XAS, n =19); (6) point-based micron-scale composition (electron microprobe, n =12); and (7) micron-scale mineralogical and compositional mapping (QEMSCAN, n = 12). The matrix of bivariate correlations among these datasets was evaluated using a cutoff criterion for significance of p < 0.05. Results:Arsenic bioavailability was positively and significantly correlated with the abundance of Fe (hydr)oxide, the relative abundance of As-bearing hydroxide and As concentration in Fe hydroxide (datasets 4, 5, and 6, respectively). The relative abundance of As associated with Al-bearing secondary minerals (determined by As-XAS) was also positively and significantly correlated with datasets (1) and (2), but the correlation quality was lower. The relative abundance of other arsenic-bearing secondary minerals (e.g., jarosite, calcium arsenate, arseniosiderite) as determined by As XAS had positive correlations with bioaccessibility and/or bioavailability, but the correlations were not statistically significant. We ascribe this result to the fact that these phases only occurred in a few samples, whereas As- bearing Fe (hydr)oxide occurrence was ubiquitous. Highly negative and significant correlations were also observed between the abundance of arsenic-bearing sulfide minerals (datasets 4, 5

  13. World-class Xincheng gold deposit:An example from the giant Jiaodong gold province

    Institute of Scientific and Technical Information of China (English)

    Liqiang Yang; Jun Deng; Ruipeng Guo; Lin’nan Guo; Zhongliang Wang; Binghan Chen; Xudong Wang

    2016-01-01

    The Jiaodong gold deposits are currently the most important gold resources (with Au reserves of>4000 t) in China, and the leading gold-producing country globally (with Au production of w428 t in 2013). Jiaodong is also considered as perhaps the only world-class to giant gold accumulation on the planet where relatively young gold ores (ca. 130e120 Ma) were deposited in rocks that are 2 Ga older. The Xincheng world-class high-grade gold deposit, with a proven reserve of >200 t gold, is one of the largest deposits in the giant gold province of the Jiaodong Peninsula. It is located in the northwestern part of the Jiaobei Uplift, and hosted by ca. 132e123 Ma Xincheng quartz monzonites and monzogranites. Ore zones are structurally controlled by the NE-trending and NW-dipping Jiaojia Fault and subsidiary faults, and are mainly restricted to the footwall of the fault. The dominant disseminated-and stockwork-style ores are associated with strong sericitization, silicification, sulfidation and K-feldspathization, and minor carbonate wallrock alteration halos. The four mineralization stages are pyriteequartzesericite (stage 1), quartzepyrite (stage 2), quartzepolysulfide (stage 3) and quartzecarbonate (stage 4). Gold occurs dominantly as electrum, with lesser amounts of sulfide-hosted native gold and rare native silver and argentite, normally associated with pyrite, chalcopyrite, galena and sphalerite:the latter with proven resources of about 105 t Ag, 713 t Cu, and 5100 t S. There are three types of ore-related fluid inclusions: type 1 aqueous-carbonate (H2OeCO2), type 2 aqueous (liquid H2O þ vapor H2O), and type 3 CO2 (liquid CO2 and vapor CO2) inclusions. Homogeni-zation temperatures range from 221 to 304 ?C for type 1 inclusions, with salinities of 2.4e13.3 wt.%NaCl eq., and bulk densities of 0.858e1.022 g/cm3. The d34SCDT values of hydrothermal sulfides are 4.3e10.6&and d18O values of hydrothermal quartz have a median value of 13.0&. dD values of fluid inclusions in

  14. Molecular dynamics simulation of gold cluster growth during sputter deposition

    Science.gov (United States)

    Abraham, J. W.; Strunskus, T.; Faupel, F.; Bonitz, M.

    2016-05-01

    We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metal cluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared with recently published experimental data for gold on polystyrene [M. Schwartzkopf et al., ACS Appl. Mater. Interfaces 7, 13547 (2015)]. While good agreement is found between the two, the simulations additionally provide valuable time-dependent real-space data of the surface morphology, some of whose details are hidden in the reciprocal-space scattering images that were used for the experimental analysis.

  15. Sulfur radical species form gold deposits on Earth.

    Science.gov (United States)

    Pokrovski, Gleb S; Kokh, Maria A; Guillaume, Damien; Borisova, Anastassia Y; Gisquet, Pascal; Hazemann, Jean-Louis; Lahera, Eric; Del Net, William; Proux, Olivier; Testemale, Denis; Haigis, Volker; Jonchière, Romain; Seitsonen, Ari P; Ferlat, Guillaume; Vuilleumier, Rodolphe; Saitta, Antonino Marco; Boiron, Marie-Christine; Dubessy, Jean

    2015-11-01

    Current models of the formation and distribution of gold deposits on Earth are based on the long-standing paradigm that hydrogen sulfide and chloride are the ligands responsible for gold mobilization and precipitation by fluids across the lithosphere. Here we challenge this view by demonstrating, using in situ X-ray absorption spectroscopy and solubility measurements, coupled with molecular dynamics and thermodynamic simulations, that sulfur radical species, such as the trisulfur ion S3(-), form very stable and soluble complexes with Au(+) in aqueous solution at elevated temperatures (>250 °C) and pressures (>100 bar). These species enable extraction, transport, and focused precipitation of gold by sulfur-rich fluids 10-100 times more efficiently than sulfide and chloride only. As a result, S3(-) exerts an important control on the source, concentration, and distribution of gold in its major economic deposits from magmatic, hydrothermal, and metamorphic settings. The growth and decay of S3(-) during the fluid generation and evolution is one of the key factors that determine the fate of gold in the lithosphere.

  16. A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits

    Science.gov (United States)

    Hofstra, Albert H.; John, David A.; Theodore, Ted G.

    2003-01-01

    This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98, issue 2, contains five papers that address regional aspects important to the genesis of gold deposits in northern Nevada and five papers that present detailed studies of epithermal deposits and districts. All of the regional papers are pertinent to Carlin-type gold deposits, because they address the age of mineralization (Arehart et al., 2003), origin and evolutionary history of the northwest-striking mineral belts that localize many deposits (Grauch et al., 2003), nature of the middle and lower crust below these mineral belts (Howard, 2003), district- to deposit-scale stream sediment and lithogeochemical anomalies (Theodore et al., 2003), and stratigraphy and structure of a district located along a northeast-striking lineament (Peters et al., 2003).

  17. Ore—Search Perspective for Superlarge Gold Deposits in the Jiaolai Basin of the Jiaodong Gold Metallogenetic Domain

    Institute of Scientific and Technical Information of China (English)

    张竹如; 陈世桢; 等

    2000-01-01

    There are three types of gold deposits in the Jiaodong gold metallogenetic domain.The strata-bound gold deposits are a new type,which occur in a hydrocarbon-dled double-source bed enriched in gold(Au 174ng/g) and organic carbon(0.007-4.225%),At diagenetic a d hydrotherrmal stages water and oil were simultaneously activated and the stratabound gold deposits were formed from interactions between water ,oil and rocks.In the late Yanshanian period,gold oreboides were enriched and enlarged in response to tectonmoagmatism and action of complex ore-forming hydrothermal solutions.As a results,it is highly expected to find suparlarge gold deposits and the Yanzi area is expected to be a perspective target area.

  18. Geochemical explorations for gold deposits at Goldfield, Nevada

    Science.gov (United States)

    Ashley, Roger P.; Keith, William J.

    1978-01-01

    The main problem in geochemical exploration for gold ore bodies in the 40 km2 hydrothermally altered area at Goldfield is to decide which of the many silicified ledges exposed are most likely to yield deposits with additional subsurface exploration. We conclude that the most efficient way to search for exploration targets is to collect rock samples from the ledges and analyze for the following elements in decreasing order of priority: gold, lead and silver, bismuth, and mercury. These elements form relict hypogene aureoles restricted to the ledges and are not appreciably redistributed during supergene leaching.

  19. Geochemistry of Rare Earth Elements in Aktishikan Gold Deposit, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    袁峰; 周涛发; 岳书仓

    2002-01-01

    The characteristics and the models of rare earth elements in the geolo gical bodies and the hydrothermal water balanced with the adamellite were compre h ensively studied in Aktishikan gold deposit,Nurt area of Altay,Xinjiang.And th e behavior of rare earth elements during metasomatic alteration was discussed by using the isocon method of Grant.The results show that the rare earth elements a re inert during metasomatic alteration,the hydrothermal water has no relation t o the magmatic water,and the gold material sources mainly stem from the wall rock.

  20. Characterization of primary geochemical haloes for gold exploration at the Huanxiangwa gold deposit, China

    NARCIS (Netherlands)

    Wang, Changming; Carranza, Emmanuel John M.; Zhang, Shouting; Zhang, Jing; Liu, Xiaoji Liu; Zhang, Da; Sun, Xiang; Duan, Cunji

    2013-01-01

    Recognition of primary geochemical haloes is one of the most important tools for exploring undiscovered mineral resources. This tool is being routinely applied in exploration programs at the Huanxiangwa gold deposit, Xiong'er Mountains, China. Sampling of unweathered rock for multi-element analysis

  1. Controls on gold deposits in Hoggar, Tuareg Shield (Southern Algeria)

    Science.gov (United States)

    Aissa, Djamal-Eddine; Marignac, Christian

    2017-03-01

    The Hoggar shield belongs to the 3000 km-long Pan-African Trans-Saharan belt that was formed in the Neoproterozoic, between 750 and 500 Ma by continental collision between the converging West African craton, Congo craton and Saharan Metacraton. More than 600 gold occurrences have been identified by ORGM, which are confined along North-South Pan-African megashear zones stretching some hundreds of kilometres long. Until now, no global classification and mineral paragenesis characterisation have been proposed for the Hoggar's gold mineralization. In this paper, we briefly review the main gold mineralization, in order to classify them and to highlight their characteristics and controls. According to field work, spectral, microscopic and microthermometric studies, these mineralization can be globally classified asorogenic type shear zone, which can subdivided into three main sub-types according to the degree of their relationships with the major Pan-African shear zones: (i) Ultramylonite-mylonite hosted including Tirek and Amesmessa, world class deposits; (ii) Granite hosted, including Tekouyat occurrence (iii) Volcano-sediment hosted including Tiririne and In Abbegui deposits. All the deposits are coeval and were formed at the end of the post-collisional stage (530-520 Ma). InHoggar, gold mineralization depend on a double control, first order giant sub-meridian shear zone control and the gold districts disposed in N40°-50°E corridors that may be interpreted as extensional. Indeed, the Hoggar gold province appears to have been controlled at all scales by the late transtensive reactivation of the Pan-African mega-shear zones, and by the correlative heat flux associated with the linear lithospheric delamination processes accompanying this reactivation; which are also responsible for the very lateHoggar magmatic events. At Amesmessa, gold deposition was promoted by the mixing of metamorphic fluids issued from the In Ouzzal Archean-Proterozoic basement with magmatic

  2. The Russell gold deposit, Carolina Slate Belt, North Carolina

    Science.gov (United States)

    Klein, T.L.; Cunningham, C.G.; Logan, M.A.V.; Seal, R.R.

    2007-01-01

    Gold deposits have been mined in the Carolina slate belt from the early 1800s to recent times, with most of the production from large mines in South Carolina. The Russell mine, one of the larger producers in North Carolina, is located in the central Uwharrie Mountains, and produced over 470 kg of gold. Ore grades averaged about 3.4 grams per tonne (g/ t), with higher-grade zones reported. The Russell deposit is interpreted to be a sediment-hosted, gold-rich, base-metal poor, volcanogenic massive sulfide deposit in which gold was remobilized, in part, during Ordovician metamorphism. The ore was deposited syngenetically with laminated siltstones of the late Proterozoic Tillery Formation that have been metamorphosed to a lower greenschist facies. The Tillery Formation regionally overlies subaerial to shallow marine rhyolitic volcanic and volcaniclastic rocks of the Uwharrie Formation and underlies the marine volcanic and sedimentary rocks of the Cid Formation. Recent mapping has shown that a rhyolitic dome near the Russell mine was extruded during the deposition of the lower part of the Tillery Formation, at about the same time as ore deposition. Relict mafic, rock fragments present in the ore zones suggest contemporaneous bimodal (rhyolite-basalt) volcanism. The maximum formation age of the Russell deposit is younger than 558 Ma, which is similar to that of the larger, well known Brewer, Haile, and Ridgeway deposits of South Carolina. Gold was mined from at least six zones that are parallel to the regional metamorphic foliation. These strongly deformed zones consist of northeast-trending folds, high-angle reverse faults, and asymmetric doubly plunging folds overturned to the southeast. The dominant structure at the mine is an asymmetric doubly plunging anticline with the axis trending N 45?? E, probably related to late Ordovician (456 ?? 2 Ma) regional metamorphism and deformation. Two stages of pyrite growth are recognized. Stage 1, primary, spongy pyrite, is

  3. Tribological characteristics of gold films deposited on metals by ion plating and vapor deposition

    Science.gov (United States)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1986-01-01

    The graded interface between an ion-plated film and a substrate is discussed as well as the friction and wear properties of ion-plated gold. X-ray photoelectron spectroscopy (XPS) depth profiling and microhardness depth profiling were used to investigate the interface. The friction and wear properties of ion-plated and vapor-deposited gold films were studied both in an ultra high vacuum system to maximize adhesion and in oil to minimize adhesion. The results indicate that the solubility of gold on the substrate material controls the depth of the graded interface. Thermal diffusion and chemical diffusion mechanisms are thought to be involved in the formation of the gold-nickel interface. In iron-gold graded interfaces the gold was primarily dispersed in the iron and thus formed a physically bonded interface. The hardness of the gold film was influenced by its depth and was also related to the composition gradient between the gold and the substrate. The graded nickel-gold interface exhibited the highest hardness because of an alloy hardening effect. The effects of film thickness on adhesion and friction were established.

  4. Comparison of the native antimony-bearing Paiting gold deposit, Guizhou Province, China, with Carlin-type gold deposits, Nevada, USA

    Science.gov (United States)

    Xie, Zhuo-Jun; Xia, Yong; Cline, Jean S.; Yan, Bao-Wen; Wang, Ze-Peng; Tan, Qin-Ping; Wei, Dong-Tian

    2017-01-01

    The Paiting gold deposit, Guizhou Province, China, has been regarded as a Carlin-type gold deposit by several researchers. Alteration and ore-related minerals from the Paiting deposit were examined, and results were compared with the Cortez Hills Carlin-type gold deposit, Nevada, USA. Similarities include the structural and stratigraphic controls on the orebodies in both deposits and the occurrence of invisible gold ionically bound in arsenian pyrite. Significant differences include the following: (1) The gold-bearing mineral in Nevada is arsenian pyrite. However, gold-bearing minerals in the Paiting deposit include arsenopyrite, arsenian pyrite, and trace pyrrhotite. Also, euhedral or subhedral gold-bearing arsenian pyrite at Paiting contains significantly less As, Cu, and Hg than gold-bearing pyrite from Nevada. (2) Alteration in the Paiting deposit displays significantly less decarbonatization. Instead, dolomite precipitation, which has not been described in Nevada deposits, is associated with deposition of gold-bearing sulfide minerals. (3) Stibnite and minor native antimony typify Paiting late-ore-stage minerals, whereas in Nevada, realgar, orpiment, and calcite are common late-ore-stage minerals. Precipitation of native antimony in the Paiting deposit reflects the evolution of a late-ore fluid with unusually low sulfur and oxygen fugacities. Some characteristics of the Paiting gold deposit, including formation of ore-stage dolomite and precipitation from CO2-rich ore fluids at temperatures in excess of 250 °C, are more typical of orogenic deposits than Nevada Carlin deposits. The presence of similarities in the Paiting deposit to both Carlin type and orogenic deposits is consistent with formation conditions intermediate to those typical of Carlin type and orogenic systems.

  5. Comparison of galvanic displacement and electroless methods for deposition of gold nanoparticles on synthetic calcite

    Indian Academy of Sciences (India)

    Chamarthi K Srikanth; P Jeevanandam

    2012-11-01

    Gold nanoparticles have been deposited on synthetic calcite substrate by galvanic displacement reaction and electroless deposition methods. A comparative study has shown that electroless deposition is superior compared to galvanic displacement reaction for uniform deposition of gold nanoparticles on calcite. Characterization of the samples, prepared by two different deposition methods, was carried out by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy (FE–SEM) and diffuse reflectance spectroscopy (DRS) measurements. FE–SEM studies prove that smaller nanoparticles of gold are deposited uniformly on calcite if electroless deposition method was employed and DRS measurements show the characteristic surface plasmon resonance of gold nanoparticles.

  6. Geology, Genetic Types and Metallogeny of Gold Deposits in the Eastern Tianshan, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    As a typical Palaeozoic island arc system, the eastern Tianshan area, Xinjiang, is different from eastern China but similar to the Meso-Cenozoic island arc metallogenic provinces along the coast of the Pacific Ocean in metallogenic environment, geology and geochemistry. Three types of gold deposits, ductile shear zone-hosted gold deposits (Kanggur `), magmatic hydrothermal gold deposits (Jinwozi) and volcanic- or subvolcanic-hosted gold deposits (Xitan and Mazhuangshan), have been identified in this area. Regionally, gold deposits are structurally controlled by the Kanggur Tag ductile shear zone, Shaquanzi fault, Hongliuhe fault and Yamansu fault. Generally, gold mineralization occurs in the transition zones from volcanic rocks to sedimentary rocks. The horizon bearing well-developed jasper is an important indicator for gold mineralization. Each of the three types of gold deposits has its distinctive metallogenic background and geological-geochemical characteristics.

  7. Mineral chemistry and isotope geochemistry of pyrite from the Heilangou gold deposit, Jiaodong Peninsula, Eastern China

    Institute of Scientific and Technical Information of China (English)

    Yutong Yan; Na Zhang; Shengrong Li; Yongsheng Li

    2014-01-01

    The Heilangou gold deposit is located in the northern QixiaePenglai gold belt, which is one amongst the three large gold belts in the eastern Shandong Province (Jiaodong Peninsula). The ore body has formed within the Guojialing granite. In this study, we report the mineral chemistry of pyrite, as well as the S, Pb, and HeO isotope data of the Heilangou gold deposit. The chemical composition of pyrite in the Heilangou gold deposit indicates that the associated gold deposit is a typical magmatic hydrothermal one. The geochemical signatures and crystal structure of pyrite show that the ore-forming materials have been derived from the crust. The S isotope data of the pyrites from Heilangou show an overall range from 5.5 to 7.8&and an average of 6.7&. The S isotope data in this deposit are similar to those from the deposits in the Jiaodong gold belt. The Pb and S isotope variations are small in the Heilangou gold deposit. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios are 17.4653e17.5958, 15.5105e15.5746 and 38.0749e38.4361, respec-tively. These data plot between the lower crust and the orogenic belt. The Pb isotope data in the Heilangou gold deposit are similar to those in the Linglong gold deposit. From the Qixia gold area (the Liukou and Majiayao gold deposits) to the MupingeRushan gold belt (Rushan gold deposit) to the ZhaoeYe gold belt (the Linglong, Sanshandao and Jiaojia gold deposits), the 206Pb/204Pb ratios progressively increase. The DeO isotope data obtained from quartz separates suggest that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters. These results suggest that the ore-forming elements were primarily from source fluids derived from the lower crust.

  8. Gold nanostructuring on Si substrate by selective electroless deposition.

    Science.gov (United States)

    Bhuvana, T; Kulkarni, G U

    2007-06-01

    Gold deposition on Si(111) substrates has been carried out by electroless process from KAuCl4 in a fluorinated solution and the resulting nanostructures have been characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Deposition carried out under normal plating conditions produces an Au film with (111) orientation. The effect of additives such as poly(vinylpyrrolidone) (PVP) and mercaptoundecanoic acid (MUA) to the plating solution has been examined. While PVP induces amorphous deposition, MUA gives rise to flat (111) oriented islands. In order to produce individual nanostructures, we made use of octadecyltrichlorosilane (OTS) as a masking agent and carried out electroless deposition with an intermittent dip in OTS. By varying the durations of dip in the two solutions, various Au nanostructures-islands, cellular networks, and nanowires are obtained.

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

    Science.gov (United States)

    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.

  10. Geochemical characteristics of pyrite in Duolanasayi gold deposit, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    CHEN Guodong; XIAO Huiliang; WANG Henian; ZHOU Jiyuan

    2005-01-01

    The Duolanasayi gold deposit, 60 km NW of Habahe County, Xinjiang Uygur Autonomous Region, is a mid-large-scale gold deposit controlled by brittle-ductile shearing, and superimposed by albitite veins and late-stage magma hydrothermal solutions. There are four types of pyrite, which are contained in the light metamorphosed rocks (limestone, siltstone), altered-mineralized rocks (chlorite-schist, altered albite-granite, mineralized phyllite), quartz veins and carbonatite veinlets. The pyrite is the most common ore mineral. The Au-barren pyrite is present mainly in a simple form and gold-bearing pyrite is present mainly in a composite form. From the top downwards, the pyrite varies in crystal form from {100} and {210}+{100} to {210}+{100}+{111} to {100}+{111}. Geochemical studies indicate that the molecular contents of pyrite range from Fe1.057S2 to Fe0.941S2. Gold positively correlates with Mn, Sr, Zn, Te, Pb, Ba and Ag. There are four groups of trace elements: Fe-Cu-Sr-Ag, Au-Te-Co, As-Pb-Zn and Mn-V-Ti-Ba-Ni-Cr in pyrite. The REE characteristics show that the total amount of REE (ΣREE) ranges from 32.35×10 -6 to 132.18×10 -6; LREE/HREE, 4.466-9.142; (La/Yb)N, 3.719-11.133; (Eu/Sm)N, 0.553-1.656; (Sm/Nd)N, 0.602-0.717; La/Yb, 6.26-18.75; δEu, 0.628-2.309; δCe, 0.308-0.816. Sulfur isotopic compositions (δ 34S=-2.46‰--7.02‰) suggest that the sulfur associated with gold mineralization was derived from the upper mantle or lower crust.

  11. Geological and geochemical character and genesis of the Jinlongshan-Qiuling gold deposits in Qinling orogen: Metallogenic mechanism of the Qinling-pattern Carlin-type gold deposits

    Institute of Scientific and Technical Information of China (English)

    张复新,陈衍景,李超Department; of; Geology,; Peking; University,; Beijing; 100871,; China; ,张静Department; of; Geology,; Peking; University,; Beijing; 100871,; China; ,马建秦,李欣Department; of; Geology,; Peking; University,; Beijing; 100871,; China

    2000-01-01

    The Qinling Carlin-type gold deposit belt is the second largest Carlin-type gold ore concentrated area in the world and occurs in Mesozoic intracontinental collisional orogen, contrasting to the Carlin-type gold deposits in the Basin and Range province in Cenozoic active continental margin of West America. With ore-forming ages focussed at the range of 197.45-129.45 Ma, its metallogenic geodynamic background was the decornpression-pyrogenation regime at the transition stage from collisional compression to extension, indicating that gold mineralization synchronized with the Mesozoic continental collision. Geochemical studies discover that ore fluids and materials mainly came from the Hercynian-lndosinian tectonic layer. Mesozoic intracontinental subduction of Hercynian-lndosinian association along the Shuanghe-Gongguan fault led to the formation of Jinlongshan-Qiuling gold deposits. Accordingly, the tectonic metallogenic model is established for Qinling-pattern Carlin-type gold deposits.

  12. The dilemma of the Jiaodong gold deposits: Are they unique?

    Directory of Open Access Journals (Sweden)

    Richard J. Goldfarb

    2014-03-01

    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 subduction, and seismicity along the continental-scale Tan-Lu fault. Possible ore genesis scenarios include those where ore fluids were produced directly by the metamorphism of oceanic lithosphere and overlying sediment on the subducting paleo-Pacific slab, or by devolatilization of an enriched mantle wedge above the slab. Both the sulfur and gold could be sourced from either the oceanic sediments or the serpentinized mantle. A better understanding of the architecture of the paleo-Pacific slab during Early Cretaceous below the eastern margin of China is essential to determination of the validity of possible models.

  13. Magnesium–Gold Alloy Formation by Underpotential Deposition of Magnesium onto Gold from Nitrate Melts

    Directory of Open Access Journals (Sweden)

    Vesna S. Cvetković

    2017-03-01

    Full Text Available Magnesium underpotential deposition on gold electrodes from magnesium nitrate –ammonium nitrate melts has been investigated. Linear sweep voltammetry and potential step were used as electrochemical techniques. Scanning electron microscopy (SEM, energy dispersive spectrometry (EDS and X-ray diffraction (XRD were used for characterization of obtained electrode surfaces. It was observed that reduction processes of nitrate, nitrite and traces of water (when present, in the Mg underpotential range studied, proceeded simultaneously with magnesium underpotential deposition. There was no clear evidence of Mg/Au alloy formation induced by Mg UPD from the melt made from eutectic mixture [Mg(NO32·6H2O + NH4NO3·XH2O]. However, EDS and XRD analysis showed magnesium present in the gold substrate and four different Mg/Au alloys being formed as a result of magnesium underpotential deposition and interdiffusion between Mg deposit and Au substrate from the melt made of a nonaqueous [Mg(NO32 + NH4NO3] eutectic mixture at 460 K.

  14. Metallogenic Features and Metalogenic Model of Laterite Gold Deposits in Southern China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The modern laterite gold deposits in southern China, which belong to reworked laterite deposits, can be further divided into three subclasses and seven types. Their geological features, ore-forming conditions and regularities are discussed. A geologic-geochemical metallogenic model for laterite gold deposits has been established.

  15. Ore-forming and Exploration Models of the Baguamiao Gold Deposit, Shaanxi Province

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Baguamiao superlarge gold deposit in Shaanxi Province is one of the typical cases in China that are hosted by sedimentary rocks. Explorers and researchers have discussed the gold mineralization enrichment conditions by studying sulphur, oxygen, carbon, silicon stable isotopes and mineralizing fluid features of the Baguamiao gold deposit and proposed a hydrothermal sedimentation-magmatic reconstructing gold mineralization model featuring multi-sources of ore-forming materials and multistage mineralizations. In addition, prospecting for "Baguamiao-type"gold deposits was started in the Fengtai Basin and a great number of important prospecting targets such as Tonglinggou, Simaoling, Guoansi and Dachaigou were discovered.

  16. The Deposition of Gold Nanoparticles Onto Activated Carbon

    Directory of Open Access Journals (Sweden)

    Jaworski W.

    2014-10-01

    Full Text Available This work reports the results of spectrophotometric, dynamic light scattering (DLS and microscopic (SEM studies of the gold nanoparticles (AuNPs deposition on activated carbon (AC surface modified with primary (ethanolamine and secondary (diethylenetriamine and triethylenetetramine amines. It was found that this method is efficient for deposition of AuNPs from aqueous solution. However, nanoparticles change their morphology depending on the kind of amine used in experiments. On the AC surface modified with ethanolamine, the uniform spherical AuNPs were formed. In case of diethylenetriamine and triethylenetetramine application, the agglomerates of AuNPs are present. The diameter of individual AuNPs did not exceed 15 nm and was bigger as compared with the diameter of particles present in precursor solution (ca. 10 nm.

  17. Geochemical Characteristics of Jinwozi Gold Deposit,Xinjiang

    Institute of Scientific and Technical Information of China (English)

    章振根; 陈南生

    1991-01-01

    The Jinwozi gold deposit consists of gold-bearing quartz veins in a biotite granodiorite of Hercynian age (Zircon U-Pb age≈335.7Ma).Ore mineralogy is simple .In addition to native gold,there are only small amounts of sulfides,meinly pyrite and minor sphalerite,chalcopyrite and galena.δ34S val-ues average 6.69‰,and δ18O13.99‰.Abundant CO2 is contained in fluid inclusions from quartz.Homogenization temperatures of fluid inclusions are between 186 and 262°.REE distribution pat-terns indicate that the igneous mass may have been derived from a common initial material of calcareous-argillaceous sediments and alkali basalts as the country rocks.In other words,the Jinwozi granodiorite is of remelting origin from crustal material.Isotopic evidence of S,O and Pb shows that the ore-forming material is genetically related to magmatic hydrothermal activity.

  18. Reactive pulsed laser deposition of gold nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P. [University of Salento, Department of Physics, 73100 Lecce (Italy); Fernandez, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Leggieri, G. [University of Salento, Department of Physics, 73100 Lecce (Italy)]. E-mail: leggieri@le.infn.it; Luches, A. [University of Salento, Department of Physics, 73100 Lecce (Italy); Martino, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Romano, F. [University of Salento, Department of Physics, 73100 Lecce (Italy); Tunno, T. [University of Salento, Department of Physics, 73100 Lecce (Italy); Valerini, D. [University of Salento, Department of Physics, 73100 Lecce (Italy); Verdyan, A. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Soifer, Y.M. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Azoulay, J. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Meda, L. [IGD Polimeri Europa S.p.A, Novara (Italy)

    2007-07-31

    We report on the growth and characterization of gold nitride thin films on Si <1 0 0> substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N{sub 2} or NH{sub 3}). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 deg. C. Film resistivity was measured using a four-point probe and resulted in the (4-20) x 10{sup -8} {omega} m range, depending on the ambient pressure, to be compared with the value 2.6 x 10{sup -8} {omega} m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N{sub 2} phase. All these measurements point to the formation of the gold nitride phase.

  19. Reactive pulsed laser deposition of gold nitride thin films

    Science.gov (United States)

    Caricato, A. P.; Fernàndez, M.; Leggieri, G.; Luches, A.; Martino, M.; Romano, F.; Tunno, T.; Valerini, D.; Verdyan, A.; Soifer, Y. M.; Azoulay, J.; Meda, L.

    2007-07-01

    We report on the growth and characterization of gold nitride thin films on Si substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N 2 or NH 3). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 °C. Film resistivity was measured using a four-point probe and resulted in the (4-20) × 10 -8 Ω m range, depending on the ambient pressure, to be compared with the value 2.6 × 10 -8 Ω m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N 2 phase. All these measurements point to the formation of the gold nitride phase.

  20. Clay alteration and gold deposition in the genesis and blue star deposits, Eureka County, Nevada

    Science.gov (United States)

    Drews-Armitage, S. P.; Romberger, S.B.; Whitney, C.G.

    1996-01-01

    The Genesis and Blue Star sedimentary rock-hosted gold deposits occur within the 40-mile-long Carlin trend and are located in Eureka County, Nevada. The deposits are hosted within the Devonian calcareous Popovich Formation, the siliciclastic Rodeo Creek unit and the siliciclastic Vinini Formation. The host rocks have undergone contact metamorphism, decalcification, silicification, argillization, and supergene oxidation. Detailed characterization of the alteration patterns, mineralogy, modes of occurrence, and associated geochemistry of clay minerals resulted in the following classifications: least altered rocks, found distal to the orebody, consisting of both metamorphosed and unmetamorphosed host rock that has not been completely decalcified; and altered rocks, found proximal to the orebody that have been decalcified. Altered rocks are classified further into the following groups based on clay mineral content: silicic, 1 to 10 percent clay; silicicargillic, 10 to 35 percent clay; and argillic, 35 to 80 percent clay. Clay species identified are 1M illite, 2M1 illite, kaolinite, halloysite, and dioctahedral smectite. An early hydrothermal event resulted in the precipitation of euhedral kaolinite and at least one generation of silica. This event occurred contemporaneously with decalcification which increased rock permeability and porosity. A second clay alteration event resulted in the precipitation of hydrothermal 1M illite which replaced hydrothermal kaolinite and is associated with gold deposition. Silver and silica deposition is also associated with this phase of hydrothermal alteration. Hydrothermal alteration was followed by supergene alteration which resulted in the formation of supergene kaolinite, halloysite, and smectite as well as the oxidation of iron-bearing minerals. Supergene clays are concentrated along faults, dike margins, and within rocks containing carbonate. Gold mineralization is not associated with supergene clay minerals within the Genesis and

  1. Origin of Gold-Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit, Shandong Province

    Institute of Scientific and Technical Information of China (English)

    邓军; 王庆飞; 孙忠实

    2002-01-01

    The composition of quartz inclusions and trace elements in ore indicate that gold bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold-bearing fluid initiative localization mechanism and the forming environment of ore-host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of its expanding and injecting forces and flew through ore-conducive structures, leading to the breakup of rocks. The generation of ore-host faults and the precipitation of gold-bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic-ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.

  2. Geochemical Study of Gold and Arsenic Mineralization of the Carlin-Type Gold Deposits, Qinling Region, China

    Institute of Scientific and Technical Information of China (English)

    张复新; 马建秦; 陈衍景

    2001-01-01

    Element geochemistry of gold and arsenic and mineralogical features of their sulfides in the Carlin-type gold deposits of the Qinling region are discussed in this paper. The initial contents of ore-forming elements such as gold and arsenic are high in the ore-bearing rock series in the Qinling region. Furthermore, both the metals are concentrated mainly in the diagenetic pyrite. Study on the mineralogy of arsenic-bearing sulfide minerals in the ores demonstrated that there is a positive correlation between gold and arsenic in the sulfide minerals. Available evidence suggests that gold in the As-bearing sulfide minerals is likely to be presented as a charge species (Au + ), and it is most possible for it to replace the excess arsenic at the site of iron and was probably deposited together with arsenic as solid solution in the sulfide minerals.Pyrite is composed of (Au3x+, Fe12-+ x) ([AsS]3x- [S2]12--x), and arsenopyrite of (Au3x+ , Fe13-+x)([AsS]3x- [AsS2 ]1-3-x). The occurrence of gold in the As-sulfide minerals from the Carlin-type gold deposits in the Qinling region has been confirmed by electron probe and transmission elec tron microscopic studies. The results show that gold was probably deposited together with ar senic as coupled solid solutions in sulfide minerals in the early stage of mineralization. Metallo genic chemical reactions concerning gold deposition in the Carlin-type As-rich gold deposits would involve oxidation of gold and concurrent reduction of arsenic. Later, the deposited gold as solid solution was remobilized and redistributed as exsolutions, as a result of increasing hy drothermal alteration and crystallization, and decreasing resistance to refractoriness of the host minerals. Gold occurs as sub-microscopic grains (ranging from 0.04 to 0.16 μm in diameter)of native gold along micro factures in and crystalline grains of the sulfides.

  3. Study on genesis of the primary orebody in Shewushan gold deposit

    Directory of Open Access Journals (Sweden)

    BASSANGANAM Narcisse

    2015-07-01

    Full Text Available Shewushan gold deposit is located at 16 km southwest of Jiayu County, Xianning City, Hubei Province, with approximately 10 Mt reserve and average around 2.2 g /t gold grade. That resulted from chemistry of carlin-type orebody hosted in Cambrian-Permian strata under tertiary tropical rainforest climate, which exposed to the oxidation interface by the regional uplift movement. Shewushan gold deposit is a closed negative terrain controlled by faults, where broad karst landform also developed in the fault and unconformity boundary, and obviously is a favorable environment for weathering gold deposit

  4. Surface-enhanced Raman scattering dendritic substrates fabricated by deposition of gold and silver on silicon.

    Science.gov (United States)

    Cheng, Mingfei; Fang, Jinghuai; Cao, Min; Jin, Yonglong

    2010-11-01

    This paper reports a study on the preparation of gold nanoparticles and silver dendrites on silicon substrates by immersion plating. Firstly, gold was deposited onto silicon wafer from HF aqueous solution containing HAuCl4. Then, the silicon wafer deposited gold was dipped into HF aqueous solution of AgNO3 to form silver coating gold film. Scanning electron microscopy reveals a uniform gold film consisted of gold nanoparticles and rough silver coating gold film containing uniform dendritic structures on silicon surface. By SERS (surface-enhanced Raman scattering) measurements, the fabricated gold and silver coating gold substrates activity toward SERS is assessed. The SERS spectra of crystal violet on the fabricated substrates reflect the different SERS activities on gold nanoparticles film and silver coating gold dendrites film. Compared with pure gold film on silicon, the film of silver coating gold dendrites film significantly increased the SERS intensity. As the fabrication process is very simple, cost-effective and reproducible, and the fabricated silver coating gold substrate is of excellent enhancement ability, spatial uniformity and good stability.

  5. Genetic Analogy Between Sediment—Hosted Gold Deposits and Sediment—Hosted Copper Deposits in Southwest China

    Institute of Scientific and Technical Information of China (English)

    肖荣阁; 陈卉泉; 等

    1996-01-01

    The sediment-hosted copper deposits according to the authors' study were formed from connate formation water during the post-sedimentary or diagenetic stage while the sediment-hosted disseminated gold deposits are unanimously considered to be of post-sedimentary hydrothermal origin.Therefore,apart from their own individulities.These two types of deposits must share some characters in common.Comparisons are attempted,in this paper,between the sediment-hosted copper deposits in southwest China and the Triassic sediment-hosted disseminated gold deposits in the Yunnan-Guizhou-Guangxi Triangle in terms of geological and geochemical features.

  6. Confirmation and Significance of Caledonian Metallogenic Epoch for Gold Deposits in South China

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 梁华英; 单强; 程景平; 夏萍

    2001-01-01

    Caledonian gold deposits are widely distributed in South China. They are developed in both South China Caledonian fold belt and adjacent Proterozoic Jiangnan uplift. The host rocks are Proterozoic metamorphosed microclastic rocks in the Jiangnan uplift and Proterozoic and Cambrian strata, as well as Chengjiang and Caledonian igneous bodies in the South China fold belt. The distinct differences between the Caledonian and the most developed Yenshanian gold deposits in South China are reflected in age and host-rock type, relations to Yenshanian magmatic activities, element association, mineral assemblage and gold deposit type. The stud ies have proven that the Caledonian epoch is a principal metallogenic period of gold deposits in South China. This conclusion is of very important enlightening significance in exploration of Caledonian gold deposits in South China as well as in other Caledonian fold belts and adjacent u plifts in China.

  7. The geology of the Morro Velho gold deposit in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil

    Science.gov (United States)

    Vial, Diogenes Scipioni; DeWitt, Ed; Lobato, Lydia Maria; Thorman, Charles H.

    2007-01-01

    The Morro Velho gold deposit, Quadrilátero Ferrífero region, Minas Gerais, Brazil, is hosted by rocks at the base of the Archean Rio das Velhas greenstone belt. The deposit occurs within a thick carbonaceous phyllite package, containing intercalations of felsic and intermediate volcaniclastic rocks and dolomites. Considering the temporal and spatial association of the deposit with the Rio das Velhas orogeny, and location in close proximity to a major NNW-trending fault zone, it can be classified as an orogenic gold deposit. Hydrothermal activity was characterized by intense enrichment in alteration zones of carbonates, sulfides, chlorite, white mica±biotite, albite and quartz, as described in other Archean lode-type gold ores. Two types of ore occur in the deposit: dark gray quartz veins and sulfide-rich gold orebodies. The sulfide-rich orebodies range from disseminated concentrations of sulfide minerals to massive sulfide bodies. The sulfide assemblage comprises (by volume), on average, 74% pyrrhotite, 17% arsenopyrite, 8% pyrite and 1% chalcopyrite. The orebodies have a long axis parallel to the local stretching lineation, with continuity down the plunge of fold axis for at least 4.8 km. The group of rocks hosting the Morro Velho gold mineralization is locally referred to as lapa seca. These were isoclinally folded and metamorphosed prior to gold mineralization. The lapa seca and the orebodies it hosts are distributed in five main tight folds related to F1 (the best examples are the X, Main and South orebodies, in level 25), which are disrupted by NE- to E-striking shear zones. Textural features indicate that the sulfide mineralization postdated regional peak metamorphism, and that the massive sulfide ore has subsequently been neither metamorphosed nor deformed. Lead isotope ratios indicate a model age of 2.82 ± 0.05 Ga for both sulfide and gold mineralization. The lapa seca are interpreted as the results of a pre-gold alteration process and may be

  8. Miocene and early Pliocene epithermal gold-silver deposits in the northern Great Basin, western United States: Characteristics, distribution, and relationship to Magmatism

    Science.gov (United States)

    John, D.A.

    2001-01-01

    -sulfidation gold-silver and porphyry copper-gold deposits are affiliated with the western andesite assemblage and include the Comstock Lode, Tonopah, Goldfield, Aurora, Bodie, Paradise Peak, and Rawhide deposits. Low-sulfidation Au-Ag deposits in the bimodal assemblage formed under relatively low oxygen and sulfur fugacities and have generally low total base metal (Cu + Pb + Zn) contents, low Ag/Au ratios, and notably high selenide mineral contents compared to temporally equivalent low-sulfidation deposits in the western andesite assemblage. Petrologic studies suggest that these differences may reflect variations in the magmatic-tectonic settings of the associated magmatic assemblages-deposits in the western andesite assemblage formed from oxidized, water-rich, subduction-related calc-alkaline magmas, whereas deposits in the bimodal assemblage were associated with reduced, water-poor tholeiitic magmas derived from the lithospheric mantle during continental extension. The contrasting types and characteristics of epithermal deposits and their affinities with associated igneous rocks suggest that a genetic relationship is present between these Au-Ag deposits and their temporally associated magmatism, although available data do not prove this relationship for most low-sulfidation deposits.

  9. Geochemistry of Main Types of Gold Deposits in Shear Zones,China

    Institute of Scientific and Technical Information of China (English)

    吴学益; 杨元根; 等

    1999-01-01

    Shear zone-hosted gold deposits in China can be divided into four types:ductile,brittle-ductile,ductile-brittle and brittle,of which the ductile and brittle types are the basic ones.All these types of gold deposits have their own geochemical characteristics.The Hetai gold deposit in Guangdong Province,for example,is a mylonite-type gold deposit in a ductile shear zone.With increasing mylonitization,obvious changes took place in trace elements in minerals and rocks,enriching gold and mineralizing elements.The S and Pb isotope data indicated that the ore-forming materials were derived from the strata.Hydrogen and oxygen isotopic and fluid inclusion studies also implied that the ore-forming fluid was much closer to meteoric water from the early to the late ore-forming stage.The Linglong gold deposit,Shangdong Province,is a quartz-type gold deposit in a brittle shear zone.Changes in rocks,minerals and trace elements occurred in the process of f ormation of gold quartz veins,and the analytical results of S,Pb ,Hand O isotopes showed that ore deposition is connected not only with the Jiaodong Group,but also with anatexic granites.

  10. Fabrication of arrays of gold islands on self-assembled monolayers using pulsed laser deposition through nanosieves

    NARCIS (Netherlands)

    Speets, Emiel A.; Ravoo, Bart Jan; Roesthuis, Frank J.G.; Vroegindeweij, Frank; Blank, Dave H.A.; Reinhoudt, David N.

    2004-01-01

    Sandwich structures of gold-self-assembled monolayer-gold were prepared by deposition of gold on alkylthiolate self-assembled monolayers on polycrystalline gold, using pulsed laser deposition (PLD) through a nanosieve. The arrays of sandwiches, around 600 nm in diameter, approximately 10 nm high, an

  11. 40Ar-39Ar dating and geologi-cal implication of auriferous altered rocks from the middle-deep section of Q875 gold-quartz vein in Xiaoqinling area, Henan, China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 40Ar-39Ar age method is employed in this work to analyze the aurif erous altered rocks from the middle-deep section of the Q875 gold-quartz vein in the Xiaoqinling area, and the results show that the main gold deposition of the Q875 occurred in ca. 128-126 Ma. As a typical gold-bearing quartz vein in this gold-rich area, the age data obtained from the Q875 also constrain on the metal logenic time of the lode gold deposits developed in the same geological settings . This geochronological study supplies new evidence for further understanding the timing of gold mineralization, the genesis of gold deposits and the geodynamic settings in Xiaoqinling area.

  12. Enhancement of R6G fluorescence by N-type porous silicon deposited with gold nanoparticles

    Science.gov (United States)

    Mo, Jia-qing; Jiang, Jing; Zhai, Zhen-gang; Shi, Fu-gui; Jia, Zhen-hong

    2017-01-01

    By the electrochemical anodization method, we achieve the single-layer macroporous silicon on the N-type silicon, and prepare gold nanoparticles with sodium citrate reduction method. Through injecting the gold nanoparticles into the porous silicon by immersion, the fluorescence quenching mechanism of porous silicon influenced by gold nanoparticles is analyzed. Then the macroporous silicon deposited with gold nanoparticles is utilized to enhance the fluorescence of rhodamine 6G (R6G). It is found that when the macroporous silicon is deposited with gold nanoparticles for 6 h, the maximum fluorescence enhancement of R6G (about ten times) can be realized. The N-type porous silicon deposited with gold nanoparticles can be an excellent substrate for fluorescence detection.

  13. Bismuth mineral inclusions in gold-bearing magnetite from the giant Beiya gold deposit, SW China: insights into mineralization process

    Science.gov (United States)

    Zhou, Haoyang; Sun, Xiaoming

    2017-04-01

    Bismuth minerals are commonly found in a wide range of gold deposits and could offer valuable information on the process of gold mineralization. This is because Bi minerals always show immediate association with gold and are sensitive to chemical-physical variations (Afifi et al., 1988). Specifically, native bismuth has a melting point of 271°C and could melt at lower temperatures when gold is added (Okamoto et al,, 1983). It has been verified that Bi melt could efficiently scavenge gold from hydrothermal fluids (Tooth et al., 2008, 2011). The Beiya deposit, situated in the Sanjiang Tethyan tectonic domain in the southwestern China, is one of the largest gold deposits in China 10.4 Moz Au @ 2.47g/t). Located along the contacts between a 36 Ma quartz syenite porphyry and the Triassic limestones, the deposit contains abundant massive Au-bearing magnetite ores, which are considered as a product of skarn mineralization. However, the pivotal processes accounting for the huge accumulation of gold resource at Beiya area are poorly constrained. In the massive magnetite ores, abundant native gold was observed to be present as submicron-scale inclusions hosted by magnetite (Zhou et al., 2017). We also noted that abundant Bi minerals occur within these ores (Zhou et al., 2016), which provide critical clues to reveal the processes of gold mineralization. An assemblage of Bi minerals, composed of native bismuth, maldonite and bismuthinite, is present as tiny inclusions in these Au-bearing magnetite grains. Mineralogical study illustrates the encapsulation of native bismuth and maldonite as melts during magnetite growth, which is also supported by the ore-forming temperatures over 300°C derived from previous fluid inclusions study (He et al., 2016). Our thermodynamic modeling demonstrates that Bi melts scavenged gold from hydrothermal fluids. Subsequently, sulfidation of Bi melts resulted in precipitation of gold, which was captured by growing magnetite. We thus propose that

  14. Directed deposition of silicon nanowires using neopentasilane as precursor and gold as catalyst

    Directory of Open Access Journals (Sweden)

    Britta Kämpken

    2012-07-01

    Full Text Available In this work the applicability of neopentasilane (Si(SiH34 as a precursor for the formation of silicon nanowires by using gold nanoparticles as a catalyst has been explored. The growth proceeds via the formation of liquid gold/silicon alloy droplets, which excrete the silicon nanowires upon continued decomposition of the precursor. This mechanism determines the diameter of the Si nanowires. Different sources for the gold nanoparticles have been tested: the spontaneous dewetting of gold films, thermally annealed gold films, deposition of preformed gold nanoparticles, and the use of “liquid bright gold”, a material historically used for the gilding of porcelain and glass. The latter does not only form gold nanoparticles when deposited as a thin film and thermally annealed, but can also be patterned by using UV irradiation, providing access to laterally structured layers of silicon nanowires.

  15. Stratigraphy and mineralogy of a carbonate-hosted gold deposit: Kings Mountain gold mine, NC

    Energy Technology Data Exchange (ETDEWEB)

    Supplee, J.; Lapoint, D.; Feiss, P.G.

    1985-01-01

    The Kings Mountain Gold Mine, Cleveland Company, North Carolina, is unique in the Appalachians in that it is carbonate-hosted, with a distinctive ore mineralogy. The mine stratigraphy is upright, younging east to west. The basal unit is a volcanic to subvolcanic chlorite, feldspar, quartz-eye porphyry, cut by a silicic porphyry, interpreted as a shallow level intrusion. Above and gradational to the chloritic porphyry, unless separated by the intrusive silicic porphyry, is a sericitic, quartz-eye porphyry, probably a metatuff. A north-thinning, graphite schists is above the sericitic porphyry. Carbonates overlie the graphite schist except to the north where they are above the sericitic porphyry. The carbonates consist of basal and upper sequences separated by a sericite, quartz-eye schists (metatuff) which is capped by a chlorite-sericite-graphite schist. Mineralization occurs within each carbonate sequence. This is overlain by interbedded chlorite and graphite schists with two horizons of exhalative iron formation (I.F.). Above the I.F. is a thick sequence of sericitic chlorite schists (turbidites). The mineralized carbonates are pervasively silicified with a disseminated assemblage of pyrite, pyrrhotite, sphalerite, chalcopyrite, galena, gold, altaite (PbTe), tetrahedrite, and pyrargyrite in quartz and dolomite +/- fluorite gangue. We suggest that the mineralization is associated with hydrothermal activity during emplacement of the silicic porphyry and following carbonate diagenesis. Mineralization was syn- or post-depositional with respect to the I.F.

  16. Large clusters of gold deposits and large-scale metallogene-sis in the Jiaodong Peninsula, Eastern China

    Institute of Scientific and Technical Information of China (English)

    ZHAI; Mingguo

    2001-01-01

    , E, Xiao, Y. L. et al., Chronology of ultrahigh-pressure metamorphism in the Dabie mountain and Su-Lu terrane: I. Sm-Nd isotope system, Science in China (in Chinese), Ser. D, 1996, 26 (6): 597-609.[11]Ye, K., Guo, J. H., Zhai, M. G., The discovery and geological significance of coesite in the intercrystal of eclogite in Yangkou, Qingdao, Chinese Science Bulletin, 1996, 41(15): 1407-1408.[12]Liu, W. J., Zhai, M. G., Li, Y. G., Metamorphism of the high-pressure basic granulites in Laixi, eastern Shandong, China, Acta Petrologica Sinica (in Chinese), 1998, 14(4): 449-459.[13]Li, Y. G., Guo, J. H., Zhai, M. G., Geochemical differences of basement felsic gneisses in Shandong peninsula and its sig-nificance to the boundary between North China plate and Sulu UHP belt, Acta Petrologica Sinica (in Chinese), 1999, 15(4): 557-563.[14]Guo, W. K., Duan, C. J., The gold deposits in Linglong area, Zhaoyuan County, eastern Shandong Province, Geological Review (in Chinese), 1951, 16(1): 112-113.[15]Yu, H. M., Study on the isotope chronology of the rocks in the northwestern Jiaodong district, Shandong Province, Geolo-gy of Shandong (in Chinese), 1987, 3(1): 75-88.[16]Yao, F. L., Liu, L. D., Kong, Q. C. et al., The Lode Gold Deposits in Northwestern Jiaodong Peninsula (in Chinese), Changchun: Jilin Science and Technology Press, 1990, 1-234.[17]Li, Z. L., Yang, M. Z., The Geology-Geochemistry of Gold Deposits in Jiaodong Region (in Chinese), Tianjin: Tianjin Science and Technology Press, 1993, 1-300.[18]Wang, H. N., Wang, Y., The relationships of migmatite, granite and gold mineralization, Journal of Nanjing University (in Chinese), 1984, (supp.): 29-40.[19]Li, H. Q., Liu, J. Q., Wei L., The Isochronology of Inclusions of Hydrothermal Deposits and its Geological Application (in Chinese), Beijing: Geological Publishing House, 1993, 1-126.[20]Zhang, Z. H., Zhang, J. X., Ye, S. Z., The Isotopic Age of Gold Deposits in Jiaodong

  17. The Physico—Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit,Southwest Hunan,China

    Institute of Scientific and Technical Information of China (English)

    谷俐; 杨华; 等

    2002-01-01

    Experiments on water-rock interaction were carried out on wall-rock samples fromtheMobin gold deposit,Southwest Hunan,China ,with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution.Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit.Mobi-lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sul-phur ions at the concentration and composition of about[0.25M(NH4)2+1M NaCl].The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃.

  18. An Electrochemical and Raman Spectroelectrochemical Investigation of Underpotentially Deposited Silver on a Gold Substrate.

    Science.gov (United States)

    1986-07-30

    Raman Spectroelectrochemical Investigation of Underpotentially Deposited Silver on a Gold Substrate By Stanley Pons. J. Li, J. Liang DTIC S ELECTE APR 14...ACCCSSIONd 14U. 3. i4CCipIa.ti rs CATALOG. PiumnRi - 4. ITL (sa~utfie) . TYPE Of REPORT a PCI3ioo covEuiv Investigation of Underpotentially Deposited ...spectroelectrochemical data indicate that underpotentially * deposited silver adatoms on gold substrates are photolyzed to form silver meta clusters. *DD

  19. Gold nanoisland arrays by repeated deposition and post-deposition annealing for surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Sun, Xin; Li, Hao

    2013-09-06

    Gold nanoisland arrays with well controlled growth were achieved by repeated sputtering deposition and post-deposition annealing processes. When each deposition was set at 5 nm (nominal thickness based on gold mass), the single deposition and annealing process (single process) yielded gold nanoisland arrays with an average diameter of ~16 nm based on top view scanning electron microscopy (SEM). When the deposition and annealing process was repeated two more times (triple process), top view SEM showed the nanoisland arrays grew to ~38 nm in average diameter. The surface-enhanced Raman spectroscopy (SERS) measurement indicated that triple processed nanoisland arrays led to the highest SERS enhancement, suggesting the necessity of pursuing nanoislands with larger sizes. The gold nanoisland arrays after the triple process were further sputtered with a final layer of gold thin film at different nominal thicknesses. An optimal nominal thickness for SERS was determined experimentally at ~40 nm, as a result of the competition between the positive and negative effects of the final gold deposition. Last, the uniformity of the optimized SERS substrate was investigated on a 5 cm x 5 cm platform. SERS measurements demonstrated a relative standard deviation of ~7% in terms of spectral variation over the entire substrate, rendering the process in the present study a promising fabrication approach for large-scale production of SERS substrates.

  20. Constraints on mineralisation and hydrothermal alteration in the Nalunaq gold deposit, South Greenland

    DEFF Research Database (Denmark)

    Bell, Robin-Marie Fairbairn

    and hydrolysis reactions are important in locally precipitating gold, which may suggest an Au(HS)2- transport complex for gold. A c. 20 cm wide biotite-arsenopyrite alteration zone surrounds the gold-quartz veins locally, and denotes areas of high-gold grades. Implicit 3-Dimentional modelling has revealed......Summary: Nalunaq is located in South Greenland and is a small high gold-grade deposit, which for the majority of its operational life was Greenland's only metalliferous mine. Gold is hosted in narrow quartz veins which are cross-cut by late-stage faults. Gold-quartz veins are hosted by fine......-and - medium grained amphibolite of the Nanortalik Nappe. Detailed petrographic and geochronological studies have revealed a multi-stage hydrothermal alteration system, with alteration pre-and post-dating gold mineralisation. The hydrothermal alteration records a transition from upper-amphibolite facies...

  1. Existing forms of REE in gold-bearing pyrite of the Jinshan gold deposit,Jiangxi Province,China

    Institute of Scientific and Technical Information of China (English)

    毛光周; 华仁民; 高剑峰; 李伟强; 赵葵东; 龙光明; 陆慧娟

    2009-01-01

    Rare earth element(REE) is widely used in various fields of geology.Study of the existing forms of REE in geological objects is a necessity for us to solve geological problems related with REE.This paper tried to make it clear the existing forms of REE in gold-bearing pyrite in Jinshan gold deposit by stepwise dissolution test with ICP-MS analysis.Results showed that content of REE in fluid-inclusions of gold-bearing pyrite was very low,which only took about 0.07%-0.70% of the ΣREE,and that of pyrite phase ...

  2. Gold deposits in metamorphic belts: Overview of current understanding, outstanding problems, future research, and exploration significance

    Science.gov (United States)

    Groves, D.I.; Goldfarb, R.J.; Robert, F.; Hart, C.J.R.

    2003-01-01

    Metamorphic belts are complex regions where accretion or collision has added to, or thickened, continental crust. Gold-rich deposits can be formed at all stages of orogen evolution, so that evolving metamorphic belts contain diverse gold deposit types that may be juxtaposed or overprint each other. This partly explains the high level of controversy on the origin of some deposit types, particularly those formed or overprinted/remobilized during the major compressional orogeny that shaped the final geometry of the hosting metamorphic belts. These include gold-dominated orogenic and intrusion-related deposits, but also particularly controversial gold deposits with atypical metal associations. There are a number of outstanding problems for all types of gold deposits in metamorphc belts. These include the following: (1) definitive classifications, (2) unequivocal recognition of fluid and metal sources, (3) understanding of fluid migration and focusing at all scales, (4) resolution of the precise role of granitoid magmatism, (5) precise gold-depositional mechanisms, particularly those producing high gold grades, and (6) understanding of the release of CO2-rich fluids from subducting slabs and subcreted oceanic crust and granitoid magmas at different crustal levels. Research needs to be better coordinated and more integrated, such that detailed fluid-inclusion, trace-element, and isotopic studies of both gold deposits and potential source rocks, using cutting-edge technology, are embedded in a firm geological framework at terrane to deposit scales. Ultimately, four-dimensional models need to be developed, involving high-quality, three-dimensional geological data combined with integrated chemical and fluid-flow modeling, to understand the total history of the hydrothermal systems involved. Such research, particularly that which can predict superior targets visible in data sets available to exploration companies before discovery, has obvious spin-offs for global- to deposit

  3. Nitrogen isotope and content record of Mesozoic orogenic gold deposits surrounding the North China craton

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    As an effective tracer, nitrogen isotopes have been used to determine the source of ore materials in recent years. In this study, the nitrogen isotopes and contents were measured on K- feldspar and sericite of gold deposits and some related granitic intrusions in Jiaodong, Xiaoqinling-Xiong'ershan, west Qinling, the west part of North Qilian and the Zhangjiakou-Xuanhua district around the North China craton (NCC). Although the gold deposits around the NCC are hosted in Precambrian metamorphic rocks, Phanerozoic sedimentary rocks, mafic volcanic rocks or granite, comparison of which with the nitrogen contents and isotope data of previous studies on mantle-derived rocks, granites, metamorphic rocks and gold deposits indicates that those deposits are closely related to granitic rocks. In addition, mantle-derived materials may have been involved in the ore-forming processes to a certain degree. This conclusion is consistent with the result of previous hydrogen, oxygen and carbon isotopic studies of those gold deposits.

  4. Gold deposits of the Carolina Slate Belt, southeastern United States--Age and origin of the major gold producers

    Science.gov (United States)

    Foley, Nora K.; Ayuso, Robert A.

    2012-01-01

    Gold- and iron sulfide-bearing deposits of the southeastern United States have distinctive mineralogical and geochemical features that provide a basis for constructing models of ore genesis for exploration and assessment of gold resources. The largest (historic) deposits, in approximate million ounces of gold (Moz Au), include those in the Haile (~ 4.2 Moz Au), Ridgeway (~1.5 Moz Au), Brewer (~0.25 Moz Au), and Barite Hill (0.6 Moz Au) mines. Host rocks are Late Proterozoic to early Paleozoic (~553 million years old) metaigneous and metasedimentary rocks of the Carolina Slate Belt that share a geologic affinity with the classic Avalonian tectonic zone. The inferred syngenetic and epithermal-subvolcanic quartz-porphyry settings occur stratigraphically between sequences of metavolcanic rocks of the Persimmon Fork and Uwharrie Formations and overlying volcanic and epiclastic rocks of the Tillery and Richtex Formations (and regional equivalents). The Carolina Slate Belt is highly prospective for many types of gold ore hosted within quartz-sericite-pyrite altered volcanic rocks, juvenile metasedimentary rocks, and in associated shear zones. For example, sheared and deformed auriferous volcanogenic massive sulfide deposits at Barite Hill, South Carolina, and in the Gold Hill trend, North Carolina, are hosted primarily by laminated mudstone and felsic volcanic to volcaniclastic rocks. The high-sulfidation epithermal style of gold mineralization at Brewer and low-sulfidation gold ores of the Champion pit at Haile occur in breccias associated with subvolcanic quartz porphyry and within crystal-rich tuffs, ash flows, and subvolcanic rhyolite. The Ridgeway and Haile deposits are primarily epithermal replacements and feeder zones within (now) metamorphosed crystal-rich tuffs, volcaniclastic sediments, and siltstones originally deposited in a marine volcanic-arc basinal setting. Recent discoveries in the region include (1) extensions of known deposits, such as at Haile where

  5. Geology, Distribution and Classification of Gold Deposits in the Western Qinling Belt, Central China%西秦岭地区造山型与卡林型金矿床

    Institute of Scientific and Technical Information of China (English)

    毛景文

    2001-01-01

    Gold deposits of the western Qinling belt comprising Carlin-typeand orogenic type gold deposits. Carlin-like gold deposits are abundant (1) along a westward extension of the southern zone defined by a window of early Paleozoic clastic rocks extending into the basin to the west and (2) within the easternmost margin of the basinal rocks, south of the extension, and in adjacent cover rocks of the Yangtze craton. Triassic and Early Jurassic synkinematic granitoids are widespread across the central and southern zones, as well as in the Songpan-Ganzi basin and northern margin of the Yangtze craton.Orogenic lode gold deposits sited along brittle-ductile shear zones occur throughout the central zone within greenschist-facies, highly-deformed, Devonian and younger clastic rocks. Mainly coarse-grained gold, along with pyrite, pyrrhotite, arsenopyrite, and minor base metal sulfides, occur in networks of quartz veinlets, brecciated wallrock, and disseminated in altered wallrock. Isotopic dates suggest that the deposits formed during the Late Triassic to Middle Jurassic as the leading edge of the Yangtze craton was thrust beneath rocks of the western Qinling belt.Both Carlin-and orogenic types of gold deposits formed during extensional period of post-orogenesis, aged mainly from 210-180 Ma.%西秦岭金矿床分为卡林型和造山型两类。卡林型金矿床麇集于南秦岭和松潘—甘孜造山带的东北部。三叠纪和早侏罗世的同构造花岗闪长岩广泛分布于西秦岭中部和南部、松潘—甘孜盆地以及扬子克拉通边缘。造山型脉状金矿床主要分布于西秦岭造山带中的脆韧性剪切带内。大部分粗粒金主要赋存在网格状石英细脉和角砾状围岩中的黄铁矿、磁黄铁矿、毒砂和少量贱金属硫化物中和以分散状分布在蚀变围岩中。同位素资料表明晚三叠世-中侏罗世与扬子克拉通俯冲有关的作用控制了造山型金矿床的形成。

  6. Organic secondary ion mass spectrometry: sensitivity enhancement by gold deposition.

    Science.gov (United States)

    Delcorte, A; Médard, N; Bertrand, P

    2002-10-01

    Hydrocarbon oligomers, high-molecular-weight polymers, and polymer additives have been covered with 2-60 nmol of gold/cm2 in order to enhance the ionization efficiency for static secondary ion mass spectrometry (s-SIMS) measurements. Au-cationized molecules (up to -3,000 Da) and fragments (up to the trimer) are observed in the positive mass spectra of metallized polystyrene (PS) oligomer films. Beyond 3,000 Da, the entanglement of polymer chains prevents the ejection of intact molecules from a "thick" organic film. This mass limit can be overcome by embedding the polymer chains in a low-molecular-weight matix. The diffusion of organic molecules over the metal surfaces is also demonstrated for short PS oligomers. In the case of high-molecular-weight polymers (polyethylene, polypropylene, PS) and polymer additives (Irganox 1010, Irgafos 168), the metallization procedure induces a dramatic increase of the fingerprint fragment ion yields as well as the formation of new Aucationized species that can be used for chemical diagnostics. In comparison with the deposition of submonolayers of organic molecules on metallic surfaces, metal evaporation onto organic samples provides a comparable sensitivity enhancement. The distinct advantage of the metal evaporation procedure is that it can be used for any kind of organic sample, irrespective of thickness, opening new perspectives for "real world" sample analysis and chemical imaging by s-SIMS.

  7. Metallogenic epoch and genesis of the gold deposits in Jiaodong Peninsula, Eastern China: a regional review

    Institute of Scientific and Technical Information of China (English)

    YANG Liqiang; DENG Jun; GE Liangsheng; WANG Qingfei; ZHANG Jing; GAO Bangfei; JIANG Shaoqing; XU Hao

    2007-01-01

    Gold deposits are characterized by multi-sources, superimposition, large scale and temporal-spatial concentration in Jiaodong Peninsula, Eastern China. In this paper, we review the history and the development of the study on metallogenic chronology and genesis of gold deposits, summarize the main features of superimposed metallogenesis, provide evidence of the Mesozoic complex metallogenic system, and point out some problems for further research of Jiaodong gold deposit cluster from a regional view. Although gold deposits are different in genetic types, ore-forming materials and geological settings, our research indicates that the accumulation and emplacement of the ore-forming materials are temporally-spatially concentrated on a large scale, and the main metallogenic epoch of Jiaodong gold deposits was concentrated in Mesozoic. Metallogenic chronology and geological-geochemical data indicate that there are two periods of gold mineralizations occurred in 130-110 Ma and 90-80 Ma respectively in Jiaodong ore cluster. The gold deposit cluster results from the superimposition of the polygenetic mineralization, and further study is needed to investigate the formation and evolution of the Mesozoic complex metallogenic system.

  8. A Three—Stage Metallogenic Model for Gold Deposits in Metamorphosed Microclastic Rocks

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 程景平; 等

    1996-01-01

    Gld deposits occurring in metamorphosed microcelastic rocks are distributed extensively at home and abroad.Some deposits of this type are of superlarge tonnage.The formation of gold deposits in metamorphosed microclastic rocks involves three stages:the sedimentary stage,the regionally metamorphic stage,and the ore-forming stage.At the first stage,microclastic sedimentary source rocks were developed in a relatively semi-enclosed reducing sea basin and were enriched in carbon,sulfur and gold.At the second stage,the gold adsorbed on organic matter and clay minerals was relesed and poorly concentrated during the destruction of organic matter and the depletion of clay minerals by regional metamorphism with increase temperature and pressure.At the third stage,a tectono-hydrothermal event took place.As a result,gold was leached from metamorphosed microclastic rocks,transported to ore depositional locus and/or mixed with gold of other sources in the course of migration,and finally precipitared as ores.Gold deposits of this type were eventually formed at the third stage,and they also can be classified as the orogenic belt type and the activation zone type.The gold deposits occurring in metamorphosed microcalastic rocks are the products of reworking processes and the influence of magmatism should be taken into consideration in some cases.

  9. Genesis and organic geochemical characteristics of the carbonaceous rock stratabound gold deposits, South China

    Institute of Scientific and Technical Information of China (English)

    胡凯; 翟建平; 刘英俊; 王鹤年; 张景荣; 贾蓉芬

    2000-01-01

    The organic matter of three different chronological major carbonaceous rock gold-bearing formations of South China (Middle Proterozoic Shangqiaoshan group of northeastern Jiangxi, Lower Cambrian Shuikou group of northern Guangxi and Devonian Shetianqiao group of eastern Hunan) and related carbonaceous stratabound gold deposits such as Jinshan, Longshui and Shixia deposits, respectively, has been characterized by organic geochemical techniques. These organic geochemical results show that the average total organic carbon (TOC) content of the three chronological carbonaceous rock gold-bearing formations of South China ranges from 0.15% to 1.56%. The thermal maturity of the organic matter of host rocks in the three gold-bearing formations is high. The micro-component of the organic matter of the host rocks consists primarily of solid bitumen and graphite. The organic carbon and gold of the host rocks appear to syndeposit in situ during the formation of the gold-bearing formations. The organic carbon played

  10. Deep-Source Ore-Forming Materials and Prospecting of Gold Deposits in Eastern Hebei, China

    Institute of Scientific and Technical Information of China (English)

    王宝德; 牛树银; 孙爱群; 李红阳

    2003-01-01

    Eastern Hebei Province is one of the important gold mineralization areas in North China, and detailed investigations have been made in this area. Different mineralization models and different ore-forming sources have been proposed for the gold deposits in this area. As more detailed work was made and more information has been accumulated, it is necessary to make a new investigation on gold metallogenesis and its source. This paper presents the data about 13 gold deposits (occurrences). It is concluded that the element gold came from the deep mantle.Different models of metallogenesis substantially describe such processes that ore-forming fluids were involved in metallogenesis in different favorable loci. Gold ore prospecting should be focused on fluid channel ways and favorable structures.

  11. Carlin-Type Gold Deposits in Qinling and Some Related Problems

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The sediment-hosted disseminated gold deposits in the Oinling region are of sedimentation-slight-metamorphic origin superimposed by hydrothermal reworking at moderate-low temperatures and are well comparable with the typical Carlin gold deposits in the United States.In view of the confusing concept concerning the “sediment-hosted”and “Carlin-type” gold deposits,the authors propose that the term“sediment-hosted gold deposit”should be used in a broad sense which encompasses at least the four subtypes,i.e.,the Carlin type,the metamorphic fine clastic type,the hydrothermal sedimentary type and the vein type.In oter words,the “Carlin-type”should not be used as a synonym for “sediment-hosted”but is recommended as a subtype under the general category of “sediment-hosted gold deposits”

  12. Towards an electroless deposition of gold on metallic substrates using ionic liquids as electrolytes

    OpenAIRE

    Sá, A. I. Correia de; Quaresma, S.; Eugénio, S.; Rangel, C. M.; Vilar, Rui

    2010-01-01

    Recent research has suggested a number of applications for gold in fuel cells and related hydrogen fuel processing, which include coatings for light weight corrosion resistance bipolar plates and the incorporation of gold as catalyst to provide improvements in electrode conductivity, among others. This paper reports on the electroless deposition of gold on copper substrates from a HAuCl4.3H2O solution in 1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), in normal atmospheric conditions. Th...

  13. Highly conductive and pure gold nanostructures grown by electron beam induced deposition

    Science.gov (United States)

    Shawrav, Mostafa M.; Taus, Philipp; Wanzenboeck, Heinz D.; Schinnerl, M.; Stöger-Pollach, M.; Schwarz, S.; Steiger-Thirsfeld, A.; Bertagnolli, Emmerich

    2016-09-01

    This work introduces an additive direct-write nanofabrication technique for producing extremely conductive gold nanostructures from a commercial metalorganic precursor. Gold content of 91 atomic % (at. %) was achieved by using water as an oxidative enhancer during direct-write deposition. A model was developed based on the deposition rate and the chemical composition, and it explains the surface processes that lead to the increases in gold purity and deposition yield. Co-injection of an oxidative enhancer enabled Focused Electron Beam Induced Deposition (FEBID)—a maskless, resistless deposition method for three dimensional (3D) nanostructures—to directly yield pure gold in a single process step, without post-deposition purification. Gold nanowires displayed resistivity down to 8.8 μΩ cm. This is the highest conductivity achieved so far from FEBID and it opens the possibility of applications in nanoelectronics, such as direct-write contacts to nanomaterials. The increased gold deposition yield and the ultralow carbon level will facilitate future applications such as the fabrication of 3D nanostructures in nanoplasmonics and biomolecule immobilization.

  14. Genesis and organic geochemical characteristics of the carbonaceous rock stratabound gold deposits, South China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The organic matter of three different chronological major carbonaceous rock gold-bearing formations of South China (Middle Proterozoic Shangqiaoshan group of northeastern Jiangxi, Lower Cambrian Shuikou group of northern Guangxi and Devonian Shetianqiao group of eastern Hunan) and related carbonaceous stratabound gold deposits such as Jinshan, Longshui and Shixia deposits, respectively, has been characterized by organic geochemical techniques. These organic geochemical results show that the average total organic carbon (TOC) content of the three chronological carbonaceous rock gold-bearing formations of South China ranges from 0.15% to 1.56%. The thermal maturity of the organic matter of host rocks in the three gold-bearing formations is high. The micro-component of the organic matter of the host rocks consists primarily of solid bitumen and graphite. The organic carbon and gold of the host rocks appear to syndeposit in situ during the formation of the gold-bearing formations. The organic carbon played a certain role in controlling the geochemical environment of the gold-bearing formations. The metallogenetic mechanism of the carbonaceous rock stratabound gold deposits of South China is closely associated in genesis with the sedimentation, diagenesis and thermal evolution history of the organic matter of host rocks in the gold-bearing formations.

  15. GEOLOGY OF THE FLORENCIA GOLD – TELLURIDE DEPOSIT (CAMAGÜEY, CUBA AND SOME METALLURGICAL CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    López K Jesús M.

    2006-12-01

    Full Text Available This paper describes the results from a study of the Florencia gold-telluride deposit in Central Cuba, including mineralogical, petrographical, microprobe and chemical analysis. Valuable information is provided for the exploration, mining and processing of gold ores from other nearby deposits with similar characteristics. Results highlight changes in the mineralogical composition of the ores between the north and south sectors of the deposit, as reflected in metallurgical concentrates after beneficiation and flotation of samples from these sectors.
    It is shown that gold deposits of the Cretaceous Volcanic Arc of Cuba largely consist of native gold, telluride and pyrite, where arsenopyrite is almost absent. Traces of lead, zinc and cadmium are present in the periphery of the main ore zones.

  16. Rare Earth Elements Geochemistry of Dongtian Gold Deposit in Western Guangdong

    Institute of Scientific and Technical Information of China (English)

    曹建劲

    2003-01-01

    Yunkai uplifted area is one of the important metallogenic areas in Guangdong and Guangxi Provinces, in which many gold, silver, tungsten, tin, lead, zinc, molybdenum, and iron deposits were found. Dongtian gold deposit in the middle of Yunkai uplifted area, western Guangdong Province, is chosen as an example of those deposits. Comparative studies on the chondrite-normalized REE patterns and ΣREE, LREE/HREE, δEu, δCe, NLa/Yb, and NLa/Sm of auriferous quartz veins, altered gneiss-type gold ores, Caledonian gneissic biotite granite, and Late Yanshanian granite porphyry were made. The results indicate that the source of the metallogenic materials of the auriferous quartz veins and the altered gneiss-type gold ores are the same, and both of them come from the gneissic biotite granite. Metallogenic epoch of the deposit is estimated to be Caledonian period.

  17. Obliquely Deposited Gold Nanohelices on Lithography-Free Prepared Nanoseeded Surfaces

    Science.gov (United States)

    Jen, Yi-Jun; Liu, Wei-Chih; Hsiao, Chih-Yung; Lin, Po-Cheng; Yu, Chia-Liang; Chan, Teh-Li

    2017-08-01

    A substrate surface on which gold particles are distributed is prepared by annealing an ultra-thin gold film to enable glancing angle deposition. By cooling the substrate and controlling its spin rate, two spiral-like and one screw-like gold nanohelix arrays are grown upon the seeded surfaces. The mean helix radius and pitch length are reduced to 17 and 55 nm, respectively. The g-factor of the three nanohelix arrays is measured here and associated circular dichroism peak blue shifts occur as the gold helices shrink.

  18. Self-assembling Process of Alkanethiol Monolayers on Gold Surface via Underpotential Deposition

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    It was demonstrated feasible that underpotential deposition(UPD) of copper on a monolayer-modified gold substrate can be used to determine the gold electrode area. The deposition and stripping of a Cu adlayer can take place reversibly and stably at a bared or a self-assembled monolayer modified gold electrode. The growth kinetics of decanethiol/Au was also investigated via Cu UPD. The difference between the assembling kinetics determined by UPD and that by quartz crystal microbalance measurements reveals the configuration transmutation of the assembled molecules from a disordered arrangement to an ordered arrangement during the self-assembling processes.

  19. Deposition of gold and silver on porous silicon and inside the pores

    Energy Technology Data Exchange (ETDEWEB)

    Nativ-Roth, Einat [Ilse Katz Institute of Nanoscale Science and Technology, Ben-Gurion University of the Negev, Be' er Sheva 84105 (Israel); Rechav, Katya [Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100 (Israel); Porat, Ze' ev, E-mail: poratze@post.bgu.ac.il [Division of Chemistry, Nuclear Research Center–Negev, Be' er Sheva 84190 (Israel); Institutes of Applied research, Ben-Gurion University of the Negev, Be' er Sheva 84105 (Israel)

    2016-03-31

    Silver and gold were spontaneously deposited on porous silicon (PSi) by immersion-plating. Each metal formed crystallites of typical shapes on top of the PSi layer. Deposition of these metals inside the pores could be achieved by performing the immersion-plating in an ultrasonic bath. Top view and cross-section scanning electron microscope images show slight penetration of silver into the pores but massive filling of gold, to depth of several hundreds of nanometers. - Highlights: • Spontaneous reduction of Ag and Au ions occurs on porous silicon (immersion plating). • Such deposition inside the pores is prevented by entrapped hydrogen bubbles. • Immersion plating under sonication releases the gas and enhances ions diffusion. • Silver and gold were deposited within the pores by ultrasonic-aided deposition.

  20. Geological structure, composition of ores and age of the Bamsk gold deposit, Amur region, Russia

    Institute of Scientific and Technical Information of China (English)

    Vitaly A. Stepanov

    2004-01-01

    The Bamsk gold-ore deposit is located in the Amur region, the Far East of Russia. It is confined to the Early Cretaceous volcanic-plutonic uplift of central type, located in the Stanov folded-clumpy Pre-Cambrian system. The deposit is presented by a series of gold-bearing quartz and carbonate-quartz vein-stringer zones. They are confined to the super-intrusive zone of the Nevachansk subvolcanic intrusion of sienite-porphyric composition. The mineralization is being controlled by zone of fractures developed in the autochthone ofthe Bamsk fault. Quartz, carbonates and sericite prevail in the composition of ores. The quantity of ore minerals doesn't exceed 1%~5%. Pyrite, chalcopyrite, galena and native gold are widely spread. Sheelite, gold and silver tellurides, sulphobismuthites, acanthite, sphalerite and cinnabar are less developed. Four stages of mineralization have been distinguished. Gold-sulphide-sulphosalt ore with tellurides of gold and silver is productive for gold. The following set of elements is typomorphic for the ores of the deposit: Au, Ag, Cu, Bi,Mo, Pb and Sb (W1, Pb1, Mo) -Cu- (Ag, Bi, Sb, Mn, W1, Pb2) form the vertical series of zoning. Rocks, enclosing the mineralization are exposed to the processes of listvenitization-beresitization. The processes of gumbeization and argillization are less manifested. The age of the gold mineralization, determined by Rb-Sr method on ore-accompanying minerals, is 130.6 Ma.

  1. Geological characteristics of the Pulai alluvial gold deposit, South Kelantan, Malaysia

    Science.gov (United States)

    Batchelor, D. A.-F.

    The Pulai fluviatile gold placer deposit stretches along 17 km of the upper reaches of S. Galas. Malaysia Mining Corporation had proved-up sizeable reserves following drilling and bulk testing during 1979-1983. The valley alluvium ranges up to 1200 m wide and averages 6.2 m in thickness. The basal gold-bearing Kaksa comprises bimodal channel lag pebble-gravels with the gold especially concentrated immediately above bedrock and in potholes. The detrital gold is medium to very coarse sand size, moderately sorted, and occurs as fine grains, scaly flakes and platy nuggets. Concentration of gold was especially favoured in two depositional environments. In the slope interruption zones at the confluence of the Galas and Tuang streams, coarse platy gold was deposited while the finer gold was able to be entrapped further downstream above irregular limestone bedrock surfaces. The gold is of relatively high fineness (950-982), and is probably related genetically to acid intrusions. Important primary sources lie near the Kelantan-Pahang border, 3-5 km SE of Pulai village, while small granite stocks occurring 3 km west of Pulai are an additional likely source.

  2. Sediment-hosted gold deposits of the world: database and grade and tonnage models

    Science.gov (United States)

    Berger, Vladimir I.; Mosier, Dan L.; Bliss, James D.; Moring, Barry C.

    2014-01-01

    All sediment-hosted gold deposits (as a single population) share one characteristic—they all have disseminated micron-sized invisible gold in sedimentary rocks. Sediment-hosted gold deposits are recognized in the Great Basin province of the western United States and in China along with a few recognized deposits in Indonesia, Iran, and Malaysia. Three new grade and tonnage models for sediment-hosted gold deposits are presented in this paper: (1) a general sediment-hosted gold type model, (2) a Carlin subtype model, and (3) a Chinese subtype model. These models are based on grade and tonnage data from a database compilation of 118 sediment-hosted gold deposits including a total of 123 global deposits. The new general grade and tonnage model for sediment-hosted gold deposits (n=118) has a median tonnage of 5.7 million metric tonnes (Mt) and a gold grade of 2.9 grams per tonne (g/t). This new grade and tonnage model is remarkable in that the estimated parameters of the resulting grade and tonnage distributions are comparable to the previous model of Mosier and others (1992). A notable change is in the reporting of silver in more than 10 percent of deposits; moreover, the previous model had not considered deposits in China. From this general grade and tonnage model, two significantly different subtypes of sediment-hosted gold deposits are differentiated: Carlin and Chinese. The Carlin subtype includes 88 deposits in the western United States, Indonesia, Iran, and Malaysia, with median tonnage and grade of 7.1 Mt and 2.0 g/t Au, respectively. The silver grade is 0.78 g/t Ag for the 10th percentile of deposits. The Chinese subtype represents 30 deposits in China, with a median tonnage of 3.9 Mt and medium grade of 4.6 g/t Au. Important differences are recognized in the mineralogy and alteration of the two sediment-hosted gold subtypes such as: increased sulfide minerals in the Chinese subtype and decalcification alteration dominant in the Carlin type. We therefore

  3. Gold and trace element zonation in pyrite using a laser imaging technique: Implications for the timing of gold in orogenic and carlin-style sediment-hosted deposits

    Science.gov (United States)

    Large, R.R.; Danyushevsky, L.; Hollit, C.; Maslennikov, V.; Meffre, S.; Gilbert, S.; Bull, S.; Scott, R.; Emsbo, P.; Thomas, H.; Singh, B.; Foster, J.

    2009-01-01

    Laser ablation ICP-MS imaging of gold and other trace elements in pyrite from four different sediment- hosted gold-arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit: an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements, in particular, As, Ni, Pb, Zn, Ag, Mo, Te, V, and Se; and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and/or hydrothermal pyrite or as narrow gold- arsenic rims on the outermost parts of the overgrowth hydrothermal pyrite. Compared to the diagenetic pyrites, the hydrothermal pyrites are commonly depleted in Ni, V, Zn, Pb, and Ag with cyclic zones of Co, Ni, and As concentration. The outermost hydrothermal pyrite rims are either As-Au rich, as in moderate- to high- grade deposits such as Carlin and Bendigo, or Co-Ni rich and As-Au poor as in moderate- to low-grade deposits such as Sukhoi Log and Spanish Mountain. The early enrichment of gold in arsenic-bearing syngenetic to diagenetic pyrite, within black shale facies of sedimentary basins, is proposed as a critical requirement for the later development of Carlin-style and orogenic gold deposits in sedimentary environments. The best grade sediment-hosted deposits appear to have the gold climax event, toward the final stages of deformation-related hydrothermal pyrite growth and fluid flow. ?? 2009 Society of Economic Geologists, Inc.

  4. Isotope Geochemistry of Gold Ore Deposits in the Gezhen Shear Zone, Qiongxi, Hainan Island

    Institute of Scientific and Technical Information of China (English)

    夏勇

    2004-01-01

    Gold deposits hosted in the Gezhen shear zone at Qingxi, Hainan Island occur in the Precambrian metamorphic rock series and are regionally developed in the N-E direction along the tectonic zone. From northeast to southwest are distributed the Tuwaishan-Baoban gold mining district, the Erjia gold mining district and the Bumo gold mining district, making up the most industrially important gold metallogenesis zone on the Hainan Island. Isotope geochemical studies of the typical gold deposits in this metallogenesis zone indicate that their ore-forming materials stemmed largely from the Baoban Group migmatite series, though the involvement of some plutonic materials could not be ruled out. The ore fluids are the mixture of migmatitized hydrothermal solutions and meteoric waters in addition to the involvement of local magmatic hydrothermal solutions. The superimposition of plutonic materials and magmatic hydrothermal solutions is controlled by the deformation environment of the shear zone and later magmatic activities. Obvious variations are noticed in isotopic composition in the region studied, probably related to tectonic deformation, metamorphism and other evolutionary characteristics. This study is of great significance in understanding the relationship between the shear zone and gold metallogenesis, the rules of gold metallogenesis and gold ore prognosis.

  5. Witwatersrand gold deposits formed by volcanic rain, anoxic rivers and Archaean life

    Science.gov (United States)

    Heinrich, Christoph A.

    2015-03-01

    The Witwatersrand Basin in South Africa is one of the best-preserved records of fluvial sedimentation on an Archaean continent. The basin hosts the worlds biggest gold resource in thin pebble beds, but the process for gold enrichment is debated. Mechanical accumulation of gold particles from flowing river water is the prevailing hypothesis, yet there is evidence for hydrothermal mobilization of gold by fluids invading the metasedimentary rocks after their burial. Earth's atmosphere three billion years ago was oxygen free, but already sustained some of the oldest microbial life on land. Here I use thermodynamic modelling and mass-balance calculations to show that these conditions could have led to the chemical transport and precipitation of gold in anoxic surface waters, reconciling the evidence for fluvial deposition with evidence for hydrothermal-like chemical reactions. I suggest that the release of sulphurous gases from large volcanic eruptions created acid rain that enabled the dissolution and transport of gold in surface waters as sulphur complexes. Precipitation of the richest gold deposits could have been triggered by chemical reduction of the dissolved gold onto organic material in shallow lakes and pools. I conclude that the Witwatersrand gold could have formed only during the Archaean, after the emergence of continental life but before the rise of oxygen in the Earth's atmosphere.

  6. Gold deposit styles and placer gold characterisation in northern and east-central Madagascar

    Science.gov (United States)

    Pitfield, Peter E. J; Styles, Michael T.; Taylor, Cliff D.; Key, Roger M.; Bauer,; Ralison, A

    2009-01-01

    Microchemical characterisation of bedrock and placer gold grains from six gold districts within the Archaean domains and intervening Neoproterozoic Anaboriana-Manampotsy belt of northern and east-central Madagascar show few opaque inclusions (e.g pyrrhotite, Bi tellurides) but wide range of Ag contents (40wt%). Some districts exhibit multiple source populations of grains. The ‘greenstone belt’ terranes have an orogenic gold signature locally with an intrusion-related to epithermal overprint. Proterozoic metasediments with felsic to ultramafic bodies yield dominantly intrusion-related gold. A high proportion of secondary gold (<0.5wt% Ag) is related to recycling of paleoplacers and erosion of post-Gondwana planation surfaces and indicates that some mesothermal gold systems were already partially to wholly removed by erosion by the PermoTriassic.

  7. Analysis of Ore-controlling Structure in the Qifengcha-Detiangou Gold Deposit, Huairou County, Beijing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Qifengcha-Detiangou gold deposit is a medium-sized deposit recently found in Huairou County, Beijing. It belongs to the altered mylonite type with superimposed quartz vein type and is related to the early Yanshanian magmatic activity. Characterized by multiperiodic activity, the NE-trending Qifengcha fault is a regional ore-controlling structure in the area, and gold mineralization develops only in its southeastern part. Meanwhile, gold mineralization is controlled by the Yunmengshan metamorphic core complex. The nearly N-S- and E-W-trending low-angle detachment faults, reformed by the Qifengcha fault in the northwestern part of the core complex, are the main ore-bearing faults. All discovered gold deposits are located within an area 1.5(4.0 km away from the boundary of the upwelling centre. The N-S- (NNE-) and E-W-trending ore-bearing faults are ductile-brittle structural zones developing in shallow positions and subjected mainly to compressive deformation. The structural ore-controlling effects are as follows. (1) The attitude, shape, and distribution of gold orebodies are controlled by faults. (2) There is a negative correlation between the gold abundance and the magnetic anisotropy (P) of the altered mylonite samples from the deposit, which shows that the gold mineralization is later than the structural deformation. (3) Quartz vein type mineralization is superimposed on altered mylonite type mineralization. (4) In mineralized mylonite, the stronger the ductile shear deformation, the easier the late-stage gold mineralization to occur and the higher the gold abundance. The richest gold mineralization occurs only around the centre of the fault subjected to the strongest deformation.

  8. How Gold Deposition Affects Anatase Performance in the Photo-catalytic Oxidation of Cyclohexane

    NARCIS (Netherlands)

    Carneiro, Joana T.; Yang, Chieh-Chao; Moma, John A.; Moulijn, Jacob A.; Mul, Guido

    2009-01-01

    Gold deposition on Hombikat UV100 was found to negatively affect the activity of this Anatase catalyst in selective photo-oxidation of cyclohexane. By ammonia TPD and DRIFT spectroscopy it was determined that the Au deposition procedure leads to a significant decrease in OH-group density (mol m−2 BE

  9. Significance of native arsenic in the Baogutu gold deposit, western Junggar, Xinjiang, NW China

    Institute of Scientific and Technical Information of China (English)

    AN Fang; ZHU YongFeng

    2009-01-01

    Native arsenic together with comb quartz and stibnite is found in the Baogutu gold deposit, western Junggar (Xinjiang), NW China. It is anhedral with various grain size ( con-centration of hydrothermal fluid decrease obviously, whereas the As concentration increases. Coexis-tence with native arsenic of electrum and its contents of 0.5 wt%-1.3 wt% As suggest that As is im-portant to transport Au when S concentration decrease in hydrothermal fluid. Crystallization of native arsenic induced the deposition of electrum and consequently the formation of the Baogutu gold deposit.

  10. Sulphur Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Zhang Hongying; Liu Xiang

    2001-01-01

    Shibaqinghao gold deposit is situated in the western part of the northern margin of the North China Craton. It is controlled by an E - W trending tectonic zone that is located in the middle unit of Dongwufenzi group which consists of a sequence of greenschist - facies metamorphic rocks in an Archean greenstone belt.In Shibaqinghao gold deposit there are two types of gold ore, a mylonite ore and a quartz vein ore. Mylonite ore bodies were formed during ductile shearing stage in the Early Proterozoic, whereas quartz vein ore bodies might have been formed in the Mesozoic time.Pyrite accompanied with native gold in the mylonite ore has sulpfur of which δ34S values range from - 5.8 to + 0.8 per mil, similar to the values of mantle- derived sulphur. These data suggest that gold in the mylonite ore be derived from the country rocks which originated directly in the upper mantle.Pyrite in quartz vein ore has the δ34 S values between + 3.0 and + 11.0 per mil, similar to the values of some granitic rocks. These facts indicate that the gold in the quartz vein ore is related to some granitic magma generated in the crust.This study revealed that two different mineralization occurred at different geological times and in different environments but in the same place, resuling in the Shibaqinghao gold deposit.

  11. Gold deposits in the western sector of the Central Spanish System; Depositos auriferos del sector occidental del sistema Central espanol

    Energy Technology Data Exchange (ETDEWEB)

    Barrios, S.; Florido, P.; Reguilon, R.

    2010-07-01

    The gold deposits in the western sector of the Central Spanish System can be grouped in: (1) gold quartz veins type (El Chivote, La Pedrera), (2) paleoplacers: gold nuggets in tertiary alluvial deposits (Las Cavenes, Sierro de Coria), (3) quaternary placers (Rio Erjas), (4) gold nuggets in a regolith developed on the Schist and Graywacke Complex (CEG) (Casillas de Coria). The morphological study of gold nuggets will provide physical, chemical, bacteriological and climatic characteristics. Mining works are located on these deposits from roman time to the present day. (Author)

  12. Crude oil as carrier of gold: petrological and geochemical evidence from Lannigou gold deposit in southwestern Guizhou, China

    Institute of Scientific and Technical Information of China (English)

    庄汉平; 卢家烂; 傅家谟; 任炽刚; 邹德刚

    1999-01-01

    Organic matter is related closely to mineralization of Lannigou gold deposit in southwestern Guizhou, China, Regionally, the distribution of organic carbon agrees well with that of faults within which gold deposits are hosted. Studies on organic petrology show that pyrobiturnen, which is related most closely to mineralization, adheres to quartz vein or fills quartz veinlet. Proton-induced X-ray emission (PIXE) analysis shows an evident abundance of Au in pyrobitumen. Pyrobitumen paragenetically associates with pyrite and arsenopyrite which are the main carrier minerals of Au. The thermal simulation experiment indicates that about 99% of Au will be concentrated in oil phase in the coexisting system of oil and brine and rock. The role of crude oil in ore-forming process is: as carrier of Au, crude oil moves upwards, and undergoes thermal decomposition and thermochemical reduction when it encounters the oxidizing fluid within the Trassic turbidity; Au is thus released from crude oil, reduced and precipitat

  13. In Situ Synthesis and Deposition of Gold Nanoparticles with Different Morphologies on Glass and ITO Substrate by Ultrasonic Spray Pyrolysis

    OpenAIRE

    María de la Garza; Israel López; Idalia Gómez

    2013-01-01

    Gold nanoparticles were synthesized and deposited in situ by ultrasonic spray pyrolysis on glass and indium tin oxide (ITO) substrates. This technique led to the formation of gold nanoparticles with different morphologies without the use of any capping agent. The gold nanoparticles deposited on glass substrate were obtained as nanospheres with an average particle size of 30 nm with some agglomerates; however, the nanoparticles deposited on ITO substrate were obtained with different morphologi...

  14. Tellurium-Gold Mineralization Related to Cryptoexplosive Breccias within Volcanic Pipe in Zhuojiazhuang Gold Deposit,Shandong Province, China

    Institute of Scientific and Technical Information of China (English)

    Zeng Qingdong; Liu Tiebing; Shen Yuanchao; Li Guangming

    2002-01-01

    Zhuojiazhuang gold deposit (ZGD) is the most enriched breccia pipe type gold deposit in East China, resulted from cryptoexplosion related to alkalinic magmatism and orebearing fluid filling. The ZGD is a small-sized mine with over 5 tons of gold reserves and grade of 156g/t in average and the highest 2 728 g/t as known. In addition, tellurium and silver are also valuable.The mineralized breccia pipe is cylinder-like in shape with 15 m long and 10 m wide and controlled by intersection ofNW and EW trend faults. Mining level has reached 170 m below the surface, but the whole pipe mineralization is still stable. Mineralization commonly occurs within the cements of breccias. Gold ores consist of hydrothermal breccia ore, shatteredbreccia ore and cataclastic ore. From the center of the ore body outwards, there is the transition from hydrothermal breccia toshattered breccia and then to cataclastic ores. According to composition and amount of the cements, the hydrothermal brecciaores can further be divided into three subtypes: sulfides cemented, hydrothermal mineral cemented and magma cemented.The content of gold is closely related to the types of the cements. The grade of the sulfide cemented breccia is the highestone, usually more than 1 000 g/t, and the known maximum grade is 2 728 g/t. The composition of the shattered breccia ismainly dioritic porphyrite and cemented by hydrothermal minerals, the grade ranges from ten to several tens g/t. The catsclastic ores are mainly composed of dioritic porphyrite, syenitic porphyry, as well as carbonate with mineralized veins, and the grade is only 35 g/t.Major ore minerals consist of pyrite, native tellurium, sphalerite, with minor calaverite, galena and altaite. Gangueminerals are composed of microcrystalline quartz, decktite and fluorite, with minor sericite and calcite. Brecciated and disseminited structures are main structures of ores. Four ore-forming stages are defined: microcrystalline quartz-pyrite stage

  15. Combined optical second harmonic generation/quartz crystal microbalance study of underpotential deposition processes: copper electrodeposition on polycrystalline gold.

    Science.gov (United States)

    Lakkaraju, S; Bennahmias, M J; Borges, G L; Gordon Ii, J G; Lazaga, M; Stone, B M; Ashley, K

    1990-11-20

    Optical second harmonic generation and quartz crystal microbalance techniques are used as in situ probes of copper underpotential deposition on polycrystalline gold surfaces in sulfuric acid electrolyte. The second harmonic signal from a polished bulk gold substrate is observed to decrease by >60% as a result of copper underpotential deposition on gold. Also, the mass of an underpotentially deposited copper adlayer is monitored in situ by an oscillating quartz crystal microbalance, yielding an estimated coverage of ~8.0 x 10(-10) mol cm(-2) and an electrosorption valency of 1.5 for a copper adlayer on the surface of vapor-deposited polycrystalline gold.

  16. Remnant colloform pyrite at the haile gold deposit, South Carolina: A textural key to genesis

    Science.gov (United States)

    Foley, N.; Ayuso, R.A.; Seal, R.R.

    2001-01-01

    Auriferous iron sulfide-bearing deposits of the Carolina slate belt have distinctive mineralogical and textural features-traits that provide a basis to construct models of ore deposition. Our identification of paragenetically early types of pyrite, especially remnant colloform, crustiform, and layered growth textures of pyrite containing electrum and pyrrhotite, establishes unequivocally that gold mineralization was coeval with deposition of host rocks and not solely related to Paleozoic tectonic events. Ore horizons at the Haile deposit, South Carolina, contain many remnants of early pyrite: (1) fine-grained cubic pyrite disseminated along bedding; (2) fine- grained spongy, rounded masses of pyrite that may envelop or drape over pyrite cubes; (3) fragments of botryoidally and crustiform layered pyrite, and (4) pyritic infilling of vesicles and pumice. Detailed mineral chemistry by petrography, microprobe, SEM, and EDS analysis of replaced pumice and colloform structures containing both arsenic compositional banding and electrum points to coeval deposition of gold and the volcanic host rocks and, thus, confirms a syngenetic origin for the gold deposits. Early pyrite textures are present in other major deposits of the Carolina slate belt, such as Ridgeway and Barite Hill, and these provide strong evidence for models whereby the sulfide ores formed prior to tectonism. The role of Paleozoic metamorphism was to remobilize and concentrate gold and other minerals in structurally prepared sites. Recognizing the significance of paragenetically early pyrite and gold textures can play an important role in distinguishing sulfide ores that form in volcanic and sedimentary environments from those formed solely by metamorphic processes. Exploration strategies applied to the Carolina slate belt and correlative rocks in the eastern United States in the Avalonian basement will benefit from using syngenetic models for gold mineralization.

  17. Gravity worms in the prospecting of epigenetic gold deposits: Example from the Northern Fennoscandian Shield

    Science.gov (United States)

    Lahti, Ilkka; Nykänen, Vesa; Niiranen, Tero

    2010-05-01

    Mapping of mineralized geologic structures using geophysical potential field datasets has become an essential part of present-day exploration projects. Various geophysical processing and semiautomatic interpretation techniques have provided new tools into the field of conventional exploration process. Such is the multiscale edge detection or "worming-technique" introduced by Hornby et al., (1999). Worms are representations of the maxima of potential field horizontal gradients. They are calculated at different upward continuation levels providing an alternative view into potential field anomalies and geometry of the anomaly sources. In this work we use the worming-technique on the regional gravity dataset collected by the Geological Survey of Finland during the last four decades in the northern Finland. The dataset consists of more than 19 000 ground gravity observations covering an area of about 15000 km2 with an average site separation of 0.5 - 1 km. The study area covers the central part of the 2.4-2.0 Ga Central Lapland Greenstone belt (CLGB) which is one of the largest Proterozoic greenstone terrains in the world. The CLGB hosts numerous gold occurrences of varying type and size. The majority of the gold occurrences fall into the orogenic gold category but also Iron Oxide-Copper-Gold (IOCG) and paleoplacer types are known within the region (e.g. Eilu et al., 2007). Currently the largest known deposit in the area is the Suurikuusikko orogenic gold deposit with current resources exceeding 5 million ounces Au. The largest known gold resources in IOCG type deposit is in the Hannukainen deposit with ca. 200 000 ounces of gold. All the known orogenic gold and IOCG deposits in the CLGB show intimate spatial correlation to shear zones of varying scale. Processed gravity worms display striking spatial correlation with the known orogenic gold and IOCG deposits. In some cases the gold hosting shear zones are outlined by gravity worms either completely (Sirkka shear zone

  18. Gold-silver-tellurium mineral assemblages in different ore styles of the Southern Urals VHMS deposits

    Science.gov (United States)

    Maslennikov, V. V.; Zaykov, V. V.; Maslennikova, S. P.; Tesalina, S. G.; Herrington, R. J.; Buschmann, B.; Becker, K.; Petersen, S.; Orgeval, J. J.; Leistel, M.

    2003-04-01

    VMS deposits of the South Urals generally show a continuum in degradation and reworking ranging from pristine steep-sided hydrothermal sulphide mounds to deposits dominated by layered strata of clastic sulphides. Four different deposits with varying degrees of degradation in order of increased reworking: (Yaman-Kasy longrightarrow Molodezhnoe longrightarrow Alexandrinskoe longrightarrow Balta-Tau) have been ranged. The influence of sulphide mound destruction and of sea-floor alteration on mineral assemblages was investigated In the pristine Yaman-Kasy sulphide mound gold and silver occur as altaite+tellurium+hessite-stuetzite+sylvanite and later galena+native gold+pyrite assemblages in chalcopyrite+isocubanite-rich linings of former chimney conduits. Chalcopyrite-dominated conduit fragments in clastic ore facies contain native tellurium+gold intergrowths. In the weakly reworked Molodezhnoe deposit gold-silver assemblages only occur in sea-floor altered clastic sulphides on the slope of massive sulphide mounds in bornite- and tennantite-rich ores in association with Cu-Ag sulfides such as jalpaite, mckinstryite, and stromeyerite and rare Au-Ag-tellurides (petzite). The Alexandrinskoe deposit is dominated by clastic ores and here native gold and rare hessite occur together with galena in tennantite-sphalerite-dominated veins of the footwall as well as in drusy sphalerite forming conduits of vent chimneys. An assemblage of electrum+galena+tennantite was observed in secondary chalcopyrite in the outer walls of chimneys. Native gold+stromeyerite are common in bornite-rich clastic sulphides while an assemblage of Ag-sulphosalts+electrum is common in barite-rich ores. In the reworked Balta-Tau deposit Ag-sulphosalts+electrum-kustelite occur often together with tennantite+galena+barite banded ores. Gold-silver-telluride mineralisation in these VMS deposits changes with degree of reworking from Au-tellurides, and native gold+galena+pyrite in pristine sulphide mounds to

  19. Occurrences of dendritic gold at the McLaughlin Mine hot-spring gold deposit

    Science.gov (United States)

    Sherlock, R. L.; Lehrman, N. J.

    1995-06-01

    Two styles of gold dendrites are variably developed at the McLaughlin Mine. The most abundant occurrence is hosted by amber-coloured hydrocarbon-rich opal. Silica likely precipitated from a boiling hydrothermal fluid and complexed with immiscible hydrocarbons forming an amorphous hydrocarbon-silica phase. This phase likely scavenged particulate gold by electrostatic attraction to the hydrocarbon-silica phase. The dendritic nature of the gold is secondary and is the result of dewatering of the amorphous hydrocarbon-silica phase and crystallization of gold into syneresis fractures. The second style of dendritic gold is hosted within vein swarms that focused large volumes of fluid flow. The dendrites occur along with hydrocarbon-rich silica at the upper contact of the vein margins which isolated the dendrites allowing sufficient time for them to grow. In a manner similar to the amber-coloured opal, the dendrites may have formed by scavenging particulate gold by electrostatic attraction to the hydrocarbon-silica phase.

  20. China Plans to Produce 260 Tons Gold & Find More Deposits

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>In 2006, China’s State Development and Reform Commission (SDRC) further strengthened its macro adjustment and administration work on the gold industry, leading it to establish a scientific development attitude with more structure adjustments and various reforms, which

  1. Enhancement of the photocatalytic activity of europium(III) oxide by the deposition of gold for the removal of atrazine

    Energy Technology Data Exchange (ETDEWEB)

    Aazam, E.S., E-mail: eaazam@yahoo.com

    2016-07-05

    Europium(III) oxide nanoparticles were prepared using a hydrothermal method. Gold was deposited by a photo-assisted deposition method. Europium(III) oxide and gold deposited europium(III) oxide were characterized using different techniques. The results demonstrated that gold was present as a metallic gold, and it was well-dispersed on the europium(III) oxide surface. The photocatalytic activity of europium(III) oxide and gold deposited europium(III) oxide was measured by the degradation of atrazine using visible light irradiation. The photocatalytic activity of gold deposited europium(III) oxide is higher than that of europium(III) oxide. This finding can be attributed to the synergic effect between europium(III) oxide and gold. Moreover, the results revealed that an increase in the weight percent of gold increases the photocatalytic activity of europium(III) oxide, and the most active photocatalyst is 0.20 wt % gold deposited europium(III) oxide. The photocatalyst of 0.20 wt % gold deposited europium(III) oxide has high photocatalytic stability and can be reused five times without a decrease in photocatalytic activity. - Highlights: • Au/Eu{sub 2}O{sub 3} nanocomposites were used for photocatalytic degradation of atrazine under visible light. • Photocatalytic degradation of atrazine under visible light was dependent on wt % of Au. • Catalyst re-use revealed the present photocatalyst remain effective and active after five cycles.

  2. Trace Elements in Fluid Inclusions in the Carlin-Type Gold Deposits, Southwestern Guizhou Province

    Institute of Scientific and Technical Information of China (English)

    苏文超; 胡瑞忠; 漆亮; 方维萱

    2001-01-01

    Fluid inclusions in quartz from the Lannigou and Yata Carlin-type gold deposits in southwestern Guizhou were analyzed by inductively coupled plasma-mass spectrometry for their trace elements (Co, Ni, Cu, Pb, Zn, Pt, etc. ). The results show that quartz fluid inclusions entrapped at different ore-forming stages contain higher Co, Ni, Cu, Pb and Zn. It has been found for the first time that the ore-forming fluids responsible for the Carlin-type gold deposits are rich in Pt. From this it can be concluded that basic volcanic rocks seem to be one of the im portant sources of ore-forming materials for the Carlin-type gold deposits.

  3. FORMATION OF GOLD-BEARING HYDROFRACTURING BRECCIA BODIES IN TECTONIC LENSES: A CASE STUDY ON SHUANGWANG GOLD DEPOSIT, SHAANXI, CHINA

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Macro-microscopic tectonic analysis and lithologic features show that the gold-bearing breccia bodies in the Shuangwang gold deposit, for hydrofracturing of the deep-sourced and alkali-rich fluids in the Devonian sodic rock series, are identified as hydrofracturing breccia bodies. Since the Indosinian,intracontinental collisional orogenesis results in multiple fracturings and magmatic emplacements in the Qinling area. Deep-sourced fluids resulting from deep fractures and granitoid magmatic intrusion are of a supercritical nature. Joint action between the fluid-rock system and structures leads to hydroffacturing and ore formation of the gold deposit.Firstly, the progressive coaxial compression caused the competent sodic rock series and the incompetent pelitic rock series to be deformed and partitioned. Lens-like weak-strain domains are hence formed and distributed at the approximate equidistance zones and the linear strong-strain zones,respectively. Subsequently, the progressive non-coaxial shearing and right-lateral and high-angle oblique thrusting lead to the most developed fracture system in the core of the weak-strain domain to turn from compression to extension and to link up with the deep fracture systems. The periodical huge pressure decline in the pumping center causes the deep-sourced confined fluids to develop periodic tectonic pumping, hydrofracturing and precipitation-healing in the sodic rock series. The gold-bearing hydrofracturing breccia bodies are hence ultimately formed at near-equidistance tectonic lenses. On the basis of the above model, the predicted concealed gold-bearing hydrofracturing breccia bodies have been preliminarily validated by latest drillings.

  4. The Muruntau gold deposit (Uzbekistan – A unique ancient hydrothermal system in the southern Tien Shan

    Directory of Open Access Journals (Sweden)

    Ulf Kempe

    2016-05-01

    Full Text Available The Muruntau gold deposit in the Central Kyzylkum, Uzbekistan is one of the largest single gold deposits worldwide. Data available from the literature are reviewed with the aim to (1 integrate the present knowledge on this unique deposit from Russian and English literature; (2 show the considerable progress made in the understanding of the genesis of the Muruntau deposit during the last decades; and (3 point to problems still open for future research. Deposit formation occurred through a multi-stage process involving sedimentation, regional metamorphism including thrusting, magmatism with formation of hornfels aureoles and several stages of hydrothermal activity. According to recent knowledge, synsedimentary or pure metamorphic formation of gold mineralization seems unlikely. The role of granite magmatism occurring roughly within the same time interval as the main hydrothermal gold precipitation remains uncertain. There are no signs of interaction of matter between the magma(s and the hydrothermal system(s. On the other hand, there was an intense, high-temperature (above 400 °C fluid – wall rock interaction resulting in the formation of gold-bearing, cone-like stockworks with veins, veinlets and gold-bearing metasomatites. Several chemical and isotope indicators hint at an involvement of lower-crustal or mantle-related sources as well as of surface waters in ore formation. Deposit formation through brecciation involving explosion, hydrothermal or tectonic breccias might explain these data. Further investigations on breccia formation as well as on the exact timing of relevant sedimentary, metamorphic, magmatic and hydrothermal events are recommended.

  5. The Muruntau gold deposit (Uzbekistan) e A unique ancient hydrothermal system in the southern Tien Shan

    Institute of Scientific and Technical Information of China (English)

    Ulf Kempe; Torsten Graupner; Reimar Seltmann; Hugo de Boorder; Alla Dolgopolova

    2016-01-01

    The Muruntau gold deposit in the Central Kyzylkum, Uzbekistan is one of the largest single gold deposits worldwide. Data available from the literature are reviewed with the aim to (1) integrate the present knowledge on this unique deposit from Russian and English literature; (2) show the considerable progress made in the understanding of the genesis of the Muruntau deposit during the last decades;and (3) point to problems still open for future research. Deposit formation occurred through a multi-stage process involving sedimentation, regional metamorphism including thrusting, magmatism with for-mation of hornfels aureoles and several stages of hydrothermal activity. According to recent knowledge, synsedimentary or pure metamorphic formation of gold mineralization seems unlikely. The role of granite magmatism occurring roughly within the same time interval as the main hydrothermal gold precipitation remains uncertain. There are no signs of interaction of matter between the magma(s) and the hydrothermal system(s). On the other hand, there was an intense, high-temperature (above 400 ?C) fluid e wall rock interaction resulting in the formation of gold-bearing, cone-like stockworks with veins, veinlets and gold-bearing metasomatites. Several chemical and isotope indicators hint at an involvement of lower-crustal or mantle-related sources as well as of surface waters in ore formation. Deposit for-mation through brecciation involving explosion, hydrothermal or tectonic breccias might explain these data. Further investigations on breccia formation as well as on the exact timing of relevant sedimentary, metamorphic, magmatic and hydrothermal events are recommended.

  6. Geological characteristics and ore-forming process of the gold deposits in the western Qinling region, China

    Science.gov (United States)

    Liu, Jiajun; Liu, Chonghao; Carranza, Emmanuel John M.; Li, Yujie; Mao, Zhihao; Wang, Jianping; Wang, Yinhong; Zhang, Jing; Zhai, Degao; Zhang, Huafeng; Shan, Liang; Zhu, Laimin; Lu, Rukui

    2015-05-01

    The western Qinling, belonging to the western part of the Qinling-Dabie-Sulu orogen between the North China Block and South China Block, is one of the most important gold regions in China. Isotopic dates suggest that the Mesozoic granitoids in the western Qinling region emplaced during the Middle-Late Triassic, and the deposits formed during the Late Triassic. Almost all gold deposits in the western Qinling region are classified as orogenic, Carlin-type, and Carlin-like gold deposits, and they are the products of Qinling Orogenesis caused by the final collision between the North China Block and the South China Block. The early subduction of the Mian-Lue oceanic crust and the latter collision between South Qinling Terrane and the South China Block along the Mian-Lue suture generated lithosphere-scale thermal anomalies to drive orogen-scale hydrothermal systems. The collision-related magmatism also provided heat source for regional ore-forming fluids in the Carlin-like gold deposits. Orogenic gold deposits such as Huachanggou, Liziyuan, and Baguamiao lie between the Shang-Dan and Mian-Lue sutures and are confined to WNW-trending brittle-ductile shear zones in Devonian and Carboniferous greenschist-facies metasedimentary rocks that were highly-deformed and regionally-metamorphosed. These deposits are typical orogenic gold deposits and formed within a Late Triassic age. The deposits show a close relationship between Au and Ag. Ores contain mainly microscopic gold, and minor electrum and visible gold, along with pyrite. The ore-forming fluids were main metamorphic fluids. Intensive tectonic movements caused by orogenesis created fluid-migrating channels for precipitation locations. Although some orogenic gold deposits occur adjacent to granitoids, mineralization is not synchronous with magmatism; that is, the granitoids have no genetic relations to orogenic gold deposits. As ore-forming fluids converged into dilated fractures during the extension stage of orogenesis

  7. The conjunction of factors that lead to formation of giant gold provinces and deposits in non-arc settings

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2016-05-01

    In contrast to their province scale similarities, the different giant gold deposit styles show contrasting critical controls at the district to deposit scale. For orogenic gold deposits, the giants appear to have formed by conjunction of a greater number of parameters to those that control smaller deposits, with resultant geometrical and lithostratigraphic complexity as a guide to their location. There are few giant IRGS due to their inferior fluid-flux systems relative to orogenic gold deposits, and those few giants are essentially preservational exceptions. Many Carlin-type deposits are giants due to the exceptional conjunction of both structural and lithological parameters that caused reactive and permeable rocks, enriched in syngenetic gold, to be located below an impermeable cap along antiformal “trends”. Hydrocarbons probably played an important role in concentrating metal. The supergiant Post-Betze deposit has additional ore zones in strain heterogeneities surrounding the pre-gold Goldstrike stock. All unequivocal IOCG deposits are giant or near-giant deposits in terms of gold-equivalent resources, partly due to economic factors for this relatively poorly understood, low Cu-Au grade deposit type. The supergiant Olympic Dam deposit, the most shallowly formed deposit among the larger IOCGs, probably owes its origin to eruption of volatile-rich hybrid magma at surface, with formation of a large maar and intense and widespread brecciation, alteration and Cu-Au-U deposition in a huge rock volume.

  8. Multistage gold mineralization in the Wa-Lawra greenstone belt, NW Ghana: The Bepkong deposit

    Science.gov (United States)

    Amponsah, Prince Ofori; Salvi, Stefano; Didier, Béziat; Baratoux, Lenka; Siebenaller, Luc; Jessell, Mark; Nude, Prosper Mackenzie; Gyawu, Eugene Adubofour

    2016-08-01

    The Bepkong gold deposit is one of several gold camps in the Paleoproterozoic Wa-Lawra greenstone belt in northwest Ghana. These deposits lay along the Kunche-Atikpi shear zone, which is part of the larger transcurrent Jirapa shear zone. The formation of these shear zones can be attributed to the general ESE-WNW major shortening that took place in the Wa-Lawra belt. Gold mineralization in the Bepkong deposit mainly occurs within graphitic shales and volcaniclastic rocks. The ore consists of four N-S trending lenticular bodies, plunging steeply to the south, that are lithologically and structurally controlled. Their shape and thickness are variable, though a general strike length of 560 m and an overall thickness of 300 m can be defined. An alteration mineral assemblage characterises the ore, and consists of chlorite-calcite-sericite-quartz-arsenopyrite-pyrite. Pyrite, as distinct from arsenopyrite, is not limited to the altered rocks and occurs throughout the area. At Bepkong, gold is associated with arsenopyrite and pyrite, which occur disseminated in the mineralized wall rock, flanking Type-1 quartz veins, or within fractures crossing these veins. Textural observations indicate the early formation of abundant arsenopyrite, followed by pyrite, with chalcopyrite, galena, sphalerite and pyrrhotite occurring as inclusions within pyrite and altered arsenopyrite. Detailed petrography, coupled with SEM, LA-ICP-MS and EMP analyses, indicate that gold in the Bepkong deposit occurs in three distinct forms: (i) invisible gold, mostly in arsenopyrite (ii); visible gold as micron-size grains within fractures and altered rims of arsenopyrite, as well as at the interface of sulphide grains; (iii) free visible gold in fractures in quartz veins and their selvages. We interpret the invisible gold to have co-precipitated with the early-formed arsenopyrite. The small visible gold grains observed within the sulphide interfaces, altered arsenopyrite, fractures and grain boundaries

  9. Database of significant deposits of gold, silver, copper, lead, and zinc in the United States

    Science.gov (United States)

    Long, Keith R.; DeYoung, Jr., John H.; Ludington, Stephen

    1998-01-01

    It has long been recognized that the largest mineral deposits contain most of the known mineral endowment (Singer and DeYoung, 1980). Sometimes called giant or world-class deposits, these largest deposits account for a very large share of historic and current mineral production and resources in industrial society (Singer, 1995). For example, Singer (1995) shows that the largest 10 percent of the world’s gold deposits contain 86 percent of the gold discovered to date. Many mineral resource issues and investigations are more easily addressed if limited to the relatively small number of deposits that contain most of the known mineral resources. An estimate of known resources using just these deposits would normally be sufficient, because considering smaller deposits would not add significantly to the total estimate. Land-use planning should treat mainly with these deposits due to their relative scarcity, the large share of known resources they contain, and the fact that economies of scale allow minerals to be produced much more cheaply from larger deposits. Investigation of environmental and other hazards that result from mining operations can be limited to these largest deposits because they account for most of past and current production.

  10. Age constraints of the Wassa and Benso mesothermal gold deposits, Ashanti Belt, Ghana, West Africa

    Science.gov (United States)

    Parra-Avila, Luis A.; Bourassa, Yan; Miller, John; Perrouty, Stéphane; Fiorentini, Marco L.; Campbell McCuaig, T.

    2015-12-01

    The Ashanti Belt in Ghana hosts numerous multi-million ounce gold deposits and is one of the most richly gold endowed Paleoproterozoic belts of the West African Craton. This work shows that the Wassa mineralized intrusion is part of the Sefwi Group. This unit at Wassa is strongly magnetic and show a distinctly high response in regional magnetic data sets compared to other units of equivalent age within the belt. The unit is inferred to be a lateral extension of an exposed fragment of what defines the substrate to the Tarkwa Basin sediments. The Wassa deposit, located in the eastern limb of the belt, is hosted within mafic to intermediate volcanic flows that are interbedded with minor horizons of volcaniclastics, clastic sediments. The clastic sediments include wackes and magnetite rich sedimentary layers, presumably derived from banded iron formations. The previously described sequence is intruded by syn-volcanic mafic intrusives and felsic porphyries rocks that are all part of the Birimian stratigraphy. Two new key SHRIMP II U-Pb ages were determined as part of this study: a new age of 2191 ± 6 Ma was determined on magmatic zircon grains of the Wassa porphyry host rock, which now represents the oldest known felsic intrusion hosting gold mineralization in the Ashanti Belt region. The Benso gold deposit system, which is located in the eastern limb of the Ashanti Belt approximately 38 km southwest of Wassa is hosted within a series of volcanic units intruded by mafic to intermediate units. A SHRIMP II U-Pb age of 2157 ± 5 Ma was determined from magmatic zircons obtained from a granodiorite of the G-Zone of the Benso deposit. This granodiorite is the main host rock for gold mineralization and thus the age provides an upper constraint for mineral emplacement. The newly determined ages provide an upper constraint for the gold mineralization within this region of the Ashanti Belt. They also support recent structural studies that have interpreted that the Wassa

  11. Ultra-small platinum and gold nanoparticles by arc plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Hoon, E-mail: kim_sh@kist.re.kr [Center for Materials Architecturing, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Jeong, Young Eun; Ha, Heonphil; Byun, Ji Young [Center for Materials Architecturing, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Kim, Young Dok [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-04-01

    Highlights: • Ultra-small (<2 nm) and bigger platinum and gold nanoparticles were produced by arc plasma deposition (APD). • Size and coverage of deposited nanoparticles were easily controlled with APD parameters. • Crystalline structures of deposited nanoparticles emerged only when the particle size was bigger than ∼2 nm. - Abstract: Ultra-small (<2 nm) nanoparticles of platinum and gold were produced by arc plasma deposition (APD) in a systematic way and the deposition behavior was studied. Nanoparticles were deposited on two dimensional amorphous carbon and amorphous titania thin films and characterized by transmission electron microscopy (TEM). Deposition behavior of nanoparticles by APD was studied with discharge voltage (V), discharge condenser capacitance (C), and the number of plasma pulse shots (n) as controllable parameters. The average size of intrinsic nanoparticles generated by APD process was as small as 0.9 nm and deposited nanoparticles began to have crystal structures from the particle size of about 2 nm. V was the most sensitive parameter to control the size and coverage of generated nanoparticles compared to C and n. Size of APD deposited nanoparticles was also influenced by the nature of evaporating materials and substrates.

  12. Geological and Geochemical Characteristics of the Zhulazhaga Gold Deposit in Inner Mongolia,China

    Institute of Scientific and Technical Information of China (English)

    JIANG Sihong; NIE Fengjun

    2005-01-01

    Located in Alxa Zuoqi (Left Banner) of Inner Mongolia, China, the Zhulazhaga gold deposit is the first largescale gold deposit that was found in the middle-upper Proterozoic strata along the north margin of the North China craton in recent years. It was discovered by the No. 1 Geophysical and Geochemical Exploration Party of Inner Mongolia as a result of prospecting a geochemical anomaly. By now, over 50 tonnes of gold has been defined, with an average Au grade of 4 g/t. The ore bodies occur in the first lithological unit of the Mesoproterozoic Zhulazhagamaodao Formation (MZF), which is composed mainly of epimetamorphic sandstone and siltstone and partly of volcanic rocks. With high concentration of gold,the first lithological unit of the MZF became the source bed for the late-stage ore formation. Controlled by the interstratal fracture zones, the ore bodies mostly appear along the bedding with occurrence similar to that of the strata. The primitive ore types are predominantly the altered rock type with minor ore belonging to the quartz veins type. There are also some oxidized ore near the surface. The metallic minerals are composed mainly of pyrite, pyrrhotite and arsenopyrite with minor chalcopyrite, galena and limonite. Most gold minerals appear as native gold and electrum. Hydrothermal alterations associated with the ore formation are actinolitization, silicatization, sulfidation and carbonation.A total of 100 two-phase H20-rich and 7 three-phase daughter crystal-bearing inclusions were measured in seven goldbearing quartz samples from the Zhulazhaga gold deposit. The homogenization temperatures of the two-phase H2O-rich inclusions range from 155 to 401℃, with an average temperature of 284℃ and bimodal distributions from 240 to 260℃ and 300 to 320℃ respectively. The salinities of the two-phase H20-rich inclusions vary from 9.22wt% to 24.30wt% NaCl equiv, with a mode between 23 wt% and 24wt% NaCl equiv. Comparatively, the homogenization temperatures of

  13. Friction and hardness of gold films deposited by ion plating and evaporation

    Science.gov (United States)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1983-01-01

    Sliding friction experiments were conducted with ion-plated and vapor-deposited gold films on various substrates in contact with a 0.025-mm-radius spherical silicon carbide rider in mineral oil. Hardness measurements were also made to examine the hardness depth profile of the coated gold on the substrate. The results indicate that the hardness is influenced by the depth of the gold coating from the surface. The hardness increases with an increase in the depth. The hardness is also related to the composition gradient in the graded interface between the gold coating and the substrate. The graded interface exhibited the highest hardness resulting from an alloy hardening effect. The coefficient of friction is inversely related to the hardness, namely, the load carrying capacity of the surface. The greater the hardness that the metal surface possesses, the lower is the coefficient of friction. The graded interface exhibited the lowest coefficient of friction.

  14. Crystalomorphological Characteristics of Pyrite in Hydrothermal Gold Deposit--An Experimental Study

    Institute of Scientific and Technical Information of China (English)

    蔡元吉; 周茂

    1994-01-01

    On the basis of the geological characteristics of primary gold deposits, with an experiment on modelling the environment of gold mineralization , the evolutionary array and growth mechanism and their relationship with gold mineralization of the crystal forms of pyrite, i. e. pentagonal dodecahedron, octahedron and cube, formed under the different values of fo2, fs2, T (℃), P(Pa) and C (salinity) in the hy-drothermal system are studied. The results show that the crystal form of pyrite is not only related to the temperature L, but also affected by the geochemistry of iron and sulfur which formed pyrite and other physicochemical conditions.Our results promote the study of gold mineralization, genetic and prospecting mineralogy.

  15. Control of favorable lithology on Jinlongshan micro-fine disseminated gold deposits, southern Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Liqing

    2002-01-01

    [1]Wells, J. D., Mullens, T. E., Gold-bearing arsenian pyrite determined by microprobe analysis, Cortze and Carlin gold mines, Nevada, Econ. Geol., 1973, 68: 187-201.[2]Boyle, R. W., The geochemistry of gold and its deposits, in Geological Survey Bulletin 280, Ottawa: Ministry of Supply and Services Canada, 1979, 307-310.[3]Liu, D., Geng, W., Mineralogy and discussion of metallogenic setting of Carlin-type gold deposits in China, Geochemistry (in Chinese with English abstr.), 1985, (3): 277-282.[4]Liu, D., Geng, W., China's Carlin-type gold deposits: Their geological features, genesis and exploration guides, Geology and Exploration (in Chinese with English abstr.), 1987, 23(12): 1-12.[5]Kuehn, C. A., Rose, A. W., Geology and geochemistry of wall-rock alteration at the Carlin gold deposit, Nevada, Econ. Geol., 1992, 87(7): 1697-1721.[6]Sillitoe, R. H., Bonham, H. F. Jr., Sediment-hosted gold deposits: Distal products of magmatic-hydrothermal systems, Geol., 1990,18: 157-161.[7]Berger, B. R., Bagby, W. C., The geology and origin of Carlin-type gold deposits, in Gold Metallogeny and Exploration (ed. Foster. R. P.), London: Chapman & Hall, 1991, 210-248.[8]Stenger, D. P., Kesler, S. E., Peltonen, D. R. et al., Deposition of gold in Carlin-type deposits: The role of sulfidation and decarbonation at Twin Creeks, Nevada, Econ. Geol., 1998, 93: 201-215.[9]Arehart, G. B., Characteristics and origin of sediment-hosted disseminated gold deposits: A review, Ore Geology Reviews, 1996, 11: 383-403.[10]Zhang, F., Ma, J., Wei, K., The relationship between the formation of the micro-disseminated stratabound gold deposits and the structural evolution in Miliang area, Zhen'an County (in Chinese with English abstr.), Mineral Deposits, 1995, 14(1): 26-34.[11]Zhang, G., Meng, Q., Lai, S., Structure of Qinling orogenic zone, Science in China (in Chinese), Ser. B, 1995, 25(9): 994-1003.[12]Zhang, B., Luo, T., Gai, S. et al., Geochemistry of

  16. Deposition of gold nanoparticles on glass substrate by ultrasonic spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Garza, Maria de la; Hernandez, Tomas [Laboratorio de Materiales I, Centro de Laboratorios Especializados, Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon. Av. Universidad s/n Cd. Universitaria, C.P. 66451, San Nicolas de los Garza, Nuevo Leon (Mexico); Colas, Rafael [Programa Doctoral en Ingenieria de Materiales, Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon. Av. Universidad s/n Cd. Universitaria, C.P. 66451, San Nicolas de los Garza, Nuevo Leon (Mexico); Gomez, Idalia, E-mail: mgomez@fcq.uanl.mx [Laboratorio de Materiales I, Centro de Laboratorios Especializados, Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon. Av. Universidad s/n Cd. Universitaria, C.P. 66451, San Nicolas de los Garza, Nuevo Leon (Mexico)

    2010-10-25

    Ultrasonic spray pyrolysis was used to deposit gold nanoparticles on a glass substrate using ZrO{sub 2} as a surrounding medium. The deposition was made using three flow rates of caring gas. The characterization was made by UV-Vis spectroscopy, X-ray diffraction, scanning electronic microscopy and atomic force microscopy. The UV-Vis spectra showed that the surface plasmon resonance peak, indicative of the presence of gold nanoparticles, was shown to shift towards the red spectrum as the flow rate increased; this shift can be associated to the change in size of the particles, which are assumed to grow on a {l_brace}1 1 1{r_brace} planes, as was detected by X-ray diffraction. Gold nanoparticles of spheroidal morphology with a relation of around 2:1 were detected by scanning electron microscopy, these observations were confirmed by atomic force microscopy.

  17. Sediment—Hosted Gold Deposits in China_geochemistry and Prospecting

    Institute of Scientific and Technical Information of China (English)

    杨蔚华; 刘友梅

    1997-01-01

    Sediment-hosted gold deposits are the major type of gold resources in china,Concen trated mostly in the two"Triangle Regios",they are generally hosted in fine-clastic turbidite,hydrothermal chet and marl ranging from cambrian to Triassic in age,structurally controlled by domes,anticlines and second-ordered faults.They are similar to the Carlin-type gold deposits in mineral assemblage and geochemical marks,with an element association closely comparable to those of modern springs and submarine hydrothermal sediments.Organic matter may have played an important role in mineralization .The ore solution may be hydrothermally altered meteoric water developed i areas of local geothermal anomaly.

  18. Geology and Genesis of the Superlarge Jinchang Gold Deposit, NE China

    Institute of Scientific and Technical Information of China (English)

    JIA Guozhi; CHEN Jinrong; YANG Zhaoguang; BIAN Hongye; WANG Yangzhong; LIANG Haijun; JIN Tonghe; LI Zhenhui

    2008-01-01

    The superlarge Jinchang gold deposit is located in the joint area between the Taipinglinguplift and the Laoheishan depression of the Xingkai Block in both eastern Jilin and easternHeilongjiang Province. Wall rocks of the gold deposits are the Neoproterozoic Huangsong Group ofmetamorphic rocks. Yanshanian magmatism in this region can be divided into 5 phases, the diorite,the graphic granite, the granite, the granite porphyry and the diorite porphyrite, which resulted in themagmatic domes and cryptoexplosive breecia chimney followed by large-scale hydrothermalalteration. Gold mineralization is closely related to the fourth and fifth phase of magmatism.According to the occurrences, gold ores can be subdivided into auriferous pyritized quartz vein,auriferous quartz-pyrite vein, auriferous polymetallic sulfide quartz vein and auriferous pyritizedcalcite vein. The ages of the gold deposit are ranging from 122.53 to 119.40 Ma. The ore bodies werecontrolled by a uniform tectono-magmatic hydrothermal alteration system that the ore-formingmaterials were deep derived from and the ore-forming fluids were dominated by magmatic waterswith addition of some atmospheric water in the later phase of mineralization. Gold mineralizationtook place in an environment of medium to high temperatures and medium pressures. Ore-formingfluids were the K+-Na+-Ca2+-Cl--SO42- type and characterized by medium salinity or a slightly higher,weak alkaline and weak reductive. Au in the ore-forming fluids was transported as complexes of [Au(HS)2]-, [AuCl2]-, [Au(CO2)]- and [Au(HCO3)2]-. Along with the decline of temperatures andpressures, the ore-forming fluids varied from acidic to weak acidic and then to weak alkaline, whichresulted in the dissociation of the complex and finally the precipitation of the gold.

  19. Nanoscale Soldering of Positioned Carbon Nanotubes using Highly Conductive Electron Beam Induced Gold Deposition

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    We have developed an in-situ method for controlled positioning of carbon nanotubes followed by highly conductive contacting of the nanotubes, using electron beam assisted deposition of gold. The positioning and soldering process takes place inside an Environmental Scanning Electron Microscope (E...

  20. Airborne Thermal Infrared Multispectral Scanner (TIMS) images over disseminated gold deposits, Osgood Mountains, Humboldt County, Nevada

    Science.gov (United States)

    Krohn, M. Dennis

    1986-01-01

    The U.S. Geological Survey (USGS) acquired airborne Thermal Infrared Multispectral Scanner (TIMS) images over several disseminated gold deposits in northern Nevada in 1983. The aerial surveys were flown to determine whether TIMS data could depict jasperoids (siliceous replacement bodies) associated with the gold deposits. The TIMS data were collected over the Pinson and Getchell Mines in the Osgood Mountains, the Carlin, Maggie Creek, Bootstrap, and other mines in the Tuscarora Mountains, and the Jerritt Canyon Mine in the Independence Mountains. The TIMS data seem to be a useful supplement to conventional geochemical exploration for disseminated gold deposits in the western United States. Siliceous outcrops are readily separable in the TIMS image from other types of host rocks. Different forms of silicification are not readily separable, yet, due to limitations of spatial resolution and spectral dynamic range. Features associated with the disseminated gold deposits, such as the large intrusive bodies and fault structures, are also resolvable on TIMS data. Inclusion of high-resolution thermal inertia data would be a useful supplement to the TIMS data.

  1. Geochemical and Isotopic Constrains on the Origin of Kaymaz Gold Deposit, Eskisehir, NW Turkey

    Science.gov (United States)

    Toygar, Ozlem; Sendir, Huseyin; Mutlu, Halim; Demirbilek, Mehmet

    2016-04-01

    The Alpine-Himalayan orogenic system produced several gold deposits in Turkey related to subduction, collision, post-collision and rifting processes. The Kaymaz gold deposit in mid-west Anatolia, 65 km southeast of Eskisehir city, is an orogenic gold deposit which formed in association with listwaenites. The gold occurrence is closely related to listwaenitization process and intense silicification. SiO2 content is up to 96% due to pervasive hydrothermal alteration. Listwaenites are enriched in Au, Ag and several metals in varying levels which are also variably correlated with other trace elements. Regarding rare earth element concentrations in the mineralized zone, light rare earth elements are found to display different variations with respect to gold content. It is proposed that these differences are due to the presence of more than one fluid type in the system and/or different phases which transported ore minerals at varying extent. According to microthermometric data on quartz samples, the temperature of the mineralization between 200°C-420°C and 3.9%-9.6% NaCl eq., the deposit is an epithermal-mesothermal type mineralization. δ18O compositions of quartz samples and calculated δ18OH2O values at homogenization temperatures indicate that boiling process and/or hydrothermal fluids affected the system at more than one stage. δ34S compositions of pyrite samples show a magmatic source for sulfur in the system probably originating from local granite intrusion in the area. Keywords: Kaymaz, Eskisehir, gold, geochemistry, stable isotopes, fluid inclusion

  2. Deposition of gold nanoparticles on silica spheres by electroless metal plating technique.

    Science.gov (United States)

    Kobayashi, Yoshio; Tadaki, Yohei; Nagao, Daisuke; Konno, Mikio

    2005-03-15

    A previously proposed method for metal deposition with silver [Kobayashi et al., Chem. Mater. 13 (2001) 1630] was extended to uniform deposition of gold nanoparticles on submicrometer-sized silica spheres. The present method consisted of three steps: (1) the adsorption of Sn(2+) ions took place on surface of silica particles, (2) Ag(+) ions added were reduced and simultaneously adsorbed to the surface, while Sn(2+) was oxidized to Sn(4+), and (3) Au(+) ions added were reduced and deposited on the Ag surface. TEM observation, X-ray diffractometry, and UV-vis absorption spectroscopy revealed that gold metal nanoparticles with an average particle size of 13 nm and a crystal size of 5.1 nm were formed on the silica spheres with a size of 273 nm at an Au concentration of 0.77 M.

  3. NUMERICAL SIMULATION OF THE STRUCTURAL STRESS FIELD OF BEIYA GOLD DEPOSIT

    Institute of Scientific and Technical Information of China (English)

    MA Deyun; GAO Zhenmin

    2003-01-01

    Based on the study about the geological background of Beiya Gold Deposit, numerical simulation was conducted about the three-dimensional structural stress field for Beiya Gold Deposit by applying finite element theory and by employing a linear elasticity model. Results of the simulation indicate that the Beiya syncline is a faulted basin, and a hidden fracture occurs in the west wing of the syncline.Under the action of the EW-trending compressive force, four nearly NS-trending fractures (groups) were generated in the stress stretching areas of the two wings of the syncline, and these fractures constitute favorable tectonic positions for the upward intrusion of porphyry magma and the occurrence of Au-Pb-Zn polymetallic deposits.

  4. Synchrotron radiation X-ray fluorescence analysis on altered mineral muscovite in gold deposit

    Institute of Scientific and Technical Information of China (English)

    TANG Yun-Hui; YUAN Wan-Ming; WANG Li-Hua; HAN Chun-Ming; HUANG Yu-Ying; HE Wei

    2005-01-01

    Synchrotron radiation X-ray fluorescence (SRXRF) microprobe was used to ananlyse altered mineral muscovite and its surrounding feldspar in Yuerya gold deposit. The major, minor and trace elements of the two minerals were detected and analyzed. SRXRF analysis showed that the Yuerya muscovite had a complex chemical composition, containing K, Fe, Ca, Ti, Cr, Mn, Co, Cu, Zn and many trace or ultra-trace elements. Since muscovite resulted from the alteration of hydrothermal ore fluid acting on feldspar (plagioclase), the difference of chemical composition between the two minerals shows the components of ore fluid, which are characterized by the enrichment of alkaline and alkaline-earth metal elements K, Ca and ore-associated elements Fe, Cu, Zn. And gold, silver and platinum, invisible under microscope, were detected in some areas of muscovite, but not found in feldspar. Especially platinum, a mantle material, is rarely seen in the earth crust but now found in the gold deposit of magmatic sources; its appearance approves the idea of mantle flux participating in the gold mineralization, which suggests that the tectonic event controlling gold mineralization in the Yuerya district is a mantle phenomenon.

  5. Geology of the florencia gold – telluride deposit (camagüey, cuba) and some metallurgical considerations

    OpenAIRE

    López K Jesús M.; Moreira Jesús; Gandarillas José

    2011-01-01

    This paper describes the results from a study of the Florencia gold-telluride deposit in Central Cuba, including mineralogical, petrographical, microprobe and chemical analysis. Valuable information is provided for the exploration, mining and processing of gold ores from other nearby deposits with similar characteristics. Results highlight changes in the mineralogical composition of the ores between the north and south sectors of the deposit, as reflected in metallurgical concentrates after b...

  6. Geochemistry of Rare Earth Elements in Aktishikan Gold Deposit,Xinjiang

    Institute of Scientific and Technical Information of China (English)

    袁峰; 周涛发; 等

    2002-01-01

    The characteristics and the models of rare earth elements in the geological bodies and the hydrothermal water balancel with the adamellite were comprehensivealy studied in Aktishikan gold deposit,Nurt area of Altay,Xinjiang,And the behavior of rare earth elements during metasomatic alteration was discussed by using the isocon method of Grant,The results show that the rare earth elements are inert during metasomatic alteration,the hydrotheraml water has no relation to the magmatic water,and the gold material sources mainly stem from the wall rock.

  7. Synthesis and characterization of gold nanoparticles supported on zinc oxide via the deposition-precipitation method

    OpenAIRE

    Yazid, Hanani; Adnan, Rohana; HAMID, Shafida Abdul; Farrukh, Muhammad Akhyar

    2010-01-01

    Gold nanoparticles supported on zinc oxide nanoparticles were synthesized at several pH levels via the deposition-precipitation (DP) method. The effects of pH on gold loading, particle size, and particle size distribution on the support were studied at the iso-electric point (IEP) as well as below and above the IEP of ZnO. The addition of the support significantly changed the pH of the solution. The effects of adjusting the pH before and after the addition of the support into the gol...

  8. Copper deposition and its replacement by platinum on a gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Misicak, Daniel; Ruthenburg, Travis C. [Department of Chemistry, University of California, Davis, CA 95616 (United States); Fawcett, W. Ronald, E-mail: wrfawcett@ucdavis.ed [Department of Chemistry, University of California, Davis, CA 95616 (United States)

    2010-11-01

    The decoration of single crystal gold electrodes with platinum using underpotential deposited copper as an intermediate has been studied in detail. It was found that a significant fraction of the copper is lost in the transfer process from the upd cell to the exchange cell. In addition the surface of the gold is not covered uniformly by the platinum. Nevertheless, acceleration of the electroreduction of oxygen was observed with a loading of 0.14 {mu}g cm{sup -2}. The structure of the decorating layer was studied by scanning electron microscopy and atomic force microscopy.

  9. Metallogeny of the Lannigou Sedimentary Rock-hosted Disseminated Gold Deposit in Southwestern Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)

    BAO Zhiwei; Jayanta GUHA

    2007-01-01

    The Lannigou deposit is a large-sized sedimentary rock-hosted disseminated gold (SRHDG)deposit located in the Youjiang Basin. It is hosted by the Middle Triassic turbidite. Wall rock alterations, including silicification, pyritization, arsenopyritization, carbonatization and argillization,commonly occur along fractures. PGE study demonstrates that either Permian basalts or Triassic ultrabasic intrusives are unlikely to be the main source of gold mineralization. Coupled with the lack of other magmatic activity in the vicinity of the mining area, an amagmatic origin is proposed. Organic matter compositions and GC-MS analysis of the ores and host rocks show that the organics in the ores and the host rocks have a common source; the organic matter in the ores was mainly indigenous. The positive correlation between S2 and Au contents, along with the common occurrence of organic inclusions, suggest involvement of organic matter in the ore-forming process in terms of promoting Au leaching from the source rocks, making colloidal Au migration possible, as well as hydrocarbon reduction of sulphate. Geological and geochemical characteristics of the Lannigou deposit suggest that it was formed through circulation of meteoric water and probably less importantly organic bearing formation water driven by high geothermal gradient caused by late Yanshanian extension, which leached Au from the source bed, and then migrated as Au-bisulfides and colloidal Au, culminating in deposition by reduction-adsorption and surface complexation of gold onto the growth surface of arsenian pyrite.

  10. Quantification constraints on time gap for comagmatic gold deposits: Evidence from chronological statistics

    Institute of Scientific and Technical Information of China (English)

    TAN Jun; WEI Junhao; LI Shuiru; ZHANG Chunhua; LI Yanjun; GUO Lingli; YAN Yunfei

    2008-01-01

    The time gap between diagenesis and mineralization (TGDM) for comagmatic gold deposits (CGD) plays an important role in confirming the genetic relationship between gold deposits and their related intrusions. With the help of preciously published isotopic ages of some typical gold deposits and their related rocks in China, the authors have discussed and quantified the distribution characteristics and scope of the TGDM. Statistical analyses and Kolmogorov tests showed that mineralizing events are either contemporaneous with or slightly postdate their cognate magma. The TGDM conforms with normal distributions at a 0.05 confidence level and clusters between 0 and 16.0 Ma with a mean of 7.0 Ma. Thus, if the TGDM of CGD is less than 16.0 Ma, it is reasonable to consider, with the aid of other evidence, the possibility of its comagmatic genetic affiliation. The authors also emphasized that to get a precise time gap it is necessary to strengthen the diagenesis-mineralization geological background of the deposits studied, and to pay attention to the study of time gap in combination with trace elements and isotope tracing.

  11. Geochemical Features and Formation of the Auriferous Cherts in the Mojiang Gold Deposit, Yunnan

    Institute of Scientific and Technical Information of China (English)

    应汉龙; 蔡新平; 刘秉光

    2001-01-01

    Auriferous cherts in the Middle Carboniferous Jinchang Formation are the dominant host rocks of auriferous quartz veins and mixed orebodies comprised of gold-bearing quartz veins and cherts in the Mojiang gold deposit. The rocks exhibit sedimentary texture and structure and are composed of hot-water deposited minerals.The FeO, Fe2O3, Au and Ag contents of the auriferous cherts are high; the Cr, Ni and Cotonrents are also high but significantly vari able; MnO/TiO2 and TFe/TiO2 ratios are relatively high. As viewed from a few diagrams that distinguish different chert formations, the auriferous cherts are in or near the range of hot-wa ter deposited cherts. Because the correlation coefficients between Au contents and those of CrNi of the rocks are negative, a great Au amount in the cherts might not be brought about by later hydrothermal alterations. The rare-earth elements, O and Si isotopic compositions of the auriferous cherts demonstrate that the cherts belong to hot-water deposited rocks. The later hydrothermal alterations made the petrochemical compositions of the cherts deviate from the characteristics of hot-water deposition. In general, the geological and geochemical features of the auriferous cherts demonstrate that the rocks were formed by hot water deposition.

  12. Incorporation of gold into silicon by thin film deposition and pulsed laser melting

    Science.gov (United States)

    Warrender, Jeffrey M.; Hudspeth, Quentin; Malladi, Girish; Efstathiadis, Harry; Mathews, Jay

    2016-12-01

    We report on the incorporation of gold into silicon at a peak concentration of 1.9 × 1020 at./cm3, four orders of magnitude above the equilibrium solubility limit, using pulsed laser melting of a thin film deposited on the silicon surface. We vary the film thickness and laser process parameters (fluence, number of shots) to quantify the range of concentrations that can be achieved. Our approach achieves gold concentrations comparable to those achieved with ion implantation followed by pulsed laser melting, in a layer with high crystalline quality. This approach offers an attractive alternative to ion implantation for forming high quality, high concentration layers of transition metals like gold in silicon.

  13. Deposition of gold nanoparticles onto thiol-functionalized multiwalled carbon nanotubes.

    Science.gov (United States)

    Zanella, Rodolfo; Basiuk, Elena V; Santiago, Patricia; Basiuk, Vladimir A; Mireles, Edgar; Puente-Lee, Iván; Saniger, José M

    2005-09-01

    Gold nanoparticles were deposited on the surface of multiwalled carbon nanotubes (MWNTs) functionalized with aliphatic bifunctional thiols (1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, and 2-aminoethanethiol) through a direct solvent-free procedure. Small gold particles, with a narrow particle size distribution around 1.7 nm, were obtained on 1,6-hexanedithiol-functionalized MWNTs. For MWNTs functionalized with the aminothiol, the average Au particle size was larger, 5.5 nm, apparently due to a coalescence phenomenon. Gatan image filter (GIF) observations show that sulfur is at the nanotube surface with a non-homogeneous distribution. A higher sulfur concentration was observed around the gold nanoparticles' location.

  14. Monodisperse gold nanoparticles formed on bacterial crystalline surface layers (S-layers) by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dieluweit, S. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Pum, D. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Sleytr, U.B. [Center for Nanobiotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Gregor Mendel-Strasse 33, A-1180 Vienna (Austria); Kautek, W. [Department for Physical Chemistry, University of Vienna, Waehringer Strasse 42, A-1090 Vienna (Austria)]. E-mail: wolfgang.kautek@univie.ac.at

    2005-12-15

    The fabrication of patterned arrays of nanoparticles whose electronic, optical and magnetic properties will find technological applications, such as ultra-high-density memories, is currently one of the most important objectives of inorganic material research. In this study, the in situ electroless nucleation of ordered two-dimensional arrays of gold nanoparticles (5 nm in size) by using bacterial S-layers as molecular templates and their characterization by small spot X-ray photoelectron emission spectroscopy (XPS) is presented. This yielded the elemental composition of the nanoclusters, which consisted of almost entirely elemental gold, and possible side reactions on the cluster and protein surface. The preferential deposition of the gold nanoparticles on the S-layer suggests that topography and functional groups are important for superlattice formation.

  15. Geological significance of componential characteristics of pyrite from Shibaqinghao gold deposit in central Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Yihong Liang; Hongying Zhang; Yanhua Ma

    2006-01-01

    There are two types of gold ore in Shibaqinghao gold deposit, mylonite ore and quartz vein ore. Pyrite accompanying with native gold in mylonite ore has Fe from 43.66 to 45.32 wt% and S from 52.64 to 53.55 wt%. It is clear that this kind of pyrite is poor in both sulphur and iron. That means that the mylonite ore may be related to metamorphic water. Pyrite in the quartz vein ore has Fe from 44.38 to 45.30 wt% and S from 53.08 to 54.00 wt%. It means that this kind of pyrite is poor in iron but rich in sulphur, while the quartz vein ore may be related to magma water.

  16. The conjunction of factors that lead to formation of giant gold provinces and deposits in non-arc settings

    Science.gov (United States)

    Groves, David I.; Goldfarb, Richard J.; Santosh, M.

    2016-01-01

    It is quite evident that it is not anomalous metal transport, nor unique depositional conditions, nor any single factor at the deposit scale, that dictates whether a mineral deposit becomes a giant or not. A hierarchical approach thus is required to progressively examine controlling parameters at successively decreasing scales in the total mineral system to understand the location of giant gold deposits in non-arc environments. For giant orogenic, intrusion-related gold systems (IRGS) and Carlin-type gold deposits and iron oxide-copper-gold (IOCG) deposits, there are common factors among all of these at the lithospheric to crustal scale. All are sited in giant gold provinces controlled by complex fundamental fault or shear zones that follow craton margins or, in the case of most Phanerozoic orogenic giants, define the primary suture zones between tectonic terranes. Giant provinces of IRGS, IOCG, and Carlin-type deposits require melting of metasomatized lithosphere beneath craton margins with ascent of hybrid lamprophyric to granitic magmas and associated heat flux to generate the giant province. The IRGS and IOCG deposits require direct exsolution of volatile-rich magmatic-hydrothermal fluids, whereas the association of such melts with Carlin-type ores is more indirect and enigmatic. Giant orogenic gold provinces show no direct relationship to such magmatism, forming from metamorphic fluids, but show an indirect relationship to lamprophyres that reflect the mantle connectivity of controlling first-order structures.

  17. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    Science.gov (United States)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.

    2017-03-01

    Nalunaq is an orogenic, high gold grade deposit situated on the Nanortalik Peninsula, South Greenland. Mineralisation is hosted in shear zone-controlled quartz veins, located in fine- and medium-grained amphibolite. The deposit was the site of Greenland's only operating metalliferous mine until its closure in 2014, having produced 10.67 t of gold. This study uses a combination of field investigation, petrography and U/Pb zircon and titanite geochronology to define a multi-stage hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chlorite-plagioclase-löllingite-tourmaline-titanite), which is best developed in areas of exceptionally high gold grades. Aplite dykes dated to ca. 1762 Ma cross-cut the gold-quartz veins, providing a minimum age for mineralisation. A hydrothermal calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated, and as a result, its field relationships are poorly constrained. The hydrothermal alteration and mineralisation is cut by several generations of ca. 1745-Ma biotite granodiorite accompanied by brittle deformation. A ca. 1745-Ma lower greenschist facies hydrothermal epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting hydrothermal alteration styles at Nalunaq indicate a complex history of exhumation from amphibolite facies conditions to lower greenschist facies conditions in an orogenic belt which resembles modern Phanerozoic orogens.

  18. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    Science.gov (United States)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.

    2016-07-01

    Nalunaq is an orogenic, high gold grade deposit situated on the Nanortalik Peninsula, South Greenland. Mineralisation is hosted in shear zone-controlled quartz veins, located in fine- and medium-grained amphibolite. The deposit was the site of Greenland's only operating metalliferous mine until its closure in 2014, having produced 10.67 t of gold. This study uses a combination of field investigation, petrography and U/Pb zircon and titanite geochronology to define a multi-stage hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chlorite-plagioclase-löllingite-tourmaline-titanite), which is best developed in areas of exceptionally high gold grades. Aplite dykes dated to ca. 1762 Ma cross-cut the gold-quartz veins, providing a minimum age for mineralisation. A hydrothermal calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated, and as a result, its field relationships are poorly constrained. The hydrothermal alteration and mineralisation is cut by several generations of ca. 1745-Ma biotite granodiorite accompanied by brittle deformation. A ca. 1745-Ma lower greenschist facies hydrothermal epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting hydrothermal alteration styles at Nalunaq indicate a complex history of exhumation from amphibolite facies conditions to lower greenschist facies conditions in an orogenic belt which resembles modern Phanerozoic orogens.

  19. Tetrahedrite-Group Minerals in the Jinjitai Gold Deposit, Western Sichuan

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    There are quite a few tetrahedrite-group minerals in the Jinjitai gold deposit, western Sichuan, which occur in an interstratified fractured zone of Middle Devonian carbonate rock series. The gold ore consists of pyrite, chalcopyrite, tetrahedrite-group minerals, galena, sphalerite and gold-silver series minerals, with an element association of Au-Cu-Ag-Pb-As-Sb-Bi. Electron microprobe analyses of the tetrahedrite-group minerals gave the following results: copper 40.04 to 42.27% (average 40.04%), iron 1.24 to 7.78% (average 4.13%), zinc 0.39 to 7.06% (average 3.58%), arsenic 5.41 to 17.40% (average 8.84%), antimony 2.70 to 20.46% (average 15.87%), and silver 0.02 to 0.73% (average 0.28%). The mineral varieties include zinc-antimony-tetrahedrite, iron-antimony-tetrahedrite, iron-tennatite and zincotennatite. These data show that there is a complete isomorphous series between Sb and As. From above downwards tetrahedrite varies from zinc- and antimony-rich to iron- and arsenic-rich compositions. Their occurrence and zonal features are very important for exploration of the same type of gold deposits in western Sichuan.

  20. Au-Sb association and fractionation in micro-disseminated gold deposits,southwestern Guizhou--geochemistry and thermodynamics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The dual geochemical character of paragenesis and fractionation between gold,arsenic and antimony in micro-disseminated gold deposits in southwestern Guizhou is discussed in terms of spatial distribution of independent deposits,lateral and vertical enrichment,mineralization stage and factor and correlation analyses.Thermodynamic calculations of solubility and speciation of gold and antimony minerals indicate that gold is transported in hydrothermal solution as Au(HS)-2 and antimony is mainly as Sb(OH)03 although HSb2S-4 may be of increasing importance in acid environment at low temperatures during the late stage of mineralization.Changes in physicochemical conditions hold the key to the association and fractionation between gold and antimony.Gold and antimony response differently to physicochemical variations because they are distinct from each other in soluble speciation and mineral solubility,leading to precipitation at different times and localities during hydrothermal evolution.

  1. The Berezitovoe gold-polymetallic deposit (Upper Amur region, Russia):Structure, mineralogy and genetic aspects

    Institute of Scientific and Technical Information of China (English)

    Alexandr S. Vakh; Vadim G. Khomich; Natalia G. Boriskina; M. Santosh

    2016-01-01

    The Berezitovoe deposit in the Sergachi volcano-plutonic and metallogenic belt preserves evidence for polymetallic mineralization of multiple stages. The steeply dipping garnet-tourmaline-muscovite-quartz metasomatites (with K-Ar ages of 132 ? 2.9 and 127 ? 4.4 Ma) carry two distinct stages of mineralization developed at different times:(1) polymetallic mineralization and (2) gold-quartz. The deposit is located within Paleozoic gneissose granitoids of the Pikansky complex (dated as 379 ? 1.1 Ma by zircon U-Pb method) intruded by early Cretaceous porphyry-like granites of the Haikta pluton (dated as 137 ? 0.67 Ma by zircon U-Pb method) and late Cretaceous dikes of porphyrites, porphyries, and lamprophyres. Evidence suggests the action of late gold-bearing hydrothermal fluids on the early pol-ymetallic ores and the selective mobilization of some elements from these lead to redeposition together with complex sulphosalts.

  2. Province-scale commonalities of some world-class gold deposits:Implications for mineral exploration

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; M. Santosh

    2015-01-01

    Discovery rates for all metals, including gold, are declining, the cost per significant discovery is increasing sharply, and the economic situation of the industry is one of low base rate. The current hierarchical structure of the exploration and mining industry makes this situation difficult to redress. Economic geologists can do little to influence the required changes to the overall structure and philosophy of an industry driven by business rather than geological principles. However, it should be possible to follow the lead of the oil industry and improve the success rate of greenfield exploration, necessary for the next group of lower-exploration-spend significant mineral deposit discoveries. Here we promote the concept that mineral explorers need to carefully consider the scale at which their exploration targets are viewed. It is necessary to carefully assess the potential of drill targets in terms of terrane to province to district scale, rather than deposit scale, where most current economic geology research and conceptual thinking is concentrated. If orogenic, IRGD, Carlin-style and IOCG gold-rich systems are viewed at the deposit scale, they appear quite different in terms of conventionally adop-ted research parameters. However, recent models for these deposit styles show increasingly similar source-region parameters when viewed at the lithosphere scale, suggesting common tectonic settings. It is only by assessing individual targets in their tectonic context that they can be more reliably ranked in terms of potential to provide a significant drill discovery. Targets adjacent to craton margins, other lithosphere boundaries, and suture zones are clearly favoured for all of these gold deposit styles, and such exploration could lead to incidental discovery of major deposits of other metals sited along the same tectonic boundaries.

  3. Bacterial Deposition of Gold on Hair: Archeological, Forensic and Toxicological Implications

    OpenAIRE

    Genevieve Phillips; Frank Reith; Clifford Qualls; Abdul-Mehdi Ali; Mike Spilde; Otto Appenzeller

    2010-01-01

    BACKGROUND: Trace metal analyses in hair are used in archeological, forensic and toxicological investigations as proxies for metabolic processes. We show metallophilic bacteria mediating the deposition of gold (Au), used as tracer for microbial activity in hair post mortem after burial, affecting results of such analyses. METHODOLOGY/PRINCIPAL FINDINGS: Human hair was incubated for up to six months in auriferous soils, in natural soil columns (Experiment 1), soils amended with mobile Au(III)-...

  4. Geology, Geochemistry and Genesis of the Hongshijing Gold Deposit in Ruoqiang,Xinjiang

    Institute of Scientific and Technical Information of China (English)

    肖惠良; 周济元; 王鹤年; 崔炳芳; 陈世忠

    2003-01-01

    The Hongshijing gold deposit, which occurs in the Middle and Late Carboniferousvolcanic and pyroclastic rocks, is of the brittle-ductile shear zone type controlled by a rift belt.The Hongshijing gold deposit is one controlled by a brittle shear zone located in the Late Paleo-zoic rift zone. The altered-rock type and quartz type orebodies are contained in the gold-bearingformation, which consists of basalt and tuffaceous sandstone. The major mineralizing stage is at267 -261 Ma and reiteration mineralizing stage at 220 -209 Ma. The ore minerals include py-rite, magnetite, copper, bornite, ferrohydrite, native gold, and the gangue minerals includequartz, sercite, calcite, Fe-dolomite, leucoxene, anorthose, biotite, baria, cajuelite, andagustite. The wall rock alteration associated with gold mineralization comprises silicification,carbonization, pyritization, sericitization and chloritization. The contents of gold are 2.4 × 10-9in the gold-bearing formation, 5.7 × 10-9 in the tuffaceous sandstone and 1.4 - 1.5 × 10 9 inthe basalt. Au is associated with Te, Se, Ni, Cu. Au = 74.331 × Te + 0. 0335 × Ni - 0.0211 ×Cu- 2. 650. Geochemical investigations revealed that the mineralizing materials came from thebasalt and tuffaceous sandstone in the gold-bearing formation. Under the action of ductile brittleshear structure, the gold-bearing formation was metamorphosed and altered, and the ore-formingmaterials activated, migrated and mineralized. The mineralizing fluid shows three mineralizingstages, with the characteristics of middle to low temperature (381 - 115℃ ) and middle to lowmass fractions of NaCl (2.18% -16.77% ). The fluid is of the Ca2+ -Mg2+ -Na+ -Cl- type andH2O-NaCl system. According to the data from hydrogen and oxygen isotopic composition (δD =- 114.6‰ - - 68.8‰, δ 18 OH2O = - 2.47‰ - 5.91‰), the conclusion can be drawn thatthe mineralizing fluid of the Hongshijing gold deposit was a kind of mixed hydrothermal solutioncomposed mainly of meteoric

  5. Mineralogy and fluid inclusion studies in kalchoye Copper- gold deposit, East of Esfahan

    Directory of Open Access Journals (Sweden)

    Rezvan Mehvary

    2009-09-01

    Full Text Available Kalchoye Copper-gold deposit is located about 110 kilometers east of Esfahan province and within the Eocene volcano sedimentary rocks. Sandy tuff and andesite lava are important members of this complex.The form of mineralization in area is vein and veinlet and quartz as the main gangue phase. The main ore minerals are chalcopyrite, chalcocite, galena and weathered minerals such as goethite, iron oxides, malachite and azurite. Studies in area indicate that ore mineralization Kalchoye is low sulfide, quartz type of hydrothermal ore deposits and results of thermometry studies on quartz minerals low- medium fluid with low potential mineralization is responsible for mineralization in this area.

  6. The dilemma of the Jiaodong gold deposits:Are they unique?

    Institute of Scientific and Technical Information of China (English)

    Richard J. Goldfarb; M.; Santosh

    2014-01-01

    The ca. 126e120 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. 165e150 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 Pre-cambrian 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 “Yan-shanian”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 de-posits, in contrast, formed within two Precambrian blocks approximately 2 billion years after devolati-lization of the country rocks, and thus require a model that involves alternative fluid and metal sources for the ores. A widespread suite of ca. 130e123 Ma granodiorites overlaps temporally with the ores, but shows a poor spatial association with the deposits. Furthermore, the deposit distribution and mineral-ization 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

  7. Structural and alteration controls on gold mineralization the of the amphibolite facies Detour Lake Deposit, Canada

    Science.gov (United States)

    Dubosq, Renelle; Schneider, David

    2016-04-01

    The 15M oz Detour Lake deposit is a Neoarchean orogenic gold ore body located in the northern most region of the Abitibi district within the Superior Province. The mine is an open pit design in the high strain zone of the Sunday Lake Deformation Zone (SLDZ). The ductile-brittle SLDZ parallels the broadly E-W Abitibi greenstone belt and the deposit is situated in a dilation zone between volcanoclastic rocks of the Caopatina Assemblage and Lower Detour Lake Formation, consisting of ultramafic talc-chlorite-sericite schist. The Upper Detour Lake Formation consists of pillowed and massive flows and hyloclastic units crosscut by minor felsic to intermediate dykes. All of the formations are sub-vertical, north-dipping units with stretching lineations indicating dip-slip motion. The Detour deposit differs from other classic ore deposits in the dominantly greenschist facies Abitibi Subprovince by possessing an amphibolite facies metamorphic assemblage of actinolite-biotite-plagioclase-almandine. Consequently, the typical indicator minerals used to identify alteration and mineralization, such as secondary biotite, may not be useful. Petrological and geochemical analyses have revealed at least four populations of biotite: 1) large euhedral crystals located within quartz-carbonate veins, 2) small, euhedral zoned crystals present as alteration haloes, 3) very small, anhedral to subhedral indistinct crystal present in mafic volcanic host rock, and 4) large euhedral crystals defining the main metamorphic foliation in the metasediments. Extensive examination of mineral assemblages, alteration products, and vein structure in rock core across barren and mineralized zones has documented over a dozen vein types which can be grouped into two main categories: 1) sulfidized quartz-carbonate veins associated with biotite alteration and 2) late carbonate veins. Gold grades do not prove to be dependent on vein type but rather on the host rock composition: the highest ore grades are present

  8. Province-scale commonalities of some world-class gold deposits: Implications for mineral exploration

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2015-05-01

    Here we promote the concept that mineral explorers need to carefully consider the scale at which their exploration targets are viewed. It is necessary to carefully assess the potential of drill targets in terms of terrane to province to district scale, rather than deposit scale, where most current economic geology research and conceptual thinking is concentrated. If orogenic, IRGD, Carlin-style and IOCG gold-rich systems are viewed at the deposit scale, they appear quite different in terms of conventionally adopted research parameters. However, recent models for these deposit styles show increasingly similar source-region parameters when viewed at the lithosphere scale, suggesting common tectonic settings. It is only by assessing individual targets in their tectonic context that they can be more reliably ranked in terms of potential to provide a significant drill discovery. Targets adjacent to craton margins, other lithosphere boundaries, and suture zones are clearly favoured for all of these gold deposit styles, and such exploration could lead to incidental discovery of major deposits of other metals sited along the same tectonic boundaries.

  9. Trace element mapping of pyrite from Archean gold deposits – A comparison between PIXE and EPMA

    Energy Technology Data Exchange (ETDEWEB)

    Agangi, A., E-mail: aagangi@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa); Przybyłowicz, W., E-mail: przybylowicz@tlabs.ac.za [Materials Research Department, iThemba LABS, National Research Foundation, Somerset West 7129 (South Africa); AGH University of Science and Technology, Faculty of Physics & Applied Computer Science, Al. A. Mickiewicza 30, 30-059 Krakow (Poland); Hofmann, A., E-mail: ahofmann@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa)

    2015-04-01

    Chemical zoning of pyrites can record the evolution of mineralising fluids at widely varying P–T conditions ranging from diagenesis to medium-grade metamorphism. If preserved, zoning can reveal growth textures, brecciation and veining, resorption and recrystallisation events, thus shedding light on the processes that contributed to ore formation. Chemical zoning of sulfides is invisible in optical microscopy, but can be studied by chemical etching, high-contrast back-scattering electron images, and elemental imaging. In this study we compared micro-PIXE and WDS-EPMA elemental maps on the chemically zoned pyrites in mineralised vein-bearing samples from the Sheba and Fairview gold mines in the Barberton Greenstone Belt, South Africa. Elemental images show complex distribution of trace elements, suggesting multiple events of pyrite crystallisation and gold deposition. EPMA maps show fine-scale variations reflecting growth and recrystallisation textures marked, in particular, by variations of As, Ni, and Co. In PIXE maps, gold occurs both as finely-distributed and discrete inclusions, suggesting incorporation in the pyrite structure as solid solution, and deposition as electrum inclusions, respectively. Micro-PIXE and EPMA provide complementary information, forming together a powerful tool to obtain information on chemical zoning of pyrites in ore deposits.

  10. Synthesis and characterization of gold-deposited red, green and blue fluorescent silica nanoparticles for biosensor application.

    Science.gov (United States)

    Lee, Kyoung G; Wi, Rinbok; Park, Tae Jung; Yoon, Sun Hong; Lee, Jaebeom; Lee, Seok Jae; Kim, Do Hyun

    2010-09-14

    Fluorescent silica nanoparticles deposited with highly monodisperse gold nanoparticles (1-2 nm) were synthesized via the W/O method and intensive ultrasound irradiation. A large surface area of gold-doped fluorescent silica nanoparticle serves as a platform to immobilize a specific binding protein for biomolecules interaction in bioimaging applications.

  11. In Situ Synthesis and Deposition of Gold Nanoparticles with Different Morphologies on Glass and ITO Substrate by Ultrasonic Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    María de la Garza

    2013-01-01

    Full Text Available Gold nanoparticles were synthesized and deposited in situ by ultrasonic spray pyrolysis on glass and indium tin oxide (ITO substrates. This technique led to the formation of gold nanoparticles with different morphologies without the use of any capping agent. The gold nanoparticles deposited on glass substrate were obtained as nanospheres with an average particle size of 30 nm with some agglomerates; however, the nanoparticles deposited on ITO substrate were obtained with different morphologies, such as triangular nanoprisms, nanorods, nanocubes, and nanorhombus, with particle sizes between 40 and 100 nm. The ITO substrate influenced the morphology of the gold nanoparticles obtained due to changes in the deposition temperature, which also change the crystalline structure of the ITO film on the substrate.

  12. Underpotential deposition of a copper monolayer on a gold film sensed by integrated optical surface plasmon resonance

    OpenAIRE

    Abanulo, J.C.; Harris, R.D.; Bartlett, P.N.; Wilkinson, J.S.

    2000-01-01

    An integrated optical surface plasmon resonance sensor combined with electrochemical control is used to monitor the underpotential deposition of a copper monolayer onto a gold film from 1 mM Cu2+ in 0.1 M perchloric acid.

  13. Geology, Geochemistry and Genesis of the Mazhuangshan Gold Deposit in Hami,East Tianshan, Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    陈世忠; 周济元; 顾连兴; 崔炳芳; 肖惠良

    2001-01-01

    The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc, where there are distributed intermediate-acid magmatic rocks emplaced during the Middle-Late Carboniferous. There are more than 20 orebodies in the area with an average gold grade 6.4 ×10- 6 at present. The dominant metallic minerals are natural gold, auriferous silver, natural silver, pyrite and galena. Pyrite is the key gold carrier, high in Fe and low in S. Wall-rock alterations mainly include pyritization, silicification, and sericitization. Carbonation alteration was extensive at the late stage, often resulting in a high-grade orebody. Three mineralization stages may be distinguished.The peak homogenization temperatures of primary fluid inclusions range from 240 to 260℃. Mineralization pressures and depths are 47.2 - 68.8 MPa and 1 . 6 - 2.3 km respectively, showing the ore-forming features of hypergene gold deposit. The average salinity is 15wt% NaCl equivalent. Fluid inclusion geochemistry data show that Ca2 + is far higher than Mg2+, and mK+/mNa+, m2Na+/mca2+ (0.001 ~ 0.338), m∑cl/m∑s and m∑c/m∑s ratios change with the reduction parameter [ R = (CO + CH4)/CO2] and temperature. And the gold contents of ores and gangues are positively correlated with R.The pH values of inclusion water in quartz range from 5.8 to 7.4. Oxygen fugacity (fo2 )ranges from 10- 55 Pa to i0- 47 Pa, sulfur fugacity (fs2) is about 10- 13, and Eh values are estimated to be about - 0.6 eV. The δ 34S values of the fluid were determined to be + 3.94‰ to + 4.98‰. 206pb/204pb and 207pb/208pb ratios in pyrite are 18. 269 - 18. 352,15. 550 - 15. 633 and 38. 077 - 38. 355, respectively. The ∑REE values (4.7 × 10-6 ~ 43.1× 10-6) of ores and gangues are obviously lower than those of the host magmatic rocks, but their REE and trace element spider diagrams are similar to those of the host magmatic rocks,suggesting that the water consists dominantly of meteoric water, mixed with a part of magmatic

  14. Using ASD data to identify the altered minerals for exploring of gold deposit in the Beishan area, North China

    Science.gov (United States)

    Ren, G. L.; Yi, H.; Yang, M.; Liang, N.; Li, J. Q.; Yang, J. L.

    2016-11-01

    Hyperspectral information of altered minerals plays an important role in the identifications of mineralized zones. In this study, the altered minerals of two gold deposits from Fangshankou-Laojinchang regions of Beishan metallogenic belt were measured by ASD field Spectrometer. Many gold deposits would have a close relationship with Variscan magma intrusion, which have been found in study region. The alteration minerals have been divided six types by the spectral results, i.e. sericite, limonite, dolomite, chlorite, epidote and calcite. The distribution characteristics and formations of altered minerals were discussed here. By the ASD, the spectral curve of different geological units in the Jintanzi and Fangshankou gold deposits were analysed and summarized. The results show that the sericite and limonite are mainly related with the gold mineralization and widely occurred in the gold deposits. Therefore, we proposed that the sericite and limonite are the iconic alteration mineral assemblages for gold mineralization and the models of altered minerals for gold deposits could be established in this region.

  15. Genesis of the hydrothermal gold deposits in the Canan area, Lepaguare District, Honduras

    Science.gov (United States)

    Mattioli, Michele; Menichetti, Marco; Renzulli, Alberto; Toscani, Lorenzo; Salvioli-Mariani, Emma; Suarez, Pedro; Murroni, Alessandro

    2014-04-01

    The Canan area (Honduras) is characterized by a gold-bearing ore deposit that is associated with quartz-veined shear zones. Gold mineralization occurs in low-to medium-grade metamorphic host-rocks (graphitic and sericitic schists). Hydrothermal fluids, which are associated with the emplacement of Cretaceous-Tertiary granodioritic intrusions, are responsible for the formation of quartz veins and the hydrothermal alteration of wall-rocks. Three main altered zones have been detected in the wall-rocks as far as 150 cm from the quartz veins. The distal zone (up to 50-cm thick) contains quartz, chlorite and illite. The intermediate zone is the thickest (up to 80 cm) and is marked by quartz, muscovite, sulphides, kaolinite and native elements such as Au and Ag. The proximal zone, which is close to the quartz veins, is rather thin (up to 25 cm) and contains clay minerals, Al-oxides-hydroxides and sulphides. The transition from the distal to the proximal zone is accompanied by the enrichment of SiO2 and the depletion of all other major elements, except for Fe2O3(tot). Precious metals occur in the highest concentrations in the intermediate zone (Au up to 7.6 ppm and Ag up to 11 ppm). We suggest that gold was transported as a reduced sulphur complex and was precipitated from the hydrothermal solution by the reaction of the sulphur complexes with Fe2+ from the alteration of the mafic minerals of the host-rock. Fluid-wall-rock interactions seem to be the main cause of gold mineralization. Genetic relationships with a strike-slip fault system, hydrothermal alteration zones within the metamorphic wall-rocks, and an entire set of geochemical anomalies are consistent with orogenic-type gold deposits of the epizonal class.

  16. Gold upgrading in metamorphosed massive sulfide ore deposits: Direct evidence from laser-ablation-inductively coupled plasma-mass spectrometry analysis of invisible gold

    Science.gov (United States)

    Wagner, Thomas; Klemd, Reiner; Wenzel, Thomas; Mattsson, Benny

    2007-09-01

    The metamorphosed Boliden volcanic-hosted massive sulfide (VHMS) ore deposit, northern Sweden, is characterized by an abundance of massive arsenopyrite ore and unusually high gold enrichments (up to 300-600 g/t) in crosscutting veins and fracture zones. The ore textures observed record progressive recrystallization and porphyroblast growth during meta morphism. We conducted a systematic laser-ablation-inductively coupled plasma-mass spectrom etry (LA-ICP-MS) study on the gold distribution in fine-grained massive arseno-pyrite and pyrite ore, partially recrystallized arsenopyrite ore, and both arsenopyrite and pyrite porphyroblasts found in gold-rich veins. The gold concentrations in massive arseno-pyrite are highest (30-50 ppm on average) and systematically decrease to 0-2.7 ppm with increasing degree of recrystallization. By contrast, gold concentrations in pyrite ore are much lower and do not exceed 0.2 ppm. The LA-ICP-MS data, coupled with textural data, provide the first direct conclusive evidence that gold is progressively liberated from massive sulfide ores during metamorphism and reprecipitated in veins and other low-strain sites. We suggest that such upgrading is the principal mechanism responsible for significant gold enrichment observed in many metamorphosed VHMS deposits worldwide.

  17. Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang:A Case Study on the Aketishikan Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    YUAN Feng; ZHOU Taofa; TAN Lugui; LUO Xianrong; YUE Shucang

    2004-01-01

    Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.

  18. 3D Modeling from Induced Polarization Method for Identification of Gold Deposit Exploration in North Minahasa, North Sulawesi, Indonesia

    Science.gov (United States)

    Faruqi, I. H.; Alfadli, M. K.; Asyari, A.; Wijaksana, A.

    2016-12-01

    According to North Sulawesi's Mining Agency and Ministry of Energy and Mineral Resources, North Minahasa Regency have at the very least 14 Million Tons of gold deposit resource. The research area was conducted in Tatelu District, North Minahasa Regency within an extensive area of 700m2. Geologically, the research area is in gold mineralization zone that have already been mined by both local people or legal mining company. This area is composed from quarter volcanic rocks such as lava, lapili, and ash as a results from Klabat Volcano's eruption. This research was conducted in order to know the distribution of gold mineralisation in low-sulphidation ephitermal environment up until 75 meter beneath the ground. The approach in this research is using Induced Polarization (IP) in five measurement line with each length of the measurement line is 700m. Mineralization zone could be detected by IP shown by the chargebility value >280ms. IP method could detect gold deposit near the surface. Meanwhile, the value of resistivity anomaly reach >300 ohm.m indicating rocks with low porosity like igneous rocks and lava. Following that, the integration of both IP and Resistivity data is used to make a 3D model of gold mineralization zone that can estimate the distribution of gold mineralization underground by detecting gold's gangue mineral. The zonation that has been done can be one of the basic method for the identification of gold deposit exploration and with the construction of this model, the success ratio of gold deposit exploration are expected to rise higher. Keywords: 3D Modeling, Induced Polarization, Resistivity, Gold Deposit

  19. Genesis and Geological—Geochemical Characters of the ushan Gold Deposit,Shandong,China

    Institute of Scientific and Technical Information of China (English)

    翟建平; 胡凯; 等

    1996-01-01

    The Rushan gold deposit,explored in recent years in the Jiaodong area,Shandong Provinces,is a quartz vein-type gold deposit hosted in granite.The temperature of its major mineralization episode is between 220℃ and 280℃.The salinity o the ore-forming fluid is 5% to 9% NaCl equivalent,with H2O and CO2 as he dominant gas constituents.The fluid is rich in Na+,Ca2+ and Cl-,but relatively impoverished in K+ and F-,characterized by either Ca2+>Na+>K+(in three samples)or Na+>Ca+>K+(in six samples).Hydrogen and oxygen isotopes in the ore-forming fluid are highyly variable with δ18OH2o ranging between-7.70‰and 5.97‰andδDH2 o between-128‰and-71‰.The possiblity of lamprophyre serving as the source of gold can be excluded in view of its low gold content on the order of 2.5×10-9,Rb-S isochron ages of the deposit and the host Kunyushan granite are(104.8±1.5)Ma and 134.6Ma respectively with the respective initial Sr ratios of 0.71307 and 0.7096.It is considered that the emplacement of the labprophyre under a tensile environment had provided sufficient heat energy to facilitate deep circulation of meteoric water by which ore metals were extracted from the Kunyushan granite through long-term water-rock reaction.

  20. The conjunction of factors that lead to formation of giant gold provinces and deposits in non-arc settings

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; Richard J. Goldfarb; M. Santosh

    2016-01-01

    It is quite evident that it is not anomalous metal transport, nor unique depositional conditions, nor any single factor at the deposit scale, that dictates whether a mineral deposit becomes a giant or not. A hierarchical approach thus is required to progressively examine controlling parameters at successively decreasing scales in the total mineral system to understand the location of giant gold deposits in non-arc environments. For giant orogenic, intrusion-related gold systems (IRGS) and Carlin-type gold deposits and iron oxide-copper-gold (IOCG) deposits, there are common factors among all of these at the litho-spheric to crustal scale. All are sited in giant gold provinces controlled by complex fundamental fault or shear zones that follow craton margins or, in the case of most Phanerozoic orogenic giants, define the primary suture zones between tectonic terranes. Giant provinces of IRGS, IOCG, and Carlin-type deposits require melting of metasomatized lithosphere beneath craton margins with ascent of hybrid lamp-rophyric to granitic magmas and associated heat flux to generate the giant province. The IRGS and IOCG deposits require direct exsolution of volatile-rich magmatic-hydrothermal fluids, whereas the associa-tion of such melts with Carlin-type ores is more indirect and enigmatic. Giant orogenic gold provinces show no direct relationship to such magmatism, forming from metamorphic fluids, but show an indirect relationship to lamprophyres that reflect the mantle connectivity of controlling first-order structures. In contrast to their province scale similarities, the different giant gold deposit styles show contrasting critical controls at the district to deposit scale. For orogenic gold deposits, the giants appear to have formed by conjunction of a greater number of parameters to those that control smaller deposits, with resultant geometrical and lithostratigraphic complexity as a guide to their location. There are few giant IRGS due to their inferior fluid

  1. Tourmaline from the Archean G.R.Halli gold deposit, Chitradurga greenstone belt, Dharwar craton (India): Implications for the gold metallogeny

    OpenAIRE

    Susmita Gupta; Jayananda, M.; Fareeduddin

    2014-01-01

    Tourmaline occurs as a minor but important mineral in the alteration zone of the Archean orogenic gold deposit of Guddadarangavanahalli (G.R.Halli) in the Chitradurga greenstone belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli gold deposit as (a) clusters of very fine grained aggregates which form a minor constituent in the matrix of the altered metabasalt (AMB tourmaline) and (b) in quartz-carbonate veins (vein tourmaline). The vein...

  2. REE geochemistry of auriferous quartz carbonate veins of Neoarchean Ajjanahalli gold deposit, Chitradurga schist belt, Dharwar Craton, India

    Directory of Open Access Journals (Sweden)

    S. Sarangi

    2013-03-01

    Full Text Available REE composition of the carbonates of the auriferous quartz carbonate veins (QCVs of the Neoarchean Ajjanahalli gold deposit, Chitradurga schist belt, Dharwar Craton, is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly. As positive Eu anomaly is associated with low oxygen fugacity, we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid. The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir. The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.

  3. Pb Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongying; LIANG Yibo

    2002-01-01

    There are two types of gold ore in Shibaqinghao gold deposit, a mylonite ore and a quartz - vein ore. Pb isotope compositions for mylonite ore are characterized by lower Pb isotope ratios ranging from 16.63 to 17.45 (206Pb/204Pb), 15.31 to15.48 (207Pb/204pb), 36.52 to 38.85 (208Pb/204Pb). They are scattered very close to a model curve of the mantle evolution. These ratios suggest that gold in the mylonite ore might be derived from the country rocks, which originated directly in the upper mantle. Pb isotope compositions for quartz - vein ore are characterized by higher Pb isotope ratios ranging from 18.23 to 19.74 (206Pb/204Pb), 15.69 to 15.89 (207Pb/204Pb), 38.64 to 40. 13 (208Pb/204Pb). They are scattered very close to a model curve of the upper crustal evolution. These facts indicate that the gold in the quartz - vein ore might be related to some granitic magma generated in the crust.

  4. Typomorpic Characteristics of the Major Minerals in the Puziwan Gold Deposit, Datong, Shanxi, China

    Institute of Scientific and Technical Information of China (English)

    QING Min; NIU Cuiyi; LEI Shibin

    2008-01-01

    Utilizing theories of minerageny and prospecting mineralogy, the authors studied theattitude, morphotype and chemical composition of metallic minerals of pyrite, gold, chalcopyrite,galena and sphalerite, non-metallic minerals of quartz, carbonate, dolomite and rutile in the Puziwangold deposit. The study shows the following results. (1) The mineral assemblage is complex and thespecies of sulfide are abundant with occurrences of sulfosalt minerals. (2) The composition in theminerals is complex and there rich micro elements, including As, Sb, Bi, Se, Te, Au, Ag, Cu, Pb, Zn, andCr, Ni, V. The typomorphic characteristics of the association of the elements and their specific valuesuggest that gold mineralization is associated with shallow magmatic hydrothermai activity, the ore-forming fluid is the mixture of abundant rising alkali magmatic water originating from the mantle orthe lower crust and the descending acid atmospheric water. (3) Ankerite, Fe-rich sphalerite, granularTi-rich rutile are widely distributed, which indicate great denudation depths, high mineralizationtemperature. The deposit is found in the middle and shallow positions of the porphyry series. The deeplayers are not favorable for gold mineralization. (4) Copper minerals are rich in the ores and sulfideshave high content of copper, suggesting possible porphyry-type Cu (Au) mineralization in deeppositions and the surrounding areas.

  5. Dating and Fluid Geochemistry of the Sarkobu Gold Deposit in Altay, Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    DING Rufu; WANG Jingbin; ZHAO Lunshan; MA Zhongmei; ZHANG Jinhong

    2004-01-01

    The dating of fluid inclusions of quartz yields an Ar-Ar isochrone age of 320.4±6 Ma. Three types of fluid inclusions have been identified with the homogenization temperature ranging from 157℃ to 362℃. The homogenization temperature consists of two groups. The first group varies from 157℃ to 166℃, and the second from 232℃ to 362℃.Their chemical composition is dominated by Na+-Ca2+-Mg2+ and Cl-. The relative concentration of ions is characteristic by Na+>Ca2+>K+>Mg2+ and C1->SO42-> F-. The δD and δ180 values indicate that the ore-forming fluid originates from mixing of multi-source water. The Sarkobu gold deposit has experienced two mineralization stages: gold was enriched during the volcanic-exhalative-sedimentary process in the early stage, while the gold deposit was finally formed under compression-shearing during the orogenic period.

  6. Ore-forming fluids in the Dongping gold deposit, northwestern Hebei Province

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Dongping gold deposit is contained within an inner contacting zone of the Hercynian Shuiquangou alkali syenite. The ores occur as veins or as replacement bodies. Fluid inclusion observation shows that in early and main mineralizing stages inclusion types are gas and gas-liquid inclusions, respectively. Gas inclusions occur in isolation in vein quartz, their homogenization tem-perature is 372-306℃, and salinity 3.7-1.0 wt% NaCl. Gas-liquid inclusions occur in clusters or healed fractures but do not cut quartz boundary with homogenization temperature 342-267℃ and salinity 1.9-0.8 wt% NaCl. Stable isotope measurements show that at main gold mineralization, hydrogen and oxygen isotopic ratios of the mineralizing fluids are -70.8‰- -108.4‰ and 2.44‰-4.05‰, respectively. Primary ore fluids in Dongping are higher temperature and lower salinity NaCl-CO2-H2O fluids, and come from Yanshanian granitic magmatism. Fluid immiscibility, fluid-rock interactions and meteoric water adding were main reasons for gold deposition.

  7. Large clusters of gold deposits and large-scale metallogene-sis in the Jiaodong Peninsula, Eastern China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Jiaodong Peninsula is the largest repository of gold in China based on the production in history. It covers less than 0.2% of China's territory, but production of gold accounts for about one fourth of the whole country. Thus, the Jiaodong Peninsula is a typical area or case of large-scale metallogenesis and a large clusters of mineral deposits in China. It is characterized by the large clusters of gold deposits in large scale, high reserve and short mineralizing stage. In this study, we suggest that the eastern boundary of the large clusters of gold deposits is as same as that of North China Block, the gold deposits are hosted by Archean metamorphic rocks or Mesozoic granites, and the age of gold mineralization is 121.6 to 122.7 Ma. Gold and related ore-forming materials are derived from multisources, i.e. Archean metamorphic rocks, granites and intermediate-mafic dikes, especially, intermediate-mafic dikes and calc-alkaline granites. The metallogenic geodynamic process is constrained by the tectonic evolution of eastern North China Block during Late Mesozoic, and it is the result of the interaction between mantle and crust as the boundary plates are playing role on the block.

  8. Brazil's premier gold province. Part II: geology and genesis of gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero

    Science.gov (United States)

    Lobato, Lydia; Ribeiro-Rodrigues, Luiz; Vieira, Frederico

    2001-07-01

    Orogenic, gold deposits are hosted by rocks of the Archean Rio das Velhas greenstone belt in the Quadrilátero Ferrífero region, Minas Gerais state, Brazil, one of the major gold provinces in the world. The gold deposits occur at the base of the mafic-ultramafic succession, with the most important orebodies controlled by E-W-striking, strike-slip faults. The main mineralization styles are (1) structurally controlled, sulfide replacement zones in banded iron formation (BIF); (2) disseminated sulfide minerals and gold in hydrothermally altered rocks along shear zones; and (3) auriferous quartz-carbonate-sulfide veins and veinlets in mafic, ultramafic, and felsic volcanic rocks, and also in clastic sedimentary rocks. The most common host rocks for ore are metamorphosed oxide- and carbonate-facies banded iron (± iron-rich metachert) formations (e.g., the Cuiabá, São Bento and Raposos deposits) and the lapa seca unit, which is a local term for intensely carbonatized rock (e.g., the giant Morro Velho mine with >450 t of contained gold). Metabasalts host most of the remaining gold deposits. Mineralogical characteristics and fluid inclusion studies suggest variations in the H2O/CO2 ratio of a low-salinity, near-neutral, reducing, sulfur-bearing, ore fluid. The presence of abundant CH4-rich inclusions is related to reduction of the original H2O-CO2 fluid via interaction with carbonaceous matter in the wallrocks. Oxygen fugacity was close to that of graphite saturation, with variations likely to have been influenced by reaction with the carbonaceous matter. Carbon-rich phyllites and schists, which commonly bound ore-bearing horizons, seem to have played both a physical and chemical role in localizing hydrothermal mineral deposition. Microtextural studies indicate that gold deposition was mainly related to desulfidation reactions, and was paragenetically coeval with precipitation of arsenic-rich iron sulfide minerals. Carbon isotope data are compatible with dissolution of

  9. Periodic nanotemplating by selective deposition of electroless gold island films on particle-lithographed dimethyldichlorosilane layers.

    Science.gov (United States)

    Ahn, Wonmi; Roper, D Keith

    2010-07-27

    Uniform hexagonal arrays of diverse nanotemplated metal structures were formed via selective electroless gold plating on particle-lithographed dimethyldichlorosilane layers. Surface-associated water at silica bead interstices was shown to correlate with the formation of silane rings with outer ring diameters ranging from 522.5+/-29.7 to 1116.9+/-52.6 nm and/or spherical gold nanoparticles with diameters from 145.5+/-20.2 to 389.1+/-51.1 nm in the array. Reproducibility and millimeter-size scalability of the array were achieved without the need for expensive and sophisticated lithography or metal deposition equipment. The formation of each structure was explained on the basis of the silanization mechanism and microscopic characterization, as well as dimensional analysis of the nanostructures. This new, facile, and versatile method enables fine fabrication of regular metal nanoparticle array platforms to improve optical and plasmonic features in nanoelectronics and nanophotonic devices.

  10. Gold deposits in the late Archaean Nzega-Igunga greenstone belt, central plateau of tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Feiss, P.G.; Siyomana, S.

    1985-01-01

    2.2 m oz of gold have been produced, since 1935, from late Archaean (2480-2740 Ma) greenstone belts of the Central Plateau, Tanzania. North and east of Nzega (4/sup 0/12'S, 3/sup 0/11'E), 18% of the exposed basement, mainly Dodoman schists and granites, consists of metavolcanics and metasediments of the Nyanzian and Kavirondian Series. Four styles of mineralization are observed. 1. Stratabound quartz-gold veins with minor sulfides. Host rocks are quartz porphyry, banded iron formation (BIF), magnetite quartzite, and dense, cherty jasperite at the Sekenke and Canuck mines. The Canuck veins are on strike from BIF's in quartz-eye porphyry of the Igusule Hills. 2. Stratabound, disseminated gold in coarse-grained, crowded feldspar porphyry with lithic fragments and minor pyrite. At Bulangamilwa, the porphyry is conformable with Nyanzian-aged submarine (.) greenstone, volcanic sediment, felsic volcanics, and sericite phyllite. The deposits are on strike with BIF of the Wella Hills, which contains massive sulfide with up to 15% Pb+Zn. 3. Disseminated gold in quartz-albite metasomes in Nyanzian greenstones. At Kirondatal, alteration is associated with alaskites and feldspar porphyry dikes traceable several hundred meters into post-Dodoman diorite porphyry. Gold is with pyrite, arsenopyrite, pyrrhotite, minor chalcopyrite, and sphalerite as well as tourmalinite and silica-cemented breccias. 4. Basal Kavirondian placers in metaconglomerates containing cobbles and boulders of Dodoman and Nyanzian rocks several hundred meters up-section from the stratabound, disseminated mineralization at Bulangamilwa.

  11. Microorganisms in Lianxian lateritic gold deposit in Guangdong and their effects on leaching of heavy metals

    Institute of Scientific and Technical Information of China (English)

    CHEN Binghui; LIU Huhu; WU Fuhai; XU Wenlie

    2005-01-01

    Microorganisms in the lateritic profiles of the Lianxian gold deposit in Guangdong were cultured, isolated and identified. The microorganisms include bacteria such as Bacillus, Enterobacter, Pseudomonas, Lactobacillus, Actinetobacter, Aeromona, Listeria, Agrobacterium, Corynebacterium, and Moraxella, fungi such as Penicillium, Alternaria, Cladosporium, Saccharcomyces, Mucor, and the chemoautotrophic Thiobacillus. It is shown in a leaching experiment that the microorganisms can accelerate the leaching of Cu, Cd, Zn, and that the G - bacteria are most efficient for leaching Cu, Zn and the G + bacteria are better for leaching Cd.

  12. Decrepitation Thermometry and Compositions of Fluid Inclusions of the Damoqujia Gold Deposit,Jiaodong Gold Province,China:Implications for Metallogeny and Exploration

    Institute of Scientific and Technical Information of China (English)

    Yang Liqiang; Deng Jun; Zhang Jing; Guo Chunying; Gao Bangfei; Gong Qingjie; Wang Qingfei; Jiang Shaoqing; Yu Haijun

    2008-01-01

    The recently discovered Damoqujia (大磨曲家) gold deposit is a large shear zone-hosted gold deposit of disseminated sulphides located in the north of the Zhaoping (招平) fault zone, Jiaodong (胶东) gold province, China. In order to distinguish the temperature range of cluster inclusions from different mineralization stages and measure their compositions, 16 fluid inclusions and 5 isotopic geochemistry samples were collected for this study. Corresponding to different mineralization stages, the multirange peaks of quartz decrepitation temperature (250-270, 310-360 and 380-430℃(2) indicate that the activity of ore-forming fluids is characterized by multistage. The ore-forming fluids were predominantly of high-temperature fluid system (HTFS) by CO2-rich, and SO2-4-K+ type magmatic fluid during the early stage of mineralization and were subsequently affected by low-temperature fluid system (LTFS) of CH4-rich, and Cl--Na+/Ca2+ type meteoric fluid during the late stage of mineralization. Gold is transferred by Au-HS- complex in the HTFS, and Au-Cl- complex can be more important in the LTFS. The transition of fluids from deeper to shallow environments results in mixing between the HTFS and LTFS, which might be one of the most key reasons for gold precipitation and large-scale mineralization. The ore-forming fluids are characterized by high-temperature, strong-activity, and superimposed mineralization, so that there is a great probability of forming large and rich ore deposit in the Damoqujia gold deposit. The main bodies are preserved and extend toward deeper parts, thereby suggesting a great potential in future.

  13. The Wassa deposit: A poly-deformed orogenic gold system in southwest Ghana - Implications for regional exploration

    Science.gov (United States)

    Perrouty, Stéphane; Jessell, Mark W.; Bourassa, Yan; Miller, John; Apau, Daniel; Siebenaller, Luc; Velásquez, Germán; Baratoux, Lenka; Aillères, Laurent; Béziat, Didier; Salvi, Stefano

    2015-12-01

    The Ashanti greenstone belt in southwest Ghana hosts many gold deposits distinguished by different timing and structural contexts. This study investigates the evolution of the Wassa system by integrating field and geophysical observations. This 4 million ounces (past production and current resources) gold deposit is interpreted to represent the oldest gold mineralization event in West Africa with gold-bearing pyrites aligned and stretched within the S1 ductile fabric. Mineralized quartz-carbonate veins were strongly deformed during the D1 deformation event. Three additional folding events are characterized by hectometer-scale tight to isoclinal folds, by a kilometer-scale synform fold centered on the mine and by a late recumbent metric-scale folds. Because of its early timing, the Wassa system represents a new poly-deformed deposit type in West Africa and highlights a potential for new discoveries in the underexplored meta-volcanic and meta-sedimentary Sefwi Group. Timing of the gold mineralization at the Wassa mine makes this deposit type a possible candidate for the source of the gold contained in the Tarkwa paleoplacer.

  14. Geochemical Characteristics and Geological Significance of the Tawangshan gold deposit in Dongfang City, Hainan Province

    Directory of Open Access Journals (Sweden)

    Xiong Ying

    2016-01-01

    Full Text Available The Tawangshan gold deposit is located in the southwest of the Gezhen ductile shear zone in southwestern Hainan Island. Major, trace and rare earth element characteristics of the least altered granites and altered granite ores, as well as the oxygen and hydrogen isotopic features of the quartz, the sulfur and lead isotopic features of the pyrites, galena from this deposit were systematically studied. The altered granite ores content of Fe2O3/(Fe2O3+FeO ranges from 0.409 to 0.410, showing strong magma reducibility. REE characteristics of the granite ores are similar to those of the least altered granites, indicating a close relationship between the mineralization and granite. Hydrogen and oxygen analysis results show that the content of 18OSMOW ranges from 7.7‰ to 16.3‰, δ18OH2O ranges from 1.0‰ to 6.8‰, suggesting that the ore-forming fluid was the dual nature of the metamorphic and magmatic hydrothermal. The compositions of sulfur isotope and lead isotope imply that the metallogenic materials of the deposit derived from the deep magma mixing with the shell source material contamination. Ore deposit geological features reflect the obvious characteristics of magmatic hydrothermal and porphyritic granite is mineralized rocks, implying the deposit was formed in the post-collisional extensional tectonic setting.

  15. Silver or gold deposition onto magnetite nanoparticles by using plant extracts as reducing and stabilizing agents.

    Science.gov (United States)

    Norouz Dizaji, Araz; Yilmaz, Mehmet; Piskin, Erhan

    2016-06-01

    In this paper, we describe an environmentally friendly procedure to produce silver (Ag) or gold (Au)-deposited magnetite nanoparticles by using plant extracts (Ligustrum vulgare) as reducing and stabilizing agents. Firstly, magnetite nanoparticles (∼6 nm) with superparamagnetic properties - SPIONs - were synthesized by co-precipitation of Fe(+ 2) and Fe(+ 3) ions. Color changes indicated the differing amounts of Au and Ag ions reduced and deposited on to the SPIONs when the plant extracts were used. UV-vis and transmission electron microscope (TEM) with energy dispersive X-ray (EDX) apparatus confirmed the metallic deposition. Magnetic saturation decreased when the amount of the metallic deposition increased, which was measured by vibrating sample magnetometry (VSM). Due to the molecules coming into contact with - and even remaining on - the surface of the nanoparticles after aggressive washing procedures, the Ag/Au-deposited SPIONs were stable, and almost no agglomeration was observed for months. Fourier Transform Infrared (FTIR) spectra depicted that functional groups such as carboxylic and ketone groups, which are most probably responsible for the reduction and stabilization of Ag/Au- carrying magnetite nanoparticles, originated from the plant extract. The proposed route was facile, viable, and reproducible, and it should be stressed that nanoparticles do contain only safe biomolecules as stabilizing agents on their surfaces.

  16. Geological-Geochemical Characteristics of Carlin- and Carlin-Like-Type Gold Deposits in South Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    张复新; 张静

    2003-01-01

    In this paper an integrated geological and geochemical comparison is made of Carlin-type and Carlin-like-type gold deposits in the region of South Qinling with their associated hydro-thermal sedimentary lead-zinc deposits, the Carlin-type deposits in the Yunnan-Guizhou-Guan-gxi gold triangle, China, the Carlin gold deposits, Carlin, western United States, and the Mu-runtau-type gold deposits in Uzbekistan. The comparative study indicates that the formation ofthese deposits has an intimate coupling relation with the mechanism of the tectonic movement ofmodern plates. Therefore, these deposits belong to those that were formed in the orogenic stage.They have the following similar characteristics: they are all sediment-hosted, occur in a tectonicenvironment of extensional rifting nature and show the characteristics of syngenetically modifiedmineralization. On the other hand, they also have noticeable differences: they are different inrespect to their tectonic settings, association and structure of orogenic belts and complexity andstrength of the modified mineralization. The regional tectonic evolution and extensive mineraliza-tion in orogenic belts are different expressions of the same continental dynamic process.

  17. Third-order nonlinear optical response of colloidal gold nanoparticles prepared by sputtering deposition

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Hemerson P. S.; Alencar, Márcio A. R. C.; Hickmann, Jandir M. [Optics and Materials Group–OPTMA, Universidade Federal de Alagoas, CAIXA POSTAL 2051, 57061-970 Maceió (Brazil); Wender, Heberton [Brazilian Synchrotron National Laboratory (LNLS), CNPEM, Rua Giuseppe Máximo Scolfaro 10.000, 13083-970 Campinas (Brazil); Department of Physics, Universidade Federal do Mato Grosso do Sul, 79070-900, Campo Grande (Brazil); Teixeira, Sergio R. [Institute of Physics, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil); Dupont, Jairton [Laboratory of Molecular Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil)

    2013-11-14

    The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced by sputtering deposition were investigated, using the thermally managed Z-scan technique. Particles with spherical shape and 2.6 nm of average diameter were obtained and characterized by transmission electron microscopy and small angle X-ray scattering. This colloid was highly stable, without the presence of chemical impurities, neither stabilizers. It was observed that this system presents a large refractive third-order nonlinear response and a negligible nonlinear absorption. Moreover, the evaluation of the all-optical switching figures of merit demonstrated that the colloidal nanoparticles prepared by sputtering deposition have a good potential for the development of ultrafast photonic devices.

  18. Fluid Inclusions and Daughter Minerals of Taibai Gold Deposit, ShaanXi Province, China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A discovery of daughter minerals in fluid inclusions of Taibai gold deposit, Shaanxi province has been focused on, which is a unique breccia-cemented gold-bearing system. The breccia zone strikes NWW-SEE, occurring in Devonian strata of Southern Qinling Mountains. The cement is mainly composed of ankerite, pyrite, calcite and quartz, which may be divided into four main tectonic-mineralizing stages. Gold mainly occurs in pyrite and ankerite of stage II and IV. It is found that three types of fluid inclusions can be distinguished: (1) aqueous inclusions (type B); (2) CO2-rich inclusions (type C); (3) daughter minerals-containing inclusions (type A). LRM (Laser Raman Micro-probe) analyses shows that the content of CO2 occupies 54.4-70.7% (mole fraction, so as the follows) in vapor phases of different type fluid inclusions. CH4 (5.2%-7.3%) and H2S (6.0%-12.7%) exist in both vapor and liquid phases. Many daughter minerals in fluid inclusions of ankerite and quartz have been found. Several kinds of daughter minerals, including ankerite, pyrite, arsenopyrite and halite, were determined by using SEM (scanning electron microscope) / EDS (energy dispersive spectrometer) technique. EPMA (electron probe micro-analysis) technique was also applied to study the daughter minerals exposed to the surface of polis hed thin sections.

  19. Manufacturing of nanoscale thickness gold lines by laser curing of a discretely deposited nanoparticle suspension

    Science.gov (United States)

    Bieri, N. R.; Chung, J.; Poulikakos, D.; Grigoropoulos, C. P.

    2004-03-01

    The present work is focused on a novel method for the manufacturing of electric microconductors for semiconductors and other devices. Three different technologies are combined in this technique: controlled (drop on demand) printing, laser curing, and the employment of nanoparticles of matter, possessing markedly different properties (here, melting point) than their bulk counterparts. A modified on demand ink jet process is utilized to print electrically conducting line patterns from a suspension of gold nanoparticles in toluene. Microdroplets of 60-100 μm diameter are generated and deposited on a moving substrate such that the droplets form continuous lines. Focused laser irradiation is utilized in order to evaporate the solvent, melt the metal nanoparticles in the suspension, and sinter the suspended particles to form continuous, electrically conducting gold microlines on a substrate. The ultrafine particles in the suspension have a diameter size range of 2-5 nm. Due to curvature and surface effects of such small particles, the melting point is markedly lower than that of bulk gold (1063 ∘C). Atomic force microscopy and scanning electron microscopy have been employed to investigate the topology of the cured line. In situ visualization of the curing process has been conducted. Results on the effect of the laser irradiation power on the topology and width of the cured line, which is directly related to the electrical conductivity, are reported.

  20. Organic Geochemistry of Sedimentary Rock-hosted Disseminated Gold Deposits in Southwestern Guizhou Province,China

    Institute of Scientific and Technical Information of China (English)

    BAO Zhiwei; ZHAO Zhenhua; Jayanta GUHA

    2005-01-01

    Sedimentary rock-hosted disseminated gold (SRHDG) deposits in the Youjiang-Nanpanjiang Basin,southwestern Guizhou Province are commonly hosted by the same fold crests that commonly contain a remarkable amount of organic material. The total organic carbon (TOC) contents of the ores and host rocks are usually less than 1%. The reflectance of vitrinite and pyrobitumen in the ores and the host rocks ranges from 1.5% to 4.5%, often in the range of 2% to 3%. In the Lannigou deposit, the reflectance of vitrinite and pyrobitumen in the ores is usually somewhat higher than those within the host rocks, indicating a hydrothermal impact on the organic matter in the altered host rocks. On the contrary, the estimated maximum paleotemperatures of the Getang and Zimudang deposits are higher than the homogenization temperatures of the fluid inclusions in the ores, signifying that the organic matter maturation predated Au mineralization. No correlation between the organic matter contents and Au concentrations were recognized in the ores.However, the most striking observation is that there is a positive correlation between the S2 (a parameter of Rock-Eval analysis), Au and As contents of the ores in the Lannigou deposit. Organic matter maturation and migration is apparent from the TOC vs. HCI diagram. Furthermore, group analysis of the dichloromethane extractable organic component of the ores and host rocks shows that the maturation degree of the organic matter in the ores is slightly higher than that of the host rocks in the Lannigou gold deposit. However, the compositions of their alkanes, steranes and terpenes, which serve as biomarkers, are quite similar; this suggests that the organic matter found in the ores and host rocks has a common marine source. Organic matter probably contributed to the preconcentration of Au in the host rocks. Hydrocarbons in the system,on the other hand, clearly contributed to the emplacement of the gold mineralization through thermal sulfate reduction

  1. Mineralogy of Copper-Gold Deposit, Masjid Daghi Area, Jolfa, IRAN

    Science.gov (United States)

    Zenoozi, Roya

    2010-05-01

    The Copper-Gold deposit of Masjid Daghi area is located in the Jolfa quadrangle (scale 1:100,000), East Azerbaijan Province, north-west Iran. The deposit, hosting by sub-volcanic bodies comprise of quartz monzonite composition whose intruded the Tertiary volcanic and volcanic-sedimentary rocks and turbidities. The Tertiary volcanic rocks consist of andesite, trachy andesite and quartz andesite. These mineral-bearing bodies related to Late Eocene sub-volcanic activities which intrudded the Eocene volcanic rocks. Mineralography, XRD and SEM studies showed that the variations in mineralization of the area. The main agent of mineralization is the intrusion of Late Eocene sub volcanic bodies inside the Tertiary volcanic units. The mineralography studies revealed two main groups of mineralization as oxides and sulfides. The sulfide minerals formed as veins, vein lets and stock work.The economic minerals comprise of native gold, copper sulfides. The native gold occurring in siliceous veins and almost as inclusions inside the sulfides minerals such as chalcopyrite. The copper sulfides, contain pyrite, chalcopyrite and chalco-pyrrhoyite. Pyrite is main sulfide in the area and formed as disseminations, cavity filling and colloform. The amount of pyrite, chalcopyrite and chalco-pyrrhoyite increases with depth. Supergene alteration produced digenite, covellite, bornite, and malachite. The alteration occurred as potassic, phyllic, argillic and propylitic minerals. Furthermore, selective sercitic, sericitic-chloritic and alunitic alterations are seen around the mineralized veins. The mineralography studies indicate that pyrite is main mineral phase and native gold occurred in silicious vein almost as inclusions inside the sulfide mineral. Most of economic mineral formed as veins, vein lets, disseminated, cavity filling and colloform which related to intrusions of Late Eocene quartz monzonite bodies into the Eocene volcanic rocks and turbiditse. Some types of alterations such as

  2. Significance of zircon trace element geochemistry, the Shihu gold deposit,western Hebei Province, North China

    Institute of Scientific and Technical Information of China (English)

    CAO Ye; LI Shengrong; ZHANG Huafeng; LIU Xiaobin; LI Zhenzhen; AO Chong; YAO Meijuan

    2011-01-01

    The Shihu gold deposit is characterized by gold-bearing quartz-polymetallic sulfides and quartz veins. Both Mapeng granitoids batholith and intermediate-basic dikes intruded the metamorphic basement rocks, and are spatially associated with gold mineralization. Trace element abundances in zircons from the Shihu gold deposit, determined by laser-ablation microprobe ICPMS analysis, are sensitive to source rock type and crystallization environment. Concentrations of 21 trace elements were determined for zircons from granitoid rocks, diorites,quartz diorite porphyrites and gold-bearing quartz veins revealed some elemental characteristics and chondrite-normalized trace element patterns from different samples. There were no distinctive differences in REE concentrations of zircons from plutonic rocks and quartz veins, indicating that they probably had the same origin. Relatively flat chondrite-normalized REE patterns with (Yb/Sm)N ratios less than 60 characterized zircons from quartz diorite porphyrites and quartz veins. The highest Nb/Ta ratios were found in zircons from quartz diorite porphyrites, whereas the lowest ratios were found in quartz vein zircons. The Nb/Ta ratios were broadly correlated with HREE+Y contents, and had weak positive correlations with the depth of the Eu negative anomalies. High values U up to 0.4% and Th up to 0.1%, as well as positive correlations with REE+Y characterized zircons from quartz vein. The lowest Th/U ratios of zircons present in quartz veins reflected the relatively high concentration of U in hydrothermal fluid, and high Pb concentrations only typified quartz vein grains relatively enriched in U and Th.Zircons from quartz diorite porphyrites showed the most pronounced Ce anomalies, whereas weak Ce anomalies were typical of zircons from quartz veins, in which Eu/Eu* of zircons had a broadly negative correlation with Ce/Ce*. Trace element geochemistry of zircons from mineralized quartz veins and plutonic rocks confirmed that the

  3. The Berezitovoe gold-polymetallic deposit (Upper Amur region, Russia: Structure, mineralogy and genetic aspects

    Directory of Open Access Journals (Sweden)

    Alexandr S. Vakh

    2016-05-01

    Full Text Available The Berezitovoe deposit in the Sergachi volcano-plutonic and metallogenic belt preserves evidence for polymetallic mineralization of multiple stages. The steeply dipping garnet-tourmaline-muscovite-quartz metasomatites (with K-Ar ages of 132 ± 2.9 and 127 ± 4.4 Ma carry two distinct stages of mineralization developed at different times: (1 polymetallic mineralization and (2 gold-quartz. The deposit is located within Paleozoic gneissose granitoids of the Pikansky complex (dated as 379 ± 1.1 Ma by zircon U-Pb method intruded by early Cretaceous porphyry-like granites of the Haikta pluton (dated as 137 ± 0.67 Ma by zircon U-Pb method and late Cretaceous dikes of porphyrites, porphyries, and lamprophyres. Evidence suggests the action of late gold-bearing hydrothermal fluids on the early polymetallic ores and the selective mobilization of some elements from these lead to redeposition together with complex sulphosalts.

  4. Geochemical Characteristics and Source of Ore-Forming Fluid of Duolanasayi Gold Deposit, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    肖惠良; 周济元; 王鹤年; 董永观; 季俊峰; 赵宇

    2003-01-01

    The Duolanasayi gold deposit, 60 km NW of Habahe County in Xinjiang, is a medi-um-large scale gold deposit controlled by the coupled ore-forming processes involving brittle-duc-tile shearing, albitite veins, and post-stage magma solution. Fluid inclusion studies indicate thatthe homogenization temperatures range from 160℃ to 315℃ with the peak values of 220 -300℃. Mineralization pressures are from 21.0 MPa to 64.5 MPa. Ore fluid inclusions containCa2+, K+, Na+, Mg2+; HCO3-, SO242-, HS-, F-, Cl- and Au+( maximum: 5.3 × 10-6),and the mineralizing fluid is a H2O-CO2 system. Sulfur, hydrogen, oxygen and strontium isotop-ic compositions ( δS = - 2.46‰ - - 7.02‰, δ 18 OH2O = 1.65‰ - 12.4‰, δD = - 132.2‰- -51.8‰, (Sr/Sr)i =0.7043 -0.7073) suggest that the ore-forming fluid is the mixture ofmagmatic water, meteoric water, metamorphic water and formation water sealed in rocks andstrata. It is mainly magmatic water in the early stage, and mixing fluid of water, meteoric water,metamorphic water and formation water that occurred in rocks and strata in the major mineraliza-tion stage. The ore-forming materials were derived from the upper mantle or lower crust.

  5. Re Os isotopes applied to the epithermal gold deposits near Bucaramanga, northeastern Colombia

    Science.gov (United States)

    Mathur, R.; Ruiz, J.; Herb, P.; Hahn, L.; Burgath, K.-P.

    2003-01-01

    The epithermal gold mineralization near Bucaramanga, Colombia, is spatially associated with a dacitic porphyry of Upper Cretaceous to Early Tertiary age. Two mining districts in the vicinity of Bucaramanga, the California and the Vetas, host different styles of mineralization that could be interpreted as high- and low-sulfidation style mineralization, respectively. Re-Os isotope systematics were used on sulfide-gold-rich gravity concentrates in an attempt to determine both the ages of the epithermal deposits and the possible genetic relationships between the porphyry and the epithermal mineralization. The concentration of Os for sulfide samples taken from both systems is relatively uniform, ranging from 19 to 35 ppt (parts per trillion), whereas the Re concentration varies significantly, with the California system averaging 10 ppb (parts per billion) and the Vetas system averaging 140 ppb. The samples from the high-sulfidation California deposit form an isochron with an age of 57±10 Ma (MSWD=0.8), which overlaps with the age of the dacitic volcanism. The initial 187Os/ 188Os of the isochron is 1.20±0.13 and indicates a predominately crustal source for the Os and, by inference, gold. The samples from the Vetas low-sulfidation system have very high Re/Os ratios and do not lie on the isochron. These data reveal a difference between two epithermal systems that border one intrusion. Sulfide samples from the high-sulfidation system are isotopically homogenous with respect to Re-Os (form an isochron) and probably represent mineralization linked closely with the high temperature volatiles/fluids from the magma. In contrast, the sulfides from the Vetas system are in disequilibrium with respect to Re-Os and may illustrate mineralization that is not directly related to similar magmatic fluids.

  6. Structural and optical properties of gold-incorporated diamond-like carbon thin films deposited by RF magnetron sputtering

    Science.gov (United States)

    Majeed, Shahbaz; Siraj, K.; Naseem, S.; Khan, Muhammad F.; Irshad, M.; Faiz, H.; Mahmood, A.

    2017-07-01

    Pure and gold-doped diamond-like carbon (Au-DLC) thin films are deposited at room temperature by using RF magnetron sputtering in an argon gas-filled chamber with a constant flow rate of 100 sccm and sputtering time of 30 min for all DLC thin films. Single-crystal silicon (1 0 0) substrates are used for the deposition of pristine and Au-DLC thin films. Graphite (99.99%) and gold (99.99%) are used as co-sputtering targets in the sputtering chamber. The optical properties and structure of Au-DLC thin films are studied with the variation of gold concentration from 1%-5%. Raman spectroscopy, atomic force microscopy (AFM), Vickers hardness measurement (VHM), and spectroscopic ellipsometry are used to analyze these thin films. Raman spectroscopy indicates increased graphitic behavior and reduction in the internal stresses of Au-DLC thin films as the function of increasing gold doping. AFM is used for surface topography, which shows that spherical-like particles are formed on the surface, which agglomerate and form larger clusters on the surface by increasing the gold content. Spectroscopy ellipsometry analysis elucidates that the refractive index and extinction coefficient are inversely related and the optical bandgap energy is decreased with increasing gold content. VHM shows that gold doping reduces the hardness of thin films, which is attributed to the increase in sp2-hybridization.

  7. Site-selective deposition of gold nanoparticles using non-adiabatic reaction induced by optical near-fields

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, Kokoro; Yatsui, Takashi; Kawazoe, Tadashi; Sugiyama, Masakazu; Ohtsu, Motoichi, E-mail: kitamura@nanophotonics.t.u-tokyo.ac.jp [Department of Electrical Engineering and Information Systems, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Nanophotonics Research Center, University of Tokyo, Tokyo 113-8656 (Japan)

    2010-07-16

    In this paper, we report on site-selective deposition of metal nanoparticles using a non-adiabatic photochemical reaction. Photoreduction of gold was performed in a silica gel membrane containing tetrachloroaurate (AuCl{sub 4}{sup -}) ions, using ZnO nanorods as the sources of optical near-field light, resulting in deposition of gold nanoparticles with an average diameter of 17.7 nm. The distribution of distances between the gold nanoparticles and nanorod traces revealed that the gold nanoparticles were deposited adjacent to the ZnO nanorods, reflecting the attenuation of the optical near-fields in the vicinity of the ZnO nanorods. We found that the emission wavelength from the ZnO nanorods was longer than the absorption edge wavelength of the tetrachloroaurate. Additionally, from the intensity distribution obtained by a finite-difference time-domain method, the gold deposited around the ZnO nanorods was found to be due to a non-adiabatic photochemical reaction.

  8. Discriminating fluid source regions in orogenic gold deposits using B-isotopes

    Science.gov (United States)

    Lambert-Smith, James S.; Rocholl, Alexander; Treloar, Peter J.; Lawrence, David M.

    2016-12-01

    The genesis of orogenic gold deposits is commonly linked to hydrothermal ore fluids derived from metamorphic devolatilization reactions. However, there is considerable debate as to the ultimate source of these fluids and the metals they transport. Tourmaline is a common gangue mineral in orogenic gold deposits. It is stable over a very wide P-T range, demonstrates limited volume diffusion of major and trace elements and is the main host of B in most rock types. We have used texturally resolved B-isotope analysis by secondary ion mass spectrometry (SIMS) to identify multiple fluid sources within a single orogenic gold ore district. The Loulo Mining District in Mali, West Africa hosts several large orogenic gold ore bodies with complex fluid chemistry, associated with widespread pre-ore Na- and multi-stage B-metasomatism. The Gara deposit, as well as several smaller satellites, formed through partial mixing between a dilute aqueous-carbonic fluid and a hypersaline brine. Hydrothermal tourmaline occurs as a pre-ore phase in the matrix of tourmalinite units, which host mineralization in several ore bodies. Clasts of these tourmalinites occur in mineralized breccias. Disseminated hydrothermal and vein hosted tourmaline occur in textural sites which suggest growth during and after ore formation. Tourmalines show a large range in δ11B values from -3.5 to 19.8‰, which record a change in fluid source between paragenetic stages of tourmaline growth. Pre-mineralization tourmaline crystals show heavy δ11B values (8-19.8‰) and high X-site occupancy (Na ± Ca; 0.69-1 apfu) suggesting a marine evaporite source for hydrothermal fluids. Syn-mineralization and replacement phases show lighter δ11B values (-3.5 to 15.1‰) and lower X-site occupancy (0.62-0.88 apfu), suggesting a subsequent influx of more dilute fluids derived from devolatilization of marine carbonates and clastic metasediments. The large, overlapping range in isotopic compositions and a skew toward the

  9. Geology and Geochemistry of Reworking Gold Deposits in Intrusive Rocks of China—Ⅰ. Features of the Intrusive Rocks

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 程景平; 等

    1998-01-01

    Most gold deposits in intrusive rocks were formed as a result of reworking processes.the intrusive rocks containing gold deposits and consisting of ultramafic-mafic,intermediateacid and alkaline rocks of the Archean,Proterozoic,Caledonian,Hercynian and Yenshanian periods occur in cratons,activated zones of cratons and fold belts.Among them,ultramaficmafic rocks,diorite,alkaline rocks,and anorthosite are products of remelting in the mantle or mantle-crust or mantle with crustal contamination,However,auriferous intermediate-acid rocks are products of metasomatic-remelting in auriferous volcainc rocks or auriferous volcanosedimentary rocks in the deep crust.

  10. Geochemical Characteristics of the Jinjiazhuang Ultrabasic Rock—Type Gold Deposit in Chicheng County,Hebei Province

    Institute of Scientific and Technical Information of China (English)

    李红阳; 杨竹森; 等

    2000-01-01

    The Jinjiazhuang gold deposit occurs in the Zhangjiakou gold field,Northwest Hebei.The ore bodies are mostly hosted in Xiaozhangjiakou ultrabasic rocks dominated by diopsidite.Electron microprobe analyses indicate that the deposit is characterized by the enrichment of some platinum group elements in principal metallic minerals such as chalcopyrite,galena,sphalerite and pyrite,and the presence of millerite,Stable isotope studies show that carbon,sulfur and most of the metallogenic elements were probably derived largely from the host Xiaozhangjiakou ultrabasic rocks and that it is possible that the ore-forming fluid was predominted by meteoric water.

  11. DNA Functionalized Direct Electro-deposited Gold nanoaggregates for Efficient Detection of Salmonella typhi.

    Science.gov (United States)

    Singh, Anu; Choudhary, Meenakshi; Singh, M P; Verma, H N; Singh, Surinder P; Arora, Kavita

    2015-10-01

    Direct electro-deposition of gold nano-aggregates (GNAs) was carried out to fabricate electrochemical DNA biosensor for the detection of Salmonella typhi in urine and blood samples. Size of depositing GNAs was controlled by regulating electro-deposition parameters at physiological pH. This facilitated achieving biocompatible GNAs with desired electrochemical behaviour and enhanced surface area to achieve higher DNA loading. Salmonella typhi (S. typhi) specific 5'amine modified single stranded DNA (ssDNA, NH2-(C6)-5'CGTGCGCGACGCCCGCCGCC3') was covalently immobilized on to GNAs-ITO (indium tin oxide) electrode. Dynamic detection range of 4 aM - 24 fM. using methylene blue (MB) redox indicator at 25 °C was achieved using ssDNA-GNAs-ITO bio-electrode to detect the complimentary target sequence (5'GGCGGCGGGCGTCGCGCACG 3') through differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Selectivity of designed electrode was ascertained by response signal for complementary, non-complementary and 1 base mismatch sequences. Furthermore, clear distinction in complementary and non-complimentary targets was obtained by EIS studies for genomic DNA in culture spiked biological fluids 'CSBF' (blood and urine). This study for detection of S. typhi from urine and blood samples using fabricated ssDNA-GNA-ITO bio-electrode showed promising results and have potential to be used as sensor for real patient samples.

  12. Selective detection of endotoxin using an impedance aptasensor with electrochemically deposited gold nanoparticles.

    Science.gov (United States)

    Su, Wenqiong; Kim, Sung-Eun; Cho, MiSuk; Nam, Jae-Do; Choe, Woo-Seok; Lee, Youngkwan

    2013-01-01

    Using a single-stranded DNA (ssDNA) aptamer exhibiting high binding affinity (Kd = 12 nM) to endotoxin as a probe, an impedance sensor where aptamer-conjugated gold nanoparticles (AuNPs) were electrochemically deposited on a gold electrode was fabricated and its performance in regard to endotoxin detection assessed. AuNPs have been employed widely as biosensors because of their unique physical and chemical properties. In order to maximize the performance of the impedance aptasensor on endotoxin detection, some critical factors affecting aptamer conjugation to AuNPs and target recognition ability (i.e. concentrations of aptamer coupled with AuNPs, pH, ion strength and cation effect at the time of aptamer-endotoxin interaction) were optimized. Electrochemical impendence spectroscopy, cyclic voltametry, atomic force microscope, scanning electron microscope and quartz crystal microbalance were employed to characterize all the modification/detection procedures during the sensor fabrication. The developed aptasensor showed a broad linear dynamic detection range (0.01-10.24 ng/ml) with a very low detection limit for endotoxin (0.005 ng/ml), despite the presence of several biomolecules (e.g. plasmid DNA, RNA, serum albumin, Glc and sucrose) known to interfere with other endotoxin assays. The demonstrated aptasensor required a detection time of only 10 min, providing a simple and fast analytical method to specifically detect endotoxin from complex biological liqors.

  13. Transportation of REE in the Ductile Shear Zone in Hetai Gold Deposit, Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    杨凤根; 王鹤年; 华仁民

    2003-01-01

    The REE transportation in two sorts of mylonites of ductile shear zone, in Hetai gold deposit, Guangdong province was studied. The results show that there is REE compositional variation regularly in the ductile shear zone. When mica-quartz schist and migmatite are changing into mylonites or ultramylonites, I.e., along with intensifying deformation, the contents of each rare earth element and the total contents of the LREE, HREE and REE increase or decrease regularly, but the REE patterns of the rock are accordant. The isocon diagram of the tectonic rocks before and after deformation shows that the REE compositional variation of the mylonites or ultramylonites are very small, but there is a few REE moving in or out in the rock deformation. The reason of the REE compositional variation is that there are volume change and fluid flow in the rock deformation, and it leads to the LREE relative enrichment and HREE relative loss.

  14. Analysis of Ore-Controlling Structures of the Xincheng-Hexi Gold Deposit, Shandong Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on quantitative and semi-quantitative mathematical and mechanical analysis of the shape, motion, structural factors, stress field and deformation field of the ore-hosting faults in the Xincheng-Hexi gold deposit, the ore-controlling features of faults and mineralization mechanism are discussed. It is concluded that the mineralization is controlled by the main faults, subsidiary fractures, joint density, mechanical features and deformation of the faults. The ore bodies are mainly located in the lower part of the convex crest and upper part of the concave trough of the main undulating fault surface. Mineralization is positively correlated to the development of subsidiary fractures and joints, which correspond to zones of low internal stress and high body strain and shear strain. They are favourable positions for mineralization and alteration.

  15. Geochemical Features of Ore Fluid for Gold Deposits Related to Alkaline Rocks in China

    Institute of Scientific and Technical Information of China (English)

    齐金忠; 李莉

    2000-01-01

    Fluid inclusion studies of 5 gold deposits connected with alkaline rocks show that quartz separated from auriferous quartz veins contains abundant three-phase CO2-NaCl-H2O inclusions and two-phase CO2-dominated ones,measuring 5-20um in diameter,Homogenization temperatures of the fluid inclusions are mostly within the range of 150-300℃,and the salinities,mainly 0.2wt%-12 wt%(NaCl),Gold mineralizations occurred at depths of 1.4-2.8km,The most striking character of fluid composition is that among the cations,Na+ in dominant,followed by K+,Ca2+,among the anions,Cl- is slightly higher than SO42-,In the evaporate,H2O is dominant,followed by CO2,The pH values are mainly within the range of 6.5-8.5,indicating that the ore-forming solutions are alkaline in nature.The hydrogen and oxygen isotopic ratios indicate that the ore fluid is composed mainly of magmatic water.With the dropping of temperature in the ore fluid,the contents of CO2 decreased while the salinity increased.The relations between Au and other components of the ore fluid are discussed in the paper,and it is concluded that in these deposits,Chlorides,H2S,SiO2,CO2,etc.in the fluid all are involved in the migration and concentration of Au.

  16. High and Low Temperature Gold Mineralizations in the Fe–Cu–Zn Sulfide Deposits of Corchia Ophiolite, Northern Italian Apennine

    Directory of Open Access Journals (Sweden)

    Zaccarini Federica

    2013-03-01

    Full Text Available Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS deposits of Corchia ophiolite (Parma province, Italy in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and sedimentary rocks. The Pozzo mineralization is hosted by a serpentinite. Concentrations of gold up to 3070 ppb have been reported for the Cantiere Donnini and up to 6295 ppb in the Pozzo mine. According to the field relationships, gold composition, mineralogical assemblage and sulfur isotope data, we can conclude that two different types of gold mineralization have been recognized in the Corchia ophiolite: (1 formed at low temperature in submarine environment (Cantiere Donnini and Speranza and (2 formed at high temperature in the oceanic mantle (Pozzo by segregation of an immiscible sulfide liquid.

  17. Direct sputtering- and electro-deposition of gold coating onto the closed surface of ultralow-density carbon-hydrogen foam cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jiaqiu; Yin, Jialing; Zhang, Hao; Yao, Mengqi; Hu, Wencheng, E-mail: huwc@uestc.edu.cn

    2016-12-15

    Highlights: • The surface pores of P(DVB/St) foam cylinder are sealed by CVD method. • Gold film was deposited on the surface of foam cylinder by magnetron sputtering. • Electroless plating was excluded in the present experiments. • The gold coatings were thickened through the electrodeposition process. - Abstract: This work aimed to fabricate a gold coating on the surface of ultralow-density carbon-hydrogen foam cylinder without electroless plating. Poly (divinylbenzene/styrene) foam cylinder was synthetized by high internal phase emulsion, and chemical vapor deposition polymerization approach was used to form a compact poly-p-xylylene film on the foam cylinder. Conducting gold thin films were directly deposited onto the poly-p-xylylene-modified foam cylinder by magnetron sputtering, and electrochemical deposition was adopted to thicken the gold coatings. The micro-structures and morphologies of poly (divinylbenzene/styrene) foam cylinder and gold coating were observed by field-emission scanning electron microscopy. The gold coating content was investigated by energy-dispersive X-ray. The thicknesses of poly-p-xylylene coating and sputtered gold thin-film were approximately 500 and 100 nm, respectively. After electrochemical deposition, the thickness of gold coating increased to 522 nm, and the gold coating achieved a compact and uniform structure.

  18. ‘Indicator’ carbonaceous phyllite/graphitic schist in the Archean Kundarkocha gold deposit, Singhbhum orogenic belt, eastern India: Implications for gold mineralization vis-a-vis organic matter

    Indian Academy of Sciences (India)

    P R Sahoo; A S Venkatesh

    2014-10-01

    Carbonaceous rocks in the form of graphitic schist and carbonaceous phyllite are the major host rocks of the gold mineralization in Kundarkocha gold deposit of the Precambrian Singhbhum orogenic belt in eastern India. The detection of organic carbon, essentially in the carbonaceous phyllite and graphitized schist within the Precambrian terrain, is noted from this deposit. A very close relationship exists between gold mineralization and ubiquitous carbonaceous rocks containing organic carbon that seems to play a vital role in the deposition of gold in a Precambrian terrain in India and important metallogenetic implications for such type of deposits elsewhere. However, the role played by organic matter in a Precambrian gold deposit is debatable and the mechanism of precipitation of gold and other metals by organic carbon has been reported elsewhere. Fourier transform infrared spectroscopy (FTIR) results and total organic carbon (TOC) values suggest that at least part of the organic material acted as a possible source for the reduction that played a significant role in the precipitation of gold. Lithological, electron probe analysis (EPMA), fluid inclusions associated with gold mineralization, Total Carbon (TC), TOC and FTIR results suggest that the gold mineralization is spatially and genetically associated with graphitic schist, carbonaceous phyllite/shale that are constituted of immature organic carbon or kerogen. Nano-scale gold inclusions along with free milling gold are associated with sulfide mineral phases present within the carbonaceous host rocks as well as in mineralized quartz-carbonate veins. Deposition of gold could have been facilitated due to the organic redox reactions and the graphitic schist and carbonaceous phyllite zone may be considered as the indicator zone.

  19. Evaluating the Metal Source(s) of Iron Oxide-Copper-Gold (IOCG) Deposits (Invited)

    Science.gov (United States)

    Simon, A. C.; Bilenker, L.; Lundstrom, C.; Reich, M.; Barra, F.; Hanchar, J. M.; Westhues, A.

    2013-12-01

    Iron oxide - copper - gold deposits (IOCG) are characterized by high modal abundances of magnetite and/or hematite, ubiquitous and variable grades of Cu and Au, and, often, economic grades of other metals including REE, U, Ag, Mo and Zn. The largest deposits contain >1 billion tonnes of iron. There seems to be a general consensus that metals in IOCG deposits were transported by, and precipitated from, aqueous fluids. However, there is a lack of agreement for the source of the metal-bearing aqueous fluid(s) as well as the source of iron and other metals (i.e., magmatic or hydrothermal, or some combination of the two). Published fluid inclusion data indicate that metal-bearing aqueous fluids were trapped over a wide range of temperatures, with homogenization temperatures between 500 and 600 °C for inclusions associated with the precipitation of iron-oxide minerals, and between 300 and 500 °C for inclusions associated with main-stage sulfides (e.g., chalcopyrite, pyrite). The high trapping temperatures for fluid inclusions and the observation that some IOCG deposits appear to be related temporally and spatially to igneous intrusions, characteristics similar to those observed for porphyry-type ore deposits, have led some authors to propose that magmatic-hydrothermal aqueous fluids are responsible for IOCG formation. Others, however, favor a genetic model that invokes large-scale circulation of basinal brines, which are heated by magmatic intrusions and subsequently leach Fe and other metals from the crust. Evidence cited for this model includes the pervasive alkali metasomatism associated with some IOCG deposits, and the depletion of Fe, Cu and Au in some deposit wall rocks. Stable isotope evidence thus far is inconclusive. Published d34S values for IOCG deposits range from -30 to +30, but generally cluster around zero per mil. d18O ranges from ~0 to +10 per mil. Chlorine isotope values for fluids in inclusions liberated from quartz, calcite and apatite are

  20. Origin of Gold—Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit,Shandong Province

    Institute of Scientific and Technical Information of China (English)

    邓军; 孙忠实; 等

    2002-01-01

    The composition of quartz inclusions and trace elements in ore indicate that gold-bearing fluid in the Xiadian gold deposit,Shandong Province,stemmed from both mantle and magma,belonging to a composite origin.Based on theoretical analysis and high temperature and high pressure experimental studies,gold-bearing fluid initiative localization mechanism and the forming environment of ore-host rocks are discussed in the present paper.The composite fluid extracted gold from rocks because of its expanding and injecting forces and injecting forces and flew through ore-conducive structures,leading to the breakup of rocks.The generation of ore-host faults and the precipitation of gold-bearing fluid occurred almost simultaneously.This study provides fur-ther information about the relationships between gold ore veins and basic-ultrabasic vein rocks and intermediate vein rocks,the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.

  1. Noble gases fingerprint a metasedimentary fluid source in the Macraes orogenic gold deposit, New Zealand

    Science.gov (United States)

    Goodwin, Nicholas R. J.; Burgess, Ray; Craw, Dave; Teagle, Damon A. H.; Ballentine, Chris J.

    2017-02-01

    The world-class Macraes orogenic gold deposit (˜10 Moz resource) formed during the late metamorphic uplift of a metasedimentary schist belt in southern New Zealand. Mineralising fluids, metals and metalloids were derived from within the metasedimentary host. Helium and argon extracted from fluid inclusions in sulphide mineral grains (three crush extractions from one sample) have crustal signatures, with no evidence for mantle input (R/Ra = 0.03). Xenon extracted from mineralised quartz samples provides evidence for extensive interaction between fluid and maturing organic material within the metasedimentary host rocks, with 132Xe/36Ar ratios up to 200 times greater than air. Similarly, I/Cl ratios for fluids extracted from mineralised quartz are similar to those of brines from marine sediments that have interacted with organic matter and are ten times higher than typical magmatic/mantle fluids. The Macraes mineralising fluids were compositionally variable, reflecting either mixing of two different crustal fluids in the metasedimentary pile or a single fluid type that has had varying degrees of interaction with the host metasediments. Evidence for additional input of meteoric water is equivocal, but minor meteoric incursion cannot be discounted. The Macraes deposit formed in a metasedimentary belt without associated coeval magmatism, and therefore represents a purely crustal metamorphogenic end member in a spectrum of orogenic hydrothermal processes that can include magmatic and/or mantle fluid input elsewhere in the world. There is no evidence for involvement of minor intercalated metabasic rocks in the Macraes mineralising system. Hydrothermal fluids that formed other, smaller, orogenic deposits in the same metamorphic belt have less pronounced noble gas and halogen evidence for crustal fluid-rock interaction than at Macraes, but these deposits also formed from broadly similar metamorphogenic processes.

  2. Palladium, Platinum and Gold Concentrations in Fengshan Porphyry Cu-Mo Deposit, Hubei Province, China

    Institute of Scientific and Technical Information of China (English)

    WANG Minfang; DENG Xiaodong; BI Shijian; LI Zhanke

    2009-01-01

    The Fengshan porphyry-skarn copper-molybdenum (Cu-Mo) deposit is located in the south-eastern Hubei Province in east China. Cu-Mo mineralization is hosted in the Fengshan granodiorite porphyry stock that intruded the Triassic Daye Formation carbonate rocks in the early Cretaceous (~140 Ma), as well as the contact zone between granodiorite porphyry stock and carbonate rocks, forming the porphyry-type and skarn-type association. The Fengshan granodiorite stock and the immediate country rocks are strongly fractured and intensely altered by hydrothermal fluids. In addition to intense skarn alteration, the prominent alteration types are potassic, phyllic, and propylitic, whereas argillation is less common. Mineralization occurs as veins, stock works, and disseminations, and the main ore minerals are chalcopyrite, pyrite, molybdenite, bornite, and magnetite. The contents of palladium, platinum and gold (Pd, Pt and Au) are determined in nine samples from fresh and mineralized granodiorite and different types of altered rocks. The results show that the Pd content is systematically higher than Pt, which is typical for porphyry ore deposits worldwide. The Pt content ranges from 0.037 tul.765 ppb, and the Pd content ranges between 0.165and 17.979 ppb. Pd and Pt are more concentrated in porphyry mineralization than skarn mineralization, and have negative correlations with Au. The reconnaissance study presented here confirms the existence of Pd and Pt in the Fengshan porphyry-skarn Cu-Mo deposit. When compared with intracontinent and island arc geotectonic settings, the Pd, Pt, and Au contents in the Fengshan porphyry Cu-Mo deposit in the intracontinent is lower than the continental margin types and island are types. A combination of available data indicates that Pd and Pt were derived from oxidized alkaline magmas generated by the partial melting of an enriched mantle source.

  3. Orogenesis, high-T thermal events, and gold vein formation within metamorphic rocks of the Alaskan Cordillera

    Science.gov (United States)

    Goldfarb, R.J.; Snee, L.W.; Pickthorn, W.J.

    1993-01-01

    Mesothermal, gold-bearing quartz veins are widespread within allochthonous terranes of Alaska that are composed dominantly of greenschist-facies metasedimentary rocks. The most productive lode deposits are concentrated in south-central and southeastern Alaska; small and generally nonproductive gold-bearing veins occur upstream from major placer deposits in interior and northern Alaska. Ore-forming fluids in all areas are consistent with derivation from metamorphic devolatilisation reactions, and a close temporal relationship exists between high-T tectonic deformation, igneous activity, and gold mineralization. Ore fluids were of consistently low salinity, CO2-rich, and had ??18O values of 7 ???-12??? and ??D values between -15??? and -35???. Upper-crustal temperatures within the metamorphosed terranes reached at least 450-500??C before onset of significant gold-forming hydrothermal activity. In southern Alaska, gold deposits formed during latter stages of Tertiary, subduction-related, collisional orogenesis and were often temporally coeval with calc-alkaline magmatism. -from Authors

  4. Structural geochemistry of gold mineralization in the Linglong-Jiaojia district, Shandong Province, China

    Institute of Scientific and Technical Information of China (English)

    Huan-zhang LU; Guy Archambault; LI Yuansheng; WEI Jiaxue

    2007-01-01

    The Linglong-Jiaojia district is one of the most important regions containing gold deposits in China. These gold deposits can be divided into: a) the pyrite-gold-quartz vein type (Linglong type), which is controlled by brittle-ductile to ductile deformation structures, and b) the alteration-zone type (Jiaojia type), characterized by small veinlets, or the disseminated type recognized in brittle shear zones. Lode gold deposits in the Jiaojia area occur in NE brittle fracture zones, formed in a dominantly simple shear deformation regime, mainly in thrust attitude with a minor sinistral strike slip component. In the Linglong area, the lode gold deposits are located at the intersection of three types of structures: NNE and NE brittle-ductile fault zones and the ENE ductile reverse shear zone in the south of the area. The structural characteristics of these brittle shear zones are consistent with a tectonic NNW-SSE principal stress field orientation. Similar stresses explain the ENE Qixia fold axes, the Potouqing and several other ENE reverse ductile shear zones elsewhere in the region, the Tancheng-Lujiang fault zone and its subsidiaries in the vicinity of the Linglong-Jiaojia district, as well as the southern ENE suture zone north of Qingdao. Therefore these structural systems occurred as part of different major tectonic events under NNW-SSE compression principal stress fields in the area.Gold deposits are hosted in smaller-scale structures within the brittle fault zones and brittle-ductile shear zones. Although ore bodies and, on a smaller scale, quartz ore veins often seem to be randomly oriented, it is possible to explain their distribution and orientation in terms of the simple shear deformation process under which they were developed. The progressive simple shear failure is characterized by various fracture modes (tension and shear) that intervene in sequence. The tension and shear fractures are influenced by the stress level (depth of burial beneath the

  5. Geochemical and fluid zonation in the skarn environment at the tomboy-minnie gold deposits, Lander County, Nevada

    Science.gov (United States)

    Theodore, T.G.; Howe, S.S.; Blake, D.W.; Wotruba, P.R.

    1986-01-01

    The Tomboy-Minnie gold deposits are related to the middle Tertiary porphyry copper system centered at Copper Canyon. Gold-silver ores in the deposits occur mostly in a pyrrhotite- and pyrite-rich basal 30-m-thick sequence of altered calcareous conglomerate belonging to the Middle Pennsylvanian Battle Formation. The entire mineralized system contained at least 3.3 million troy oz gold before large-scale mining operations began. Alteration in the Tomboy-Minnie deposits includes actinolite- and chlorite-dominant assemblages, in marked contrast to the skarn, potassic, and phyllic assemblages characterizing the copper-gold-silver deposits of the system. Introduction of gold occurred penecontemporaneously with replacement of early diopside-alteration assemblages by actinolite and chlorite. Metals are zoned strongly in the Copper Canyon system: the West and East ore bodies occur in a copper-gold-silver zone that is followed outward by a gold-silver zone which includes the Tomboy deposit and in turn, is succeeded by a lead-zinc-silver zone. Locations of drill holes that have Au/Ag assay ratios of ??? 1 clearly outline the Tomboy-Minnie deposits within an area of rocks with Au/Ag ratios of ??? 0.5. Fluid-inclusion studies suggest wide variations in temperature and chemistry prevailed in the fluids associated with mineralization at the Tomboy. Early fluids associated with diopsidequartz assemblages probably were dominantly CaCl2-rich brines and were boiling at temperatures higher than 500??C. These fluids were progressively enriched in sodium and potassium over time, and during the hydrosilicate stages, temperatures probably ranged from 320 to 500??C at the time actinolite formed, and from 220 to 320??C at the time chlorite was dominant. Sulfur isotopic data suggest that sulfur, mostly from a magmatic or deep-seated crustal source, was transported by hydrothermal fluids as aqueous H2S with a ?? 34S of about 4 ?? 1??? to the West, East, and Tomboy deposits. ?? 1986.

  6. Lithologic controls on mineralization at the Lagunas Norte high-sulfidation epithermal gold deposit, northern Peru

    Science.gov (United States)

    Cerpa, Luis M.; Bissig, Thomas; Kyser, Kurt; McEwan, Craig; Macassi, Arturo; Rios, Hugo W.

    2013-06-01

    The 13.1-Moz high-sulfidation epithermal gold deposit of Lagunas Norte, Alto Chicama District, northern Peru, is hosted in weakly metamorphosed quartzites of the Upper Jurassic to Lower Cretaceous Chimú Formation and in overlying Miocene volcanic rocks of dacitic to rhyolitic composition. The Dafne and Josefa diatremes crosscut the quartzites and are interpreted to be sources of the pyroclastic volcanic rocks. Hydrothermal activity was centered on the diatremes and four hydrothermal stages have been defined, three of which introduced Au ± Ag mineralization. The first hydrothermal stage is restricted to the quartzites of the Chimú Formation and is characterized by silice parda, a tan-colored aggregate of quartz-auriferous pyrite-rutile ± digenite infilling fractures and faults, partially replacing silty beds and forming cement of small hydraulic breccia bodies. The δ34S values for pyrite (1.7-2.2 ‰) and digenite (2.1 ‰) indicate a magmatic source for the sulfur. The second hydrothermal stage resulted in the emplacement of diatremes and the related volcanic rocks. The Dafne diatreme features a relatively impermeable core dominated by milled slate from the Chicama Formation, whereas the Josefa diatreme only contains Chimú Formation quartzite clasts. The third hydrothermal stage introduced the bulk of the mineralization and affected the volcanic rocks, the diatremes, and the Chimú Formation. In the volcanic rocks, classic high-sulfidation epithermal alteration zonation exhibiting vuggy quartz surrounded by a quartz-alunite and a quartz-alunite-kaolinite zone is observed. Company data suggest that gold is present in solid solution or micro inclusions in pyrite. In the quartzite, the alteration is subtle and is manifested by the presence of pyrophyllite or kaolinite in the silty beds, the former resulting from relatively high silica activities in the fluid. In the quartzite, gold mineralization is hosted in a fracture network filled with coarse alunite

  7. Development of a metadata schema describing Institutional Repository content objects enhanced by ''LODE-BD'' strategies

    Directory of Open Access Journals (Sweden)

    Iryna Solodovnik

    2013-07-01

    Full Text Available Basato sulle "Linee guida per la creazione e la gestione di metadati nei repository istituzionali” (CRUI, Italia, 2012, sulle "Raccomandazioni LODe BD” (AIMS, 2012 e, sull'esplorazione di altri principi e strategie per lo sviluppo qualitativo dei metadati che rappresentano il contenuto e le proprietà dei contenuti digitali, questo articolo presenta il profilo specifico dei metadati per la descrizione dei dati relativi alle risorse depositate negli archivi istituzionali. Questo profilo è allocato all'interno di uno schema di metadati fornito da termini ben definiti, dalle specifiche di compilazione, dalle strategie di allineamento (mappatura per specifici termini di metadati e dal valore della proprietà che consente ai metadati base di diventare più efficienti nel contesto del controllo d'autorità, più ricchi nei loro profili semantici, più accessibili e utilizzabili in rete per mezzo dei Linked Data. Lo sviluppo e l'implementazione degli schemi di metadati completamente o parzialmente allineati con il paradigma dei Linked Data, fornirà lo scambio tra i differenti metadati, potenziando così la relazione semantica, l'interrogazione del loro contenuto e la loro partecipazione ai Linked Open Data.

  8. Alteration and petrology of Intrusive Rocks associated with Gold Mineralization at Kuh-E-Zar Gold Deposit, Torbat-e-Heydaryeh

    Directory of Open Access Journals (Sweden)

    Alireza Mazloumi Bajestani

    2009-09-01

    Full Text Available Kuh- e -Zar gold deposit located 35 km west of Torbat-e-Heydaryeh, (Khorassan e- Razavi province, East of Iran. This deposit is a specularite-rich Iron oxide type (IOCG. This mine is situated within Khaf-Bardascan volcanic plutonic belt. Based on recent exploration along this belt, several IOCG type system plus Kuh-e-Zar deposit are discovered. In the study area, several type of tuff and lava having acid to intermediate composition are identified (upper Eocene. Oligo-Miocene granite, granodiorite, synogranite and monzonite intruded upper Eocene andesite-dacite-rhyolite. Intrusive rocks are meta-aluminous, medium to high-K series I-type. Based on spider diagram, intrusive rocks show enrichment in LILE = K, Th, Rb and depletion in HFSE = Nb, Sr, Ti. Based geochemistry of igneous rock, they formed in continental margin subduction zone. Propylitic (chlorite alteration is dominated and covers large area. Silicification is restricted only to mineralized zones. Argillic and albitization is found in certain location and cover small areas. The style of mineralization was controlled by the type and geometry of fault zones. Mineralization is found as vein, stockwork and breccias. Hypogene mineral Paragenesis include: specularite-quartz-gold-chlorite ± chalcopyrite ± pyrite ± galena ± barite. Secondary minerals formed due to oxidation are: goethite, limonite, lepidocrucite, Malachite, Azurite, Covelite, Cerucite, hydrocerucite, Pyrolusite and Smitsonite. In a few localities, chalcopyrite and minor pyrite and galena are found. Based on SEM analysis gold is present as electrum. Mineralization appeared in different type such as vein, stockwork and Hydrothermal breccia in strike sleep fault zone which are hidden inside volcano plutonic rocks. The average gold grade is between 3.02 ppm and ore reserve is estimated more than 3 million tons (cut off grade = 0.7 ppm.

  9. Direct-write deposition and focused-electron-beam-induced purification of gold nanostructures.

    Science.gov (United States)

    Belić, Domagoj; Shawrav, Mostafa M; Gavagnin, Marco; Stöger-Pollach, Michael; Wanzenboeck, Heinz D; Bertagnolli, Emmerich

    2015-02-04

    Three-dimensional gold (Au) nanostructures offer promise in nanoplasmonics, biomedical applications, electrochemical sensing and as contacts for carbon-based electronics. Direct-write techniques such as focused-electron-beam-induced deposition (FEBID) can provide such precisely patterned nanostructures. Unfortunately, FEBID Au traditionally suffers from a high nonmetallic content and cannot meet the purity requirements for these applications. Here we report exceptionally pure pristine FEBID Au nanostructures comprising submicrometer-large monocrystalline Au sections. On the basis of high-resolution transmission electron microscopy results and Monte Carlo simulations of electron trajectories in the deposited nanostructures, we propose a curing mechanism that elucidates the observed phenomena. The in situ focused-electron-beam-induced curing mechanism was supported by postdeposition ex situ curing and, in combination with oxygen plasma cleaning, is utilized as a straightforward purification method for planar FEBID structures. This work paves the way for the application of FEBID Au nanostructures in a new generation of biosensors and plasmonic nanodevices.

  10. Geochronology of the granitoid hosted Salamangone gold deposit, Lourenco district, Amapa State, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Sonia Aparecida Abissi [Secretaria de Meio Ambiente, Sao Paulo, SP (Brazil). Instituto Geologico]. E-mail: snogueira@igeologico.sp.gov.br; Bettencourt, Jorge Silva [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica]. E-mail: jsbetten@usp.br; Tassinari, Colombo Celso Gaeta [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas]. E-mail: ccgtassi@usp.br

    2000-06-01

    The Salamangone deposit occurs in the Lourenco Gold District, Amapa. It is associated to Paleoproterozoic Metamorphosed supracrustal rocks and a calc-alkaline complex. The deposit lies within a metaluminous weakly peraluminous, calc-alkaline tonalitic-granodioritic pluton. The Au-mineralization consists on an epigenetic quartz-vein system, enriched in Au and As and structurally controlled by a ductile-brittle shear zone. U-Pb zircon analysis of tonalite gave a crystallization age of 2.16 {+-} 0.13 Ga, whereas Sm-Nd T{sub DM} model ages of tonalite and granodiorite range from 2.24 to 2.34 Ga. e{sub Nd} (T) vary from 2.88 to 3.02. Additional whole rock Rb-Sr isochron ages on granitoids yielded values in the range of 2.17 to 2.28 Ga, with {sup 87} Sr/{sup 86} Sr initial ratio of 0.702. The isotopic data and geochemical signature of granitoids suggest that the Lourenco region, as well as the neighboring areas in French Guyana, represents a vast area largely floored by accreted juvenile arc terranes without evidence of Archean crust contamination, being related to the development of a calc-alkaline magmatic arc, which was produced within the Maroni-Itacaiunas Province, during a major Paleoproterozoic orogenic event. (author)

  11. 小西南岔金铜矿床金的赋存状态研究%Study on occurrence status of gold in Xiaoxinancha Copper-Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    董国振

    2014-01-01

    小西南岔金铜矿床属次火山—斑岩型矿床,矿化类型主要为浸染型和硫化物方解石石英脉型。通过电子探针及显微镜下分析,结果表明,矿石中金矿物主要为自然金、银金矿;金矿物形态复杂多样,以显微金和细粒金为主;金矿物的嵌存状态以包裹金、粒间金为主。金主要富集于硫化物方解石石英脉中,在空间上金多分布在矿体中上部。%Xiaoxinancha Copper -Gold Deposit is a secondary volcanic-porphyry type deposit .The mineralization type is mainly dissemination and sulfide calcite quartz vein type .Electronic probe and microscope analyses show that gold minerals mainly take the form of native gold and electrum;gold minerals are complex ,dominated by micro gold and fine particle gold;gold minerals are embedded as locked gold and intergranular gold .Gold is primarily enriched in sulfide calcite quartz veins and is spatially deposited in the middle and upper part of orebodies .

  12. Ore—Fluid Systems of Fine Disseminated Gold Deposits Along the Southeastern Margin of the Yangtze Plate

    Institute of Scientific and Technical Information of China (English)

    张景荣; 朱恺军; 等

    1995-01-01

    Fine disseminated gold deposits occurring along the southeastern margin of the Yangtze Plate belong to the epithermal type resulting from different systems of ore-forming fluids.According to their sources, the ore-forming fluids can be divided into four systems: a)meteoric water system; b)oil-brine system; c)basin-brine system;and d)magmatic-formation water system.The four hydrothermal systems are responsible for four types of gold deposits, respectively.The meteoric water system produces hot spring gold deposits. The basin-brines,which are derived from fissure water, structural water and absorbed water sealed up in strata, are responsible for the absin-brine-type deposits.The oil-brine system, having the same source as the bain-brines ,is characterized by the involvement of organic matter and is responsible for the oil-brine-type deposits. Inclusion fluid data show that there are obvious differences in chemical composition and carbon, oxygen,hydrogen and sulfur isotopes for these hydrothermal systems.Different metallogenic provinces, in which one of the four systems is dominant, can be recognized in the region.

  13. The economic efficiency of investment in the development of reserves of small groups of geographically contiguous gold deposits

    Directory of Open Access Journals (Sweden)

    Evdokimov S.I.

    2017-01-01

    Full Text Available The object of the research is a group of geographically contiguous low volume gold deposits. The subject of the study is an economic justification for a way to involve economic turnover to get a positive commercial result on a specially formed group of gold deposits, in which individual field development is unprofitable. A small production volume, combined with high capital and operating costs are objective reasons for the reduction in investment attractiveness of the deposits which have reserves of gold of 50%, equipped with a mobile processing complex with deep processing technology on highly liquid commodity products on site. An economic-mathematical model was devised to determine the rational placement of the processing capacity of the group.A simulation was conducted and an economic evaluation was performed on the effectiveness of investments in individual and group mining projects. The simulation results show that the joint exploitation of the reserves of the group of deposits, the internal rate of return on investments exceed the rate of return of funds to the bank deposit, the return on investment is above the level of inflation. The group project complies with the strategic line of small mining companies in terms of cost recovery terms, availability of financial sources to cover expenses, provision of stable means of income and obtaining competitive advantage.

  14. Paragenesis And Evolution Of The Hydrothermal Bacuri Iron Oxide-copper-gold Deposit, Carajás Province (pa)

    OpenAIRE

    De Melo G.H.C.; Monteiro L.V.S.; Moreto C.P.N.; Xavier R.P.; Da Silva M.A.D.

    2014-01-01

    The Bacuri copper deposit is located about 9 km east of the world-class Sossego iron oxide-copper-gold deposit in the Carajás Province. It is hosted by the ca. 2.84 Ga Serra Dourada granite, the Bacuri Porphyry, and subordinated gabbro. The Bacuri deposit is situated within the regional-scale, WNW-ESE-trending ductile Canaã shear zone, characterized by early albite, scapolite-magnetite, potassium feldspar and biotite-scapolite-magnetite hydrothermal alteration zones. Copper mineralization was...

  15. Plasmonic Gold Helices for the visible range fabricated by oxygen plasma purification of electron beam induced deposits

    CERN Document Server

    Haverkamp, Caspar; Jäckle, Sara; Manzoni, Anna; Christiansen, Silke

    2016-01-01

    Electron beam induced deposition (EBID) currently provides the only direct writing technique for truly three-dimensional nanostructures with geometrical features below 50 nm. Unfortunately, the depositions from metal-organic precursors suffer from a substantial carbon content. This hinders many applications, especially in plasmonics where the metallic nature of the geometric surfaces is mandatory. To overcome this problem a post-deposition treatment with oxygen plasma at room temperature was investigated for the purification of gold containing EBID structures. Upon plasma treatment, the structures experience a shrinkage in diameter of about 18 nm but entirely keep their initial shape. The proposed purification step results in a core-shell structure with the core consisting of mainly unaffected EBID material and a gold shell of about 20 nm in thickness. These purified structures are plasmonically active in the visible wavelength range as shown by dark field optical microscopy on helical nanostructures. Most no...

  16. Simulation of rock mass balance of two typical altered rocks in Wulong gold deposit of Liaoning, China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Wulong gold deposit hosted in granite and fine-grained diorite dikes, is a typical gold deposit of quartz vein type. Granite and fine-grained diorite dikes in the ore deposit were altered by metallogenic fluid.Based on the altered zoning, the samples of petrochemistry were collected and major and trace elements were analyzed systematically. Calculation of rock mass balance shows that the major elements (SiO2, K2 O, P2O5,Fe2 O3) in the two typical altered rocks are clearly added into the altered system, and that trace elements (V,Y, Zr, Ni, Co, Sr) assume an increasing and decreasing tendencies in the altered granite and altered diorite dike, respectively. The fluid/rock ratios are 30.17-181.00 and 115.44-692.67 respectively for altered granite and altered diorite dike, they have profoundly effects on metallogenesis.

  17. 胶东金青顶金矿床成矿流体来源的黄铁矿微量元素及He-Ar同位素证据%Trace element and He-Ar isotopic evidence of pyrite for the source of oreforming fluids in the Jinqingding gold deposit, eastern Shandong Province

    Institute of Scientific and Technical Information of China (English)

    张运强; 李胜荣; 陈海燕; 张秀宝; 周起凤; 崔举超; 宋玉波; 郭杰

    2012-01-01

    The Jinqingding gold deposit with identified reserves of more than 50t is currently the largest lode gold deposit in terms of single vein gold resources and is also a superlarge gold deposit located in the middle part of the Muping- Rushan gold belt in Jiaodong; nevertheless, the genetic type and source of ore-forming fluids in the gold deposit constitute a problem that needs urgent solution. A study of trace elements and REE compositions and features of gold-bearing pyrite from No. II ore body of the Jinqingding gold deposit reveals that the pyrite displays hydrothermal characteristics with Co/Ni ratios from 2.317 to 11.734 (7.17 on average). The HFSE indicates that the ore-forming fluid originally belonged to the F-rich system and generally evolved into the Cl- rich system at the chief metallogenic stage, and the distribution patterns of REE shows that the source of matallogenic materials was not mainly from Mesozoic Kunyunshan monzonitic granite. According to an analysis of the characteristic parameters (3He/4He =0.1-2.2 Ra (0.60 Ra on average)),40Ar/36Ar =462.7-1507.5 (831 on average), it is considered that the source of matallogenic materials was mainly derived from the lower crust and was contaminated by meteoric water during the intrusion, and the mantle fluids were involved in the metallogenic process.%金青顶金矿床是目前国内最大的石英单脉型金矿,其金储量超过50 t,规模为大型.对该矿床成矿流体性质和来源的研究十分必要.笔者通过Ⅱ号矿体主要载金矿物黄铁矿微量元素的研究发现,其Co/Ni为2.317~11.734(平均7.17),显示主要为热液成因;高场强元素(HFSE)特征显示,成矿早期以富F流体为主,主成矿期以富C1流体为主;稀土配分模式显示成矿物质并不是直接来源于围岩昆嵛山二长花岗岩.对黄铁矿流体包裹体He、Ar同位素特征的研究表明,3He/4He、40Ar/36Ar分别为0.1~2.2 Ra(平均值0.60 Ra),462.7~1 507.5(平均值831),显示成

  18. Placer Gold Composition and Provenance Studies in the Kuznetskiy Alatau and Western Sayan, South-East Siberia: Results of Field Trip, Summer 2014

    Directory of Open Access Journals (Sweden)

    G. J.G. Paxman

    2015-03-01

    Full Text Available This article presents the results of a study of gold samples obtained by students during a practical field trip in the summer of 2014. Placer gold samples retrieved from four rivers in southeast Siberia (Khakassia and Tyva territories by panning and sluicing were described and analyzed compositionally by Scanning Electron Microscopy. There is evidence from grain flattening and morphology for significant variations in gold transport distance, both within and between sample locations. The composition and texture of gold is compared to similar studies in the Yukon, and it is inferred that most of the placer gold in the region originated from orogenic lode sources. This orogenic gold is of Devonian to Carboniferous age. There is also evidence for a contribution from igneous intrusion-related bedrock gold, which is supported by the presence of granite, granodiorite and sienite intrusions of Devonian age. There is scope for further study, since relatively few grains were analyzed here. In addition, if compositional data of the prospective primary gold deposits can be obtained, there would be potential for more precise determination of provenance.

  19. Enhanced formic acid oxidation on polycrystalline platinum modified by spontaneous deposition of gold. Fourier transform infrared spectroscopy studies

    Science.gov (United States)

    Cappellari, Paula S.; García, Gonzalo; Florez-Montaño, Jonathan; Barbero, Cesar A.; Pastor, Elena; Planes, Gabriel A.

    2015-11-01

    Formic acid and adsorbed carbon monoxide electrooxidation on polycrystalline Pt and Au-modified Pt surfaces were studied by cyclic voltammetry, lineal sweep voltammetry and in-situ Fourier transform infrared spectroscopy techniques. With this purpose, a polycrystalline Pt electrode was modified by spontaneous deposition of gold atoms, achieving a gold surface coverage (θ) in the range of 0 ≤ θ ≤ 0.47. Results indicate the existence of two main pathways during the formic acid oxidation reaction, i.e. dehydration and dehydrogenation routes. At higher potentials than 0.5 V the dehydrogenation pathway appears to be the operative at both Pt and Au electrodes. Meanwhile, the dehydration reaction is the main pathway for Pt at lower potentials than 0.5 V. It was found that reaction routes are easily tuned by Au deposition on the Pt sites responsible for the formic acid dehydration reaction, and hence for the catalytic formation of adsorbed carbon monoxide. Gold deposition on these Pt open sites produces an enhanced activity toward the HCOOH oxidation reaction. In general terms, the surface inhibition of the reaction by adsorbed intermediates (indirect pathway) is almost absent at gold-modified Pt electrodes, and therefore the direct pathway appears as the main route during the formic acid electrooxidation reaction.

  20. Plasmonic gold helices for the visible range fabricated by oxygen plasma purification of electron beam induced deposits

    Science.gov (United States)

    Haverkamp, Caspar; Höflich, Katja; Jäckle, Sara; Manzoni, Anna; Christiansen, Silke

    2017-02-01

    Electron beam induced deposition (EBID) currently provides the only direct writing technique for truly three-dimensional nanostructures with geometrical features below 50 nm. Unfortunately, the depositions from metal-organic precursors suffer from a substantial carbon content. This hinders many applications, especially in plasmonics where the metallic nature of the geometric surfaces is mandatory. To overcome this problem a post-deposition treatment with oxygen plasma at room temperature was investigated for the purification of gold containing EBID structures. Upon plasma treatment, the structures experience a shrinkage in diameter of about 18 nm but entirely keep their initial shape. The proposed purification step results in a core-shell structure with the core consisting of mainly unaffected EBID material and a gold shell of about 20 nm in thickness. These purified structures are plasmonically active in the visible wavelength range as shown by dark field optical microscopy on helical nanostructures. Most notably, electromagnetic modeling of the corresponding scattering spectra verified that the thickness and quality of the resulting gold shell ensures an optical response equal to that of pure gold nanostructures.

  1. Shear Alteration, Mass Transfer and Gold Mineralization: An Example from Jiaodong Ore Deposit Concentrating Area, Shandong, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Taking the gold ore deposit concentrating area of Jiaodong area in Shandong, China for an example, based on geological analysis, and applying Gresens' equation, Grant's isocon diagram and O'hara microelement calculation method, a thorough study on shear alteration, mass transfer and gold mineralization was carried out. The authors also made mathematic simulation and geochemical analysis. The work reveals temporal-spatial changing regularities of temperature field and velocity field of fluids, and also reveals fluid transport-chemical reaction coupling metallogenic dynamics of the Jiaojia gold ore concentrating area. During shear-alteration process of the Jiaodong gold ore concentrating area, all kinds of components transferred with different amounts, fluid-rock ratio was rather high and volume strain was of dilation type. Fast flow of ore-forming fluid favors the occurrence of mixed fluid. Shear-fractured zones are places where there was strong transportationreaction coupling mineralization. Ore bodies were located in dilation space of shear structure where there was the greatest fluid flux. After the emplacement of the rock body, a convex heat field was formed around the rock body. It is one of the main metallogenic forces. The major reason for mineralization is the mobilization, migration and enrichment of ore-forming elements induced by shear compressive-extensional tectonism. Inclusion gold dominant Iow-grade ores were formed in the early ore-forming stage, while high-grade ores, which contained fissure gold and polymetallic veinlets, were formed in late ore-forming stage.

  2. Sr Isotope Constraints on the Age and Source of Ore—Forming Materials of Gold Deposits,Southwestern Hunan

    Institute of Scientific and Technical Information of China (English)

    彭建堂; 戴塔根; 等

    2000-01-01

    We have measured Rb and Sr concentrations in fluid inclusions of quartz in gold deposits,southwestern Hunan,The Rb-Sr isochron ages of 435±9Ma and 412±33Ma are respectively determined,revealing that gold mineralization in this area took place in the Caledonian period rather than in the Wuling-Xuefeng period as traditionalyy considered.Sr isotope geochemistry of the hydrothermal fluid indicates that the ore-forming materials are of crust origin,derived largely from the ore-hositng strata rather than from the basic dikes.

  3. Possible genetic link between I-type granite and orogenic gold deposits in Egypt (metamorphic-magmatic interaction?)

    Science.gov (United States)

    Abd El Monsef, Mohamed

    2015-04-01

    The orogenic gold deposits are a distinctive type of deposits that revealed unique temporal and spatial association with an orogeny. Where, the system of gold veins and related ore minerals was confined to hydrothermal solutions formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and collisional orogens, with the respect to ongoing deep-crustal, subduction-related thermal processes. In Egypt, most of vein-type and dyke-type gold mineralization are restricted to granitic rocks or at least near of granitic intrusion that seems to have had an important influence on gold mineralization. Shear zone-related, mesothermal gold deposits of Fatira and Gidami mines in the northern Eastern Desert of Egypt are found within granitic bodies or at the contact between granites and metavolcanic rocks. The hosting-granitic rocks in Fatira and Gidami areas are mainly of granodioritic composition (I-Type granite) which is related to calc-alkaline magmatic series. However, Fatira granitoids were developed within island arc tectonic settings related to mature island arc system (Late-orogenic stage), at relatively low temperature (around 660° C) and medium pressure between (5 - 10 Kbar). On the other hand, Gidami granitoids were developed during the collision stage in continental arc regime related to active continental margin (Syn-orogeny), which were crystallized at relatively high temperature (700-720° C) and low pressure (around 0.1 Kbar). The ore mineralogy includes pyrite, chalcopyrite, sphalerite, covellite, ilmenite, goethite ± pyrrhotite ± pentlandite ± galena ± molybdenite. Native gold is detected only in Gidami mineralization as small inclusions within pyrite and goethite or as tiny grains scattered within quartz vein (in close proximity to the sulfides). In Fatira deposits, it is detected only by microprobe analysis within the crystal lattice of pyrite and jarosite. Fluid inclusions study for the mineralized

  4. Auriferous Quartz Veins from the Dongping Gold Deposit,NW Hebei Province and Metallogenesis—Fluid Inclusion Rb—Sr Isochron Evidence

    Institute of Scientific and Technical Information of China (English)

    莫测辉; 王秀璋; 等

    1996-01-01

    The Dongping gold deposit,situated on the northern margin of the North China Platform,is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies.It is hosted in the inner contact zone of an alkaline intrusion which was intruded in to Archean metamorphic rocks and was formed not later than the Hercynian period.Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103±4Ma ,indicating that the gold deposit was formed in the Yenshanian period,86Sr/86Sr source tracing shows the ore-forming materials came dominantly from alkaline intrusions.These results combined with other isotope and REE data,suggest that the Dongping gold deposit is not a traditiolal magmatic hydrothermal deposit,but a reworked hydrothermal deposit related to heated and evolved meteoric water.

  5. Control of favorable lithology on Jinlongshan micro-fine disseminated gold deposits, southern Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    赵利青; 冯钟燕

    2002-01-01

    Jinlongshan gold orebelt, a newly discovered one in sedimentary rock region in southern Qinling Mountains, is mainly located in upper Devonian and lower Carboniferous calcareous siltstone and argillic silty limestone of later Paleozoic era. Typical disseminated gold mineralization occurred in calcareous siltstone, which is major host rock and mainly composed of silt (SiO2 mostly varies from 38% to 73%) and calcite (CaO mostly varies from 10% to 25%). Pyrite created by living beings in Nanyangshan formation may be poor in gold. Faults and favorable layers jointly control disseminated gold mineralization. The significance of this opinion is very great for gold exploration.

  6. Late-Hercynian intrusion-related gold deposits: An integrated model on the Tighza polymetallic district, central Morocco

    Science.gov (United States)

    Éric, Marcoux; Khadija, Nerci; Yannick, Branquet; Claire, Ramboz; Gilles, Ruffet; Jean-Jacques, Peucat; Ross, Stevenson; Michel, Jébrak

    2015-07-01

    Gold have been recently recognized in the Tighza (formerly Jebel Aouam) district, in the Hercynian belt of central Morocco. This district has long been known for its W mineralization, as well as major Pb-Ag-Zn, and minor Sb-Ba deposits, all geographically associated with late-Hercynian calc-alkaline magmatism. Gold mineralization in the district is mainly hosted by thick W-Au quartz veins located around the "Mine granite" small granitic plug. Within the veins, gold grade is highest (up to 70 g/t) close to the granite but rapidly decreases going outward from the granite, defining a perigranitic zoning. Anomalous gold grades have also been measured in hydrothermal skarn layers close to two other granitic plugs (Kaolin granite and Mispickel granite), associated with disseminated As-Fe sulfides. The paragenetic sequence for the W-Au quartz veins shows three stages: (1) an early oxidized stage with wolframite-scheelite associated with early quartz (Q1), (2) an intermediate Bi-As-Te-Mo-Au sulfide stage with loellingite, bismuth minerals and native gold with a later quartz (Q2), restricted to a narrow distance from the granite, and (3) a late lower temperature As-Cu-Zn-(Pb) stage with abundant massive pyrrhotite, arsenopyrite and sphalerite, locally forming independent veins ("pyrrhotite vein"). Both Q1 hyaline and Q2 saccharoidal gold-bearing quartz display aqua-carbonic fluids with minor H2S and Cu and an homogeneous composition (81 mole% H2O, 18 mole% CO2 and about 1 mole% NaCl). The trapping pressure is estimated to 1.5-2 kbar with temperature ranging from 300 to 350 °C. Q1 inclusions have exploded indicating an uplift of the Tighza block, that lead to saccharoidal Q2 quartz deposition with multiphase NaCl-saturated fluid inclusions. 40Ar/39Ar dating demonstrates that the "Mine granite", tungsten skarnoid, scheelite-molybdenite veins, and very likely gold-bearing veins are coeval, emplaced at 286 ± 1 Ma. Multiple and widespread metal sources are indicated by

  7. In-Plane Structure of Underpotentially Deposited Copper on Gold (111) Determined by Surface EXAFS (Extended X-Ray Absorption Fine Structure).

    Science.gov (United States)

    1988-01-28

    D-Al 263 INN-PLANE STRUCTURE OF UNDERPOTENTIALLY DEPOSITED COPPER /. ON GOLD (Iii) DET (U) PUERTO RICO UNIV RIO PIEDRAS DEPT OF PHVS I CS 0 R...051-0776 TECHNICAL REPORT #33 In-Plane Structure of Underpotentially Deposited Copper on Gold (111) Determined by Surface EXAFS by O.R. Melroy*, M.G...Strueture of Underpotentially Deposited Copper on Gold ( 11) determincd hv Surface EXAFS 0. R. Melroy*, N1. G. Samant, G. L. Borges. and J. G. Gordon

  8. Bacterial deposition of gold on hair: archeological, forensic and toxicological implications.

    Directory of Open Access Journals (Sweden)

    Genevieve Phillips

    Full Text Available BACKGROUND: Trace metal analyses in hair are used in archeological, forensic and toxicological investigations as proxies for metabolic processes. We show metallophilic bacteria mediating the deposition of gold (Au, used as tracer for microbial activity in hair post mortem after burial, affecting results of such analyses. METHODOLOGY/PRINCIPAL FINDINGS: Human hair was incubated for up to six months in auriferous soils, in natural soil columns (Experiment 1, soils amended with mobile Au(III-complexes (Experiment 2 and the Au-precipitating bacterium Cupriavidus metallidurans (Experiment 3, in peptone-meat-extract (PME medium in a culture of C. metallidurans amended with Au(III-complexes (Experiment 4, and in non-auriferous soil (Experiment 5. Hair samples were analyzed using scanning electron microscopy, confocal microscopy and inductively coupled plasma-mass spectrometry. In Experiments 1-4 the Au content increased with time (P = 0.038. The largest increase was observed in Experiment 4 vs. Experiment 1 (mean = 1188 vs. 161 microg kg(-1, Fisher's least significance 0.001. The sulfur content, a proxy for hair metabolism, remained unchanged. Notably, the ratios of Au-to-S increased with time (linear trend P = 0.02 and with added Au and bacteria (linear trend, P = 0.005, demonstrating that larger populations of Au-precipitating bacteria and increased availability of Au increased the deposition of Au on the hair. CONCLUSION/SIGNIFICANCE: Interactions of soil biota with hair post mortem may distort results of hair analyses, implying that metal content, microbial activities and the duration of burial must be considered in the interpretation of results of archeological, forensic and toxicological hair analyses, which have hitherto been proxies for pre-mortem metabolic processes.

  9. Preliminary protein corona formation stabilizes gold nanoparticles and improves deposition efficiency

    Science.gov (United States)

    Luby, Alexandra O.; Breitner, Emily K.; Comfort, Kristen K.

    2016-08-01

    Due to their advantageous characteristics, gold nanoparticles (AuNPs) are being increasingly utilized in a vast array of biomedical applications. However, the efficacy of these procedures are highly dependent upon strong interactions between AuNPs and the surrounding environment. While the field of nanotechnology has grown exponentially, there is still much to be discovered with regards to the complex interactions between NPs and biological systems. One area of particular interest is the generation of a protein corona, which instantaneously forms when NPs encounter a protein-rich environment. Currently, the corona is viewed as an obstacle and has been identified as the cause for loss of application efficiency in physiological systems. To date, however, no study has explored if the protein corona could be designed and advantageously utilized to improve both NP behavior and application efficacy. Therefore, we sought to identify if the formation of a preliminary protein corona could modify both AuNP characteristics and association with the HaCaT cell model. In this study, a corona comprised solely of epidermal growth factor (EGF) was successfully formed around 10-nm AuNPs. These EGF-AuNPs demonstrated augmented particle stability, a modified corona composition, and increased deposition over stock AuNPs, while remaining biocompatible. Analysis of AuNP dosimetry was repeated under dynamic conditions, with lateral flow significantly disrupting deposition and the nano-cellular interface. Taken together, this study demonstrated the plausibility and potential of utilizing the protein corona as a means to influence NP behavior; however, fluid dynamics remains a major challenge to progressing NP dosimetry.

  10. Paper supports in electrocatalysis. Weak contact catalysis with seed-mediated grown gold nanoparticle deposits

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Munetaka; Nakashima, Daisuke [Department of Material Chemistry, Graduate School of Engineering, Kyoto University (Japan); Cummings, Charles Y.; Marken, Frank [Department of Chemistry, University of Bath (United Kingdom)

    2011-01-15

    Paper surfaces (Whatman filter papers, Kimwipes, and Japanese Washi papers) were employed as support for gold nanoparticles (AuNPs) deposited by the seed-mediated growth method. The AuNP-modified paper or textile was brought into 'weak' (or non-permanent) contact with a glassy carbon electrode and immersed into aqueous electrolyte media. Electrochemical responses for the Fe(CN){sub 6}{sup 4-}/Fe(CN){sub 6}{sup 3-} redox system in 0.1 M phosphate buffer (pH 7.0) and 1.0 M KCl solutions were investigated by voltammetry and impedance methods. Even for weakly contacted AuNP catalysts of relatively low density faster electron transfer was observed. Particle sizes of at least 20 nm diameter were required. There was no permanent contact from AuNP catalysts to the electrode and the process was therefore termed 'weak contact catalysis'. The method is proposed as a rapid and novel catalyst screening tool with potential applications in fuel cell and sensor technologies. (author)

  11. The Characterization of Al Bond Pad Surface Treatment in Electroless Nickel Immersion Gold (ENIG Deposition

    Directory of Open Access Journals (Sweden)

    M. K. M. Arshad

    2007-01-01

    Full Text Available This study reports a number of experiments that were designed to characterize aluminum bond pad surfaces prior to electroless nickel immersion gold (ENIG. In the ENIG process, aluminum bond pads need special treatment to achieve successful nickel deposition and provide reliable interconnection of under bump metallurgy in advanced packaging. During this treatment process, the aluminum pad was cleaned, activated and then coated with a layer of zinc. Systematic study was carried out to determine the best parameters, through multiple and various exposure times of the zincation process and zincation solution concentration effect on the Ni/Au surface roughness and aluminum dissolution rate on the bond pad during multiple zincation process. The ball shear strength was evaluated between eutectic 37Pb/63Sn solder ball and under bump metallurgy (UBM interfaces across multiple zincation process. Scanning Electron Microscope (SEM, Energy Dispersive X-Ray (EDX, Atomic Force Microscopy (AFM, Focused Ion Beam (FIB and ball shear tester were used as analytical tools. The results suggest that the multiple zincation process consistently produces a smoother surface of ENIG UBM and consequently provides a better shear strength.

  12. Amperometric Immunosensor Based on a Protein A/Deposited Gold Nanocrystals Modified Electrode for Carbofuran Detection

    Directory of Open Access Journals (Sweden)

    Xia Sun

    2011-12-01

    Full Text Available In this paper, an amperometric immunosensor modified with protein A/deposited gold nanocrystals (DpAu was developed for the ultrasensitive detection of carbofuran residues. First, DpAu were electrodeposited onto the Au electrode surface to absorb protein A (PA and improve the electrode conductivity. Then PA was dropped onto the surface of DpAu film, used for binding antibody Fc fragments. Next, anti-carbofuran monoclonal antibody was immobilized on the PA modified electrode. Finally, bovine serum albumin (BSA was employed to block the possible remaining active sites avoiding any nonspecific adsorption. The fabrication procedure of the immunosensor was characterized by electrochemical impedance spectroscopy (EIS and cyclic voltammetry (CV, respectively. With the excellent electroconductivity of DpAu and the PA’s oriented immobilization of antibodies, a highly efficient immuno-reaction and detection sensitivity could be achieved. The influences of the electrodeposition time of DpAu, pH of the detection solution and incubation time on the current response of the fabricated immunosensor were investigated. Under optimized conditions, the current response was proportional to the concentration of carbofuran which ranged from 1 to 100 ng/mL and 100 ng/mL to 100 μg/mL. The detection limit was 0.1924 ng/mL. The proposed carbofuran immnuosensor exhibited high specificity, reproducibility, stability and regeneration performance, which may open a new door for ultrasensitive detection of carbofuran residues in vegetables and fruits.

  13. Amperometric immunosensor based on a protein A/deposited gold nanocrystals modified electrode for carbofuran detection.

    Science.gov (United States)

    Sun, Xia; Zhu, Ying; Wang, Xiangyou

    2011-01-01

    In this paper, an amperometric immunosensor modified with protein A/deposited gold nanocrystals (DpAu) was developed for the ultrasensitive detection of carbofuran residues. First, DpAu were electrodeposited onto the Au electrode surface to absorb protein A (PA) and improve the electrode conductivity. Then PA was dropped onto the surface of DpAu film, used for binding antibody Fc fragments. Next, anti-carbofuran monoclonal antibody was immobilized on the PA modified electrode. Finally, bovine serum albumin (BSA) was employed to block the possible remaining active sites avoiding any nonspecific adsorption. The fabrication procedure of the immunosensor was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. With the excellent electroconductivity of DpAu and the PA's oriented immobilization of antibodies, a highly efficient immuno-reaction and detection sensitivity could be achieved. The influences of the electrodeposition time of DpAu, pH of the detection solution and incubation time on the current response of the fabricated immunosensor were investigated. Under optimized conditions, the current response was proportional to the concentration of carbofuran which ranged from 1 to 100 ng/mL and 100 ng/mL to 100 μg/mL. The detection limit was 0.1924 ng/mL. The proposed carbofuran immnuosensor exhibited high specificity, reproducibility, stability and regeneration performance, which may open a new door for ultrasensitive detection of carbofuran residues in vegetables and fruits.

  14. Surface plasmon sensor with gold film deposited on a two-dimensional colloidal crystal

    Science.gov (United States)

    Li, Yuanyuan; Sun, Jie; Wang, Li; Zhan, Peng; Cao, Zhishen; Wang, Zhenlin

    2008-08-01

    A sensor based on surface plasmon resonance (SPR) of plasmonic crystals fabricated via a colloidal-crystal-assisted templating method is studied. Plasmonic crystals are prepared by depositing a thin gold (Au) layer onto a two-dimensional array of polystyrene spheres self-assembled on a quartz substrate. The enhanced transmission as a result of the SPR of Au plasmonic crystals, which are immersed in different ambient liquids, are measured and compared with that of polystyrene (PS) microsphere templates of different sizes, both before and after removal of Au nanoprisms formed on the quartz substrate through pores among the spheres. It is found that the measured sensitivities exhibit a linear dependence on the refractive index of the surrounding medium and are linked to coupling effects between SPRs on the corrugated Au film and nanoislands. The feasibility of the SPR system in molecular monolayer detection is further demonstrated through a formation of alkanethiolate self-assembled monolayers on the Au film surface, which causes a 4 nm red-shift of the main SPR.

  15. Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

    Institute of Scientific and Technical Information of China (English)

    DU,Yong-Ling(杜永令); WANG,Chun-Ming(王春明)

    2002-01-01

    The cyclic voltammetry (CV) and the semidifferential anodic stripping voltanmetry (SdASV) were used for investigation of bismuth(Ⅲ) underpotential deposition (UPD) on gold electrode. Based on the excellent electrochemical properties of Au/Bi UPD system, a new method for determining bismuth (Ⅲ)was established. A solution of 0.1 mol/L HNO3 was selected as the supporting electrolyte. Factors affecting the Bi(Ⅲ) UPD and stripping steps were investigated and an opthmized analytical procedure was developed. The calibration plots for Bi(Ⅲ) concentration in the range 1.25 × 10-8-1.0 × 10-7 mol/L were obtained. The detection limit, calculated as three times the standard deviation of the analytical signal of 8.3×10-8 mol/L for a 90 s electrodeposition at 0.00 V (while the solution magnetically stirred at a speed of 300 rpm), was 7.5× 10-9 mol/ L. For8 successive determinations of 1.25 × 10-7 mol/L Bi(Ⅲ), the obtained RSD (relative standard deviation) was 0.4%. The developed method was applied to bismuth determining in medicine and urine samples. The analytical results were compared with that of atomic emission spectrometry (AES) method.

  16. In situ SIMS U-Pb dating of hydrothermal rutile: reliable age for the Zhesang Carlin-type gold deposit in the golden triangle region, SW China

    Science.gov (United States)

    Pi, Qiaohui; Hu, Ruizhong; Xiong, Bin; Li, Qiuli; Zhong, Richen

    2017-02-01

    The contiguous region between Guangxi, Guizhou, and Yunnan, commonly referred to as the Golden Triangle region in SW China, hosts many Carlin-type gold deposits. Previously, the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating. This paper reports the first SIMS U-Pb age of hydrothermal rutile crystals for the Zhesang Carlin-type gold deposit in the region. The hydrothermal U-bearing rutile associated with gold-bearing sulfides in the deposit yields an U-Pb age of 213.6 ± 5.4 Ma, which is within the range of the previously reported arsenopyrite Re-Os isochron ages (204 ± 19 to 235 ± 33 Ma) for three other Carlin-type gold deposits in the region. Our new and more precise rutile U-Pb age confirms that the gold mineralization was contemporaneous with the Triassic W-Sn mineralization and associated granitic magmatism in the surrounding regions. Based on the temporal correlation, we postulate that coeval granitic plutons may be present at greater depths in the Golden Triangle region and that the formation of the Carlin-type gold deposits is probably linked to the coeval granitic magmatism in the region. This study clearly demonstrates that in situ rutile U-Pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile.

  17. Pure CO2 fluids in the Sarekoubu gold deposit at southern margin of Altai Mountains in Xinjiang, West China

    Institute of Scientific and Technical Information of China (English)

    XU Jiuhua; DING Rufu; XIE Yuling; ZHONG Changhua; YUAN Xu

    2005-01-01

    Sarekoubu gold deposit occurs in metamorphosed acid volcanic rocks and volcaniclastic rocks of Devonian Kangbutiebao Formation along the southern margin of Altai Mountains in Xinjiang, West China. Pyritization, silici- fication and carbonatization are developed in wallrocks, and main gold mineralization stages are pyrite-quartz stage (Ⅱ) and polymetallic sulfide stage (Ⅲ). Primary fluid inclusions are often seen in main gold mineralization stages, which are almost pure CO2 liquid inclusions (LCO2) under room temperature with high densities of 0.85-1.07 g/cm3. CO2-rich inclusions (LCO2-LH2O) and H2O-rich inclusions (LH2O-LCO2) are subordinate. Fluid inclusions in stage Ⅰ(polymetallic sulfide stage) are more complex than in stage Ⅱ,containing CO2-CH4 system with -78.1--61.9℃of solid CO2 melting temperatures and -33.7--17.7℃ of partial homogenization temperatures. The trapping pressures of high densities are estimated to be 150-350 Mpa. Laser Raman microprobe was used to confirm the composition of pure CO2 liquid inclusions.δ13C values of CO2 inclusions range from -10.73‰ to -21.15‰, which are similar to some of fluids in the mantle-derived minerals that contain surface organic carbon bysubduction recycling. These characteristics differ from many hydrothermal gold deposits. CO2 fluids have a regional source related to post-collisional orogeny.

  18. Metallogenesis of superlarge gold deposits in Jiaodong region and deep processes of subcontinental lithosphere beneath North China Craton in Mesozoic

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Xinhua(周新华); YANG; Jinhui(杨进辉); ZHANG; Lianchang(张连昌)

    2003-01-01

    The study of ore-forming chronology indicates that the superlarge gold deposits in the Jiaodong region were formed in 120±10 Ma. Sr-Nd-Pb isotopic compositions from typical gold deposits suggest that ore-forming materials were derived from the multisources, mantle component was partly involved in mineralization, the deep dynamic processes are the major geological background of large-scale metallogenesis in the Jiaodong region in Mesozoic. The deep pro- cesses mainly include the effect of post deep-subduction of continental crust of the central orogen belt and the distant effect of subduction of the paleo-Pacific plate underneath the Eurasian continent. However, lithosphere thinning, crust-mantle interaction, crustal extension and formation of large-type ore-controlling structures would be the comprehensive consequences of the above- mentioned geodynamic processes in the region.

  19. 中国浅成低温热液金矿床%Epithermal gold deposits of China

    Institute of Scientific and Technical Information of China (English)

    裘愉卓; 涂光炽; Byron R. BERGER

    2008-01-01

    Epithermal gold deposits have been found mainly in eastern China and recently in the northern Xinjiang Region.They are grouped into four bolts based on their tectonic settings and belong to three mineralization episodes. They include:(1) the Cenozoic eastern Taiwan island are belt; (2) the Late Paleozoic North Xinjiang island arc bolt; (3) the Mesozoic continental margin bolt along the northern border of the Sino-Korean Craton; and (4) the Mesozoic continental margin belt of SE China coastal area. Most of the reviewed deposits are of low snlfidation type, three are of high sulfidation type, and one is of Au-Te type related to alkaline rock series. Except the Chinkuashih deposit, the largest gold deposit in China, the epithermal gold deposits in general are of less economic importance at present in the mainland of China. The total reserve of epithennal gold deposits discovered in eastern China is not compared with the huge volume of widespread subaerial volcanic rocks of Mesozoic age. Relatively old mineralization age, Mesozoic in eastern China and Late Paleozoic in North Xinjiang, is an apparent feature of epithermal gold deposits in the mainland of China. Based on the analyses of metallogenic condition and preservation in China, and the comparison with western USA and eastern Russia, a preliminary assessment on the potential of epithermal gold deposits of China has been presented. Northern Xinjiang may be potentially significant for finding epithermal gold deposits.%浅成低温热液金矿床在中国传统上称为陆相火山岩型金矿床,主要发现在中国东部,后来在北疆地区也有新的发现.根据产出的大地构造背景,它们集中分布在3个带,并分属于3个成矿时期.它们包括:(1)新生代台湾东部岛弧带;(2)晚古生代北疆岛弧带;(3)中生代沿中朝克拉通北界的大陆边缘带;(4)中生代中国东南沿海地区的大陆边缘带.绝大多数矿床是低硫化型的,只有3个是高硫化型的,另有1个是

  20. Reworking Intensity—A Key Factor Leading to the Formation of Superlarge Gold Deposits in Greenstone Belts and Metamorphosed Microclastic Rocks in China

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 陆德复; 等

    1999-01-01

    The greenstone belt and metamorphosed microclastic rock-type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies.Sedimentation.regional metamorphism and mineralization contributed a lot to the formation of the deposits,so did remelting magmatic process to some deposits,but the deposits were finally formed by reworking processes.The key factor leading to the formation of superlarge gold deposits is the reworking intensity,which for superlarge gold deposits is reflected by the large-scale reworked source rocks and even ore materials of various sources,strongly oxidized ore-forming fluids with a long and repeated active history and stable geothermal heat current.The factor which decides the reworking intensity is the network consisting of structures of different classes.

  1. Removal of internally deposited gold by 2,3-dimercaptopropane sodium sulphonate (Dimaval).

    OpenAIRE

    Gabard, B.

    1980-01-01

    1 Orally administered 2,3-dimercaptopropane sodium sulphonate (DMPS, Dimaval) reduced the concentration of gold in rats treated with Auro-Detoxin and increased the urinary excretion of the metal. 2 In a long-term experiment, DMPS decreased significantly the concentration of gold in the kidneys and in the skin and increased it in plasma. 3 DMPS appears to be of interest as a possible antidote to gold, which could replace the more toxic 2,3-dimercaptopropanol (BAL).

  2. Rare Earth Elements Geochemistry of Laowan Gold Deposit in Henan Province: Trace to Source of Ore-Forming Materials

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The compositions of REE in quartz and pyrite from the main stage of the Laowan gold deposit in Henan Province and that in quartz from Laowan granite were determined by inductively coupled plasma-mass-spectrometry (ICP-MS) to trace the source of ore-forming materials. Meanwhile, the REE compositions of the deposit ore, granite and metamorphic wall rock were also considered for comparative studies in detail. The range of ∑REE of quartz and pyrite from the deposit ores is 4.18×10-6~30.91×10-6, the average of ∑REE is 13.39×10-6, and the average of ∑REE of quartz in the Laowan granite is 6.68×10-6. There is no distinct difference of REE parameters between the deposit ore quartz and granite quartz. The quartz in gold deposit has the same REE particular parameters as quartzes from Laowan granite, such as δEu, δCe, (La/Yb)N and (La/Sm)N, partition degree of LREE to HREE, especially, the chondrite-normalized REE patterns, but no similarity to those from metamorphic wall rock, which shows that ore-forming hydrothermal fluid is mainly the fluid coming from the Laowan granite magma, rather than metamorphic fluid. Meanwhile, comparison studies on REE features between minerals from the deposit ores and related geological bodies in the deposit show that REE characteristics of minerals can serve as an indicator of ore-forming fluid properties and sources, while the REE characteristics of the bulk samples (such as deposit ores, granites and wall rocks) can not trace the source of the ore-forming materials exactly.

  3. Study on the occurrence mode of invisible gold in pyrite of Muyanggou gold deposit%牧羊沟金矿黄铁矿中不可见金的赋存状态

    Institute of Scientific and Technical Information of China (English)

    李英; 郭月琴

    2012-01-01

    不可见金存在于许多金矿的黄铁矿中.以牧羊沟金矿为例,对黄铁矿中不可见金的存在形式进行了多种实验方法研究.化学分析和扫描电子显微镜实验结果表明,黄铁矿中不可见金大部分是自然金.分步溶解实验也证实,黄铁矿中的不可见金以自然金的形式存在.%Invisible gold occurs in pyrite of many gold deposits in the world. With Muyanggou gold deposit as example , the occurrence mode of invisible gold in pyrite was examined with many methods. Poly-spot chemical analysis and SEM examination of invisible gold in pyrite showed that most of the invisible gold was native gold. Invisible gold in pyrite do exist as native gold by step-dissolution experiments.

  4. Electroless selective deposition of gold nano-array for silicon nanowires growth

    Directory of Open Access Journals (Sweden)

    Ruiz-Gomes E.

    2014-01-01

    Full Text Available Nanopatterns of gold clusters on a large surface of oriented Si(111 substrates, from the galvanic displacement of gold salt (via the spontaneous reduction of AuCl4 -, are demonstrated in this work. The Si substrate is patterned by Focused Ion Beam (FIB prior to being dipped in a gold solution. Here, we show that these patterns lead to successful control of the position and size of gold clusters. Sequential patterning reveals a powerful maskless alternative to surface preparation prior to Si nanowire growth

  5. Tourmaline from the Archean G.R.Halli gold deposit, Chitradurga greenstone belt, Dharwar craton (India):Implications for the gold metallogeny

    Institute of Scientific and Technical Information of China (English)

    Susmita Gupta; M. Jayananda; Fareeduddin

    2014-01-01

    Tourmaline occurs as a minor but important mineral in the alteration zone of the Archean orogenic gold deposit of Guddadarangavanahalli (G.R.Halli) in the Chitradurga greenstone belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli gold deposit as (a) clusters of very fine grained aggregates which form a minor constituent in the matrix of the altered metabasalt (AMB tourmaline) and (b) in quartz-carbonate veins (vein tourmaline). The vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as (i) albite-tourmaline-ankerite-quartz veins (vein-1 tourmaline) and (ii) albite-tourmaline-calcite-quartz veins (vein-2 tourmaline). Both the AMB tourmaline and the vein tourmalines (vein-1 and vein-2) belong to the alkali group and are clas-sified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tour-malines are unzoned. Mineral chemistry and discrimination diagrams reveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the vein tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tour-malines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-à-vis gold mineralization is spatially linked to the juvenile magmatic accretion (2.56e2.50 Ga) east of the studied area in the western part of the eastern Dharwar craton.

  6. Metallogenesis of the Ertix gold belt, Xinjiang and its rela-tionship to Central Asia-type orogenesis

    Institute of Scientific and Technical Information of China (English)

    CHEN; Huayong; (

    2001-01-01

    [1]Rui, X.J., Zhu, S.H., Liu, K.J., The basic features and regional ore-forming model of Altay primary gold deposits in Xinjiang, Geology Reviews (in Chinese), 1993, 39(2): 138.[2]Wang, G. R., Explanation to the ‘Regional Geological Structures and Geological Evolution of Northern Xinjiang in China and Its Adjacent Regions’ (in Chinese), Wuhan: China University of Geosciences Press, 1996, 108.[3]Li, H.Q., Xie, C.F., Chang, H.L., Geochronology of Mineralization of Nonferrous and Precious Metallic Deposits in Northern Xinjiang (in Chinese), Beijing: Geological Publishing House, 1998, 264.[4]Groves, D. I., Goldfarb, R. J., Gebre-Mariam, M. et al., Orogenic gold deposits: a proposed classification in the context of their crustal distribution and relationship to other gold deposit types, Ore Geology Reviews, 1998, 13: 7. [5]Qiu, Y. M., Groves, D. I., Late Archean collision and delamination in the southwest Yilgarn craton: The driving force for Archean orogenic lode gold mineralization? Economic Geology, 1999, 94: 115.[6]Kerrich, R., Perspectives on genetic model for lode gold deposits, Mineral Deposits, 1993, 28: 362.[7]Chen, Y. J., Fluidization model for continental collision in special reference to study on ore-forming fluid of gold deposits in the eastern Qinling Mountains, China, Progress in Natural Sciences, 1998, 8(4): 385.[8]Chen, Y. J., Guo, G. J, Li, X., Metallogenic geodynamic background of Mesozoic gold deposits in granite-greenstone terrains of North China Craton, Science in China, Series D, 1998, 41(2): 113.[9]Chen, Y. J., Chen, H. Y., Liu, Y. L. et al., Progress and records in the study of endogenetic mineralization during collisional orogenesis, Chinese Science Bulletin, 2000, 45(1): 1.[10]Seltmann, R., Kampf, H., Moller, P., Metallogenesis in Collisional Orogens, Potsdam: GeoForschungs Zentrum Potsdam, 1994, 4-34.[11]Chen, Y. J., Yu, F., Wei, Q. Y. et al., Significance and current situation of study on

  7. Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

    Science.gov (United States)

    Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann

    2016-11-01

    The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (<0.8 atoms per formula unit (apfu)) of all tourmaline samples suggest that they precipitated from reduced, low-salinity fluids. Based on the similar chemical and boron isotope composition and the Re-Os age of molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of

  8. Analysis of the Ore-Controlling Structure of Ductile Shear Zone Type Gold Deposit in Southern Beishan Area, Gansu, Northwest China

    Institute of Scientific and Technical Information of China (English)

    Chen Bailin; Wu Ganguo; Ye Dejin; Liu Xiaochun; Shu Bin; Yang Nong

    2007-01-01

    The ductile shear zone-type gold deposit is a kind that both the ore-forming mechanism and ore-controlling factors are closely related to the ductile shear zone and its evolution. Ductile shear zone develops in Beishan area, Gansu of Northwest China, and develops especially well in the south belt.The controls of the ductile shear zone on gold deposits are as follows. (1) The regional distribution of gold deposits (and gold spots) is controlled by the ductile shear zone. (2) The ductile-brittle shear zone is formed in the evolution process of ductile shear zone and both are only ore-bearing structures and control the shape, attitude, scale, and distribution of mineralization zones and ore-bodies. (3) Compresso-shear ductile deformation results in that the main kind of gold mineralization is altered mylonite type and the main alteralization is metasomatic. (4) Ore-bearing fracture systems are mainly P-type ones, some D-type and R-type ones, but only individual R'-type and T-type ones. (5) Dynamic differentiation and dynamic metamorphic hydrothermal solution resulting from ductile deformation is one of the sources of ore-forming fluid of gold mineralization, and this is identical with that ore-forming materials are mainly from metamorphic rocks, and ore-forming fluid is mainly composed of metamorphic water, and with the fluid inclusion and geo-chemical characteristics of the deposit. (6) There is a negative correlation between the gold abundance and susceptibility anisotropy (P) of the altered mylonlte samples from the deposit, which shows that the gold mineralization is slightly later than the structural deformation. All above further expound the ore-forming model of the ductile shear zone type of gold deposits.

  9. Formation of gold mineralization in ultramafic alkalic magmatic complexes

    Science.gov (United States)

    Ryabchikov, I. D.; Kogarko, L. N.; Sazonov, A. M.; Kononkova, N. N.

    2016-06-01

    Study of mineral inclusions within alluvial gold particles of the Guli Complex (East Siberia) and findings of lode gold in rocks of the same intrusion have demonstrated that gold mineralization occurs in interstitions of both early high-magnesium rocks (dunite) and later alkalic and carbonatite rocks. In dunite the native gold occurs in association with Fe-Ni sulfides (monosulfide solid solution, pentlandite, and heazlewoodite). Formation of the gold-bearing alloys took place under a low oxygen potential over a broad range of temperatures: from those close to 600°C down to below 400°C.

  10. A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

    DEFF Research Database (Denmark)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle

    2017-01-01

    closure in 2014, having produced 10.67 t of gold. This study uses a combination of field investigation, petrography and U/Pb zircon and titanite geochronology to define a multistage hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed...... in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783–1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chloriteplagioclase- löllingite......-tourmaline-titanite), which is best developed in areas of exceptionally high gold grades. Aplite dykes dated to ca. 1762 Ma cross-cut the gold-quartz veins, providing a minimum age for mineralisation. A hydrothermal calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated...

  11. Constraints on mineralisation and hydrothermal alteration in the Nalunaq gold deposit, South Greenland

    DEFF Research Database (Denmark)

    Bell, Robin-Marie Fairbairn

    -and - medium grained amphibolite of the Nanortalik Nappe. Detailed petrographic and geochronological studies have revealed a multi-stage hydrothermal alteration system, with alteration pre-and post-dating gold mineralisation. The hydrothermal alteration records a transition from upper-amphibolite facies...... to lower greenschist facies metamorphic conditions, over a period of 40 million years. The development of the hydrothermal alteration can be correlated to deformation events in the wider Palaeoproterozoic Ketilidian Orogen. Petrographic thin section analysis has shown that sulphidation, saussuritization...... and hydrolysis reactions are important in locally precipitating gold, which may suggest an Au(HS)2- transport complex for gold. A c. 20 cm wide biotite-arsenopyrite alteration zone surrounds the gold-quartz veins locally, and denotes areas of high-gold grades. Implicit 3-Dimentional modelling has revealed...

  12. Lamellar multilayer hexadecylaniline-modified gold nanoparticle films deposited by the Langmuir-Blodgett technique

    Indian Academy of Sciences (India)

    Anita Swami; Ashavani Kumar; Murali Sastry

    2003-06-01

    Organization of hexadecylaniline (HDA)-modified colloidal gold particles at the air-water interface and the formation thereafter of lamellar, multilayer films of gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. Formation of HDA-capped gold nanoparticles is accomplished by a simple biphasic mixture experiment wherein the molecule hexadecylaniline present in the organic phase leads to electrostatic complexation and reduction of aqueous chloroaurate ions, capping of the gold nanoparticles thus formed and phase transfer of the now hydrophobic particles into the organic phase. Organization of gold nanoparticles at the air-water interface is followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique is monitored by quartz crystal microgravimetry, UVVis spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy.

  13. Fluid inclusion and noble gas studies of the Dongping gold deposit, Hebei Province, China: A mantle connection for mineralization?

    Science.gov (United States)

    Mao, J.; Li, Y.; Goldfarb, R.; He, Y.; Zaw, K.

    2003-01-01

    The Dongping gold deposit (>100 t Au) occurs about 200 km inboard of the northern margin of the North China craton. The deposit is mainly hosted by syenite of a middle Paleozoic alkalic intrusive complex that was emplaced into Late Archean basement rocks. Both groups of rocks are intruded by Late Jurassic to Early Cretaceous crustal-melt granite dikes and stocks, some within a few kilometers of the deposit. The gold ores were deposited during this latter magmatic period at about 150 Ma, a time that was characterized by widespread regional north-south compression that formed the east-west-trending Yanshan deformational belt. The ores include both the telluride mineral-bearing, low sulfide quartz veins and the highly K-feldspar-altered syenite, with most of the resource concentrated in two orebodies (1 and 70). Fluid inclusion microthermometry indicates heterogeneous trapping of low-salinity (e.g., 5-7 wt % NaCl equiv) fluids that varied from a few to 60 mole percent nonaqueous volatile species. Laser Raman spectroscopy confirms that the vapor phase in these inclusions is dominated by CO2, but may be comprised of as much as 9 mole percent H2S and 20 mole percent N2; methane concentrations in the vapor phase are consistently interaction of ore fluids with surrounding crustal rocks, which may have contributed additional He to the fluids. A mantle source for at least some of the components of the gold-forming fluid is consistent with upwelling of hot asthenosphere and erosion of as much as 100 to 150 km of cool Archean lithosphere beneath the craton during this time. The Dongping deposit is located along the 100-km-wide north-south gravity lineament, which marks the western border of the thinned crust. As both regional metamorphism of Mesoproterozoic and younger cover rocks, and widespread granite magmatism, also occurred at ca. 150 Ma, it is unclear as to whether one or both of these also contributed fluid and/or metals to the hydrothermal system. Importantly, these

  14. Fabrication of highly active and cost effective SERS plasmonic substrates by electrophoretic deposition of gold nanoparticles on a DVD template

    Energy Technology Data Exchange (ETDEWEB)

    Leordean, Cosmin; Marta, Bogdan; Gabudean, Ana-Maria; Focsan, Monica; Botiz, Ioan; Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro

    2015-09-15

    Highlights: • Simple and cost effective electrophoretic method to fabricate plasmonic substrates. • SERS performance at three different excitation laser lines. • Promising applicability in SERS based biosensing. - Abstract: In this work we present a simple, rapid and cost effective method to fabricate highly active SERS substrates. This method consists in an electrophoretic deposition of gold nanoparticles on a metallic nanostructured template of a commercial digital versatile disk (DVD). The negatively charged gold nanoparticles self-assemble on the positively charged DVD metallic film connected to a positive terminal of a battery, due to the influence of the electric field. When gold nanoparticles self-assembled on DVD metallic film, a 10-fold additional enhancement of Raman signal was observed when compared with the case of GNPs self-assembled on a polycarbonate DVD substrate only. Finite-difference time-domain simulations demonstrated that the additional electromagnetic field arising in the hot-spots created between gold nanoparticles and DVD metallic film induces an additional enhancement of the Raman signal. SERS efficiency of the fabricated plasmonic substrate was successfully demonstrated through detection of para-aminothiophenol molecule with three different excitation laser lines (532, 633 and 785 nm). The enhancement factor was calculated to be 10{sup 6} and indicates that plasmonic substrates fabricated through this method could be a promising platform for future SERS based sensors.

  15. Fluid immiscibility and gold deposition in the Birimian quartz veins of the Angovia deposit (Yaouré, Ivory Coast)

    Science.gov (United States)

    Coulibaly, Y.; Boiron, M. C.; Cathelineau, M.; Kouamelan, A. N.

    2008-02-01

    The Paleoproterozoic terranes (Birimian) of West Africa are well known to host numerous economic gold mineralizations. The Angovia gold mineralization is located in a brecciated and mylonitic zone within the Birimian greenstones. The sulfide-gold mineralization is mainly represented by gold associated with pyrite and chalcopyrite. A fluid inclusion study undertaken on mineralized quartz veins revealed the presence of aqueous-carbonic (CO 2-H 2O) fluids, the association of carbonic (CO 2) and early aqueous fluids, followed by later aqueous (H 2O-salt) and finally nitrogen-rich fluids. Entrapment of the initial homogeneous aqueous-carbonic fluids prior to fluid immiscibility depicts the evolution of the P-T conditions during the exhumation of the terranes after the peak of green-schist metamorphism. The CO 2 rich-fluid occurs especially in gold-bearing quartz, and are considered as the main evidence of the ore-forming process in the gold-bearing quartz veins. It is considered as a product of immiscibility of the CO 2-H 2O parent. The volatile fraction of carbonic and aqueous-carbonic fluid inclusions is dominated by CO 2, containing minor amounts of N 2, even smaller amounts of CH 4 and sporadically, H 2S. The aqueous-carbonic fluids have moderate salinity (3-10 wt.% eq. NaCl). Late aqueous and N 2 - (CH 4-CO 2) fluids are considered as later, unrelated to the main ore stage, and were trapped during the cooling of the hydrothermal system from 300 to 200 °C. The immiscibility has been favored by a strong pressure drop, the main trapping P-T conditions being 320-370 °C and 105-135 MPa. The mineralizing process is likely related to the immiscibility event, which was probably favored by the release of the fluid pressure after fracturing along the main shear zones. The ore process is likely to have occurred along the main shear zones or related secondary structures affected by cycling of the fluid pressure and quartz sealing-fracturing processes. The superimposed

  16. GEOLOGICAL CHARACTERS OF MAOJIADIAN GOLD DEPOSIT,LIAONING%辽宁省毛家店金矿床地质特征

    Institute of Scientific and Technical Information of China (English)

    刘殿忠

    2001-01-01

    毛家店金矿床位于冀东—凌南金矿成矿带的北东部,为受区域断裂构造燕山期黑云母花岗岩和八道河群变质杂岩所控制的含金石英脉型和硅钾蚀变岩型金矿床。区域上具有找矿前景。%Maojiadian Gold Deposit is located in Northeast part of Jidong-Linnan Gold ore Zone. The deposit is a Gold-bearing quartz vein type and Silicon-Potassium altered rock type Gold Deposit controlled by regional faults, Yanshan Period Mica granite and Badaohe group metamorphic complex. There is a potential for prospecting in the region.

  17. PALAEOEROSION SEDIMENTARY DISCONTINUITY TYPE GOLD DEPOSIT OF WESTERN GUANGXI%桂西古侵蚀沉积间断面型金矿床(续载)

    Institute of Scientific and Technical Information of China (English)

    陈开礼

    2001-01-01

    Palaeoerosion sedimentary discontinuity type gold deposit ismajor type gold deposit of western Guangxi. The metallogenic geological condition of this type gold deposit are analyzed, the genesis and metallogenic mechanism are also discussed, the author thinks this type gold ore mining and semlt easy, there are remarkable economic results, and the author proposes that the devolop capability should build up.%古侵蚀沉积间断面型金矿是桂西的主要金矿床类型。文章着重分析该类型金矿成矿地质条件,论述矿床成因及成矿机理,认为此类型金矿易采易冶,经济效益显著,建议加大开发力度。

  18. Study on the carbonate ocelli-bearing lamprophyre dykes in the Ailaoshan gold deposit zone, Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    HUANG; Zhilong(黄智龙); LIU; Congqiang(刘丛强); XIAO; Huayun(肖化云); HAN; Runsheng(韩润生); XU; Cheng(许成); LI; Wenbo(李文博); ZHONG; Kunming(钟昆明)

    2002-01-01

    Three carbonate ocelli-bearing lamprophyre dykes have been found in the Laowangzhai and Beiya gold orefields in the northern sector of the Ailaoshan gold deposit zone, Yunnan Province. Ocelli in the lamprophyre dykes are carbonates composed mainly of dolomite and calcite. Their trace elements, REE and C isotopic compositions are characteristic of carbonatite and the main mineral assemblages, major elements, trace elements and REE in the matrix are similar to those in the carbonate ocelli-barren lamprophyre dykes in the orefields, which are calc-alkaline lamprophyres that derived from the fertile mantle. The results indicate that the carbonate ocelli-bearing lamprophyre dykes in this area were produced at the time when the Himalayan lamprophyre magma evolved to a relatively late stage of silicate-carbonate liquid immiscibility. In the process of magmatic evolution there took place magmatic degassing with CO2 and H2O as the dominant released gases.

  19. Evolution of ore-forming fluids in the Sawayaerdun gold deposit in the Southwestern Chinese Tianshan metallogenic belt, Northwest China

    Science.gov (United States)

    Chen, Huayong; Chen, Yanjing; Baker, Michael J.

    2012-04-01

    The Sawayaerdun gold deposit was discovered in the early 1990s and is the largest orogenic-gold deposit in the Chinese Tianshan. Gold mineralization occurs in quartz veins, which are hosted in carbonaceous metasediments and controlled by faults and fractures. Three major hydrothermal events can be identified at Sawayaerdun: An early barren quartz vein stage, middle stage quartz veins with pyrite and gold mineralization and late carbonate (-quartz) veins. Fluid inclusion studies of quartz, pyrite and carbonate formed during the major hydrothermal stages show distinct changes in fluid, temperature, composition and redox conditions occurred during fluid evolution. Three types of fluid inclusions have been identified at Sawayaerdun: H2O + NaCl (L + V), H2O + NaCl + CO2 (L + V) and CO2 (L + V). Fluids trapped in early barren quartz have high temperatures (280-420 °C), low salinities (quartz formation, resulting in the generation of coexisting fluid inclusions with distinguishable vapor/liquid ratios and salinities. The compositional difference between fluids trapped in pyrite and quartz indicate fluid mixing may have occurred during the mineralization stage. The oxidized fluids, probably a mixture of meteoric water and fluids generated during water-host rock interaction, emerged into the ore-forming system to generate extensive metals precipitation. The fluid immiscibility and fluid mixing are most likely caused by pressure decrease during Late Paleozoic uplift and erosion in the Chinese Southern Tianshan area. Comparison of fluids between four major mineralization zones at Sawayaerdun indicate that zone II is similar to the most important zone IV and the order of similarity is probably zone II > XI > I, which could be applied to the future mineral exploration in this area.

  20. Rare Earth Element Geochemistry on Magmatic Rocks and Gold Deposits in Shizishan Ore-Field of Tongling, China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    REE geochemical characteristics of the magmatic rocks and gold deposits in Shizishan ore-field of Tongling were studied. Three types of the magmatic rocks have almost the same chondrite-normalized REE patterns, Eu and Ce anomalous values, and ΣREE, ΣLREE/ΣHREE regular changes, which indicates that their magmas come from the same source and their digenetic mechanism is fractional crystallization. In three gold deposits, the mineral ores and related altered rocks have similar chondrite-normalized REE patterns and sharp Eu positive anomalous values. The REE contents reduced from the magmatic rocks to skarnization or alteration magmatic rocks, skarn type ores, sulphide type ores, wall-rocks limestone or marble. The REE geochemical characteristics of the ores and related rocks show that primary fluids originated from magmatic differentiation in lower pressure of shallow crust, ore-forming hydrothermal solutions gained REE and mineralization elements further from leaching the magmatic rocks, then superimposed and reformed the limestones or marbles and deposited ore-forming material.

  1. Metalliferous deposits of the greater Helena mining region, Montana

    Science.gov (United States)

    Pardee, Joseph Thomas; Schrader, F.C.

    1933-01-01

    characterized by the accumulation of marine sediments and the later by mountain building and erosion. The later period began with folding and elevation in late Cretaceous or early Eocene time, followed by overthrust faulting and the intrusion of the Boulder batholith. Next, there ensued a period of crustal stability, during which erosion reduced the region to a surface of low relief and cut away at least 10,000 feet of strata in the area north of Helena. In Oligocene, Miocene, and Pliocene (?) time sediments composed of land waste and volcanic ash were deposited, and this event was followed by warping and faulting that elevated the present mountains. During Pliocene and Pleistocene time the mountains were maturely dissected, and in middle and late Pleistocene time local glaciers formed in the higher mountains and large valley glaciers invaded the extreme northern part of the region. The ore deposits include lodes and placers that have yielded gold, silver, lead, copper, and zinc to a value of at least $176,860,000. The placers were formed mostly during interglacial stages of the Pleistocene. They have been almost entirely exhausted. Most of the lodes are classified as regards age in two groups, an older and a younger. The older lodes are related in origin to the Boulder batholith or some of the neighboring intrusive granitic bodies and were probably formed during early Eocene time. The younger lodes were formed after dacite of probable Miocene age was erupted. They are possibly related in origin to some unexposed intrusive granitic rock. For convenience in description the region is divided into three parts districts north of Helena, districts in the Belt Mountains, and districts south of Helena. The districts north of Helena include a 50-mile stretch of the Continental Divide that forms a broad ridge surmounted with considerable areas of flat or gently sloping surface at a general altitude of 7,000 feet. Narrow valleys 1,000 to 2,000 feet deep are cut into this surface and lead

  2. The nature of gold in the Aitik Cu-Au deposit:implications for mineral processing and mine planning

    OpenAIRE

    Sammelin, Monika

    2011-01-01

    The Aitik mine is a large Cu-Au producer in Europe with an annual production of 28 million tons of ore and a planned expansion of production to 36 million tons of ore until year 2013. Large ongoing investments are done in the mine and a new processing plant is built to manage the capacity increase. The mine is situated 15 kilometers from the town Gällivare, in northern Norrbotten, Sweden. The ore is a large porphyry type deposit with low grades of disseminated copper (0,27 %) and gold (0,16 p...

  3. Remote Sensing Technology for Identification of Alteration Information of Gold Deposits in the Eastern Tianshan Area, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    FU Shuixing; ZHANG Shoulin; LI Chunxia; FENG Jianzhong; FANG Tonghui; SUN Baosheng

    2004-01-01

    Based on specific well-exposed rocks useful for high-quality remote sensing interpretation in the goldprospecting area in the eastern Tianshan, this paper gives a detailed description of a remote sensing model for metallogenic prediction. The model reveals that multi-spectral remote sensing data are integrated with high-resolution remote sensing data, and enhanced extraction and visual description of weak remote sensing information are used for prospecting. This model has tested in the given gold deposit, and used successfully in Au-Cu prospecting in the Kalatage area.

  4. Resource and Geological Characteristics of Gold Deposits in India%印度共和国金矿资源及其地质特征

    Institute of Scientific and Technical Information of China (English)

    成功; 邱献引; 孙卫宾; 李尚林; 罗彦军

    2015-01-01

    India’s gold mine has four basic types:greenstone belt type,conglomerate-type,alluvial gold mine and associated gold mine.India’s gold mine has a feature of wide distribution,relative concentration,less large and rich mineral deposits,and the great depth and so on.Greenstone type gold mine which is the most important gold type in India,concentrates Precambrian greenstone belt in South India craton and central India craton.Kolar gold mine and Hutii gold mine in the East of Darwar craton in south India are typical greenstone type gold mines. Kolar gold mine is a super-giant gold deposit with an average gold grade of 16 g/t,and gold reserves > 1 000 t;Hutti gold mine is a large gold deposit with an average grade of 4.85 g/t,and gold reserves >150 t.The proved reserves of India’s gold mine is very limited,but a lot of smaller gold deposits are widely distributed in India craton greenstone belts,which indicates there is a very good potential of gold resource.Increasing the investment in the exploration and development of India’s gold mine will make more gold resources with great value be discovered and may also completely change the status quo of India gold.%印度金矿类型主要有4种:绿岩型、砾岩型、砂金及伴生金矿,具有分布广、相对集中、规模小、品位低及埋深较大等特点。绿岩型金矿是印度最重要的金矿类型,集中分布在南印度克拉通和印度中央克拉通的前寒武系绿岩带中。南部东塔尔瓦尔克拉通的科拉尔金矿和胡蒂金矿是典型的绿岩型金矿,其中,科拉尔金矿金平均品位为16 g/t,黄金储量>1000 t,属于超大型金矿床;胡蒂金矿金平均品位为4.85 g/t,黄金储量>150 t,属于大型金矿床。印度金矿探明储量十分有限,但大量较小规模金矿广泛分布在印度克拉通绿岩带,预示印度金矿具有很好的资源潜力。增加印度金矿勘探和开发投入,将发现更多具有重要价值的金

  5. Application of U-Th-Pb phosphate geochronology to young orogenic gold deposits: New age constraints on the formation of the Grass Valley gold district, Sierra Foothills province, California

    Science.gov (United States)

    Taylor, Ryan D.; Goldfarb, Richard J.; Monecke, Thomas; Fletcher, Ian R.; Cosca, Michael A.; Kelly, Nigel M.

    2015-01-01

    The Grass Valley orogenic gold district in the Sierra Nevada foothills province, central California, the largest historic gold producer of the North American Cordillera, comprises both steeply dipping east-west (E-W) veins located along lithologic contacts in accreted ca. 300 and 200 Ma oceanic rocks and shallowly dipping north-south (N-S) veins hosted by the Grass Valley granodiorite; the latter have yielded about 70 percent of the 13 million ounces of historic lode gold production in the district. The oceanic host rocks were accreted to the western margin of North America between 200 and 170 Ma, metamorphosed to greenschist and amphibolite facies, and uplifted between 175 and 160 Ma. Large-scale magmatism in the Sierra Nevada occurred between 170-140 Ma and 120-80 Ma, with the Grass Valley granodiorite being emplaced during the older episode of magmatism. Uranium-lead isotopic dating of hydrothermal xenotime yielded the first absolute age of 162±5 Ma for the economically more significant N-S veins. The vein-hosted xenotime, as well as associated monazite, are unequivocally of hydrothermal origin as indicated by textural and chemical characteristics, including grain shape, lack of truncated growth banding, lack of a Eu anomaly, and low U and Th concentrations. Furthermore, the crack-seal texture of the veins, with abundant wallrock slivers, suggests their formation as a result of episodic fluid flow possibly related to reoccurring seismic events, rather than a period of fluid exsolution from an evolving magma. The N-S veins are temporally distinct from a younger 153-151 Ma gold event that was previously reported for the E-W veins. Overlapping U-Pb zircon (159.9±2.2 Ma) and 40Ar/39Ar biotite and hornblende (159.7±0.6 to 161.9±1.4 Ma) ages and geothermobarometric calculations indicate that the Grass Valley granodiorite was emplaced at ca. 160 Ma at elevated temperatures (~800°C) within approximately 3 km of the paleosurface and rapidly cooled to the ambient

  6. U-Pb SHRIMP Dating of Zircon from Quartz Veins of the Yangshan Gold Deposit in Gansu Province and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    QI Jinzhong; YUAN Shisong; LIU Zhijie; LIU Dunyi; WANG Yanbin; LI Zhihong; GUO Junhua; SUN Bin3

    2004-01-01

    The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±l.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.

  7. Theoretical prediction of gold vein location in deposits originated by a wall magma intrusion

    Science.gov (United States)

    Martin, Pablo; Maass-Artigas, Fernando; Cortés-Vega, Luis

    2016-05-01

    The isotherm time-evolution resulting from the intrusion of a hot dike in a cold rock is analized considering the general case of nonvertical walls. This is applied to the theoretical prediction of the gold veins location due to isothermal evolution. As in previous treatments earth surface effects are considered and the gold veins are determined by the envelope of the isotherms. The locations of the gold veins in the Callao mines of Venezuela are now well predicted. The new treatment is now more elaborated and complex that in the case of vertical walls, performed in previous papers, but it is more adequated to the real cases as the one in El Callao, where the wall is not vertical.

  8. SERS Taper-Fiber Nanoprobe Modified by Gold Nanoparticles Wrapped with Ultrathin Alumina Film by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Wenjie Xu

    2017-02-01

    Full Text Available A taper-fiber SERS nanoprobe modified by gold nanoparticles (Au-NPs with ultrathin alumina layers was fabricated and its ability to perform remote Raman detection was demonstrated. The taper-fiber nanoprobe (TFNP with a nanoscale tip size under 80 nm was made by heated pulling combined with the chemical etching method. The Au-NPs were deposited on the TFNP surface with the electrostatic self-assembly technology, and then the TFNP was wrapped with ultrathin alumina layers by the atomic layer deposition (ALD technique. The results told us that with the increasing thickness of the alumina film, the Raman signals decreased. With approximately 1 nm alumina film, the remote detection limit for R6G aqueous solution reached 10−6 mol/L.

  9. Electrical conduction processes in as-deposited indium phthalocyanine chloride thin films using gold and aluminium electrode combination

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Mammen; Menon, C S; Unnikrishnan, N V [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686 560, Kerala (India)

    2006-01-11

    Sandwich structures of the type (Au-InPcCl-Al) have been fabricated by successive vacuum deposition of indium phthalocyanine chloride (InPcCl) thin films and aluminium (Al) fingers onto Ohmic gold (Au) electrodes on glass substrates. Device characteristics of as-deposited Au/InPcCl/Al are obtained and found to show rectification properties. Current density-voltage characteristics under forward bias (aluminium electrode negative) are found to be due to Ohmic conduction at lower voltages. At higher voltages there is space charge limited conductivity (SCLC) controlled by an exponential trapping distribution above the valence edge. Transport properties of the material at ambient temperature have been obtained from the analysis of the samples in the Ohmic and SCLC regions. Under the reverse bias, Schottky emission is identified at lower voltages.

  10. Gold-Coated Nanoelectrospray Emitters Fabricated by Gravity-Assisted Etching Self-Termination and Electroless Deposition.

    Science.gov (United States)

    Zhu, Xudong; Liang, Yu; Weng, Yejing; Chen, Yuanbo; Jiang, Hao; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2016-12-06

    To improve the stability and sensitivity of nanoelectrospray for liquid chromatography-mass spectroscopy (LC-MS) analysis, we present a new method to fabricate gold-coated emitters. Via gravity-assisted etching self-termination, the emitter with a tapered outer surface and a straight inner surface is prepared with good reproducibility, without the need of fluid introduced to protect internal surface during etching. Followed by electroless deposition, the emitter is further coated with gold film homogeneously, by which the relative standard deviation (RSD) value of total ion current in 160 h is <5%, showing good stability. Compared to that obtained by a commercial emitter, the identified protein number from 2 μg HeLa cell digests is increased over 10%, contributed by the stable electrospray and improved signal intensity of peptides. Furthermore, the integrated gold-coated emitter is prepared at the end of the ultranarrow-bore packed column (inner diameter of 25 μm), and 218 proteins are identified from 2 ng HeLa cell digests. All of these results demonstrate the great promise of such emitters for use in ultrasensitive proteome analysis.

  11. Decomposition of NO in gas phase by gold nanoparticles supported on titanium dioxide synthesized by the deposition-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Fernandez, J., E-mail: javier.fernandez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados, Av. Miguel de Cervantes 120, Complejo Industrial C.P. 31109, Chihuahua, Chih. (Mexico); Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Eje Central Lazaro Cardenas 152, C.P. 07730, D.F. (Mexico); Zanella, R. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, UNAM, Circuito exterior S/N, Ciudad Universitaria, C.P. 04510, A.P. 70-186, Delegacion Coyoacan, D.F. (Mexico); Aguilar-Elguezabal, A. [Centro de Investigacion en Materiales Avanzados, Av. Miguel de Cervantes 120, Complejo Industrial C.P. 31109, Chihuahua, Chih. (Mexico); Arizabalo, R.D.; Castillo, S.; Moran-Pineda, M. [Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Eje Central Lazaro Cardenas 152, C.P. 07730, D.F. (Mexico)

    2010-10-25

    In the present work, the synthesis, characterization and photoactivity concerning the nitrogen monoxide (NO) decomposition of sol-gel Au/TiO{sub 2} photocatalysts are reported. TiO{sub 2} was prepared by gelling titanium (IV) isopropoxide, and gold nanoparticles were added by the deposition-precipitation method with urea. The catalysts with different gold concentrations were characterized by the following techniques: BET, XRD, UV-vis and dark-field TEM. It was found that by using this synthesis method, a high dispersion of gold nanoparticles on TiO{sub 2} was reached (4.4-6.7 nm), and the obtained structure lead to a band gap energy that is lower than the one observed for undoped TiO{sub 2}. A NO + O{sub 2} mixture (150 ppm) was used to evaluate the photocatalytic activity in situ, at room temperature, under atmospheric pressure and a UV lamp was used as radiation source. The photocatalytic conversion of nitrogen monoxide (NO) was followed by FTIR, which reached 96% in 60 min. The Au/TiO{sub 2} materials showed an enhanced photocatalytic activity when compared with the reference TiO{sub 2}.

  12. A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits, southwestern Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)

    NIE Aiguo; MEI Shiquan; GUAN Daiyun; WU Pan; ZHANG Zhuru

    2008-01-01

    A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province. The Longtan Formation contains abundant basalt, tuff and siliceous rocks. All rocks of the Longtan Formation are enriched in gold, which were deposited in a limited platform environment in the transition zone from marine to continental. The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west, which led to the formation of a peculiar gold-bearing formation with coal series strata. This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province. In response to the remobilization of the Emei mantle plume during the Yanshanian period, As, Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams, thereafter forming ore-forming hydrothermal solutions.When these elements were transported in the coal seams, large amounts of As, Au and other elements were enriched in pyrite within the coal seams, thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.

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

    Science.gov (United States)

    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

  14. Geology,Geochemistry and Genesis of the Mazhuangshan Gold Deposit in Hami,East Tianshan,Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    陈世忠; 周济元; 等

    2001-01-01

    The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc,where there are distributed intermediate-acid magmatic rocks emplaced during the Middle-Late Carboniferous.There are more than 20 orebodies in the area with an average gold grade 6.4×10-6 at present.The dominant metallic minerals are natural gold,auriferous silver,natural silver,pyrite and galena.Pyrite is the key gold carrier,high in Fe and low in S.Wall-rock alteraions mainly include pyritization,silicification,and sericitization.Carbonation alteration wasextensive at the late stage,often resulting in a high-grade orebody.Three mineralization stages may be distinguished. The peak homogenization temperatures of primary fluid inclusions rage from 240 to 260℃.Mineralization pressures and depths are 47.2-68.8MPa and 1.6-2.3km respec tively,showing the ore-forming features of hypergene gold deposit.Te average salinity is 15wt% NaCl equivalent.Fluid inclusion geochemistry data show that Ca2+ is for higher than Mg2+,and mK/mNa+,mNa2+/mCa2+(0.001-0.338),m∑Cl/m∑S and m∑C/m∑S ratios change with the reduction parameter [R=(CO=CH4)/CO2]and temperature.And the gold contents of ores and gangues are positively correlated with R. The pH values of inclusion water in quartz range from 5.850 7.4.Oxygen fugacity(fO2) ranges from 10-55Pa to 10-47Pa,sulfur fugacity(fS2)is about 10-13,and Eh values are estimated to be about-0.6eV.Theδ34 S values of the fluid were determined to be +3.94‰to+4.98‰.206Pb/204Pb and 207Pb/208Pb ratios in pyrite are 18.269-18.352,15.550-15.633and 38.077-38.355,respectively,The ∑REE values(4.7×10-6-43.1×10-6) of ores and gangues are obviously lower than those of the host magmatic rocks,but their REE and trace element spider diagrams are similar to those of the host magmatic rocks,suggesting that the water consists dominantly of meteoric water,mixed with a part of magmatic water.The metallogenic element mostly came from magmatites.The deposit is closely related to

  15. Helium and argon isotopic compositions of the Longquanzhan gold deposit in the Yishu fault zone and their geological implications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Longquanzhan gold deposit hosted in granitic cataclasites with mylontization of the foot wall of the main Yishui-Tangtou fault. 3He/4He ratios in fluid inclusions range from 0.14 to 0.24 R/Ra,close to those of the crust-source helium. 40Ar/36Ar ratios were measured to be 289-1811, slightly higher than those of atmospheric argon. The results of analysis of helium and argon isotopes suggested that ore-forming fluids were derived chiefly from the crust. The δ18O values of fluid inclusions from vein quartz range from -1.78‰ to 4.07‰, and the δD values of the fluid inclusions vary between -74‰ and -77‰. The hydrogen and oxygen isotope data indicated that the ore-forming fluid for the Longquanzhan gold deposit had mixed with meteoric water in the process of mineralization. This is consistent with the conclusion from the helium and argon isotope data.

  16. In situ surface-enhanced Raman spectroscopic study of formic acid electrooxidation on spontaneously deposited platinum on gold.

    Science.gov (United States)

    Muralidharan, Ranjani; McIntosh, Michael; Li, Xiao

    2013-06-28

    Present formic acid fuel cell efficiency is limited by low kinetics at the anode, indicating the need for effective catalysts to improve the formic acid oxidation. As a prerequisite, the nature of adsorbed species and specifically the reaction intermediates formed in this process needs to be examined. This work focuses on the electrooxidation of formic acid and the nature of the intermediates at a platinum-modified gold surface prepared through spontaneous deposition using a combination of electrochemistry and in situ surface enhanced Raman spectroscopy (SERS). This Pt-modified gold electrode surface assists in oxidizing formic acid at potentials as low as 0.0 V vs. Ag/AgCl which is 0.15 V more negative than a bare Pt surface. The oxidation current obtained on the Pt-modified gold electrode is 72 times higher than on a bare Au surface and 5 times higher than on a bare Pt surface at the same potential. In situ SERS has revealed the involvement of formate at a low frequency as the primary intermediate in this electrooxidation process. While previous studies mainly focused on the formate mode at ca. 1322 cm(-1), it is the first time that a formate peak at ca. 300 cm(-1) was observed on a Pt or Pt-associated surface. A unique relationship has been observed between the formic acid oxidation currents and the SERS intensity of this formate adsorbate. Furthermore, the characteristic Stark effect of the formate proves the strong interaction between the adsorbate and the catalyst. Both electrochemical and spectroscopic results suggest that the formic acid electrooxidation takes place by the dehydrogenation pathway involving a low frequency formate intermediate on the Pt-modified gold electrode catalyst.

  17. A metamorphic mineral source for tungsten in the turbidite-hosted orogenic gold deposits of the Otago Schist, New Zealand

    Science.gov (United States)

    Cave, Ben J.; Pitcairn, Iain K.; Craw, Dave; Large, Ross R.; Thompson, Jay M.; Johnson, Sean C.

    2016-09-01

    The orogenic gold deposits of the Otago Schist, New Zealand, are enriched in a variety of trace elements including Au, As, Ag, Hg, W and Sb. We combine laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) traverses and images to show that detrital rutile is the most important host mineral for W in the subgreenschist facies rocks. Furthermore, the prograde metamorphic recrystallisation of detrital rutile to titanite releases significant amounts of W (potentially 0.41 g/tonne of rock). Scheelite development closely follows the progression of this W-liberating reaction. Scheelite micrograins form early within the fabric of the rock evolving to locally and regionally sourced scheelite-bearing veins. Scheelite from syn-metamorphic veins at Fiddlers Flat and Lake Hāwea shows distinct differences in composition compared with scheelite from late-metamorphic veins at the Macraes Mine, the latter of which is enriched in REEs, Y and Sr. We suggest that the scheelite at Macraes became enriched due to the liberation of these elements during alteration of the Ca-silicate minerals epidote and titanite by the ore-forming fluid. These results are supportive of recent models for orogenic gold mineralisation in the Otago Schist, whereby prograde metamorphic recrystallisation of diagenetic or detrital metal-rich mineral phases (pyrite to pyrrhotite: Au, As, Ag, Hg and Sb; rutile to titanite: W) releases significant amounts of metals into the concurrently developing metamorphic fluids that can be subsequently focussed into regional structures and form significant tungsten-bearing orogenic gold deposits.

  18. Relantionships between gold mineralization and granite - Discussion with the support of a pluridisciplinary study of the Passa Tres gold deposit (South Brazil)

    Science.gov (United States)

    Dressel, Bárbara; Chauvet, Alain; Trzaskos, Barbara; Biondi, Joao Carlos; Bruguier, Olivier; Monie, Patrick; Villanova, Sandro; Bazille, Jose

    2016-04-01

    represent the early stage of vein formation. These observations favor the link between late-magmatic fluids and veins formation. In order to constrain this assumption, a campaign of absolute dating has been undertaken. Zircons from granite and aplite for the magmatic feature and adularia, muscovite, sericite and molybdenite grains for the hydrothermal ones were selected and will be dated by, respectively U-Pb, Ar-Ar and Re-Os methods. Preliminary field results may suggest that gold-quartz veins may formed during the magmatic-hydrothermal transition and that mineralizing fluids possibly represent the late stages of magmatic fluid. Their mode of formation looks to be consistent with an extensional setting. With the help of all these new data, a discussion will be initiated about the genetic model of granite-hosted gold deposits and particularly on this specific case represented by the Passa Três deposit in which huge quartz veins, and no stockwork, are only formed inside the granite and not in surrounding rocks.

  19. A chemiluminescent metalloimmunoassay based on silver deposition on colloidal gold labels.

    Science.gov (United States)

    Li, Zheng-Ping; Liu, Cheng-Hui; Fan, Yong-Shan; Wang, Yu-Cong; Duan, Xin-Rui

    2006-12-15

    A sensitive chemiluminescent (CL) immunoassay of human immunoglobulin (IgG) which combined the inherent high sensitivity of CL analysis with the dramatic signal amplification of silver precipitation on colloidal gold tags was developed. First, the sandwich-type complex was formed in this protocol by the primary antibody immobilized on the polystyrene wells, the analyte in the sample, and the secondary antibody labeled with colloidal gold. Second, the colloidal gold was treated by an Ag(+) reduction solution, which resulted in the catalytic precipitation of silver on the surface of colloidal gold. Third, a large number of Ag(+) were oxidatively released in HNO(3) solution from the silver metal anchored on the sandwich-type complexes and then the human IgG was indirectly determined by a sensitive combined CL reaction of Ag(+)-K(2)S(2)O(8)-Mn(2+)- H(3)PO(4)-luminol. The chemiluminescence intensity depends linearly on the logarithm of the concentration of human IgG over the range of 0.02-50ngml(-1) and detection limit (3sigma) is 0.005ngml(-1) (i.e., approximately 3x10(-14)M, 3amol in 100-mul sample). This assay has been successfully applied to the determination of human IgG in human serum samples and showed great potential for numerous applications in immunoassay.

  20. Geochemical Characteristics of Two Types of Ores from Jinshan Shear Zone—hosted Gold Deposit,Jiangxi,with a Discussion on the Mechanism of Two—stage Mineralization

    Institute of Scientific and Technical Information of China (English)

    季峻峰; 刘英俊; 等

    1995-01-01

    Two types of gold ores,siliceous mylonite and quartz vein,formed at the first and second stages of mineralization respectively, can be clearly recognized in the shear zone-hosted gold deposit at Jinshan, Jiangxi.Similarity in REE and trace elements between the siliceous mylonite and the country rocks indicates that the ore metals were supplied by the surrounding strata during the first stage of mineralization.On the other hand, as indicated by fluid inclusion data,the ore-forming fluid at the second stage was of meteoric origin and the precipitation of gold was caused by phase separation.

  1. Source of ore-forming material for the Huangtuliang gold deposit, Hebei Province and ore prospecting in the deep periphery

    Institute of Scientific and Technical Information of China (English)

    NIU Shuyin; SUN Aiqun; WANG Baode; HAN Yuchou; WEI Minghui; ZHANG Hai; ZHANG Ge; SHI Ping; WANG Wenxing

    2008-01-01

    The Huangtuliang gold deposit is characterized by its wide and large ore belt, stable extension and closely spaced orebodies. Unfortunately, no orebody was found by deep drilling. As a result, ore prospecting in this region was once put into dilemma. Detailed analysis of ore-forming and ore-controlling structures in the mining district by the authors has revealed that the ore-forming and ore-controlling structure in this mining district is a steeply dipping (85°-110°/∠70°-85° N-NNE), spade-shaped ductile shear zone, and the ore-controlling structures are a series of nearly erected second-ordered faults which are developed in the upper part of the ductile shear zone, intersecting with the ductile shear zone. Deep cutting of the ductile shear zone made it possible the ascending of ore fluids from the mantle plume at depth and these ore fluids would migrate upwards along the ductile shear zone under certain temperature and pressure conditions. Along their ascending path, the ore fluids would extract ore-forming elements from the country rocks and the extracted ore-forming elements would be deposited as ores in the hanging-wall second-ordered faults. The reason why no orebody was found in early prospecting at depth is that northward-dipping drilling in the southern part of the shear zone extended so deeply as to be beneath the shear zone. Only shallow-level orebodies could be found by southward-dipping drilling practice in the northern part of the shear zone.The location where deep-seated orebodies occurred shifted northwards and the orebodies occurred at greater depth.Therefore, it is natural that no orebody could be found when drill core passed through the shear zone. After the ore-forming and ore-controlling structures were well understood, the focus of ore prospecting was placed on the deep-level, northward-penetrating veins. In this way a number of new blind orebodies of great thickness have been found. On the basis of research development in the mining

  2. Gold mineralisation and orogenic metamorphism in the Lena province of Siberia as assessed from Chertovo Koryto and Sukhoi Log deposits

    Directory of Open Access Journals (Sweden)

    Marina A. Yudovskaya

    2016-05-01

    Full Text Available The Chertovo Koryto gold deposit (80 t Au at 1.84 g/t in the Lena world-class province, Siberia, is hosted in a metamorphosed sequence of the Paleoproterozoic Mikhailovsk Formation that comprises the oldest black shale strata of the Baikal-Patom region. The mineralisation is confined to the thrust zone complicated with a conjugate anticline fold, zones of shearing and dislocation. The structural position of the mineralisation is similar to that at the giant Sukhoi Log deposit in the neighbouring Mama-Bodaibo zone. In the latter, the isotope age data suggest that Khomolkho black shales, hosts to Sukhoi Log mineralisation, are of Ediacaran age and underwent prograde metamorphism during early Paleozoic. The geochemical composition of the terrigenous rocks that host Sukhoi Log, Chertovo Koryto, and a number of other deposits at the various stratigraphic levels throughout the Proterozoic sequence have much in common. They do not show elevated metal contents above the common black shale abundances, except for Au and As, which is at variance with the accepted view on diagenetic enrichment of black shales in the Lena province. The occurrence of sagenitic rutile in quartz and chlorite pseudomorphs after biotite and other petrographic observations provide evidence on a retrograde nature of the metamorphic mineral assemblages in the Mikhailovsk rocks. The sulphides are pyrrhotite and arsenopyrite with very minor pyrite at Chertovo Koryto, whereas pyrite is the predominant sulphide in the Sukhoi Log ore. Fluid inclusion data on both deposits emphasise a high-temperature nature of the mineralisation albeit revealing great contrast in the fluid composition. Sukhoi Log mineralisation was formed at mixing between low-salinity aqueous solutions and dense gaseous carbonic fluids, which facilitated effective gold scavenging and precipitation, as demonstrated by thermodynamic simulation. The precursory devolatilisation of the Mikhailovsk sediments at the prograde

  3. Gold mineralisation and orogenic metamorphism in the Lena province of Siberia as assessed from Chertovo Koryto and Sukhoi Log deposits

    Institute of Scientific and Technical Information of China (English)

    Marina A. Yudovskaya; Vadim V. Distler; Vsevolod Yu. Prokofiev; Nickolay N. Akinfiev

    2016-01-01

    The Chertovo Koryto gold deposit (80 t Au at 1.84 g/t) in the Lena world-class province, Siberia, is hosted in a metamorphosed sequence of the Paleoproterozoic Mikhailovsk Formation that comprises the oldest black shale strata of the Baikal-Patom region. The mineralisation is confined to the thrust zone complicated with a conjugate anticline fold, zones of shearing and dislocation. The structural position of the mineralisation is similar to that at the giant Sukhoi Log deposit in the neighbouring Mama-Bodaibo zone. In the latter, the isotope age data suggest that Khomolkho black shales, hosts to Sukhoi Log mineralisation, are of Ediacaran age and underwent prograde metamorphism during early Paleozoic. The geochemical composition of the terrigenous rocks that host Sukhoi Log, Chertovo Koryto, and a number of other deposits at the various stratigraphic levels throughout the Proterozoic sequence have much in common. They do not show elevated metal contents above the common black shale abundances, except for Au and As, which is at variance with the accepted view on diagenetic enrichment of black shales in the Lena province. The occurrence of sagenitic rutile in quartz and chlorite pseudomorphs after biotite and other petrographic observations provide evidence on a retrograde nature of the metamorphic mineral assemblages in the Mikhailovsk rocks. The sulphides are pyrrhotite and arsenopyrite with very minor pyrite at Chertovo Koryto, whereas pyrite is the predominant sulphide in the Sukhoi Log ore. Fluid inclusion data on both deposits emphasise a high-temperature nature of the mineralisation albeit revealing great contrast in the fluid composition. Sukhoi Log mineralisation was formed at mixing be-tween low-salinity aqueous solutions and dense gaseous carbonic fluids, which facilitated effective gold scavenging and precipitation, as demonstrated by thermodynamic simulation. The precursory devola-tilisation of the Mikhailovsk sediments at the prograde stage results in

  4. Electroless Deposited Gold Nanoparticles on Glass Plates as Sensors for Measuring the Dielectric Constant of Solutions

    OpenAIRE

    Kobayashi, Y.; Ishii, Y.

    2013-01-01

    This work describes a method for the deposition of Au nanoparticles on glass plates (Au-glass). An electroless metal plating technique was extended to the Au nanoparticle deposition. The technique consisted of three steps that took place on the glass plate: (1) adsorption of Sn2+ ions, (2) deposition of metallic Ag nuclei generated by reducing Ag+ ions with Sn2+ ions on the Sn-adsorbed sites, and (3) deposition of Au nanoparticles by reducing Au+ ions on the Ag surface. TEM observation reveal...

  5. Formation of a paleothermal anomaly and disseminated gold deposits associated with the Bingham Canyon porphyry Cu-Au-Mo system, Utah

    Science.gov (United States)

    Cunningham, C.G.; Austin, G.W.; Naeser, C.W.; Rye, R.O.; Ballantyne, G.H.; Stamm, R.G.; Barker, C.E.

    2004-01-01

    The thermal history of the Oquirrh Mountains, Utah, indicates that hydrothermal fluids associated with emplacement of the 37 Ma Bingham Canyon porphyry Cu-Au-Mo deposit extended at least 10 km north of the Bingham pit. An associated paleothermal anomaly enclosed the Barneys Canyon and Melco disseminated gold deposits and several smaller gold deposits between them. Previous studies have shown the Barneys Canyon deposit is near the outer limit of an irregular distal Au-As geochemical halo, about 3 km beyond an intermediate Pb-Zn halo, and 7 km beyond a proximal pyrite halo centered on the Bingham porphyry copper deposit. The Melco deposit also lies near the outer limit of the Au-As halo. Analysis of several geothermometers from samples collected tip to 22 km north of the Bingham Canyon porphyry Cu-Au-Mo deposit indicate that most sedimentary rocks of the Oquirrh Mountains, including those at the gold deposits, have not been regionally heated beyond the "oil window" (less than about 150??C). For geologically reasonable heating durations, the maximum sustained temperature at Melco, 6 km north of the Bingham pit, and at Barneys Canyon, 7.5 km north of the pit, was between 100??C and 140??C, as indicated by combinations of conodont color alteration indices of 1.5 to 2, mean random solid bitumen reflectance of about 1.0 percent, lack of annealing of zircon fission tracks, and partial to complete annealing of apatite fission tracks. The pattern of reset apatite fission-track ages indicates that the gold deposits are located approximately on the 120??C isotherm of the 37 Ma paleothermal anomaly assuming a heating duration of about 106 years. The conodont data further constrain the duration of heating to between 5 ?? 104 and 106 years at approximately 120??C. The ??18O of quartzite host rocks generally increases from about 12.6 per mil at the porphyry to about 15.8 per mil approximately 11 km from the Bingham deposit. This change reflects interaction of interstitial clays in

  6. Orogenic-type copper-gold-arsenic-(bismuth) mineralization at Flatschach (Eastern Alps), Austria

    Science.gov (United States)

    Raith, Johann G.; Leitner, Thomas; Paar, Werner H.

    2015-10-01

    high Hg content (up to 11 mass %). The Cu-Au deposits in the Flatschach area show similarities with meso- to epizonal orogenic lode gold deposits regarding the geological setting, the structural control of mineralization, the type of alteration, the early (stage 1) sulfide assemblage and composition of gold. Unique about the Flatschach district is the lower-temperature overprint of copper arsenides (domeykite and koutekite) and copper sulfides (djurleite, yarrowite/spionkopite) on earlier formed sulfide mineralization. Based on mineralogical considerations temperature of stage 2 mineralization was between about 70 °C and 160 °C. Gold was locally mobilized during this low-temperature hydrothermal overprint as well as during stage 3 supergene oxidation and cementation processes.

  7. A Study on the Geological—Geochemical Dynamics of Hydrothermal Ore Deposition as Exemplified by the Muping—Rushan Gold Deposit Belt,Eastern Shandong,China

    Institute of Scientific and Technical Information of China (English)

    赵伦山; 高太忠; 等

    1996-01-01

    This paper presents a method of establishing a hydrothermal ore-forming reaction system.On the basis of the study of four typical hydrothermal deposits,the following conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been sions concerning geochemical dynaamic controlling during hydrothermal mineralization have been drawn:(1)The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system.(2)During hydrothermal mineralization the activites of ore-bearing faults can be divideb into two stages:the brittle splitting stage and the brittle-tough tensing stage,which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system.(3)The hydrothermal ore-forming reaaction system is an open dynamic system.At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids.And at the brittle-tough tensing stage,the ore-forming system was in a weak supersaturated state;with decreasing temperature and pressure the crystallization of oreforming material would show down,and it can be regarded as an equilibrated state.(4)In the lates stages of hydrothermal evolution,gold would be concentrated in the residual ore-forming solution.The pulsating fracture activite in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution,forming high-grage“fissure”gold ore.This ore-forming process could be called the coupling mechanism of ore formation.

  8. Physico-Chemical Modeling of the Sulfo-Arsenide System of Gold Bearing Ore Deposits

    Directory of Open Access Journals (Sweden)

    N. V. VILOR

    2010-12-01

    Full Text Available The existence of gold-arsenic mineralization, the presence of enhanced concentrations of gold in arsenopyrite, especially in its fine grain varieties showing positive gold-arsenic ratios in gold-quartz and gold-pyritic ores indicate the important role of As in hydrothermal gold transport. The most accessible approach to the investigation of these complicated systems is provided by physico-chemical modeling. In the present work the isobaric isothermal potentials (DG°f 298 of thioarsenides, the most important group of arsenic compounds in the solution, have been determined and refined on the basis of the creation of physico-chemical models using the data on the As sulfide solubility in the As – S – O – H system. The data obtained were reconciled with the thermodynamic data available by solving the reverse thermodynamic problem. Numerical physico-chemical modeling has been carried out for a series of tests in both pure water and hydrogen sulfide solutions (0.0032 - 0.011m with the initial pH values from 1.14 to 8.4 in the 25-250°C temperature range under saturated water steam pressure. The computer-calculated constants are included in the modeling of tests on orpiment dissolution in sulfide-sodium solutions. The As2S3ryst solubility in the 25-250°C temperature range has first been obtained. A specific feature of the process is a sharp increase in dissolved arsenic total concentration as the pH value of the hydrothermal phase rises from 4 to 6-7. Concentration increases and gradient decreases with temperature rise. The predominant forms are represented by thioarsenites. Just as in acidic, so in weakly and moderately alkaline solutions the orpiment solubility is caused by the concentration combination of thioarsenous acid H3AsS3 and its oligomers H4As2S50 and H2As2S40. At a temperature of over 200-250°C these concentrations can be compared only with that of the AsOH (HS2o complex of mixed composition.

  9. Recent U.S. Geological Survey Studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada-Results of a 5-Year Project

    Science.gov (United States)

    Gough, Larry P.; Day, Warren C.

    2010-01-01

    This report presents summary papers of work conducted between 2002 and 2007 under a 5-year project effort funded by the U.S. Geological Survey Mineral Resources Program, formerly entitled 'Tintina Metallogenic Province: Integrated Studies on Geologic Framework, Mineral Resources, and Environmental Signatures.' As the project progressed, the informal title changed from 'Tintina Metallogenic Province' project to 'Tintina Gold Province' project, the latter being more closely aligned with the terminology used by the mineral industry. As Goldfarb and others explain in the first chapter of this report, the Tintina Gold Province is a convenient term used by the mineral exploration community for a 'region of very varied geology, gold deposit types, and resource potential'. The Tintina Gold Province encompasses roughly 150,000 square kilometers, bounded by the Kaltag-Tintina fault system on the north and the Farewell-Denali fault system on the south. It extends westward in a broad arc, some 200 km wide, from northernmost British Columbia, through the Yukon, through southeastern and central Alaska, to southwestern Alaska. The climate is subarctic and, in Alaska, includes major physiographic delineations and ecoregions such as the Yukon-Tanana Upland, Tanana-Kuskokwim Lowlands, Yukon River Lowlands, and the Kuskokwim Mountains. Although the Tintina Gold Province is historically important for some of the very first placer and lode gold discoveries in northern North America, it has recently seen resurgence in mineral exploration, development, and mining activity. This resurgence is due to both new discoveries (for example, Pogo and Donlin Creek) and to the application of modern extraction methods to previously known, but economically restrictive, low-grade, bulk-tonnage gold resources (for example, Fort Knox, Clear Creek, and Scheelite Dome). In addition, the Tintina Gold Province hosts numerous other mineral deposit types, possessing both high and low sulfide content, which

  10. Facile room temperature deposition of gold nanoparticle-ionic liquid hybrid film on silica substrate

    Science.gov (United States)

    Krishnamurthy, S.; Reddy, D. Harikishore Kumar; Sankar, G.; Yun, Yeoung-Sang

    2017-01-01

    This work presents facile synthesis of gold nanoparticle (Au NP)-ionic liquid hybrid film of synthesis, and even coating on Si (111) substrate. XRD, XPS, and XAS spectral data confirm the presence of Au(0) while EXAFS data indicated the presence of small particles or incomplete surface species. Cross-sectional analysis using FE-SEM and edge length measurement using AFM showed that the film thickness is ca 10 nm.

  11. Characteristics of ore-controlling structure in Maevatanana gold deposit,Madagascar%马达加斯加 Maevatanana 金矿床构造控矿特征

    Institute of Scientific and Technical Information of China (English)

    杨喜安; 刘善宝; 王光良; 黄凡; 李鹏; 王成辉; 陈毓川

    2013-01-01

    Madagascar sits in eastern Africa ,ranking the fourth largest island in the world .To this day ,there is no organised or industrialized gold exploitation in Maevatanana region besides manual mining work .This is a large amount considering that all is presently from artisanal mining of mainly alluvial deposits .The region's estimated gold produc-tion is 3-4 tonnes/year.The Au deposit in the Maevatanana region is a classical quartz vein type gold deposit in the greenstone belt by the results of chemical test of drill cores ,the quartz veins was controlled by faults .The chemical tes-ting of the drill core demonstrates that the gold deposits in the Madagascar mainly comprise gold-bearing quartz veins , subordinating the gold-bearing felsic veins .The late gold-bearing quartz veins crosscut the gold-bearing felsic veins , suggesting that there is two epochs of mineralization in the study area .The gold-bearing felsic veins are hosted by the NNW-trending shear zone ,and the gold-bearing quartz veins is related to the intersection of the NNW-trending shear zone and the NNE-striking faults .The NNE-striking faults reworked and crosscut the gold-bearing quartz veins .%马达加斯加位于非洲东部,是世界第四大岛。到目前为止,马达加斯加Maevatanana 地区还没有进行工业化开采金矿床,主要靠手工开采,估计马达加斯加每年的金产量3~4t左右。根据钻孔岩芯化验结果可知,本地区的矿化类型主要为含金石英脉,其次为含金长英质脉。后期的含金石英脉切穿了早期的含金长英质脉,说明该地区具有2期成矿作用。含金长英质脉容矿构造为NNW向剪切带,含金石英脉产在NNW向剪切带和NNE向断层交汇处。 NNE向断层后期活动,破坏了含金石英脉。

  12. ASSESSMENT OF THE CHEMICAL POLLUTION OF THE SOIL, GROUND AND BOTTOM SEDIMENTS AT KLEN GOLD AND SILVER DEPOSIT

    Directory of Open Access Journals (Sweden)

    Bryukhan' Fedor Fedorovich

    2012-10-01

    Full Text Available Currently, prospecting and design-related works are performed prior to the upcoming launch of mining operations at Klen gold and silver deposit in Chukot Autonomous District. The anthropogenic impact of the geological exploration in this intact territory has been produced since 1984. A considerable amount of borehole drilling, prospecting, road building, and temporary housing development has been performed. The engineering research, including ecological surveys, has been completed to assess the ecological impact of upcoming exploratory and mining operations at the deposit. Assessment of the geochemical condition of the landscape constituents, including the soil, ground and bottom sediments is of special importance in terms of their engineering protection and rational management of the natural environment. The above assessments were based on the field sampling made by «Sibgeoconsulting», CJSC (Krasnoyarsk and the laboratory research made by accredited laboratories of Federal State Unitary Geological Enterprise «Urangeolograzvedka» (Irkutsk and «Krasnoyarskgeologiya» (Krasnoyarsk. The analysis of the chemical pollution of soils, ground and bottom sediments is based on the examination of 30 samples. Peculiarities of the chemical composition of samples extracted at the deposit were identified. It has been discovered that pH values of the soil vary from 5.1 to 7.3. The concentration of metal in bottom sediments exceeds its concentration in the soil by far. Almost all irregular features of the sample water in the whole territory of the deposit are caused by the anthropogenic impact. In general, the metal content in soils, ground and bottom sediments within the territory of the deposit is slightly different from the regular clarke.

  13. Z-scan studies of the nonlinear optical properties of gold nanoparticles prepared by electron beam deposition.

    Science.gov (United States)

    Mezher, M H; Nady, A; Penny, R; Chong, W Y; Zakaria, R

    2015-11-20

    This paper details the fabrication process for placing single-layer gold (Au) nanoparticles on a planar substrate, and investigation of the resulting optical properties that can be exploited for nonlinear optics applications. Preparation of Au nanoparticles on the substrate involved electron beam deposition and subsequent thermal dewetting. The obtained thin films of Au had a variation in thicknesses related to the controllable deposition time during the electron beam deposition process. These samples were then subjected to thermal annealing at 600°C to produce a randomly distributed layer of Au nanoparticles. Observation from field-effect scanning electron microscope (FESEM) images indicated the size of Au nanoparticles ranges from ∼13 to ∼48  nm. Details of the optical properties related to peak absorption of localized surface plasmon resonance (LSPR) of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear effects on the fabricated Au nanoparticle layers where it strongly relates LSPR and nonlinear optical properties.

  14. Formation conditions of high-grade gold-silver ore of epithermal Tikhoe deposit, Russian Northeast

    Science.gov (United States)

    Volkov, A. V.; Kolova, E. E.; Savva, N. E.; Sidorov, A. A.; Prokof'ev, V. Yu.; Ali, A. A.

    2016-09-01

    The Tikhoe epithermal deposit is located in the Okhotsk-Chukotka volcanic belt (OChVB) 250 km northeast of Magadan. Like other deposits belonging to the Ivan'insky volcanic-plutonic depression (VTD), the Tikhoe deposit is characterized by high-grade Au-Ag ore with an average Au grade of 23.13 gpt Au and Au/Ag ratio varying from 1: 1 to 1: 10. The detailed explored Tikhoe-1 orebody is accompanied by a thick (20 m) aureole of argillic alteration. Pyrite is predominant among ore minerals; galena, arsenopyrite, sphalerite, Ag sulfosalts, fahlore, electrum, and küstelite are less abundant. The ore is characterized by abundant Sebearing minerals. Cu-As geochemical specialization is noted for silver minerals. Elevated Se and Fe molar fractions of the main ore minerals are caused by their formation in the near-surface argillic alteration zone. The veins and veinlets of the Tikhoe-1 ore zone formed stepwise at a temperature of 230 to 105°C from Nachloride solution enriched in Mg and Ca cations with increasing salinity. The parameters of the ore-forming fluid correspond to those of epithermal low-sulfidation deposits and assume the formation of high-grade ore under a screening unit of volcanic rocks. In general, the composition of the ore-forming fluid fits the mineralogy and geochemistry of ore at this deposit. The similarity of the ore composition and parameters of the ore-forming fluid between the Tikhoe and Julietta deposits is noteworthy. Meanwhile, differences are mainly related to the lower temperature and fluid salinity at the Julietta deposit with respect to the Tikhoe deposit. The fluid at the Julietta deposit is depleted in most components compared with that at the Tikhoe deposit except for Sb, Cd, and Ag. The results testify to a different erosion level at the deposits as derivatives of the same ore-forming system. The large scale of the latter allows us to predict the discovery of new high-grade objects, including hidden mineralization, which is not exposed at

  15. Isotopic indication to source of ore materials and fluids of the Wangfeng gold deposit in Tianshan: A case study of metallogenesis during collisional orogenesis

    Institute of Scientific and Technical Information of China (English)

    陈华勇; 鲍景新; 张增杰; 刘玉琳; 倪培; 凌洪飞

    2000-01-01

    The Wangfeng gold deposit is one of the five most important gold deposits in the Tian-shan. Studies of its metallogenic time, space, geodynamic background, ore feature and ore fluid have proved that the deposit formed in the late Paleozoic continental collision, and consequently is a suitable delegate to probe mineralizing regularities during collisiona! orogenesis. Isotopic studies including O, D, C, S, Pb and Sr reveal ore materials derived from sedimentary association (including carbonate and sulfate), which further refers to the Hercynian carbonate-silicolite-argillite formation north to Wangfeng camp. At the end of Paleozoic, the southward intracontinental subduction of Hercynian synthem along the Hongwuyueqiao fault down to the Central Tianshan terrane induced large-scale fluidization which extracted and out-transported ore materials from Hercynian synthem upto shallow fair positions, and finally resulted in the formation of the Wangfeng deposit. This study excludes the possibility of other tecton

  16. Characteristics and origin of ore-forming fluids of Jinchangqing gold (copper) ore deposit (s) in Xiangyun, Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    HE Mingqin; SONG Huanbin; LIU Jiajun; LI Chaoyang

    2005-01-01

    On the basis of results of the studies of primary fluid inclusions, and the hydrogen and oxygen isotope data, the authors concluded that the early-stage ore-forming fluid from the Jinchangqing gold (copper) ore deposit is a kind of sulfate type hot brine characterized by medium temperature and salinity, genetically related to the late-stage ore-forming fluid derived from an acidic and more reductive environment. However, the late-stage ore-forming fluid is a sort of low temperature and low salinity chloride-type hot brine which originated from a lower pressure, acidic and more oxidative environment. In general, the ore fluids were derived from the late-stage, or largely from the early-stage groundwater-derived meteoric water, which has a 12‰-17‰ heavier oxygen isotopic composition than the original rain water (δ 18 O= -15.3‰ ), and were formed during gold mineralization as a product of oxygen isotope exchange during the reaction between ore-forming fluid and wall rocks under a lower water/rock ratio condition.

  17. Gold nanoparticles deposited capillaries for in-capillary microextraction capillary zone electrophoresis of monohydroxy-polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Wang, Huiyong; Knobel, Gaston; Wilson, Walter B; Calimag-Williams, Korina; Campiglia, Andres D

    2011-03-01

    This article presents the first application of gold nanoparticles deposited capillaries as pre-concentration devices for in-capillary microextraction CZE and their use for the analysis of monohydroxy-polycyclic aromatic hydrocarbons in synthetic urine samples. The successful separation of 1-hydroxypyrene, 9-hydroxyphenanthrene, 3-hydroxybenzo[a]pyrene (3-OHbap), 4-hydroxybenzo[a]pyrene and 5-hydroxybenzo[a]pyrene under a single set of electrophoretic conditions is demonstrated as well as the feasibility to obtain competitive ultraviolet absorption LOD with commercial instrumentation. Enrichment factors ranging from 87 (9-OHphe) to 100 (3-OHbap) made it possible to obtain LOD ranging from 9 ng/mL (9-OHphe and 3-OHbap) to 14 ng/mL (4-hydroxybenzo[a]pyrene).

  18. Humidity sensing using vertically oriented arrays of ReS2 nanosheets deposited on an interdigitated gold electrode

    Science.gov (United States)

    Yang, Aijun; Gao, Jian; Li, Baichang; Tan, Jiawei; Xiang, Yu; Gupta, Tushar; Li, Lu; Suresh, Shravan; Idrobo, Juan Carlos; Lu, Toh-Ming; Rong, Mingzhe; Koratkar, Nikhil

    2016-12-01

    We report a novel humidity sensor featuring vertically oriented arrays of ReS2 nanosheets grown on an interdigitated gold electrode by chemical vapor deposition. The vertical orientation of the nanosheets is important since it maximizes the exposed surface area for water adsorption/desorption. We find that the resistance of the ReS2 film decreases sensitively with increasing relative humidity, which we attribute to charge transfer from the absorbed H2O molecules to the n-doped ReS2 nanosheets. In addition to high sensitivity, the ReS2 sensors exhibit fast response/recovery time and excellent reversibility with minimal hysteresis. Moreover, our fabrication approach involving the direct (1-step) growth of the ReS2 films on an interdigitated electrode (without any transfer using wet chemistry or lithography) greatly simplifies the device architecture and has important practical benefits for the low-cost and scalable deployment of such sensor devices.

  19. REDBED RELATED GOLD DEPOSIT,LUBINSIEROSZOWICE COPPER DISTRICT,SW POLAND

    Institute of Scientific and Technical Information of China (English)

    A.Piestrzynski; J.Pieczonka

    2001-01-01

    @@ Underground prospecting within the Lubin-Sieroszowice mining area which took place during last 5 years,led to a discovery of a new type of Au,Pt and Pd mineralisation located0-0.5 m below the copper-silver orebody in the south-western part of the Polish Permian Basin.The gold-bearing zone lies mainly in the Weissliegendes sandstone (Iower Permian),but locally transgresses the stratigraphic sequence into the overlying kupferschiefer and Werra limestone (Zechstein).

  20. REDBED RELATED GOLD DEPOSIT,LUBINSIEROSZOWICE COPPER DISTRICT,SW POLAND

    Institute of Scientific and Technical Information of China (English)

    A.Piestrzynski; J.Pieczonka

    2001-01-01

    Underground prospecting within the Lubin-Sieroszowice mining area which took place during last 5 years,led to a discovery of a new type of Au,Pt and Pd mineralisation located0-0.5 m below the copper-silver orebody in the south-western part of the Polish Permian Basin.The gold-bearing zone lies mainly in the Weissliegendes sandstone (Iower Permian),but locally transgresses the stratigraphic sequence into the overlying kupferschiefer and Werra limestone (Zechstein).……

  1. Distributing Characteristics of Heavy Metal Elements in A Tributary of Zhedong River in Laowangzhai Gold Deposit, Yunnan (China): An Implication to Environmentology from Sediments

    Science.gov (United States)

    Yang, Shuran; Danĕk, Tomáš; Yang, Xiaofeng; Cheng, Xianfeng

    2016-10-01

    Five heavy metal contents from five sediments and seven sediment profiles in an upstream reach of Zhedong river in Laowangzhai gold deposit were investigated in this research, along with analysis of the horizontal distribution, the surface distribution, the vertical distribution and the interlayer distribution of five heavy metal contents: arsenic (As), mercury (Hg), copper (Cu), lead (Pb) and zinc (Zn). The potential ecological risk of five heavy metals was evaluated to help understanding pollution control of Laowangzhai deposit.

  2. Zircon U-Pb dating and geochemical study of the Xianggou granite in the Ma’anqiao gold deposit and its relationship with gold mineralization

    Institute of Scientific and Technical Information of China (English)

    LEE; Ben

    2010-01-01

    Single zircon LA-ICP-MS U-Pb dating and lithogeochemical studies have been performed on the Xianggou monzonitic granitic porphyry outcropped in the Ma’anqiao gold deposit.A weighted average U-Pb age of 242.0±0.8 Ma for Xianggou monzonitic porphyry has been obtained.This corresponds with the conclusions of previous studies indicating a syn-orogenic age (242±21 Ma) of the Qinling Orogenic Belt,suggesting that the formation of the Xianggou granite should be associated with the collisional event of the North China Plate and the Yangtze Plate in the Indosinian period.The Xianggou granite is characterized by the high silicon and alkali of high K calc-alkaline series granites.It is rich in Al (Al2O3=14.49%-15.61%) and Sr (457.10-630.82 ppm),poor in Y (<16 ppm) and HREE (Yb<0.45 ppm),and exhibits high ratios of Sr/Y (76.24-97.34) and (La/Yb)N (29.65-46.10),as well as strongly fractionated REE patterns.These geochemical characteristics suggest the Xianggou granite can be classified as C-type adakitic rock.The initial Sr isotope ratios for the Xianggou granite vary from 0.70642 to 0.70668,εNd(t) values from -4.54 to -3.98,and TDM values from 1152 Ma to 1220 Ma.The low εNd(t) and ISr and high TDM values,as well as Na2O/K2O ratios of the Xianggou granite are close to 1 (Na2O/K2O=0.95-1.10),indicating that it is not an I-type adakite formed by partial melting of the subducting oceanic crust,nor adakitic rock formed by melting of the underplated basaltic lower crust,but the product of partial melting of the nonunderplated basaltic thickened lower crust.Zircons from the Xianggou pluton have a homogeneous Hf isotopic composition with negative εHf(t) values (between -9.7 and -5.9,with an average of -6.9),indicating that the rock-forming materials were mostly extracted from the ancient crust,not from the depleted mantle.The Xianggou monzonitic granitic porphyry is rich in LILE and LREE and depleted in HSFE,HREE and Y;the composition of trace element and REE are similar to

  3. Ore features and gold occurrence in Yinwagou Gold Deposit,Gansu Province%甘肃阴洼沟金矿床矿石特征及金的赋存状态研究

    Institute of Scientific and Technical Information of China (English)

    赵民; 郭月琴; 赵国斌; 温志亮; 杨鹏飞; 李普涛; 吴天娇

    2016-01-01

    Characteristics of gold minerals and the occurrence of gold have been determined in Yinwagou Gold Deposit ,on the basis of systematic laboratory study ,such as electron microscope observation ,multi-element analysis ,e-lectronic microprobe energy spectrum analysis , electronic microprobe wavelength spectrum analysis , mineral phase a-nalysis .The result shows the gold ores mainly have three different mineralogical types ,that is low sulphide altered rock type gold ore,low sulphide cataclastic quartz-vein type gold ore and low sulphide ankerite -albite-quartz-vein type gold ore ,and Au is the only one industrially valuable element;the metallic mineral content in the ore is low and they are mainly limonite ,hematite and pyrite;non-metallic minerals are mainly quartz ,followed by sericite ,carbonate min-erals,feldspar,chlorite and kaolinite; gold minerals are native gold,and the average fineness of native gold is 975;The main type of dissemination is fissure gold ,followed by inclusion gold ,few in the form of the intergranular gold;grain size of native gold is dominated by fine visible gold ,followed by microgranular gold .Native gold is primarily visi-ble gold,followed by microscopic gold .%为了查清阴洼沟金矿床矿石特征及金的赋存状态,采用电子显微镜、多元素分析、电子探针能谱分析、电子探针波谱分析、物相分析等技术方法,对阴洼沟金矿床的金矿石、金矿物进行了系统的研究.研究结果表明:金矿石工艺类型主要有少硫化物蚀变岩型金矿石、少硫化物碎裂石英脉型金矿石和少硫化物铁白云石-钠长石-石英脉型3种,且有工业价值的元素只有Au;矿石中金属矿物含量较低,主要是褐铁矿、赤铁矿及黄铁矿,非金属矿物主要是石英,其次是绢云母、碳酸盐矿物、长石、绿泥石及高岭石;金矿物为自然金,金成色平均为975;金的嵌布类型以裂隙金为主,其次为包裹金,粒间金含量较少;自然金以细

  4. GENERAL CHARACTER OF MULTISTAGES OF METALLOGENESIS FOR MICRO-MESOTHERMAL GOLD DEPOSITS:EXAMPLES FROM ZHANG-BALING TECTONIC BELT,ANHUI,CHINA

    Institute of Scientific and Technical Information of China (English)

    DAI Ta-gen; HUANG De-zhi; QIU Rui-long; XU Xiang

    2001-01-01

    In Zhangbaling Tectonic Belt,two types of mineralization,auriferous quartz veins and alteration halos,can observed within many deposits.The pressure of metallogenesis of auriferous alteration halos is much higher than that of quartz vein,the temperatures of metallogeneses of these two types of orebodies are don't the same Geochemistry study indicates that both of them are micro-mesothermal deposits related to Yanshanian granites.The results of proton microprobe analysis of sulphides from the gold deposits in the area show that the "invisible" gold existed in sulphides is in the form of micro inclusions,and the concentration of "invisible" gold in sulphide minerals within quartz vein is poorer than that from alteration halos.Field observation shows that the structural modality of the fractures controlling the orebodies of auriferous quartz vein is different from that of the auriferous alteration zones.The fracture controlling the orebodies of auriferous alteration halos is compress-shear fracture,auriferous quartz vein is controlled by extensive fault.The alteration halos crosscut by auriferous quartz vein.The wallrocks of the former altered strongly and developed alteration zones well.The wallrocks of auriferous quartz vein altered slightly.The results of tectonogeochemical study shows that the concentration of associated metallogenesis elements and intensity of alteration are positively correlated with tectonic deformation strength for auriferous alteration halos.It indicates that it is probably a general character for micro-mesothermal gold deposits due to the multistages of metallogeneses took place.The tectonic environment is the most important fact determining the mechanism of fluid flow and precipitation of gold,and then the types of mineralization and modes of gold.

  5. Oxygen Reduction Reaction on Pt Overlayers Deposited onto a Gold Film: Ligand, Strain, and Ensemble Effect

    DEFF Research Database (Denmark)

    Deng, Yu-Jia; Tripkovic, Vladimir; Rossmeisl, Jan;

    2016-01-01

    We study the oxygen reduction reaction (ORR), the catalytic process occurring at the cathode in fuel cells, on Pt layers prepared by electrodeposition onto an Au substrate. Using a nominal Pt layer by layer deposition method previously proposed, imperfect layers of Pt on Au are obtained. The ORR ...

  6. The Chahnaly low sulfidation epithermal gold deposit, western Makran volcanic arc, southeastern Iran

    Science.gov (United States)

    Sholeh, Ali; Rastad, Ebrahim; Huston, David L.; Gemmell, J. Bruce; Taylor, Ryan D.

    2016-01-01

    The Chahnaly low-sulfidation epithermal Au deposit and nearby Au prospects are located northwest of the intermittently active Bazman stratovolcano on the western end of the Makran volcanic arc, which formed as the result of subduction of the remnant Neo-Tethyan oceanic crust beneath the Lut block. The arc hosts the Siah Jangal epithermal and Kharestan porphyry prospects, near Taftan volcano, as well as the Saindak Cu-Au porphyry deposit and world-class Reko Diq Cu-Au porphyry deposit, near Koh-i-Sultan volcano to the east-northeast in Pakistan. The host rocks for the Chahnaly deposit include early Miocene andesite and andesitic volcaniclastic rocks that are intruded by younger dacitic domes. Unaltered late Miocene dacitic ignimbrites overlie these rocks. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb zircon geochronology data yield ages between 21.8 and 9.9 Ma for the acidic-intermediate regional volcanism. The most recent volcanic activity of the Bazman stratovolcano involved extrusion of an olivine basalt during Pliocene to Quaternary times. Interpretation of geochemical data indicate that the volcanic rocks are synsubduction and calc-alkaline to subalkaline. The lack of a significant negative Eu anomaly, a listric-shaped rare earth element pattern, and moderate La/Yb ratios of host suites indicate a high water content of the source magma.

  7. Electroless Deposited Gold Nanoparticles on Glass Plates as Sensors for Measuring the Dielectric Constant of Solutions

    Directory of Open Access Journals (Sweden)

    Y. Kobayashi

    2013-01-01

    Full Text Available This work describes a method for the deposition of Au nanoparticles on glass plates (Au-glass. An electroless metal plating technique was extended to the Au nanoparticle deposition. The technique consisted of three steps that took place on the glass plate: (1 adsorption of Sn2+ ions, (2 deposition of metallic Ag nuclei generated by reducing Ag+ ions with Sn2+ ions on the Sn-adsorbed sites, and (3 deposition of Au nanoparticles by reducing Au+ ions on the Ag surface. TEM observation revealed that metallic Au nanoparticles with a size of  nm were formed on the glass surface. A surface plasmon resonance absorption peak was observed, and its peak wavelength redshifted by immersing the Au-glass into a solution with a large dielectric constant. The redshift corresponded qualitatively to the calculation by the Mie theory accompanying the Drude expression, which was based on the change of the dielectric constant of the solution. The obtained results indicated that the Au-glass functioned as a sensor for measuring the dielectric constant of the solution.

  8. Size effects under a strong magnetic field: transverse magnetoresistance of thin gold films deposited on mica

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, Raul C [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago (Chile); HenrIquez, Ricardo [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); GarcIa, Juan Pablo [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago (Chile); Moncada, Ana MarIa [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); Espinosa, Andres [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago (Chile); Robles, Marcelo [Departamento de Ciencias de la Construccion, Universidad Tecnologica Metropolitana, Dieciocho 390, Santiago (Chile); Kremer, German [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); Moraga, Luis [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); Cancino, Simon [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); Morales, Jose Roberto [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago (Chile); RamIrez, Adan [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago (Chile); Oyarzun, Simon; Suarez, Marco Antonio; Chen, David [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago (Chile); Zumelzu, Ernesto; Lizama, Claudio [Facultad de Ciencias de la IngenierIa, Universidad Austral, General Lagos 2086, Valdivia (Chile)

    2006-04-05

    We report measurements of transverse magnetoresistance where the signal can be attributed to electron-surface scattering, together with measurements of the surface roughness of the films on an atomic scale. The measurements were performed with a scanning tunnelling microscope (STM) on four thin gold films evaporated onto mica. The magnetoresistance exhibits a marked thickness dependence: at 4 K and 9 T is about 5% for the thinner (69 nm) film, and about 14% for the thicker (185 nm) film. Sondheimer's theory provides an accurate description of the temperature dependence of the resistivity, but predicts a magnetoresistance one order of magnitude smaller than that observed at 4 K. Calecki's theory in the limit of small roughness correlation length, predicts a resistivity two orders of magnitude larger than observed at 4 K.

  9. Combining multiple correspondence analysis with factorial kriging analysis for geochemical mapping of the gold-silver deposit at Marrancos (Portugal)

    Energy Technology Data Exchange (ETDEWEB)

    Reis, A.P.; Sousa, A.J.; Ferreira da Silva, E.; Patinha, C.; Fonseca, E.C

    2004-04-01

    This study concerns the application of multiple correspondence analysis and factorial kriging analysis to soil data, and aims to identify spatial patterns and superficial soil anomalies of the Au and Ag deposit at Marrancos, Vila Verde. The mineral deposit can be described as a quartz auriferous shear-zone, consisting of a quartz breccia of tectonic origin hosted by metamorphic rocks (hornfels). Gold is associated with arsenopyrite and pyrite, and Ag with galena and galenobismuthite. A total of 286 soil samples were analysed for Fe, Cu, Zn, Pb, Co, Ni, Mn, Ag and Bi by atomic absorption spectrometry, As, Se, Te and Sb by atomic absorption spectrometry-hydride generation system and Au by inductively coupled plasma-atomic emission spectroscopy after extraction of the metal by an organic solvent (methyl-isobutylketone). The methodology used included (a) multiple correspondence analysis applied to soil data to obtain some factors that summarize geochemical information, (b) a structural analysis (variography) in order to account for spatial variability of these factors, and (c) factorial kriging analysis used to split these factors into their spatial components. This methodology allowed an efficient multi-element characterization of the spatial patterns as well as the identification and interpretation of significant anomalies, not always associated to Au-bearing geological structures.

  10. Underpotential deposition of tin(II) on a gold disc electrode and determination of tin in a tin plate sample.

    Science.gov (United States)

    Qiao, Zhiqing; Shang, Wei; Zhang, Xin; Wang, Chunming

    2005-04-01

    This work describes a study of the underpotential deposition (UPD) of Sn2+ on a polycrystalline gold disc electrode using cyclic voltammetry (CV) and chronocoulometry (CC). Sn2+ ions showed well-defined peaks from UPD and UPD stripping (UPD-S) in 1 mol/L HCl solutions, while bulk deposition (BD) and BD stripping (BD-S) of the ions were also observed. The measured UPD shifts, DeltaE(UPD), between the UPD-S and the BD-S peaks were more than 200 mV. The UPD charge and the surface coverage of tin were measured by CC. A new method for determining Sn2+ was therefore developed, based on the excellent electrochemical properties of the Au/Sn UPD system. A plot of the UPD-DPASV (differential pulse anodic stripping voltammetry) signal versus the Sn(II) concentration was obtained for [Sn(II)] of 1.98x10(-7) to 3.64x10(-5) M. The method developed here has been applied to determine the tin in a tin plate sample.

  11. Gold deposition on pyrite and the common sulfide minerals: An STM/STS and SR-XPS study of surface reactions and Au nanoparticles

    Science.gov (United States)

    Mikhlin, Yuri L.; Romanchenko, Alexander S.

    2007-12-01

    Gold species spontaneously deposited on pyrite and chalcopyrite, pyrrhotite, galena, sphalerite from HAuCl 4 solutions at room temperature, as well as the state of the reacted mineral surfaces have been characterized using synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS), scanning tunneling microscopy and tunneling spectroscopy (STM/STS). The deposition of silver from 10 -4 M AgNO 3 has been examined for comparison. Gold precipitates as metallic nanoparticles (NPs) from about 3 nm to 30 nm in diameter, which tends to aggregate forming larger particles, especially on pyrite. The Au 4f binding energies increase up to 1 eV with decreasing size of individual Au 0 NPs, probably due to the temporal charging in the final state. Concurrently, a positive correlation between the tunneling current and the particle size was found in STS. Both these size effects were observed for unusually large, up to 20 nm Au particles. In contrast, silver deposited on the minerals as nanoparticles of semiconducting sulfide showed no shifts of photoelectron lines and different tunneling spectra. The quantity of gold deposited on pyrite and other minerals increased with time; it was lower for fracture surfaces and it grew if minerals were moderately pre-oxidized, while the preliminary leaching in Fe(III)-bearing media inhibited the following Au deposition. After the contact of polished minerals with 10 -4 M AuCl4- solution (pH 1.5) for 10 min, the gold uptake changed in the order CuFeS 2 > ZnS > PbS > FeAsS > FeS 2 > Fe 7S 8. It was noticed that the open circuit (mixed) potentials of the minerals varied in approximately the same order, excepting chalcopyrite. We concluded that the potentials of minerals were largely determined by Fe(II)/Fe(III) couple, whereas the reduction of gold complexes had a minor effect. As a result, the deposition of gold, although it proceeded via the electrochemical mechanism, increased with decreasing potential. This suggests, in particular, that the

  12. Low Energy Electron Diffraction (LEED)-Auger-Thin-Layer Electrochemical Studies of the Underpotential Deposition of Lead onto Gold Single Crystals.

    Science.gov (United States)

    1979-12-15

    Underpotential Deposition of Lead onto Gold Single Crystals by P. ilagans, A. Homa, W. O’Grady and E. Yeager Prepared as part of the Ph.D. thesis of P. L. Hagans...from Repot) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on revorso ide If necessary and Identify by block numb-) Underpotential deposition , lead...If necepaury an IdantHy by block number) ’The underpotential deposition of lead onto very clean and well-ordered single crystal Au samples was

  13. Determination of low levels of cadmium ions by the under potential deposition on a self-assembled monolayer on gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Noyhouzer, Tomer [Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Mandler, Daniel, E-mail: mandler@vms.huji.ac.il [Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2011-01-17

    The electrochemical determination of low levels of Cd using a self-assembled monolayer (SAM) modified Au electrode is reported. Determination was based on the stripping of Cd, which was deposited by under potential deposition (UPD). A series of short alkanethiol SAMs bearing different end groups, i.e., sulfonate, carboxylate and ammonium, were examined. Lowest level of detection (ca. 50 ng L{sup -1}) was achieved with a 3-mercaptopropionic acid (MPA) monolayer using subtractive anodic square wave voltammetry (SASV). Additional surface methods, namely, reductive desorption and X-ray photoelectron spectroscopy, were applied to determine the interfacial structure of the electrodeposited Cd on the modified electrodes. We conclude that the deposited Cd forms a monoatomic layer, which bridges between the gold surface and the alkanethiol monolayer associating with both the gold and the sulfur atoms.

  14. Photoinduced cathodic deposition of CdTe nanoparticles on polycrystalline gold substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Sunyoung; Paeng, Ki-Jung [Department of Chemistry, Yonsei University, Wonju Campus, Wonju, Kangwondo 220-710 (Korea); Choi, Byunghyun; Myung, Noseung [Department of Applied Chemistry, Konkuk University Chungju Campus, Chungju, Chungbuk 380-701 (Korea); Rajeshwar, Krishnan [Center for Renewable Energy Science and Technology (CREST), The University of Texas at Arlington, Arlington, TX 76109-0065 (United States)

    2007-06-15

    A combination of photocathodic stripping and precipitation was used to prepare CdTe nanoparticles (size range: 30-60 nm) that were immobilized on a polycrystalline Au substrate. Thus visible light irradiation of a Te modified Au surface generated Te{sup 2-} species in situ followed by interfacial reaction with added Cd{sup 2+} ions in 0.1 M Na{sub 2}SO{sub 4} electrolyte. The resultant CdTe compound semiconductor deposited as nanosized particles uniformly dispersed on the Au substrate surface. This approach to CdTe nanoparticle deposition was monitored by a combination of electrochemical methods (voltammetry, chronoamperometry) and quartz crystal microgravimetry in the 'dark' and under illumination. The synthesized CdTe nanoparticles were characterized by scanning electron microscopy and energy dispersive X-ray analyses and laser Raman spectroscopy. (author)

  15. Molecular rectification with identical metal electrodes at low temperatures Thin film deposition; Gold; Molecular electronics; Langmuir- Blodgett; Au/LB/Au structures; Fabrication

    CERN Document Server

    Okazaki, N

    2003-01-01

    A gold deposition technique for the fabrication of Au/LB/Au structures has been developed. The kinetic energy of evaporated gold atoms is reduced by scattering the gold atoms from argon gas. Moreover, the samples are cooled down below 173K (-100 deg C) to avoid the diffusion of gold atoms into the LB films and to fabricate electrically continuous thin gold electrodes (This technique has since been used in fabrication of Au/LB/Au structures even with monolayer LB films (Metzger, et al. (2001)). To measure the current-voltage characteristics of the Au/LB/Au structures at liquid helium temperatures, new junction geometries have been explored. To avoid the direct contact of the Gallium-Indium eutectic onto the LB films, which is the cause of the breakdown of the junction at lower temperatures, a cross electrode junction geometry is used. The problem of poor Langmuir-Blodgett film deposition at the penumbra region of the base electrode is avoided by covering the penumbra region with an insulating omega-tricosenoic...

  16. Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

    Science.gov (United States)

    Gorji, Mohammad Saleh; Razak, Khairunisak Abdul; Cheong, Kuan Yew

    2013-10-15

    Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.

  17. Age constraints on the hydrothermal history of the Prominent Hill iron oxide copper-gold deposit, South Australia

    Science.gov (United States)

    Bowden, Bryan; Fraser, Geoff; Davidson, Garry J.; Meffre, Sebastien; Skirrow, Roger; Bull, Stuart; Thompson, Jay

    2016-12-01

    The Mesoproterozoic Prominent Hill iron-oxide copper-gold deposit lies on the fault-bound southern edge of the Mt Woods Domain, Gawler Craton, South Australia. Chalcocite-bornite-chalcopyrite ores occur in a hematitic breccia complex that has similarities to the Olympic Dam deposit, but were emplaced in a shallow water clastic-carbonate package overlying a thick andesite-dacite pile. The sequence has been overturned against the major, steep, east-west, Hangingwall Fault, beyond which lies the clastic to potentially evaporitic Blue Duck Metasediments. Immediately north of the deposit, these metasediments have been intruded by dacite porphyry and granitoid and metasomatised to form magnetite-calc-silicate skarn ± pyrite-chalcopyrite. The hematitic breccia complex is strongly sericitised and silicified, has a large sericite ± chlorite halo, and was intruded by dykes during and after sericitisation. This paper evaluates the age of sericite formation in the mineralised breccias and provides constraints on the timing of granitoid intrusion and skarn formation in the terrain adjoining the mineralisation. The breccia complex contains fragments of granitoid and porphyry that are found here to be part of the Gawler Range Volcanics/Hiltaba Suite magmatic event at 1600-1570 Ma. This indicates that some breccia formation post-dated granitoid intrusion. Monazite and apatite in Fe-P-REE-albite metasomatised granitoid, paragenetically linked with magnetite skarn formation north of the Hangingwall Fault, grew soon after granitoid intrusion, although the apatite experienced U-Pb-LREE loss during later fluid-mineral interaction; this accounts for its calculated age of 1544 ± 39 Ma. To the south of the fault, within the breccia, 40Ar-39Ar ages yield a minimum age of sericitisation (+Cu+Fe+REE) of dykes and volcanics of ˜1575 Ma, firmly placing Prominent Hill ore formation as part of the Gawler Range Volcanics/Hiltaba Suite magmatic event within the Olympic Cu-Au province of the

  18. Age constraints on the hydrothermal history of the Prominent Hill iron oxide copper-gold deposit, South Australia

    Science.gov (United States)

    Bowden, Bryan; Fraser, Geoff; Davidson, Garry J.; Meffre, Sebastien; Skirrow, Roger; Bull, Stuart; Thompson, Jay

    2017-08-01

    The Mesoproterozoic Prominent Hill iron-oxide copper-gold deposit lies on the fault-bound southern edge of the Mt Woods Domain, Gawler Craton, South Australia. Chalcocite-bornite-chalcopyrite ores occur in a hematitic breccia complex that has similarities to the Olympic Dam deposit, but were emplaced in a shallow water clastic-carbonate package overlying a thick andesite-dacite pile. The sequence has been overturned against the major, steep, east-west, Hangingwall Fault, beyond which lies the clastic to potentially evaporitic Blue Duck Metasediments. Immediately north of the deposit, these metasediments have been intruded by dacite porphyry and granitoid and metasomatised to form magnetite-calc-silicate skarn ± pyrite-chalcopyrite. The hematitic breccia complex is strongly sericitised and silicified, has a large sericite ± chlorite halo, and was intruded by dykes during and after sericitisation. This paper evaluates the age of sericite formation in the mineralised breccias and provides constraints on the timing of granitoid intrusion and skarn formation in the terrain adjoining the mineralisation. The breccia complex contains fragments of granitoid and porphyry that are found here to be part of the Gawler Range Volcanics/Hiltaba Suite magmatic event at 1600-1570 Ma. This indicates that some breccia formation post-dated granitoid intrusion. Monazite and apatite in Fe-P-REE-albite metasomatised granitoid, paragenetically linked with magnetite skarn formation north of the Hangingwall Fault, grew soon after granitoid intrusion, although the apatite experienced U-Pb-LREE loss during later fluid-mineral interaction; this accounts for its calculated age of 1544 ± 39 Ma. To the south of the fault, within the breccia, 40Ar-39Ar ages yield a minimum age of sericitisation (+Cu+Fe+REE) of dykes and volcanics of ˜1575 Ma, firmly placing Prominent Hill ore formation as part of the Gawler Range Volcanics/Hiltaba Suite magmatic event within the Olympic Cu-Au province of the

  19. Dating Magmatic Hornblende and Biotite and Hydrothermal Sericite by Laser Probe Technique:Constraints on Genesis of Wangershan Gold Deposit, Eastern Shandong Province,China

    Institute of Scientific and Technical Information of China (English)

    Li Jianwei; Vasconcelos P M; Zhou M F; Duzgoren-Aydin N S

    2003-01-01

    The Wangershan gold deposit and spatially related Shangzhuang granite, eastern Shandong Province, have been precisely dated by 40 Ar/39 Ar laser incremental heating technique. Magmatic hornblende and biotite, collected from the Shangzhuang granites, yielded well-defined and reproducible plateau ages at 128. 1-127.5 and 124.4-124. 1 Ma (2σ), measuring the cooling ages of the intrusion at ca. 500 ℃ and 300-350 ℃, respectively. Hydrothermal sericite extracted from auriferous vein gave high-quality plateau ages between (120. 6±0.3) Ma and (120. 0±0. 4) Ma (2σ). Given the similarity of the closure temperature for argon diffusion (300-350 ℃ ) in the sericite mineral to the homogenization temperature of primary fluid inclusions in the quartz from gold ores, and the intergrowth of sericite with native gold, present 40Ar/39 Ar sericite ages can be reliably interpreted in terms of the mineralization age for the Wangershan deposit. 40 Ar/39 Ar hornblende and biotite ages permit an estimate for the cooling rate of the Shangzhuang granite at about 50 ℃/Ma. There are abundant intermediate-mafic dikes in most gold camps of eastern Shandong, whose ages of formation have been previously constrained mainly at 121-119 Ma. The temporal association between the Shangzhuang granite, the Wangershan gold deposit, and the widespread dikes confirms that intrusive activity, gold mineralization, and dike emplacement in this region were broadly coeval, reflecting significant continental lithosphere thinning and resulting crustal extension of Early Cretaceous in eastern China.

  20. Formation of Archean batholith-hosted gold veins at the Lac Herbin deposit, Val-d'Or district, Canada: Mineralogical and fluid inclusion constraints

    Science.gov (United States)

    Rezeau, Hervé; Moritz, Robert; Beaudoin, Georges

    2017-03-01

    The Lac Herbin deposit consists of a network of mineralized, parallel steep-reverse faults within the synvolcanic Bourlamaque granodiorite batholith at Val-d'Or in the Archean Abitibi greenstone belt. There are two related quartz-tourmaline-carbonate fault-fill vein sets in the faults, which consist of subvertical fault-fill veins associated with subhorizontal veins. The paragenetic sequence is characterized by a main vein filling ore stage including quartz, tourmaline, carbonate, and pyrite-hosted gold, chalcopyrite, tellurides, pyrrhotite, and cubanite inclusions. Most of the gold is located in fractures in deformed pyrite and quartz in equilibrium with chalcopyrite and carbonates, with local pyrrhotite, sphalerite, galena, cobaltite, pyrite, or tellurides. Petrography and microthermometry on quartz from the main vein filling ore stage reveal the presence of three unrelated fluid inclusion types: (1) gold-bearing aqueous-carbonic inclusions arranged in three-dimensional intragranular clusters in quartz crystals responsible for the main vein filling stage, (2) barren high-temperature, aqueous, moderately saline inclusions observed in healed fractures, postdating the aqueous-carbonic inclusions, and considered as a remobilizing agent of earlier precipitated gold in late fractures, and (3) barren low-temperature, aqueous, high saline inclusions in healed fractures, similar to the crustal brines reported throughout the Canadian Shield and considered to be unrelated to the gold mineralization. At the Lac Herbin deposit, the aqueous-carbonic inclusions are interpreted to have formed first and to represent the gold-bearing fluid, which were generated contemporaneous with regional greenschist facies metamorphism. In contrast, the high-temperature aqueous fluid dissolved gold from the main vein filling ore stage transported and reprecipitated it in late fractures during a subsequent local thermal event.

  1. A comparison of iron oxide-rich joint coatings and rock chips as geochemical sampling media in exploration for disseminated gold deposits

    Science.gov (United States)

    Crone, W.; Larson, L.T.; Carpenter, R.H.; Chao, T.T.; Sanzolone, R.F.

    1984-01-01

    We evaluated the effectiveness of iron oxide-rich fracture coatings as a geochemical sampling medium for disseminated gold deposits, as compared with conventional lithogeochemical methods, for samples from the Pinson mine and Preble prospect in southeastern Humboldt County, Nevada. That disseminated gold mineralization is associated with Hg, As, and Sb is clearly demonstrated in these deposits for both fracture coatings and rock chip samples. However, the relationship is more pronounced for fracture coatings. Fracture coatings at Pinson contain an average of 3.61, 5.13, 14.37, and 3.42 times more Au, As, Sb and Hg, respectively, than adjacent rock samples. At Preble, fracture coatings contain 3.13, 9.72, 9.18, and 1.85 times more Au, As, Sb and Hg, respectively, than do adjacent rock samples. Geochemical anomalies determined from fracture coatings are thus typically more intense than those determined from rock samples for these elements. The sizes of anomalies indicated by fracture coatings are also somewhat larger, but this is less obvious. In both areas, Sb anomalies are more extensive in fracture coatings. At Preble, some Hg and Au anomalies are also more extensive in fracture coatings. In addition to halos formed by the Hg, As and Sb, high values for Au/Ag and Zn/(Fe + Mn) are closely associated with gold mineralization at the Pinson mine. The large enhancement in geochemical response afforded by fracture coatings indicates a definite potential in the search for buried disseminated gold deposits. ?? 1984.

  2. Detection and mapping of hydrothermally altered rocks in the vicinity of the Comstock Lode, Virginia Range, Nevada, using enhanced Landsat images

    Science.gov (United States)

    Ashley, Roger P.; Goetz, A.F.H.; Rowan, L.C.; Abrams, M.J.

    1979-01-01

    The Virginia Range, immediately southeast of Reno, Nev., consists mainly of flows, breccias, and turfs of Miocene age. Most of these volcanic rocks are of intermediate composition; rhyodacite is the most common rock type. Basalt, rhyolite and rhyolite tuff, and tuffaceous sedimentary rocks of Miocene and Pliocene age also cover substantial areas in the range. Pre-Tertiary metasedimentary, metavolcanic, and granitic rocks are exposed in scattered inliers, mostly along the southern and eastern margins of the range. Several large areas and many small areas within the volcanic pile were subjected to hydrothermal alteration during and after the period of intermediate volcanic activity. Economic precious metal mineralization is spatially and temporally associated with the hydrothermal alteration in several areas. The most important deposit is the Comstock Lode, which produced 192 million troy ounces of silver and 8.3 million troy ounces of gold from epithermal veins (Bonham, 1969). The hydrothermally altered rocks include silicified, advanced argillic, montmorillonite-bearing argillic, and propylitic types. The first three types typically contain pyrite, and some propylitic rocks contain pyrite as well. Supergene oxidation of these pyritic rocks produces limonitic bleached rocks. The term 'limonite,' as used here, refers to any combination of the minerals hematite, goethite, and Jarosite. Where vegetation cover is sparse to moderate, these limonitic rocks are readily identified on Landsat images enhanced by the color-ratio composite technique developed by Rowan and others (1974), so the altered areas can be mapped. About 30 percent tree cover (here mainly pinyon pine) is sufficient to change the spectral signature of individual picture elements (pixels) enough so that limonitic materials can no longer be uniquely identified. As in all other areas where this technique has been applied, limonitic unaltered rocks with intermediate to high albedos have the same appearance on

  3. DISCOVERY OF GOLD ORE DEPOSITS IN CHINA AND THE IMPLICATIOINS%中国金矿床发现的启示

    Institute of Scientific and Technical Information of China (English)

    王建平; 戚开静; 杨立强

    2001-01-01

    Through gathering basic data of 258 gold ore deposits in China, the paper proposes that enough investment on gold exploration should be ensured. Also we should strengthen study on gold ore-forming theory and develop new technologies and new methods in order to enhance the effect of gold ore exploration. By this way, we can increase gold reserves to meet the demands of gold production.%通过对中国258个金矿床资料的统计,简析了中国金矿床在发现年代、规模、类型以及找矿关键因素等方面的一些规律,提出新时期中应保障黄金勘查工作的投入,加强金成矿理论研究,发展完善找金新技术、新方法,以提高金矿找矿的成效,不断增加地质储量,满足黄金生产的需要.

  4. In situ controlled sputtering deposition of gold nanoparticles on MnO2 nanorods as surface-enhanced Raman scattering substrates for molecular detection.

    Science.gov (United States)

    Jiang, Tao; Zhang, Li; Jin, Han; Wang, Xiaolong; Zhou, Jun

    2015-04-28

    Single-crystal tetragonal α-MnO2 nanorods with different amounts of gold nanoparticles (NPs) attached were successfully prepared by a facile sputtering deposition technique. Initially, the morphology and crystal structure of the bare α-MnO2 nanorods synthesized via a hydrothermal approach were investigated. Then, the amount of gold NPs at different sputtering times was analyzed. It was confirmed that the amount of the decorated gold NPs increased with the lengthening of the sputtering time until they completely covered the α-MnO2 nanorods. Theoretical calculation results indicated the advantages of the composite structure by showing the enhanced electromagnetic fields around both the bare α-MnO2 nanorods and the gold NP decorated ones. The surface-enhanced Raman scattering (SERS) efficiency of these nanocomposites was evaluated using methylene blue and 4-mercaptobenzoic acid as Raman probe molecules. It was found that the SERS intensity of the substrates strongly depended on the degree of aggregation of the gold NPs. Uniform SERS signals across the entire surface of these samples were obtained. Moreover, a typical chemical toxin, methyl parathion, was effectively detected over a broad concentration range from 1 × 10(-3) to 100 ppm using the gold NP decorated α-MnO2 nanorods, suggesting this hybrid structure is highly valuable for further applications on the rapid detection of organic environmental pollutants.

  5. Dyke swarms and their role in the genesis of world-class gold deposits: Insights from the Jiaodong peninsula, China

    Science.gov (United States)

    Li, Lin; Li, Sheng-Rong; Santosh, M.; Li, Qing; Gu, Yue; Lü, Wen-Jie; Zhang, Hua-Feng; Shen, Jun-Feng; Zhao, Guo-Chun

    2016-11-01

    Jiaodong peninsula, located at the southeastern margin of the North China Craton, is well known for its rich endowment of super-large gold deposits. This region is also characterized by hundreds of intermediate - mafic dykes that cluster into several dyke swarms. In this study, we present zircon U-Pb ages which show that the timing of dyke emplacement as ca. 120 Ma, which followed the crystallization of the (quartz-) diorite porphyry at ca. 130 Ma. These ages coincide with the peak ages reported for magmatism and metallogeny in the central North China Craton. The various ages (2450-2570 and 154 Ma) from the inherited zircon crystals in these rocks suggest that substantial lower to middle crustal basement rocks and Jurassic granitoids were involved during dyke emplacement. The dyke swarms, varying between alkaline and subalkaline, are compositionally low-Si low-Ti lamprophyre and low-Si high-Ti dolerite porphyry in the western of the Jiaodong peninsula, whereas those in the eastern part are composed of both high-Si low-Ti and low-Si high-Ti lamprophyres. These features imply multiple sources for the dykes from convective asthenospheric mantle to ancient enriched lithospheric mantle with magma generation at different depths involving mixture of slab-derived hydrous fluids. The source magmas of the dykes were hydrous and enriched in volatiles as well as ore components, and their evolution occurred under high oxygen fugacity conditions. The relatively rapid emplacement and cooling of the dyke systems enabled the migration of fluids into ore-controlling faults or fractures. We envisage that the dyke swarms played an important role in generating the world-class gold mineralization of Jiaodong.

  6. Colloidal origin of colloform-banded textures in the Paleogene low-sulfidation Khan Krum gold deposit, SE Bulgaria

    Science.gov (United States)

    Marinova, Irina; Ganev, Valentin; Titorenkova, Rositsa

    2014-01-01

    We studied both colloform-banded macro- and micro-textures as well as the composition of electrum from the epithermal Khan Krum (or Ada Tepe) gold deposit, Bulgaria (5 Mt at 5.1 g/t Au + 2.7 g/t Ag) using optical and electron scanning microscopy, vibration spectroscopy, electron micro-probe analysis, and LA-ICP-MS. The individual textural bands differ in grain size, porosity, quartz-to-adularia ratio, and abundance of electrum, pyrite, and scattered dusty opaque micro-inclusions. The individual macro-bands have formed successively via intermittent fault dilation from episodic hydrothermal pulses, as a result of regional extension and most likely originated from colloidal solutions formed by vigorous boiling during rapid pressure drop and supersaturation with respect to amorphous silica in a closed or quasi-closed hydrothermal system. Electrum is highly concentrated in the finest quartz-adularia colloform micro-bands, which fill joints with widths up to 1-2 mm. We presume that the joints have filled in with more concentrated colloidal solutions than those in the macro-bands, most likely due to extreme boiling of fluids in open or quasi-open hydrothermal system. Electrum in the micro-bands forms transverse dendrite- and chain-like aggregates as well as oval clots along the banding, all of globular morphology. We explain these locations of electrum with reorientation of aggregated electrum globules during plastic deformation of a mixed electrum-silicate gel and in result from the consequent crystallization of silicates. At the same time, electrum is not present in pores and cracks of syneresis, which indicates that it had not been a soluble phase at the time of syneresis, rather colloidal particles. Electrum also forms dense sprinkles of globular morphology deposited in open space on the surfaces of some quartz-adularia bands, due to a condensation of gaseous phase, separated during the boiling of fluids. We found that the electrum-rich quartz-adularia micro

  7. Strong Paramagnetism of Gold Nanoparticles Deposited on a Sulfolobus acidocaldarius S Layer

    Science.gov (United States)

    Bartolomé, J.; Bartolomé, F.; García, L. M.; Figueroa, A. I.; Repollés, A.; Martínez-Pérez, M. J.; Luis, F.; Magén, C.; Selenska-Pobell, S.; Pobell, F.; Reitz, T.; Schönemann, R.; Herrmannsdörfer, T.; Merroun, M.; Geissler, A.; Wilhelm, F.; Rogalev, A.

    2012-12-01

    Magnetic properties of Au nanoparticles deposited on an archaeal S layer are reported. X-ray magnetic circular dichroism and superconducting quantum interference device magnetometries demonstrate that the particles are strongly paramagnetic, without any indication of magnetic blocking down to 16 mK. The average magnetic moment per particle is Mpart=2.36(7) μB. This contribution originates at the particle’s Au 5d band, in which an increased number of holes with respect to the bulk value is observed. The magnetic moment per Au atom is 25 times larger than any measured in other Au nanoparticles or any other configurations up to date.

  8. Electrochemical deposition of Te adlayers onto 3D networks of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Montes de Oca, Maria G. [School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS (United Kingdom); Fermin, David J., E-mail: David.Fermin@bristol.ac.u [School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS (United Kingdom)

    2010-12-01

    The controlled electrochemical deposition of atomic layers of Te onto 3D assemblies of Au nanoparticles in acid solution is reported for the first time. Citrated stabilized Au particles of 19.3 {+-} 1.2 nm diameter were assembled into two- and three-dimensional networks via electrostatic layer-by-layer adsorption employing poly-L-lysine (PLL) on In-doped SnO{sub 2} (ITO) electrodes. Atomic force microscopy (AFM) and electrochemical measurements showed that the 3D assemblies consist of an open network of electrically interconnected nanoparticles. Electrochemical studies in the presence of TeO{sub 2} show two distinct features associated with one and two atomic adlayers of Te selectively deposited onto the Au nanocrystals. Detailed analysis of the electrochemical responses as a function of the surface corrugation showed that the average Te coverage on a single Au nanoparticle is close to those observed on extended Au surfaces. The results demonstrate that the surface composition of each individual particle in the 3D assembly can be electrochemically modified at the atomic level. The implications of these findings for the design of electrocatalytically active ultrathin composites are briefly discussed.

  9. Volatile Evolution and Anhydrite-Bearing Dacite, Yanacocha Gold Deposit, Cajamarca, Peru: Relevance for the Sulfur Budget

    Science.gov (United States)

    Chambefort, I. S.; Dilles, J. H.

    2006-12-01

    Magmatic water, sulfur and chlorine evolved during volcanic eruptions have important climactic effects, but during passive degassing these volatiles may transport metals and produce hydrothermal ore deposits. At the Yanacocha Mine, we are examining the volatile evolution of the Miocene andesitic to dacitic volcanic rocks (ca 20 to 8 Ma). High sulfidation epithermal deposits contain >50 Moz of gold in oxides with additional deeper sulfide resources containing >5 Mt of copper. Large volumes (>10 km3) of rock are hydrothermally altered by sulfate-rich and low pH fluid to quartz, quartz-alunite, quartz-pyrophyllite, illite. Pyrite (1-5 vol.%), native sulfur, covellite, enargite and chalcopyrite constitute reduced S-species. In total, at least 500 M tonnes of sulfur were added during alteration. The San Jose ignimbrite (SJI) erupted 30 km3 magma in two cooling units at 11.50 and 11.28 Ma, and immediately predates the bulk of gold mineralization at about 10.80 Ma (Longo, 2005). This hornblende- plagioclase dacitic magma is highly oxidized with fO2 ≍ 2 NNO. Low-Al2O3 (~7 wt.%), and high- Al2O3 (~12 wt.%) amphiboles coexist in most of the samples. Plag-hbl thermobarometry on low-Al content amphibole yields ca. 1.5-2 kb and 800°C. High-Al pargasitic hornblende forms sparse crystals up to 1 cm long that often show resorption or oxide rims associated with oxyhornblende breakdown. Apatite is an inclusion but generally not plagioclase or oxide. These petrographic relations suggest that the high-Al hornblende is the liquidus phase (at 950 to 1000°C, PH2O > 3 kb) in an andesitic or basaltic magma. The high-Al amphibole in two samples contains anhydrite inclusions, one with >5 vol.% anhydrite associated with apatite having up to 1.2 wt.% SO3. Comparison of these data with experimental sulfate solubilities at NNO+2 suggests the andesitic or basaltic melt dissolved at least 1000 ppm S. One low-Al amphibole contains anhydrite, demonstrating that the cooler dacite magma was also

  10. Two series of copper-gold deposits in the middle and lower reaches of the Yangtze River area (MLYRA) and the hydrogen, oxygen, sulfur and lead isotopes of their ore-forming hydrothermal systems

    Institute of Scientific and Technical Information of China (English)

    周涛发; 袁峰; 岳书仓; 赵勇

    2000-01-01

    Based on studies on the geological characteristics of the copper-gold deposits in the middle and lower reaches of the Yangtze River area (MLYRA) and their hydrogen, oxygen, sulfur and lead isotope compositions, it is concluded that there existed two series of copper-gold deposits. They are evolutional products of two ore-forming hydrothermal systems in different geodynamic settings and geological era. Series I is stratiform or stratabound copper-gold deposits. These deposits were formed by submarine exhalation and sedimentation of hydrothermal solutions in Her-cynian tensional tectonic environment after bot brine ascending along contemporaneous faults and exhaled into the sea-floor. Series II consists of copper-gold deposits related to medium and acidic magmatic intrusions. Their mineralizations took place in Yanshanian in a tensional or a transitional period to the tensional tectonic environment from the composite of the tethys tectonic regime and the Paleo-Pacific ocean tectonic regime, as well as in

  11. Laser probe 40Ar/39Ar dating for quartz from auriferous quartz veins in the Shihu gold deposit, western Hebei Province, North China

    Institute of Scientific and Technical Information of China (English)

    CAO Ye; LI Shengrong; ZHANG Huafeng; AO Chong; LI Zhenzhen; LIU Xiaobin

    2010-01-01

    The Shihu gold deposit is situated in the central shear zone of the Meso-Cenozoic Fuping metamorphic core complex in the middle-northern part of the Taihang Mountains. This kind of gold deposits named after 'Shihu type' widely occurs in this region. Gold-bearing quartz veins are their most important industrial orebodies. Detailed laser 40Ar/39Ar geochronology of the mineralized quartz veins in the study area reveals details of its tectono-magmatic history. The 40Ar/39Ar ages for the quartz are between 134.4 Ma and 155.9 Ma with a mean age of 141±4 Ma on the isochron line and 139±7 Ma on the inverse isochron line, respectively, which is interpreted to be the best estimate of the crystalline age of the quartz veins. The gold mineralization was most likely related to an underplating event that took place in the northern part of the Taihang Mountain at ca. 140 Ma. The timing of gold mineralization in the area is similar to those observed in other major gold-producing provinces in the NCC. This episode is simultaneous with those in the eastern NCC, indicative of a widespread late Yanshanian metallogenic event that was a response either to the subduction of the Izanagi-Pacific plate beneath eastern China or to the removal of the Early Cretaceous lithosphere in the eastern NCC. The ore-forming material sources may be the Early Precambrian metamorphic basement, instead of intermediate-acid rock bodies and dykes.

  12. Chandra Locates Mother Lode of Planetary Ore in Colliding Galaxies

    Science.gov (United States)

    2004-01-01

    NASA's Chandra X-ray Observatory has discovered rich deposits of neon, magnesium, and silicon in a pair of colliding galaxies known as The Antennae. When the clouds in which these elements are present cool, an exceptionally high number of stars with planets should form. These results may foreshadow the fate of the Milky Way and its future collision with the Andromeda Galaxy. "The amount of enrichment of elements in The Antennae is phenomenal," said Giuseppina Fabbiano of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. at a press conference at a meeting of the American Astronomical Society in Atlanta, Ga. "This must be due to a very high rate of supernova explosions in these colliding galaxies." Fabbiano is lead author of a paper on this discovery by a team of U.S. and U.K. scientists that will appear in an upcoming issue of The Astrophysical Journal Letters. When galaxies collide, direct hits between stars are extremely rare, but collisions between huge gas clouds in the galaxies can trigger a stellar baby boom. The most massive of these stars race through their evolution in a few million years and explode as supernovas. Heavy elements manufactured inside these stars are blown away by the explosions and enrich the surrounding gas for thousands of light years. "The amount of heavy elements supports earlier studies that indicate there was a very high rate of relatively recent supernovas, 30 times that of the Milky Way," according to collaborator Andreas Zezas of the CfA. Animation of Colliding Galaxies Animation of Colliding Galaxies The supernova violence also heats the gas to millions of degrees Celsius. This makes much of the matter in the clouds invisible to optical telescopes, but it can be observed by an X-ray telescope. Chandra data revealed for the first time regions of varying enrichment in the galaxies – in one cloud magnesium and silicon are 16 and 24 times as abundant as in the Sun. "These are the kinds of elements that

  13. Decoration of silica nanowires with gold nanoparticles through ultra-short pulsed laser deposition

    Science.gov (United States)

    Gontad, F.; Caricato, A. P.; Cesaria, M.; Resta, V.; Taurino, A.; Colombelli, A.; Leo, C.; Klini, A.; Manousaki, A.; Convertino, A.; Rella, R.; Martino, M.; Perrone, A.

    2017-10-01

    The ablation of a metal target at laser energy densities in the range of 1-10 TW/cm2 leads to the generation of nanoparticles (NP) of the ablated material. This aspect is of particular interest if the immobilization of NPs on three-dimensional (3D) substrates is necessary as for example in sensing applications. In this work the deposition of Au NP by irradiation of a Au bulk target with a sub-picosecond laser beam (500 fs; 248 nm; 10 Hz) on 2D (silica and Si(100)) and 3D substrates (silica nanowire forests) is reported for different number of laser pulses (500, 1000, 1500, 2000, 2500). A uniform coverage of small Au NPs (with a diameter of few nm) on both kinds of substrates has been obtained using a suitable number of laser pulses. The presence of spherical droplets, with a diameter ranging from tens of nm up to few μm was also detected on the substrate surface and their presence can be explained by the weak electron-phonon coupling of Au. The optical characterization of the samples on 2D and 3D substrates evidenced the surface plasmon resonance peak characteristic of the Au NPs although further improvements of the size-distribution are necessary for future applications in sensing devices.

  14. Natural Radioactivity at the Sin Quyen Iron-Oxide-Copper-Gold Deposit in North Vietnam

    Science.gov (United States)

    Nguyen, Dinh Chau; Khanh, Phon Le; Jodłowski, Paweł; Pieczonka, Jadwiga; Piestrzyński, Adam; Van, Hao Duong; Nowak, Jakub

    2016-12-01

    The field radiometric and laboratory measurements were performed at the Sin Quyen copper deposit in North Vietnam. The field gamma-ray spectrometry indicated the concentration of uranium ranging from 5.5 to 87 ppm, thorium from 5.6 to 33.2 ppm, and potassium from 0.3 to 4.7%. The measured dose rates ranged from 115 to 582 nGy/h, the highest doses being at the copper ore. Concentrations in the solid samples were in the range of 20-1700 Bq/kg for uranium, 20-92.7 Bq/kg for thorium, and 7-1345 Bq/kg for potassium. The calculated doses were from 22 to 896 nGy/h; both measured and calculated dose rates are mostly related to uranium. Concentrations of radium in water samples were below 0. 17 Bq/L. Uranium in water samples was significantly higher than the hydrogeological background; the maximum of 13 Bq/L was at the waste zone pool, but neither radium nor uranium were present in tap water. Radon concentration in the dwelling air was from 42 to 278 Bq/m3 for 222Rn and from 8 to 193 Bq/m3 for 220Rn. The estimated committed dose rates were principally related to 222Rn concentration and ranged from 1.1 to 8.1 mSv/y.

  15. Natural Radioactivity at the Sin Quyen Iron-Oxide-Copper-Gold Deposit in North Vietnam

    Directory of Open Access Journals (Sweden)

    Nguyen Dinh Chau

    2016-12-01

    Full Text Available The field radiometric and laboratory measurements were performed at the Sin Quyen copper deposit in North Vietnam. The field gamma-ray spectrometry indicated the concentration of uranium ranging from 5.5 to 87 ppm, thorium from 5.6 to 33.2 ppm, and potassium from 0.3 to 4.7%. The measured dose rates ranged from 115 to 582 nGy/h, the highest doses being at the copper ore. Concentrations in the solid samples were in the range of 20-1700 Bq/kg for uranium, 20-92.7 Bq/kg for thorium, and 7-1345 Bq/kg for potassium. The calculated doses were from 22 to 896 nGy/h; both measured and calculated dose rates are mostly related to uranium. Concentrations of radium in water samples were below 0. 17 Bq/L. Uranium in water samples was significantly higher than the hydrogeological background; the maximum of 13 Bq/L was at the waste zone pool, but neither radium nor uranium were present in tap water. Radon concentration in the dwelling air was from 42 to 278 Bq/m3 for 222Rn and from 8 to 193 Bq/m3 for 220Rn. The estimated committed dose rates were principally related to 222Rn concentration and ranged from 1.1 to 8.1 mSv/y.

  16. 辽东半岛滨海砂金矿成矿规律%Metallogenic Regularity of the Coastal Gulch-gold Deposit in Liaodong Peninsula

    Institute of Scientific and Technical Information of China (English)

    刘长纯; 姚志宏; 孙鹏慧

    2016-01-01

    Liaodong peninsula coastal gulch-gold mine is not development,less resources,in order to provide the theoretical reference for the prospecting work of coastal gulch-gold deposit in Liaodong pen-insula,the metallogenic conditions of the coastal gulch-gold deposit are analyzed,the results show that:①the new archean strata and ancient proterozoic strata are developed in Liaodong peninsula,intrusive rocks and native gold deposits (points)with the characteristics of more material source and multi-stage forma-tion;②the climatic conditions along the Yellow sea coast are conducive to weathering and erosion,with more rainfall and large rive transport capacity,a large number of ore-forming materials are transported for the gulch-gold deposit;③the favorable metallogenic environment for the formation of coastal gulch-gold deposits is provided by the abundant land physiognomy,sea bottom physiognomy,coastal types physiogno-my and Quaternary type physiognomy with alluvial-diluvial causes;④the new tectonic movement is mainly for overall lift long up,which caused the the peninsula suffered the strong erosion in the entire Quaterna-ry,so,the sufficient material source for the gulch-gold deposit is provided.Based on the above analysis re-sults,the metallogenic material source,metallogemnic dynamic and metallogenic environment are dis-cussed from the aspects of ore-forming material supply conditions,climate and hydrodynamic conditions and sedimentary environment.The above study results can provide some reference for the prospecting work of coastal gulch-gold deposit in Liaodong peninsula.%辽东半岛滨海砂金矿不发育、资源量少,为进一步加强寻找滨海砂金矿,对滨海砂金矿的成矿条件进行了分析,结果表明:①区内具有新太古、古中元古代地层,侵入岩和原生金矿床(点)具有多物质来源和形成的多阶段性;②半岛黄海沿岸的气候条件有利于风化剥蚀作用的进行,伴随着降雨较多

  17. One-pot deposition of gold on hybrid TiO{sub 2} nanoparticles and catalytic application in the selective oxidation of benzyl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Mehri, Afef [University Tunis El-Manar, Laboratoire de Chimie des Matériaux et Catalyse, Tunis (Tunisia); Kochkar, Hafedh, E-mail: h_kochkar@yahoo.fr [University Tunis El-Manar, Laboratoire de Chimie des Matériaux et Catalyse, Tunis (Tunisia); Laboratoire de Valorisation des Matériaux Utiles, Centre National de Recherches en Sciences des Matériaux, Technopôle de Borj-Cedria, 2050 Hammam-Lif (Tunisia); Berhault, Gilles [Institut de Recherches sur la Catalyse et de l' Environnement de Lyon, CNRS-Université Lyon I, 69100 Villeurbanne (France); Cómbita Merchán, Diego Fernando; Blasco, Teresa [Instituto de Tecnología Química (UPV-CSIC), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos, s/n, Valencia (Spain)

    2015-01-15

    One-pot deposition of Au onto TiO{sub 2} has been achieved through directly contacting gold (III) salt with nanosized functionalized TiO{sub 2} support initially obtained by sol–gel process using titanium isopropoxide and citric acid. Citrate groups act as functional moieties able to directly reduce the Au salt avoiding any further reducing treatment. Various gold salts (NaAuCl{sub 4}·2H{sub 2}O or HAuCl{sub 4}·3H{sub 2}O) and titanium to citrate (Ti/Cit) molar ratios (20, 50 and 100) were used in order to study the effect of the nature of the precursor and of the citrate content on the final Au particle size and catalytic properties of the as-obtained Au/TiO{sub 2} materials. Au/(TiO{sub 2}){sub x}(Cit){sub 1} catalysts characterization was performed using N{sub 2} adsorption–desorption, ICP-AES, X-ray diffraction and TEM. The effect of the Ti/Cit molar ratio and of the gold precursor was evaluated. The selective oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) was studied as a model reaction. Kinetic analysis showed that the catalytic reaction rate was pseudo first-order and the values of activation energy have been reported. Results showed that the functionalization of TiO{sub 2} by citrate allows tuning the size of the Au nanoparticles deposited onto TiO{sub 2} as well as their morphology. Citrate also strongly enhances the benzyl alcohol oxidation through the control of the size and morphology of gold nanoparticles. - Highlights: • One-pot deposition of Au onto TiO{sub 2} has been achieved. • Citrates act as active sites for selective deposition and reduction of gold. • The presence of citrates influences the size and the morphology of gold NPs. • Au NPs with well-defined morphologies were obtained for Cit/Ti molar ratio of 100. • The selective oxidation of benzyl alcohol was studied as a model reaction.

  18. 甘肃拾金坡金矿床成因:来自40Ar/39Ar定年、成矿流体及H-O-S同位素证据%Ore Genesis of the Shijinpo Gold Deposit in Gansu Province, NW China:40Ar/39Ar Dating, Ore-Forming Fluid and H-O-S Isotopes Constrains

    Institute of Scientific and Technical Information of China (English)

    朱江; 吕新彪; 莫亚龙; 曹晓峰; 陈超

    2013-01-01

    甘肃拾金坡金矿床是北山造山带南部的一处重要中型金矿床.矿体以石英脉和蚀变岩形式产出,受东西向断裂控制,赋矿围岩为早泥盆世拾金坡二长花岗岩.矿石中主要金属硫化物为黄铁矿及少量方铅矿、闪锌矿和磁黄铁矿.石英脉两侧花岗岩发生强烈的硅化、黄铁绢英岩化和绿泥石化.热液蚀变绢云母40Ar/39Ar坪年龄为(364.6±3)Ma,表明成矿作用发生在晚泥盆世.矿石石英中流体包裹体可分为早晚两期:早期流体包裹体群包含不同气液比水溶液包裹体和含CO2包裹体,指示成矿过程存在流体沸腾作用,其均一温度集中在280~325℃,盐度(ω(NaCl))为7.86%~9.21%;晚期流体包裹体群只发育水溶液包裹体,均一温度集中于160~230℃,盐度为9.47%~11.10%.成矿流体属中温低盐度、富CO2流体.流体从早阶段演化到晚阶段,温度降低约100℃,压力由约113 MPa骤减到约11 MPa.流体包裹体的δ18 OH2O值为1.39‰~3.39‰,δD值为-71‰~-99‰.氢氧投图中,石英脉和蚀变岩样品构成良好的线性关系,暗示初始成矿流体主要来自变质热液,晚期有强烈大气降水加入.矿石金属硫化物δ34S值变化范围为4.44‰~11.33‰,峰值为8‰~9‰,呈塔式分布.与区域S同位素资料对比分析表明,石英脉型矿石S主要来自前寒武系基底,蚀变岩型矿石S更多地继承了花岗岩围岩S.综合分析认为,拾金坡金矿床属于造山型金矿,形成于造山晚期挤压—伸展转换环境.%The Shijinpo gold deposit is an important middle-size lode gold deposit in the Beishan orogenic belt, northwestern China. The gold mineralization is hosted in the early Devonian granite and consists primarily of auriferous quartz veins that are controlled by the EW-trending faults. Wall-rock alteration is dominated by sericite +quartz + sulfide assemblages in close proximity of gold veins. The pyrite is the predominant sulfide mineral

  19. High arsenic coals related to sedimentary rock-hosted gold deposition in southwestern Guizhou Province, People`s Republic of China

    Energy Technology Data Exchange (ETDEWEB)

    Belkin, H.E.; Warwick, P.D.; Finkelman, R.B. [Geological Survey, Reston, VA (United States); Zheng, B. [Chinese Academy of Sciences, Guiyang, Guizhou (China); Zhou, D. [Autonomous Prefecture Anti-Epidemic Station of Southwest Guizhou Province (China)

    1998-12-31

    The rural population of southwestern Guizhou Province, China uses locally derived coal for domestic heating, cooking, and drying of various food stuffs by un-vented stoves. Coal became the dominant fuel source after deforestation earlier this century. Approximately 40 years ago, symptoms of arsenic poisoning, in some cases extreme, appeared in isolated, rural populations. More than 3,000 cases of arsenosis have been documented, whereas the affected population exceeds 10,000. Chemical analyses show that selected coals are extremely enriched in As and contain high concentrations of other trace elements deleterious to health. Southwestern Guizhou Province is underlain by an extensive thickness of Upper Paleozoic and Lower Mesozoic sedimentary rocks. The Permian, although aerially much less extensive, contains coal-bearing argillaceous sedimentary rocks of the Longtan Formation. The predominantly rural population in this mountainous region obtains most of their coal from many, very small mines operated locally. Southwestern Guizhou Province is also the site of extensive, mostly small-scale, gold mining from discontinuous sedimentary rock-hosted, Carlin-type gold deposits. Gold is currently being mined from areas that contact high-arsenic coals. The structural complexity of the area as well as the gold-As- rich coal association suggests that coal zones containing high As are probably as irregular and discontinuous as the gold deposits. The local public health officials have instituted a program of testing the coal being mined for its high As concentration. A collaborative study between the US Geological Survey and the Key Laboratory of Environmental Geochemistry in Guiyang, Chinese Academy of Science is investigating the origin, occurrence, and distribution of arsenic in these coals. The goal is to be able to understand the petrogenesis in order to be able to predict and delineate arsenic-rich coals or zones.

  20. Time distribution of the main Brazilian mineral deposits. 2: metallogenic epochs; Distribuicao no tempo geologico dos principais depositos minerais brasileiros. 2: epocas metalogeneticas

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, Joao C. [Parana Univ., Curitiba, PR (Brazil). Dept. de Geologia]. E-mail: jcbiondi@setuva.geologia.ufpr.br

    1999-12-01

    The metallogenic epochs of the main mineral deposit groups were defined with base on the ore's of the 194 main Brazilian mineral deposits. Mineral deposits are rare on epochs that: precede the beginning of juvenile accretion peak periods, and/or of cooling of rocks formed during each of the main brazilian thermo-tectonic events. Deposits are more frequent on epochs that are coincident or immediately younger than these peak periods. The most important metallogenic epoch, with about 30% of the selected deposits, is between 50 Ma and the Recent, and corresponds to the formation of supergenic and/or residual and placer deposits. Brazilian's volcanogenic (VHMS), Mississippi Valley (MTV) and mesothermal gold-lode deposits have discordant ages as compared with their equivalents in other countries, while deposits believed to be SEDEX have concordant ages. With the exception of Urucum, the primary iron and manganese ores of brazilian deposits are Archean. Primary tin deposits from Amazonas, Amapa and Goias State cluster between 1500 and 2300 Ma. Tin deposits from Rondonia and Mato Grosso are more recent and most formed between 1000 and 1600 Ma, in sequence with the other groups of tin deposits. Uranium deposits vary on genetic model and ages, due to the mobility of the element in all geologic environments. Most part of Brazilian deposits of phosphate, titanium, niobium, Rare Earths, diamond in kimberlites and of amethyst formed during the Mesozoic, and arte genetically related to the alkaline and basaltic magmatism that affected the brazilian territory in this period. Gemstone (tourmaline and aquamarine), talc and magnesite deposits are more frequent in the Brasiliano period. Gipsite, silvite and barite occur in Senonian to Aptian evaporites. (author)

  1. Evidence of Plasmonic Induced Photocatalytic Hydrogen Production on Pd/TiO2 Upon Deposition on Thin Films of Gold

    KAUST Repository

    Khan, M. A.

    2017-02-28

    H2-production from renewables using sunlight is probably the holy grail of modern science and technology. Among the many approaches for increasing reaction rates, by increasing light absorption, plasmonic materials are often invoked. Yet, most plasmonic metals on semiconductors are also good for Schottky barrier formation. In this work, we are presenting evidences of de-coupling the plasmonic from Schottky effects on photoreaction. To conduct this we have systematically changed the under-layer gold film thickness and associated particle size. On top of the thin film layer, we have deposited the exact amount of a prototypical Schottky-based photo-catalyst (Pd/TiO2). We found up to 4 times increase in the H2-production rate at a critical Au film thickness (8 nm-thick). Below this thickness, the plasmonic response is not too strong while above it, the PR decays in favor of the Drude absorption mode. The reaction requires the presence of both UV (to excite the semiconductor) and visible light (to excite Au particles) in order to obtain high hydrogen production, 800 µmol/gCatal.min (probably the highest direct hydrogen (not current) production rate reported on a performing catalyst). The enhancement origin is quantitatively traced to its computed electric field strength (EFS). Adding a dielectric (SiO2) in between the Au thin layer and the catalyst exponentially decreased the reaction rate and EFS, with increasing its thickness. This work indicates the possibility of making an active and stable photo-catalyst from fundamental concepts yet further progress on the structural (technological) front is needed to make a practical catalyst.Graphical abstract

  2. Geology and mineral deposits of the Jabal ash Shumta quadrangle, Kingdom of Saudi Arabia

    Science.gov (United States)

    Hummel, C.L.; Ankary, Abdullah O.

    1972-01-01

    Rocks, structures, and mineral deposits which are the result of both the older Halaban petro-tectonic cycle and the younker Najd Wrench Fault deformation are present in the Ash Shumta area. Northward-trending belts of granitic rocks and folded, layered metavolcanic and metasedimentary rocks of the Halaban Formation which they intrude represent the effects of the Halaban cycle. These older rocks are everywhere transected and deformed by northwestward- and northeastward-striking fractures and strike-slip faults and by eastward-striking fractures and fracture-controlled silicic dikes which belong to the Najd Wrench Fault deformation. Several kinds of epigenetic mineral deposits of hydrothermal origin are present throughout the Ash Shumta area. All occur in or ape closely associated with structures of the Najd Wrench Fault deformation. The mineralization which produced the deposits is thought to have taken place during the period of deformation which produced the Najd Wrench Fault structures. The hydrothermal deposits include many metalliferous quartz veins most of which occur in three mineralized areas: two major areas at Jabal Ash Shumta and Jabal El Khom in the northern half of the quadrangle and a minor area along Wadj al Boharah in the southeastern part of the quadrangle. The metalliferous lodes possess the only economic potential in the area of the Jabal Ash Shumta quadrangle. These lodes consist mainly of gold and base metal-bearing quartz veins, some of which were mined for gold in ancient times. The mineralized area at Jabal Ash Shumta has the best of these veins. Higher temperature veins with wolframite as a major constituent and beryl as a minor one occur in a granite cupola in the eastern part of the El Khom area. These veins have altered, gneissen-like wall rocks. Although the grade of the veins is low at the surface, the made could increase at depth. The tungsten-bearing veins and El Khom area possess the greatest economic promise in the Jabal Ash Shumta

  3. Experimental study of gold activation-transportation in the process of potash metasomatism-alteration——North China platform gold deposit taken as an example

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical reactions of plagioclase, biotite and their singleminerals, as well as a mineral mixture of (plagioclase +biotite+quartz), with KCl and (KCl+KHCO3) solutions were carried out at 150400℃ and 5080 MPa. Experiments show that alkaline fluid promotes plagioclase’s changing into potash feldspar, while acid fluid helps plagioclase, potash feldspar and biotite alteration form chlorite and sericite. After chemical reaction the acidity-alkalinity of solutions often changes reversely. It was observed that gold dissolved from the tube wall and recrystallized on the surfaces of biotite and pyrite. Therefore the transportation and enrichment of gold are related to the elementary effect of the fluid-mineral interfaces. Fe3+-Fe2+, as an oxidition-reduction agent, and volatile components Cl? and CO2 play important roles in the reaction process.

  4. Experimental study of gold activation-transportation in the process of potash metasomatism-alteration ——North China platform gold deposit taken as an example

    Institute of Scientific and Technical Information of China (English)

    WANG; Yurong; HU; Shouxi

    2001-01-01

    Chemical reactions of plagioclase, biotite and their single minerals, as well as a mineral mixture of (plagioclase +biotite+quartz), with KCl and (KCl+KHCO3) solutions were carried out at 150400℃ and 5080 MPa. Experiments show that alkaline fluid promotes plagioclase’s changing into potash feldspar, while acid fluid helps plagioclase, potash feldspar and biotite alteration form chlorite and sericite. After chemical reaction the acidity-alkalinity of solutions often changes reversely. It was observed that gold dissolved from the tube wall and recrystallized on the surfaces of biotite and pyrite. Therefore the transportation and enrichment of gold are related to the elementary effect of the fluid-mineral interfaces. Fe3+-Fe2+, as an oxidition-reduction agent, and volatile components Cl? and CO2 play important roles in the reaction process.

  5. Iron oxide copper-gold deposits in the Islamic Republic of Mauritania (phase V, deliverable 79): Chapter M in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    Science.gov (United States)

    Fernette, Gregory

    2015-01-01

    Mauritania hosts one significant copper-gold deposit, Guelb Moghrein and several occurrences, which have been categorized as iron oxide copper-gold (IOCG) deposits but which are atypical in some important respects. Nonetheless, Guelb Moghrein is an economically significant mineral deposit and an attractive exploration target. The deposit is of Archean age and is hosted by a distinctive metacarbonate rock which is part of a greenstone-banded iron formation (BIF) package within a thrust stack in the northern part of the Mauritanide Belt. The surrounding area hosts a number of similar copper-gold occurrences. Based on the characteristics of the Guelb Moghrein deposit and its geologic environment, five tracts which are considered permissive for IOCG type mineralization similar to Guelb Moghrein have been delineated.

  6. Recycling and utilisation of industrial solid waste: an explorative study on gold deposit tailings of ductile shear zone type in China.

    Science.gov (United States)

    Liu, Rui; Huang, Fei; Du, Runxiang; Zhao, Chunming; Li, Yongli; Yu, Haoran

    2015-06-01

    Tailings are solid waste arising from mineral processing. This type of waste can cause severe damage to the environment during stockpiling as a result of the leaching of something harmful into the ecosystem. Gold deposit of ductile shear zone type is an important type of gold deposit, and the recycling of its tailings has been challenging researchers for a long time. In this article, the characteristics of this type of tailings were systematically studied by using modern technical means. Considering the characteristics of the tailings, clay was selected to make up for the shortcomings of the tailings and improve their performance. Water and raw materials were mixed to produce green bodies, which are subsequently sintered into ceramic bodies at 980 °C~1020 °C (sintering temperature). The results showed that some new kinds of mineral phases, such as mullite, anorthite and orthoclase, appear in ceramic bodies. Furthermore, the ceramic bodies have a surface hardness of 5 to 6 (Mohs scale), and their water absorption and modulus of rupture can meet some technical requirements of ceramic materials described in ISO 13006-2012 and GB 5001-1985. These gold mine tailings can be made into ceramic tiles, domestic ceramic bodies, and other kinds of ceramic bodies for commercial and industrial purposes after further improvements. © The Author(s) 2015.

  7. 金矿床中金与黄铁矿和毒砂的关系%Hydrothermal evolution of gold-bearing pyrite and arsenopyrite from different types of gold deposits

    Institute of Scientific and Technical Information of China (English)

    卢焕章; 朱笑青; 单强; 王中刚

    2013-01-01

    卡林型金矿中的金,以肉眼,甚至在显微镜下都看不到,因而称之为“不可见金”.经过金的物相分析,发现Au与毒砂、黄铁矿有关.进一步的问题是:Au在毒砂、黄铁矿中呈何状态分布,是呈微细的独立矿物?还是类质同象?是以化学键进入毒砂、黄铁矿的晶格?还是吸附在其表面?进一步的研究表明,世界上其他类型金矿,如浊积岩型金矿、造山带内太古代绿岩带金矿、变质金矿、与火成岩有关的金矿,甚至含金的块状硫化物矿床,其中的金除了以自然金(可见金)产出外,在黄铁矿、毒砂、辉锑矿、雄黄等硫化物中还含有不可见金.从不可见金到可见金,需经过热液蚀变作用,在高As条件下,温度和硫逸度的升高,可溶出不可见金,在温度下降和还原条件下,Au以可见金形式存在于蚀变环带中.这种从不可见金到可见金的转换过程,反映了Au、As、S以及Fe等元素的地球化学特征.金矿中的黄铁矿和毒砂具有相似的结构,包括在其原始生长的晶体中含有不可见金,并且在稍后的成矿阶段内形成赋存有可见金的蚀变环带.蚀变环带以As含量高为特征,并且,后期的可见金是沿裂隙或毒砂与黄铁矿的粒间分布.可见金是热液活化了矿物内的不可见金而形成的.%This study investigates the microstructures,geochemistry,and hydrothermal evolution of gold-bearing pyrite and arsenopyrite from Carlin type (both in the USA and China),turbidite hosted gold deposits of China,intrusion related gold deposits,epithermal gold deposits and six orogenic gold deposits in the Archean Eastern Goldfields Province,Western Australia.Scanning electron microscope (SEM),EPMA,and LA-ICP-MS analyses show that the gold-bearing pyrite and arsenopyrite possess a number of similar textural features,including the occurrence of invisible gold within initial phases of growth,and later-stage visible gold associated with alteration rims

  8. The influence of spreading rate, basement composition, fluid chemistry and chimney morphology on the formation of gold-rich SMS deposits at slow and ultraslow mid-ocean ridges

    Science.gov (United States)

    D. Knight, Robert; Roberts, Stephen; P. Webber, Alexander

    2017-09-01

    Seafloor massive sulphide (SMS) deposits are variably enriched in precious metals including gold. However, the processes invoked to explain the formation of auriferous deposits do not typically apply to mid-ocean ridge settings. Here, we show a statistically significant, negative correlation between the average gold concentration of SMS deposits with spreading rate, at non-sedimented mid-ocean ridges. Deposits located at slow spreading ridges (20-40 mm/a) have average gold concentrations of between 850 and 1600 ppb; however, with increasing spreading rate (up to 140 mm/a), gold concentrations gradually decrease to between 50 and 150 ppb. This correlation of gold content with spreading rate may be controlled by the degree and duration of fluid-rock interaction, which is a function of the heat flux, crustal structure (faulting) and the permeability of the source rocks. Deposits at ultraslow ridges, including ultramafic-hosted deposits, are particularly enriched in gold. This is attributed to the higher permeability of the ultramafic source rocks achieved by serpentinisation and the inherent porosity of serpentine minerals, combined with relatively high gold concentrations in peridotite compared with mid-ocean ridge basalt. Variations in fluid chemistry, such as reducing conditions and the potential for increased sulphur availability at ultramafic-hosted sites, may also contribute to the high concentrations observed. Beehive chimneys, which offer more favourable conditions for gold precipitation, may be more prevalent at ultramafic-hosted sites due to diffuse low-velocity venting compared with more focussed venting at basalt-hosted sites.

  9. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone—Hosted Gold Deposit and Discovery of Melt Inclusions

    Institute of Scientific and Technical Information of China (English)

    李兆麟; 翟伟; 等

    2002-01-01

    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated falut mylonite zone of the Sinian-Silurian metamorphic rock series.In this study there have been discovered melt inclusions,fluid-melt inclusions and organic inclusions in ore-bearing ruartz veins of the ore deposit and mylonite for the first time.The homogenization temperatures of the various types of inclusions are 160℃,180-350℃,530℃and 870℃ for organic inclusions,liquid inclsions two-phase immiscible liquid inclusions and melt inclusion,respectively,Ore fluid is categoriezed as the neutral to basic K+-Ca2+-Mg2+-Na+-SO42--HCO3-Cl- system.The contents of trace gases follow a descending order of H2O>CO2>CH4>(orCO>C2H2>C2H6>O2>N2.The concentrations of K+,Ca2+,SO42-,HCO3-,Cl-,H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in from different levels of the gold deposit.This is significant for deep ore prospecting in the region.Daughter minerals in melt inclusions were analyzed using SEM.Quartz,orthoclase,wollastonite and other silicate minerals were identified.They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins.Sedimentary metamophic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism,which possess melt-soulution characteristics.Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  10. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone-Hosted Gold Deposit and Discovery of Melt Inclusions

    Institute of Scientific and Technical Information of China (English)

    李兆麟; 翟伟; 李文; 石贵勇; 文拥军

    2002-01-01

    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated fault mylonite zone of the Sinian-Silurian metamorphic rock series. In this study there have been discovered melt inclusions, fluid-melt inclusions and organic inclusions in ore-bearing quartz veins of the ore deposit and mylonite for the first time. The homogenization temperatures of the various types of inclusions are 160℃, 180 - 350℃, 530℃ and 870℃ for organic inclusions, liquid inclusions, two-phase immiscible liquid inclusions and melt inclusions, respectively. Ore fluid is categorized as the neutral to basic K+ -Ca2+ -Mg2+ -Na+ - SO2- 4-HCO3-Cl- system. The contents of trace gases follow a descending order of H2O>CO2>CH4>(or < ) H2>CO>C2H2>C2I-I6>O2>N2.The concentrations of K , Ca2 + ,SO2-4,HCO3-,Cl- H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in ores from different levels of the gold deposit. This is significant for deep ore prospecting in the region. Daughter minerals in melt inclusions were analyzed using SEM. Quartz, orthoclase, wollastonite and other silicate minerals were identified. They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins. Sedimentary metamorphic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism, which possess melt-solution characteristics. Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  11. Chemistry of Selected Core Samples, Concentrate, Tailings, and Tailings Pond Waters: Pea Ridge Iron (-Lanthanide-Gold) Deposit, Washington County, Missouri

    Science.gov (United States)

    Grauch, Richard I.; Verplanck, Philip L.; Seeger, Cheryl M.; Budahn, James R.; Van Gosen, Bradley S.

    2010-01-01

    The Minerals at Risk and for Emerging Technologies Project of the U.S. Geological Survey (USGS) Mineral Resources Program is examining potential sources of lanthanide elements (rare earth elements) as part of its objective to provide up-to-date geologic information regarding mineral commodities likely to have increased demand in the near term. As part of the examination effort, a short visit was made to the Pea Ridge iron (-lanthanide-gold) deposit, Washington County, Missouri in October 2008. The deposit, currently owned by Wings Enterprises, Inc. of St. Louis, Missouri (Wings), contains concentrations of lanthanides that may be economic as a primary product or as a byproduct of iron ore production. This report tabulates the results of chemical analyses of the Pea Ridge samples and compares rare earth elements contents for world class lanthanide deposits with those of the Pea Ridge deposit. The data presented for the Pea Ridge deposit are preliminary and include some company data that have not been verified by the USGS or by the Missouri Department of Natural Resources, Division of Geology and Land Survey (DGLS), Geological Survey Program (MGS). The inclusion of company data is for comparative purposes only and does not imply an endorsement by either the USGS or MGS.

  12. 内蒙古达茂旗哈力齐金矿点特征和找矿前景分析%Deposit Characteristics and Prospecting of Haliqi Gold Deposit in Damaoqi, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    吴兆剑; 韩效忠; 尹金双; 王明太

    2015-01-01

    内蒙古达茂旗哈力齐金矿是新近发现的中-低温热液石英脉-蚀变岩型金矿点,位于华北板块北缘增生带乌德岩浆构造混杂带北侧,矿体呈脉状产于下泥盆统查干合布组二云母板岩-浅变质石英砂岩中.通过对成矿地质背景和矿床地质特征分析,认为矿点受近东西向深大断裂的次级断裂构造控制明显.在成矿条件分析的基础上,结合分量化探测量、高精度磁法和音频大地电磁测量(AMT)等综合信息,认为在已发现金矿化石英脉的深部和两侧具有很好的找矿潜力.%Haliqi gold deposit is an epithermal quartz-vein type gold deposit which has been found in the second-ary fracture of the Wude tectonic mélange belt.The deposit occurred in the epimetamorphic quartzose and mi-ca-slate of lower Devonian Chaganhebu Formation and was controlled by the nearly EW-trending deep faults.On the base of analysing the mineralization geological setting and metallogenic conditions,we use controlled-source audio-frequency magnetotelluric method,high-precision magnetic survey method and partial content geochemi-cal survey method to forecast the gold metallogenetic potentiality.It is suggested that the ends and deep part of the mineralized quartz veins are an important metallogenic prospective area.

  13. Maps showing mineral resource assessment for porphyry and stockwork deposits of copper, molybdenum, and tungsten and for stockwork and disseminated deposits of gold and silver in the Butte 1 degree by 2 degrees Quadrangle, Montana

    Science.gov (United States)

    Elliott, J.E.; Moll, S.H.; Wallace, C.A.; Lee, G.K.; Antweiler, J.C.; Lidke, D.J.; Rowan, L.C.; Hanna, W.F.; Trautwein, C.M.; Dwyer, J.L.

    1993-01-01

    This report documents the assessment for potential occurrences of undiscovered porphyry and stockwork deposits of copper, molybdenum, and tungsten (porphyry Cu-Mo-W) and stockwork and disseminated deposits of gold and silver (disseminated Au-Ag) in the Butte 1 °X2° quadrangle. The Butte quadrangle, in west-central Montana, is one of the best known mineral producing regions in the U.S. Mining districts in the quadrangle, including the world famous Butte or Summit Valley district, have produced a variety of metallic and nonmetallic mineral commodities valued at more than $6.4 billion (at the time of production). Because of its importance as a mineral producing region, the Butte quadrangle was selected for study by the U.S. Geological Survey under the Conterminous United States Mineral Assessment Program (CUSMAP). Under this program, new data on geology, geochemistry, geophysics, geochronology, mineral resources, and remote sensing were collected and synthesized. The field and laboratory studies were supported, in part, by funding from the Geologic Framework and Synthesis Program and the Wilderness Program. The methods used in this resource assessment for porphyry Cu-Mo-W and disseminated Au-Ag deposits in the quadrangle include a compilation of all data, the development of descriptive occurrence models, and the analysis of data using techniques provided by a Geographic Information System (GIS). This map is one of several maps on the Butte 1 °X2° quadrangle. Other deposit types have been assessed for the Butte quadrangle, and maps (U.S. Geological Survey (USGS) Miscellaneous Investigation Series Maps) for each of the following have been prepared: Vein and replacement deposits of gold, silver, copper, lead, zinc, manganese, and tungsten (Elliott, Wallace, and others, 1992a) and skarn deposits of gold, silver, copper, tungsten, and iron (Elliott and others, 1992b ). Other publications resulting from this study include linear features map (Rowan and others, 1991

  14. Photoinduced deposition of gold nanoparticles on TiO2-WO3 nanotube films as efficient photoanodes for solar water splitting

    Science.gov (United States)

    Momeni, Mohamad Mohsen; Ghayeb, Yousef

    2016-06-01

    Gold-modified TiO2-WO3 nanotubes with different amounts of gold were obtained by two methods; photoassisted deposition and one-step electrochemical anodizing method. The morphology, crystallinity and elemental composition were studied by FE-SEM, XRD and EDX. The photoelectrochemical performance was examined under Xe light illumination in 1 M NaOH electrolyte. Characterization of the as-prepared TiO2-WO3 samples indicated that sodium tungstate concentration in anodizing solution significantly influenced the morphology and photoelectrochemical activity of fabricated films. Also, photoelectrochemical characterizations show that the photocatalytic activity of Au/TiO2-WO3 nanotubes was improved as compared with that of bare TiO2-WO3 nanotubes. The experimental results showed that the photocatalytic activities of Au/TiO2-WO3 were significantly affected by the amount of Au nanoparticles. The amount of gold nanoparticles was effectively controlled by time of photoreduction of the chloroauric acid solution. These new photoanodes showed enhanced high photocurrent density with good stability and are a highly promising photoanodes for photocatalytic hydrogen production.

  15. 20th-Century Gold Rush.

    Science.gov (United States)

    Wargo, Joseph G.

    1992-01-01

    Presents Nevada's gold rush activities spurred by technological advancements in search methods. Describes the events that led to the twentieth-century gold rush, the techniques for finding deposits and the geological formation process of disseminated gold deposits. Vignettes present the gold extraction process, cross-section, and profile of a…

  16. Study of Gold Deposition on the Inner Wall of Quartz Capillary%石英毛细管内壁镀金工艺的研究

    Institute of Scientific and Technical Information of China (English)

    王梦兰; 贾法龙; 张礼知

    2015-01-01

    ABSTRACT:Objective To develop feasible gold deposition technology on the inner wall of the quartz capillary, which is used for gas detection and analysis by laser Raman. Methods Gold plating was studied with quartz glass first and an optimal technology was achieved after the determination of condition parameters for hydroxylation, silanization, gold nanoparticles modification and wet plating. Then this process was applied to the quartz capillary after adjustment of relevant parameters. The gilded quartz capillary was used for gas analysis through laser Raman measurements, and the enhancement effect of scattering signals was analyzed. Re-sults The concentration of sodium hydroxide, the flow rate and flow time of solution in the capillary obviously affected the adsorption of gold nanoparticles. The optimal technology for gold plating inside the quartz capillary was as following:5 mol/L NaOH treatment for 1 minˇAPTMS/IPA alkylated modificationˇgold sol process at the flow rate of 0. 8 mL/min for 4 h ˇtreatment with plating liquid containing hydroxylamine hydrochloride for 4 h at the flow rate of 0. 8 mL/min. The gilded capillary was used for gas Raman tests and the relative peak strength of N2 in the air was increased from 148 counts ( without gold plating) to 480 counts. Conclu-sion By the use of gold-deposited quartz capillary, corresponding signals of gas could be effectively enhanced under laser Raman detection, which lays a foundation for the further in-situ Raman analysis of gas.%目的:开发出切实可行的石英毛细管内壁镀金工艺,应用于激光拉曼的气体分析检测中。方法先用石英玻璃片进行镀金工艺研究,经过对羟基化、硅烷化、纳米金颗粒修饰、湿法镀金各步条件参数的确定,获得最佳的镀金工艺方案,再对相关参数进行调整,应用于石英毛细管。将镀金石英毛细管应用于激光拉曼的气体分析测试中,分析其对散射

  17. Process Mineralogy Study on the Oxidized Ore in a Gold Deposit%某金矿床氧化矿石工艺矿物学研究

    Institute of Scientific and Technical Information of China (English)

    杨磊; 史光大; 刘飞燕

    2009-01-01

    The oxidized ore mined from a gold deposit contained 8.1g/t Au,82.5g/t Ag and 0.94%Cu. The gold is mainly occurred as native gold,electrum,the silver is mainly occurred as orgentojarosite,horn-silver,and the copper is mainly occurred as cuprite,tenorite,azurite in the ore. The oxidizing rate of the ore is higher,the mouse-eaten and crevasse are developed,and the permeability of the ore is satisfactory. Therefore,the ore is suitable leaching treatment. However,owing to the content of clay is relatively high,and the oxidized copper minerals are soluble in cyanide solution and resulted in production of Cu(CN)2-3 ion that is an important factor influencing recovery of gold and silver. Thus,a technological flowsheet of desliming-wet pretreatment-cyanide leaching of gold and silver was recommended,so as to realize comprehensive recovery of gold,silver and copper from this kind of ore.%某金矿床氧化矿石含金8.1g/t,含银82.5g/t,含铜0.94%.金主要以自然金、银金矿形式存在,银主要以银铁矾,角银矿形式存在,铜主要以赤铜矿、黑铜矿、蓝铜矿形式存在.矿石氧化率高,孔洞、裂隙发育,渗透性良好,适宜湿法浸出.由于粘土矿物含量高,氧化铜矿物易溶于氰化物溶液,并产生影响金、银回收的Cu(CN)2-3离子,因此推荐采用脱泥→湿法预处理→氰化浸出金、银的工艺流程,综合回收矿石中金、银、铜.

  18. Testing gold nanostructures fabricated by hole-mask colloidal lithography as potential substrates for SERS sensors: sensitivity, signal variability, and the aspect of adsorbate deposition.

    Science.gov (United States)

    Peksa, Vlastimil; Lebrušková, Petra; Šípová, Hana; Štěpánek, Josef; Bok, Jiří; Homola, Jiří; Procházka, Marek

    2016-07-20

    Gold nanoplasmonic substrates with high sensitivity and spectral reproducibility are key components of molecular sensors based on surface-enhanced Raman scattering (SERS). In this work, we used a confocal Raman microscope and several types of gold nanostructures (arrays of nanodiscs, nanocones and nanodisc dimers) prepared by hole-mask colloidal lithography (HCL) to determine the sources of variability in SERS measurements. We demonstrate that significant variations in the SERS signal can originate from the method of deposition of analyte molecules onto a SERS substrate. While the method based on incubation of SERS substrates in a solution containing the analyte yields a SERS signal with low variability, the droplet deposition method produces a SERS signal with rather high variability. Variability of the SERS signal of a single nanoparticle was determined from the statistical analysis of the SERS signal in short-range Raman maps recorded using different sized laser spots produced by means of different objectives. We show that the number of nanoparticles located within the laser spot can be a source of substantial SERS signal variability, especially for high-magnification objectives. We demonstrate that SERS substrates prepared by HCL exhibit high SERS enhancement and excellent homogeneity (about 20% relative standard deviation from short-range maps). The nanocone arrays are shown to provide the highest SERS enhancement, the lowest relative level of fluorescence background, and also slightly better homogeneity when compared with arrays of nanodisc dimers or single nanodiscs.

  19. Visible light activity of pulsed layer deposited BiVO4/MnO2 films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation

    Science.gov (United States)

    Trzciński, Konrad; Szkoda, Mariusz; Sawczak, Mirosław; Karczewski, Jakub; Lisowska-Oleksiak, Anna

    2016-11-01

    Thin films containing BiVO4 and MnO2 deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27-115 nm) were characterized using Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy. Electrochemical methods such as electrochemical impedance spectroscopy, linear voltammetry and chronoamperometry under visible light illumination and in the dark were applied to characterize layers as photoanodes. Simple modification of the BiVO4 + MnO2 layer by drop-casting of small amount of colloidal gold (1.5 × 10-14 mol of GNP on 1 cm2) leads to enhancement of the generated photocurrent recorded at E = 0.5 V vs. Ag/AgCl (0.1 M KCl) from 63 μA/cm2 to 280 μA/cm2. Photocatalytical studies were also exploited towards decomposition of methylene blue (MB). A possible mechanism of MB photodegradation was proposed. The formation of hydroxyl radicals was detected by photoluminescence spectra using terephthalic acid as the probe molecule.

  20. The Isotopic Composition of Noble Gases in Gold Deposits and the Source of Ore-Forming Materials in the Region of North Hebei,China

    Institute of Scientific and Technical Information of China (English)

    王宝德; 牛树银; 孙爱群; 李红阳

    2003-01-01

    The source of ore-forming materials has long been a controversial focus both in metallogenic theory and in ore-searching practice. This study deals with the helium and argon isotopic characteristics of pyrites from 11 gold deposits and some country rocks in the gold mineralizationconcentrated areas within the three mantle-branch structures in the region of North Hebei Province. It is indicated that 3He/4He ratios in the gold deposits are within the range of 0.93 × 10 -6-7.3×10-6,with an average of 3.55 × 10-6; R/Ra =0.66 -4.93,averaging 2.53;40Ar/39Ar ratios vary between 426 and 2073,with the average value of 40Ar being 8.32; and the average of 4He/40Ar ratios is 2.17. 3He/4He ratios in gneiss and granite in the periphery of the mining district are within the range of 0. 001 × 10 -6 _ 0. 55 × 10 -6,reflecting significant differences in their sources. 3 He and 4 He fall near the mantle,as is shown in the He concentration diagram. Studies have shown that the ore-forming materials in this region should come from the deep interior of the Earth. With the multi-stage evolution of mantle plume,ore-forming fluids in the deep interior were moving upwards to shallow levels (crust). Under such circumstances,there would be inevitably occur crust/mantle fluid mixing,so their noble gas isotopic characteristics are intermediate between the mantle and the crust.

  1. Timing of multiple hydrothermal events in the iron oxide-copper-gold deposits of the Southern Copper Belt, Carajás Province, Brazil

    Science.gov (United States)

    Moreto, Carolina P. N.; Monteiro, Lena V. S.; Xavier, Roberto P.; Creaser, Robert A.; DuFrane, S. Andrew; Melo, Gustavo H. C.; Delinardo da Silva, Marco A.; Tassinari, Colombo C. G.; Sato, Kei

    2015-06-01

    The Southern Copper Belt, Carajás Province, Brazil, hosts several iron oxide-copper-gold (IOCG) deposits, including Sossego, Cristalino, Alvo 118, Bacuri, Bacaba, Castanha, and Visconde. Mapping and U-Pb sensitive high-resolution ion microprobe (SHRIMP) IIe zircon geochronology allowed the characterization of the host rocks, situated within regional WNW-ESE shear zones. They encompass Mesoarchean (3.08-2.85 Ga) TTG orthogneiss, granites, and remains of greenstone belts, Neoarchean (ca. 2.74 Ga) granite, shallow-emplaced porphyries, and granophyric granite coeval with gabbro, and Paleoproterozoic (1.88 Ga) porphyry dykes. Extensive hydrothermal zones include albite-scapolite, biotite-scapolite-tourmaline-magnetite alteration, and proximal potassium feldspar, chlorite-epidote and chalcopyrite formation. U-Pb laser ablation multicollector inductively coupled mass spectrometry (LA-MC-ICP-MS) analysis of ore-related monazite and Re-Os NTIMS analysis of molybdenite suggest multiple Neoarchean (2.76 and 2.72-2.68 Ga) and Paleoproterozoic (2.06 Ga) hydrothermal events at the Bacaba and Bacuri deposits. These results, combined with available geochronological data from the literature, indicate recurrence of hydrothermal systems in the Southern Copper Belt, including 1.90-1.88-Ga ore formation in the Sossego-Curral ore bodies and the Alvo 118 deposit. Although early hydrothermal evolution at 2.76 Ga points to fluid migration coeval with the Carajás Basin formation, the main episode of IOCG genesis (2.72-2.68 Ga) is related to basin inversion coupled with Neoarchean (ca. 2.7 Ga) felsic magmatism. The data suggest that the IOCG deposits in the Southern Copper Belt and those in the Northern Copper Belt (2.57-Ga Salobo and Igarapé Bahia-Alemão deposits) do not share a common metallogenic evolution. Therefore, the association of all IOCG deposits of the Carajás Province with a single extensive hydrothermal system is precluded.

  2. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070291 Gong Ping (Northern Fujian Geological Party, Shaozou 354000) Discussion on Geological Characteristics and Control Factors of the Shimen Au-polymetallic Deposit in Zhenghe County, Fujian Province (Geology of Fujian, ISSN1001-3970, CN38-1080/P, 25(1), 2006, p.18-24, 2 illus., 2 tables, 1 ref.) Key words: gold deposits, polymetallic deposits, Fujian Province

  3. Site-specific deposition of single gold nanoparticles by individual growth in electrohydrodynamically-printed attoliter droplet reactors

    Science.gov (United States)

    Schneider, Julian; Rohner, Patrik; Galliker, Patrick; Raja, Shyamprasad N.; Pan, Ying; Tiwari, Manish K.; Poulikakos, Dimos

    2015-05-01

    Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma ashing. With this non-contact technique, single particles with diameters tunable in the range of 5-35 nm and with narrow size distribution, high yield and alignment accuracy are generated on demand and patterned into arbitrary arrays. The nanoparticles feature good catalytic activity as shown by the exemplary growth of silicon nanowires from the nanoparticles and the etching of nanoholes by the printed nanoparticles.Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma

  4. Highly active thermally stable nanoporous gold catalyst

    Science.gov (United States)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  5. Highly active thermally stable nanoporous gold catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  6. Visible light activity of pulsed layer deposited BiVO{sub 4}/MnO{sub 2} films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation

    Energy Technology Data Exchange (ETDEWEB)

    Trzciński, Konrad, E-mail: trzcinskikonrad@gmail.com [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Szkoda, Mariusz [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Sawczak, Mirosław [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid Flow Machinery, Fiszera 14, 80-231 Gdansk (Poland); Karczewski, Jakub [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Lisowska-Oleksiak, Anna [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland)

    2016-11-01

    Highlights: • The BiVO{sub 4} + MnO{sub 2} photoactive layers were prepared by pulsed laser deposition method. • Prepared layers can act as photoanodes for water splitting. • The thin BiVO{sub 4} + MnO{sub 2} film can be used as photocatalyst for methylene blue degradation. • The formation of hydroxyl radicals during photocatalys illumination has been proved. • The dropcasted GNP improved significantly photocatalytic properties of tested layers. - Abstract: Thin films containing BiVO{sub 4} and MnO{sub 2} deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27–115 nm) were characterized using Raman spectroscopy, UV–vis spectroscopy and scanning electron microscopy. Electrochemical methods such as electrochemical impedance spectroscopy, linear voltammetry and chronoamperometry under visible light illumination and in the dark were applied to characterize layers as photoanodes. Simple modification of the BiVO{sub 4} + MnO{sub 2} layer by drop-casting of small amount of colloidal gold (1.5 × 10{sup −14} mol of GNP on 1 cm{sup 2}) leads to enhancement of the generated photocurrent recorded at E = 0.5 V vs. Ag/AgCl (0.1 M KCl) from 63 μA/cm{sup 2} to 280 μA/cm{sup 2}. Photocatalytical studies were also exploited towards decomposition of methylene blue (MB). A possible mechanism of MB photodegradation was proposed. The formation of hydroxyl radicals was detected by photoluminescence spectra using terephthalic acid as the probe molecule.

  7. Electroless deposition of Gold-Platinum Core@Shell Nanoparticles on Glassy Carbon Electrode for Non-Enzymatic Hydrogen Peroxide sensing#

    Indian Academy of Sciences (India)

    Gowthaman N S K; Abraham John S

    2016-03-01

    A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticlesz (Au@PtNPs) with core@shell structure fabricated on glassy carbon electrode (GCE) by electroless depositionmethod. Initially, gold nanoparticles (AuNPs) were deposited on GCE by reducing HAuCl4 in the presence of NH2OH and the deposited AuNPs on GCE act as the nucleation centre for the deposition of platinum nanoparticles (PtNPs) in the presence of H2PtCl6 and NH2OH. SEM and AFM studies demonstrated that the electrolessdeposition of Pt on Au was isotropic and uniform. Further, Au@PtNP-modified substrates were characterizedby X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDAX) and cyclic voltammetry (CV). XPS showed characteristic binding energies at 71.2 and 74.4 eV for PtNPs and, 83.6 and 87.3 eV forAuNPs indicating the zero-valent nature in both of them. The electrocatalytic activity of Au@PtNP-modifiedelectrode was investigated towards hydrogen peroxide (HP) reduction. The modified electrode exhibited higherelectrocatalytic activity towards HP by not only shifting its reduction potential by 370 mV towards less positivepotential but also by enhancing the reduction current when compared to bare and AuNP-modified GCE. Thepresent method shows better sensitivity compared to the reported methods in literature and the detection limitwas found to be 60 nM.

  8. Towards a single step process to create high purity gold structures by electron beam induced deposition at room temperature

    Science.gov (United States)

    Mansilla, C.; Mehendale, S.; Mulders, J. J. L.; Trompenaars, P. H. F.

    2016-10-01

    Highly pure metallic structures can be deposited by electron beam induced deposition and they have many important applications in different fields. The organo-metallic precursor is decomposed and deposited under the electron beam, and typically it is purified with post-irradiation in presence of O2. However, this approach limits the purification to the surface of the deposit. Therefore, ‘in situ’ purification during deposition using simultaneous flows of both O2 and precursor in parallel with two gas injector needles has been tested and verified. To simplify the practical arrangements, a special concentric nozzle has been designed allowing deposition and purification performed together in a single step. With this new device metallic structures with high purity can be obtained more easily, while there is no limit on the height of the structures within a practical time frame. In this work, we summarize the first results obtained for ‘in situ’ Au purification using this concentric nozzle, which is described in more detail, including flow simulations. The operational parameter space is explored in order to optimize the shape as well as the purity of the deposits, which are evaluated through scanning electron microscope and energy dispersive x-ray spectroscopy measurements, respectively. The observed variations are interpreted in relation to other variables, such as the deposition yield. The resistivity of purified lines is also measured, and the influence of additional post treatments as a last purification step is studied.

  9. Investigation of the mechanism of electroless deposition of copper on functionalized alkanethiolate self-assembled monolayers adsorbed on gold.

    Science.gov (United States)

    Lu, Peng; Walker, Amy V

    2007-12-04

    We have investigated the reaction pathways involved in the unseeded electroless deposition of copper on self-assembled monolayers (SAMs) adsorbed on Au, using time-of-flight secondary ion mass spectrometry, optical microscopy, and scanning electron microscopy. At 22 degrees C copper deposits on both -CH3 and -COOH terminated SAMs. No copper deposition is observed on -OH terminated SAMs because the hydroxyl terminal groups react with formaldehyde in the plating solution, forming an acetal which prevents Cu deposition. At higher deposition temperatures (45 degrees C), no Cu is observed to deposit on -CH3 terminated SAMs because Cu2+ ions are not stabilized on the SAM surface. Copper complexes are still able to form with the -COOH terminal group at 45 degrees C, and so copper continues to be deposited on -COOH terminated SAMs. Copper also penetrates through -CH3 and -COOH terminated SAMs to the Au/S interface, suggesting that soft deposition techniques do not prevent the penetration of low-to-moderate reactivity metals through organic films.

  10. Predictive mapping using GIS to locate epithermal gold deposits at Cabo de Gata (Prov. of Almeria, Spain); Cartografia predictiva mediante SIG de depositos epitermales de oro en Cabo de Gata, Almeria, Espana

    Energy Technology Data Exchange (ETDEWEB)

    Rogol-Sanchez, J. P.; Chica-Olmo, M.; Rodriguez-Galiano, V.; Pardo-Iguzquiza, E.

    2011-07-01

    The main aim of mineral potential mapping is to generate predictive maps showing the spatial distribution of a numerical index of favour ability for the presence of a mineral deposit of the type sought. We have studied the mineral favorability for epithermal gold deposits in the Cabo de Gata volcanic field in the Province of Almeria in Spain. Predictive maps deriving from the models suggest the presence of several potentially favourable zones. The performance of predictive maps is similar in most cases. Nevertheless, data-driven methods are able to capture more readily the spatial distribution of known gold occurrences in the area. (Author) 32 refs.

  11. Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

    Science.gov (United States)

    McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

    2016-01-01

    High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three

  12. Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits

    Science.gov (United States)

    Person, M.; Banerjee, A.; Hofstra, A.; Sweetkind, D.; Gao, Y.

    2008-01-01

    The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic fluid source, discharge areas restricted to fault zones, and remarkably high temperatures (>200 ??C) at shallow depths (200-1500 m). While the plumbing of these systems varies, geochemical and isotopic data collected at the Dixie Valley and Beowawe geothermal systems suggest that fluid circulation along fault zones was relatively deep (>5 km) and comprised of relatively unexchanged Pleistocene meteoric water with small (enthalpy, ??18O, silica compositions of fluids and/or rocks, groundwater residence times, fluid inclusion homogenization temperatures, and apatite fission track anomalies. Our results suggest that these hydrothermal systems were driven by natural thermal convection along anisotropic, subvertical faults connected in many cases at depth by permeable aquifers within favorable lithostratigraphic horizons. Those with minimal fluid ?? 18O shifts are restricted to high-permeability fault zones and relatively small-scale (???5 km), single-pass flow systems (e.g., Beowawe). Those with intermediate to large isotopic shifts (e.g., epithermal and Carlin-type Au) had larger-scale (???15 km) loop convection cells with a greater component of flow through marine sedimentary rocks at lower water/rock ratios and greater endowments of gold. Enthalpy calculations constrain the duration of Carlin-type gold systems to probably concentrations suggest that the duration of the modern Beowawe system is enthalpy fluids. Computed fission track ages along the Carlin trend included the convective effects, and ranged between 91.6 and 35.3 Ma. Older fission track ages occurred in zones of

  13. 西藏雄村铜金矿床经济评价%Economic Evaluation of Xiongcun Copper-gold Deposit in Tibet

    Institute of Scientific and Technical Information of China (English)

    李丕蓉; 李志军; 郎兴海

    2014-01-01

    西藏雄村铜金矿是最近在西藏日喀则地区发现的一个超大型矿床在对矿床地质特征、经济技术条件进行分析的基础上,采用静态和动态评价方法对矿床经济价值进行评价,通过投资利润率、投资收益率、投资回收期等经济技术指标开展盈亏分析,选取处理成本、铜价作为不确定因素进行了单变量敏感性分析,同时在保证边界品位的基础上以处理成本和回收率作为不确定因素进行了双变量敏感性分析,认为该矿床具有较高的经济价值,矿山生产建设的条件在经济上是可行的。%Xiongcun copper-gold deposit is a super-large deposit recently discovered in Shigatse District,Tibet.On the basis of analyzing the geological characteristics and the economic and technical conditions and evaluating the economic value of the deposit with static and dynamic evaluation method,this paper analyzes the gain and loss in terms of profit ratio of investment, rate of return on investment and investment payoff period.Then a univariate sensitivity analysis is done selecting such factors as the treatment cost and copper price and a bivariate sensitivity analysis is done with the treatment cost and the rate of recovery.The results indicate that Xiongcun copper-gold deposit has a relatively high economic value and that the conditions of productive construction of the deposit are economically feasible.

  14. Metallogenic belt and mineral deposit maps of northeast Asia

    Science.gov (United States)

    Obolenskiy, Alexander A.; Rodionov, Sergey M.; Dejidmaa, Gunchin; Gerel, Ochir; Hwang, Duk-Hwan; Miller, Robert J.; Nokleberg, Warren J.; Ogasawara, Masatsugu; Smelov, Alexander P.; Yan, Hongquan; Seminskiy, Zhan V.

    2013-01-01

    This report contains explanatory material and summary tables for lode mineral deposits and placer districts (Map A, sheet 1) and metallogenic belts of Northeast Asia (Maps B, C, and D on sheets 2, 3, and 4, respectively). The map region includes eastern Siberia, southeastern Russia, Mongolia, northeast China, and Japan. A large group of geologists—members of the joint international project, Major Mineral Deposits, Metallogenesis, and Tectonics of Northeast Asia—prepared the maps, tables, and introductory text. This is a cooperative project with the Russian Academy of Sciences, Mongolian Academy of Sciences, Mongolian National University, Ulaanbaatar, Mongolian Technical University, Mineral Resources Authority of Mongolia, Geological Research Institute, Jilin University, China Geological Survey, Korea Institute of Geoscience and Mineral Resources, Geological Survey of Japan, and U.S. Geological Survey. This report is one of a series of reports on the mineral resources, geodynamics, and metallogenesis of Northeast Asia. Companion studies include (1) a detailed geodynamics map of Northeast Asia (Parfenov and others, 2003); (2) a compilation of major mineral deposit models (Rodionov and Nokleberg, 2000; Rodionov and others, 2000); (3) a series of metallogenic belt maps (Obolenskiy and others, 2004); (4) location map of lode mineral deposits and placer districts of Northeast Asia (Ariunbileg and others, 2003b); (5) descriptions of metallogenic belts (Rodionov and others, 2004); (6) a database on significant metalliferous and selected nonmetalliferous lode deposits and selected placer districts (Ariunbileg and others, 2003a); and (7) a series of summary project publications (Ariunbileg and 74 others, 2003b).

  15. Optical Properties of β-RDX Thin Films Deposited on Gold and Stainless Steel Substrates Calculated from Reflection-Absorption Infrared Spectra.

    Science.gov (United States)

    Ruiz-Caballero, José L; Aparicio-Bolaño, Joaquín A; Figueroa-Navedo, Amanda M; Pacheco-Londoño, Leonardo C; Hernandez-Rivera, Samuel P

    2017-08-01

    The optical properties for crystalline films of the highly energetic material (HEM) hexahydro-1,3,5-trinitro-s-triazine, which is also known as RDX, deposited on gold (Au) and stainless steel (SS) substrates are presented. RDX has two important stable conformational polymorphs at room temperature: α-RDX and β-RDX. The optical properties obtained in the present work correspond to thin film samples of predominantly β-RDX polymorph. The infrared spectroscopic intensities measured showed significant differences in the β-RDX crystalline films deposited on the two substrates with respect to the calculated real part of refractive index. The β-RDX/Au crystalline films have a high dynamic response, which is characterized by the asymmetric stretching mode of the axial nitro groups, whereas for the β-RDX/SS crystalline films, the dynamic response was mediated by the -N-NO2 symmetric stretch mode. This result provides an idea of how the electric field vector propagates through the β-RDX crystalline films deposited on the two substrates.

  16. Single grain Rb-Sr dating of euhedral and cataclastic pyrite from the Qiyugou gold deposit in western Henan,central China

    Institute of Scientific and Technical Information of China (English)

    HAN YiGui; LI XiangHui; ZHANG ShiHong; ZHANG YuanHou; CHEN FuKun

    2007-01-01

    The Rb-Sr isotopic dating of pyrite mineral from ore deposits can directly provide mineralization age. However,many geological factors may affect the Rb-Sr isotopic system,which baffles application of this method. Employing ultra-low procedural blank Rb-Sr method,we have dated pyrites separated from the No. 4 breccia pipe of the Qiyugou gold deposit,western Henan Province. Single grains of euhedral pyrite crystal with few micro-cracks yield an isochron age of 126 ± 11 Ma,which represents time of the main mineralization stage of the deposit. Pyrite grains of cataclastic type show nevertheless scattered Rb-Sr isotopic composition and no reasonable isochron can be defined. Crystal morphology and mineral inclusion studies reveal that Rb and Sr of pyrite mineral probably are preserved mainly in biotite,K-feldspar,and sericite mineral inclusions. The dating results likely suggest that cataclastic pyrite is not suitable for the Rb-Sr dating due to modification of the Rb-Sr isotopic system by later hydrothermal activity of fluid.

  17. 福建德化石头坂金矿地质特征及找矿标志%Geologic characteristics and prospecting criteria of the Shitouban gold deposit in Dehua County,Fujian Province

    Institute of Scientific and Technical Information of China (English)

    李兴城

    2015-01-01

    The Shitouban gold deposit is located in the western of east Fujian fracture depression and it's an important discovery of prospecting work. By analyzing the geological characteristics of the deposit, it is re-vealed that the gold deposit is a medium low temperature hydrothermal ore deposit after the magma period. The prospecting criteria are concluded as well.%石头坂金矿位于闽东火山断拗带的西部,是该成矿区带发现的重要金矿床。通过对石头坂金矿床地质特征的分析研究,认为其矿床成因类型属岩浆期后中低温热液矿床,并系统总结了找矿标志。

  18. Pb isotope geochemistry of lead, zinc, gold and silver deposit clustered region, Liaodong rift zone,northeastern China

    Institute of Scientific and Technical Information of China (English)

    CHEN; Jiangfeng; YU; Gang; XUE; Chunji; QIAN; Hui; HE; Jian

    2005-01-01

    33 Pb isotopic analyses were reported for sulfide and hydrothermal carbonate minerals and marble of the Xiquegou lead-zinc, the Zhenzigou zinc-lead and the Gaojiapuzi silver deposits from the Qingchengzi ore field and the Beiwagou zinc-lead deposit in the west, Proterozoic Liaodong rift zone. Pb isotopic ratios of the marble from the Qingchengzi ore field range from 18.24 to 30.63 for 206Pb/204Pb, 15.59 to 17.05 for 207Pb/204Pb and 37.43 to 38.63 for 208Pb/204Pb. The marble gives a Pb-Pb isochron age of 1822±92 Ma, which is interpreted as the age of the metamorphism of the marble. Ore Pb, including Pb of sulfide and hydrothermal carbonate minerals, from the Qingchengzi ore field shows limited variation with 206Pb/204Pb=17.66-17.96, 207Pb/204Pb=15.60-15.74 and 208Pb/204Pb=37.94-38.60. In contrast, ore Pb from the Beiwagou deposit gives different Pb isotopic ratios with 206Pb/204Pb=15.68-15.81, 207Pb/204Pb= 15.34-15.45 and 208Pb/204Pb=35.30-35.68. Pb of all deposits from the Liaodong rift zone is derived from the upper crust. Ore Pb of the Qingchengzi deposits is derived from a young upper crust. The model Th/U ratios of 4.40 to 4.74 for ore Pb are significantly different from that of 1.7 to 4.4 given by the marble of the Qingchengzi ore field, suggesting that marble is not the source of the ore Pb. Ore Pb of the Beiwagou deposit is extracted from its source and the deposit is formed at the Paleoproterozoic era. Different Pb isotopic ratios of the Qingchengzi ore field and the Beiwagou deposit are due to different ages of the deposits and suggest that the two types of deposits are derived from different sources and are possibly formed by different ore-forming processes.

  19. S, C, O, H Isotope Data and Noble Gas Studies of the Maoniuping LREE Deposit, Sichuan Province, China: A Mantle Connection for Mineralization

    Institute of Scientific and Technical Information of China (English)

    TIAN Shihong; DING Tiping; MAO Jingwen; LI Yanhe; YUAN Zhongxin

    2006-01-01

    The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Autonomous Region. Tectonically, it is located in the transitional zone between the Panxi rift and the Longmenshan-Jinpingshan orogenic zone. It is a carbonatite vein-type deposit hosted in alkaline complex rocks. The bastnaesite-barite, bastnaesite-calcite, and bastnaesitemicrocline lodes are the main three types of REE ore lodes. Among these, the first lode is distributed most extensively and its REE mineralization is the strongest. The δ34SV-CDT values of the barites in the ore of the deposit vary in a narrow range of +5.0 to +5.1‰ in the bastnaesite-calcite lode and +3.3 to +5.9‰ in the bastnaesite-barite lode, showing the isotopic characteristics of magma-derived sulfur. The δ13CV-PDB values and the δ18OV-SMOW values in the bastnaesite-calcite lode range from -3.9 to -6.9‰ and from +7.3 to +9.7 ‰, respectively, which fall into the range of "primary carbonatites", showing that carbon and oxygen in the ores of the Maoniuping deposit were derived mainly from a deep source. The δ13CV-PDB values of fluid inclusions vary from -3.0 to -5.6‰, with -3.0 to -4.0‰ in the bastnaesitecalcite lode and -3.0 to -5.6‰ in the bastnaesite-barite lode, which show characteristics of mantlederived carbon. The δDv-SMOW values of fluid inclusions range from -57 to -88‰, with -63 to -86‰ in the bastnaesite-calcite lode and -57 to -88‰ in the bastnaesite-barite lode, which show characteristics of mantle-derived hydrogen. The δ18OH2OV-SMOW values vary from +7.4 to +8.6‰ in the bastnaesitecalcite lode, and +6.7 to +7.8‰ in the bastnaesite-barite lode, almost overlapping the range of +5.5 to +9.5‰ for magmatic water. The 4He content, R/Ra ratios are (13.95 to 119.58)×10-6 (cm3/g)STP and 0.02 to 0.11, respectively, and 40Ar/36Ar is 313 ± 1 to 437

  20. THE GEOLOGICAL CONDITIONS OF FORMATION AND MINERALIZATION FEATURES OF MICRO-FINE DISSEMINATED GOLD DEPOSITS IN CHINA%我国微细浸染型金矿床的形成条件及成矿作用特征

    Institute of Scientific and Technical Information of China (English)

    王可勇

    2000-01-01

    微细浸染型金矿床是我国主要的热液金矿床类型之一,空间上多分布于扬子地台周边地区,其产出受大地构造背景及地层、构造和一定的热动力条件的控制.我国该类型金矿床成矿作用总体具有如下特点:①矿化点多面广,但规模相对较小;②区域上金矿化常与Hg、Sb、As及U等元素低温热液矿床密切共(伴)生;③矿床形成具多期多阶段性,且其成因复杂多样;④成矿时代主要为印支晚期-燕山期.%Micro-fine disseminated gold deposit is one of the most important hydrothermal deposit types in Cb ina. Most of th em are spatially distributed iu regions around the Yangtze platform, and their occurences are controlled by strata, structure and certain thermodynamic conditions in addition to tectonic backgrounds. The mineralization features of this type of gold deposits are as follows: (①) gold mineralization is distributed extensively in space, but the deposits are usually smaller in scale relatively; (②)regionally, gold mineralization often occurred in accompanion with low temperature hydrothermal deposits of Sb, As, Hg, U etc.; (③)the formation of the gold deposits experienced multiphases as well as polystages of mineralizing processes, and their origins are usually different and complex;and (④)the main metallogenic period is from late Indo-Chinese epoch to Yanshanian epoch.

  1. Photocurrent enhancement by surface plasmon resonance of gold nanoparticles in spray deposited large area dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chander, Nikhil; Singh, Puneet [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Khan, A.F. [Department of Electronics and Information Technology, Ministry of Communications and Information Technology, Government of India, New Delhi 110003 (India); Dutta, Viresh [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Komarala, Vamsi K., E-mail: vamsi@ces.iitd.ac.in [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2014-10-01

    A facile method for fabricating large area TiO{sub 2} and TiO{sub 2}–Au nanocomposite films for dye sensitized solar cells (DSSCs) is presented using a spray technique. Pre-synthesized gold nanoparticles (Au NPs) were sprayed together with the TiO{sub 2} NPs and composite films with brilliant coloration due to surface plasmon resonances of Au NPs were prepared. Composite films containing ∼ 15 nm sized Au NPs exhibited enhanced absorption in the visible region of the electromagnetic spectrum. DSSCs with a large area of ∼ 4.5 cm{sup 2} were fabricated and a photocurrent enhancement of ∼ 10% was obtained for plasmonic DSSC containing 0.3 wt.% of ∼ 15 nm Au NPs. Incident photon to current conversion efficiency data conclusively showed enhanced currents in the visible region of the polychromatic spectrum arising due to plasmon enhanced near-field effects of Au NPs around the absorbing dye molecules. - Highlights: • Preparation of TiO{sub 2} and TiO{sub 2}–Au films with a large area of ∼ 7.5 cm{sup 2} by a spray technique • An efficiency of ∼ 4.5% achieved by the large area plasmonic DSSC • Photocurrent enhancement due to SPR effects of gold NPs observed • Comparison of the spray and conventional doctor blade methods in DSSC performance • Demonstration of technological feasibility and versatility of a simple spray process.

  2. Regional framework and geology of iron oxide-apatite-rare earth element and iron oxide-copper-gold deposits of the Mesoproterozoic St. Francois Mountains Terrane, southeast Missouri

    Science.gov (United States)

    Day, Warren C.; Slack, John F.; Ayuso, Robert A.; Seeger, Cheryl M.

    2016-01-01

    This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite province. The province formed during two major pulses of igneous activity: (1) an older early Mesoproterozoic (ca. 1.50–1.44 Ga) episode of volcanism and granite plutonism, and (2) a younger middle Mesoproterozoic (ca. 1.33–1.30 Ga) episode of bimodal gabbro and granite plutonism. The volcanic rocks are predominantly high-silica rhyolite pyroclastic flows, volcanogenic breccias, and associated volcanogenic sediments with lesser amounts of basaltic to andesitic volcanic and associated subvolcanic intrusive rocks. The iron oxide deposits are all hosted in the early Mesoproterozoic volcanic and volcaniclastic sequences. Previous studies have characterized the St. Francois Mountains terrane as a classic, A-type within-plate granitic terrane. However, our new whole-rock geochemical data indicate that the felsic volcanic rocks are effusive derivatives from multicomponent source types, having compositional similarities to A-type within-plate granites as well as to S- and I-type granites generated in an arc setting. In addition, the volcanic-hosted IOA and IOCG deposits occur within bimodal volcanic sequences, some of which have volcanic arc geochemical affinities, suggesting an extensional tectonic setting during volcanism prior to emplacement of the ore-forming systems.The Missouri iron orebodies are magmatic-related hydrothermal deposits that, when considered in aggregate, display a vertical zonation from high-temperature, magmatic ± hydrothermal IOA deposits emplaced at moderate depths (~1–2 km), to magnetite-dominant IOA veins and IOCG deposits emplaced at shallow

  3. Surface preparation of gold nanostructures on glass by ultraviolet ozone and oxygen plasma for thermal atomic layer deposition of Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lancaster, Cady A., E-mail: lancaster@chem.utah.edu; Shumaker-Parry, Jennifer S., E-mail: shumaker-parry@chem.utah.edu

    2016-08-01

    Thin film deposition to create robust plasmonic nanomaterials is a growing area of research. Plasmonic nanomaterials have tunable optical properties and can be used as substrates for surface-enhanced spectroscopies. Due to the surface sensitivity and the dependence of the near-field behavior on structural details, degradation from cleaning or spectroscopic interrogation causes plasmonic nanostructures to lose distinctive localized surface plasmon resonances or exhibit diminished optical near-field enhancements over time. To decrease degradation, conformal thin films of alumina are deposited on nanostructured substrates using atomic layer deposition. While film growth on homogenous surfaces has been studied extensively, atomic layer deposition-based film growth on heterogeneous nanostructured surfaces is not well characterized. In this report, we have evaluated the impact of oxygen plasma and ultraviolet ozone pre-treatments on Au nanoparticle substrates for thin film growth by monitoring changes in plasmonic response and nanostructure morphology. We have found that ultraviolet ozone is more effective than oxygen plasma for cleaning gold nanostructured surfaces, which is in contrast to bulk films of the same material. Our results show that oxygen plasma treatment negatively impacts the nanostructure and alumina coating based on both scanning electron microscopy analysis of morphology and changes in the plasmonic response. - Highlights: • Plasmonic response indicates oxygen plasma damages Au structures and Al{sub 2}O{sub 3} films. • Ultraviolet ozone (UVO) re-activates aged Al{sub 2}O{sub 3}-coated Au nanostructures. • UVO treatments do not damage Au or Al{sub 2}O{sub 3}-coated nanostructures.

  4. Experimental study on extracting gold and silver from depositing-sludge%从某沉积污泥中提取金、银试验研究

    Institute of Scientific and Technical Information of China (English)

    简椿林

    2013-01-01

    采用焙烧-酸浸-氰化工艺从沉积污泥中提取金、银,试验考察了氰化浸出反应液固比、pH值、氰化钠质量分数、反应时间、搅拌速度对金、银浸出率的影响。沉淀污泥在焙烧温度903 K、焙烧时间2 h的条件下,进行预处理;焙砂在反应液固比4∶1、硫酸浓度0.5 mol/L、反应时间3 h、反应温度323 K、搅拌速度300 r/min的条件下,进行硫酸浸出;酸浸渣在反应液固比4∶1、pH 10.5、氰化钠质量分数0.4%、反应温度298 K、搅拌速度250 r/min、反应时间72 h的条件下,进行氰化浸出;金、银浸出率分别可达93.2%、79.1%。%Roasting-acid leaching-cyanide process was used to extract gold and silver from depositing-sludge.The effects of liquid-solid ratio,pH value,NaCN concentration,reaction temperature,stirring speed on extraction rate of gold and silver were investigated.Pre-treatment of depositing-sludge is done with the roasting temperature of 903 K and roasting time of 2 h.The sulfuric acid leaching of calcine goes under the conditions such as liquid-solid ratio of 4∶1, H2 SO4 concentration of 0.5 mol/L, reaction temperature of 323 K, reaction time of 3 h and stirring speed of 300 r/min.The cyanide leaching condition is like this:liquid-solid ration of 4∶1,pH value of 10.5,NaCN concentra-tion of 0.4 %,stirring speed of 300 r/min and reaction time of 72 h.Under such conditions,the extraction rates of gold and silver were respectively 93.20 %and 79.10 %.

  5. A Research of Ore-Forming Conditions of Nipu Gold Deposit in Guizhou Province, China%贵州泥堡金矿床成矿地质条件研究

    Institute of Scientific and Technical Information of China (English)

    孙军; 聂爱国; 黄思涵; 付斌; 陈世委

    2012-01-01

    The Nipu gold deposit is one of the important components of Carlin-type gold mining area, which is located in Southwest of Cuizhou Province. However, Nipu has its remarkable characteristics in host rocks, gold bearing formation and lithofacies palaeogeography. By researching the forming conditions of Nipu gold deposit, it is found that the mater and heat sources of Nibao gold deposit come from the Emei mantle plume's activities whichis the prerequisites of forming and activating the Ore-bearing hydrothermal. Also the location and formation of Nibao gold deposit are ultimately determined by a large scale of orogenic movements in Yanshanian period.%泥堡金矿是黔西南卡林型金矿矿集区的重要组成部分,但在赋矿岩石、含金建造和岩相古地理位置方面,泥堡金矿具有显著的特殊性.本文通过对贵州泥堡金矿床成矿地质条件的研究,分析认为峨眉山地幔热柱的活动为泥堡金矿的形成提供了物质来源和热能来源,为含矿热液的形成和活动创造了前提条件,燕山期大规模的构造造山运动最终决定了泥堡金矿的定位和形成.

  6. Geochemical characteristics of Huanggou gold deposit in western Henan%豫西黄沟金矿床地质地球化学特征

    Institute of Scientific and Technical Information of China (English)

    王秀全

    2015-01-01

    This paper studied geochemical characteristics of Huanggou gold deposit and elaborated on the effect of Taihua formation on mineralization of gold deposits in this area.The result suggested that(1 )the protolith of gneiss was igneous and fell in high-k calc-alkaline series,and gold ores were pervasively charac-terized by Na-poorness and K-Ca-richness and high grade of SiO 2 content,while the grade of Au was positive-ly correlated to content of SiO 2 ;(2)the trace element characteristics suggested sever edepletion of elements like Rb,Ta,Ti,Ba,Sm and Y in the ore samples,and the similar normalized pattern with gneiss of Taihua Group and andesite of Xiong'er Group suggested that Au mineralization was possibly associated with gneiss and andesite in terms of genesis;(3)the rare earth element characteristics suggested slight depletion of light rare earth and slight enrichment of heavy rare earth in most of the gold ores.Weak negative Eu anomaly was quite different from the normalized pattern of various out cropped rocks and rare earth elements in this area (right declined),yet was derived from deep part.The normalized pattern of some gold ore was to some ex-tent similar with gneiss or (and)andesite and had the right declined weak negative Eu anomaly pattern,and it suggested that the genesis of Taihua Group and (or)andesite of Xiong’er Group contributed some ore-form-ing substances to the mineralization.%通过研究黄沟金矿床中岩石地球化学特征,从而探讨太华群地层对于该区金矿床成矿的作用。研究表明(1)本区的片麻岩原岩主要为火成岩,属高钾钙碱性系列,且金矿石一般都明显贫钠而富钾、富钙,SiO 2含量普遍较高,Au 品位随 SiO 2的含量增高而呈正相关变化;(2)微量元素特征表明矿石样品以Rb、Ta、Ti 等元素强烈亏损,Ba、Sm 和 Y 元素强烈亏损为特征,与太华群片麻岩和熊耳群安山岩的标准化分布曲线型式接近,说明金矿化可能与太华群片麻

  7. The geology, structure and mineralisation of the Oyu Tolgoi porphyry copper-gold-molybdenum deposits, Mongolia:A review

    Institute of Scientific and Technical Information of China (English)

    T.M. Mike Porter

    2016-01-01

    The Oyu Tolgoi cluster of seven porphyry Cu-Au-Mo deposits in southern Mongolia, define a narrow, linear, 12 km long, almost continuously mineralised trend, which contains in excess of 42 Mt of Cu and 1850 t of Au, and is among the largest high grade porphyry Cu-Au deposits in the world. These deposits lie within the Gurvansayhan island-arc terrane, a fault bounded segment of the broader Silurian to Carboniferous Kazakh-Mongol arc, located towards the southern margin of the Central Asian Orogenic Belt, a collage of magmatic arcs that were periodically active from the late Neoproterozoic to Permo-Triassic, extending from the Urals Mountains to the Pacific Ocean. Mineralisation at Oyu Tolgoi is associated with multiple, overlapping, intrusions of late Devonian (w372 to 370 Ma) quartz-monzodiorite intruding Devonian (or older) juvenile, probably intra-oceanic arc-related, basaltic lavas and lesser volcaniclastic rocks, unconformably overlain by late Devonian (w370 Ma) basaltic to dacitic pyroclastic and volcano sedimentary rocks. These quartz-monzodiorite intrusions range from early-mineral porphyritic dykes, to larger, linear, syn-, late- and post-mineral dykes and stocks. Ore was deposited within syn-mineral quartz-monzodiorites, but is dominantly hosted by augite basalts and to a lesser degree by overlying dacitic pyroclastic rocks. Following ore deposition, an allochthonous plate of older Devonian (or pre-Devonian) rocks was overthrust and a post-ore biotite granodiorite intruded at w365 Ma. Mineralisation is characterised by varying, telescoped stages of intrusion and alteration. Early A-type quartz veined dykes were followed by Cu-Au mineralisation associated with potassic alteration, mainly K-feldspar in quartz-monzodiorite and biotite-magnetite in basaltic hosts. Downward reflux of cooled, late-magmatic hydrothermal fluid resulted in intense quartz-sericite retrograde alteration in the upper parts of the main syn-mineral intrusions, and an equivalent chlorite

  8. Tectonic setting of the pebble and other copper-gold-molybdenum porphyry deposits within the evolving middle cretaceous continental margin of Northwestern North America

    Science.gov (United States)

    Goldfarb, Richard J.; Anderson, Eric; Hart, Craig J.

    2013-01-01

    The Pebble Cu-Au-Mo deposit in southwestern Alaska, containing the largest gold resource of any known porphyry in the world, developed in a tectonic setting significantly different from that of the present-day. It is one of a series of metalliferous middle Cretaceous porphyritic granodiorite, quartz monzonite, and diorite bodies, evolved from lower crust and metasomatized lithospheric mantle melts, which formed along much of the length of the North American craton suture with the Peninsular-Alexander-Wrangellia arc. The porphyry deposits were emplaced within the northernmost two of a series of ca. 130 to 80 Ma flysch basins that define the suture, as well as into arc rocks immediately seaward of the two basins. Deposits include the ca. 100 to 90 Ma Pebble, Neacola, and other porphyry prospects along the Kahiltna basin-Peninsula terrane boundary, and the ca. 115 to 105 Ma Baultoff, Carl Creek, Horsfeld, Orange Hill, Bond Creek, and Chisna porphyries along the Nutzotin basin-Wrangellia terrane boundary.The porphyry deposits probably formed along the craton margin more than 1,000 km to the south of their present latitude. Palinspastic reconstructions of plate kinematics from this period are particularly difficult because magmatism overlaps the 119 to 83 Ma Cretaceous Normal Superchron, a period when sea-floor magnetic data are lacking. Our favored scenario is that ore formation broadly overlaps the cessation of sedimentation and contraction and the transition to a transpressional continental margin regime, such that the remnant ocean basins were converted to strike-slip basins. The basins and outboard Peninsular-Alexander-Wrangellia composite superterrane, which are all located seaward of the deep crustal Denali-Farewell fault system, were subjected to northerly dextral transpression for as long as perhaps 50 m.y., beginning at ca. 95 ± 10 Ma. The onset of this transpression was marked by development of the mineralized bodies along fault segments on the seaward side

  9. Formation of charge-nanopatterned templates with flexible geometry via layer by layer deposition of polyelectrolytes for directed self-assembly of gold nanoparticles

    Science.gov (United States)

    Sayin, Mustafa; Dahint, Reiner

    2017-03-01

    Nanostructure formation via self-assembly processes offers a fast and cost-effective approach to generate surface patterns on large lateral scale. In particular, if the high precision of lithographic techniques is not required, a situation typical of many biotechnological and biomedical applications, it may be considered as the method of choice as it does not require any sophisticated instrumentation. However, in many cases the variety and complexity of the surface structures accessible with a single self-assembly based technique is limited. Here, we report on a new approach which combines two different self-assembly strategies, colloidal lithography and layer-by-layer deposition of polyelectrolytes, in order to significantly expand the spectrum of accessible patterns. In particular, flat and donut-like charge-patterned templates have been generated, which facilitate subsequent deposition of gold nanoparticles in dot, grid, ring, out-of-ring and circular patch structures. Potential applications are e.g. in the fields of biofunctional interfaces with well-defined lateral dimensions, optical devices with tuned properties, and controlled three-dimensional material growth.

  10. 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

    Science.gov (United States)

    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

  11. The geology, structure and mineralisation of the Oyu Tolgoi porphyry copper-gold-molybdenum deposits, Mongolia: A review

    Directory of Open Access Journals (Sweden)

    T.M. (Mike Porter

    2016-05-01

    Mineralisation is characterised by varying, telescoped stages of intrusion and alteration. Early A-type quartz veined dykes were followed by Cu-Au mineralisation associated with potassic alteration, mainly K-feldspar in quartz-monzodiorite and biotite-magnetite in basaltic hosts. Downward reflux of cooled, late-magmatic hydrothermal fluid resulted in intense quartz-sericite retrograde alteration in the upper parts of the main syn-mineral intrusions, and an equivalent chlorite-muscovite/illite-hematite assemblage in basaltic host rocks. Uplift, facilitated by syn-mineral longitudinal faulting, brought sections of the porphyry deposit to shallower depths, to be overprinted and upgraded by late stage, shallower, advanced argillic alteration and high sulphidation mineralisation. Key controls on the location, size and grade of the deposit cluster include (i a long-lived, narrow faulted corridor; (ii multiple pulses of overlapping intrusion within the same structure; and (iii enclosing reactive, mafic dominated wall rocks, focussing ore.

  12. The Study of the Ore Character of Luoba Gold Deposit Gansu Province%甘肃省徽县洛坝金矿床矿石特征研究

    Institute of Scientific and Technical Information of China (English)

    李国柱

    2011-01-01

    洛坝金矿床矿石工艺类型为贫硫化物全氧化含金矿石类型,矿石中金矿物为自然金及银金矿,有害元素炭品位为>0.1%,金矿物粒度细小,赋存状态以裂隙金为主,次为粒间金、包裹金;载金矿物主要为褐铁矿,粒度粗细不均,大部分粒度较细;通过对矿石质量研究,为选矿试验提供必要参数,并为矿床下步开发提供依据.%The technical types of the ore of the Luoba deposit is the gold ore types of poor sulfide and all oxidation, the gold mineral in the ore is gold and electrum, the content of Carbon as the deleterious element is above 0.1%, The gold mineral's granularity is exiguous, its beigng state is fissures at first, and then is intergranulars and entrainments; the mineral which carrying the gold element is limonite,it's granularity is asymmetrical, but exiguous in a great measure. By studying the ore quality, this article offered the necessary parameter for mill run and offered the gist for the exploitation of the deposit.

  13. Ultrasensitive electroanalysis of low-level free microRNAs in blood by maximum signal amplification of catalytic silver deposition using alkaline phosphatase-incorporated gold nanoclusters.

    Science.gov (United States)

    Si, Yanmei; Sun, Zongzhao; Zhang, Ning; Qi, Wei; Li, Shuying; Chen, Lijun; Wang, Hua

    2014-10-21

    An ultrasensitive sandwich-type analysis method has been initially developed for probing low-level free microRNAs (miRNAs) in blood by a maximal signal amplification protocol of catalytic silver deposition. Gold nanoclusters (AuNCs) were first synthesized and in-site incorporated into alkaline phosphatase (ALP) to form the ALP-AuNCs. Unexpectedly, the so incorporated AuNCs could dramatically enhance the catalysis activities of ALP-AuNCs versus native ALP. A sandwiched hybridization protocol was then proposed using ALP-AuNCs as the catalytic labels of the DNA detection probes for targeting miRNAs that were magnetically caught from blood samples by DNA capture probes, followed by the catalytic ligation of two DNA probes complementary to the targets. Herein, the ALP-AuNC labels could act as the bicatalysts separately in the ALP-catalyzed substrate dephosphorylation reaction and the AuNCs-accelerated silver deposition reaction. The signal amplification of ALP-AuNCs-catalyzed silver deposition was thereby maximized to be measured by the electrochemical outputs. The developed electroanalysis strategy could allow for the ultrasensitive detection of free miRNAs in blood with the detection limit as low as 21.5 aM, including the accurate identification of single-base mutant levels in miRNAs. Such a sandwich-type analysis method may circumvent the bottlenecks of the current detection techniques in probing short-chain miRNAs. It would be tailored as an ultrasensitive detection candidate for low-level free miRNAs in blood toward the diagnosis of cancer and the warning or monitoring of cancer metastasis in the clinical laboratory.

  14. Microstructural analysis of a subhorizontal gold-quartz vein deposit at Donalda, Abitibi greenstone belt, Canada: Implications for hydrodynamic regime and fluid-structural relationship

    Directory of Open Access Journals (Sweden)

    Guoxiang Chi

    2011-10-01

    Full Text Available The Donalda gold deposit in the southern part of the Archean Abitibi greenstone belt consists mainly of a subhorizontal gold-quartz vein perpendicular to subvertical shear zones. The 0.3–0.5 m thick vein is characterized by vein-parallel banding structures indicating multiple episodes of fracture opening and mineral precipitation. Measurement of the c-axis of primary growth quartz indicates that quartz preferentially grew perpendicular to the fracture, suggesting open space filling and/or extensional nature of the fracture. Measurement of the orientations of microfractures, veinlets and fluid–inclusion planes (FIPs crosscutting primary growth quartz indicates that the vein minerals were subject to a vertical maximum principal stress (σ1, which is inconsistent with the subhorizontal σ1 inferred from the regional stress field with N–S shortening. This apparent discrepancy is explained by invoking episodic fluid pressure fluctuation between supralithostatic and hydrostatic regimes accompanied by episodic opening and closing of the subhorizontal fracture. When fluid pressure was higher than the lithostatic value, the fracture was opened and primary growth minerals were precipitated, whereas when fluid pressure decreased toward the hydrostatic value, the hanging wall of the fracture collapsed, causing collision of protruding primary growth minerals from both sides of the fracture and resulting in formation of vein-parallel deformation bands. The columns where the two facing sides of the fracture collided were subject to higher-than-lithostatic stress due to the bridging effect and reduced support surface area, explaining the development of vertical σ1. This hypothesis is consistent the fault-valve model, and explains the flipping of σ1 without having to change the regional stress field.

  15. 金原子在熔融玻璃表面的凝聚特性%AGGREGATION CHARACTERISTICS OF GOLD ATOMS DEPOSITED ON MOLTEN GLASS SURFACES

    Institute of Scientific and Technical Information of China (English)

    金进生; 钱昌吉; 等

    2001-01-01

    The diffusion,aggregation and crystallization characteristics of gold atoms deposited on molten glass surfaces are studied.Experimental results indicate that the gold atoms first form a characteristic web-shaped Au film on the colloid glass surface,and the average diameter of the crystal grains in the film is about 20 nm.The area of the meshes gradually increases and then the whole film tatters.Thus the compact clusters are formed.The saturated diameter of the compact clusters is about 1.2μm and its diffusion coefficient D is of the order of 107—108 cm2/s.The compact clusters diffuse on the molten glass surface quickly and quasi-randomly,and finally large ramified aggregates with diameter of about 50 μm from.%研究了沉积在熔融玻璃表面的金原子的扩散、凝聚以及结晶行为。实验结果表明:金原子在胶状的玻璃表面先形成具有特征结构的网状薄膜,其中金原子晶粒直径约为20 nm;然后网孔逐渐增大直至薄膜破裂,金原子凝聚成准圆形的团族,其饱和直径约为1.2 μm,扩散系数为10-7—10-8 cm2/s数量级;通过快速且准无规地扩散,准圆形团簇最终凝聚成直径约为50μm的大型分枝状凝聚体。

  16. Geological characteristics and prospecting direction of Zhagela gold deposit in Tibet%西藏扎格拉金矿床地质特征及找矿方向

    Institute of Scientific and Technical Information of China (English)

    张红强; 张红鹏; 安超; 王斌

    2015-01-01

    Zhagela gold deposit of Tibet was located in Bange-Tengchong magmatic arcbelt on the southern limb of Bangonghu-Nujiang conjunctive belt (or Dingqing conjunctive belt).The ore-bodies were strictly controlled by faulted fracture zone in epimetamorphic flysch rock series of Jurassic Xihu Group.The gold mineralization wall rock alteration included silicification,sericitization,pyritization (ferritization),carbon-atization,argillization and chloritization.In respect of geochemistry,anomalies of element associations of Au,As,Sb,W,Mo and Cu occurred and they were effective clues for gold prospecting.This paper compre-hensively summarized the metallogenic and geological characteristics of Zhagela gold deposit,and based on field survey it believed that Zhagela gold deposit was a metamorphic-hydrothermal gold deposit in term of genesis,and was low-sulfide gold ores in term of industry type.The paper also proposed the prospecting di-rection of such type of gold ores in this area.%西藏扎格拉金矿位于班公湖-怒江结合带(简称丁青结合带)南侧的班戈—腾冲岩浆弧带,矿体严格受侏罗统希湖群浅变质复理石岩系中断裂破碎带控制,金矿化围岩蚀变包括有硅化、绢云母化、黄铁矿化(褐铁矿化)、碳酸盐化、粘土化、绿泥石化等。地球化学有 Au、As、Sb、W、Mo、Cu 元素组合的异常,对金矿勘探具有很好的指示作用。全面详细总结了扎格拉金矿成矿地质特征,结合野外地质调查认为扎格拉金矿成因属于变质-热液型金矿床类,工业类型为少硫化物金矿石,同时提出本地区该类型金矿的找矿方向。

  17. Metallogenetic Prediction Based on an Ore-Prospecting Model:An Application of QI Ⅰ Gold Deposit Prospecting Model%基于找矿模型的成矿预测——以齐Ⅰ金矿为例

    Institute of Scientific and Technical Information of China (English)

    曾祥武; 刘家军; 赖月荣; 刘雪刚

    2012-01-01

    安齐成矿带是新疆重要金成矿带,齐Ⅰ金矿是该成矿带目前发现的最大金矿床.对比齐Ⅰ金矿找矿模型,结合遥感解译成果,在周边地区应用地质、物探、化探、遥感等找矿方法进行成矿预测,圈定出多处找矿靶区,经工程验证,发现工业矿体.利用找矿模型以现有资料为基础,以有效勘查方法组合为手段,设计验证工程,指导找矿勘探工作.%The QI I gold deposit is the biggest gold deposit metallogenic belt in anqi,one of the most important gold deposits in XinJiang.In order to enhance geological research and summarize the results of previous survey to guide the later prospecting work,we make comparison with the QI I gold prospecting model and use the remote sensing information to analyze the conditions of mineral formation in this area. Based on QI I ore-prospecting model,we successfully applied a set of effective working methods which integrate geology,geophysics,geochemistry and remote sensing to locate the target ore area quickly around QI I gold deposit. Located some target ore areas,with Au,Ag,As anomaly.Anomaly inspection led to the discovery of the new ore-body,which shows that target selection was fairly successful.On the basis of the prospecting model and comprehensive analysis of the resource potentials scientific resource prospecting plan is put forward and performed,with the ore body in depth being the main exploratory target.

  18. Gold and gold working in Late Bronze Age Northern Greece

    Science.gov (United States)

    Vavelidis, M.; Andreou, S.

    2008-04-01

    Numerous objects of gold displaying an impressive variety of types and manufacturing techniques are known from the Late Bronze Age (LBA) contexts of Mycenaean Greece, but very little is known about the origin and processing of gold during the second millennium b.c. Ancient literature and recent research indicate that northern Greece is probably the richest gold-bearing region in Greece, and yet, very little evidence exists regarding the exploitation of its deposits and the production as well as use of gold in the area during prehistory. The unusual find of a group of small stone crucibles at the prehistoric settlement of Thessaloniki Toumba, one with visible traces of gold melting, proves local production and offers a rare opportunity to examine the process of on-site gold working. Furthermore, the comparison of the chemical composition of prehistoric artefacts from two settlements with those of gold deposits in their immediate areas supports the local extraction of gold and opens up the prospect for some of the Mycenaean gold to have originated in northern Greece. The scarcity of gold items in northern Greek LBA contexts may not represent the actual amount of gold produced and consumed, but could be a result of the local social attitudes towards the circulation and deposition of artefacts from precious metals.

  19. A Comparison of Carlin-type Gold Deposits: Guizhou Province, Golden Triangle, Southwest China, and Northern Nevada, USA%A Comparison of Carlin-type Gold Deposits:Guizhou Province,Golden Triangle,Southwest China,and Northern Nevada,USA

    Institute of Scientific and Technical Information of China (English)

    Jean S.CLINE; John L.MUNTEAN; Xuexiang GU; Yong XIA

    2013-01-01

    Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada,USA,were examined to identify similarities and differences between the two districts.Samples were collected along transects from lowto high-grade rock,where possible,and from stockpiles at the Shuiyindong,Zimudang,Taipingdong,Yata and Jinfeng (formerly Lannigou) deposits.Methods used to examine ore and alteration minerals included hand-sample description; reflectance spectroscopy using an ASD Terraspec spectrometer;analyses of hand samples by carbonate staining with Alizaren red and potassium ferricyanide;transmitted and reflected light petrography; chemical analyses,mineral identification,and imaging using a JEOL JSM-5610 scanning electron microscope; and quantitative chemical analyses using a JEOL JXA-8900 electron probe microanalyzer.Geochemical analyses of hand samples for 52 elements were done by ALS Chemex.Results indicate both similarities and differences between the two districts.Both districts have similar geologic histories,and deposits at both locations appear to have formed as a result of similar tectonic events,though the district in southwest China lacks evidence of coeval felsic igneous activity;however,the ore-stage minerals and the fluids that produced the minerals and deposits have some significant differences.The Nevada deposits were dominated by fluid-rock reaction in which host rock Fe was sulfidized to form Au-bearing pyrite.Although ore fluids sulfidized host rock Fe in the Guizhou deposits,the timing of Fe metasomatism is unknown,so whether the deposits formed in response to sulfidation or pyritization is unclear.Fluid-rock reaction between an acidic,aqueous fluid and highly reactive calcareous rocks in Nevada caused extensive decarbonatization of host rocks,jasperoid replacement of carbonate minerals,and alteration of silty rock components to illite and kaolinite.In Guizhou,CO2-bearing ore

  20. Application of disorganized monolayer films on gold electrodes to the prevention of surfactant inhibition of the voltammetric detection of trace metals via anodic stripping of underpotential deposits: detection of copper.

    Science.gov (United States)

    Herzog, Grégoire; Arrigan, Damien W M

    2003-01-15

    Development of an approach to prevention of electrode surface fouling by surfactants in samples is demonstrated. Spontaneously adsorbed monolayer systems employing short alkyl chains and bulky end groups are used to form porous disorganized monolayers on gold electrodes. Detection of copper by stripping of underpotential deposits formed at electrodes modified with disorganized films of mercaptoethanesulfonate (MES), mercaptopropanesulfonate, mercaptoacetic acid, and mercaptopropanoic acid was possible, and to a much lesser extent at aminoethanethiol and L-cysteine films. Use of short deposition times in conjunction with linear sweep anodic stripping voltammetry allowed detection of Cu2+ ions down to 1 x 10(-6) M in sulfuric acid solution, using underpotential deposition as the deposition step of the procedure. Calibration graphs were linear in the concentration range (1-80) x 10(-6) M Cu2+ using 15-s deposition at 0.00 V versus Ag/AgCl. The surfactants Tween 20, Tween 80, and Triton X-100 were found to have no affect on detection of Cu2+ ions in the calibration curve concentration range using MES-modified gold electrodes, whereas at unmodified gold electrodes very severe attenuation of the detection capability was manifested. The average slope for all calibration curves at the MES-modified electrode in the absence and presence of the surfactants at two different concentration levels was 0.0710 +/- 0.0024 microA microM(-1); in contrast, the slope of the calibration line at uncoated gold electrodes in the presence of surfactant was 0.0268 microA microM(-1). These results indicate the excellent ability of a disorganized, porous monolayer for prevention of fouling of the electrode surface by the surfactants.

  1. Metallogenic Conditions and Genesis of the Shangjiaoshan Gold Deposit in Du'an, Debao County, Guangxi%广西德保县都安三角山金矿的成矿条件及成因探讨

    Institute of Scientific and Technical Information of China (English)

    周方; 陈业余

    2011-01-01

    三角山金矿主要产于早泥盆系塘丁组的碎屑岩和泥质粉砂岩中,矿体严格受地层层位、断裂及褶皱等构造控制,矿石类型以泥质矿石为主,硅质矿石次之的氧化矿石.围岩成分主要为泥岩,泥质粉砂岩及硅质岩;围岩蚀变有硅化、褐铁矿化及粘土化.经过野外地质勘查,并结合前人资料对其成因进行分析,认为该区具有良好的金矿成矿地质条件,三角山金矿为微细浸染型金矿床,属于大气降水渗滤成因的中低温热液矿床.%The Sanjiaoshan gold deposit occurs mainly in the clasolite and pelitic siltstone in Tangding group in lower Devonian system which strictly controlled by strata, faults and folds. The types of ore are mainly argillaceous, and silica oxidized ores in less. The host rocks are pelite argillaceous siltite and sillcalite. The alterations of the host rock include silicification, limonitization and argillation. With field reconnaissance geological survey, this paper figures out good mineralization for gold mine in this area, and analyses the genesis of this gold deposit based on the information from former researchers, and suggests that this deposit belongs to Carlin type gold deposit, that's a minute dissemination medium-low hydrothermal deposit with atmospheric water filtering genesis.

  2. Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovic