Gold in the oceans through time

Large, Ross R.; Gregory, Daniel D.; Steadman, Jeffrey A.; Tomkins, Andrew G.; Lounejeva, E; Danyushevsky, Leonid V.; Halpin, Jacqueline A.; Масленников, В. В.; Sack, Patrick J.; Mukherjee, Indrani; Berry, Ron F.; Hickman, Arthur H.

doi:10.1016/j.epsl.2015.07.026

Cited by 72 publications

(30 citation statements)

References 50 publications

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“…Supplementary Materials: The following are available online at http://www.mdpi.com/2075-163X/10/7/588/s1, Table S1: Pyrite LA-ICP-MS analyses in Bijaigarh shales in ppm, Table S2: Mean trace element concentrations of fine-grained pyrite vs pyrite lag, Table S3: Mean trace elements in this study compared to mean pyrite analyses by [16][17][18][19]; concentrations are in ppm, Table S4: SHRIMP-SI pyrite analyses in AJ15/1, AJ/154i, AJ15/3iii in % .…”

Section: Discussionmentioning

confidence: 99%

“…Black shales also allow application of certain geochronological techniques, such as Re-Os, to acquire good age constraints. More recently, trace elements in sedimentary pyrite associated with black shales have been used to understand the paleo atmosphere-ocean redox conditions, as pyrite is an excellent host for most redox sensitive trace elements [16][17][18][19][20][21]. Apart from trace element concentrations, sedimentary pyrite textures provide insights into depositional conditions and paleo-biological conditions, i.e., when pyritized microbial textures are present.…”

Section: Introductionmentioning

confidence: 99%

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Pyrite Textures, Trace Elements and Sulfur Isotope Chemistry of Bijaigarh Shales, Vindhyan Basin, India and Their Implications

et al. 2020

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The Vindhyan Basin in central India preserves a thick (~5 km) sequence of sedimentary and lesser volcanic rocks that provide a valuable archive of a part of the Proterozoic (~1800–900 Ma) in India. Here, we present an analysis of key sedimentary pyrite textures and their trace element and sulfur isotope compositions in the Bijaigarh Shale (1210 ± 52 Ma) in the Vindhyan Supergroup, using reflected light microscopy, LA-ICP-MS and SHRIMP-SI, respectively. A variety of sedimentary pyrite textures (fine-grained disseminated to aggregates, framboids, lags, and possibly microbial pyrite textures) are observed reflecting quiet and strongly anoxic water column conditions punctuated by occasional high-energy events (storm incursions). Key redox sensitive or sensitive to oxidative weathering trace elements (Co, Ni, Zn, Mo, Se) and ratios of (Se/Co, Mo/Co, Zn/Co) measured in sedimentary pyrites from the Bijaigarh Shale are used to infer atmospheric redox conditions during its deposition. Most trace elements are depleted relative to Proterozoic mean values. Sulfur isotope compositions of pyrite, measured using SHRIMP-SI, show an increase in δ34S as we move up stratigraphy with positive δ34S values ranging from 5.9‰ (lower) to 26.08‰ (upper). We propose limited sulphate supply caused the pyrites to incorporate the heavier isotope. Overall, we interpret these low trace element signatures and heavy sulfur isotope compositions to indicate relatively suppressed oxidative weathering on land during the deposition of the Bijaigarh Shale.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pyrite Textures, Trace Elements and Sulfur Isotope Chemistry of Bijaigarh Shales, Vindhyan Basin, India and Their Implications

et al. 2020

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“…These orogens, commonly termed greenstone belts, are composed mostly of oceanic rocks, such as basaltic lavas and sedimentary rocks. Although orogens cover the entire geological age spectrum [13], orogenic gold deposits are distributed in three main periods (Figure 2; [14,15] [16]) in relation to gold contents of nodular pyrites from black shales (2-geometric mean of LA-ICP-MS analyses from time interval: [16], an estimate of oxygenation based on Se content of nodular pyrite, expressed as a percentage of present atmosphere level (% PAL-3- [17]), and O2 whiffs and Canfield ocean (4- [18]). The high levels of Au in black shales correspond to the greatest periods for orogenic gold deposit formation.…”

Section: Orogenic Gold Depositsmentioning

confidence: 99%

“…In some particular cases, gold-bearing magmatic fluids can be mixed with metamorphic fluids to form orogenic gold deposits (e.g., [29]). [16]) in relation to gold contents of nodular pyrites from black shales (2-geometric mean of LA-ICP-MS analyses from time interval: [16]), an estimate of oxygenation based on Se content of nodular pyrite, expressed as a percentage of present atmosphere level (% PAL-3- [17]), and O 2 whiffs and Canfield ocean (4- [18]). The high levels of Au in black shales correspond to the greatest periods for orogenic gold deposit formation.…”

Section: Orogenic Gold Depositsmentioning

confidence: 99%

The Neglected Involvement of Organic Matter in Forming Large and Rich Hydrothermal Orogenic Gold Deposits

Gaboury¹

2021

Geosciences

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Orogenic gold deposits have provided most of gold to humanity. These deposits were formed by fluids carrying dissolved gold at temperatures of 200–500 °C and at crustal depths of 4–12 km. The model involves gold mobilization as HS− complexes in aqueous solution buffered by CO2, with gold precipitation following changes in pH, redox activity (fO2), or H2S activity. In this contribution, the involvement of carbonaceous organic matter is addressed by considering the formation of large and/or rich orogenic gold deposits in three stages: the source of gold, its solubilization, and its precipitation. First, gold accumulates in nodular pyrite within carbonaceous-rich sedimentary rocks formed by bacterial reduction of sulfates in seawater in black shales. Second, gold can be transported as hydrocarbon-metal complexes and colloidal gold nanoparticles for which the hydrocarbons can be generated from the thermal maturation of gold-bearing black shales or from abiotic origin. The capacity of hydrocarbons for solubilizing gold is greater than those of aqueous fluids. Third, gold can be precipitated efficiently with graphite derived from fluids containing hydrocarbons or by reducing organic-rich rocks. Black shales are thus a key component in the formation of large and rich orogenic gold deposits from the standpoints of source, transport, and precipitation. Unusual CO2-rich, H2O-poor fluids are documented for some of the largest and richest orogenic gold deposits, regardless of their age. These fluids are interpreted to result from chemical reactions involving hydrocarbon degradation, hence supporting the fundamental role of organic matter in forming exceptional orogenic gold deposits.

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“…The analysis of trace element (TE) contents in different generations of pyrite by use of high-resolution laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) has aided constructions of ore deposits models and helped to solve conjecture related to ore genesis [1][2][3][4][5][6][7][8][9] and paleoocean geochemical features [10].…”

Section: Introductionmentioning

confidence: 99%

Pyrite Varieties at Pobeda Hydrothermal Fields, Mid-Atlantic Ridge 17°07′–17°08′ N: LA-ICP-MS Data Deciphering

et al. 2020

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The massive sulfide ores of the Pobeda hydrothermal fields are grouped into five main mineral microfacies: (1) isocubanite-pyrite, (2) pyrite-wurtzite-isocubanite, (3) pyrite with minor isocubanite and wurtzite-sphalerite microinclusions, (4) pyrite-rich with framboidal pyrite, and (5) marcasite-pyrite. This sequence reflects the transition from feeder zone facies to seafloor diffuser facies. Spongy, framboidal, and fine-grained pyrite varieties replaced pyrrhotite, greigite, and mackinawite “precursors”. The later coarse and fine banding oscillatory-zoned pyrite and marcasite crystals are overgrown or replaced by unzoned subhedral and euhedral pyrite. In the microfacies range, the amount of isocubanite, wurtzite, unzoned euhedral pyrite decreases versus an increasing portion of framboidal, fine-grained, and spongy pyrite and also marcasite and its colloform and radial varieties. The trace element characteristics of massive sulfides of Pobeda seafloor massive sulfide (SMS) deposit are subdivided into four associations: (1) high temperature—Cu, Se, Te, Bi, Co, and Ni; (2) mid temperature—Zn, As, Sb, and Sn; (3) low temperature—Pb, Sb, Ag, Bi, Au, Tl, and Mn; and (4) seawater—U, V, Mo, and Ni. The high contents of Cu, Co, Se, Bi, Te, and values of Co/Ni ratios decrease in the range from unzoned euhedral pyrite to oscillatory-zoned and framboidal pyrite, as well as to colloform and crystalline marcasite. The trend of Co/Ni values indicates a change from hydrothermal to hydrothermal-diagenetic crystallization of the pyrite. The concentrations of Zn, As, Sb, Pb, Ag, and Tl, as commonly observed in pyrite formed from mid- and low-temperature fluids, decline with increasing crystal size of pyrite and marcasite. Coarse oscillatory-zoned pyrite crystals contain elevated Mn compared to unzoned euhedral varieties. Framboidal pyrite hosts maximum concentrations of Mo, U, and V probably derived from ocean water mixed with hydrothermal fluids. In the Pobeda SMS deposit, the position of microfacies changes from the black smoker feeder zone at the base of the ore body, to seafloor marcasite-pyrite from diffuser fragments in sulfide breccias. We suggest that the temperatures of mineralization decreased in the same direction and determined the zonal character of deposit.

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Gold in the oceans through time

Cited by 72 publications

References 50 publications

Pyrite Textures, Trace Elements and Sulfur Isotope Chemistry of Bijaigarh Shales, Vindhyan Basin, India and Their Implications

Pyrite Textures, Trace Elements and Sulfur Isotope Chemistry of Bijaigarh Shales, Vindhyan Basin, India and Their Implications

The Neglected Involvement of Organic Matter in Forming Large and Rich Hydrothermal Orogenic Gold Deposits

Pyrite Varieties at Pobeda Hydrothermal Fields, Mid-Atlantic Ridge 17°07′–17°08′ N: LA-ICP-MS Data Deciphering

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