Sedimentary exhalative nickel-molybdenum ores in South China

Lott, D. A.; Coveney, Raymond M.; Murowchick, James B.; Grauch, Richard I.

doi:10.2113/gsecongeo.94.7.1051

Cited by 113 publications

(42 citation statements)

References 18 publications

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“…Re/Os isotopic data from the Mo-Ni-PGE-rich sulphide layers suggest that most of the metal enrichment occurred soon after sediment deposition, probably during diagenesis (Horan et al 1994). A sedimentary exhalative depositional model involving submarine hydrothermal vents in shallow waters (< 250 m), with maximum temperatures near 266°C, was suggested by Lott et al (1999) and Steiner et al (2001). These authors also indicated the possibility that some ore constituents (i.e.…”

Section: Chinese Metal-rich Black Shalesmentioning

confidence: 96%

Fractionation of toxic trace elements in soils around Mo-Ni black shale-hosted mines, Zunyi region, southern China: Environmental implications.

Ponavic¹,

Pašava²,

Vymazalová³

et al. 2006

Bull. Geosci.

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This paper examines the influence of Lower Cambrian metal-rich black shales and locally mined black shale-hosted Ni-Mo ore layers of southern China on the concentrations of selected toxic trace elements in soils. In order to better understand the mobility of toxic trace elements, and to evaluate the potential risk of environmental contamination, a sequential extraction analysis from soil horizons A, B, C 1 and C 2 in the area of the Jiepo-Ling Mo-Ni mine (Zunyi region) was carried out. Geochemical analyses confirmed significant enrichments of As, Mo, V and slightly lower proportions of Pb and Ni in the A-horizon relative to a local reference sample of uncontaminated soil. This contamination is anthropogenic, probably caused by the release of metal-rich black shale particles during mining operations. Conversely, the distribution of V and Cr in soils is controlled by the host rock. The results of sequential extraction analyses from individual soil horizons showed that almost all As, Ni, V, Cr and Zn are bound to the residual fraction. Some of the Mo (15.13-39.75%) was found to be associated with the organic matter/sulphide fraction. The distribution of Pb and Hg is erratic, indicating considerable mobility of these elements in the soil profile. In Hg-enriched horizons (B and C 1 ) most Hg (78.21-78.95% of the total content) occurs in the organic matter/sulphide fraction. The concentrations of Mo, Ni, Cr, V, Zn and Hg found in different parts of selected agricultural plants (e.g., tobacco leaves, corn grains, corn leaves, and corn stalks) exceed normal values given by Kabata-Pendias & Pendias (1984). We emphasise that long-term consumption of these products could result in serious health problems for the human population and domestic animals. Arsenic and lead concentrations were found to be within the range of normal values given for agricultural plants.• Key words: metals in soils, extraction analyses, metal-rich black shales, environmental implications, south China.

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Section: Chinese Metal-rich Black Shalesmentioning

confidence: 96%

Fractionation of toxic trace elements in soils around Mo-Ni black shale-hosted mines, Zunyi region, southern China: Environmental implications.

Ponavic¹,

Pašava²,

Vymazalová³

et al. 2006

Bull. Geosci.

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“…A Ni-Mo enrichment layer along the transitional zone between the platform and basin was deposited under these euxinic conditions (Lehmann et al, 2007;Steiner et al, 2001). Previous studies argued that the Ni-Mo enrichments in the sediments could originate from hydrothermal input (Lott et al, 1999;Steiner et al, 2001), enrichment from seawater (Lehmann et al, 2007;Mao et al, 2002), or more likely the combination of both processes (Pašava et al, 2008). Recent studies demonstrated that the Ni-Mo sulfide ore layer, which is usually less than half meters in thickness (Jiang et al, 2006), has relatively lower ␦ 98 Mo values (<1.6‰) (Lehmann et al, 2007;Xu et al, 2012) (low-temperature hydrothermal fluids ␦ 98 Mo = +0.8‰, McManus et al, 2002), while black shales above and below this Ni-Mo ore layer have high ␦ 98 Mo values (∼1.9-2.4‰) (Chen et al, 2015) (modern seawater ␦ 98 Mo = +2.34‰, Goldberg et al, 2013), suggesting that hydrothermal input of Mo may have contributed only to the Ni-Mo ore layer, but not to the adjacent black shales (Chen et al, 2015).…”

Section: Cambrian Stagementioning

confidence: 97%

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

Wang

Struck

Guo

et al. 2015

Precambrian Research

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“…Mao et al , 2002;Lehmann et al , 2004 ) or from seawater enriched in metals through evaporation and/or hydrothermal input (e.g. Murowchick et al , 1994;Lott et al , 1999;Steiner et al , 2001;Pa š ava et al , 2004;Emsbo et al , 2005;Orberger et al , 2007 ) and terrigenous input (e.g. Jiang et al , 2006b ).…”

Section: Model Of Ore Formationmentioning

confidence: 99%

Multiple Sources of Metals of Mineralization in Lower Cambrian Black Shales of South China: Evidence from Geochemical and Petrographic Study

et al. 2008

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Black shales of the Lower Cambrian Niutitang Formation in southern China (Huangjiawan mine, Zunyi region, northern part of the Guizhou Province) host regionally distributed stratiform polymetallic Ni-Mo-platinum group elements (PGE)-Au phosphate-and sulfi de-rich ores. These are confi ned to a £ 0.2-m thick ore horizon composed of mineralized bodies of algal onkolites, phosphate nodules, and sulfi de and shale clasts in a mineralized phosphate-and organic matter-rich matrix. Compared to footwall and hanging wall shales, the ore bed is strongly enriched in Ni (up to 100-fold), As (up to 97-fold), Mo (up to 95-fold), Sb (up to 67-fold), Rh (up to 49-fold), Cu (up to 37-fold), Pd (up to 33-fold), Ru (up to 24-fold), Zn (up to 23-fold), Pt (up to 21-fold), Ir (up to 15-fold), Co (up to 14-fold), and Pb (up to 13-fold). Even footwall and hanging wall black shales are signifi cantly enriched by Mo (21-fold) and Ni (12-fold) but depleted in Cr in comparison to average Cambrian black shale. Organic matter is represented by separate accumulations dispersed in the rock matrix or as biotic bitumen droplets and veinlets in ore clasts. Similar organic carbon (C org ) values in an ore bed and enclosing footwall and hanging wall shales of little mineralization indicate that metal accumulation was not controlled only by biogenic productivity and organic matter accumulation rate. Evaporitic conditions during sedimentation of the basal part of the Niutitang Formation were documented by an occurrence of preserved Ni-, V-, Cr-, and Cu-enriched phosphate-rich hardground with halite and anhydrite pseudomorphs on the paleosurface of the underlying Neoproterozoic carbonates. Neoproterozoic black shales of the Doushantuo Formation are characterized by increased metal concentrations. Comparison of metal abundances in both hardground and Doushantuo black shales indicate that black shales could have become a source of metal-rich hardground during weathering. The polymetallic Ni-Mo-PGE sulfi de-rich ore bed is interpreted to represent a remnant of shallow-water hardground horizon rich in metals, which originated in a sediment-starved, semi-restricted, seawater environment. During the Early Cambrian transgression an infl ux of fresh seawater and intensive evaporation, together with the hydrothermal enrichment of seawater in a semi-restricted basin, resulted in the formation of dense metalliferous brines; co-precipitation of metals together with phosphates and sulfi des occurred at or above the oxic -anoxic sediment interface. Metal-enriched hardground was disintegrated by the action of waves or bottom currents and deposited in a deeper part of the anoxic basin. Contemporaneously with the formation of a polymetallic Ni-Mo-PGE-Au sulfi de ore bed, economic sedimentary exhalative

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Sedimentary exhalative nickel-molybdenum ores in South China

Cited by 113 publications

References 18 publications

Fractionation of toxic trace elements in soils around Mo-Ni black shale-hosted mines, Zunyi region, southern China: Environmental implications.

Fractionation of toxic trace elements in soils around Mo-Ni black shale-hosted mines, Zunyi region, southern China: Environmental implications.

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

Multiple Sources of Metals of Mineralization in Lower Cambrian Black Shales of South China: Evidence from Geochemical and Petrographic Study

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