A review of polymetallic mineralization in lower Cambrian black shales in South China: Combined effects of seawater, hydrothermal fluids, and biological activity

Shi, Chunhua; Cao, Jian; Han, Shanchu; Hu, Kai; Bian, Lizeng; Yao, Shuzhen

doi:10.1016/j.palaeo.2020.110073

Cited by 25 publications

(17 citation statements)

References 66 publications

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“…The development of black shales mostly occurs during particular periods of geological history, and they not only record the changes in the paleoenvironment, paleoclimate, and paleontology, but also contain large quantities of metal-rich minerals and oil and gas resources [1][2][3][4]. The Early Cambrian Niutitang black shale in the Guizhou Province and northwest Hubei Province is an iconic deposit dating from the Neoproterozoic to the Early Paleozoic Era in Southern China [5,6].…”

Section: Introductionmentioning

confidence: 99%

Depositional Environment and Organic Matter Enrichment of Early Cambrian Niutitang Black Shales in the Upper Yangtze Region, China

et al. 2022

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Natural gas generation is the result of organic matter degradation under the effects of biodegradation and thermal degradation. Early Cambrian black shales in the Upper Yangtze Region are rich in organic matter and have shown great shale gas potentiality in recent years. Nevertheless, the enrichment mechanism and distribution of organic matter in these black shales between different sedimentary settings, such as intra-platform basin, slope, and deep basin, are still poorly understood. In this paper, based mainly on elemental geochemistry, a comprehensive study of the marine redox conditions, primary productivity, sedimentation rate, terrigenous input, hydrothermal activity, and water mass restrictions was conducted on the Early Cambrian Niutitang black shale in the Upper Yangtze Region. Our data showed that an intra-platform basin received a higher terrigenous input and that it deposited under more restricted conditions than the slope and deep basin settings. The primary productivity in the slope and deep basin settings was higher than that in the intra-platform basin setting. In the intra-platform basin, the productivity increased from its inner part to its margin. For the slope and deep basin settings, the high paleoproductivity generated large amounts of organic matter and its preservation was synergistically affected by the redox conditions. In contrast to the slope and deep basin, the preservation of organic matter in the inner part of the intra-platform basin was mainly controlled by redox conditions because the paleoproductivity in it was much lower than in the slope and deep basin settings. The intra-platform basin margin was the most favorable area for accumulating organic matter.

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Section: Introductionmentioning

confidence: 99%

Depositional Environment and Organic Matter Enrichment of Early Cambrian Niutitang Black Shales in the Upper Yangtze Region, China

et al. 2022

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“…4), the large-scale mineralization of barite deposits may have taken place earlier than the deposition of the polymetallic Ni-Mo-PGE and/or V-enriched layers of the basal Niutitang Formation. The offset in timing probably resulted from differential elemental concentration most likely related to the certain local factors (i.e., hydrothermal fluids, seawater redox and biological activity) (e.g., Shi et al, 2021;Han et al, 2017;Chen et al, 2009). In addition, the barite deposits initially occur in the middle-upper part of the Liuchapo Formation, and show an improvement in ore grade and a decreasing-upward thickness of chert, indicating the localized variations of paleogeography and seawater chemistry (e.g., Li et al, 2020Li et al, , 2010bHuang et al, 2019).…”

Section: Discussion 41 Geochronological Framework and Regional Strati...mentioning

confidence: 99%

“…In the Yangtze Block, the Lower Cambrian polymetallic Ni-Mo-PGE layer was considered as the marker horizon for the boundary between Ediacaran and Cambrian (e.g., Shi et al, 2021;Jiang et al, 2009;Li et al, 2003;Mao et al, 2002). More recently, the zircon U-Pb ages and Re-Os ages derived from the Liuchapo Formation and the base of the overlying Niutitang Formation of deep-water settings, however, suggested that the E-C boundary should be placed within the Liuchapo Yong Fu, Fuliang Wang, Chuan Guo, Chao Li and Peng Xia Formation (e.g., Wang W et al, 2020;Yang et al, 2017;Fu et al, 2016;Chen et al, 2015;Wang X Q et al, 2012;Xu et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Re-Os Geochronology of the Liuchapo Formation across the Ediacaran-Cambrian Boundary of the Yangtze Block (South China)

Wang

Guo

et al. 2022

J. Earth Sci.

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The Ediacaran-Cambrian (E-C) succession in South China records remarkable oceanic, biological and geochemical variations, but it was not well defined geochronologically, which hinders the interpretation of the spatio-temporal seawater chemical architecture during the time E-C interval. This study presents two Re-Os isochron ages of 520.2 ± 6.1 and 561.7 ± 8.5 Ma for the barite-rich black shales from the top Liuchapo and Doushantuo formations respectively in Tianzhu County, Guizhou Province. In combination with existing age data, the two new Re-Os isochron ages suggest that the Liuchapo Formation was deposited between 550 and 520 Ma. Moreover, like the polymetallic Ni-Mo-PGE layers of shelf margin (or platform) facies and V-rich horizons of transitional (or shelf slope) to deep-water facies, the barite deposits were likely formed due to differential mineralization. The timing offset likely resulted from differential elemental concentration related to certain local factors (i.e., hydrothermal fluids, seawater redox and biological activity). The isochron-derived initial 187Os/188Os ratios of the top Liuchapo Formation (0.902 ± 0.048) and the Doushantuo Formation (0.740 ± 0.042) fall within the range of continental weathering flux (1.54) and oceanic crust (0.126), implying the involvement of marine hydrothermal fluids. Moreover, their difference of initial 187Os/188Os ratios may reflect variations of continental weathering intensity and uplift magnitude.

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“…And trace elements such as Sr, Ba, U, Mo, V, Be, and Mo are also enriched in different lithofacies units. There are various types of polymetallic mineralization in lower Cambrian black rock series from South China, including Ni-Mo, Ba, P, and V deposits, which are controlled by three factors (seawater-hydrothermal fluids-biological activity) (Shi et al 2021). The comprehensive ore-bearing evaluation of this black rock series shows that Mo has the best metallogenic potential, followed by Cu, V, U, Sn, and Tl, followed by Pb and Li, while Sr, Zn, B, Th, and Rb also have certain metallogenic potential (Cheng et al 2020).…”

Section: Elements Anomaly and Hydrothermal Activitymentioning

confidence: 99%

Geochemical characteristics of the lower Cambrian Qiongzhusi Formation in Huize area, east Yunnan: implications for paleo-ocean environment and the origin of black rock series

Cheng

Liu

et al. 2021

Arab J Geosci

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The lower Cambrian black rock series in eastern Yunnan province is a high-quality shale gas reservoir with great prospect for oilgas exploration. However, the depositional conditions and mechanisms of organic matter enrichment are not well understood. In this study, geochemical characteristics of total organic carbon (TOC) and major and trace elements of fourteen black rock series samples from Dahai outcrop in eastern Yunnan province are systematically investigated to analyze the paleoenvironment and their effects on organic matter enrichment and established the accumulation model of organic matter. Results show that TOC contents of the four lithologic units of Qiongzhusi Formation black rock series are 0.70, 0.34, 1.77, and 0.27, respectively, which suggests that TOC content is generally low (mean = 0.51%). The main elements show that P 2 O 5 , CaO, and MgO are relatively rich, whereas other elements depleted. The enrichment factors (EFs) of trace elements showed that Pb and Zn are highly enriched in all samples, and Cu, Sr, Ba, U, Mo, V, Be, and Mo are also enriched in different lithofacies units. The elemental anomalies may be related to hydrothermal activities, which may lead to the distortion of some paleoenvironmental indicators to some extent. The Rb/Sr and Sr/Cu values show that the palaeoclimate gradually changed from dry to humid. Al concentrations indicate a gradual increase in terrigenous detritus supply. The hydrodynamic conditions and sedimentation rates implied by Zr/Al and Ti/Al values correspond well with lithology and grain size. Based on the comprehensive analysis of B/Ga and Sr/Ba ratios, it is considered that the black rock series in Qiongzhusi Formation was mainly formed in brachial water. Multiple paleoredox indicators (e.g., Ni/Co, V/Cr, U/Th, and V/(V+Ni) ratios) suggest that the sedimentary environment is mainly oxidized, which is usually considered unfavorable for organic matter preservation, and it also forms carbonaceous shale (unit 3) in a dysoxic environment. The Mo/ TOC ratios suggest that the sedimentation during Qiongzhusi Formation period was under restricted conditions. The paleoproductivity indicated by P/Ti, Ni/Al and Ba bio values decreased gradually from medium level to low level. In summary, relatively high paleoproductivity is a prerequisite for organic matter accumulation and less terrigenous debris supply, and relatively arid climate and reductive conditions are favorable for the preservation of organic matter.

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A review of polymetallic mineralization in lower Cambrian black shales in South China: Combined effects of seawater, hydrothermal fluids, and biological activity

Cited by 25 publications

References 66 publications

Depositional Environment and Organic Matter Enrichment of Early Cambrian Niutitang Black Shales in the Upper Yangtze Region, China

Depositional Environment and Organic Matter Enrichment of Early Cambrian Niutitang Black Shales in the Upper Yangtze Region, China

Re-Os Geochronology of the Liuchapo Formation across the Ediacaran-Cambrian Boundary of the Yangtze Block (South China)

Geochemical characteristics of the lower Cambrian Qiongzhusi Formation in Huize area, east Yunnan: implications for paleo-ocean environment and the origin of black rock series

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