Oceanic redox conditions during the terminal Cambrian extinction event

Chen, Xi; Shields, Graham; Andersen, Morten B.; Qiu, Chen; Min, Si-Yu; Shao, Qingfeng

doi:10.1016/j.chemgeo.2023.121456

Cited by 4 publications

(1 citation statement)

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“…The period from the pre-Cambrian to the early Cambrian (equivalent to the Ediacaran to early Cambrian) represents a crucial time in global tectonic activity and sedimentary environmental changes [2][3][4][5][6]. It was characterized by the breakup and dispersal of the Rodinia supercontinent, the assembly of the Gondwana supercontinent [3,[7][8][9][10][11][12][13][14][15][16][17][18][19][20], as well as associated events such as widespread marine transgressions, hydrothermal activities, and episodes of persistent oceanic anoxia [21][22][23][24][25][26][27][28]. These events had a significant impact on the co-evolution of global geological environments and biota, leading to the widespread distribution of Lower Cambrian black shales.…”

Section: Introductionmentioning

confidence: 99%

Geochemical Characteristics and Geological Significance of Black Shale at the Bottom of the Mufushan Formation in the Lower Cambrian, Lower Yangtze Platform, South China

Kang

et al. 2023

Minerals

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Black shale, as an important unconventional energy resource, has attracted significant attention in recent years. By studying its sedimentary and geochemical characteristics, it is possible to reconstruct ancient depositional environments and paleoclimatic conditions. The Lower Cambrian black shale is widely distributed in the Lower Yangtze region, but its tectonic background and provenance have been subject to debate. In this study, we conducted geochemical testing and analysis on samples collected from the basal black shale of the Mufushan Formation in the Mufushan section, Nanjing. The Th/Sc-Zr/Sc diagram indicates that the black shale of the Mufushan Formation has not undergone sedimentary recycling. Analysis of major element ratios, rare earth element (REE) distribution patterns, δEu, (La/Yb)N, and the La/Th-Hf and La/Yb-∑REE discrimination diagrams suggest that the source rocks of the black shale mainly consist of granites and sedimentary rocks rich in ferromagnesian minerals, representing felsic rocks derived from the upper crust, with some involvement of mafic rocks. Considering the provenance attributes, geological age relationships, and tectonic evolution of the South China continent, the granite component in the source rocks is inferred to have formed during Neoproterozoic magmatic activity, and the source area corresponds to the Jiangnan Orogenic Belt. Analysis of K2O + Na2O-SiO2, K2O/Na2O-SiO2/Al2O3, La-Th-Sc, Th-Co-Zr/10, and Th-Sc-Zr/10 diagrams suggests that the source area of the Mufushan Formation black shale was a passive continental margin.

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