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An extensive anoxic event in the Triassic of the South China Block : a pyrite framboid study form Dajiang and its implications for the cause(s) of oxygen depletion

Liao, Wei; Bond, David; Bond, David P.G.; Wang, Yongbiao; He, Lei; Yang, Hao; Weng, Zeting; Li, Guoshan

Authors

Wei Liao

Yongbiao Wang

Lei He

Hao Yang

Zeting Weng

Guoshan Li



Abstract

Water column oxygen deficiency has been considered as a potent driver of the extinction of marine benthos, and is a main feature of marine environments in the aftermath of the end-Permian mass extinction. The record of Permian-Triassic anoxia is more complex than previously thought, and is seen to vary between different palaeogeographic settings, but a full understanding is hindered by a paucity of evidence. During the Permian-Triassic interval the South China Block was located equatorially with Palaeotethys to the north and western Panthalassa to the south. This specific configuration provides a unique opportunity to compare the extent and duration of oxygen deficiency in Palaeotethys and Panthalassa under broadly similar climatic conditions. Sedimentary facies and pyrite framboid size-frequency distributions suggest that the oxygen-poor conditions became widespread across the shallow-marine carbonate platform of the South China Block immediately above the Permian-Triassic boundary and mass extinction level. Oxygen deficiency was most intense at the southern margin of the block where it met Panthalassa. Proposed drivers of the expansion of oxygen minimum zones into platform settings include enhanced terrigenous input and/or ocean stratification, or alternatively the upwelling of nutrient-rich deep ocean water. The former mechanisms are theoretically more likely to have operated in the relatively restricted Palaeotethys which was surrounded by ancient lands. In contrast, Panthalassa would likely have experienced stronger oceanic circulation and therefore be more susceptible to the effects of upwelling. Although variations in the record of the South China Block anoxic event might reflect local factors, the greater intensity of oxygen deficiency and a concomitant larger negative shift in carbonate carbon isotopes on its Panthalassan margin point to a key role for upwelling. This mechanism was likely a major driver of the Permian-Triassic global oceanic anoxic event, which itself was at least partly responsible for the ongoing inhospitable conditions and delayed recovery following the end-Permian extinction.

Journal Article Type Article
Publication Date Nov 15, 2017
Journal Palaeogeography, palaeoclimatology, palaeoecology
Print ISSN 0031-0182
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 486
Pages 86-95
Institution Citation Liao, W., Bond, D. P., Wang, Y., He, L., Yang, H., Weng, Z., & Li, G. (2017). An extensive anoxic event in the Triassic of the South China Block : a pyrite framboid study form Dajiang and its implications for the cause(s) of oxygen depletion. Palaeogeography, palaeoclimatology, palaeoecology, 486, 86-95. https://doi.org/10.1016/j.palaeo.2016.11.012
DOI https://doi.org/10.1016/j.palaeo.2016.11.012
Keywords Earth-Surface Processes; Palaeontology; Ecology, Evolution, Behavior and Systematics; Oceanography
Publisher URL http://www.sciencedirect.com/science/article/pii/S003101821630699X
Additional Information This article is maintained by: Elsevier; Article Title: An extensive anoxic event in the Triassic of the South China Block: A pyrite framboid study from Dajiang and its implications for the cause(s) of oxygen depletion; Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology; CrossRef DOI link to publisher maintained version: http://dx.doi.org/10.1016/j.palaeo.2016.11.012; Content Type: article; Copyright: © 2016 Elsevier B.V. All rights reserved.

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