Intensive ocean anoxia and large δ13Ccarb perturbations during the Carnian Humid Episode (Late Triassic) in Southwest China

Zhang Z, Joachimski M, Grasby SE, Sun Y (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Global and Planetary Change Elsevier

Original Authors: Z.T. Zhang, M.M. Joachimski, S.E. Grasby, Y.D. Sun

Book Volume: 217

Pages Range: 103942

Article Number: 103942

DOI: 10.1016/j.gloplacha.2022.103942

Abstract

The Carnian Humid Episode (CHE) represents a dramatic dry to wet climate transition in the Late Triassic. Manifestations of this climate shift and its associated biological and environmental responses are not fully understood. Here, we carried out carbonate carbon isotope, trace metal, and pyrite framboid analyses at Wolonggang in southwest China to trace palaeoenvironmental changes during this critical interval. The CHE at Wolonggang is marked by the development of fine laminated carbonaceous siltstones and black shales overlying the intensely bioturbated Zhuganpo limestone deposited in the latest Julian 1. This lithological change is accompanied by two negative δ13Ccarb excursions, a strong enrichment of redox-sensitive trace metals U and Mo, and the development of abundant small pyrite framboids with an average diameter < 5 μm. The sedimentary and geochemical evidence collectively suggest a sharp decrease in carbonate production and a major carbon cycle disturbance, coinciding with the onset of intense ocen anoxia and the mass mortality of burrowing faunas. Unlike other areas in the western Tethys, the aftermath of the CHE at Wolonggang is characterized by long-lasting ocean anoxia, with weak carbonate production persisting at least to the late Tuvalian. This is evidenced by the deposition of finely laminated silty carbonates, marls, and carbonaceous siltstones with rare benthic fossils in the Wayao Formation. Our study suggests that anoxic-euxinic environments widely developed along the southwest margins of the Yangtze Platform and in the Nanpanjiang Basin, probably contributing to the loss of marine faunas during the CHE.

Authors with CRIS profile

Michael Joachimski Lehrstuhl für Geologie (Exogene Dynamik) Yadong Sun Lehrstuhl für Geologie (Exogene Dynamik)

Involved external institutions

Geological Survey of Canada (GSC) / Commission géologique du Canada (CGC) CA Canada (CA) Wuhan Institute Of Geology And Mineral Resources, CGS, 中国地质调查局水文地质环境地质调查中心 CN China (CN)

How to cite

APA:

Zhang, Z., Joachimski, M., Grasby, S.E., & Sun, Y. (2022). Intensive ocean anoxia and large δ13Ccarb perturbations during the Carnian Humid Episode (Late Triassic) in Southwest China. Global and Planetary Change, 217, 103942. https://dx.doi.org/10.1016/j.gloplacha.2022.103942

MLA:

Zhang, Z.T, et al. "Intensive ocean anoxia and large δ13Ccarb perturbations during the Carnian Humid Episode (Late Triassic) in Southwest China." Global and Planetary Change 217 (2022): 103942.

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