Bridger, P, Poulton, SW orcid.org/0000-0001-7621-189X, Zhou, Y et al. (3 more authors) (2022) The Ediacaran ‘Miaohe Member’ of South China: new insights from palaeoredox proxies and stable isotope data. Geological Magazine, 159 (7). pp. 1014-1028. ISSN 0016-7568
Abstract
Throughout the Ediacaran Period, variable water-column redox conditions persisted along productive ocean margins due to a complex interplay between nutrient supply and oceanographic restriction. These changing conditions are considered to have influenced early faunal evolution, with marine anoxia potentially inhibiting the development of the ecological niches necessary for aerobic life forms. To understand this link between oxygenation and evolution, the combined geochemical and palaeontological study of marine sediments is preferable. Located in the Yangtze Gorges region of southern China, lagoonal black shales at Miaohe preserve alga and putative metazoans, including Eoandromeda, a candidate total-group ctenophore, thereby providing one example of where integrated study is possible. We present a multi-proxy investigation into water-column redox variability during deposition of these shales (c. 560–551 Ma). For this interval, reactive iron partitioning indicates persistent water-column anoxia, while trace metal enrichments and other geochemical data suggest temporal fluctuations between ferruginous, euxinic and rare suboxic conditions. Although trace metal and total organic carbon values imply extensive basin restriction, sustained trace metal enrichment and δ15Nsed data indicate periodic access to open-ocean inventories across a shallow-marine sill. Lastly, δ13Corg values of between −35‰ and −40‰ allow at least partial correlation of the shales at Miaohe with Member IV of the Doushantuo Formation. This study provides evidence for fluctuating redox conditions in the lagoonal area of the Yangtze platform during late Ediacaran time. If these low-oxygen environments were regionally characteristic, then the restriction of aerobic fauna to isolated environments can be inferred.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s), 2021. Published by Cambridge University Press. This article has been published in a revised form in Geological Magazine https://doi.org/10.1017/S0016756821000261. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. |
Keywords: | carbon isotopes; chemostratigraphy; Doushantuo Formation; iron speciation; nitrogen isotopes; redox-sensitive trace metals |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Funding Information: | Funder Grant number Royal Society WM150108 |
Depositing User: | Symplectic Publications |
Date Deposited: | 17 Mar 2021 16:06 |
Last Modified: | 28 Jul 2022 10:36 |
Status: | Published |
Publisher: | Cambridge University Press |
Identification Number: | 10.1017/S0016756821000261 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:172258 |
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