Li, M, Song, H, Wignall, PB orcid.org/0000-0003-0074-9129 et al. (4 more authors) (Cover date: 1 Aug 2019) Early Triassic oceanic red beds coupled with deep sea oxidation in South Tethys. Sedimentary Geology, 391. 105519. ISSN 0037-0738
Abstract
Carbonate oceanic red beds (ORBs) are unusual in Phanerozoic shelf settings but can be widespread during discrete intervals. Several scenarios have been invoked to explain the origin of these ORBs but there remains uncertainty about the process by which the red pigmentation of ORBs forms. Here, we propose that the occurrence of ORBs at intermediate water depths in shelf regions is controlled by fluctuations in the redox state of deeper waters. We have examined Early Triassic Peri-Gondwana shelf sections in South Tibet which show the development of Spathian (late Early Triassic) ORBs at intermediate water depths. The red color of these ORBs is imparted by randomly dispersed hematite crystals that are microns in size, showing weak alteration by late burial diagenesis. Widespread anoxia, in both shelf seas and the oceanic realm, was well developed in the Early Triassic. Synchronous occurrence of Spathian ORBs in deep shelf regions is closely related to the improved oxidation in deeper settings, from anoxia to dysoxia, based on changes in the redox proxy of pyrite framboid sizes. It is, therefore, inferred that prolonged deep-water anoxia might serve as source of Fe (II) for the formation of ORBs when intensified upwelling develops. The global occurrence of Early Triassic ORBs is coincident with the significant rebound of biodiversity after the Permian-Triassic mass extinction, indicating the occurrence of ORBs marks the terminal stage of an oceanic anoxic event and ORBs can serve as an indicator of the ameliorated marine ecosystem.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Editors: |
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Copyright, Publisher and Additional Information: | © 2019 Elsevier B.V. All rights reserved. This is an author produced version of an article published in Sedimentary Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Oceanic red bed; Microfacies; Spathian; Deep water oxidation; Framboid pyrite |
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) > Institute for Applied Geosciences (IAG) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 18 Oct 2019 12:02 |
Last Modified: | 19 Aug 2020 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.sedgeo.2019.105519 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:152224 |