Chen, W, Kemp, DB, He, T orcid.org/0000-0001-8975-8667 et al. (4 more authors) (2021) First record of the early Toarcian Oceanic Anoxic Event in the Hebrides Basin (UK) and implications for redox and weathering changes. Global and Planetary Change, 207. 103685. ISSN 0921-8181
Abstract
The early Toarcian (~183 Ma) was characterized by a prominent volcanism-induced warming event associated with a massive addition of 12C-enriched carbon to the ocean-atmosphere system. This warming likely contributed to marked ocean deoxygenation during this time, giving the event its name: the early Toarcian Oceanic Anoxic Event (T-OAE). Although the T-OAE has been recognized globally, clear geographic differences in the character of the event and its environmental effects have been noted. Here we present new carbon isotope, element abundance and organic geochemical data from a lower Toarcian succession on the Isle of Raasay, Scotland (Hebrides Basin, Northwest European Shelf). These data provide the first evidence of the T-OAE in Scotland. The succession is generally enriched in organic matter through the T-OAE interval, though redox-sensitive trace element data indicate that oxic-suboxic bottom water conditions prevailed, potentially interspersed with ephemeral anoxic episodes. Our elemental data contrast with evidence for persistent anoxia/euxinia in nearby basins, and emphasize how deoxygenation was spatially variable and dependent on water depth and basin hydrography. Similarly, the data emphasize how anoxia was not a prerequisite for the deposition of organic-rich lithologies during the T-OAE. Sedimentological evidence, coupled with inorganic geochemical data, indicates increased coarse-grained detrital flux and enhanced chemical weathering during the T-OAE. Our findings support emerging evidence for a marked strengthening of hydrological cycling and increased storminess at tropical and subtropical latitudes globally in response to global warming during the T-OAE.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Elsevier B.V. All rights reserved. This is an author produced version of an article published in Global and Planetary Change. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Toarcian OAE; Seawater redox conditions; Continental weathering changes; Geochemistry |
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 NERC (Natural Environment Research Council) NE/N018559/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 28 Oct 2021 15:29 |
Last Modified: | 27 Oct 2022 00:13 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.gloplacha.2021.103685 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:179491 |
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