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Thallium Isotopes Reveal Protracted Anoxia During The Toarcian (early Jurassic) Associated With Volcanism, Carbon Burial, And Mass Extinction

Title: Thallium Isotopes Reveal Protracted Anoxia During The Toarcian (early Jurassic) Associated With Volcanism, Carbon Burial, And Mass Extinction.
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Name(s): Them, Theodore R., author
Gill, Benjamin C., author
Caruthers, Andrew H., author
Gerhardt, Angela M., author
Grocke, Darren R., author
Lyons, Timothy W., author
Marroquin, Selva M., author
Nielsen, Sune G., author
Alexandre, Joao P. Trabucho, author
Owens, Jeremy D., author
Type of Resource: text
Genre: Journal Article
Text
Journal Article
Date Issued: 2018-06-26
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: For this study, we generated thallium (TI) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; similar to 183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our TI isotope data, however, reveal explicit evidence for earlier global marine deoxygenation of ocean water, some 600 ka before the classically defined T-OAE. This antecedent deoxygenation occurs at the Pliensbachian/Toarcian boundary and is coeval with the onset of initial large igneous province (LIP) volcanism and the initiation of a marine mass extinction. Thallium isotopes are also perturbed during the T-OAE interval, as defined by carbon isotopes, reflecting a second deoxygenation event that coincides with the acme of elevated marine mass extinctions and the main phase of LIP volcanism. This suggests that the duration of widespread anoxic bottom waters was at least 1 million years in duration and spanned early to middle Toarcian time. Thus, the TI data reveal a more nuanced record of marine oxygen depletion and its links to biological change during a period of climatic warming in Earth's past and highlight the role of oxygen depletion on past biological evolution.
Identifier: FSU_libsubv1_wos_000436245000051 (IID), 10.1073/pnas.1803478115 (DOI)
Keywords: resolution, marine-sediments, preservation, Early Jurassic, organic-matter, fractionation, cycle, event, carbon isotope excursion, large igneous province, oceanic oxygen, proxy, stage, thallium isotopes, Toarcian Oceanic Anoxic Event
Publication Note: The publisher’s version of record is available at https://doi.org/10.1073/pnas.1803478115
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000436245000051
Owner Institution: FSU
Is Part Of: Proceedings of the National Academy of Sciences of the United States of America.
0027-8424
Issue: iss. 26, vol. 115

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Them, T. R., Gill, B. C., Caruthers, A. H., Gerhardt, A. M., Grocke, D. R., Lyons, T. W., … Owens, J. D. (2018). Thallium Isotopes Reveal Protracted Anoxia During The Toarcian (early Jurassic) Associated With Volcanism, Carbon Burial, And Mass Extinction. Proceedings Of The National Academy Of Sciences Of The United States Of America. Retrieved from http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000436245000051