Cookies

We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.


Durham Research Online
You are in:

Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction.

Them, Theodore R. and Gill, Benjamin C. and Caruthers, Andrew H. and Gerhardt, Angela M. and Gröcke, Darren R. and Lyons, Timothy W. and Marroquín, Selva M. and Nielsen, Sune G. and Trabucho Alexandre, João P. and Owens, Jeremy 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., 115 (26). pp. 6596-6601.

Abstract

For this study, we generated thallium (Tl) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; ∼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 Tl 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 Tl 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.

Item Type:Article
Full text:(AM) Accepted Manuscript
Download PDF
(1532Kb)
Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1073/pnas.1803478115
Date accepted:16 May 2018
Date deposited:04 September 2018
Date of first online publication:11 June 2018
Date first made open access:11 December 2018

Save or Share this output

Export:
Export
Look up in GoogleScholar