Boomer, I;
Copestake, P;
Page, K;
Huxtable, J;
Loy, T;
Bown, P;
Dunkley Jones, T;
... Caughtry, N; + view all
(2021)
Biotic and stable-isotope characterization of the Toarcian Ocean Anoxic Event through a carbonate–clastic sequence from Somerset, UK.
Geological Society, London, Special Publications
, 514
(1)
, Article 239. 10.1144/sp514-2020-263.
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Abstract
This study focuses on a condensed sequence of alternating carbonate–clastic sediments of the Barrington Member, Beacon Limestone Formation (latest Pliensbachian to early Toarcian) from Somerset (SW England). Abundant ammonites confirm (apart from the absence of the Clevelandicum and Tenuicostatum ammonite subchronozones) the presence of Hawskerense Subchronozone to Fallaciosum–Bingmanni subchronozones. Well-preserved, sometimes diverse assemblages of ostracods, foraminifera, nannofossils and lowdiversity dinoflagellate assemblages support the chronostratigraphic framework. Stable-isotope analyses demonstrate the presence of a carbon isotope excursion, relating to the Toarcian Oceanic Anoxic Event, within the early Toarcian. Faunal, geochemical and sedimentological evidence suggest that deposition largely took place in a relatively deep-water (subwave base), mid-outer shelf environment under a well-mixed water column. However, reduced benthic diversity, the presence of weakly laminated sediments and changes in microplankton assemblage composition within the Toarcian Oceanic Anoxic Event indicates dysoxic, but probably never anoxic, bottom-water conditions during this event. The onset of the carbon isotope excursion coincides with extinction in the nannofossils and benthos, including the disappearance of the ostracod suborder Metacopina. Faunal evidence indicates connectivity with the Mediterranean region, not previously recorded for the UK during the early Toarcian.
| Type: | Article |
|---|---|
| Title: | Biotic and stable-isotope characterization of the Toarcian Ocean Anoxic Event through a carbonate–clastic sequence from Somerset, UK |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1144/sp514-2020-263 |
| Publisher version: | http://dx.doi.org/10.1144/sp514-2020-263 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10128254 |
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