eprintid: 91503
rev_number: 60
eprint_status: archive
userid: 608
dir: disk0/00/09/15/03
datestamp: 2010-10-18 18:09:22
lastmod: 2021-09-19 22:59:21
status_changed: 2012-09-07 13:54:22
type: article
metadata_visibility: show
item_issues_count: 0
creators_name: van de Schootbrugge, B
creators_name: McArthur, JM
creators_name: Bailey, TR
creators_name: Rosenthal, Y
creators_name: Wright, JD
creators_name: Miller, KG
title: Toarcian oceanic anoxic event: An assessment of global causes using belemnite C isotope records
ispublished: pub
divisions: UCL
divisions: B04
divisions: C06
divisions: F57
keywords: Posidonia black shale, Whitby mudstone, SW-Germany, Organic-matter, Phytoplankton, Carbonates, England, Chemostratigraphy, Paleotemperatures, Sedimentary
note: Copyright 2005 by the American Geophysical Union
abstract: Two hypotheses have been proposed to explain simultaneous large negative excursions (up to 7% PeeDee belemnite) in bulk carbonate (delta(13)C(carb)) and organic carbon isotope records (delta(13)C(org)) from black shales marking the Toarcian oceanic anoxic event (T-OAE). The first explanation envisions recycling of dissolved inorganic carbon (DIC) with a light isotopic signature into the photic zone from the lower levels of a salinity-stratified water mass, essentially requiring a regional paleoceanographic driver of the carbon cycle. The second involves the rapid and massive dissociation of methane from gas hydrates that effectively renders the T-OAE a global perturbation of the carbon cycle. We present C isotope records from belemnites (delta(13)C(bel)) sampled from two localities, calibrated with high-resolution ammonite biostratigraphy and Sr isotope stratigraphy, in Yorkshire (England) and Dotternhausen (Germany), that can be used to assess which model best explains the observed changes in carbon isotopes. Our records of the delta(13)C composition of belemnite calcite do not show the large negative C isotope excursions shown by coeval records of delta(13)C in sedimentary organic matter or bulk sedimentary carbonate. It follows that isotopically light carbon cannot have dominated the ocean-atmosphere carbon reservoir during the Toarcian OAE, as would be required were the methane release hypothesis correct. On the basis of an evaluation of available carbon isotope records we discuss a model in which the recycling of DIC from the deeper levels of a stratified water body, and shallowing of anoxic conditions into the photic zone, can explain all isotopic profiles. In particular, the model accounts for the higher C isotope values of belemnites that are characteristic of open ocean, well-mixed conditions, and the lower C isotope values of neritic phytoplankton communities that recorded the degree of density stratification and shallowing of anoxia in the photic zone.
date: 2005-08-26
publisher: AMER GEOPHYSICAL UNION
official_url: http://dx.doi.org/10.1029/2004PA001102
vfaculties: VMPS
oa_status: green
language: eng
primo: open
primo_central: open_green
article_type_text: Article
verified: verified_batch
elements_source: Web of Science
elements_id: 56147
doi: 10.1029/2004PA001102
language_elements: EN
lyricists_name: McArthur, John
lyricists_id: JMMCA98
full_text_status: public
publication: Paleoceanography
volume: 20
number: 3
article_number: PA3008
issn: 0883-8305
citation:        van de Schootbrugge, B;    McArthur, JM;    Bailey, TR;    Rosenthal, Y;    Wright, JD;    Miller, KG;      (2005)    Toarcian oceanic anoxic event: An assessment of global causes using belemnite C isotope records.                   Paleoceanography , 20  (3)    , Article PA3008.  10.1029/2004PA001102 <https://doi.org/10.1029/2004PA001102>.       Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/91503/1/2004PA001102.pdf