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A volcanic CO (sub 2) pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis

Sabine Mehay, Christina E. Keller, Stefano M. Bernasconi, Helmut Weissert, Elisabetta Erba, Cinzia Bottini and Peter A. Hochuli
A volcanic CO (sub 2) pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis
Geology (Boulder) (September 2009) 37 (9): 819-822

Abstract

The Aptian Oceanic Anoxic Event 1a (OAE1a, ca. 120 Ma ago) is one of the most prominent of a series of geologically brief intervals in the Cretaceous characterized by the deposition of organic carbon-rich sediments. OAEs reflect major perturbations in the global carbon cycle evidenced by sedimentary carbon isotope records. However, the triggering mechanisms for OAEs remain controversial. Here we present a bulk-rock and molecular (marine and terrestrial bio-markers) C isotope record at unprecedented time resolution, from the Cismon section of northern Italy, that shows that OAE1a conditions were reached over a period of several thousands of years through a stepwise perturbation of the carbon cycle. The documented sequence of events is most compatible with a trigger associated with increased CO (sub 2) emissions, possibly leading to a doubling of pCO (sub 2) , which in turn caused larger C isotope fractionation in marine and terrestrial organisms and a major biotic crisis in the calcareous nannoplankton. Our data also show that a release of isotopically light carbon from partial methane hydrate dissociation probably played a minor role in the OAE1a carbon cycle perturbation.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 37
Serial Issue: 9
Title: A volcanic CO (sub 2) pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis
Affiliation: ETH Zuerich, Geological Institute, Zurich, Switzerland
Pages: 819-822
Published: 200909
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2009-088600
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2009200
Illustration Description: illus.
N44°47'60" - N46°40'60", E10°40'00" - E13°04'60"
Secondary Affiliation: University of Milan, ITA, ItalyUniversity of Zurich, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200948
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