The University of Southampton
University of Southampton Institutional Repository

Absence of major vegetation and palaeoatmospheric pCO2 changes associated with oceanic anoxic event 1a (Early Aptian, SE France)

Heimhofer, U., Hochuli, P.A., Herrle, J.O., Andersen, N. and Weissert, H. (2004) Absence of major vegetation and palaeoatmospheric pCO2 changes associated with oceanic anoxic event 1a (Early Aptian, SE France) Earth and Planetary Science Letters, 223, (3-4), pp. 303-318. (doi:10.1016/j.epsl.2004.04.037).

Record type: Article

Abstract

The deposition of organic-rich sediments during the late Early Aptian Oceanic Anoxic Event (OAE) 1a has been interpreted to result in a major decrease of palaeoatmospheric CO2 concentrations, accompanied by significant changes in the terrestrial flora. In order to test this hypothesis, the OAE 1a interval in the Vocontian Basin (SE France) has been studied with a combined approach including stable carbon isotopes, organic geochemistry and palynology. To estimate changes in palaeoatmospheric CO2 levels across the OAE 1a, the 13C composition of presumed algal biomarkers (low molecular weight n-alkanes, steranes) and of bulk carbonate carbon are used. Our results yield estimated Early Aptian carbon dioxide partial pressure (pCO2) values three to four times the preindustrial level and only a moderate drop across the black shale event. This moderate drop in pCO2 is supported by palynological results. The frequency patterns of climate-sensitive sporomorphs (incl. pteridophyte spores, bisaccate pollen and Classopollis spp.) display only minor fluctuations throughout the studied section and indicate relatively stable patterns of terrestrial vegetation during and after formation of the OAE 1a black shale. The occurrence of a characteristic Early Aptian carbon isotope pattern across the OAE 1a interval permits accurate chemostratigraphic correlation with the well-studied Livello Selli interval of the Cismon record (N Italy). The contemporaneous formation of individual black shale layers at both sites indicates that transient episodes of dysoxic–anoxic bottom waters prevailed over large areas in the W Tethys Ocean independent of depositional setting. Comparison of the palynological data from the two locations displays significant differences in the frequency patterns of bisaccate pollen. The contrasting pollen spectra are interpreted to reflect prominent changes in the palaeoceanographic current patterns and/or selective sorting due to sea-level rise rather than latitudinal shifts of the major floral belts.

Full text not available from this repository.

More information

Published date: 2004
Keywords: Early Cretaceous, Aptian, black shale, OAE, carbon isotope, palynology, organic geochemistry, palaeoatmosphere

Identifiers

Local EPrints ID: 15785
URI: http://eprints.soton.ac.uk/id/eprint/15785
ISSN: 0012-821X
PURE UUID: ef919fdd-5dbf-4e0d-9aa3-6745c4cc09db

Catalogue record

Date deposited: 31 May 2005
Last modified: 17 Jul 2017 16:46

Export record

Altmetrics

Contributors

Author: U. Heimhofer
Author: P.A. Hochuli
Author: J.O. Herrle
Author: N. Andersen
Author: H. Weissert

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×