Transient global cooling at the onset of early Aptian oceanic anoxic event (OAE) 1a.

Kuhnt, W., Holbourn, A. and Moullade, M. (2011) Transient global cooling at the onset of early Aptian oceanic anoxic event (OAE) 1a. Geology, 39 (4). pp. 323-326. DOI 10.1130/g31554.1.

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Abstract

The onset of the early Aptian oceanic anoxic event (OAE) 1a (ca. 120 Ma) coincided with a major perturbation of the carbon cycle, which is reflected in the sedimentary carbon isotope record. Triggering mechanisms, duration, and climatic repercussions of this episode of accelerated organic matter burial remain poorly constrained. Here, we present millennial-scale bulk rock carbon and oxygen isotope data from a marly subtropical intrashelf basin (La Bedoule, southeast France) with unusually high sedimentation rates, which track the onset of OAE1a in unprecedented resolution. Our record reveals that the negative, low-amplitude delta(13)C excursion preceding OAE1a lasted >100 k.y., implying that enhanced volcanic CO(2) emission and/or pulsed methane dissociation over a prolonged time span were instrumental in triggering OAE1a. The main positive carbon isotope shift at the onset of OAE1a, previously regarded as continuous, occurred stepwise over an extended period of >300 k.y. Transient climate cooling during the initial delta(13)C increase probably reflects ephemeral high-latitude glaciation, triggered by changes in radiative forcing and drawdown of atmospheric CO(2).

Document Type: Article
Additional Information: ISI Document Delivery No.: 736PT Times Cited: 0 Cited Reference Count: 27 Kuhnt, Wolfgang Holbourn, Ann Moullade, Michel Deutsche Forschungsgemeinschaft within the collaborative research center[SFB 754, TP A7] This research was funded by the Deutsche Forschungsgemeinschaft within the collaborative research center "Climate-Biogeochemistry Interactions in the Tropical Ocean" (SFB 754, TP A7). We thank Helmut Erlenkeuser and Nils Andersen (Leibniz Laboratory for Radiometric Dating and Stable Isotope Research) for stable isotope measurements. Geological soc amer, inc Boulder
Keywords: isotope record alpine tethys co2 stratigraphy consequences section carbon
Research affiliation: OceanRep > SFB 754 > A7
Kiel University
OceanRep > SFB 754
Refereed: Yes
DOI etc.: 10.1130/g31554.1
ISSN: 0091-7613
Projects: SFB754
Date Deposited: 15 Dec 2011 05:07
Last Modified: 18 May 2017 12:17
URI: http://oceanrep.geomar.de/id/eprint/15641

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