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Volcanism, CO (sub 2) and palaeoclimate; a Late Jurassic-Early Cretaceous carbon and oxygen isotope record

Helmut Weissert and Elisabetta Erba
Volcanism, CO (sub 2) and palaeoclimate; a Late Jurassic-Early Cretaceous carbon and oxygen isotope record (in Organic-carbon burial, climate change and ocean chemistry (Mesozoic-Palaeogene), Helen S. Morgans-Bell (prefacer) and Anthony S. Cohen (prefacer))
Journal of the Geological Society of London (July 2004) 161 (4): 695-702

Abstract

A composite Tethyan Late Jurassic-Early Cretaceous carbon and oxygen isotope curve is presented. C-isotope data provide information on the evolution and perturbation of the global carbon cycle. O-isotope data are used as a paleotemperature proxy in combination with paleontological information. The resulting trends in climate and in paleoceanography are compared with biocalcification trends and oceanographic conditions favoring or inhibiting biocalcification. Positive C-isotope anomalies in the Valanginian and Aptian correlate with episodes of increased volcanic activity regarded as a source of excess atmospheric carbon dioxide. A major warming pulse accompanies the Aptian but not the Valanginian C-isotope event. The observed change in Early Aptian temperatures could have triggered the destabilization of sedimentary gas hydrates and the sudden release of methane to the biosphere as recorded as a distinct negative carbon isotope pulse preceding the positive excursion. Both C-isotope anomalies are accompanied by biocalcification crises that may have been triggered by pCO (sub 2) -induced changes in climate and in surface water chemistry. Elevated nutrient levels in river-influenced coastal waters and in upwelling regions further weakened marine calcification. These conditions contrast with "normal" trophic conditions prevailing in the latest Jurassic and favoring biocalcification. The C- and O-isotope curves record a stable mode of carbon cycling and stable temperatures. We conclude that biocalcification is mostly triggered (and inhibited) by CO (sub 2) conditions in the atmosphere-ocean system.


ISSN: 0016-7649
EISSN: 2041-479X
Coden: JGSLAS
Serial Title: Journal of the Geological Society of London
Serial Volume: 161
Serial Issue: 4
Title: Volcanism, CO (sub 2) and palaeoclimate; a Late Jurassic-Early Cretaceous carbon and oxygen isotope record
Title: Organic-carbon burial, climate change and ocean chemistry (Mesozoic-Palaeogene)
Author(s): Weissert, HelmutErba, Elisabetta
Author(s): Morgans-Bell, Helen S.prefacer
Author(s): Cohen, Anthony S.prefacer
Affiliation: ETH-Zentrum, Department of Earth Science, Zurich, Switzerland
Affiliation: University of Oxford, Dept. of Earth Sciences, Oxford, United Kingdom
Pages: 695-702
Published: 200407
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 76
Accession Number: 2004-061345
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N45°00'00" - N47°00'00", E08°00'00" - E12°00'00"
Secondary Affiliation: Open University, GBR, United KingdomUniversita di Milano, ITA, Italy
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 200418
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