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Rapid warming and salinity changes of Cretaceous surface waters in the subtropical North Atlantic

Thomas Wagner, Jens O. Herrle, Jaap S. Sinninghe Damste, Stefan Schouten, Isabel Stuesser and Peter Hofmann
Rapid warming and salinity changes of Cretaceous surface waters in the subtropical North Atlantic
Geology (Boulder) (March 2008) 36 (3): 203-206

Abstract

Paleomarine carbon isotopic records reveal occasional and rapid release of greenhouse gases into the atmosphere. The regional consequences on surface ocean properties and time relationships between the atmosphere and the ocean, however, are still far from understood. We observe a sudden -1.5 per mil shift in leaf wax n-alkane (super 13) C values at the onset of oceanic anoxic event (OAE) 1b from early Albian sediments off northwest Africa (Deep Sea Drilling Project Site 545) that is best explained by the rapid release of isotopically light carbon into the Cretaceous atmosphere. This -1.5 per mil shift in the n-alkanes precedes a negative isotope excursion of similar magnitude observed in marine carbonate, organic matter, and algal steranes. A TEX (sub 86) -based record of sea surface temperature (SST) confirms almost instantaneous warming by approximately 3.5 degrees C along with the marine isotope shifts at Site 545, paralleled by an approximately 2 degrees C TEX (sub 86) -SST increase and a freshening of surface water salinity from 43 to 41 at Blake Nose, Ocean Drilling Program Site 1049. Multiproxy evidence indicates that, once established, these warm SSTs prevailed and were stable during OAE 1b, suggesting that the emission of (super 13) C-depleted carbon started abruptly but then continued over tens of thousands of years. The SST cooled by approximately 1-2 degrees C at the end of the event, not reaching pre-excursion levels. The new records provide evidence for a time lag (best estimate approximately 1-3 k.y.) between atmospheric and oceanic processes that we interpret as a direct response to changes in the atmospheric greenhouse gas concentrations followed by propagation into the ocean and subsequent heating of surface waters.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 36
Serial Issue: 3
Title: Rapid warming and salinity changes of Cretaceous surface waters in the subtropical North Atlantic
Affiliation: Newcastle University, School of Civil Engineering and Geosciences, Newcastle upon Tyne, United Kingdom
Pages: 203-206
Published: 200803
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 25
Accession Number: 2008-072105
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2008053
Illustration Description: illus. incl. sketch map
N33°39'51" - N33°39'52", W09°21'53" - W09°21'52"
N30°08'32" - N30°08'32", W76°06'44" - W76°06'44"
Secondary Affiliation: University of Alberta, CAN, CanadaRoyal Netherlands Institute for Sea Research, NLD, NetherlandsUniversity of Cologne, DEU, Federal Republic of Germany
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: 200819
Program Name: ODPOcean Drilling Program
Program Name: DSDPDeep Sea Drilling Project
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