HR: 1340h
AN: PP43B-1258    [Abstracts]
TI: The Enigmatic Beginning of the Aptian Carbon-Cycle Perturbation
AU: * Méhay, S
EM: sabine.mehay@erdw.ethz.ch
AF: ETH Zurich, Geological Institute, Universitätstrasse 16, Zurich, 8092, Switzerland
AU: Keller, C
EM: christina.keller@erdw.ethz.ch
AF: ETH Zurich, Geological Institute, Universitätstrasse 16, Zurich, 8092, Switzerland
AU: Bernasconi, S
EM: stefano.bernasconi@erdw.ethz.ch
AF: ETH Zurich, Geological Institute, Universitätstrasse 16, Zurich, 8092, Switzerland
AU: Weissert, H
EM: helmut.weissert@erdw.ethz.ch
AF: ETH Zurich, Geological Institute, Universitätstrasse 16, Zurich, 8092, Switzerland
AB: The Mid-Cretaceous is known as a period of dramatic carbon cycle perturbations, recorded in the δ¹³C values of both carbonate and organic matter in pelagic sediments. In particular, the Early Aptian exhibits a prominent negative δ¹³C spike, which precedes a positive carbon excursion. If the latter is assumed to be the result of an increased burial of organic matter caused by a greenhouse climate, the origin of this negative δ¹³C spike remains enigmatic. A simultaneous δ¹³C shift in both terrestrial and marine organic matter has been recorded at that time, indicating a substantial and abrupt input of isotopically light carbon, from ¹³C-depleted carbon sources to the ocean-atmosphere reservoir, may have happened at the onset of Early Aptian. Methane hydrates trapped in continental margin sediments are thought to have been released during many intervals of rapid climate warming and, have been postulated to be the cause of this massive release of isotopically light carbon. In this contribution, we will present new sedimentological organic geochemical and compound specific carbon isotope data from different Early Aptian sections exhibiting a negative isotopic carbon spike, and discuss possible origins of this negative carbon isotope excursion.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting