HR: 17:45h
AN: PP34B-08 INVITED     [Abstracts]
TI: Final closure of the Panamaian Isthmus and the onset of northern hemisphere glaciation
AU: * Sarnthein, M
EM: ms@gpi.uni-kiel.de
AF: Institute for Geosciences, Kiel University, Olshausenstr. 40, Kiel, 24098 Germany
AU: Bartoli, G
EM: gb@gpi.uni-kiel.de
AF: Institute for Geosciences, Kiel University, Olshausenstr. 40, Kiel, 24098 Germany
AU: Weinelt, M
EM: mw@gpi.uni-kiel.de
AF: Institute for Geosciences, Kiel University, Olshausenstr. 40, Kiel, 24098 Germany
AU: Erlenkeuser, H
EM: HErlenkeuser@leibniz.uni-kiel.de
AF: Leibniz Laboratory, Kiel University, Olshausenstr. 40, Kiel, DEU 24098 Germany
AU: Garbe-Schoenberg, D
EM: dgs@gpi.uni-kiel.de
AF: Institute for Geosciences, Kiel University, Olshausenstr. 40, Kiel, 24098 Germany
AU: Lea, D W
EM: lea@magic.geol.ucsb.edu
AF: Dept. of Geological Sciences, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AB: The Greenland ice sheet forms a key factor controlling the Quaternary-style glacial scenario. However, origin and mechanisms of major Arctic glaciation starting at 3.15 Ma and culminating at 2.74 Ma have remained controversial. For this phase of intense cooling Ravelo et al. (2004) proposed a complex gradual forcing mechanism. In contrast, our new submillennial-scale paleoceanographic records from the Pliocene North Atlantic suggest a far more precise timing and forcing for the initiation of northern hemisphere glaciation (NHG), since it was linked to a 2-3 /degC surface water warming during warm stages from 2.95 to 2.82 Ma (until glacial stage G10). These records support previous models (Haug and Tiedemann, 1998) claiming that the final closure of the Panama Isthmus (3.0 - ~2.5 Ma; Groeneveld, 2005) induced an increased poleward salt and heat transport. Associated strengthening of North Atlantic thermohaline circulation and in turn, an intensified moisture supply to northern high latitudes resulted in the build-up of NHG, finally culminating in the great, irreversible climate crash at glacial stage G6 (2.74 Ma). In summary, we see a two-step threshold mechanism that marked the onset of NHG with glacial-to-interglacial cycles quasi-persistent until today. G r o e n e v e l d, J., The final closure of the Central American Seaway. PhD Thesis Kiel, 2005. H a u g, G. and T i e d e m a n n , R., 1 9 9 8. Nature 393, 676-678. R a v e l o , A.C., e t a l ., 2004. Nature 429, 263-267.
DE: 1105 Quaternary geochronology
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1626 Global climate models (3337, 4928)
DE: 4954 Sea surface temperature
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005