HR: 0800h
AN: PP41C-0675    [Abstracts]
TI: Decadal Scale Variability in sub Antarctic Surface and Intermediate Water Properties Across the Laschamp Geomagnetic Excursion at ODP Site 1233
AU: * Foerde, A
EM: anneelin@gmail.com
AF: Department of Earth Science, University of Bergen, Allegaten 41, Bergen, N-5007, Norway
AU: Kleiven, H F
EM: kikki@uib.no
AF: Department of Earth Science, University of Bergen, Allegaten 41, Bergen, N-5007, Norway
AU: Kleiven, H F
EM: kikki@uib.no
AF: Bjerknes Centre for Climate Research, University of Bergen, Allegaten 55, Bergen, 5007, Norway
AU: Ninnemann, U S
EM: ulysses@uib.no
AF: Department of Earth Science, University of Bergen, Allegaten 41, Bergen, N-5007, Norway
AU: Ninnemann, U S
EM: ulysses@uib.no
AF: Bjerknes Centre for Climate Research, University of Bergen, Allegaten 55, Bergen, 5007, Norway
AB: Here we report decadally resolved planktonic and benthic foraminiferal oxygen isotopic proxy reconstructions of surface and intermediate ocean properties across the Laschamp geomagnetic excursion (32-43 ka) from Ocean Drilling Program (ODP) Site 1233 (41°00'S, 74°27'W, 838m) on the Chilean continental margin. The sedimentation rates at this site spanning MIS 3 (~2.2 m/kyr) allow us to nominally achieve a temporal resolution of less than 20 years with 4cm sample spacing. Site 1233 is located on the northern margin of the Antarctic Circumpolar Current (ACC) and the seafloor lies in the core of Antarctic Intermediate Water (AAIW). Thus the site is ideally situated to reconstruct both near surface and AAIW variability in the high southern latitudes. The clearly defined Laschamp event in our core provides a stratigraphic reference for comparing the relative rate and timing of abrupt changes observed at our site to those observed globally. Our initial foraminiferal oxygen isotopic results show that variations in intermediate ocean properties and climate of the southeast Pacific closely align with those recorded in the EPICA ice core from Dronning Maud Land on millennial and even centennial timescales. The broad coherence of the observed Antarctic signal supports the concept of hemispheric thermal asynchrony on millennial timescales. The extension of this climate signal into the intermediate ocean demonstrates that AAIW is extremely sensitive and responds rapidly to climate variability in its source region on a broad spectrum of timescales. Using the Laschamp as a reference point, we compare the timing of our AAIW changes to those in other regions to evaluate the importance of AAIW in propagating climate signals.
DE: 3036 Ocean drilling
DE: 4870 Stable isotopes (0454, 1041)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4954 Sea surface temperature
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting