HR: 0800h
AN: PP41C-0685    [Abstracts]
TI: Climatic Shifts and Geomagnetic Excursions
AU: * Wetter, L
EM: wetter@geology.ucdavis.edu
AF: Department of Geology, UC Davis, One Shields Avenue, Davis, CA 95616, United States
AU: Acton, G
EM: acton@geology.ucdavis.edu
AF: Department of Geology, UC Davis, One Shields Avenue, Davis, CA 95616, United States
AB: Studies arguing for a link between geomagnetic field variability and climate change have been inconclusive due to a variety of reasons including low-resolution paleomagnetic or climatic records, age uncertainties, and strong lithologic biases in relative paleointensity records. We present an improved chronology of a high-resolution paleomagnetic record recovered from Ocean Drilling Program Site 1061 (Leg 172) on the Blake Outer Ridge (BOR) in the western North Atlantic Ocean in order to test for such a relationship. Sediments from the BOR are established recorders of climate change and have the high sedimentation rate (10-25 cm/k.y.) necessary to document geomagnetic variability on a scale that allows for the accurate comparison of timing with proxies of climate change. Additionally, the sediments contain a large number of excursions that we use here to resolve short-term geomagnetic variations. This is important, as our correlation to climatic change is not dependent on relative paleointensities alone. Our age model refined the existing astronomically-tuned model for the area via high-resolution stable isotope measurements over intervals containing excursions, which were then correlated to the global isotopic stack of Lisiecki and Raymo [2005]. Using the resulting complete and continuous well-dated record of geomagnetic field variability we found excursions to occur predominantly after or synchronous with large isotopic changes and to occur preferentially within interglacials.
DE: 1513 Geomagnetic excursions
DE: 1521 Paleointensity
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4940 Isotopic stage
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting