HR: 09:15h
AN: PP31C-06    [Abstracts]
TI: High-Resolution South Pole Dust Log and Evidence of Low Sulfur Volcanic Eruptions
AU: * Rohde, R A
EM: bobbyr@berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720 United States
AU: Bramall, N
EM: bramall@berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720 United States
AU: Bay, R C
EM: bay@cletus.physics.berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720 United States
AU: Price, P B
EM: bprice@berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720 United States
AB: As part of the commissioning of the ICECUBE Neutrino Observatory, an improved dust logger was deployed to make sub-centimeter scale measurements of ice optical properties most of the way down a 2400m South Pole borehole. These measurements, covering approximately 70,000 years, provide the highest resolution record of dust accumulation now available and also record a number of distinct volcanic ash horizons. During the last glacial period, subtle variations in the dust accumulation at South Pole appear well correlated to rapid climate changes in Greenland (i.e. Dansgaard-Oeschger events). With improved timing information, high-resolution records such as these should be able to answer the question of whether climate changes in the South typically precede or follow climate changes in the North. The most likely source of high precision timing information will be the identification of synchronous volcanic markers at both North and South poles. Existing and forthcoming work relying on sulfate concentrations has already allowed some matching volcanic horizons to be found at both poles. However, the dust logger, with its ability to detect ash layers so faint as to escape unaided recognition, opens up a complementary method in the search for correlated volcanic events. One of the most remarkable findings from this new log is the presence of volcanic events which appear to have simultaneously deposited ash at South Pole and GISP2 (prior work by us), but for which there are no reports of a global volcanic sulfate spike. This suggests that it is possible for a volcanic eruption to be sufficiently explosive as to globally distribute ash without generating the type of sulfate pulse relied upon in most previous studies of volcanism in ice cores. If such apparently contemporaneous ash layers truly come from a single eruption, then we would have no choice but to conclude that studies of volcanism relying on sulfate alone are an inherently incomplete record of major eruptive events.
DE: 0724 Ice cores (4932)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4938 Interhemispheric phasing
DE: 8408 Volcano/climate interactions (1605, 3309)
DE: 8428 Explosive volcanism
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005