HR: 1330h
AN: PP42A-0857    [PDF]
TI: A Speleothem Climate Record of the Last Deglaciation From Southwestern Oregon
AU: * Vacco, D A
EM: dvacco@geosc.psu.edu
AF: Department of Geosciences, Pennsylvania State University 441 Deike building, State College, PA 16801 United States
AU: Clark, P U
EM: clarkp@onid.orst.edu
AF: Department of Geosciences, Oregon State University 104 Wilkinson Hall, Corvallis, OR 97331 United States
AU: Mix, A C
EM: amix@coas.oregonstate.edu
AF: College of Ocean and Atmospheric Sciences, Oregon State University 104 Ocean. Admin. Bldg., Corvallis, OR 97331 United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AU: Edwards, R L
EM: edwar001@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AB: We measured oxygen (d18O) and carbon (d13C) isotope values along the growth axis of a stalagmite from Oregon Caves National Monument (OCNM), Oregon, in order to construct a climate record covering the last deglaciation. We use nine uranium-series dates to construct an age model for our record from 13.3 ka to 9.7 ka; corresponding stalagmite growth rates are 0.8 - 2.0 mm/100 yrs. A numerical evaluation established that variations in atmospheric temperature are the dominant process controlling d18O variations in the speleothem. Lighter d18O values from 12.9 to 11. 7 ka indicate colder atmospheric temperatures in the Pacific Northwest (PNW). Rapid atmospheric warming occurred at 11. 7 ka, but d18O variations through the remainder of our record indicate significant centennial-scale variability. Local vegetation records indicate that the ratio of C3/C4 type plants was constant through the last deglaciation. Hence, we infer that d13C variations in OCNM speleothems were dominantly controlled by changes in the amount of biomass over the caves. Specifically, the d13C record from OCNM suggests that biomass increased over the caves through the last deglaciation, with a stall in the increase of biomass occurring between 12.5 and 11.3 ka. Similarities between the timing of events in the OCNM d18O record, SST records from the northeastern Pacific Ocean, a d18O record from Hulu Cave, China, and the GISP2 ice core record indicate synchronous hemispheric climate changes during the last deglaciation.
DE: 3344 Paleoclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting