HR: 1340h
AN: PP13A-0583    [Abstracts]
TI: Speleothem Records of Precipitation in the West Pacific Warm Pool
AU: * Cobb, K M
EM: kcobb@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, MC 0340 Georgia Inst. of Technology, 311 Ferst Dr, Atlanta, GA 30332 United States
AU: Adkins, J F
EM: jess@gps.caltech.edu
AF: Dept. of Earth and Planetary Sciences Caltech, MC 100-23, 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: The El Nino-Southern Oscillation demonstrates that changes in the strength and location of deep convection in the West Pacific Warm Pool (WPWP) have a large impact on global climate patterns. However, the relationship between WPWP convection and global climate change on lower frequency timescales is poorly constrained by available proxy records. A recent field expedition to Gunung Buda National Park, located in Northern Borneo (4§N, 114§W), yielded dozens of stalagmites from a variety of caves. The stalagmites range in length from 5cm to 2m in length and several thousand years to $>$700,000 years in age, as determined by multi-collector ICPMS U/Th ages, with many samples capturing Marine Isotope Stage 3, the deglaciation, and the Holocene. Preliminary data from a sample that spans the last 26ky includes d18O and Mg/Ca values that capture the transition from glacial to Holocene conditions, implying drier LGM conditions relative to present. A down-core greyscale profile from the same stalagmite demonstrates that climatic changes may also be recorded in the speleothem's optical properties. High-resolution, paired optical (fluorescence and reflected light) and geochemical (Mg/Ca, Sr/Ca, and d18O) measurements help to build an interpretive framework for the optical variability and demonstrate the potential of using fast, non-destructive optical techniques for climate reconstruction in the Gunung Buda stalagmites. Rainwater and cave dripwater samples collected at Gunung Buda and nearby Mulu National Park are used to constrain spatial and temporal variability in the relationship between climate variability, cave dripwater chemistry, and stalagmite geochemistry. In addition to this rainwater-dripwater-stalagmite calibration effort, we are constructing an ultra-high-resolution geochemical timeseries of the upper-most section of fast-growing stalagmites to calibrate against local and regional-scale instrumental records of climate variability.
DE: 4860 Radioactivity and radioisotopes
DE: 4870 Stable isotopes
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 1833 Hydroclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting