HR: 1340h
AN: U13B-1158    [Abstracts]
TI: The Malili Lakes, Indonesia: Potential Archives of Long Records of Terrestrial Paleoclimate from the Equatorial Western Pacific
AU: * Russell, J M
EM: James_Russell@Brown.edu
AF: Dept. of Geological Sciences, Brown University 324 Brook St., Providence, RI 02912, United States
AU: Bijaksana, S
EM: satria@fi.itb.ac.id
AF: Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesa 10, Bandung, 40132, Indonesia
AU: Tierney, J
EM: Jessica_Tierney@Brown.edu
AF: Dept. of Geological Sciences, Brown University 324 Brook St., Providence, RI 02912, United States
AU: Wattrus, N
EM: nwattrus@d.umn.edu
AF: Large Lakes Observatory, University of Minnesota Duluth 10 University Drive, Duluth, MN 55812, United States
AB: The tropical western Pacific Ocean exerts a dominant influence on the Earth's atmospheric heat and moisture budgets. Continental drilling of lake deposits through DOSECC and ICDP has begun to provide critical new information on the Plio-Pleistocene history of tropical continental climate, yet no potential drilling sites have been identified in the tropical western Pacific. Here we report results from the first seismic reflection studies ever conducted on large lakes in Indonesia that highlight the potential of Lake Towuti, South Sulawesi, for obtaining long terrestrial records of western Pacific climate.
We have collected nearly 500 km of high-resolution seismic reflection (CHIRP) data from Lakes Matano (164 km2, 590 m deep) and Towuti (560 km2, 203 m deep), two of the Malili Lakes in central Sulawesi. These tectonic lakes formed about 2 Myr BP, and thus have the potential to provide long records of Indonesian climate. Seismic stratigraphic analyses of sediments from Lake Matano document numerous slump and slide deposits, the proximity of which to Matano's deepest structural troughs as well as gravity core data suggests that sediments accumulating in Matano's deep basins represents the distal end of catastrophic sedimentary processes. Although seismic data from shallow sites indicate the presence of unconformities related to climate-driven water level changes in Matano, attesting to Lake Matano's climate sensitivity, sedimentation in Matano appears to be too complex to warrant scientific drilling.
On the other hand, well-stratified sediments are present across much of Lake Towuti. The deepest basins in Lake Towuti are far removed from slump deposits and fluvio-deltaic inputs, and contain highly stratified sediments ideal for paleoenvironmental analysis. A series of high-amplitude reflectors in the upper 110 meters of sediment (our maximum penetration with the CHIRP) can be traced across much of the Towuti basin. Acoustic properties of these reflectors, together with channel features and other sequences, suggest substantial changes in Towuti's water level in response to Pleistocene environmental changes. Lithologic, geophysical, and geochemical analyses of sediment cores from Towuti show that the sediments contain a wealth of climate indicators that may be used to reconstruct continental climate in the western Pacific. In short, we suggest that Lake Towuti has the potential to provide long, powerful new records of Pleistocene climate from the equatorial western Pacific.
DE: 0935 Seismic methods (3025, 7294)
DE: 1845 Limnology (0458, 4239, 4942)
DE: 4914 Continental climate records
DE: 4922 El Nino (4522)
SC: Union [U]
MN: 2007 Fall Meeting