Quaternary Paleoclimate Record from Tropical South America: Lake Titicaca

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Abstract ATM-9616972 Baker, Paul A. Duke University ATM-9708257 Dunbar, Robert B. William Marsh Rice University ATM-9708256 Fritz, Sherilyn C. LeHigh University ATM-9708258 Seltzer, Geoffrey Syracuse University Title: Quaternary Paleoclimate Record from SOuth America: Lake Titicaca A long and continuous paleoclimate record from tropical South America is needed to answer several persistent and important questions. This award supports the recovery of such a record by coring the deep basin of Lake Titicaca on the northern Altiplano of Peru and Bolivia. Through the preliminary analysis of a series of short, mini-piston cores, it is demonstrated that the sediments of the lake are suitable for climatic reconstruction. Also, high- solution seismic reflection profiling has shown that there are many excellent localities for siting much longer piston cores and for obtaining even older sediments via offset coring. Previous studies revealed large-amplitude fluctuations of lake level in the Holocene and Pleistocene, implying that effective moisture (and probably temperature) has likewise varied drastically. Siting of a series of long cores will be aided by medium-resolution, deeper penetration seismic reflection profiling with uniboom and water gun sound sources. The cores will be subsequently analyzed for chronology (AMS radiocarbon), sedimentology (X-ray diffraction and optical petrography), physical properties (porosity, density, magnetic susceptibiity), geochemistry (stable isotopic analysis and minor-element chemistry of ostracodes; stable isotopic analysis of organic carbon and cellulose; determination of organic and inorganic phosphorous, and biogenic silica; strontium isotopic analysis of ostracodes) and paleobiota (ostracode and diatom species compositions), This record will allow us to examine in detail the timing and mechanisms of tropical forcing of high- latitude climate (and vice versa), as well as the linkage between the climate of the Altiplano and the Amazon basin