The Quaternary Record of Lake-Level Oscillation and Climate Change: Lake Issyk-Kul, Kyrgyzstan, Central Asia

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Abstract ATM-9632967 Rasmussen, Kenneth A. Macintyre, Ian G. Smithsonian Institution Title: The Quaternary Record of Lake-Level Oscillation and Climate Change: Lake Issyk-Kul, Kyrgyzstan, Central Asia Lake Issyk-Kui in the former Soviet Republic of Kyrgyzstan is the fifth deepest lake in the world (668 meters). Issyk-Kul is located 1600m above sea level in the Asian landmass, and is positioned between the winter Siberian High and the summer Southwest Indian Low-even subtle changes in moisture and/or temperature regime due to climate shifts in the position or intensity of these major atmospheric elements should effect changes in lake-level Issyk-Kul is a closed-basin lake with abundant carbonate sediments and a rich natural history of large-scale, and ongoing lake-level change. Modern lake level has fallen 3 meters in the last 70 years and evidence suggests even larger oscillations long before any possible human intervention. Preliminary fieldwork revealed that paleo- shorelines are recorded in coastal hardgrounds of inorganic and microbialitic origin- these provide a dateable proxy for Late Holocene lake level positions. This award supports a investigation of: (1) nearshore carbonates and Late Holocene beach deposits, and (2) the deep-basin sedimentary and paleolimnological record. Paleoenivronmental significance of the relic microbialites will be established through modern analogues. Origin, growth, and recent environmental history of the living and relic microbialites will be established through petrographic techniques, mineralogic analysis of cements to detect salinity shifts, and preliminary stable isotopes analysis of calcite cements to assess their utility as proxies for hydrologic regime.