Environmental response to climatic and volcanic events in NE Anatolia during the last 20,000 years based on annually laminated sediments from Lake Van

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Tephra layers drilled in 400 m-deep Lake Van (Anatolia) in 2004 will be studied structurally, texturally and compositionally for correlation between drill sites and with volcanic deposits on land. Analysis of equivalent deposits on the historically active caldera volcano Nemrut, the major supplier of tephra, will allow reconstructing larger volcanic events (Plinian fallout, pyroclastic flows and flank collapses), magma evolution and environmental impacts such as tsunamis. Interaction of volcanic glass with alkaline pore solutions in lake sediments is likely to have released biologically relevant elements. The analytical focus is on Iaser-ICP-MS composition of glass shards and phenocrysts and 40Ar/39Ar single crystal dating. Reconstruction of mass transfer processes during major volcanic events adjacent to the lake will aid volcanic hazard and risk assessment at Lake Van. High-resolution pollen analyses based on the annually laminated lacustrine sediments should reflect the impact of volcanic events on paleoenvironment. The comparison between volcanic and climatically induced vegetation changes will be analyzed. Short-term effects of volcanic eruptions on vegetation can only be traced by a high-resolution stratigraphy. The varved sediment record of lake Van is an excellent archive for this approach.