Volcanic, climatic and geodynamic factors controlling the evolution of Lake Van (Turkey)

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The goal of the project is a high-resolution chronology of a ca. 220 m long and ca. 600 ka old sediment core drilled in the alkalic Lake Van (Turkey) sediments, containing ca. 500 interbedded tephra layers. Tephra layers of primary origin will be scrutinized lithologically and analyzed by EMP and XRF prior to selection of suitable samples containing sufficient anorthoclase for 40Ar/39Ar and zircon/chevkinite phenocrysts for (U-Th)/He single crystal dating. The robust chronological framework will allow calibrating several types of paleoclimate and geodynamic proxies. A second goal concerns reconstruction of magnitude, age, frequency and origin (climate vs. geodynamics) of major lake level changes of Lake Van based on an analysis of the lithology and age of the main seismic reflectors. Preliminary studies suggest that especially the older reflectors (ca. 200-600 ka) are mainly syn-ignimbrite turbidites generated during voluminous ignimbrite eruptions from adjacent Nemrut volcano. A third objective concerns the chemical-mineralogical-temporal evolution of the two main source volcanoes Nemrut and Süphan and the prediction of future explosive eruptions and associated hazards. The high-resolution temporal framework will also allow to more precisely determine the transition from freshwater to alkaline lake condition and therefore the timing of the growth of Nemrut volcano probably the central factor leading to damming and isolation of Van basin.