Millennial environment chronology in Eastern Turkey calculated by the composition of laminated sediments from Van and Erchek adjacent Lakes

Abstract

Turkish lakes Van and its satellite Erchek are located in a climate-sensitive area between the seas Black, Caspian and Mediterranean at the intersection of the atmospheric South-West flow and the Northern branch of the subtropical high-pressure belt. It is shown that the sediments of the adjacent lakes Van and Erchek at a distance of 20 km from each other, synchronously reacted to regional changes in the environment. This work contains high-resolution geochemical data on bottom sediments, which allowed converting them into time series of paleotemperature and lake level fluctuations on an annual-decadal scale. Physical and chemical conditions in model equilibrium systems (solid phase + water + gas) in the real range of external hydro-climatic factors were estimated based on the mineral composition of lake sediments of clay-carbonate type. To create a timescale, we used visual calculations of annual rhythms, as well as seasonal fluctuations in the content of elements. The time series of elements were synchronized with recent changes in weather conditions and with fluctuations in lake levels. So geochemical series calibrated on hydro-meteorological data were transformed by multiple regression approach into numerical reconstructions of natural parameters on a time scale. As a result, quantitative reconstructions of regional temperature were calculated: for Lake Van 1300 and Erchek - 840 years ago, as well as Van level 840 yrs.