ELEMENT AND STABLE ISOTOPE AQUEOUS GEOCHEMISTRY FROM BAYSUN TAU, UZBEKISTAN–TRACING THE SOURCE OF THE DRIPWATER

Palaeoclimatic information from Central Asia is sparse. The geographical setting in the semi-arid high altitude mountains of Central Asia makes its karst regions hardly accessible. In a suitability study for palaeoclimatic work in the region, we analyzed stable isotopic composition (δ18O and δD) and major element concentration in water samples collected in August 2012 in the Baysun Tau mountains, SE Uzbekistan. δ18O and δD of snow and karst water fall on the Eastern Meteoric Water Line, while rainwater show strong evaporation effects. These preliminary results indicate a dominant moisture source in the arid continental regions west of the Baysun Tau (arid Uzbekistan and Afghanistan), and snowmelt as the major source for infiltration. Dripwater element ratios seem to change in accordance with drip rates, suggesting prior calcite precipitation in the epikarst above the studied cave. We speculate that isotope profiles from stalagmites should be biased towards the wet winter season. We advise robust monitoring of dripwater chemistry as an essential means that allows for accurate interpretation of stalagmite paleoenvironmental records.