TRANSFORMATION OF THE INITIAL ISOTOPIC COMPOSITION OF PRECIPITATION IN CAVES OF THE SOUTH-WESTERN CAUCASUS

摘要

The paper presents preliminary results and interpretation from an ongoing research project in the Novy Afon and Abrskil caves of Abkhazia. The research have demonstrated that δ18O and δD analyses of drip and ground waters in two caves in the South-Western Caucasian region allows to better understand interaction between isotopic composition of precipitation, soil, and vadose zone. Drip and ground water samples from the caves were compared with the present-day Global (GMWL) and the Local Meteoric Water Lines (LMWL). They fall along the GMWL and LMWL and are tied by equation δD = 5.74δ18O - 6.98 (r2 = 0.94). Drip water isotopic composition is similar to that from lakes and pools. The incline of δ18O - δD line differs from GMWL and LMWL. It reflects a possible result from secondary condensation and evaporation and water-rock interaction, and depends on the climate aridity level.