Evaluation of radioactivity of the rocks in the foothills of the main caucasian range in the territory of Kakheti region (East Georgia-Country)

This study investigates distribution of natural and technogenic radionuclides in rock samples in the eastern part of Kakheti region. The radioactivity of rocks in this region has not been investigated. 20 samples of rocks of various types - igneous, sedimentary and metamorphic were investigated with the gamma-spectroscopic method applied. Up to 21 naturally occurring radionuclides and 1 technogenic radionuclide have been identified in samples. Average activity concentration of Th-232 family radionuclides varied from 0.61 to 98.6 Bq/kg, U-238 family - from 9.1 to 77.0 Bq/kg, U-235 family - from 0.10 to 3.5 Bq/kg. The highest activity concentration was observed for K-40 (maximal value of 1475 Bq/kg). Activity of technogenic radionuclide Cs-137 varied from 0.10 to 1.2 Bq/kg. There are some marked features in radionuclides distribution depending, in particular, on rock type, tectonic zone. Some radionuclide activity ratios have been considered, in particular, U-238/U-235, U-238/Th-232, Ra-226/U-238 and Pb-210/Ra-226. These ratios allow to estimate condition of system (closed or opened) and to receive a certain notion about character of relevant geochemical processes. Comparison was carried out with existing data in the literature. (author)