HELIUM ISOTOPES IN THE UNDERGROUND SPRINGS OF EAST TUVA

Abstract

East Tuva, one of the most seismoactive zones of the Altai–Sayan region, is located at its eastern flank and adjoins riftogenic structures of the southwestern termination of the Baikal rift zone (BRZ). East Tuva incorporates a volcanic area including one of the largest recent lava fields (East Tuva lava highland) in Central Asia and extended valley lava flows. This zone is considered volcanically active and hazardous. The lava field is controlled by the NNE-oriented fault system, which also governed the formation of the southern present-day Bilin–Busiingol graben. The area of East Tuva and adjacent Mongolia is characterized by a sharp change in the stress-strain state of the lithosphere. Numerous thermal veins and some geothermal estimates of heat flow attest to high temperatures in the Earth’s interior in this area.