COASTAL THERMAL SPRINGS IN THE CENTRAL PART OF ITURUP ISLAND: MACRO- AND MICROELEMENT COMPOSITION
Based on the results of expeditionary studies (July 2021), geochemical features of thermal waters (natural manifestations and borehole waters) discharging near or directly on the Sea of Okhotsk and Pacific coasts of the central part of Iturup Island were considered: Reidovskie, Lososevye, Cape Konakov, Goryachie Klyuchi, Dachnye, water-recreational complex «Vannochki». The springs (with the exception of Lososevye) belong to subneutral Cl(Cl-HCO<sub>3</sub>)-Na waters with salinity less than 10 g/l. The Lososevye springs are of the weakly acidic HCO<sub>3</sub>-SO<sub>4</sub>-Ca-Na type with salinity of 3 g/l. The spontaneous gas is dominated by CO<sub>2</sub> (Dachnye and Vannochki), N<sub>2</sub> (Reidovskie and Cape Konakov) and CH<sub>4</sub> (Goryachie Klyuchi). Against the background of a general extremely low content of microelements, thermal waters are enriched with boron and lithium. The springs are characterized by small (0.1 l/s) to insignificant (0.02-0.05 l/s) flow rates, while wells drilled nearby uncover horizons of pressurized waters.