PROCEEDINGS, 45th Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 10-12, 2020 SGP-TR-216 The Role of the Artesian Hydrothermal Systems in the Formation of Large-volume Acidic Rocks in the Geothermal Regions of Kamchatka Vladimir I. Belousov1, Irina V. Belousova1, and Olga R. Khubaeva1,2 1Russia, Petropavlovsk-Kamchatsky, Boulevard Piipa 9, Institute of Volcanology and Seismology,
[email protected] 2Russia, Moscow, B. Gruzinskaya Street 10, b.1, Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences Keywords: large-volume acidic rocks, volcanic complex, “supervolcano”, geothermal area, long-lived volcanic centers, volcano- tectonic depression, hydrothermal metamorphism, cap rock, ignimbrites, glacier. ABSTRACT The formation of large volumes of rocks of acid volcanism is an important process in the geothermal regions of Kamchatka. Currently, the hypothesis of a catastrophic eruption of a "supervolcano" in the Banno-Paratunsky geothermal area has become widespread. The basis for this concept is some data on the formation of a thick stratum of acidic and ultra-acidic rocks, which is known as the Karymshinsky volcanic complex. It is located in the volcano-tectonic depression. Caldera not found. There are no signs of the movement of acidic products of a powerful explosion (~ 275 km3). It is assumed, that the internal energy of acidic magmas in this region is insufficient for the formation of such a mass of eruption products. In this regard, it is assumed that this concept is not sufficiently substantiated. Recently, evidence has appeared that large-scale ignimbrites and rhyolites are formed from metamorphic rocks. In this regard, we propose a new concept of their formation, based on the role of hydrothermal metamorphism in the bowels of artesian hydrothermal systems.