| Title | New Data on Structure of Pauzhetsky Geothermal Deposit (South Kamchatka, Russia) |
|---|---|
| Authors | Sergey O. FEOFILAKTOV, Sergey N. RYCHAGOV, Ilyas F. ABKADYROV, Yury Yu. BUKATOV, Ivan A. NUZHDAEV |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | water-dominated geothermal deposit, block structure, aquifer, gravity anomaly, specific resistance, microseismic sounding, magnetometer survey |
| Abstract | The study of Pauzhetsky hydrothermal system in the 1959-60s triggered the development of geothermal power industry in Kamchatka. In 1966-67s, Pauzhetsky experimental-industrial geothermal power plant that was first both in USSR and Russia was commissioned and it has been working in a sustainable way up to now providing electric power to a number of settlements and fish factories of Kamchatka Krai's Ust-Bolsheretsk district. However, an increased power consumption from population and industrial entities of the district has recently experienced a lack of power supply from Pauzhetsky Geothermal Power Plant which is also caused by reduction of performance values of operational areas at the deposit. In our opinion, the latter reason can be explained by an insufficient level of study of the hydrothermal system in terms of geology. Exploitation of the deposit is based on the use of the geological-hydrogeological model built at the early stage of study of the hydrothermal system (Pauzhetskiye goriachiye vodi na Kamchatke, (Pauzhetka Hot Springs) 1965). According to this model, high temperature hydrothermal waters flow via two aquifers flat-dipping from the side of resurgent block of the Kambalny volcanic ridge in the interior of which cooling magma chambers are hosted. Thus, it is assumed that a heat source for the hydrothermal system is an induced one, and the hydrothermal outflows are discharged through subvertical faults and in the valley of the Pauzhetka river (an upper-Quaternary fault trough of the same name). Additional topical research and detailed studies of separate sections of the deposit helped to identify uplifted tectonic-magmatic blocks within which hydrothermal waters actively circulate and the waters of lower and upper aquifers mix (Structura gydrotermalnoy sistemi, (Structure of a Hydrothermal System) 1993). The acquired data suggest there is a complex geological block structure of Pauzhetsky geothermal deposit which governs the ascent and discharge of hydrothermal gas-vapour outflows. In this respect, the resolution of the heat source issue for the hydrothermal system is especially relevant. In recent years, the South-Kamchatka-Kuril surveying company of Institute of Volcanology and Seismology FED RAS has been conducting integrated geological-geophysical research at Pauzhetsky geothermal deposit. New data on structure of the upper-confining stratum and upper aquifer have been acquired by means of modern geophysical techniques (high precision gravimetry, magnetometry, resistivity prospecting, microseismic sounding), structure of uplifted "hot" tectonic blocks in the area of Verkhne (Upper)-Pauzhetsky and East-Pauzhetsky thermal fields has been updated. A large subvertical section of decompressed rocks has been identified in the central part of the deposit which can be interpreted as a zone of an ascending deep gas-hydrothermal fluid and, consequently, it is assumed that this zone is connected with the source of a geothermal heat medium located within the structure of Pauzhetsky hydrothermal system. This work has been carried out with a financial support from the Russian Foundation for Fundamental Research (Projects 13-05-00262, 14-05-31158) and Far-Eastern Division of the Russian Academy of Science. |