ON THE CONDITIONS OF WATER AND HEAT FEEDING OF THE PAUZHETKA HYDROTHERMAL SYSTEM (SOUTH KANCHATKA, USSR)

Abstract

The Pauzhetka hydrothermal system is located in a volcano-tectonic depression near active volcanic centers. Temperatures at depths of 300-800 m are 180-210 C. The natural discharge of the hydrothermal system includes the discharge of the Pauzhetka springs and a concealed discharge in the bed of the Pauzhetka River (95 kg/s) and the steam discharge in the Kambalny Ridge (15 kg/s). Only the upper part of geothermal reservoir was penetrated by drillholes (up to 1200 m), therefore they have used a mathematical modeling to assess the conditions of water and heat feeding of the hydrothermal system. The hydrothermal system belongs to a linear fracturing zone of NW trend, therefore the two-dimensional model was used in the calculations. It has been defined that (1) the source of heating is a magma chamber located at a shallow depth; (2) the heat and mass transfer in the geothermal reservoir is defined by free and forced hydraulic convection, (3) the conductivity coefficient of a linear fracturing zone is 400-600 m{sup 2}/day, its width is 2 km and length is 10 km, and (4) the water feeding is defined by infiltration in the recharge area. Calculations of temperature and velocity fields agree with real data obtained in the Pauzhtka geothermal area, therefore they may be a base for assessment of water and heat feeding of the hydrothermal system. In accordance with these assessments, the main part of water resources is derived from infiltration. Heat feeding may be maintained by cooling of the magma chamber with a volume of 18 km{sup 3} that is in accordance with the volume of Holocene igneous rocks