The Structure and Origin of the South Kambalny Central Thermal Field, Kamchatka

Abstract

Integrated geological and structural geophysical studies have shown that the South Kambalny Central Thermal Field was formed in the crater of a cone belonging to a Pliocene–Pleistocene volcano at the Kambalny Range. A geothermal reservoir has been identified beneath the thermal field; this is a rock volume rich in aqueous and steam-gas fluids. The center of the thermal field contains a zone of less dense rocks which controls the flow of ascending alkaline metal-bearing brine and is interpreted as the vent of a crater. We studied the structure of a sequence of hydrothermal clays and argillized, zeolitized, and carbonized bedrock basaltic andesites that form the base of the clay sequence. We provide a detailed characterization of newly formed mineral compounds in deposits of three types: siliceous sediments occurring along the periphery of the thermal field; carbonate concretions at the base of the hydrothermal clay sequence; and altered basaltic andesites. We have provided a substantiation: the hydrothermal mineralization, including ore mineralization, is an indicator of the influence of the deep-seated alkaline metal-bearing fluid on the zone of vapor-rich hydrothermal fluids. It is hypothesized that the sources of ore compounds, as well as of nitrogen and phosphorus, may be due to basite intrusions identified in the southern group of thermal fields in the Kambalny volcanic range.