Patterns in the transformation of the composition and properties of volcanogenic rocks in hydrothermal-magmatic systems of the Kuril-Kamchatka island arc

Abstract

Hydrothermal-magmatic systems of the Kuril-Kamchatka island arc were formed in Neogene-Quaternary volcanic rocks. Acting on host rocks, thermal waters induced their alteration and transformation into hydrothermal-metasomatic rocks, such as propylites, secondary quartzites, zeolitic rocks, argillic rocks, opalites, quartz-adularia metasomatites, etc. The dynamics of changes in rock properties during the hydrothermal process depends on a number of factors, including the features of primary rocks, temperature, pressure and composition of thermal fluids, fluid phase, fluid pH, and duration of fluid-rock interaction. Deep high-temperature fluids cause consolidation and hardening of the rocks, an increase in deformational properties, and a decrease in porosity and permeability, regardless of fluid composition. The chemical composition and acidity-alkalinity of thermal fluids have a significant influence on the alteration of rock properties during low-temperature hydrothermal processes.