The Application of a Volcanic Facies Model to an Andesitic Stratovolcano Hosted Geothermal System at Wayang Windu, Java, Indonesia

Abstract

The surface alteration between the Te Kopia and Orakeikorako geothermal areas the thermal evolution of these systems. This study correlates and describes the distribution of active and fossil hydrothermal activity along the Paeroa Fault and the uplifted Paeroa Block between the two thermal areas. Alteration styles found, consist of acid alteration by heated waters, silicic and near neutral alteration by deep chloride waters, and acid overprinting of earlier neutral alteration. Previously unreported sinters and hydrothermal breccias are located between the two active areas showing that thermal activity was more extensiveprior to 22.7 Ka. The reduction in thermal activity was preceded by a drop in the water table which may have resulted from self sealing, or migration of the thermal areas controlled by the Paeroa Fault.