Indication of Intrusive Body in Wapsalit Geothermal Area, Buru Island, Indonesia

Abstract

Wapsalit geothermal area is a non-volcanic geothermal area. This area is covered by low to medium grade metamorphic rocks, Quarternary sediment and Quarternary surface deposits.
Gravity data show a high anomaly at the center and southwestern flank of the area, which is coincident with the thermal features. The anomaly is interpreted as an igneous minor intrusion (laccolith/sill?) which is possibly the heat source for the Wapsalit geothermal system.
Thermal features of the area have relatively high temperature ranging from 60.5 to 101.3°C, neutral pH, and total flow rate about 3 l/sec. Silica geothermometry shows a high enthalpy in the area. This indicates a possibility of magmatic activity beneath the area. No geological evidence for igneous rock is found on the surface, however gravity and geothermometry data indicate the existence of young minor intrusion as the heat source for the Wapsalit geothermal system.