Hydrothermal Alteration and the Evolution of the Lahendong Geothermal System, North Sulawesi, Indonesia

Abstract

The Lahendong geothermal system (North Sulawesi) is the first geothermal system in eastern Indonesia developed for electricity generation. It is a liquid-dominated system located in steep terrain with thermal manifestation at about 750 m asl. To date the system is penetrated by 27 wells to measured depths ranging from 1500 to 2500 m. The reservoir rocks are andesite and rhyolite ranging from to 2.2 to 0.5 Ma. The typical temperature inside the thermally active area is 250 oC at about 1000 m bsl. Lahendong is also the first geothermal system developed in an arc – arc collision setting. A purpose of this study is to describe the hydrothermal alteration and evolution of a system in such setting ...