| Abstract |
Integrated Geophysical Studies of Palu-Koro Depression Zone, Indonesia: Implications for Geothermal Resources in Bora Central Sulawesi ¹Alanda IDRAL, ²Wiwi R. MANSOER ¹Geotamindo, ²Centre for Geological Resources - Indonesian Geological Agency idral_idral@yahoo.com Keywords: Bora, depression, fault, Palu-Koro, gravity, geomagnetic, magnetotelluric, ABSTRACT Palu-Koro depression zone, here in referred to as the study area, called as Bora geothermal field, such as numbers of geothermal field in Sulawesi, is a non volcanic hosted geothermal area, lies aproximately 30 km to the south of Palu, the Capital City of Central Sulawesi province and belongs to Sigi-Biromaru Regency. The study area is characterized by geothermal surface manifestations which consists of hot waters (T. 90,1 °C), hot ground (T.100,6 °C), and altered rocks. The area is overlain by Quaternary sediment, Tertiary plutonic intrusive rocks and Pre-Tertiary Metamorphics. The terrain is characterized by extensive faulting forming numerous almost N-S ridges and fault scarps. The objective of the Geophysical methods (gravity, geomagnetic and magnetotelluric) were carried out to delineate the heat source, the possible boundary of the geothermal reservoir, deep structures that control flow of geothermal fluid and evaluate the geothermal resource potential of the area. The integrated geophysical studies in the area indicate that Bora geothermal system lies in the floor of Palu-Koro depression zone which is considered associated to the tectonic activities (Palu-Koro fault) that is trending nearly N- S. These activities also caused the geothermal manifestation in the area come out to the surface. The heat source is considered to be associated with young plutonic rocks as the result of the tectonic activities. |