Structural Control on the Thermal Manifestations in South Sulawesi, Indonesia
Mochamad NUKMAN, Ade ANGGRAINI, Pamungkas YULIANTORO
[Geophysics Study Program, Gadjah Mada University, Indonesia]
Field campaign for updating thermal manifestations information and their structural pattern at South Sulawesi shows that all (three sites) of geothermal prospects indicate that the discharging hot springs are associated with the faults that bounded the thermal system. The discharging thermal springs have temperatures range of 38-72 deg.C, mostly neutral pH, and a combined ~8 l/s of fluid discharge. The springs are located at the wrench fault system, i.e. NNE-SSW left lateral of East and West Walanae Faults, which are those in parallel relationship forming a depression zone. The field findings (fractures pattern, veins & fault breccia) show that fracture striking NNE-SSW is mostly occurring at the vicinity of discharging springs. With referring to E-S regional compression, the attitude of measured joint at three locations (Lejja, Sulili and Massepe), i.e. NNE-SSW and N-S, are likely a dextral or antithetic component of major sinistral fault of Walanae Fault system. The earthquake swarms are occurring in the western part of the interaction fault zone, where the hottest springs (i.e. Sulili complex) are discharging. The cluster of deep earthquakes (EQ) at northern part of West Walanae Fault is indicating the possible location of a deep heat source associated with faults acting as conduits transferring heat to shallower levels. Among other thing, our findings show that not all geothermal fields in Indonesia are hosted in volcanic setting, but also controlled by crustal heat systems.
|        Topic: Geology||Paper Number: 12011|