GEOPHYSICAL AND GEOLOGICAL MODELLING BASED ON THE GRAVITY DATA OF TALU-TOMBANG’S FIELD, WEST PASAMAN REGENCY, WEST SUMATERA PROVINCE

• Main Author: Silitonga, Antonius
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/84419
• Institution: Institut Teknologi Bandung

Indonesia has geothermal potential of 28.617 MW due to tectonic and volcanic activity. One of the geothermal areas in Indonesia is the Talu-Tombang Geothermal Field, Lebak Regency, Banten. The purpose of this study is to make subsurface geophysics and geology model of Pamancalan Geothermal Field. In this study, the data used are Complete Bouguer Anomaly (CBA) data and elevation data obtained from the PSDMBP research result in the Talu-Tombang Geothermal Field in 2012. Value of complete Bouguer anomaly ranges from -40 to 20 mGal. The separation of complete Bouguer anomaly to regional and residual anomaly was done with two different methods, the butterworth method and the moving average method. The results of the anomaly of both methods are compared and the one that was most optimal were chosen for further data processing. The residual anomaly of the butterworth method and moving average method shows anomaly results with a range of values of -14 to 18 mGal and -20 to 26 mGal, respectively. The butterworth method residual anomaly map was chosen for further data processing because it better shows the geological conditions based on the geology map of the TaluTombang Geothermal Field than the moving average method residual anomaly map. Based on the modelling results, there is low anomaly respond which is interpreted as Cubadak 2 pyroclastic (?? = -0.28 gr/cc) and high anomaly respond which is interpreted as intrusion (?? = +0.47 gr/cc). The bedrock of this area is interpreted as phyllite (?? = +0.12 gr/cc) which is pretertiary in age. Modelling results also show two faults which are interpreted as hot spring controlling faults, namely Tombang Fault which is interpreted as the fault that is controlling Tombang 2 Hot Spring and Talu Fault which is interpreted as the fault that is controlling Talu Hot Spring.