| Abstract |
Success of modular power plant development and economic considerations revived interest in the Dauin Geothermal Prospect. This prompted a recent geophysical reinvestigation of the area using magnetotellurics (MT). The MT survey delineated two regions of shallow occurring high-resistivity (>50. 100 º┘-m) overlain by a zone of low resistivity (í┬ 10 º┘-m), one of which centers beneath Lagunao Dome, and another beneath Mt. Talines and Cuernos de Negros. The former, a larger anomaly, is related to the Palinpinon geothermal system at the Southern Negros Geothermal Production Field (SNGPF), while the latter, a smaller anomaly, is thought to define a separate geothermal system, referred to as the Dauin prospect. The high-resistivity anomalies are associated with high temperature but low conductivity mineral alteration products (illite, epidote, chlorite, etc.) that dominate most geothermal systems. The low-resistivity (í┬10 º┘-m) layer is associated with clay hydrothermal alterations (smectite and illite-smectite) that normally occur at regimes of intermediate temperatures (~70¿¼C). The resistivity model supports the idea of two geothermal systems separated by a zone of high-sulfidation. This high-sulfidation zone coincides with the region of intermediate resistivity likely defined by the Malingin Fault, which also separates the two high-resistivity anomalies. A single heat source possibly fuelling the two systems at deeper levels, however, is not discounted. |