The comprehensive results of geological, geophysical and geochemical surveys for geothermal resources in the Gou area, Flores Island, Indonesia

摘要

The aim of this paper is to identify and describe the possibilities of the utilization of geothermal energy in the Gou area, Flores Island, Indonesia. The general view of the comprehensive results of integrated geoscientific surveys in the Gou area is as follows. Stratigraphy consists of Quaternary volcanic and sedimentary rocks underlain by Tertiary basement rocks. Thermal features on the surface occur along a NE-SW trending fault, namely the Mengeruda fault. These features include hot springs, fumaroles and altered rocks. The temperatures of hot springs at Managara, Watuh Wuti and Tukapela reach 47.5 deg C while their flow rates are 5 - 7 l/min. All hot springs are characterized by high concentration of acid sulphate water discharges at the surface. Also, surface argillic alteration occurs in the vicinity of hot springs along the Mengeruda fault. The high contour values of soil gas mercury are concentrated around the Managara and Watuh Wuti hot springs, where the maximum concentration of Hg reaches 564 ppb. The lateral distribution of the low resistivity zone (less than 10 ohm-m) at AB/2=1000 m is also concentrated around these hot springs, and the contour is open to the northeast direction. This prospective area covers a minimum of about 2 km~2. The vertical distribution of the low resistivity zone is between 350 - 700 m below the surface.