Geothermal Fluids Beneath Songa – Wayaua Area, Bacan Island, North Maluku Province - Indonesia

Abstract

The Songa - Wayua geothermal area is located in the middle of Bacan Island, North Maluku Province. Indication of geothermal potential in the area is characterized by surface thermal features, such as hot springs, fumaroles, mud pools, hot grounds, steaming grounds, silica sinter and altered rock. The surface features are Pelepele Besar/ utara, Pelepele Kecil/ selatan, Babale Langsa/ Lansa, Pado pado/ Tawa and Wayaua. Their temperatures vary between 45.1 - 101.60 C, and they have a normal pH of hot water acids, of about 6,54 - 6,99. The geothermal manifestations here are covered by volcanic and metamorphic rocks, which are associated with the N 330º E lineament of recent volcanics.
All hot waters represent a high concentration of chloride. Two samples derived from immature waters, while three others are in partial equilibrium. The geothermometer calculation for the thermal reservoir beneath the area varies between 221 and 254 C. The relation between hydrogen and oxygen isotopic ratios of thermal spring waters in Songa-Wayaua shows enriched 18O content, it lies reality distance from the MWL (meteoric water line). This means all hot spring waters are presumably derived from a reservoir beneath the geothermal manifestations.