Thermal History of Mataloko Area, Flores Island, Indonesia

Abstract

Mataloko and nearby Nage geothermal areas are studied by X-ray diffraction, chemical analyses and thermoluminescence (TL) dating. Acidic white colored alteration halos are developed in both areas and thermal manifestations are predominant. Altered minerals found in these areas are quartz, cristobalite, tridymite, sericite, kaolinite, montmorillonite, alunite, sulfur and glass. Reacting fluid temperature is higher in Nage than Mataloko. Chemically, many silicified zones in both areas have high silica contents. Ages of volcanic and altered rocks were determined by TL method. Age range of 9 volcanic rocks is 31.5ka to 160ka. Stratigraphical correlation has not yet been done but all ages are young enough for geothermal development. Alteration ages also indicate the same range from 36.8ka to 183ka for 6 samples. It is also a good range for reserving heat beneath the area. However, age of alteration has a problem about chemical leaching of U, Th and K.