Geothermal Geology of the Mataloko Area, Central Flores, Nusa Tenggara, Timur, Indonesia

Abstract

The Mataloko area, the survey area of this study is located in the central part of Flores, where many alteration zones are found including Nage and Mengeruda, centering around the Mataloko geothermal area. With regard to the generation process of the Mataloko alteration area, it is considered that a low temperature acidic hydrothermal water (about 100Åé) has contributed to its generation along with the influence of an alteration cap rock developed deep under the ground. According to this study the following geothermal model is suggested. Geothermal steam and H2S gas were selectively separated from the hydrothermal water being affected by the cap rock under the ground. This rose toward the surface and flowed into the underground water to generate the acidic hydrothermal water. Consequently it is expected that a predominant geothermal reservoir should exist deep under the Mataloko area. On the other hand, pyrophylite was detected in the central part of geothermal activities of the Nage alteration zone, where many hot springs exist. Pyrophylite is a hydrothermal alteration mineral, which indicates the involvement of a high temperature acidic hydrothermal water (about 200-300Åé) in its generation process. Judging from this model, it is considered that the survey area around Mataloko has optimal conditions for geothermal power generation.