The Geology and Geothermal System of the Dieng Geothermal Field, Central Java, Indonesia

Abstract

The Dieng Geothermal Field is currently the only geothermal system in Central Java that has been producing electricity. Previous studies suggest that the field consists of three prospect areas, namely Sileri, Sikidang, and Pakuwaja. Re-interpretation of volcanostratigraphy through DEMNAS and field checking has been done in our study. In general, volcanism in Dieng field, based on previous researches and our ground check - started since the volcanic activity of Mt. Prau in the eastern margin as the oldest phase of volcanism. A younger and smaller eruption centers then emerged in the SW part from NW to SE are, Pagerkandang, Pangonan-Merdada, and Pakuwaja. These NW-SE trending younger volcanic centers are spatially associated with the distribution of thermal manifestations which are dominated by solfataric and steam heated fluid discharges. The volcanism and the types and distribution of thermal manifestations may give hints of different geothermal systems within the area. When combined with the results of subsurface geologic data and supporting information from previous studies, it will be an important knowledge to better understand of the geology and geothermal system of the field.