Rinjani and Propok Volcanics as a Heat Sources of Geothermal Prospects from Eastern Lombok, Indonesia

Abstract

The eruptive history of Sembalun–Propok-Rinjani volcanic complexes during the young Quaternary age had been studied. Those young volcanic complexes are as a good geothermal heat source of the Eastern Lombok prospects. The ages of Sembalun volcanic rock complex were formed during the last of 0.45 Ma. The pyroclastics of youngest Rinjani volcanic products was formed during a stratocone building stage between 0.012-0.006 M.a. The volcanic activity migrated more 5 km eastward for a low activity stage, erupting Propok pumice and Lembar dacitic lava flows. The Propok, Lembar and Rinjani volcanics seems to be as an up flow zone and good heat sources for a geothermal prospect of eastern Lombok Island. These areas are recognized by 10 Ohm-m resistivity zones of low frequency MT data and CSMT profiles. Out flow of neutral warm springs (25-38oC) discharge at the eastward and northeast, approximately 2 km of the Propok craters. Therefore, these information may give an early assessment of Lombok geothermal prospects.