Characteristics of Mountain Arjuno-Welirang Geothermal Jawa Timur Province, Indonesia

Abstract

The analysis of the Arjuno-Welirang geothermal field Jawa timur Province, Indonesia. The field situated at longitute beetwen 112o29’12’’and 112o37’29’’ and at latitute beetwen -7o37’36’’ and -7o49’51’’. The surface manifestation consist of hot spring, fumarol and alteration rocks. The hot spring discharge expose at elevation 1350 m asl, 1600 m asl, fumarol and solfatara spreadout within the summit of Mt. Arjuno and Mt. Welirang, at elevation about 3100 m asl. The alteration rocks spreadout in the two location such as at surounding Plupuh Crater and at a lower part of the Mt. Pundak. Geology Analysis, such as surface manifestation and geology structure analysis and geochemical analysisi conducted due to chracterises the reservoir condition of the Mt. Arjuno-Welirang geothermal system. Tentaive result of the research show that the Arjuno-Welirang geothermal system is chlorite water, althoght the result of reservoir analyss indicated the bicarbonat water (HCO3). Its caused by interction between reservoir water with meteoric water and water level, closed to the surface. The reservoir temperature up to 175°C. The reservoir rocks of the system is andesitic basaltic rocks. The hydrothermaly system should be product of water interaction with vulkano-magmatik. The hot water before reach the surface predicted has interacted with sediment rocks. The other hand, that the manifestation is product the lateral flow or out flow.