Characteristic of geothermal fluid at East Manggarai, Flores, East Nusa Tenggara

Abstract

The research area is located in East Manggarai and its surrounding area, Flores. In the study area there are two geothermal systems, i.e. Mapos geothermal system which is associated with Anak Ranakah volcano and Rana Masak geothermal systems which is associated with Watuweri volcano. The difference within these systems is shown by the relative content of conservative elements of Cl, Li and B. Geothermal surface manifestations in Mapos include 4 hot springs having temperatures of 34,3-51,4°C and bicarbonate and sulphate-bicarbonate waters; the discharge area in Rana Masak consist of 3 hot springs with temperatures of 38-46,6°C and chloride and chloride-bicarbonate water. Stable isotopes δ18O and δD analyses showed that the geothermal fluid derived from meteoric water. The Mapos geothermal system is a high temperature system having reservoir temperature of 250-270°C with natural heat loss of 230 kW. The Rana Masak geothermal system is a low temperature system having reservoir temperature of 120-140°C with natural heat loss of 120 kW.