Characteristic of Geothermal System at Semurup Manifestation, Kerinci: Geological and Geochemistry Investigation-Based

Semurup Village on Kerinci Regency, Jambi is indicated potential for geothermal resources; it is proved by the presence of hot springs (Gao Luluk, Gao Dili, and Gao Mudik), non-active geyser, and silica sinter deposit. This research aimed to investigate reservoir characteristics which the approach was to interpret the Semurup hot spring fluid type and reservoir temperature based on elements fluid contained. This research was carried by the analysis of B, Al, Ca, Mg, Na, K, Li, F, Cl, SO4, HCO 3 contained of hot spring for reservoir characterization conducted by Cl-SO4-HCO3, B-Li-Cl, and Na-K-Mg ternary diagram and conductive silica geothermometer for reservoir temperature estimation. Semurup hot spring was classified by volcano-tectonic geothermal system, because it was associated with Quartenary Lumut Volcano and Sumatran Fault Zone. Unit stratigraphy was composed by Eosene pyroclastic rocks of Bandan Formation (kaoliniteclay minerals, calcite, feldspar) and Undifferentiated Volcanic Rock Formation (silica minerals, chlorite, and calcite). Geological setting was possibly vary of hot springs (chloride -bicarbonate) and deposits (silica -bicarbonate). There were three types of geothermal manifestation, which were neutral hot spring, geyser, and silica sinter. The result showed that GaoLuluk fluid was dominated by Cl at 53.06% while that of GaoMudik was high in bicarbonate at 72.81%. Silica conductive geotermometers gave equilibirum reservoar temperatures ranging from 166°C -241°C. Based on the geological and geochemical investigation, the reservoir fluid of Semurup manifestation had occured dilution with calcite-contains on groundwater and the reservoir temperature was classified as moderate -high, which was high potential for geothermal energy resource.