Geodynamics Relationship of Sabak Back Arc Volcanic and Geragai Geothermal Features, Tanjabtim, Jambi, Indonesia

Abstract

Jambi Sub-basin is a sedimentary back-arc basin in Sumatra with the numerous geodynamic processes of the extensional basin. It is a prospect and producer of hydrocarbon Sumatra, Indonesia, and it's part of the South Sumatra Basin. The presence of trachy basaltic lava on the Sabak (Jambi Sub-basin), Tanjabtim, guides back-arc volcanism. Geragai geothermal features are the Northwestern part of Sabak back-arc volcanic as a hint of the connection between both of them. The geological investigation of geodynamics is essential for understanding the possibility between Sabak Back Arc Volcanic and Geragai Geothermal Features. Geological methods research consists of geological outcrop data such as lithology characteristics, the structural geology element, the physical part of geothermal manifestation, and mineral composition analyzed. Geological evidence of the Sabak Back Arc Volcanic compile of trachy basaltic lava is scoria, vesicular, amygdaloidal, and rophy structure. These are perpendicular that magma eruption, which extrusive processes. A geological survey to show Geragai geothermal features is composed of hot springs with temperatures about 50ºC -55ºC, pH 6.2 -6.8, the appearance of Claystone Kasai Formation, and swamp sediment. Bicarbonate fluid indicates a strong influence of meteoric water and mixing processes of the interaction fluid geothermal with wall rock and thickness of water table. The existence of dextral fault with Northwestern -Southeastern orientation of Sabak Back Arc Volcanic the continued to Geragai geothermal hot spring manifestation, were buried under Alluvium. The dextral mark directly continues to appearance geothermal features manifestation. It assures there is a facility of the pathway the geothermal features on the surface manifestation. The geothermal system on Geragai has a spatial connection to back-arc volcanism on Sabak. The convinced heat transfer dormant volcanic of Sabak Back Arc Volcanic to Geragai geothermal features passes through dextral fault system.