3/18AM (Special session) Development of materials and resource circulation research by new researchers

[2K0201-05-03] Exploring Hidden Geothermal System through an Integration of Soil Gas Data at the Mt. Endut Field, Indonesia

○Mochamad Iqbal^{1[Doctoral course],2}, Taiki Kubo¹, Koki Kashiwaya¹, Katsuaki Koike¹ (1. Kyoto University, 2. Institut Teknologi Sumatera)

Chairperson: Akihisa Kizaki (Akita University)

Keywords:hidden geothermal system, CO2 flux, carbon-13 isotope, radon-222, data integration

This research investigates the potential of hidden geothermal systems (HGS) for sustainable energy, with a focus on the Mount Endut region in Banten, West Java Island, Indonesia. Despite the absence of surface geothermal manifestations, Mt. Endut is regarded to house two geothermal systems: the medium-temperature Cikawah geothermal system and the elusive Endut HGS. This study employs an integrated approach involving CO₂ flux measurements, carbon-13 (δ¹³C-CO₂) isotopic analysis, and radon (²²²Rn) emissions profiling to uncover these concealed geothermal resources. CO₂ flux was measured at 234 sites using the accumulation chamber method, revealing a range from 0.15 to 7.42 g m^-2 day^-1 with the average of 1.63 g m^-2 day^-1. The δ¹³C-CO₂ composition varied significantly, suggesting a primary biogenic origin with signs of a biogenic-hydrothermal mix. These findings contribute to identifying anomalies indicative of HGS in the Mt. Endut field. Estimations of the geological structure and potential geothermal resource are further deepened by the radon measurements at 68 locations, ranging from 797 to 24,133 Bq/m³ with the average of 7749 Bq/m³. Consequently, the areas with the lower CO₂ flux and the specific patterns of δ¹³C-CO₂ and radon emission can be judged to be highly possible as the Endut HGS.