Characteristic and Mixing Mechanisms of Thermal Fluid at the Tampomas Volcano, West Java, Using Hydrogeochemistry, Stable Isotope and 222Rn Analyses

Abstract

The Tampomas Volcano is a Quaternary volcano located on Java Island and controlled by a west-northwest-east-southeast (WNW-ESE) regional fault trend. This regional structure acts as conduits for the hydrothermal fluids to ascend from a deeper system toward the surface and, in the end, mix with groundwater. In this research, water geochemistry, gas chemistry and isotopes 2 H, 18 O and 13 C were used to explore the subsurface fluid characteristics and mixing mechanisms of the hydrothermal fluids with groundwater. In addition to those geochemical methods, soil-gas and dissolved 222 Rn observations were performed to understand the geological control of fluid chemistry. Based on the analytical results, the hydrothermal system of Tampomas is only developed at the northeastern flank of the volcano, which is mainly controlled by NE-SW structures as deep fluid conduits, while the Cimalaka Caldera Rim around Sekarwangi act as the boundary flow of the system. This system is also categorized as an "intermediate temperature system" wherein fluid is derived from the interaction between the volcanic host-rock at 170 ± 10 • C mixed with trace organic gas input from sedimentary formation; afterwards, the fluid flows laterally and is diluted with groundwater near the surface. Soil-gas and dissolved 222 Rn confirm that these permeable zones are effective conduits for the ascending thermal fluids. It is found that NE faults carry higher trace elements from the deeper system, while the circular feature of the Caldera Rim acts as the boundary of the hydrothermal system.

Radon Activity Concentrations in Natural Hot Spring Water: Dose Assessment and Health Perspective

“…This paper is the first report on 222 Rn measurements in tourism natural hot spring water in Indonesia. Previous studies related to radon measurements in Indonesia included measurements of air at dwellings [12][13][14][15], 222 Rn in water samples [15], 222 Rn in geothermal and geosciences [16]…”

Hydrogeochemical Characteristics and Conceptual Model of the Geothermal Waters in the Xianshuihe Fault Zone, Southwestern China

“…Geothermal resources have become a popular clean energy source due to its clean and renewable affinities [1]. Geothermal springs, as an important constituent of geothermal resources, have become a hot research topic so far [2][3][4][5][6].…”

Natural Sources of Ionization and Their Impact on Atmospheric Electricity

“…to the thinner atmosphere and thus higher GCR-related ionization rate; Rn-222 emission (spots in regions of enhanced volcanic and geological activity) (Iskandar et al, 2018). The overall spatial variability of the fair-weather vertical current is within a factor of two roughly between 1.5 and 3 pA/m 2 .…”

“…Our results imply that during a quiet period (Scenario 1; see Figure 5a), the atmospheric current density is affected by several competing processes of roughly equal importance: the geomagnetic shielding of GCR (visible as the latitudinal gradient); orography (enhanced spots on the Antarctic Plateau and Himalaya) due to the thinner atmosphere and thus higher GCR‐related ionization rate; Rn‐222 emission (spots in regions of enhanced volcanic and geological activity) (Iskandar et al, 2018). The overall spatial variability of the fair‐weather vertical current is within a factor of two roughly between 1.5 and 3 pA/m 2 .…”