Integrated 2D–3D gravity modeling reveals structural controls of a granite-hosted non-volcanic geothermal system in West Kalimantan, Indonesia

Succi Angling Situmorang; Ahmad Said

doi:10.58524/jograv.v1i1.107

Authors

Succi Angling Situmorang Department of Physics, Institut Teknologi Sumatera Author
Ahmad Said Friedrich-Schiller-University Jena, Friedrich-Schellingstr Author

DOI:

https://doi.org/10.58524/jograv.v1i1.107

Keywords:

Non-volcanic geothermal exploration, Gravity inversion, Crustal heat production, Granite intrusion, Granite-hosted

Abstract

West Kalimantan, Indonesia, forms part of a granitic province associated with the Southeast Asian tin belt, characterized by felsic intrusions enriched in heat-producing elements such as uranium (U), thorium (Th), and potassium (K). The radiogenic decay of these elements may contribute to localized crustal heat accumulation, suggesting potential for non-volcanic geothermal systems. The Meromoh geothermal area is one such manifestation suspected to be structurally controlled by underlying granitic bodies. However, the subsurface architecture and the geometry of potential heat sources remain poorly constrained. This study aims to characterize the subsurface structure of the Meromoh geothermal system using satellite-derived gravity data integrated with two-dimensional (2D) forward modeling and three-dimensional (3D) inversion. Secondary datasets including longitude, latitude, elevation, and Free-Air Anomaly (FAA) were obtained from the TOPEX global gravity database and processed to generate a Complete Bouguer Anomaly (CBA) map. The CBA values range from 15.8 to 61.7 mGal, indicating significant subsurface density contrasts across the study area. The integrated modeling results reveal a crustal structure composed of the Kayan Sandstone Formation, Pendawan Formation, Dasit and Bawang units, and the Pueh Granite Formation. The Pueh Granite is interpreted as a deep-seated intrusive body extending from near-surface levels to a depth of approximately 11.6 km. Structural discontinuities and density contrasts suggest that the granite intrusion plays a key role in controlling geothermal manifestations. These findings provide new geophysical constraints on granite-hosted geothermal systems in West Kalimantan and highlight the importance of gravity-based structural modeling for evaluating non-volcanic geothermal potential in radiogenic provinces.

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