Geophysical constraints on granite related non-volcanic geothermal systems in West Kalimantan, Indonesia

Salsabila Siregar; Berwyn Dzaky Radhitya

doi:10.58524/jograv.v1i1.105

Authors

Salsabila Siregar Department of Physics, Institut Teknologi Sumatera Author
Berwyn Dzaky Radhitya Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba Author

DOI:

https://doi.org/10.58524/jograv.v1i1.105

Keywords:

Non-volcanic geothermal system, Subsurface structure, Lithological control, Granite intrusion, West Kalimantan

Abstract

Geothermal resources are typically concentrated in active volcanic provinces; however, significant geothermal potential also occurs in non-volcanic environments, commonly referred to as non-volcanic geothermal systems. In Indonesia, such systems have been documented in the Riau Archipelago, Bangka Island, Belitung Island, and Kalimantan. This study investigates the subsurface structural and lithological controls of three non-volcanic geothermal prospects in West Kalimantan Province, namely Sape, Sibetuk, and Nanga Dua. Granitic rocks are interpreted as a potential heat source governing reservoir development, although groundwater heating may also be influenced by pressure gradients within sedimentary basins. To constrain the controlling rock units and subsurface geometry, gravity observations were processed and integrated into two-dimensional (2D) and three-dimensional (3D) forward modeling. The results reveal distinct dominant lithologies at each prospect. The Sape geothermal prospect is primarily associated with slate units with an estimated density of 2.6 g/cm³. The Sibetuk prospect is characterized by granitic formations with a comparable density of 2.6 g/cm³, whereas the Nanga Dua prospect is mainly developed within sandstone formations with a density of 2.31 g/cm³. The 2D–3D models consistently indicate that granitic bodies beneath the Melawi–Ketungau Basin represent the most plausible geothermal heat source in the study area. This work provides one of the first integrated gravity-based structural interpretations for non-volcanic geothermal prospects in West Kalimantan. The findings offer a geophysical framework for ranking exploration targets and reducing uncertainty in geothermal resource assessment within sedimentary basin settings.

References

1. Hosono, T., Hartmann, J., Louvat, P., Amann, T., Washington, K. E., West, A. J., Okamura, K., Böttcher, M. E., & Gaillardet, J. (2018). Earthquake-induced structural deformations enhance long-term solute fluxes from active volcanic systems. Scientific Reports, 8(1), 1–12. https://doi.org/10.1038/s41598-018-32735-1

2. Zhang, Z., Yao, H., Wang, W., & Liu, C. (2021). 3-D crustal azimuthal anisotropy reveals multi-stage deformation processes of the Sichuan Basin and its adjacent regions. Journal of Geophysical Research: Solid Earth, 127, e2021JB023289, 1–17. https://doi.org/10.1029/2021JB023289

3. Liu, S., Suardi, I., Xu, X., Yang, S., & Tong, P. (2021). The geometry of the subducted slab beneath Sumatra revealed by regional and teleseismic traveltime tomography. Journal of Geophysical Research: Solid Earth, 126(1), 1–29. https://doi.org/10.1029/2020JB020169

4. Dewi, K. C. S., Siregar, R. N., Ningati, T. I., Pulungan, Z. N., Indriyawati, A., & Takahashi, H. (2025). Analysis of subsurface faults using 3D gravity method based on satellite image data: Insights into Indo-Australian and Eurasian plate subduction in the formation of an accretionary prism. International Journal of Hydrological and Environmental for Sustainability, 4(3), 135–148.

5. Hariyono, E., & S, L. (2018). The characteristics of volcanic eruption in Indonesia. In Volcanoes – Geological and Geophysical Setting, Theoretical Aspects and Numerical Modeling, Applications to Industry and Their Impact on Human Health. https://doi.org/10.5772/intechopen.71449

6. McCaffrey, R. (2009). The tectonic framework of the Sumatran subduction zone. Annual Review of Earth and Planetary Sciences, 37, 345–366. https://doi.org/10.1146/annurev.earth.031208.100212

7. Hristov, V., Stoyanov, N., Valtchev, S., Kolev, S., & Benderev, A. (2019). Utilization of low enthalpy geothermal energy in Bulgaria. IOP Conference Series: Earth and Environmental Science, 249(1). https://doi.org/10.1088/1755-1315/249/1/012035

8. Taruna, R. M., & Banyunegoro, V. H. (2018). Earthquake relocation using double difference method for 2D modelling of subducting slab and back arc thrust in West Nusa Tenggara. Jurnal Penelitian Fisika dan Aplikasinya (JPFA), 8(2), 132–143. https://doi.org/10.26740/jpfa.v8n2.p132-143

9. Collings, R., Lange, D., Rietbrock, A., Tilmann, F., Natawidjaja, D., Suwargadi, B., Miller, M., & Saul, J. (2012). Structure and seismogenic properties of the Mentawai segment of the Sumatra subduction zone revealed by local earthquake traveltime tomography. Journal of Geophysical Research, 117, 1–23. https://doi.org/10.1029/2011JB008469

10. Jihad, A., Muksin, U., Syamsidik, & Ramli, M. (2021). Earthquake relocation to understand the megathrust segments along the Sumatran subduction zone. IOP Conference Series: Earth and Environmental Science, 630, 012002. https://doi.org/10.1088/1755-1315/630/1/012002

11. Xu, J., & Kono, Y. (2002). Geometry of slab, intraslab stress field and its tectonic implication in the Nankai Trough, Japan. Earth, Planets and Space, 54(7), 733–742. https://doi.org/10.1186/BF03351726

12. Kusuhara, F., Kazahaya, K., Morikawa, N., Yasuhara, M., Tanaka, H., Takahashi, M., & Tosaki, Y. (2020). Original composition and formation process of slab-derived deep brine from Kashio Mineral Spring in central Japan. Earth, Planets and Space, 72(1). https://doi.org/10.1186/s40623-020-01225-y

13. Malod, J. A., Karta, K., Beslier, M. O., & Zen, M. T. (1995). From normal to oblique subduction: Tectonic relationships between Java and Sumatra. Journal of Southeast Asian Earth Sciences, 12(1–2), 85–93. https://doi.org/10.1016/0743-9547(95)00023-2

14. Li, C. F. (2011). An integrated geodynamic model of the Nankai subduction zone and neighboring regions from geophysical inversion and modeling. Journal of Geodynamics, 51(1), 64–80. https://doi.org/10.1016/j.jog.2010.08.003

15. Stern, R. J. (2002). Subduction zones. Reviews of Geophysics, 40(4), 3-1–3-38. https://doi.org/10.1029/2001RG000108

16. Utama, H. W., Mulyasari, R., & Said, Y. M. (2021). Geothermal potential on Sumatra Fault System for sustainable geotourism in West Sumatra. JGE (Jurnal Geofisika Eksplorasi), 7(2), 126–137. https://doi.org/10.23960/jge.v7i2.128

17. Tabei, T., Hashimoto, M., Miyazaki, S., Hirahara, K., Kimata, F., Matsushima, T., Tanaka, T., Eguchi, Y., Takaya, T., Hoso, Y., Ohya, F., & Kato, T. (2002). Subsurface structure and faulting of the Median Tectonic Line, southwest Japan inferred from GPS velocity field. Earth, Planets and Space, 54(11), 1065–1070. https://doi.org/10.1186/BF03353303

18. Tongkul, F. (2017). Active tectonics in Sabah – seismicity and active faults. Bulletin of the Geological Society of Malaysia, 64, 27–36. https://doi.org/10.7186/bgsm64201703

19. Maryanto, S. (2017). Geo techno park potential at Arjuno–Welirang volcano hosted geothermal area, East Java, Indonesia (multi geophysical approach). AIP Conference Proceedings, 1908. https://doi.org/10.1063/1.5012712

20. Sujitapan, C., Kendall, J. M., Chambers, J. E., & Yordkayhun, S. (2024). Landslide assessment through integrated geoelectrical and seismic methods: A case study in Thungsong site, southern Thailand. Heliyon, 10(2), e24660. https://doi.org/10.1016/j.heliyon.2024.e24660

21. Chambers, J., Holmes, J., Whiteley, J., Boyd, J., Meldrum, P., Wilkinson, P., Kuras, O., Swift, R., Harrison, H., Glendinning, S., Stirling, R., Huntley, D., Slater, N., & Donohue, S. (2022). Long-term geoelectrical monitoring of landslides in natural and engineered slopes. The Leading Edge, 41(11), 768–776. https://doi.org/10.1190/tle41110768.1

22. Whiteley, J. S., Watlet, A., Uhlemann, S., Wilkinson, P., Boyd, J. P., Jordan, C., Kendall, J. M., & Chambers, J. E. (2021). Rapid characterisation of landslide heterogeneity using unsupervised classification of electrical resistivity and seismic refraction surveys. Engineering Geology, 290, 106189. https://doi.org/10.1016/j.enggeo.2021.106189

23. Martinho, E. (2023). Electrical resistivity and induced polarization methods for environmental investigations: An overview. Water, Air, & Soil Pollution, 234. https://doi.org/10.1007/s11270-023-06214-x

24. Kusumayudha, S. B., Lestari, P., & Paripurno, E. T. (2018). Eruption characteristic of the sleeping volcano Sinabung, North Sumatera, Indonesia, and SMS gateway for disaster early warning system. Indonesian Journal of Geography, 50(1), 70–77. https://doi.org/10.22146/ijg.17574

25. Meju, M. A., & Le, L. (2002). Geoelectromagnetic exploration for natural resources: Models, case studies and challenges. Surveys in Geophysics, 23, 133–205.

26. Lange, D., Tilmann, F., Henstock, T., Rietbrock, A., Natawidjaja, D., & Kopp, H. (2018). Structure of the central Sumatran subduction zone revealed by local earthquake travel-time tomography using an amphibious network. Solid Earth, 9(4), 1035–1049. https://doi.org/10.5194/se-9-1035-2018

27. Lin, J. Y., Sibuet, J. C., Hsu, S. K., & Wu, W. N. (2014). Could a Sumatra-like megathrust earthquake occur in the South Ryukyu subduction zone? Earth, Planets and Space, 66(1), 1–8. https://doi.org/10.1186/1880-5981-66-49

28. Siringoringo, L. P., Sapiie, B., Rudyawan, A., & Sucipta, I. G. B. E. (2024). Origin of high heat flow in the back-arc basins of Sumatra: An opportunity for geothermal energy development. Energy Geoscience, 5(3), 100289. https://doi.org/10.1016/j.engeos.2024.100289

29. Hochstein, M. P., & Sudarman, S. (1993). Geothermal resources of Sumatra. Geothermics, 22(3), 181–200. https://doi.org/10.1016/0375-6505(93)90042-L