- 1Faculty of Physics, University of Warsaw, Warsaw, Poland (piotr.szymczak@fuw.edu.pl)
- 2Department of Earth & Environmental Sciences, University of Minnesota, Minneapolis, MN, USA (roi.roded@mail.huji.ac.il)
- 3Institute of Earth Sciences, The Hebrew University, Jerusalem, Israel (einatah@mail.huji.ac.il)
- 4Institute of Earth Sciences, The Hebrew University, Jerusalem, Israel (amos.frumkin@mail.huji.ac.il)
- 5Department of Earth and Planetary Sciences, The Weizmann Institute of Science, Rehovot, Israel (nurit.weber@mail.huji.ac.il)
- 6Institute of Earth Sciences, The Hebrew University, Jerusalem, Israel (boaz.lazar@mail.huji.ac.il)
Extensive karstification and speleogenesis in carbonates can be induced by the rise of hydrothermal fluids. However, the contribution of different geochemical and hydrogeological mechanisms to this process remains unclear, and a variety of reactivity sources, as well as hydrogeological mechanisms, were suggested. These include renewed reactivity by mixing of different solutions or condensation corrosion above the groundwater table [1-4]. However, the role of cooling and retrograde solubility of carbonates as a major hypogene speleogenesis mechanism was often considered negligible (e.g., [1] & [2]) or attributed to the development of diffuse karst [3]. Here, using mathematical modeling, we study speleogenesis induced by upwelling thermal flow, enriched by deep CO2 fluxes, that upon cooling leads to large retrograde solubility and extensive dissolution. The conceptual model we suggest, consistent with our case study of hypogene caves [5], considers upwelling of focused channelized thermal flow through faults. Upon approaching an impermeable caprock this flow is diverted sideways and flows radially along permeable bedding planes and fractures in limestone strata (inception horizons). Radially dispersed hot flow then cools rapidly via heat transfer to the surrounding rock, leading to focused dissolution and, over time-scales of 10 000 - 100 000 yrs, to speleogenesis near the inlet. Because the caves are isolated and breakthrough to the surface is not achieved during speleogenesis, the overall permeability and fluid flux do not appreciably change, so that dissolution remains localized, forming a cave. The model also predicts that maximal fluid cooling and dissolution are attained slightly downstream from the inlet, for which corresponding field observations are presented. These findings show that geothermal heat loss by upwelling of thermal fluids, in conjunction with deep CO2 fluxes, may shape and extensively karstify carbonate aquifers in the upper crust, with the formation of sizable speleological structures [6].
[1] Palmer, A.N., Geol. Soc. Am. Bull., 103(1), 1-21, 1991
[2] Klimchouk, A.B., In: White, W.B., Culver, D.C. (Eds.), 2nd ed. Academic Press, New York, 748–765, 2012
[3] Andre, B.J. and Rajaram, H., Water Resour. Res., 41, W01015, 2005
[4] Dreybrodt, W., Gabrovsek, F., Romanov, D., Processes of Speleogenesis: A Modeling Approach, ZRC Publishing, 2005
[5] Frumkin, A. et al., Geol. Soc. Am. Bull., 129(11-12), 1636-1659, 2017
[6] Roded, R., Aharonov, E., Frumkin, A., Weber, N., Lazar, B., and Szymczak, P. , Commun. Earth Environ., 4, 465, 2023
How to cite: Szymczak, P., Roded, R., Aharonov, E., Frumkin, A., Weber, N., and Lazar, B.: Upwelling geothermal flow and retrograde solubility lead to hypogene speleogenesis in carbonate aquifers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17039, https://doi.org/10.5194/egusphere-egu25-17039, 2025.
