Karst cave system formation driven by coupled deep-seated processes: modelling and case studies

The upper crust evolves through tightly coupled thermal, fluid-flow, mechanical, and geochemical processes, often termed thermo-hydro-mechano-chemical (THMC) interactions. These processes involve multiple nonlinear feedbacks operating across wide spatial and temporal scales, making their interpretation challenging. The integrated outcome of these hidden processes is often recorded in water-rock interactions and alteration patterns, providing valuable clues. In particular, morphologies of hypogene karst and cave systems formed by deep-seated ascending fluids are of great importance. This type of karst is distinct from the shallower, commonly more evident epigenic karst formed by surface infiltration of CO₂-rich meteoric water. Despite being often less visible, it is globally extensive and in many regions dominant, producing voluminous and structurally complex cave systems. As such, hypogene karst offers a unique natural laboratory for investigating coupled upper-crustal dynamics [1–2].

Here, we consolidate field observations of different components into a THMC conceptual scenario for hypogene cave system formation, which is explored using numerical and theoretical modelling. The results reproduce and help clarify hypogene cave morphologies that have been difficult to explain. Several global case studies demonstrate systematic relationships between cave development and structural-tectonic context, supporting the proposed scenario. This work improves understanding of obscured coupled subsurface processes, with relevance to geothermal systems, critical-mineral exploration, and geohazard assessment.

References

[1] Klimchouk, A., in Hypogene karst regions and caves of the world, 1–39, Springer (2017).

[2] Roded, R. et al., Commun. Earth Environ. 4, 465 (2023).