Fluid flow in the subsurface: Geochemical, sedimentological and microbial interactions

Flow systems in the Earth's subsurface represent dynamic interfaces where geological, chemical, and biological processes converge. Driven by pressure gradients, thermal regimes, and tectonic activity, these systems play a crucial role in redistributing elements, forming mineral deposits, and hosting unique microbial ecosystems. Despite their significance, the intricate interactions governing fluid migration, geochemical transformations, and biological adaptations remain incompletely understood. Findings from recent studies in modern microbialites provide valuable insights into the evolution of fluid flow in subsurface environments and its surface expressions.

Investigations along the modern Dead Sea shores have highlighted the critical role of tectonic discontinuities and pre-existing geological structures in controlling vertical fluid migration pathways. These findings emphasize how fault zones can act as conduits or barriers to fluid movement, influencing mineral precipitation, hydrothermal vent activity, and subsurface microbial habitats. The combination of geochemical tracers and detailed sedimentological analyses reveal the temporal and spatial dynamics of fluid-sediment interactions as well as the role of microbial communities. Similarly, studies in recent lacustrine environments in Patagonia, where ongoing microbialite formation occurs, have demonstrated the influence of diverse groundwater sources on the development of carbonate buildups. These findings underscore the role of fluid chemistry and hydrodynamics in shaping microbial communities, and the resulting microbialite structures and carbonate precipitation processes.

These studies highlight the importance of interdisciplinary approaches in deciphering fluid flow dynamics. By integrating geochemistry, sedimentology, and microbiology, we can better interpret modern and ancient fluid-driven systems. Bridging observations from active fluid flow systems with paleo-records enhances our understanding of the long-term implications of fluid flow on Earth's carbon cycle, climate regulation, and biosphere evolution. They further provide potential analogs for extraterrestrial habitable environments.