192 Twenty-Seven Years of Advances in Understanding Salt-Sediment Interaction: A Legacy of Katherine A. Giles (Posters)

This session seeks contributions that highlight the interconnections between coevolving salt bodies and depositional systems in continental, shallow marine and deep marine settings. Field, geobiological, geophysical, and geochemical, as well as theoretical, physical and numerical modeling studies are encouraged.

Tuesday, 21 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Simmered, Pickled, and Squeezed – Survival in the Salty Deep Biosphere

Paper number: 192-4
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

From a geomicrobiology perspective, the fact that salt tectonic processes can bring deeply buried strata into near-surface environments opens the intriguing question of whether microbes thriving in evaporite basins can first be incorporated within layered evaporite deposits (‘salt’) and later be exhumed during salt diapirism. Is burial in a layered evaporite sequence a one-way ticket to certain death, or an opportunity for evolution to optimize resilience to burial and exhumation in salt bodies?  We explore how the burial of evaporitic rocks, which results in an increase in temperature and pressure, impacts the viability of an ensemble of evaporite and non-evaporite rocks that are encased in halite to function as a microbial “lifeboat” on salt’s journey from evaporite basin to salt diapir. We found that a combination of gypsum, organic-rich dolostone, and shale, as well as iron-rich sandstones – lithologies that are frequently found in the cap of salt walls from the Paradox Basin – offers microbes ample metabolic opportunities, such as the reduction of sulfate and ferric iron, and the buffering of environmental pH by the presence of dolostone. Moreover, the combination of sulfate and ferric iron reduction produces sulfide and ferrous iron, which combine to form sulfide minerals, removing metabolic waste products that could become a challenge for the microbes' survival.   However, as temperature and pressure increase with burial, the situation becomes more nuanced. Early diagenesis and initial hydrocarbon generation profoundly impact dissolution, cementation, porosity, and permeability, as well as the availability of water, metabolizable constituents, and nutrients. Diverse lithologies found in the cap of salt diapirs provide a unique window into the intricate interplay between microbes and the physical processes that impact non-evaporite rocks entrained in salt diapirism. For instance, the finding of over-compacted sandstones in the cap of Paradox Basin salt walls is in stark contrast to the carbonate intra-salt stringer hydrocarbon play in Oman. Their inventory of authigenic minerals and fabrics is a so far untapped archive to learn more about deep biosphere processes.  

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412016

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