Palash Kumawat

Serpentinization, redox conditions, and metabolic energy production within
shallow subduction zones: windows to carbon cycling and chemosynthetic life driven by modern and ancient serpentinite mud volcanism

Geofuel emissions, including molecular hydrogen (H₂) and methane (CH₄), released during serpentinization, play a crucial role in supporting chemosynthetic life. While extensive research has been conducted exploring the hydrothermal vents; our understanding of low-temperature serpentine-hosted fluid seepage sites, particularly those in the forearcs of the subduction systems, remains limited. Serpentine Mud Volcanoes (SMVs) are among the most prominent fluid and sediment expulsion features associated with the Mariana subduction system. These SMVs expulse highly variable slab-derived fluids (high pH of up to 12.5, high CO₃^2-, H₂, CH₄, acetate, and formate) and serpentine mud; mixed with clasts of various natures.

The foundation of these life-harboring landscapes is the deeply rooted serpentinization reaction that provides sufficient geofuels to host a chemosynthetic ecosystem in the vast desolated deep sea. Serpentinization is hypothesized to be a vital reaction involved in the earliest biochemical systems. The serpentinizing environment, along with essential precursor biomolecules must have served as a prebiotic soup for life to emerge from!

The Mariana SMVs are the only known active mud volcanoes of this kind. But did serpentine mud volcanisms exist in the geologic past? The Coast Ranges of California and Oregon preserve sedimentary serpentinite units which are suspected to be fossil mud volcanoes, which existed during the Jurassic-Cretaceous age. 

This Ph.D. project aims to examine both modern Mariana SMVs in the Pacific and the fossil analogs of SMVs in the Coast Ranges of California and Oregon. The research involves a comprehensive investigation utilizing petrological and geochemical analyses to elucidate the conditions required for the production of H₂ and CH₄ in contemporary and ancient forearc systems. Additionally, the study incorporates extensive biomarker analyses to explore the chemosynthetic extremophilic microbial communities, in an attempt to evaluate the conditions that facilitated the emergence and evolution of life on early Earth.