Title: Impact of reaction-induced fracture on fluid flow and hydration in the lithosphere
Abstract: Hydration of the lithosphere occurs within the oceanic plate at mid-ocean ridges and subduction zone outer rise faults, and within the mantle wedge corner in subduction zones. However, the extent of hydration is limited by the local permeability of the lithosphere. Experimental observations indicate that the permeability of hydrating rock is dynamic due to the solid volume increase associated with many hydration reactions that can both clog fluid pathways and fracture the surrounding rock. The latter process, called reaction-induced fracture, accelerates hydration by creating new fluid pathways and increasing the reactive surface area, and may be critical for extensive hydration of the lithosphere. We use hydraulic-chemical-mechanical numerical models to investigate reaction-induced fracture as a function of several parameters, including the tectonic stress state and rheological contrast between anhydrous and hydrated rock, that may be relevant to hydration near plate boundaries. The results have implications for fluid migration and the spatial extent of hydration along the subduction interface, within the mantle wedge corner, and along faults within the oceanic lithosphere. We compare the results to geophysical and geologic observations of hydration at plate boundaries, and propose that reaction-induced fracture may help explain the contrasting degrees of hydration observed in the mantle wedge corner of subduction zones.
Biography: Jeremiah McElwee is a PhD student working in Dr. Ikuko Wada’s lab at the University of Minnesota, Twin Cities. He completed his BSc at the University of California, San Diego, and expects to complete his PhD at the University of Minnesota in 2026. His current research focuses on discrete element modeling to investigate feedbacks between (de)volatilization reactions and mechanical deformation. In addition to fluid-rock interaction, he is also interested in large-scale subduction zone dynamics, especially in the forearc.
To join virtually: Zoom
Contact: mcelw020@umn.edu
Recording: Zoom Recording (will be available within a week after the seminar)