272-8 Mechanisms of Vein Formation in Serpentinized Peridotite - Insights from Hydro-chemo-mechanically Coupled Modeling

Session: Faults, Fractures, and Geomechanics for the Energy Transition (Posters)

Presenting Author:

Authors:

Abstract:

Hierarchical fracture systems filled with carbonate veins are ubiquitous in serpentinized peridotite outcrops. They often appear in orthogonal sets, forming grid-like cross fracture patterns on the surface. Many fundamental questions on the mechanisms of vein formation are yet to be fully explored. For example, was the fracture network a pre-existing one or developed as a result of carbonate precipitation? If the fracture network was pre-existing, did it form due to a mechanical origin because of in situ earth stress or a hydro-chemo-mechanically coupled action because of the volume increase hydration or serpentinization reactions? In this work, the serpentinization process, modeled using the Mg-end member reaction of forsterite hydration serving as a proxy, is examined numerically through hydro-chemo-mechanically coupled finite element modeling (FEM). We assume diffusion to be the dominant fluid transport mechanism and employ an eigen strain within the framework of elasticity to account for volume expansion due to the geochemical reaction. Specifically, we analyze how tensile stress could be induced due to serpentinization and whether the tensile stress will be sufficient to cause tensile failure, potentially creating orthogonal sets of fractures resembling the so-called “kernel model” proposed in O’Hanley (1992). Better understandings of these questions could not only shed light on the natural geological processes during crustal deformation of the earth but also provide insights into engineering processes such as potential geological hydrogen production in peridotite rocks as well as carbon mineralization, where mafic and ultramafic rock mass may be engineered to serve as reservoirs for capturing and permanently storing anthropogenic CO₂ in form of carbonate minerals.

Reference

O’Hanley, D. S. (1992). Solution to the volume problem in serpentinization. Geology, 20(8), 705-708.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9055

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