[SCG56-P01] Numerical prediction of effect of olivine content for proceeding of serpentinization
Keywords:Serpentinization, Discrete Element Method, Oceanic lithosphere
The numerical simulation based on two-dimensional distinct element method (DEM) combining fluid advection and reaction (Shimizu and Okamoto., 2016) was conducted to examine the effect of amount of olivine grains to unreacted matrix. We consider a simple volume increasing hydration reaction (150% volume increase), and the rock model consist of reactive part (olivine) and unreactive part (plagioclase and pyroxene). We conducted five conditions varying distance between each olivine grains. As the result, the olivine grains made connected fracture network, which increase in permeability and reaction progress. However, when too low olivine content, it could not make enough fracture for reaction proceeding. In the other hands, when too much olivine amount condition, the permeability and bulk reaction progress become less because volume expansion caused fracture clogging which inhibited further fluid infiltration to fresh olivine grains.
These results suggest that (1) an increase of olivine amount results in development of fracture network to percolate fluids, but (2) too much olivine amounts prevent the fluid flow as volume-expansion close the fractures which obstruct fluid penetration. The discrepancy between natural observation and numerical modeling for dunite suggest the importance of other fluid pathways such as nano-scale pores in serpentine for complete serpentinization.
Shimizu, H., Okamoto, A., 2016. The roles of fluid transport and surface reaction in reaction-induced fracturing, with implications for the development of mesh textures in serpentinites. Contributions to Mineralogy and Petrology, 171, 73.