Effects of serpentinization and deserpentinization on rock elastic properties in subduction zones

Serpentinization and deserpentinization are critical metamorphic reactions in subduction zones and have gained substantial attention in recent years. These metamorphic reactions significantly alter mineral assemblages and microstructures in subduction zones, thereby affecting their elastic properties and geodynamic behaviors. This paper comprehensively reviews and further investigates the potential effects of serpentinization and deserpentinization on elastic properties, which include: (1) the elastic properties of serpentine single crystals are briefly reviewed, (2) the effects of serpentinization and deserpentinization on isotropic elastic properties are compiled, and (3) the microstructural evolution of rocks during these metamorphisms are summarized and their effects on elastic properties are calculated and analyzed. It is found that serpentinization reduces the isotropic elastic moduli and seismic wave velocities while augmenting Poisson's ratio, whereas deserpentinization induces contrary changes in these elastic properties. Elastic anisotropies, significantly influenced by rock microstructure, exhibit greater complexity than isotropic ones; and the overall elastic anisotropies increase with serpentinization while decreasing with deserpentinization. The effects of metamorphism on elastic properties in specific directions largely depend on the microstructural evolution. Furthermore, both serpentinization and deserpentinization of peridotites may contribute to trench-parallel seismic anisotropy observed in the forearc mantle. Understanding the effects of these metamorphisms on elastic properties will play an important role in the determination of the geodynamics, tectonic evolution, and seismology in subduction zones.