The three-dimensional thermo-mechanical signature of ridge subduction and slab window migration

Abstract

We present a series of three-dimensional numerical models investigating possible thermal and mechanical effects of ridge subduction and slab window migration. Ridge subduction is a fundamental process of plate tectonics, and the geologic manifestations in the overriding lithosphere have been investigated in many convergent margin settings. Many of the geologic effects of slab window migration (e.g., anomalous high- T metamorphism in the forearc, non-arc-like magmatism in the volcanic arc) are explained primarily by the introduction of a region of hot, upwelling asthenospheric mantle in the subduction zone environment. Using end-member boundary conditions and idealized geometries, our models address the thermal and corresponding mechanical manifestations of slab window migration, and our results provide a general agreement with observations from interpreted regions of slab window migration. Our models show that protracted heating in the forearc region should result in protracted high-temperature metamorphism, associated rheologic weakening and strain partitioning and changes in the topographic uplift pattern in regions affected by slab window migration. Although these models are idealized, they do provide valuable insight into the geodynamics of slab window environments and provide a valuable starting point for further exploration.