Rheology of Mantle Minerals In Subducted Slabs: Limits on Deep Seismicity

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

Weidner 9909266 The deep focus earthquake process remains poorly understood. The strength of the material of the subducting slab may limit the distribution and size of these events. Furthermore, plastic instabilities remain as a possible cause of these events. The data obtained in this study will define the limitations imposed by the rheology of the faulting material on these events. The PI and colleagues will investigate the rheological properties of the olivine, wadsleyite, and ringwoodite phases in the pressure and temperature domain of a subducting slab. A synchrotron x-radiation source coupled with a multi-anvil high-pressure system will be used to conduct an experimental study of these materials in the pressure range up to 20 GPa and temperatures from room temperature to 1200C. The approach is to characterize the rheology and underlying processes that govern flow in the appropriate pressure and temperature conditions of a subducting slab. The investigators will determine the temperature dependence of the strength of the materials and the stress - strain rate relation at these conditions. This information will yield estimates of activation energies for the flow process. With transmission electron microscopy, they will characterize the dislocation density and structure of the material corresponding to different regimes of the deformation. Taken together, these data will be useful to extrapolate to possible conditions that exist in the subducting slab and will be useful for constraining the earthquake process as well as delineating