CAREER: Microphysical evolution of highly sheared polymineralic rocks

Washington University, Saint Louis MO

Investigators

Abstract

The theory of plate tectonics is the basis for most Earth science, providing context for interpreting such diverse phenomena as earthquakes and volcanoes, mountain building, and global climate. In spite of its broad scientific and societal importance, there are still fundamental unanswered questions about the underlying physical mechanisms of plate tectonics. The basic differences between the manifestation of tectonics on Earth and other terrestrial bodies are a major outstanding question in geophysics and planetary science. This research applies novel experimental approaches to study how rocks deform at the pressures and temperatures of planetary interiors to help understand the origins of plate tectonics on Earth. To fulfill these research objectives, large strain torsional deformation experiments will be conducted on rocks of crustal and mantle composition. These experiments will be performed in the PI's newly built Large Volume Torsion apparatus (LVT), which has been optimized for experimental investigations at pressures of up to 6 GPa and temperatures of up to 1300 C. The focus of these investigations will be on the microphysical interaction between various mineral phases, in polymineralic rocks. The goal is to better understand how large shear strains modify the rheological properties of realistic rocks, and identify the conditions where these data deviate from experiments conducted to small strains on monomineralic material. Microstructural data will be incorporated into numerical models to simulate how variations in rheology influence the dynamical evolution of tectonic plates. This project also includes an integrated plan for teaching and research in rock mechanics at the undergraduate level. Few undergraduate curricula incorporate rock mechanics, and more exposure is needed to broaden research capabilities in this critical area. The PI will be developing a research-grade bench-top rock deformation apparatus that will be incorporated into the curricula of several undergraduate colleges with strong programs in Earth Science. Through curriculum and infrastructure development, this effort seeks to expand the number of undergraduate students who consider further research in experimental rock deformation.