Deciphering the State of the Lower Crust and Upper Mantle With Multi-Physics Inversion

Abstract

The composition of the lower crust is a key factor in understanding tectonic activity and deformation within the Earth. In particular, the presence or absence of melt or fluids has strong control on tectonic evolution. Multi-physics inversion results from the western United States indicate that tectonic inheritance plays a much stronger role in determining the location of melt in the lower crust than previously thought. Even in a currently active area such as the Yellowstone Hotspot, the results suggest that fluid dominated structures and fluid free regions are located directly next to each other. This is incompatible with the commonly used model of recent tectonic activity as a main controlling factor for the presence of fluids or melt. These results have global implications for how geophysical models are interpreted and how they can be related to geodynamic simulations.