"CSEDI: From fine to global scales: Integrated studies of the structure, dynamics, and mineral physics of the lower mantle"

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The solid earth, the earth excluding the oceans and atmosphere, is a giant heat engine responsible for not only continental drift and plate tectonics, but also geological hazards (especially those from giant earthquakes) and for the formation of mineral and hydrocarbon resources. The purpose of this research is to better understand how this heat engine works by focusing on the earth's lower mantle. The lower mantle is the largest region of the planet by volume and the heat sources and physical processes there play a critical role in determining how the heat engine works. In this project, we will take a cooperative approach in which we will understand the basic material properties of earth materials under extreme pressures and temperatures; incorporate those experimental results into three-dimensional simulations of the earth's interior; and then test the predictions of both approaches with detailed studies of seismic waves passing through the earth's deep interior. We believe that there are three areas in which our work will have broad impact. First, our specialized work on the lower mantle is of broad interest to the scientific community because it improves our understanding of how the earth works as an interconnected, dynamic system. Second, we will partially support and mentor three Caltech graduate students in the Seismology Lab. and thereby contribute to the training of the next generation of scientists in the U.S. Third, our multidisciplinary approach will allow our students to become leaders in the internationally competitive field of global geophysics. Seismologists have revealed that the mantle side of the core mantle boundary (D") is extraordinarily complex with a myriad of fine structure (e.g. ~10 km to a few 100 km's). Thermal and chemical heterogeneity, solid-solid phase transitions, and melting within the lower mantle are probably all required in order to explain observed structure and suggest that the lower boundary of the mantle is as complex as the continental crust. Understanding the origin of the fine scale structure of the lower mantle, in general, and D", in particular, is key toward understanding how the solid Earth works as a globally interconnected system. In order to better understand this region from the different means available, this work will involve collaboration between a seismologist, a geodynamist, and an experimental mineral physicist.