CAREER: Using Upper Mantle Circulation Models to Evaluate the Role of the Asthenosphere: Tectosphere Contrast and Subduction Dynamics for Global Plate Tectonics

University Of Southern California, Los Angeles CA

Investigators

Abstract

Using upper mantle circulation models to evaluate the role of the asthenosphere:tectosphere contrast and subduction dynamics for global plate tectonics Research focuses on global, numerical convection models with realistic plate boundaries, rheological and thermo-chemical contrasts, and improved constraints from seismology. The force partitioning in the mantle affects intraplate and plate boundary seismo-tectonics, and studying the mantle system by mechanical modeling holds the key to understanding plate motions and geologically recorded tectonic events. Efforts are divided into two research projects which are interrelated and have strong educational components. Project one uses circulation computations for an inversion of seismology data to evaluate the range of viscosity variations that are required by observables and laboratory results on the creep behavior of rocks (viscous tomography). Project two incorporates faulted margins into a global model (slabs, keels, and plates). Slabs drive and control the speed of the plates, and a more realistic inclusion of plate boundaries into global models is needed. It is evaluated to what degree slabs and trench motions vs. the tectosphere: asthenosphere contrast control global dynamics such as geopotential fields and seismic coupling. The unifying theme of research and educational efforts is the use of global flow models and structure derived from seismology and mineral physics. The goal is to arrive at a new kind of mantle circulation model that elucidates the roles of the asthenosphere in shaping plate tectonics and organizing deep Earth structure. The educational efforts in this project focus on course material for a new numerical methods class and two solid earth software modules for exploring mantle flow and tomography, both openly developed and freely shared. The goal is to allow learning through experimentation with modified research tools. Those tools are customizable so that they are useful for both general undergrad and graduate classes. Efforts strengthen the quantitative skills of students needed to tackle interconnected problems; useful for grad students to solve outstanding questions in mantle dynamics, and for non-specialists who need to make informed choices during planetary environmental challenges. Work contributes to a more transparent representation of disciplinary research results where traditional means of scientific communication are becoming unduly limiting. By providing both fundamental training in quantitative analysis and examples for novel seismological and geodynamical model sharing, the robustness of extra-disciplinary constraints are easier to evaluate. This is crucial if we are to accelerate progress on complex problems in plate tectonics and earth science in general.