Speaker: Thorsten Becker
In this overview presentation, geared toward a specialist mantle geodynamics and structural seismology audience, I discuss some of the ongoing research that USC Geodynamics has been involved in (http://geodynamics.usc.edu/~becker/projects.html), focusing on open questions pertaining to oceanic plate systems. Using global plate motions, past and present, we can construct time-integrated models of mantle structure, predict the locations of subducted slabs and advected plume conduits. Those synthetic models can be compared with what is observed in seismic tomography, yielding constraints on radial and vertical mass transport. At the surface, seafloor age distributions are expected to change over time, allowing an analysis of the change of heat transport over the last 120 Ma and studying variations in spreading rate. For more recent times, geodynamic analysis can explore structure and dynamics in more detail, and I provide a brief overview of how seismic anisotropy can be used to benchmark geodynamic reference models, and perhaps explore second order features such as volatile variations underneath the Pacific plate. A key parameter constrained by anisotropy are net rotations of the lithosphere, and I show results from modeling as to the excitation mechanisms of net rotations, as well as a global study on their role in affecting seismicity within subducted slabs.