Shijie Zhong, Professor, Department of Physics, University of Colorado, Boulder
Abstract. Arguably two most important observations about the Earth's dynamics are the present-day degree-2 mantle structure (i.e., two major seismically slow anomalies under Africa and central Pacific that are separated by circum-Pacific seismically fast anomalies) and supercontinent Pangea's assembly and breakup in the last 500 Ma. These observations raise some important questions. What are the mechanisms that control Pangea's assembly and breakup and are responsible for formation of long-wavelength mantle structure? Do we expect degree-2 mantle structure during Pangea time? In this presentation, I will discuss 1) how mantle dynamic processes may generate very long-wavelength mantle convection and structure, 2) how such processes may be responsible for Pangea formation and breakup, and the present-day degree-2 mantle structure, and 3) how we may build a general framework to understand the Earth's dynamic evolution for the last 500 Ma including large-scale volcanism, continental vertical motions, and magnetic polarity reversals.