Global paleogeography and geodynamics of the Proterozoic to Paleozoic transition

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Supercontinent breakup, dispersal and assembly is a fundamental feature of global geodynamics, both as a tracer of long-term global cycles and as a possible driver of core, mantle and crustal secular evolution. The most recent billion years of Earth evolution has seen a succession of supercontinents, from Rodinia to Gondwana and Pangea to Eurasia, involving the relative motions of plates, mediated via evolving plate boundaries. The evolution of global paleogeography provides an important context for understanding fundamental secular changes in the Earth, including past paleoclimate extremes (such as global glaciation), seawater geochemistry and the Neoproterozoic Paleozoic diversification of life. During this time the Earth appears to have also undergone large geodynamic changes including possible major true polar wander events, reorganization of global mantle convection, and changes in the geometry and strength of the geodynamo. These questions are all best addressed within a global plate tectonic framework which requires primary paleomagnetic-based data. Paleomagnetism is a key quantitative geophysical tool for defining the past motions of continents and terranes. Paleomagnetism, in conjunction with geochronology, is ideally suited to deduce the orientation and timing relationships between terranes and continents, as representatives of the ancient plates and their motions. My proposed paleomagnetic and tectonic research program investigates the interaction of the paleocontinent Laurentia (North America + Greenland and Northern Ireland, Scotland) with West Gondwana and Gondwana-related terranes from the Late Neoproterozoic breakup of Rodinia through the mid Paleozoic assembly of Pangea. Early Paleozoic paleogeography of signature events such as the Great Ordovician Biodiversification Event (GOBE) and changes in paleoclimate will be developed via new work in Laurentia and South China. Fieldwork is anticipated to take place on a project-by-project basis in Atlantic Canada/Ontario, Anti-Atlas of Morocco and South China. Paleomagnetic laboratory work will be done at the Western Paleomagnetic and Petrophysical Laboratory (WPPL) to obtain primary results. This paleomagnetic research, along with associated geochronology and other supporting research, will be done as an integral part of several student theses and via collaborations. The overall goal of this proposed research program is to solve key questions concerning plate tectonic relations between isolated paleocontinents, terranes and elements of Gondwana in the as-yet poorly understood global paleogeography from Ediacaran though Silurian time, to provide a crucial context for major events in the biosphere and paleoclimate. The proposed research program will place my students and their work at the heart of current debates about the significant events and processes which drastically changed Earth during the transition from the Neoproterozoic world of Rodinia to the Late Paleozoic world of Pangea.