Chemical heterogeneities in the early Earth and planetary analogues: their formation, preservation and destruction

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A fundamental question in Earth and planetary sciences is how the planets formed and how they evolved through time. Geochemical and numerical models, as well as planetary analogs suggest that Earth accreted from complex processed materials and then evolved rapidly after its formation. Early events such as core segregation, mantle differentiation and crust formation seem to have occurred shortly after the Earth's accretion. Furthermore, the composition of the Earth's mantle was modified by the continued accretion of materials during the final stages of formation. In the past few years, the development of short-lived isotopic chronometers has allowed chronological studies of the events that followed shortly the Earth's accretion. Mixing through mantle convection and crustal recycling associated with plate tectonics has attenuated the magnitude of primordial mantle heterogeneities. However, recent documentation of early-formed isotope variations in Archean rocks requires the persistence of primordial chemical reservoirs for > 1 billion years. Over the next five years my research program will focus on three key problems involving Earth and planetary sciences:1) What are the nature and timing of the major events affecting the chemical composition of the early Earth's mantle?2) How long did early-formed chemical heterogeneities survive in the convective mantle, and what was the style of convection of the early Earth?3) Is the early evolution of the Earth comparable to other planetary analogues like the asteroid Vesta?This research program is strongly focused on the development, improvement and acquisition of data from extinct and long-lived radioactive isotope systematics, as well as obtaining siderophile element abundances for different planetary materials. These geochemical tools are ideal to constrain core and mantle early evolution, and investigate the timing and chemical consequences of late accretionary additions. The findings of this project will help to improve models of the internal dynamics of the Earth during its early stages of development, and provide geological knowledge about the oldest terrains in northern Canada. This research program is designed to involve several undergraduate and four graduate students who will acquire a unique set of skills that are relevant to both academia and industry.