Constraining the interplay of geodynamics with the biosphere and atmosphere across the Archean-Proterozoic boundary

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This study aims to track changes in global geodynamics across the Archean-Proterozoic boundary to characterize the potential link between tectonics and the evolution of the biosphere and atmosphere. Earth's present-day surface environments are the product of 4.5 billion years of change that reflects global-scale geologic, atmospheric, and biologic processes. This secular evolution is punctuated with a handful of hallmark events that permanently and irreversibly altered chemical and biological systems worldwide. In particular, the transition from the Archean to Proterozoic Eons (2.5 billion years ago) is considered by many to have been the most significant period of time in Earth history. The geologic changes at this time carry implications for significant shifts in geodynamics which in turn may have influenced biologic evolution and atmospheric oxygenation. Numerous recent studies have demonstrated significant shifts in the geologic record from ~2.5 to ~2.1 billion years ago, including changes in the composition of igneous and sedimentary rocks, zircon, and atmosphere. The Archean-Proterozoic transition is also characterized by a lull in the preserved geologic record, rapid rise of continental crust above sea level, and the earliest episode of low-latitude glaciation. The short-term goals of this proposal are (1) to provide high resolution temporal constraints on shifts of oxygen and sulfur isotopic signatures in sedimentary and igneous rocks associated with Archean-Proterozoic transition and (2) to evaluate the geodynamics of discrete geologic regions during the geologic lull of 2.5-2.1 billion years ago, and the relationship between mountain building, rise of continents above sea-level, and the transfer of sedimentary material into the deep Earth. The isotopic research of this project will use cutting-edge micro-analytical techniques at leading geochemical facilities in Canada including the large-geometry ion probe facility at the University of Alberta as well as the analytical facilities at Queen's University. The current research program will support the research of eight HQPs (2 PhD, 2 MSc, 4 BSc). Students will receive an education in field geology, laboratory and analytical methods, and the process of interpreting and communicating scientific data to the scientific community and general public. The long-term goal of this research program is to provide a link between secular changes in the mantle that profoundly influenced the evolution of the biosphere and atmosphere that led to changes in the composition of sediment and the igneous rocks derived from deep in Earth's crust. The importance of this research program is a demonstration of the intertwined processes of the deep Earth with the biosphere and atmosphere. The new testable framework resulting from this research will provide avenues of continued science inquiry for many years to come.