ANALYSIS OF TECTONIC ACTIVITY DURING THE LATE ARCHEAN IN THE ENGLISH RIVER SUBPROVINCE, ONTARIO CANADA

Earth is the only planet in our solar system with evidence of active plate tectonics, but we know little about why. Understanding when plate tectonics began is important for understanding other Earth processes, and tectonics of other planets in the solar system. The accretion of the first true continents during the Archean make plate tectonics seem plausible. However, the lack of subduction related metamorphic rocks makes this hypothesis ambiguous. To determine if plate tectonics was active in the Archean eon, we conducted fieldwork in the English River Subprovince (ERSP)­—a 1000 km linear metasedimentary belt within the Superior Province of Ontario, Canada—and collected samples of garnet-biotite-cordierite gneiss and associated igneous rocks for detailed petrology and geochronology. We will use these data to determine the timing and patterns of metamorphism, magmatism, and deformation across the ERSP and test proposed plate- and non-plate-tectonic hypotheses for the formation of the Superior Province.