Petrogenetic investigation of Neoarchean anorthosite-greenstone associations in the Superior Province, Canada

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The geological models proposed to explain the origin of Archean anorthosite-greenstone associations in the Superior Province of Canada require re-evaluation within the context of new high-precision geochemical data. Over the next five years I plan to study the field, microscopic and geochemical characteristics of Archean anorthosite-greenstone associations in the Superior Province, to constrain their petrogenesis and geodynamic setting. The anorthosite-greenstone associations to be studied include the Neoarchean Bad Vermilion Lake (Ontario) and Doré Lake (Quebec) complexes. I will systematically sample each lithological unit in these associations and analyze them for major and trace elements and isotopes (Nd, Pb, O), to improve our understanding the petrogenetic origin of these rocks. The geochemical characteristics of each rock type in the anorthosite complexes and spatially associated volcanic rocks are expected to reflect petrological processes responsible for the compositional and isotopic variations in these rocks and their sources. Trace elements and Nd, Pb and O isotopes are sensitive to petrogenetic processes and can be used to distinguish between different petrogenetic processes. These petrological processes can then be linked to the regional scale Neoarchean geodynamic processes in the Superior Province. Two hypotheses will be tested: (1) anorthosite-greenstone associations are genetically related and represent relict Archean oceanic crust; and (2) they are petrogenetically unrelated and do not represent Archean oceanic crust. The results of this project will have the following significance: (1) enhance our knowledge on the petrogenetic origin of Archean layered anorthosites and associated mafic to ultramafic intrusive rocks; and (2) the Canadian resource industry will benefit from this research program given that anorthosites and associated ultramafic rocks have high potential for chromite, vanadium, copper, nickel, and PGE (Platinum Group Elements) mineral deposits.