Mafic magmatism in layered intrusions through time and space

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Terrestrial planetary crusts are dominated by rocks crystallized from basaltic magma. These magmas form by partial melting of the mantle and they erupt at the Earth's surface where they produce spectacular volcanic features, including the mountainous mid-ocean ridges, linear chains of hotspot volcanoes, and vast outpourings of flood basalts that may be triggers for catastrophic biosphere collapse. Most basaltic magmas do not erupt and instead they stall and crystallize in shallow to deep crustal reservoirs such as layered intrusions that preserve stunning rock records of the processes by which magma evolves. The overall goal of my proposed research program is to evaluate the timescales and processes by which basaltic magmas form planetary crusts. This will be accomplished through investigation of the geochronology and geochemistry of select layered intrusions. The research will take advantage of analytical developments, especially trace element and isotopic micro-analysis, and utilize state-of-the-art instrumentation at the Pacific Centre for Isotopic and Geochemical Research.******Key to understanding the relationships between layered intrusions and crustal evolution is (1) the duration and rate at which magmas accumulate in the crust, (2) the thermal history of individual intrusions, and (3) the composition of the mantle source, all of which remain poorly constrained for layered intrusions. I will develop integrated time-temperature-composition frameworks for individual intrusions that will serve as benchmarks for comparison across the geological record. I will study a range of ancient (Archean) to young (Cenozoic) intrusions, including those where the basic principles of crystallization in magma chambers have been established (Skaergaard, Stillwater) and Canadian intrusions that provide opportunities to test current and emerging paradigms on the physical state of magma reservoirs (Fox River, Polaris). I will also investigate the use of non-traditional stable isotopes as a new geochemical tool for tracking mineral-controlled processes in layered intrusions that will yield novel insights into their crystallization conditions and sequences.******Layered intrusions contain world-class deposits of chromium, platinum group elements, and vanadium, metals that are vital to society in general. The results of this research will have direct implications for the origin of magmatic ore deposits in intrusions in Canada and elsewhere in the world. The ultimate goal of this work is to provide new scientific constraints on the timescales and pathways of magmatic processes and cooling that produce the striking rocks present in layered intrusions. The results will be used to challenge basic concepts of magma evolution and development of the Earth's crust through time and space.