June Cho

MSc student
University of British Columbia

Mafic layered intrusions (MLI) are excellent natural laboratories for observing and understanding fundamental petrologic processes, such as magmatic differentiation and fractional crystallization. The ~56 Ma Skaergaard intrusion of Eastern Greenland is an ideal setting in which to consider these concepts since it formed by slow-cooling of a magma in a closed system. Despite extensive literature on the intrusion, research into some isotopic systematics is minimal. My MSc project, supervised by Drs. James Scoates and Dominique Weis, aims to establish the variability in lead isotopic compositions of plagioclase from the Skaergaard intrusion by laser ablation ICP-MS. The trace element and Pb isotope systematics will be used to constrain the parent magma and mantle source compositions.

I first became interested in layered intrusions through my NSERC undergraduate student research award (USRA) project with PCIGR. I identified and characterized symplectites (reactive microstructures that develop during the last stages of crystallization) in the Kiglapait layered intrusion of Labrador, Canada. The study of the textural and compositional record of symplectites provides insight on the chemical evolution of the interstitial liquid.

This summer project really opened my eyes to the applications of geochemistry and petrology to magmatic systems. It also led to my MSc project – the opportunity to study one of the most influential layered intrusions in the world!