A melt inclusion study of the Sudbury Igneous Complex (Ontario, Canada) : evidence for two-liquid immiscibility and constraints on trace element distribution

Abstract

The Sudbury Igneous Complex (SIC), Ontario, Canada, is the product of a massive bolide impact and has been studied extensively due to its rich endowment of magmatic sulfide (Ni-Cu-platinum-group element) ore deposits. In this study, apatite-hosted melt inclusions from the Main Mass and quartz diorite offset dikes are analyzed for trace and major element compositions. The results of apatite-hosted melt inclusion major and trace element chemistry show two contrasting Si- and Fe-rich coevally (co-entrapped) melt inclusions are present in the SIC Main Mass and offset dikes. The apatite-hosted melt inclusions from the mineralized Whistle offset dike are enriched in Ni by up to 4 orders of magnitude compared to those melt inclusions trapped in the units stratigraphically higher in the SIC. This study provides the first in-situ determination of actual ore metal concentrations from early trapped melt of the SIC and trace element partitioning behavior between immiscible liquids in nature.