U-Pb Geochronology of Felsic Plutons in Neoarchean Sturgeon Lake Greenstone Belt, Ontario, Canada

Abstract

The emplacement of granitoid plutons in Archean granite-greenstone belt terranes can provide a more complete magmatic and deformational history than the volcanic and sedimentary rocks. Granitoid plutons in greenstone belts record tectonic processes and crust-mantle interactions from the earliest formed basement assemblages, to synvolcanic and syndeformation, to post-tectonic events. Previous mapping in the Sturgeon Lake greenstone belt constrained spatial relationships between plutonic rock and supracrustal assemblages but lack definitive timing of plutonic emplacement. This study represents ongoing research that characterizes the plutonic suites in the Sturgeon Lake greenstone belt. Newly acquired U-Pb geochronologic data of previously characterized sample suites provide a complete geologic history overview of the Sturgeon Lake greenstone belt. Ages were determined by separating zircon grains found within each plutonic sample, ablating each grain via Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), and measuring the abundances of radiogenic isotopes of U and Pb. Preliminary data reveal precise dates for multiple felsic plutons throughout the greenstone belt and further defines the magmatic and deformational history of the belt. Ongoing research also includes trace-element chemistry of the zircons to distinguish between the magmatic characteristics of mineralized and un-mineralized systems.