Geochemical, Isotopic, and Mineralogical Characterization of the Frobisher Suite Mafic-Ultramafic Sills, Southern Baffin Island, Nunavut, with Implications for Metallogenic Potential

The Frobisher Suite is a newly recognized magmatic province comprised of mafic-ultramafic sills in southern Baffin Island, Nunavut. The sills are emplaced into the metasedimentary strata of the middle Paleoproterozoic Lake Harbour Group, and vary in thickness from several meters to hundreds of meters. Based on major and trace element chemistry, the Frobisher Suite can be divided into eight geochemical groups. The major geochemical components indicate melting occurred to differing degrees within a mantle plume head, at various depths below the Meta Incognita microcontinent at ca. 1900 Ma. A number of sills formed via injections of multiple, distinct magma types, some of which were influenced by subcontinent lithospheric mantle. Disseminated sulphides are present in the sills, and in some cases, the adjacent host psammite. At this stage, the Frobisher Suite may be considered to be part of its own Large Igneous Province (LIP), termed the “Frobisher LIP.”