Chris Couëslan 

Precambrian Geologist
Manitoba Geological Survey

Stratigraphy and implications for magmatic Ni-Cu deposits in the HalfwayLake area, Thompson Nickel Belt, Manitoba

A revised stratigraphy for the Halfway Lake area has been compiled based on field mapping and logging of archived industry and government drillcore. Ospwagan group stratigraphy, including Thompson, Pipe, and Setting formations along with Bah Lake assemblage volcanic rocks are present. A sheared unconformity separates the Ospwagan group rocks from the underlying Archean basement. The stratigraphy was deformed into a series of regional, upright and attenuated, isoclinal F3 folds. Ultramafic rocks occur near the Thompson formation–Pipe formation transition and are locally in close spatial association with sulphidic rocks that correlate with the ore horizon at Thompson mine. The ultramafic rocks are locally mineralized and have been the focus of previous exploration activities. A similar structural regime as that of the Thompson mine area implies that exploration efforts targeting F3 fold structures for thickened zones of sulphide in hinge zones, and mineralization hosted by metasedimentary rocks rather than by intrusions, could be viable strategies in the Halfway Lake area.