Quench-textured, pillowed metabasalts and copper mineralization, Maybrun Mine, northwestern Ontario

CIM Bulletin, Vol. 76, No. 859, 1983

T. SETTERFIELD and D.H. WATKINSON, Department of Geology, Carleton University, Ottawa, Ontario, P.C. THURSTON, Ontario Geological Survey, Toronto, Ontario

The Maybrun copper deposit is in a succession of pillowed basaltic flows in the Wabigoon sub-province, northwestern Ontario. The rocks have primary flow morphologies and remarkably well-preserved crystallization textures, including quench-textured plagioclase, in spite of metamorphism to the amphibolite fades. The sulphide assemblage chalcopyrite-pyrrhotite-cubanite with minor sphalerite and pyrite is primarily in interpillow spaces and is stratabound. Basaltic rocks immediately enclosing the copper sulphide minerals have an enrichment in Fe, Mg and K and depletion in Ca and Na relative to surrounding flows. The Maybrun deposit is interpreted to have formed contemporaneously with volcanism and alteration, and was subsequently metamorphosed with the enclosing basalts.
Keywords: Economic geology, Maybrun Mine, Copper mineralization, Atikwa Bathoiith, Basalts, Metamorphism