Geology and metallic mineralization of a representative klippe of the Bravo Lake Formation, Baffin Island, Nunavut

The stratigraphy, structural geology, metamorphism, and mineralizing environment of a type section of the Paleoproterozoic Bravo Lake Formation (BLF) of Baffin Island have been characterized in a well-exposed klippe. The klippe is in thrust contact with the underlying Longstaff Bluff Formation. Within the klippe, the BLF overlies sheared quartzite of the Dewar Lakes Formation which occurs immediately above the basal thrust fault. The Bravo Lake Formation comprises the following units: (1) a lower volcanic unit; (2) pillow basalt; (3) metasedimentary rocks intruded by ultramafic sills; (4) an upper volcanic unit; and (5) metasedimentary rocks containing iron-formation and laminated sulphide pods. Peak metamorphism, characterized by the mineral assemblage sillimanite + K-feldspar +/- muscovite +/- leucosome, indicates P-T conditions of 660 +/- 20°C, 3.5 +/- 0.3 kbar. Metamorphism postdates major fabric-forming deformation events. Metasedimentary units in the klippe contain exhalative massive sulphide and iron-formation, the latter containing local high-grade gold mineralization.