Two komatiitic pyroclastic units, Superior Province, northwestern Ontario: their geology, petrography, and correlation

Two Archean komatiitic pyroclastic rock units occur on opposite sides of the Quetico Fault in northwestern Ontario. The eastern unit, the Dismal Ashrock, is located 3 km north of Atikokan, Ontario, on the north side of the Quetico Fault within the Wabigoon Subprovince of the Superior Province. It is part of a supracrustal sequence, the Steep Rock Group. The Grassy Portage Bay ultramafic pyroclastic rock unit (GUP) is located 100 km to the west, on the south side of the Quetico Fault, and is part of an overturned succession comprising mafic metavolcanic rocks, GUP, and metasedimentary rocks. Their metamorphism, deformation, petrography and geochemistry are described. -from Authors