Otish Gabbros were emplaced into the Superior Province ca. 2172–2162 Ma.
Otish Gabbros are contemporaneous with the Biscotasing and Payne River swarms.
Group 1 Otish Gabbros approach liquid compositions. Group 2 gabbros are cumulates.
Ca. 2.17 Ga magmas reflect shallow melting of heterogeneous and enriched mantle.
Ca. 2.7 Ga mafic magmas were emplaced into thin lithosphere in a rifting environment.