The Corrugated Hills Continental Flood Basalt: a ca. 2.17 Ga flood basalt province related to breakup of the Superior craton

Abstract This study documents a major continental flood basalt province in the central Labrador Trough that produced voluminous mafic magmatism along the paleo-rifted margin of the Superior craton. This area, representing a preserved magma volume of approximately 25,000 km 3 , is characterized by classic ‘traps’ topography with columnar-jointed flows and sills separated by thin clastic sedimentary layers. A gabbroic sill near the bottom of the sequence yielded a U-Pb zircon age of 2166 ±4 Ma, and another near the middle of the sequence yielded a 2171 ±3 Ma U-Pb zircon age. These ages overlap in time with published ages of mafic dyke swarms that radiate outwards into the adjacent Superior craton, namely the Biscotasing (2172-2167 Ma) and Payne River (2170-2160 Ma) dykes, as well as the Otish sills (2172-2162 Ma) and Tasiataq (2170 Ma) dyke. Our data suggest that these central Labrador magmas, named the “Corrugated Hills Continental Flood Basalt” were emplaced near or above a mantle plume head, leading to thermal uplift and then rifting of the Superior craton margin. Field relationships suggest that these magmas were erupted through thinned Archean crust as a rift-related continental flood basalt suite. The Corrugated Hills Continental Flood Basalt province represent remnants of one of the oldest continental flood basalt provinces on Earth.