GAC Howard Street Robinson lecturer David Corrigan - The Archean-Proterozoic transition and emergence of modern-type plate tectonics

The Archean-Proterozoic transition between ca. 2.5 and 1.8 billion years ago was characterized by fundamental transformations in the scale and style of plate tectonics, introducing, for the first time in Earth’s history, processes that more closely resembled those found in modern environments. These processes include continental margin rifting and eruption of continental flood basalt, establishment of passive continental margins, arc and back-arc magmatism, generation of supra-subduction zone ophiolites, as well as accretion of juvenile terranes and micro-continents. Elements of modern-type continent-continent collision also emerged, such as indentation tectonics, formation of oroclines, as well as deep exhumation of continental crust and escape tectonics. This lecture focuses on the Trans-Hudson orogen, which has preserved a ~ 270 m.y. long, near-complete record of ocean opening, closure, accretion, and collision spanning from Saskatchewan to the North Atlantic coast and beyond. We will also see how thick, cold sub-continental lithospheric keels acquired during the Archean played a role in subsequent tectonics and preservation of continental crust.