U-Pb zircon geochronology of early Proterozoic Wopmay Orogen, N.W.T. Canada: an example of rapid crustal evolution

U-Pb zircon data for more than 50 major igneous and sedimentary units within Wopmay Orogen tightly constrain magmatic and tectonic activity during its development. Intrusive and extrusive felsic prophyries in Akaitcho Group provide a minimum age of 1900 Ma for initial rifting. Analyses of detrital zircons from Arkosic sedimentary rocks within Akaitcho Group indicate two main provenance ages, greater than or equal to2.7 Ga and 2.05 Ga. Exposed basement to the passive margin ranges from 2.5 to 3.5 Ga. Hepburn Intrusive Suite plutons were emplaced about 1.885 Ma, constraining deposition and collision of the passive margin to less than 15 million years. Detrital zircons from metasedimentary rocks in Hottah Terrane yield source ages of 2.1 to 2.3 Ga. Deformed granitoid plutons that intrude Hottah Terrane metasedimentary units range from 1.902 to 1.914 Ga. Volcanic and sedimentary rocks of Great Bear Magmatic Zone unconformably overlie deformed Hottah Terrane granites to the west and Archean basement to the east. The major pulses of Great Bear volcanism and plutonism occurred between 1.875 and 1.860 Ga and were followed by folding NW-trending axes and intrusion of high-K granites (1.85 to 1.84 Ga). An exposure of basement within the Great Bear Magmatic Zone 20 km west of Wopmay Fault Zone has an age of 1930 Ma, suggesting that the suture between Hottah Terrane and Coronation Margin lies in between. Terminal collision west of Hottah Terrane is manifested by conjugate transcurrent faults that post-date a 1.84 Ga pluton and pre-date 1.67 Ga Narakay Volcanic Complex in the post-orogenic Hornby Bay Group