Tectonic evolution of the Manitoba-Saskatchewan segment of the Paleoproterozoic Trans-Hudson Orogen, Canada

Abstract

Time slices and schematic cross-sections that attempt to show the spatial and temporal relationship between geological entities within the Manitoba–Saskatchewan segment of the Trans-Hudson Orogen and that are consistent with the available geological, geophysical, geochemical, isotopic, and geochronological data are presented. The Trans-Hudson orogenic belt developed as a result of closure of the Manikewan Ocean, which initially opened at about 2.1 Ga by rifting of a possible Neoarchean supercontinent. The oldest oceanic arc rocks indicate that subduction was ongoing by 1.92 Ga, with the development of a complex Manikewan "Ring of Fire" that lasted for the next 100 Ma. Intraoceanic accretion of arc, ocean-floor, and ocean-island rocks within the Manikewan Ocean at 1.87 Ga formed the Flin Flon – Glennie complex, which then subsequently collided with the accreted terranes along the Hearne craton margin at ca. 1.85 Ga. These rocks were then deformed and metamorphosed over the next 75 Ma during collisions with the Sask craton and the Superior craton, both of which are interpreted to have been drifting generally northwards towards the Hearne craton. The generation of arc magmas in the orogen ceased at 1.83 Ga, an indication that continental collisions were well advanced at that stage. The present arrangement and erosion level of geological entities is related to structural reorganization after the peak of regional metamorphism at ca. 1.81. The schematic time slices and sections form part of ongoing efforts to better understand the geological evolution of the Paleoproterozoic of Canada.