Preliminary Investigations of Early Proterozoic western River and Burnside River Formations : Evidence For Foredeep Origin of Kilohigok Basin, District of Mackenzie

Abstract

In the Kilohigok Basin, the Western River and Burnside River formations comprise three successively overlying tectono-stratigraphic sedimentary units of regional extent: a basal shallow water siliciclastic/carbonate platform, overlain by deepwater flysch, in turn overlain by shallow marine and fluvial molasse. This stratigraphy represents an initial stable shelf (passive margin?) whose outer, southerly edge rapidly subsided contemporaneous with arching and subaerial exposure of its interior. Shelf drowning represents the onset of foredeep subsidence subparallel to the trend of Thelon Tectonic Zone. Arching and subsidence were perpendicular to the tectonic transport direction of intrabasinal nappes. indicating that convergence and uplift a long Thelon Tectonic Zone were probably responsible for foredeep subsidence within Ki lohigok Basin. Following drowning, the platform was buried by deepwater deposits ( flysch); with progressive uplift and basin filling, the foredeep entered the molasse phase and fluvial sediments prograded towards the foreland. The foredeep model places constraints on the origin of Thelon Tectonic Zone and provides a more comprehensive understanding of the tectonic evolution of the Slave Province and its relation to the Wopmay Orogen.