Tectonic evolution of the Paleoproterozoic Wollaston Group in the Cree Lake Zone, Northern Saskatchewan, Canada.

摘要

This thesis presents a comprehensive documentation of the geology and tectonic evolution of the Cree Lake Zone in the southwestern part of the Hearne Province, Saskatchewan, Canada. This zone consists of Neoarchean basement gneiss overlain unconformably by, and interfolded with, Paleoproterozoic paragneiss, both of which are intruded by plutonic rocks. Most of the supracrustal cover rocks belong to the regionally extensive Wollaston Group, although there are subordinate exposures of the rift-related Needle Falls Group. Rocks within the Cree Lake Zone were strongly reworked during the Paleoproterozoic Hudsonian orogeny.; The Wollaston Group comprises vertically and laterally variable lithologies, ranging from siliciclastic to calcareous and evaporitic deposits. Most of these were deposited in a back-arc to retro-arc foreland basin adjacent to a continental magmatic arc system. The make-up of sedimentary rocks reflects contrasting depositional environments from a post-rift, stable marginal setting, to a marine transgression, followed by regression and closure of the basin concomitant with uplift, unroofing, and cannibalization of older sedimentary and basement rocks in an active tectonic environment.; The Wollaston Group was affected by a number of Hudsonian thermotectonic events. The earliest event (D₁) produced predominantly thin-skinned structures in the Wollaston Domain and thick-skinned structures in the Mudjatik Domain. D₁ structures are typical of those in fold-thrust belts developed by tectonic inversion, and governed by original basement and sedimentary basin architecture. The second event (D₂) was represented by regionally non-cylindrical, en-échelon, doubly-plunging basement fold arrays. The third event (D₃) was characterized by northeast-trending folds that modified D₁/D₂ structures and accentuated regional structural grains.; The Cree Lake Zone appears to have evolved from a rifted continental margin to a foreland fold-thrust belt as outboard terranes collided with the Hearne cratonic margin, culminating with continent-arc and continent-continent collision. The Paleoproterozoic tectonic evolution of the Cree Lake Zone appears to have been exclusively related to the Hudsonian thermotectonism. (Abstract shortened by UMI.)