Provenance approaches in polydeformed metasedimentary successions: Determining nearest neighboring cratons during the deposition of the Paleoproterozoic Murmac Bay Group

Abstract

The proximity and positions of cratons constituting the western Canadian Shield prior to and during the Rhyacian Period (2.30–2.05 Ga) are poorly known. In the absence of paleomagnetic data, stratigraphic correlation and detrital zircon isotopic data from sedimentary successions can be used to constrain relative craton positions during their time of deposition. The Murmac Bay Group, a multiply deformed metasedimentary succession located on the Rae craton margin in Canada, provides an opportunity to test hypotheses regarding its nearest cratonic neighbors during deposition. The polydeformed nature of the Murmac Bay Group, however, presents challenges in determining detailed stratigraphic relationships in the upper succession, which lacks distinct marker beds. Provenance analysis from detrital zircon geochronology provides one strategy for overcoming these challenges. Previous U-Pb geochronology indicates the lower succession was deposited 1.94 Ga. We provide new U-Pb detrital zircon ages for the upper succession, including a new maximum depositional age at 1.94 Ga). This provides an important constraint on the timing of Rae-Slave amalgamation.