An integrated U-Pb, Hf, and O isotopic provenance analysis of the Paleoproterozoic Murmac Bay Group, northern Saskatchewan, Canada

Abstract

Sedimentary successions deposited near craton margins provide an opportunity to test hypotheses regarding nearest cratonic neighbors during deposition by reconstructing their sedimentary provenance. The Paleoproterozoic Murmac Bay Group, northern Saskatchewan, Canada, was deposited near the southwestern margin of the Rae craton between 1.93Ga and 2.32Ga. We present the first integrated detrital zircon U-Pb geochronology, Lu-Hf, and O isotope analysis of detrital zircon from these rocks with the aim to elucidate provenance and characterize crustal growth in the source regions. A foreland tectonic setting associated with the Taltson orogeny has been suggested for the upper Murmac Bay Group paleobasin, however its sediment source(s) remain uncertain. Our Hf data show that not all zircon U-Pb age populations can be attributed to local (Rae craton) sources. Integrating U-Pb, Lu-Hf, and O isotope data, we find that the most probable source rocks, in addition to Rae craton rocks, were from the Buffalo Head-Chinchaga domains in northern Alberta. Hafnium model ages calculated from the upper Murmac Bay Group identify two periods of regional crustal growth at 2.83Ga and 2.70Ga, agreeing with Sm-Nd model ages from the western Churchill province.