U-Pb zircon constraints on the timing and provenance of fluvial sedimentary rocks in the Flin Flon and Athapapuskow basins, Flin Flon Domain, Trans-Hudson Orogen, Manitoba and Saskatchewan

Abstract

Fluvial sedimentary rocks of the Missi Group in the Paleoproterozoic Flin Flon Domain, Manitoba and Saskatchewan, which unconformably overlie Amisk island-arc and ocean-floor volcanic rocks, were likely deposited in basins that developed as a result of crustal thickening during early arc-continent collisions in the Trans-Hudson Orogen. U-Pb analyses of detrital zircons from the Flin Flon and Athapapuskow basins, yielded ages that tightly constrain the timing of sedimentation, and provide information on the age of the source region. The Flin Flon Basin is intruded by Boundary Intrusions, with a published U-Pb age of 1842 +/- 3 Ma. The youngest detrital zircon has a concordant U-Pb age of 1847 +/- 2 Ma, indicating that Missi sedimentation in the Flin Flon Basin occurred between 1847 and 1842 Ma. U-Pb ages of 1848 +/- 2 and 1846 +/- 6 Ma yielded by zircons from the Athapapuskow Basin suggests that sedimentation in the two basins was likely synchronous. The range in zircon ages suggests that much of the detritus was derived locally from granitoids and Amisk volcanic rocks. However, 207Pb/206Pb zircon ages of 2431, 2473, and 2494 Ma from the Flin Flon Basin, and 2708 and 2721 Ma from the Athapapuskow Basin indicate that Early Paleoproterozoic/Archean terranes were exposed at the time of Missi Formation sedimentation.