RE-OS GEOCHRONOLOGY HIGHLIGHTS WIDESPREAD LATEST MESOPROTEROZOIC (CA. 1090-1050 MA) INTRACRATONIC BASIN DEVELOPMENT ON LAURENTIA

The amalgamation of Rodinia marks a period of widespread tectonic convergence in the terminal Mesoproterozoic. A brief window void of orogenesis between 1110–1090 Ma nearly saw the breakup of Laurentia at the Midcontinent Rift, but was interrupted by Grenvillian orogenesis on the eastern margin as the craton subducted underneath Amazonia. The Midcontinent Rift has been thought of as an isolated extensional phenomena ca. 1.1 Ga, but new depositional ages generated with the Re-Os geochronometer demonstrate that multiple intracratonic basins (Amundsen and Borden basins) were reactivating around this time on northern Laurentia. We present a Re-Os isochron from the Agu Bay Formation of the Fury and Hecla Basin (Arctic Canada) that is identical, within uncertainty, to that of shales from the Midcontinent Rift and Amundsen basins. Shale sedimentation in these basins collectively requires a broader tectonic driver to explain their synchronicity. We propose that rapid plate motion of Laurentia and widespread intracratonic magmatism were important mechanisms for what is now recognized to be a broad arc of tension on Laurentia between 1090-1050 Ma that was accommodated in multiple intracratonic basins on present-day central and northern North America.