Re-Os geochronology highlights widespread latest Mesoproterozoic (ca. 1090–1050 Ma) cratonic basin development on northern Laurentia

Abstract

The terminal Mesoproterozoic was a period of widespread tectonic convergence globally, culminating in the amalgamation of the Rodinia supercontinent. However, in Laurentia, long-lived orogenesis on its eastern margin was punctuated by short-lived extension that generated the Midcontinent Rift ca. 1110–1090 Ma. Whereas this cratonic rift basin is typically considered an isolated occurrence, a series of new depositional ages demonstrate that multiple cratonic basins in northern Laurentia originated around this time. We present a Re-Os isochron date of 1087.1 ± 5.9 Ma from organic-rich shales of the Agu Bay Formation of the Fury and Hecla Basin, which is one of four closely spaced cratonic basins spanning from northeastern Canada to northwestern Greenland known as the Bylot basins. This age is identical, within uncertainty, to ages from the Midcontinent Rift and the Amundsen Basin in northwestern Canada. These ages imply that the late Mesoproterozoic extensional episode in Laurentia was widespread and likely linked to a common origin. We propose that significant thermal anomalies and mantle upwelling related to supercontinent assembly centered around the Midcontinent Rift influenced the reactivation of crustal weaknesses in Arctic Laurentia beginning ca. 1090 Ma, triggering the formation of a series of cratonic basins.

Far from boring: A new Grenvillian perspective on Mesoproterozoic tectonics

“…1) and the Southwestern Large Igneous Province 23 were major ma c magmatic events that required signi cant extension of the crust from 1.15 to 1.08 Gyr-ago 24 . Synchronously, major sedimentary basins were created by rifting 25 more than 3000 km towards the hinterland (Fig. 1).…”

“…Laurentia was thus a passive margin throughout most of the Mesoproterozoic, with access to sea water such as documented in sedimentary rocks of the MCR 26,27 . The extremely fast motion of Laurentia between 1.1 and 1.08 Gyr-ago dragged by slab avalanche, would likely have put the entire continent under extension and generated all the major sedimentary basins and large igneous province such as the MCR that formed during this period 24,25 . Moreover, our model better reconciles proxies of tectonic activities used to infer tectonic quiescence during the so-called "boring billion".…”

Tracking Rodinia Into the Neoproterozoic: New Paleomagnetic Constraints From the Jacobsville Formation

“…1,070 Ma (Henry et al., 1977; Slotznick et al., 2023). While there are some contemporaneous basins in northern Laurentia (Greenman et al., 2021), there is minimal basin development within Laurentia following the Grenvillian orogeny until the Rodinia supercontinent began to rift apart ca. 770 Ma (Macdonald et al., 2023).…”