The late Mesoproterozoic to early Neoproterozoic Grenvillian orogeny and the assembly of Rodinia: Turning point in the tectonic evolution of Laurentia

Abstract

The amalgamation of Laurentia’s Archean provinces ca. 1830 Ma was followed by ~700 m.y. of accretionary orogenesis along its active southeastern margin, marked by subduction of oceanic lithosphere, formation of arcs and back-arcs, and episodic accretion. This prolonged period of active-margin tectonic processes, spanning the late Paleoproterozoic and Mesoproterozoic eras, resulted in major accretionary crustal growth and was terminated by closure of the Unimos Ocean (new name). Ocean closure was associated with rapid motion of Laurentia toward the equator and resulted in continental collision that led to profound reworking of much of the accreted Proterozoic crust during the ca. 1090–980 Ma Grenvillian orogeny. The Grenvillian orogeny resulted in formation of a large, hot, long-duration orogen with a substantial orogenic plateau that underwent extensional orogenic collapse before rejuvenation and formation of the Grenville Front tectonic zone. The Grenvillian orogeny also caused the termination and inversion of the Midcontinent Rift, which, had it continued, would likely have split Laurentia into distinct continental blocks. Voluminous mafic magmatic activity in the Midcontinent Rift ca. 1108–1090 Ma was contemporaneous with magmatism in the Southwestern Laurentia large igneous province. We discuss a potential link between prolonged subduction of oceanic lithosphere beneath southeast Laurentia in the Mesoproterozoic and the initiation of this voluminous mafic magmatism. In this hypothesis, subducted water in dense, hydrous Mg-silicates transported to the bottom of the upper mantle led to hydration and increased buoyancy, resulting in upwelling, decompression melting, and intraplate magmatism. Coeval collisional orogenesis in several continents, including Amazonia and Kalahari, ties the Grenvillian orogeny to the amalgamation of multiple Proterozoic continents in the supercontinent Rodinia. These orogenic events collectively constituted a major turning point in both Laurentian and global tectonics. The ensuing paleogeographic configuration, and that which followed during Rodinia’s extended breakup, set the stage for Earth system evolution through the Neoproterozoic Era.

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

“…The paleogeographic positions of conjugate continents to Laurentia long the Grenville margin in the reconstructions follow the interpretation of Swanson‐Hysell et al. (2023). The inset figure compares Laurentia's position predicted by the new Jacobsville paleomagnetic pole (red) and that constrained by the Haliburton intrusions of the Grenvillian orogeny (light blue) which has been assigned an age of 1,015 Ma (Warnock et al., 2000)).…”

“…While this calcite date has large analytical uncertainty, it indicates that the fault breccia developed associated with the Grenvillian orogeny and it overlaps with the ca. 1,010–980 Ma ages of metamorphism associated with the Rigolet phase of the orogeny (Swanson‐Hysell et al., 2023). It is during this ca.…”

“…Subsequently, the rift was inverted as contraction associated with the ca. 1,090–980 Ma Grenvillian Orogeny on the eastern margin of Laurentia (Figure 1) propagated into Laurentia's interior (Cannon, 1994; Cannon et al., 1993; Hodgin et al., 2022; Swanson‐Hysell et al., 2023).…”

Bayesian Paleomagnetic Euler Pole Inversion for Paleogeographic Reconstruction and Analysis

“…Overall, forward models involving small circle Euler rotations yield better fits to the observed paleomagnetic data than the model that considers only true polar wander great circle rotation (Figure 8). These results indicate that there was rapid plate motion at the time which is associated with subduction that led to the closure of the Unimos Ocean leading up to collisional Grenvillian orogenesis and the associated formation of the supercontinent Rodinia (Hynes & Rivers, 2010; Swanson‐Hysell et al., 2022). In comparison with models that involve one Euler pole rotation, the two Euler pole inversion results in an improvement in fit as can be visualized by the modeled pole positions shown in Figure 9a and by the calculated posterior likelihood distributions for the paleomagnetic pole positions (Figure 8b).…”

Joint Inversion of SPREE Receiver Functions and Surface Wave Dispersion Curves for 3‐D Crustal and Upper Mantle Structure Beneath the U.S. Midcontinent Rift

“…The MCR's intersection with the Superior Craton is a defining area within which to study rift inception and demise. An alternative explanation of the development of the MCR is presented by Swanson-Hysell et al (2023), who connect prolonged subduction of oceanic lithosphere beneath southeast Laurentia in the Mesoproterozoic with the initiation of voluminous mafic magmatism of the MCR via a deep mantle water cycle. They proposed that dense hydrous minerals subducted to the bottom of the upper mantle before dehydrating and initiating upwelling, decompression melting, and intraplate magmatism.…”