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1. The Paleogeography of Laurentia in Its Early Years: New Constraints From the Paleoproterozoic East‐Central Minnesota Batholith

   https://doi.org/10.1029/2021TC006751  

   Swanson‐Hysell, Nicholas L.; Avery, Margaret S.; Zhang, Yiming; Hodgin, Eben B.; Sherwood, Robert J.; Apen, Francisco E.; Boerboom, Terrence J.; Keller, C. Brenhin; Cottle, John M. (May 2021, Tectonics)

   Abstract Theca. 1.83 Ga Trans‐Hudson orogeny resulted from collision of an upper plate consisting of the Hearne, Rae, and Slave provinces with a lower plate consisting of the Superior province. While the geologic record ofca. 1.83 Ga peak metamorphism within the orogen suggests that these provinces were a single amalgamated craton from this time onward, a lack of paleomagnetic poles from the Superior province following Trans‐Hudson orogenesis has made this coherency difficult to test. We develop a high‐quality paleomagnetic pole for northeast‐trending diabase dikes of the post‐Penokean orogen East‐Central Minnesota Batholith (pole longitude: 265.8°; pole latitude: 20.4°; A₉₅: 4.5°; K: 45.6 N: 23) whose age we constrain to be 1,779.1 ± 2.3 Ma (95% CI) with new U‐Pb dates. Demagnetization and low‐temperature magnetometry experiments establish dike remanence be held by low‐Ti titanomagnetite. Thermochronology data constrain the intrusions to have cooled below magnetite blocking temperatures upon initial emplacement with a mild subsequent thermal history within the stable craton. The similarity of this new Superior province pole with poles from the Slave and Rae provinces establishes the coherency of Laurentia following Trans‐Hudson orogenesis. This consistency supports interpretations that older discrepant 2.22–1.87 Ga pole positions between the provinces are the result of differential motion through mobile‐lid plate tectonics. The new pole supports the northern Europe and North America connection between the Laurentia and Fennoscandia cratons. The pole can be used to jointly reconstruct these cratonsca. 1,780 Ma strengthening the paleogeographic position of these major constituents of the hypothesized late Paleoproterozoic supercontinent Nuna. 

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2. Bayesian Paleomagnetic Euler Pole Inversion for Paleogeographic Reconstruction and Analysis

   https://doi.org/10.1029/2021JB023890  

   Rose, Ian R.; Zhang, Yiming; Swanson‐Hysell, Nicholas L. (October 2022, Journal of Geophysical Research: Solid Earth)

   Abstract Apparent polar wander paths (APWPs) synthesized from paleomagnetic poles provide the most direct data for reconstructing past paleogeography and plate motions for times earlier than ca. 200 Ma. In this contribution, we describe a new method for APWP synthesis that extends the paleomagnetic Euler pole analysis of Gordon et al. (1984,https://doi.org/10.1029/TC003i005p00499) by placing it within the framework of a Bayesian inverse problem. This approach incorporates uncertainties in pole positions and age that are often ignored in standard treatments. The paleomagnetic Euler poles resulting from the inversions provide estimates for full‐vector plate motion (both latitude and longitude) and associated uncertainty. The method allows for inverting for one or more Euler poles with the timing of changepoints being solved as part of the inversion. In addition, the method allows the incorporation of true polar wander rotations, thus providing an avenue for probabilistic partitioning of plate tectonic motion and true polar wander based on paleomagnetic poles. We show example inversions on synthetic data to demonstrate the method's capabilities. We illustrate application of the method to Cenozoic Australia paleomagnetic poles which can be compared to independent plate reconstructions. A two‐Euler pole inversion for the Australian record recovers northward acceleration of Australia in the Eocene with rates that are consistent with plate reconstructions. We also apply the method to constrain rapid rates of motion for cratonic North America associated with the Keweenawan Track of late Mesoproterozoic paleomagnetic poles. The application of Markov chain Monte Carlo methods to estimate paleomagnetic Euler poles can open new directions in quantitative paleogeography. 

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3. Paleomagnetic Records From Pulsed Magmatism in the Southwestern Laurentia Large Igneous Province and Cardenas Basalt Support Rapid Late Mesoproterozoic Plate Motion

   https://doi.org/10.1029/2024JB029036  

   Zhang, Yiming; Anderson, Nicolas_S; Mohr, Michael_T; Nelson, Lyle_L; Macdonald, Francis_A; Schmitz, Mark_D; Thurston, Olivia_G; Guenthner, William_R; Karlstrom, Karl_E; Swanson‐Hysell, Nicholas_L (October 2024, Journal of Geophysical Research: Solid Earth)

   Abstract Mafic intrusions, lava flows, and felsic plutons in southwestern Laurentia have been hypothesized to be associated with the emplacement of a late Mesoproterozoic (Stenian Period) large igneous province. Improved geochronologic data resolve distinct episodes of mafic magmatism in the region. The ca. 1,098 Ma main pulse of southwestern Laurentia large igneous province (SWLLIP) magmatism is recorded by mafic intrusions across southeastern California to central Arizona. A younger episode of volcanism resulted in eruptions that formed the ca. 1,082 Ma Cardenas Basalt, which is the uppermost unit of the Unkar Group in the Grand Canyon. With the updated geochronological constraints, we develop new paleomagnetic data from mafic sills in the SWLLIP. Overlapping poles between the Death Valley sills and rocks of similar age in the Midcontinent Rift are inconsistent with large‐scale Cenozoic vertical axis rotations in Death Valley. We also develop a new paleomagnetic pole from the ca. 1,082 Ma Cardenas Basalt (pole longitude = 183.9°E, pole latitude = 15.9°N,  = 7.4°,N = 18). The new paleomagnetic data are consistent with the pole path developed from time‐equivalent rocks of the Midcontinent Rift, supporting interpretations that changing pole positions are the result of rapid equatorward motion. These data add to the record of Laurentia's rapid motion from ca. 1,110 to 1,080 Ma that culminated in collisional Grenvillian orogenesis and the assembly of Rodinia. 

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4. Assessing plate reconstruction models using plate driving force consistency tests

   https://doi.org/10.1038/s41598-023-37117-w  

   Clennett, Edward J.; Holt, Adam F.; Tetley, Michael G.; Becker, Thorsten W.; Faccenna, Claudio (December 2023, Scientific Reports)

   Abstract Plate reconstruction models are constructed to fit constraints such as magnetic anomalies, fracture zones, paleomagnetic poles, geological observations and seismic tomography. However, these models do not consider the physical equations of plate driving forces when reconstructing plate motion. This can potentially result in geodynamically-implausible plate motions, which has implications for a range of work based on plate reconstruction models. We present a new algorithm that calculates time-dependent slab pull, ridge push (GPE force) and mantle drag resistance for any topologically closed reconstruction, and evaluates the residuals—or missing components—required for torques to balance given our assumed plate driving force relationships. In all analyzed models, residual torques for the present-day are three orders of magnitude smaller than the typical driving torques for oceanic plates, but can be of the same order of magnitude back in time—particularly from 90 to 50 Ma. Using the Pacific plate as an example, we show how our algorithm can be used to identify areas and times with high residual torques, where either plate reconstructions have a high degree of geodynamic implausibility or our understanding of the underlying geodynamic forces is incomplete. We suggest strategies for plate model improvements and also identify times when other forces such as active mantle flow were likely important contributors. Our algorithm is intended as a tool to help assess and improve plate reconstruction models based on a transparent and expandable set of a priori dynamic constraints. 

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5. Paleogeographic Reconstruction of the Paleozoic Lhasa Terrane Through Detrital Zircon Mixing Modeling

   https://doi.org/10.1029/2022GL100160  

   Xu, Wang; Hughes, Nigel C.; Liu, Lishuang; Zhang, Wen; Liu, Pinghua (November 2022, Geophysical Research Letters)

   Abstract A late Mesoproterozoic detrital zircon (DZ) age population, which was previously considered diagnostic of a link between the Lhasa terrane and northwest Australia, occurs in other Gondwanan components, thus obscuring the paleogeographic position of the Lhasa terrane in Gondwana. Here we compiled large‐n(n ≥ 300) DZ U‐Pb data from the Lhasa terrane and potential source regions in various proposed reconstructions, and attempted to synthesize the Lhasa DZ age spectra through DZ mixing modeling. Our modeling results support the Permo‐Carboniferous Lhasa terrane having received sediment from NW Australia (mainly the Perth basin) rather than India or Africa. This, in combination with stratigraphic and paleontological evidence from the northern margin of eastern Gondwana positions the Paleozoic Lhasa terrane adjacent to the boundary between Australia and India. This study suggests that the DZ mixing modeling method based on large‐nDZ data can be used effectively for constraining paleogeographic reconstruction of continents. 

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