Paleomagnetism of the Chuar Group and evaluation of the late Tonian Laurentian apparent polar wander path with implications for the makeup and breakup of Rodinia

Abstract

Paleogeographic models commonly assume that the supercontinent Rodinia was long-lived, with a static geometry involving Mesoproterozoic links that developed during assembly and persisted until Neoproterozoic rifting. However, Rodinian paleogeography and dynamics of continental separation around its centerpiece, Laurentia, remain poorly constrained. On the western Laurentian margin, geological and geochronological data suggest that breakup did not occur until after 720 Ma. Thus, late Tonian (ca. 780–720 Ma) paleomagnetic data are critical for reconstructing paleogeography prior to dispersal and assessing the proposed stasis of Rodinia. Here, we report new paleomagnetic data from the late Tonian Chuar Group in the Grand Canyon, Arizona. We combined this new data set with reanalyzed existing data to obtain a new paleopole preserved in hematite, the reliability of which is supported by six of the seven (Q1–Q6) Van der Voo reliability quality criteria. In addition, we identified pervasive mid- to high-temperature overprints. This new paleomagnetic pole was incorporated with recent high-precision geochronological data and existing paleomagnetic data to present a new late Tonian Laurentian apparent polar wander path (APWP). Having examined the paleomagnetic data of other cratons, global reconstructions for 775 Ma, 751 Ma, and 716 Ma are presented. These reconstructions are consistent with Australia located near the present southern margin of Laurentia. However, a stringent analysis of the global data set does not support a good match between any major craton and the rifted conjugate margin to western Laurentia. Breakup on the western Laurentian margin may have involved rifting of a continental fragment or a craton with uncertainties in its late Tonian geochronologic and paleomagnetic constraints. Our revised Laurentian APWP will allow for more robust tests of paleogeography and evaluation of the proposed supercontinent Rodinia.

Geologic evidence for an icehouse Earth before the Sturtian global glaciation

“…This stratigraphic relationship also implies that the paleomagnetic record from Laurentia may be used to constrain the depositional paleolatitude of the overlying Neoproterozoic sedimentary rocks. Multiple paleomagnetic studies robustly constrain eastern Laurentia (modern eastern and central United States) to low latitudes for most of the Tonian (21)(22)(23)(24)(25).…”

Evaluating the Shinumo-Sespe drainage connection: Arguments against the “old” (70–17 Ma) Grand Canyon models for Colorado Plateau drainage evolution

“…For example, any of the orthoquartzites could have been remagnetized in the Late Cretaceous to Cenozoic in the Maria fold and thrust belt, core complexes, or Death Valley regions to give moderate secondary inclinations similar to today's magnetic field. For example, samples from Neoproterozoic-Cambrian sandstones from Grand Canyon and the Uinta Mountains have been completely remagnetized with steep recent chemical remanent magnetizations carried by hematite (Weil et al, 2004(Weil et al, , 2006Eyster et al, 2020). Some of the Zijderveld diagrams from these remagnetized samples (Eyster et al, 2020) look similar to those depicted as primary in Sabbeth et al (2019).…”

“…For example, samples from Neoproterozoic-Cambrian sandstones from Grand Canyon and the Uinta Mountains have been completely remagnetized with steep recent chemical remanent magnetizations carried by hematite (Weil et al, 2004(Weil et al, , 2006Eyster et al, 2020). Some of the Zijderveld diagrams from these remagnetized samples (Eyster et al, 2020) look similar to those depicted as primary in Sabbeth et al (2019). Hence, it is possible that some of the Sespe clasts could include a primary direction carried by magnetite (or lower-coercivity hematite) and then a steep overprint carried by high-coercivity hematite (Sabbeth et al, 2019; their supplementary figure S2).…”

Extending full-plate tectonic models into deep time: Linking the Neoproterozoic and the Phanerozoic

“…At this time, palaeomagnetic data from the Baltica (Walderhaug et al, 2007) suggest that Rodinia had drifted to southerly latitudes, before returning to equatorial latitudes by ca. 750 Ma (Eyster et al, 2019). MER17 modelled significant relative dextral motion between Congo-SF-Azania and Rodinia during this time (870-750 Ma) as well, as suggested by palaeomagnetic data (Evans et al, 2016).…”

“…Fig. 14f, g Macdonald et al, 2013) (see also Colpron et al, 2002;Cox et al, 2018;Eyster et al, 2019). Mulder et al (2018b), while the Ediacaran-Cambrian evolution is after Mulder et al (2020).…”