Paper No. 120-3
Presentation Time: 8:45 AM
RIDDLE OF RODINIA: PALEOMAGNETISM OF THE CHUAR GROUP AND EVALUATION OF THE 780-720 MA LAURENTIAN APPARENT POLAR WANDER PATH
During the Neoproterozoic Era (1000-541 Ma) the Earth experienced global glaciations, the diversification of crown group eukaryotes, and potentially a second great oxidation event, all of which are commonly associated with the breakup of the supercontinent Rodinia. However, both the paleogeography of Rodinia and the timing of continental separation remain poorly constrained. We report new paleomagnetic data from the 780-729 Ma Chuar Group of the Grand Canyon Supergroup, and refine the Laurentian apparent polar wander path through this critical interval to re-evaluate paleogeographic models for the makeup and breakup of Rodinia. The new poles are preserved in hematite and magnetite, and the primary nature of this paleomagnetic direction is supported by five of the seven Van der Voo (1990) reliability criteria. In addition to this primary direction, pervasive mid to high temperature overprints carried by hematite were identified. We incorporate these updated paleomagnetic poles with recent geochronological data and existing paleomagnetic data to present a new ca. 780-720 Ma Laurentian Apparent Polar Wander Path. Having examined the 780-720 Ma paleomagnetic database of other cratons, we present reconstructions for 780 Ma, 750 Ma and 720 Ma. Our new 780-720 Ma Laurentian apparent polar wander path is most consistent with a modified AUSMEX configuration, but we do not find an exact paleomagnetic match for the rifted margin from any major craton with constraints for 780-720 Ma.