Paleomagnetic evidence for a large rotation of the Yukon Block relative to Laurentia; implications for a low-latitude Sturtian glaciation and the breakup of Rodinia

Understanding the tectonic history of the supercontinent Rodinia is crucial for testing proposed links among Neoproterozoic tectonics, supercontinent cycles, climate, and biogeochemistry. The Neoproterozoic Mount Harper volcanics of the Ogilvie Mountains, Yukon, Canada, interfinger with Sturtian-age (ca. 717-660 Ma) glacial deposits that were deposited in narrow, fault-bounded basins related to the breakup of Rodinia. Here, we present new paleomagnetic data from the Mount Harper volcanics and isolate four paleomagnetic directions: a low-temperature direction recording the present geomagnetic field, a mid-temperature direction consistent with a Cretaceous overprint, and two high-temperature directions, one of which is carried by hematite and likely represents a chemical overprint, and the other of which is carried by magnetite and likely is a primary direction. This primary pole passes the fold and conglomerate tests and includes a reversal but is 50 degrees away from the coeval 721-712 Ma Laurentian Franklin large igneous province pole. This difference can be reconciled using a 50 degrees counterclockwise rotation of the Yukon block relative to Laurentia. The prerotation reconstruction of the Yukon block relative to Laurentia aligns Neoproterozoic fault orientations and facies belts between the Wernecke and Mackenzie Mountains, rectifies paleoflow measurements in Mesoproterozoic and Paleoproterozoic strata, and realigns the orientation of the ca. 1260 Ma Bear River dikes with the Mackenzie dike swarm of northern Canada. This reconstruction also facilitates future studies that relate Neoproterozoic sedimentary and structural patterns to the fragmentation of Rodinia. Finally, this low-latitude pole supports the snowball Earth interpretation of the ca. 717 Ma Sturtian glacial deposits.