Plate tectonics before 2.0 Ga: Evidence from paleomagnetism of cratons within supercontinent Nuna

Abstract

Laurentia, the core of Paleo- to Mesoproterozoic supercontinent Nuna, has remained largely intact since assembly 2.0 to 1.8 billion years ago [Ga]. For earlier times, previous paleomagnetic data on poorly dated Paleoproterozoic mafic intrusions yielded ambiguous estimates of the amount of separation between key cratons within Nuna such as the Slave and Superior. Recent developments in paleomagnetism and U-Pb baddeleyite geochronology, including new results reported herein, yield sufficiently precise data to generate partial apparent polar wander paths for both the Slave and Superior craton from 2.2 to 2.0 Ga. Our new apparent polar wander comparison confirms earlier speculations that processes similar to plate tectonics, with relative motion between the Slave and Superior cratons, were operative leading up to the final assembly of supercontinent Nuna.