THE PALEOGEOGRAPHY OF NORTHERN ALASKA: KNOWNS AND UNKNOWNS

The northernmost Cordilleran orogen in Alaska has an incredibly complex and poorly understood geologic history that is exacerbated by a lack of paleomagnetic data. Here, we review all of the published paleomagnetic data from Northern and Interior Alaska, including new data from the northern Brooks Range. Though it was previously believed that regional metamorphism has destroyed all pre-Cretaceous paleomagnetic directions in this region, this is not the case. We find that paleomagnetic poles from as early as the Franklin large igneous province (720 Ma) are preserved, and most igneous units in the region retain a primary remanence. Based on our compilation, some popular tectonic models of northern Alaska (e.g., counterclockwise rotation of Arctic Alaska during the opening of the Canada Basin) are not well supported by the existing paleomagnetic data. Despite this, our review makes it apparent that the paleogeography of this vast region cannot be confidently reconstructed prior to the Mesozoic, due to the dearth of paleomagnetic studies; however, tectonic reconstructions based on the published paleomagnetic data from the Jurassic-present have interesting tectonic implications for much of the Arctic and northern Cordillera. Future coupled paleomagnetic and tectonic/structural studies in northern Alaska could be significantly impactful.