Cenozoic Relative Movements of Greenland and North America by Closure of the North Atlantic-Arctic Plate Circuit: The Labrador Sea, Davis Strait, Baffin Bay, and Eurekan Orogen

Abstract

Cretaceous to earliest Oligocene plate motions between Greenland and North America can only be directly modelled at high resolution from a short duration (61-42 Ma) sequence of magnetic isochrons in the Labrador Sea. Understanding those motions at other times is hampered by interpretational conflicts and the low or variable resolutions of geoscientific observations from west and north of Greenland. To better contextualize these observations, we build and manipulate models of North America-Eurasia and Eurasia-Greenland divergence and combine them to derive 13 new rotations that depict post-84 Ma North American-Greenland motions at unprecedented high temporal resolution. The rotations show that magnetic anomalies landwards of isochron C26 in the Labrador Sea cannot be related to magmatic crustal accretion at a focussed mid-ocean ridge. They also show how the North American-Eurasian plate boundary propagated northwards, leading to continental breakup in the Labrador Sea by $\sim$90 Ma and Baffin Bay by $\sim$68-65 Ma, perhaps in response to an increased supply of melt from the Iceland plume. We also show how field evidence for the Eurekan orogeny having occurred in distinct phases can be directly relatable to changes in Greenland-North American plate motion parameters over the 63-33 Ma period.