The tectonic history of southern Baffin Bay and Davis Strait - seismic refraction experiments and the evolution of oceanic crust

Located between the Canadian Baffin Island and Greenland, Baffin Bay represents the northern extension of the rift system in Labrador Sea. Davis Strait is a bathymetric high, that connects Baffin Bay with the Labrador Sea and acts as a gateway for the water exchange between the two basins. The strait is dominated by the Ungava Fault Complex, a major transform fault, characterized by a series of positive gravity anomalies. It is generally agreed, that the extensional motion of the rift system in Labrador Sea was connected with the opening of Baffin Bay by the Ungava Fault Complex. Unlike in Labrador Sea, no magnetic spreading anomalies have clearly been identified in Baffin Bay, hence the nature of the crust remains a subject of discussion. In order to determine the character of the crust in southern Baffin Bay, a 710-km-long seismic refraction experiment was set up in two research cruises (MSM09/3 of RV Maria S. Merian in 2008 and ARK25/3 of RV Polarstern in 2010). P-wave velocity and density modeling display the following crustal units from southeast to northwest: transitional crust near Baffin Island, more than 300 km of oceanic crust with an extinct spreading center, 100 km of transitional crust of a volcanic type margin on the Greenland side of the profile, and Greenland continental crust. The nature of the crust in Davis Strait is also disputed. Both, blocks of continental crust or a thick pile of oceanic crust have been proposed. To identify the character of the crust, a 226-km-long seismic refraction line was set up across the strait (MSM09/3 expedition). The P-wave velocity and density models image continental blocks with deep reaching faults. The lower crust displays abnormally high P-wave velocities, which we attribute to intense intrusions of mafic material, most likely related to the arrival of the Iceland mantle plume beneath Greenland in the Paleocene. To set the crustal units along the two profiles into context with the tectonic history of the Labrador Sea and Baffin Bay region, we visualized the opening of these basins in GPlates with published poles of rotation. It became clear, that the existing tectonic map of this region needs modifications, which we present here. Furthermore, the reconstruction images the compression of previously rifted crust in Davis Strait which adds up to an overlap of 70 km.