Tectonic evolution of southern Baffin Bay and Davis Strait: Results from a seismic refraction transect between Canada and Greenland

Abstract

Wide‐angle reflection/refraction seismic data were acquired on a 450‐km‐long transect in southern Baffin Bay extending from Baffin Island to Greenland. Dense air gun shots were recorded on 22 ocean bottom seismometers. APwave velocity model was developed from forward and inverse modeling of the observed travel times. Beneath the Baffin Island shelf, a three‐layered continental crust is observed with velocities of 5.5 to 6.9 km/s. Typical for transform margins, there is a sharp transition between continental and oceanic crust. Off Baffin Island, 7‐km‐thick oceanic crust is interpreted to lie in a major transform fault identified on the gravity map. Beneath the deep Baffin Bay basin, 9‐km‐thick oceanic crust is encountered but thins to 6 km within an assumed fracture zone. The thicker than normal oceanic crust indicates an ample magma supply, possibly related to melt extracted from a mantle plume. Seaward of the Greenland continental crust, 20‐km‐thick igneous crust (6.3 to 7.3 km/s) is encountered in a 25‐km‐wide zone interpreted as a leaky transform fault that can be correlated southward through Davis Strait. The igneous crust is bounded by a 20‐km wide basin to the west, underlain by 4‐km‐thick crust of unknown affinity. This structure is probably associated with transform movements. A high‐velocity lower crustal layer (7.1 km/s) of 8 km thickness is indicated beneath the Greenland crust and can be correlated into the adjacent thick igneous crust. Both the thick igneous and Greenland crust are covered by up to 4 km of Paleogene volcanics (5.2 to 5.7 km/s).

Tectonic variation and structural evolution of the West Greenland continental margin

“…............... 48 , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013. Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Bay, , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013. Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Densities were then calculated as a function of velocities using four different methods and in comparison with published data of , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013.…”

“…New COT boundaries have been interpreted based on multidisciplinary data integration of seismic reflection, refraction interpretation, gravity, magnetic 2D modelling and backstripping thermal subsidence modelling. ............... 48 , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013. Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Bay, , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013.…”

“…Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Bay, , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013. Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Densities were then calculated as a function of velocities using four different methods and in comparison with published data of , Funck et al (2007Funck et al ( , 2012, and Suckro et al (2012Suckro et al ( , 2013. Serpentinite zone from Nafe-Drake polynomial curve was interpreted in Baffin Bay, Figure 6.1: Regional tectonic framework of the west Greenland area generated by data integration of 2D seismic data (GEUS), structural provinces after Knutsen et al, (2012), seafloor data from Müller 2008, Global Seafloor Fabric and Magnetic chrons from Roest and Srivastava 1989;and Chalmers and Laursen (1995 shear-simple shear model (Lister et al, 1986), have described how crustal attenuation, followed by thermal subsidence and isostatic compensation have played the key roles in lithospheric and mantle geodynamics.…”

“…A 250 km long oceanic crust and c.6 to 9-km thick transition is estimated from a 450 km long seismic refraction . Other issues related to the geodynamic evolution of the Western Greenland margin include the presence of 20 km thick igneous crust underlain by 4 km thick layer of unknown affinity and the tectonic significance of the Ungava transform fault zone (Funck et al, 2007;Funck et al, 2012). On the northern Baffin Bay, the transition zone to oceanic crust is characterised by a high gravity anomaly and magnetic anomalies dated as Eocene at N27-25N and 24N-13N (Whittaker et al, 1997;Oakey and Chalmers, 2012).…”

“…The evolution of West Greenland during continental breakup is controversial. Diverse opinions centre on the timing of uplift, on the number of phases of extrusive volcanism, on the initiation of rifting, sea-floor spreading and geotectonic development of the region during the continental breakup (Korstgärd and Nielsen, 1989;Storey et al, 1998;Larsen et al, 2009;Funck et al, 2012;Oakey and Chalmers 2012;Suckro et al, 2013).…”