Diversity of the crustal structure in the northern Baffin Bay and the southern Nares Strait

Abstract

The crustal structure of the Baffin Bay and southern Nares Strait is studied based on three refraction seismic profiles and corresponding reflection- and gravity datasets. P wave velocity, density and geological models derived from raytracing, modeling and interpretation of these datasets are presented. My findings confirm that a 3.5-7 km thick oceanic crust is present in central northern Baffin Bay, which is covered by up to 6.5 km thick sediments. The partly small thickness of the crust and the underlying serpentinized upper mantle are indications for slow to ultraslow spreading rates during the formation of the oceanic crust. An up to 80 km wide continent-ocean transition zone separates the oceanic crust from stretched and rifted continental crust. The continent-ocean transition in the Melville Bay area has been affected by intrusive and extrusive magmatism, while the transition between continental and oceanic crust in the southern Nares Strait does not show any signs of magmatic activity. Therefore, the margin in the southern Nares Strait can be classified as non-volcanic rifted margin. The margin west of the Melville Bay area can be described as rifted margins with decreasing influence of magmatism towards the north, since clear indications for a classification as non-volcanic or volcanic margins are missing. The up to three-layered crystalline continental crust has a maximum thickness of 30 km and is partly covered by sediments. Steep faults and deep basins characterize the Melville Bay area. Two parallel extending profiles in northern and southern Melville Bay revealed changes in the crustal geometry as well as in basin infill and therefore indicate differences in the genesis of both regions. A comparison of my results on the extent of crustal types in the research area with previous studies shows that the extent of the continent-ocean transition and partly also the eastern extent of oceanic crust were underestimated in the northeastern Baffin Bay.