Margin segmentation of Baffin Bay/Davis Strait,eastern Canada based on seismic reflection and potential field data

摘要

The continental margin of Baffin Island was interpreted from a compilation of seismic reflection and potential field data.Based on these data,it was divided into volcanic and non-volcanic segments.In the northernmost area,coast-parallel grabens and continental basement highs are superseded beneath the slope by irregular basement topography.In combination with the velocities from refraction data and the lack of a magnetic slope anomaly,we propose a non-volcanic margin.In the central region,the seismic data show a limited region with a seaward dipping reflector sequence that may be intercalated with a sedimentary section.Both north and south of Cape Dyer extensive volcanic rocks are interpreted at and below seabed consistent with a volcanic margin.In the southern region,the depth to basement drops rapidly offshore.A thick prograding sedimentary wedge produces a high-amplitude long-wavelength free-air gravity anomaly that was previously confused with the continent-ocean boundary.Although some volcanic rocks are mapped in the region,this area is adjacent to the non-volcanic Labrador Sea margin and is interpreted to be of similar structure.Segmentation of the margin by major faults can explain the abrupt transitions from volcanic to non-volcanic margin segments.The continent-ocean boundary for the region is determined based on the potential field and seismic data.Along the Greenland plate in Davis Strait the continent-ocean boundary coincides with the Ungava Fault Zone.The continent-ocean boundary is used in conjunction with published poles of rotation to evaluate plate reconstructions at chrons 33n and 27n.The earlier reconstruction produces an extensive overlap of boundaries in the north.The later reconstruction shows a gap in the southern region.Thus,additional information is required to refine the reconstructions.