Deep seismic reflection data across the conjugate margins of the Labrador Sea

A deep seismic reflection transect of the conjugate margins of the Labrador Sea is described, which represents one of the few data sets of this kind. A characteristic reflectivity is ascribed to a 120 km wide ribbon of very thin crust that may be either thinned continental crust, which has perhaps been intruded, or oceanic crust, perhaps modified by the proximity of the continent. Most of the major changes in crustal thickness and in the subsidence and sedimentation patterns on the margins occur landward of these transitional zones, which are found on both margins. An interpretation of these regions as continental in origin is compatible with other seismic observations on the west Greenland margin, but does not match the magnetic anomaly interpretation, which requires the transitional crust to be oceanic in origin. Models that satisfy the gravity anomalies and the subsidence history have been used to assist in interpreting the seismic data. The subsidence models include the effects of decompression meltin...