From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

Abstract

We present a 169-km wide-angle velocity model across the Goban Spur rifted margin, southwest of the UK. A 120-km-wide intermediate region is identified between the first clear seafloor spreading magnetic anomaly (anomaly 34r) and thinned continental crust, where velocities increase from 4.5 km s -1 to 6.8 km s -1 in the top 4 km beneath acoustic basement. At depth it can be divided into a region where a 1.5-km-thick high-velocity layer (7.2-7.6 km s -1 ) exists and a region where this layer is absent but velocities of 7 km s -1 are present. Wide-angle PmP arrivals are observed across the whole of the intermediate region but a normal incidence reflection Moho is not present.