Orphan Basin crustal structure from a dense wide-angle seismic profile

Orphan Basin is located offshore Newfoundland, East of Flemish Cap. The Basin is characterized by extented continental crust. It shows a zone of extreme extension that did not lead to formation of oceanic crust. The OBWAVE (Orphan Basin Wide-Angle Velocity Experiment) project has acquired refraction seismic data, along a pre-existing reflection line. The spacing of the ~100 instruments varies from 3 to 5 km along this 500-km-long line. The highest resolution part corresponds to the part of the profile where the crust was expected to be the thinnest. The final velocity model is developed using tomographic inversion of the refraction and wide-angle Moho reflection arrival times. This model shows clear basement highs, accommodating crustal thinning, and the variability of crustal thicknesses along the Basin (in particular where the crustal is less than 5 km thick). Furthermore, the upper crust and the lower crust seem to be decoupled. Thus, the high data density allows us to define crustal structures with greater detail than for typical studies and to improve the understanding of the processes leading to the extreme stretching of continental crust.