3D Seismic Reflection Experiment: Magma starved rifting at the Galicia Deep Basin

In Summer 2013, a 3D reflection and a long offset seismic experiment were conducted at the Galicia rifted margin by investigators from the US, UK, Germany, and Spain. The 3D multichannel experiment covered 68 km by 20 km (1360 km2), using the RV Marcus Langseth. Four 6 km long streamers were deployed at 12.5 m hydrophone channel spacing. The streamers were 200 m apart. Two airgun arrays, each 3300 cu in, were fired alternately every 37.5 m, to collectively yield a 400 m wide sail line consisting of 8 CMP lines at 50 m spacing. We have focused on the rifted margin in the Atlantic Ocean offshore Iberia, known as the Deep Galicia Basin. It encompasses the late stage rifting and the first exhumation of serpentine/peridotite. Several unusual features are, 1) the S-reflector forms a detached, low-angle, normal fault that forms a structural crust and a transitional Moho, 2) a Peridotite Ridge that seems to bound continental crust to the east and may have formed serpentine diapiric features, and 3) dramatic normal faulted blocks that have been faulted, rotated, and then re-faulted, perhaps multiple times.