Mantle Exhumation and Post-Rift Magmatism at an Oblique Magma-Poor Continental Margin

Abstract

Continental breakup is a fundamental tectonic process, which leads to seafloor spreading and the generation of oceanic crust. However, the current understanding of continental margins, based largely on 2-D seismic transects, is inadequate to capture the spatial complexity of crustal evolution. Here we present a 3-D seismic velocity model through a young, magma-poor margin at the north-eastern Gulf of Aden. Our results highlight the 45° obliquity between the strike of crustal thinning and extension direction, which is accommodated by two transfer zones during the formation of the Continent-Ocean Transition (COT). This obliquity causes the margin to be segmented, which predates seafloor spreading. Along strike, we find a progressive eastward crustal thinning from 13 to 5 km, corresponding to a V-shaped COT. This eastward variation is characterized by (a) an eastward increase of mantle exhumation due to detachment faulting, and (b) post-rift magmatism emplaced onto serpentinized mantle in the west.