Detachment faulting at ocean core complexes

Abstract

Intracrustal reflections from a Cretaceous inside corner are interpreted as a detachment fault that dips gently within the basement and can be followed up the flank of a domed high. The fault heave is sufficient for ridge-normal extension to have exhumed deep-crustal and probably mantle rocks, as sampled at some inside corner domed massifs. The morphology of these massifs closely resembles that of the Cretaceous high, implying that the structures are analogous and supporting the notion that modern inside corner massifs are oceanic core complexes formed by unroofing the footwalls of similar detachment faults, partially exposed as corrugated slip surfaces. This is the first demonstration of the overall geometry of an oceanic core complex detachment fault.