The collision zone between the North d'Entrecasteaux Ridge and the New Hebrides island arc. 2. Structure from multichannel seismic data

Abstract

The d'Entrecasteaux zone (DEZ) collides with the central New Hebrides island arc and consists of two subparallel ridges that strike east-west, stand 1-2 km above the surrounding oceanic plate, and subduct obliquely (15°) northward beneath the arc. Rocks dredged from the north ridge as well as reflections evident in multichannel seismic reflection data indicate that this ridge has a volcanic origin. Seismic reflection data collected over the lower arc slope reveal that mass wasting deposits locally make up most of the accretionary wedge. Mass wasting is thought to occur as the accretionary wedge is uplifted in response to the northward oblique subduction of the north ridge. The toe of the north ridge flank marks an abrupt transition in the lithologies that make up the footwall of the interplate decollement. -from Authors