d'Entrecasteaux Zone, trench and western chain of the central New Hebrides island arc: Their significance and tectonic relationship

Abstract

The absence of a trench and the existence of a separate, western chain of islands in the central New Hebrides island arc are a consequence of earlier tectonic evolution, and not the result of subduction of the d'Entrecusteaux Zone as was previously suggested. Because of tectonic consolidation in the western islands prior to present subduction, a resistant block was created opposing subduction, and a trench nevcr did form here. The d'Entrecasteaux Zone is responsible only locally for additional deformation of the subducting plate, in a way that can be regarded as an initial stage of obduction.

Effects of trench‐perpendicular ridge subduction on accretionary wedge deformation: Clues from analogue modelling

“…The North d'Entrecasteaux Ridge, an east-west-trending aseismic ridge with a height of 2-4 km and width of 40 km, is subducting beneath the New Hebrides Trench with an average convergence rate of 10 cm/year in the direction of N76°E, nearly perpendicularly to the trench (Collot, Greene, Fisher, & Geist, 1994;Fisher, Collot, & Geist, 1991). Latest Palaeocene to early Oligocene mid-oceanic ridge basalt (MORB) were dredged from the North d'Entrecasteaux Ridge (Maillet, Monzier, Selo, & Storzer, 1983), which may have been subducted since about 2 Ma (Collot, Daniel, & Burne, 1985;Daniel & Katz, 1981). A seismic line 104 passes through the unsubducted part of the ridge as well as the accretionary wedge that is situated on top of the subducting ridge ( Figure 13).…”

Probabilistic Seismic Hazard Model for Vanuatu

“…Wallace et al (2005) demonstrated that active rifting in the North Fiji basin is probably related to these collisions as well. Another important factor influencing the deformation of the plate contact zone is the presence of rigid, old (Miocene) crustal blocks in the forearc (Daniel and Katz, 1981;Collot et al, 1985).…”

Introduction

“…3). The formation of these basins in the Central Basin region is influenced by the collision of the DEZ with the central New Hebrides Island Arc opposite Espiritu Santo and Malakula islands (Karig and Mammerickx, 1972;Daniel and Katz, 1981;Burne et al, 1988;Collot et al, 1985). Since the Pliocene, this collision has been characterized by wrench-fault tectonics, that is, crustal extension and transtension creating horst-and-graben blocks, and crustal compression and transpression uplifting and shifting those same structures .…”