CUVIER BASIN - PRODUCT OF OCEAN CRUST FORMATION BY EARLY CRETACEOUS RIFTING OFF WESTERN AUSTRALIA

Four high-quality seismic refraction profiles were recorded parallel to the structural grain in the Cuvier Basin and adjacent Wharton Basin to study the nature of the earth's crust in this area. The principal result of this experiment is that this area is generally floored with oceanic crust. No transitional velocity structure exists at the base of the continental slope. Departures from a standard oceanic crustal section are observed on an intermediate profile that are attributed to structural complications on the flank of an abandoned spreading ridge. Additional magnetic anomaly profiles in the eastern Cuvier Basin are used to correlate the lineations in that area with Early Cretaceous reversals M-5 to M-10. This correlation dates the onset of plate separation at 120-125 m.y., essentially contemporaneous with the opening of the Perth Basin to the south. However, it leaves a 220-km gap between M-4 and M-5 in the Cuvier Basin that suggests a ridge jump of that magnitude occurred nominally at 118 m.y. Early Cretaceous magnetic lineations northwest of the Exmouth Plateau suggest that spreading at the seaward edge of the Exmouth Plateau began 120 m.y. ago, while Late Jurassic marine sediments and fault structures landward of the Exmouth Plateau suggest rifting in that area at 155 m.y. © 1979.