Exmouth Plateau revisited: scientific drilling and geological framework

Abstract

The Exmouth Plateau is a very large marginal plateau containing 10km of Phanerozoic sediments and is underlain by continental crust that was stretched and thinned, probably in the Late Permian. For much of the Mesozoic it was part of the northern shore of eastern Gondwana and the southern shore of Tethys, and a large part of the Phanerozoic sequence consists of Triassic fluviodeltaic sediments. Late Triassic to Late Jurassic rifting caused block-faulting, and several large grabens have a thick fill of Jurassic shallow-marine carbonates and coal-measure sequences. In 1988, the Ocean Drilling Program drilled at six sites on the plateau during Leg 122 and two sites on the adjacent abyssal plains during Leg 123, designed to address the geological history of this continental margin, as an exemplar for other, more heavily sedimented margins. The six Exmouth Plateau holes cored a total of 3370m of Upper Triassic, Cretaceous, and Cenozoic strata, with excellent recovery in all but Upper Triassic carbonates. This paper introduces the results contained in 55 papers included in this volume, covering most aspects of passive margin evolution and palaeoenvironment, biostratigraphy, magnetostratigraphy, chemostratigraphy, sequence stratigraphy, rift rectonics, eustatic sea-level fluctuations, cyclic sedimentation, and orbital forcing. This paper also outlines the paleogeographic development of the region from Late Triassic to Albian times. -from Authors