Queensland plateau and Coral Sea Basin: structural and time-stratigraphic patterns

Abstract

The Western Coral Sea region contains one major and three minor marginal plateaux, partly surrounding a deep abyssal plain. The Coral Sea Abyssal Plain is underlain by about 1km sediment and oceanic crust generated by an early Eocene seafloor spreading phase. The large Queensland Plateau consists of subsided continental crust with basement rocks of Palaeozoic age which are tectonically part of the onshore Tasman Geosyncline. Graben, or continental rift features occur beneath the Queensland Trough, and beneath the plateau/basin margin. Here 1-3 kms of probable Upper Cretaceous "rift valley" sediments overlie basement. Subsidence of the plateaux followed seafloor spreading in the basin and marked the onset of "post-breakup" sedimentation. Lows in the plateau basement are infilled by Eocene sediments, while changing ocean current patterns gave rise to an Oligocene depositional break. Residual plateau highs along old Palaeozoic trends subsided in the early Miocene and are locally capped by modern coral reefs.