A cretaceous (Turonian) core from the Naturaliste Plateau southeast indian ocean

Abstract

An Upper Cretaceous (Turonian) sediment core was recovered from the northeastern s slope of the Naturaliste Plateau, eastern Indian Ocean. At the core site, coarse grained foraminiferal sand of Recent-Pleistocene age disconformably overlies a white Cretaceous chalk consisting largely of planktonic organisms. The pelagic nature of the sediment suggests that the water depth at this core site was approximately the same in both Cretaceous and Pleistocene time. Bottom photographs and seismic profile records were also taken across this feature. The seismic profile records show a rather thin sediment layer with some thicker sedimentary pockets, possibly due to faulting. The south side of the Plateau is marked by a steep scarp with a well developed sediment “ramp” at its base. This sediment “ramp” probably owes its origin to longshore currents which sweep around the southwest tip of Australia. The Naturaliste Plateau is similar to other plateaus marginal to continents in that: (a) they have more or less flat summits, (b) Pleistocene overburden is thin or lacking, and (c) steep scarps are present on at least one side.