Marginal plateaus: Their relationship to continental shelf sedimentary basins in Southern Australia

Abstract

Two marginal plateau areas, the Ceduna and the Beachport, occur beyond the continental shelf off southern Australia. These appear superficially similar to the well‐documented Blake Plateau, off Florida. In the Australian case the plateaus almost certainly represent extensions of the Australian continental shelf zone. They are most likely composed largely of Mesozoic sediments overlain by Cainozoic shelf and slope facies. The Beachport Plateau may be a block which was down‐faulted from the shelf in pre‐Cainozoic times. In both cases the plateaus have acted as localised sediment traps. They have prevented the prograding shelf sediments of the Tertiary from slumping downslope to build up notable abyssal fans at the base of the continental slope.