COLONIZATION AND REEF GROWTH ON A LATE PLEISTOCENE ROCKY SHORE AND ABRASION PLATFORM IN WESTERN-AUSTRALIA

A low, rocky shoreline and attached abrasion platform of Late Pleistoc ene age are marked by a sharp disconformity within the Tamala Limeston e Formation, exposed at Cape Burney facing the Indian Ocean near Geral dton, Western Australia. Colonization by an intertidal to shallow subt idal biota dominated by encrusting coralline red algae, oysters, and t ube-dwelling worms occurs on a sandstone surface with a channeled topo graphic relief of 20-30 cm. The encrusting cup coral Rhizoaochus tuber culatus also is present, and this report details what is probably the first fossil occurrence of that species. The ancient rocky shore above this level retains trace fossils characteristic of a boring barnacle, probably belonging to Lithotrya. Herein named the Cape Burney sandsto ne, the distinctive unit on which the disconformity sits is assigned m ember status within the Tamala Limestone. Shell beds with a diversity of 35 species, dominated in volume by robust gastropods such as Turbo intercostalis and T. torquatus, thinly drape portions of the disconfor mity surface. Succeeding the shell drapes is a reeflimestone with a ma ximum thickness of more than 2 m. The limestone is a massive accumulat ion of collapsed but otherwise mostly undisturbed coral fronds belongi ng primarily to a robust species of Acropora. Herein named the Bootena ll limestone, this unit is assigned member status within the Tamala Li mestone. Based on an analysis of electron spin resonance (ESR) from Ac ropora samples, the fringing reef developed between 120 ka and 132 ka, in the terminal stage of coastal transgression during the last interg lacial period (Oxygen Isotope Substage 5e).