TAPHONOMIC COMPARISON OF MODERN AND PLEISTOCENE CORAL ASSEMBLAGES: THE HOUTMAN-ABROLHOS ISLANDS, WESTERN AUSTRALIA

Taphonomic analyses of reef corals have been conducted in multiple reefal environments present in a great many locations including the Great Barrier Reef, Florida Keys, Bahamas, and Papua New Guinea. However, taphonomic research on modern and Pleistocene reefs of Western Australia has not been published. The study presented here examines taphonomic signatures retained by modern and Pleistocene corals in order to determine taphofacies and aid paleoenvironmental reconstruction of the coral fossil assemblages exposed along the Western Australian coast. The taphonomic condition of specimens composing modern and Pleistocene coral assemblages sampled from similar environmental regimes in the Wallabi Group of the Houtman-Abrolhos Islands, Western Australia was compared between times (modern vs. Pleistocene) and coral growth forms (plate vs. branching). Semi-quantitative analyses of dissolution, abrasion and encrustation, as well as quantitative analyses of bioerosion were performed. Results show a significant difference between the preservation style of fossil and modern coral assemblages, which may indicate environmental variation between them. Within the Pleistocene assemblage, branching coral colony growth forms have a higher degree of encrustation while plate corals show more dissolution and abrasion. The modern reef death assemblage does not show marked differences in condition between coral growth forms. These results contrast with those obtained for the same colony growth forms in Papua New Guinea and the Great Barrier Reef, suggesting that similar reef subenvironments may have variable preservation potential.