CENOZOIC BIOGENIC MOUNDS AND BURIED MIOCENE(QUESTIONABLE) BARRIER-REEF ON A PREDOMINANTLY COOL-WATER CARBONATE CONTINENTAL-MARGIN EUCLA BASIN, WESTERN GREAT-AUSTRALIAN-BIGHT

The southern continental margin of Australia is the largest area of co ol-water carbonate shelf deposition on the globe. Interpretation of 54 95 km of airgun seismic-reflection data in the western part of the Gre at Australian Eight indicates that the 700-m-thick Cenozoic section of the offshore Eucla basin was deposited largely as a prograding cool-w ater, middle- to high-latitude carbonate ramp, characterized by widesp read development of broad, low-relief, biogenic (bryozoan[?]-sponge), shelf and upper-slope mounds. The succession also contains a spectacul ar and extensive (>475 km long) buried middle Miocene barrier reef (th e Miocene Little Barrier Reef) parallel to the modern shelf edge. This rimmed carbonate platform margin represents an episode of warm-water sedimentation during a global climatic optimum, probably coupled with strong eastward flow of a proto-Leeuwin Current. The late Miocene eust atic sea-level fall produced an areally restricted debris-apron sequen ce at the foot of the reef escarpment. The carbonate platform is cappe d by a Neogene cool-water carbonate ramp succession typified by aggrad ational to sigmoidal sequences, punctuated by periods of cold(?)-water , sea-floor erosion. Interpretation of this succession in the light of global and local tectonic and oceanographic events illustrates the do minant influence of water temperature on carbonate platform and reef g rowth throughout the Cenozoic.