Middle Miocene tropical oligotrophic lagoon deposit sheds light on the origin of the Western Australian coral reef province

The Western Australian margin is a unique coral reef province, with modern development occurring at latitudes as far south 29°S. genesis of this province may go back to the Oligo-Miocene, since geological features ~30 million-year-old and younger interpreted reefs are known from offshore seismic surveys. nature these is, however, uncertain, they only sparsely sampled, time-equivalent outcrops present in few remote understudied locations. This study investigates middle Miocene shallow-water limestones tropical fauna formed along North West Shelf (NWS) between ~13 Ma ~15 Ma, when southward extension was its maximum. cores investigated dominantly composed peloidal packstones micritic floatstones containing larger benthic foraminifera, Halimeda sp. scleractinian corals, including reef-building genera, that accumulated protected oligotrophic, warm-water lagoonal environment. Climate therefore warm during acme development, despite NWS being located ~7° further than position time. Results investigation also support existence strong flowing Leeuwin-current-style oceanic circulation Miocene, which could have transported south-east Asia margin. Development lagoon been promoted by aridification coast bordering NWS, repeated eustatic-driven exposures NWS.