The Distribution and Impact of Carbonate Sands on Southern Australian Beach-Dune Systems

The southern and southwestern Australian coast is the largest temperate carbonate province in the world, extending for over 6000 km. The carbonates are derived from two major sources. On the more exposed open coast shelf carbonates are produced at depths to 130 m and are swept landward by both the sea level transgression and the energetic wave climate to supply extensive beach and dune systems, with average volumes of 10000 m³ m^–1. In the more protected gulfs and bays, extensive seagrass meadows and their epi-fauna supply shell detritus to build wide sand flats and backing beach ridge systems. In addition, lithification of barrier deposits during glacial low sea level periods has produced thousands of kilometers of beach and dune calcarenite, which may be exposed as calcarenite sea cliffs up to 150 m high, and as islands and reefs. These deposits not only lock up carbonate sediments but have a major impact on wave shoaling and induce a calcarenite-controlled realignment of the modern shoreline and redistribution of wave energy, which in turn controls Holocene coastal evolution.