Evolution of Holocene coastal environments near Robe, southeastern South Australia

• Published in: Quaternary international 1999-01, Vol.56 (1), p.81-97
• Main Authors: Cann, J.H., Murray-Wallace, C.V., Belperio, A.P., Brenchley, A.J.
• Format: Article
• Language: English
• ISSN: 1040-6182; 1873-4553
• DOI: 10.1016/S1040-6182(98)00023-8

Coastal Robe Range, and adjacent Woakwine Range, situated 10–15 km inland, are the most southwesterly and youngest of a series of parallel, low altitude, Pleistocene beach-dune barriers in southeastern South Australia. In the early Holocene, the post-glacial marine transgression flooded the Robe–Woakwine Corridor, thus forming a shallow back-barrier lagoon, open to the Southern Ocean near the present towns of Robe and Beachport. Marine to lagoonal, bioclastic, carbonate-quartz sedimentation prevailed within the corridor from ca. 7500–2000 yr BP. Along the seaward side of Robe Range, transgressive sands were deposited initially as ephemeral sand flats, but were mostly redistributed as coastal dunes, which today remain active and blanket the Pleistocene core of the range. Sand was also transported along the coast and deposited within the protected embayments of Guichen and Rivoli Bays, in the form of prograded beach ridge plains, eventually isolating the back-barrier lagoon from the open ocean. Sediment aggradation within the lagoon, cessation of marine influence and regional uplift of 0.7 m during the Holocene, combined to transform the corridor to a lacustrine landscape. Fossil molluscs, foraminifera and ostracods are diagnostic of successive palaeo-environments, and thus signify stages in the rapid geomorphic evolution of the coastal Robe–Woakwine Corridor.