LATE PLEISTOCENE MARINE CHRONOLOGY OF THE GIPPSLAND LAKES REGION, AUSTRALIA

Abstract

Thermoluminescence dating is used to define the chronology of the coastal barriers of the Gippsland Lakes region, Australia. The area evidences a long history of marine deposition extending back to the Middle Pleistocene. However, the majority of Pleistocene barriers have formed since the Last Interglacial during two phases at 59 to 72 ka and 40 to 48 ka corresponding to interstadials. A third phase, with dates around the Last Glacial, appears to represent rapid shoreward movement of Late Pleistocene sediment from the shelf during the Holocene. Barriers have developed in an en echelon fashion seaward as the region has been uplifted tectonically. Some Late Pleistocene marine deposits reach elevations of 40 m above present sea level. These elevations imply rates of tectonic uplift exceeding 80 mm per thousand years, rates that may have increased toward the present. Deposits are preserved as isolated remnants because of subsequent fluvial and marine erosion. Both erosion and rebuilding may have occurred under the influence of tsunami originating from the south Tasman Sea. The unique distribution and preservation of recurrent interstadial barriers in the Gippsland Lakes region reflect rapid uplift, abundant sand supplies, and the proximity of this coast to sources for tsunami. [Key words: Gippsland Lakes, coastal barriers, chronology, thermoluminescence dating, Late Pleistocene, tsunami.]