Insights into the Australian desert dunefields from a database of luminescence ages

The database of luminescence ages of Australian deser t sand dunes (all non-coastal, non-lunette dunes) is investigated for insights into the development of dunefields and aridity in the late Quaternary. The database includes 582 individual age determinations (at the time of writing) covering much of the Australian continent (18-43 degrees S latitude). The oldest luminescence age determination made is 380 ka, although older estimates from cosmogenic burial ages have been made. Many dunes record multiple episodes of growth, preserving several units of sand sometimes separated by palaeosols. In addition, the surface form of most Australian dunes shows little evidence of substantial post-formation alteration. This conservative behaviour makes Australian longitudinal dunes excellent (if episodic) recorders of past aeolian activity and environments. The full compilation of ages has been used in several ways to deduce a 'continent-wide' picture (usually on the assumption that climatic changes are or should be synchronous at that scale). Here frequency distribution of age determinations is compared with analysis of the distribution and range of sedimentation rates. Some findings (increase in activity around 40 ka; LGM peak) are consistent across these different approaches but some features are quite different. One of the sources of uncer tainty in all approaches is the treatment of errors which grow with sample age (while time windows are usually held constant). An apparent late Holocene peak in dune activity may purely be a product of the time window considered.1 page(s