Prof. Patrick De Deckker will present recent work on Australian dusts.
This first part of my talk will provide an overview of the surficial geology of Australia with emphasis on regions from where dust can become deflated. This is important as previous studies ignored this aspect of the Australian regolith, and failed to distinguish areas with different geologies. This is particularly true of studies that examined the geochemistry of Australian dusts and links with potential deposition sites such as in Antarctica and comparison with South America.
The second part provides a review of the different geomorphological sites of dust deflation, with particular discussion on how dust particles can accumulate in regions linked to large playa lakes that are under the influence of groundwater below them. This is an important type of dust deflation, a process of which had insufficiently been detailed before. The processes involving evaporative pumping are explained and several illustrations are provided to document those processes and location of dust deposits. Another region of importance to dust deflation consists of extensive alluvial plains and these are also documented, with an area in the upper reaches of the Darling River being now documented more fully. Finally, the inter-dunal corridors in large dune fields are also mentioned as a source of dust as previous studies already show. This second section ends with the description of the two main Potential Source Areas (PSA) of dust in Australia and these are the Kati Thanda-Lake Eyre region of central Australia, and the Darling Riverine Plain in the upper reaches of the Darling River. These two regions are important for their geochemical fingerprints for transcontinental studies, and supported by satellite imagery that identify dust plumes originating from these regions.
The third section of the talk will examine the geochemical composition of Australian a PSAs by paying particular attention to Neodymium, Strontium and Lead isotopic ratios from both continents. We also suggest the possibility of comparing Nd and Pb isotopes as a way of fingerprinting geochemically between different Australian regions.