The first research paper associated with the Australian Nuclear Science and Technology Organisation (ANSTO) and the University of Wollongong’s in situ carbon-14 extraction laboratory has provided evidence that the journey time of sediment originating in the Great Dividing Range on an interrupted downward to the mouth of the Murray exceeds one million years.
The Organisation said the paper had implications for interpreting the evolutionary history of landscapes in Australia and elsewhere.
“The extraction laboratory is one of only a handful in the world capable of measuring in situ carbon-14 and can be used as a new tool to better understand recent changes in Earth’s climate system and rates of landscape change over the past 20,000 years,” ANSTO said.
“Analyses of in-situ produced cosmogenic carbon-14, aluminium-26 and beryllium-10 using ANSTO’s accelerators, quantified the evolution of sedimentary movement as a conveyor belt from the source in the mountains to the sink at the ocean,” it said.
Research Scientist at ANSTO, Reka Fulop said there shouldn’t have been any carbon-14 remaining in the sediment if transport was a single event, as it should have decayed away, given the relatively short half-life of the isotope.
“But there was, which suggested that the sediment was moving, stopping, mixing with other sediment and then moving again in multiple events of burial and re-exposure,” Dr Fulop said.
“In some studies there is an assumption that the environmental signal is transmitted directly from the source to the sink and any variability in the origin of the sediment is linked to changes in sediment production or discharge rates,” she said.
Dr Fulop said the research suggested this was not the case when sedimentary movement was occurring on a large scale in a tectonically quiescent, arid landscape, such as the Murray Darling Rivers Basin.
