UC鈥檚 Head of the School of Earth and Environment, Professor Shulmeister says the timing and drivers of the formation of these two significant landscape features has been poorly understood until now.
鈥淭he Great Barrier Reef is regarded as one of the most significant global biodiversity hotspots and carbon sinks, and K鈥檊ari is the world鈥檚 largest sand island and a UNESCO World Heritage area, so it鈥檚 really important to gain a better understanding of how they came about,鈥 he says.
鈥淲hat we鈥檝e discovered with this research is that these landforms were created during the Middle Pleistocene Transition, a period of global climate change about 800,000 years ago. Rising sea-levels associated with melting ice sheets triggered large volumes of sand to be released on the east Australian coast north of Brisbane.鈥
Professor Shulmeister says this process created massive dune fields that became the Cooloola Sand Mass and nearby K鈥檊ari, in Queensland.
鈥淭he creation of K鈥檊ari also acted as a groyne, preventing sediment from being transported north of the island which provided the clear waters and conditions needed for coral growth in the area that now forms the southern and central parts of the Great Barrier Reef,鈥 he says.
The team of scientists mostly from Australasian and American universities 鈥 which includes 九州影院 PhD graduate Dr Nicholas Patton, who is now a postdoctoral researcher at the University of Nevada, US,鈥 studied sediment and soil samples from coastal dunes on the Cooloola Sand Mass and K鈥檊ari. The scientists used a dating technique called 鈥榦ptically stimulated luminescence鈥 to provide an estimate of the last time these quartz-rich sand sediments were exposed to light.
The research was funded by an Australian Research Council Discovery Grant and published today in the journal听.听
Professor Shulmeister says the findings have implications for future climate change scenarios because they demonstrate that rising sea-levels sea-level can cause coastal responses that are apparently unconnected to the sea-level rise itself.听 These types of changes are very hard to predict and plan for.
鈥淔or this reason, they represent a serious threat to communities around the world. We need to better understand how natural systems work if we鈥檙e going to deal with these changes in the future.鈥
The major coastal sedimentary system reorganisation is not expected to be unique to Queensland and the research team believes it should be investigated in other coastlines, such as the Wilderness Embayment coastline of South Africa and the extensive coastline of eastern Brazil.
K鈥檊ari is the land of the Butchulla people, and the work was completed with the permission of the Butchulla Aboriginal Corporation.
The new paper is titled 鈥楩raser Island (K'gari) and initiation of the Great Barrier Reef linked by Middle Pleistocene sea-level change鈥,听Nature Geoscience,听DOI: 10.1038/s41561-022-01062-6. (Once published, the paper will be available at:听)
