Researchers believe K'gari shaped reef

Researchers have identified when Fraser Island (K'gari) formed and how its enormous land mass shaped the southern and central Great Barrier Reef.

A peer-reviewed study unearthed that K'gari formed between 0.7 and 1.2 million years ago and the island dramatically reduced sediment supply to the continental shelf to it's north.

Scientists from University of Queensland in their Nature Geoscience article found K'gari facilitated widespread coral reef formation in the southern and central Great Barrier Reef and was a necessary precondition for its development.

Once K'gari and it's dunes were emplaced, they acted as a barrier to longshore drift which redirected sediment off the edge of the continental shelf, resulting in an increase in carbonate sedimentation and reef growth north of the island.

But before it existed, northward longshore drift would have interfered with coral reef development in the southern and central GBR, which an Ocean Drilling Program referenced in the paper supports.

Scientists targeted basal units, sediment and soil sequences along Rainbow Beach and Cooloola Sand Mass cliffs in their study.

Their research indicates the largest and most extensive dune packages formed during "post-glacial sea-level transgressions."

They say the island prevented northward terrestrial sand transport which led to a decrease in sediment across the southern GBR.

From this, carbonate sedimentation dominated and was vital to the development of the reef.

Whether longshore sediment transport also contributed to reef development further north requires more research, they said.

The joint study from the University of Queensland, University of Canterbury, The Australian National University, Flinders University, University of Western Australia, Stockholm University can be found in Nature Geoscience.