A research team from the University of Adelaide has discovered that the pink garnet grains found on the beaches of South Australia originate from the distant Antarctic region.
Yorke Peninsula and Fleurieu Peninsula in South Australia are home to several beaches with unusual pink sand. This pink hue comes from powdered garnet, but tracing the origin of garnet is not straightforward.
Beach in Dhilba Guuranda-Innes National Park, Yorke Peninsula turning pink due to garnet. (Photo: University of Adelaide)
The conditions required for garnet formation have not occurred frequently in Earth’s history. Therefore, uncovering where garnet comes from and how it reaches these beaches could provide valuable insights into geological history. In a recent study published in the journal Communications Earth and Environment, the team of scientists at the University of Adelaide found that the source of garnet is located thousands of kilometers away from the beaches of South Australia. IFL Science reported on June 13.
South Australia has two sources of garnet:
- The first source dates back 514 to 490 million years, during the formation of the Adelaide Fold Belt.
- The second source is much older, dating back 3.3 to 1.4 billion years during the formation of the Gawler Craton.
The University of Adelaide utilized laser technology to conduct a lutetium-hafnium dating method. This allowed them to demonstrate that some garnet grains on the beaches of South Australia originated from these two sources. However, most of the garnet found here is dated between 570 and 590 million years.
The research team discovered that the Cape Jervis Formation in South Australia contains garnet mixed with rock and other types of sand. As the rocks of the formation erode, garnet is released and can be transported to nearby beaches. The examination also revealed that this garnet is approximately 590 million years old.
Pink sand on the beaches of South Australia. (Photo: Stijn Glorie).
However, the geological activities in South Australia at that time could not have generated garnet on their own. So how did they end up in the Cape Jervis Formation?
According to the research team, they originated from Antarctica and were incorporated into Australia as part of the supercontinent Gondwana. “It can be imagined that millions of years of glacial movement eroded the underlying bedrock and transported these garnet grains northwest toward the edge of Antarctica – Australia,” explained Dr. Stijn Glorie from the University of Adelaide.
The research team believes that garnet formed during a period when the crust was thickening in eastern Antarctica, representing the initial stages of a large-scale mountain-building event. “It’s fascinating that we can trace the tiny grains of sand on the beaches of Australia back to an unexplored mountain range beneath the Antarctic ice,” shared Dr. Jacob Mulder, a member of the research team.
