South Australia ’s Yorke and Fleurieu Peninsulas host some unusually bleached beaches . The pink color was already known to be pulverized garnet , but an attempt to observe the reservoir has expose a very unlikely location buried in ice and K of kilometers aside .

South Australia is known for pink things , including itsfamous lakesand the boxershorts of itsformer premier . Somewhat less well known are the pinkish sands on the peninsulas either side of the Gulf of St Vincent . On some beaches these pinkish grains are uncommon enough to be just noticeable , but others are predominantly pink .

Identifying the sand as being from garnet smashed against other rock’n’roll is relatively gentle , but detect the generator is voiceless . The conditions toproduce garnethave not occurred often in Earth ’s history . Scientists decided if they could work out where the garnet came from , ravel the route by which it reach these beach could learn us a lot about the geologic history of the surface area .

South Australia had two known informant of garnet . One occurred 514 - 490 million years ago when the Adelaide Fold Belt was take form nearby . The other was much earlier when the Gawler Craton , which now makes up the middle of the state , was built between 3.3 and 1.4 billion year ago .

The University of Adelaide has pioneer a method for using optical maser to perform lutetium - hafnium dating . Using this they were able to show that some garnet grain on the Department of State ’s beach come from each of these events . However , the most abundant garnet grains have an years of 570 - 590 million years .

“ The garnet is too youthful to have come from the Gawler Craton and too sure-enough to have come from the eroding Adelaide Fold Belt , ” said University of Adelaide PhD pupil Sharmaine Verhaert in astatement . “ Garnet need high temperatures to organise and is usually associated with the formation of large mountain whack , and this was a meter when the South Australian crust was relatively nerveless and non - mountainous . ”

Verhaert and Dr Stijn Glorie needed to look further afield , but knew prolonged time in marine environments demolish garnet so it probably would n’t be too far .

They realised that the Cape Jervis Formation , which overlaps with the Fleurieu Peninsula , contains garnet miscellaneous stone and othersands . When the rock music of the Formation gnaw at , the garnet escapes and can stop up on nearby beach . Moreover , examination revealed this garnet as 590 million years old , snug enough to what they were looking for .

This , however , only pushes the motion one step further up the chain . If South Australia was too inactive at the time to bring on its own garnet , how did it get into the Cape Jervis Formation , from which it has since gnaw ?

The answer , Verhaert , Glorie and carbon monoxide gas - generator conclude , is that it came from Antarctica when it was joined to Australia aspart of Gondwana . For obvious reasons we do n’t know a lot about Antarctica ’s rock-and-roll , but garnet of the veracious long time has been get hold in an outcrop of theTransantarctic Mountainsthat divide East and West Antarctica . It ’s likely there is a draw more buried under the methamphetamine where we ca n’t reach it .

“ It is conceivable that millions of days of ice rink transport eroded the bedrock underneath and transport this cargo of garnet north - west , towards the conjugate solution Antarctic - Australian gross profit , ” said Glorie .

The authors opine the garnet was formed during a stop of crustal inspissation in east Antarctica that represented the first stagecoach of a major mountain - construction result .

The garnet was arriving in South Australia around the same time its hill were recording the opinion of some of theearliest complex life var. , whose epoch is list aftera location there .

From there , the garnet deposits would have been stored in glacial sediments for hundreds of millions of twelvemonth until erosion allowed them to escape , to be wash up on nearby beach .

“ We have efficaciously uncovered a major good deal edifice consequence that redefines the timing of the onset of convergence in the Pacific Ocean , ” Glorie state .

The work is published undefendable access inCommunications Earth and Environment .