Research from Western Australian scientists has shed new light on how the Earth’s first continental crust was formed.
The team of scientists, which included Dr Laure Martin and Mr Matvei Aleshin from The University of Western Australia and was led by the Geological Survey of Western Australia and Curtin University, measured compositions of oxygen in ancient granites in the Pilbara using the ion microprobe Cameca IMS1280 at UWA.
The scientists found that the water required to produce the granites did not come from above but was supplied from the mantle, which is the thick layer below the Earth’s crust.
Dr Laure Martin from the UWA Centre for Microscopy, Characterisation and Analysis (CMCA) said the ion microprobe hosted at CMCA was unique in Australia.
“It is the only instrument with the capability of resolving the complexity of such old samples,” Dr Martin said.
“Using the ion microprobe, we were able to measure oxygen isotopes in tiny mineral, time capsules called zircon and we found that the water, which allowed for the formation of the first granites, had a similar signature to that of the mantle.”
Dr Hugh Smithies from Geological Survey of Western Australia said continents were made of granite that first began to appear around the planet almost four billion years ago.
“Here in Western Australia, we have some of the oldest granites known, making our own backyard the ideal place to find out more about how the early Earth worked,” he said.
“Water entering the Earth’s deepest crust is believed to be the key to producing these granites.”
Co-funded by the State Government’s Exploration Incentive Scheme (EIS), the research supports GSWA’s aim to better understand the geological evolution of Western Australia and provide comprehensive geoscience data for all land use activities.
The ion microprobe Cameca IMS1280 was funded through the National Collaborative Research Infrastructure Strategy program by Microscopy Australia and AuScope with support from UWA, State and Federal governments.
The research was published in the journal Nature.