July 13 () –
Researchers at Curtin University have established a new framework for dating Earth’s evolution, including continent formations and mineral deposits.
The investigation, published in Earth Science Reviews, studied Australia’s abundant lead and zinc ore deposits along with a vast global database and determined that 3.2 billion years ago was a critical point in Earth’s history when the Earth changed from a layer cake structure to a a remix mode possibly driven by the beginning of plate tectonics on a global scale, a process that still dominates the Earth system today.
Principal investigator Dr. Luc Doucet, from Curtin’s Earth Dynamics Research Group, said one of the main questions they aimed to answer was When did the continents as we know them today first form?
“To answer this question, we had to determine when the composition of the continental crust started to differ significantly from that of the Earth’s mantle from which the continental material was extracted,” said Dr Doucet. it’s a statement.
“The challenge was that we first needed to understand how Earth’s mantle evolved since the Giant Moon formation impact 4.5 billion years ago, when a giant asteroid collided with proto-Earth and modified the Earth’s core and mantle. Land. We need to reconcile this well-established theory with the current mantle composition.
“We use lead isotope compositions of rock samples across space and time, including primitive meteorites that formed at the same time as the solar system and various components of Earth’s layers, to reconstruct the evolution of the Earth’s mantle”.
Co-author Dr Denis Fougerouse, from Curtin’s School of Earth and Planetary Sciences, said they could now compare the evolution of Earth’s mantle with that of the continent by using measurements of large deposits of lead and zinc. , known to track the composition of the continental crust over time and Australia is endowed with an abundance of such deposits.
“Australia has an estimated 52 billion tonnes of lead-zinc ore, making it the world’s second largest reserves, behind only China. They range from 3.4 billion years old in the Pilbara region of Western Australia to relatively young deposits of 285 million years, making them perfect for our studiosaid Dr. Fougerouse.
Co-author Dr. Hugo Olierook, from Curtin’s John de Laeter Center, added that the team’s analysis revealed that the lead and zinc deposits began to exhibit significant differences from Earth’s mantle. about 3.2 billion years ago.
“This period is considered to be the point at which plate tectonics began to be the dominant driver of continent formation on Earth. Earth is the only planet in our solar system to have plate tectonics, and perhaps not by coincidence, the only planet capable of supporting lifesaid Dr. Olierook.
A by-product of this groundbreaking research is that the researchers will need to calibrate the radiometric ages they acquired to date Earth evolution and mineralization events in the future using the uranium-lead isotope system curves recently established by the Curtin group.
