Led by Priyadarshi Choudhury, a research fellow in the Monash School of Earth, Atmosphere and Environment, the study integrated the igneous and sedimentary history of the Archaean Craton to demonstrate that stable continental landmass rose from sea level between 3.3 and 3.2 billion years ago. were beginning to emerge above – that’s 700 million years earlier than most models predicted.
Chowdhary, who is an alumnus of Jadavpur University, Kolkata, told TOI: “…we didn’t have continents from the beginning of Earth and only oceans. At some point continents started to form and eventually rise over oceans. Initially The time was thought to be 2.5 billion years ago today. Now, we have solid evidence that an ancient continent, which we studied from Odisha and Jharkhand in India (Singhbhum Craton), erupted from the oceans 3.2 billion years ago. Similarly, the continents in Australia and South Africa arrived 3 billion years ago.”
In addition to Chowdhury, the research was carried out by seven others, including three more people of Indian origin: Subhajit Roy, Jacob A. Mulder, Peter A. Cawood and Oliver Nebel of Monash University; Shubham Mukherjee from Delhi University; Surjendu Bhattacharjee from the California Institute of Technology and Ashley Ann Wainwright from the University of Melbourne. Conclusions have been published by Proceedings of the National Academy of Science (PNAS).
The researchers said their study is important because it is important to understand when and how the subaerial continental crust first formed, as it played a key role in establishing Earth’s habitability.
Their study, they say, pushes back in time and proposes a fundamentally different mechanism for the earliest continental submersion (out of the oceans).
“We have sporadic evidence of land formation early in Earth’s history, but this is the first time we’ve found evidence of an entire continent rising above sea level so quickly. The first continental landmass was important for the spread of early life, “They said.
These landmasses created the shallow marine habitats necessary for photosynthetic communities and provided a continuous supply of bio-essential nutrients through continental weathering and erosion.
Researchers say the weathering of continental landmass also prompted dramatic changes in Earth’s early atmosphere, oceans and climate. “These changes were crucial to the development of some of the world’s most important metal ore deposits,” said study co-author Jacob Mulder. For example, Earth’s largest iron ore deposits form in the shallow seas surrounding the newly emerging continental crust.
On modern Earth, the formation of highly permanent continental topography is driven primarily by the subduction and collision of tectonic plates. However, researchers have shown that the rise of the continents 3.2 billion years ago was unlikely to be due to this.
Having modeled the magmatic history of the Singhbhum Craton, they suggest that the immersion was driven by the displacement of giant granite bodies over a period of 200–300 million years, which led to a buoyant formation of silica-rich crust rising above the surrounding ocean. Inflated the plateau.
“These findings challenge the current view linking subaerial landmass to plate tectonics on the early Earth,” said study co-author Professor Cawood, adding that their study contributes to a better understanding of the timing and processes of which The Archean continental crust is formed and interacted by Comprehensive Earth System.
They conclude that the findings are important for developing next-generation models to understand the formation and location of metal ore deposits.”
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