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Sydney breakthrough on formation of continents with UC San Diego

9 September 2016
International collaboration provides evidence for date of India-Eurasia collision

Researchers from universities in Sydney and California join forces to map the formation of the land mass we know as Asia.

A research team from the University of Sydney and the University of San Diego may have settled a long-running dispute over the date of the tectonic upheaval that led to the formation of the Asian continent.

The modern map of Asia began to take shape when the tectonic plate of India, moving at 15 centimetres per year, rammed into the Eurasian land mass millions of years ago. The collision unleashed shockwaves that led to the formation of the Himalayas and sent ripples along the seafloor to the south.

Newly published research by Professor Dietmar Mueller and Dr Kara Matthews from the School of Geosciences, with Professor David Sandwell from the Scripps Institution of Oceanography in California, provides the strongest evidence to date about when the collision occurred, suggesting that it took place about 47 million years ago.

Their research makes use of detailed maps of the ocean floor compiled from satellite data about the Earth’s gravity field.

The key to the breakthrough was the discovery in the Indian Ocean, east of Madagascar, of an oceanic microplate – a small piece of ocean crust the size of Tasmania – which was almost certainly dislodged by the shockwaves following the collision. The date when that occurred can be worked out from geomagnetic data.

“The ocean floor acts like a tape recorder as it records the successive reversals of the Earth’s magnetic field during seafloor spreading,” said Professor Mueller.

He added: “The timing of the India-Eurasia collision has been a major and long-standing controversy in plate tectonics and our research has produced the most precise date for the collision so far available.”

The University of Sydney and the Scripps Institution are both members of the EarthByte Group, an international partnership of universities, research centres and industry groups, which has developed the GPlates open-source plate reconstruction software.

Professor Mueller, Professor Sandwell and Dr Matthews – who is now at the University of Oxford – are also collaborating on a book chapter looking at the origins of seafloor tectonic fabric and new microplate discoveries in the Pacific Ocean.