Published: Wed, May 10, 2017
Science | By Hubert Green

Scientists discover that Earth was one basically 'Waterworld,' without Kevin Costner

Scientists discover that Earth was one basically 'Waterworld,' without Kevin Costner

According to the research, small zircon mineral grains in rocks from Australia's Jack Hills and their composition tell the scientists about the magma - molten rock from within the Earth - from which the grains came, and thus about conditions on the planet during its early history. It was barren, smooth and nearly entirely under water with a few small islands, according to new research from the Australian National University.

The Jack Hills, in mid-west Western Australia, are home to the world's oldest known mineral samples, called detrital zircon grains. "Our study shows that during the first 700 million years of the Earth had mountains and collisions with continents, it was much calmer and boring place", says lead researcher Anthony Burnham from the Australian national University.

Earth itself is around more than 4.5 billion years old while the first form of any life emerged later, some 3.8 billion years ago. The first life on the planet is thought to have popped up over a billion years later, so for a very, very long time, our planet was probably a big wet ball with very little going on. The results clarify some ambiguity surrounding Earth's earliest history and help to understand how Earth's crust has changed over time.

Scientists from the Australian National University in Canberra studied the elements present in younger zircons, of known origin, to create a geological "Rosetta Stone" to determine how the Jack Hills' zircons formed.

"Sediment melting is characteristic of major continental collisions, such as the Himalayas, so it appears that such events did not occur during these early stages of Earth's history", he said.

The basin, located in Sudbury, was created 1.85 billion years ago when a meteorite slammed into our planet.

Along with the melted target rocks that first filled the area after the impact, the researchers also found distinctly shaped volcanic fragments that resemble a 'crab claw'.

"Scientists in the field were able to build on each other's work to gain a better understanding of early Earth".

Dr. Antony Burnham from the ANU Research School of Earth Sciences with a sample of zircon under the microscope.

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