Monday 20 February 2017

TCD geologists link ancient crystals with cosmic blast

Published 29/04/2016 | 02:30

Trinity College Dublin
Trinity College Dublin

A team from Trinity College has unearthed ground-breaking research that suggests Earth shares more similarities with our neighbours in the solar system than previously believed.

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A study of the oldest pieces of rock on Earth supports the team's view that our planet was regularly pummelled by asteroids billions of years ago. These asteroids left giant craters on the moon and elsewhere in the solar system, including planet Mercury.

The study of microscopic rocks called zircon crystals by a team of researchers at the School of Natural Sciences at Trinity College found that the prehistoric crystals were probably formed after fiery meteorites crashed violently into the Earth more than four billion years ago.

The collisions caused the Earth's crust to melt and form giant pools of molten rock that left massive "impact" craters around the world. They include the world's second largest and best preserved 200km wide crater known as the Sudbury Basin in Ontario, Canada.

But what the team recently discovered at the two-billion-year-old basin is thought to be truly ground-breaking.

It was previously thought the Earth's oldest zircon crystals, which measure around the width of a human hair, were formed due to the shifting of tectonic plates - giant slabs of rock which form the outer crust of the Earth's surface.

But after studying thousands of crystals taken from the basin in 2014 and comparing them with zircon crystals found in Australia believed to be more than four billion years old, the team discovered the Sudbury crystal compositions "were indistinguishable from the ancient set".

Lead researcher Gavin Kenny, whose findings have been published in the academic journal 'Geology', said the team believed "our planet suffered far more frequent bombardment from asteroids early on than it has in relatively recent times."

This suggests Earth shares striking similarities with other planets. "It makes more sense that the Earth looked like Mercury and that we share more of a similarity with other planets," Mr Kenny said.

Irish Independent

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