Early Earth Likely Had Livable Continents

Nov 21, 2005
Earth from space

A surprising new study by an international team of researchers has concluded Earth's continents most likely were in place soon after the planet was formed, overturning a long-held theory that the early planet was either moon-like or dominated by oceans.

The team came to the conclusion following an analysis of a rare metal element known as hafnium in ancient minerals from the Jack Hills in Western Australia, thought to be among the oldest rocks on Earth. Hafnium is found in association with zircon crystals in the Jack Hills rocks, which date to almost 4.4 billion years ago.

"These results support the view that the continental crust had formed by 4.4-4.5 billion years ago and was rapidly recycled into the mantle," the researchers wrote in Science Express. Led by Professor Mark Harrison of the Australian National University, the team also included University of Colorado Assistant Professor Stephen Mojzsis and researchers from the University of California, Los Angeles and Ecole Normale Superieure University in France.

The researchers used hafnium as a "tracer" element, using isotopes to infer the existence of early continental formation on Earth dating to Hadeon Eon, which took place during the first 500 million years of Earth's history, said Mojzsis, an assistant professor of geological sciences at CU-Boulder. Mojzsis also is a member of CU-Boulder's Center for Astrobiology.

"The evidence indicates that there was substantial continental crust on Earth within its first 100 million years of existence," said Mojzsis. "It looks like the Earth started off with a bang."

A 2001 study led by Mojzsis published in the journal Nature showed evidence for the presence of water on Earth's surface roughly 4.3 billion years ago. "The view we are taking now is that Earth's crust, oceans and atmosphere were in place very early on, and that a habitable planet was established rapidly," said Mojzsis.

Copyright 2005 by Space Daily, Distributed United Press International

Explore further: Vitamin B3 might have been made in space, delivered to Earth by meteorites

add to favorites email to friend print save as pdf

Related Stories

Impacts could be boon for subterranean life

Apr 16, 2012

An incoming asteroid is trouble whether you're a dinosaur or a Bruce Willis fan. But microbes living deep underground may actually welcome the news, according to a recent study of an ancient impact in the ...

Recommended for you

Astronauts to reveal sobering data on asteroid impacts

13 hours ago

This Earth Day, Tuesday, April 22, three former NASA astronauts will present new evidence that our planet has experienced many more large-scale asteroid impacts over the past decade than previously thought… ...

Rosetta instrument commissioning continues

14 hours ago

We're now in week four of six dedicated to commissioning Rosetta's science instruments after the long hibernation period, with the majority now having completed at least a first initial switch on.

Astronaut salary

14 hours ago

Talk about a high-flying career! Being a government astronaut means you have the chance to go into space and take part in some neat projects—such as going on spacewalks, moving robotic arms and doing science ...

User comments : 0

More news stories

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Hubble image: A cross-section of the universe

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Chronic inflammation linked to 'high-grade' prostate cancer

Men who show signs of chronic inflammation in non-cancerous prostate tissue may have nearly twice the risk of actually having prostate cancer than those with no inflammation, according to results of a new study led by researchers ...