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: Chilly end for sex geckos sent into space by Russia

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

We are all made of stars

1 hour ago

Astronomers spend most of their time contemplating the universe, quite comfortable in the knowledge that we are just a speck among billions of planets, stars and galaxies. But last week, the Australian astronomical ...

ESA video: The ATV-5 Georges Lemaitre loading process

1 hour ago

This time-lapse video shows the ATV-5 Georges Lemaitre loading process and its integration on the Ariane 5 launcher before its transfer and launch to the International Space Station from Europe's Spaceport in Kourou, French ...

Raven soars through first light and second run

3 hours ago

Raven, a Multi-Object Adaptive Optics (MOAO) science demonstrator, successfully saw first light at the Subaru Telescope on the nights of May 13 and 14, 2014 and completed its second run during the nights ...

Titan's subsurface reservoirs modify methane rainfall

3 hours ago

(Phys.org) —The international Cassini mission has revealed hundreds of lakes and seas spread across the icy surface of Saturn's moon Titan, mostly in its polar regions. These lakes are filled not with water ...

User comments : 0