Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Ancient Mineral Shows Early Earth Climate Tough on Continents

A new analysis of ancient minerals called zircons suggests that a harsh climate may have scoured and possibly even destroyed the surface of the Earth's earliest continents.

Zircons, the oldest known materials on Earth, offer a window in time back as far as 4.4 billion years ago, when the planet was a mere 150 million years old. Because these crystals are exceptionally resistant to chemical changes, they have become the gold standard for determining the age of ancient rocks, says University of Wisconsin-Madison geologist John Valley.

Valley previously used these tiny mineral grains - smaller than a speck of sand - to show that rocky continents and liquid water formed on the Earth much earlier than previously thought, about 4.2 billion years ago.

In a new paper published online this week in the journal Earth and Planetary Science Letters, a team of scientists led by UW-Madison geologists Takayuki Ushikubo, Valley and Noriko Kita show that rocky continents and liquid water existed at least 4.3 billion years ago and were subjected to heavy weathering by an acrid climate.

Ushikubo, the first author on the new study, says that atmospheric weathering could provide an answer to a long-standing question in geology: why no rock samples have ever been found dating back to the first 500 million years after the Earth formed.

"Currently, no rocks remain from before about 4 billion years ago," he says. "Some people consider this as evidence for very high temperature conditions on the ancient Earth."

Previous explanations for the missing rocks have included destruction by barrages of meteorites and the possibility that the early Earth was a red-hot sea of magma in which rocks could not form.

The current analysis suggests a different scenario. Ushikubo and colleagues used a sophisticated new instrument called an ion microprobe to analyze isotope ratios of the element lithium in zircons from the Jack Hills in western Australia. By comparing these chemical fingerprints to lithium compositions in zircons from continental crust and primitive rocks similar to the Earth's mantle, they found evidence that the young planet already had the beginnings of continents, relatively cool temperatures and liquid water by the time the Australian zircons formed.

"At 4.3 billion years ago, the Earth already had habitable conditions," Ushikubo says.

The zircons' lithium signatures also hold signs of rock exposure on the Earth's surface and breakdown by weather and water, identified by low levels of a heavy lithium isotope. "Weathering can occur at the surface on continental crust or at the bottom of the ocean, but the [observed] lithium compositions can only be formed from continental crust," says Ushikubo.

The findings suggest that extensive weathering may have destroyed the Earth's earliest rocks, he says.

"Extensive weathering earlier than 4 billion years ago actually makes a lot of sense," says Valley. "People have suspected this, but there's never been any direct evidence."

Carbon dioxide in the atmosphere can combine with water to form carbonic acid, which falls as acid rain. The early Earth's atmosphere is believed to have contained extremely high levels of carbon dioxide - maybe 10,000 times as much as today.

"At [those levels], you would have had vicious acid rain and intense greenhouse [effects]. That is a condition that will dissolve rocks," Valley says. "If granites were on the surface of the Earth, they would have been destroyed almost immediately - geologically speaking - and the only remnants that we could recognize as ancient would be these zircons."

Additional information and images are available on the authors' web sites Zircons Are Forever ( and the Wisc-SIMS ion microprobe facility (

Other co-authors on the paper include Aaron Cavosie of the University of Puerto Rico, Simon Wilde of the Curtin University of Technology in Australia and Roberta Rudnick of the University of Maryland.

Jill Sakai | newswise
Further information:

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>