Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Oldest known rocks discovered

26.09.2008
Canadian bedrock more than four billion years old may be the oldest known section of the Earth's early crust. Scientists at the Carnegie Institution used geochemical methods to obtain an age of 4.28 billion years for samples of the rock, making it 250 million years more ancient than any previously discovered rocks. The findings, which offer scientists clues to the earliest stages of our planet's evolution, are published in the September 26 issue of Science.*

The Nuvvuagittuq greenstone belt is an expanse of bedrock exposed on the eastern shore of Hudson Bay in northern Quebec and was first recognized in 2001 as a potential site of very old rocks. Samples of the Nuvvuagittuq rocks were collected by geologists from McGill University in Montreal and analyzed by Jonathan O'Neil, a PhD student at McGill, and Richard Carlson at the Carnegie Institution's Department of Terrestrial Magnetism.

By measuring minute variations in the isotopic composition of the rare earth elements neodymium and samarium in the rocks, O'Neil and Carlson determined that the rock samples range from 3.8 to 4.28 billion years old. The oldest dates came from rocks termed "faux amphibolite," which the researchers interpret to be ancient volcanic deposits.

"There have been older dates from Western Australia for isolated resistant mineral grains called zircons," says Carlson, "but these are the oldest whole rocks found so far." The oldest zircon dates are 4.36 billion years. Before this study, the oldest dated rocks were from a body of rock known as the Acasta Gneiss in the Northwest Territories, which are 4.03 billion years old. The Earth is 4.6 billion years old, and remnants of its early crust are extremely rare—most of it has been mashed and recycled into Earth's interior several times over by plate tectonics since the Earth formed.

The rocks are significant not only for their great age but also for their chemical composition, which resembles that of volcanic rocks in geologic settings where tectonic plates are crashing together. "This gives us an unprecedented glimpse of the processes that formed the early crust," says Carlson.

*Authors: Jonathan O'Neil, McGill University; Richard W. Carlson, Carnegie Institution; Don Francis, McGill University; Ross K. Stevenson, Université du Québec.

Richard Carlson | EurekAlert!
Further information:
http://www.ciw.edu

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>