Bristol, UK (SPX) Jan 17, 2011
The continental crust is the principal record of conditions on the Earth for the last 4.4 billion years. Its formation modified the composition of the mantle and the atmosphere, it supports life, and it remains a sink for carbon dioxide through weathering and erosion.
The continental crust therefore has had a key role in the evolution of the Earth, and yet the timing of its generation remains the topic of considerable debate.
It is widely believed that the juvenile continental crust has grown from the depleted upper mantle. One common way to assess when new crust was formed is to determine the radiogenic isotope composition of any crustal sample, and to compare its isotope signature with that of the depleted mantle.
In other words, radiogenic isotopes can be used to calculate 'model ages' of crust formation, which represent the time since a crustal sample was separated from its mantle source.
The concept of 'model age' has been widely used in crustal evolution studies for the last three decades.
However it is increasingly clear that using the isotope composition of the depleted mantle as a reference for the calculation of model ages of continental crust generation can lead to incomplete interpretations.
In a paper published in Science, Dr Bruno Dhuime of Bristol's School of Earth Sciences and colleagues describe a new methodology for the calculation of model ages, based on the isotope composition of the average new continental crust.
Dr Dhuime said: "Ages calculated this way are significantly younger than model ages calculated from the isotope composition of the depleted mantle. New ages obtained are more consistent with the geological record, which opens new perspectives in crustal evolution studies based on radiogenic isotopes."
Share This Article With Planet Earth
University of Bristol
Dirt, rocks and all the stuff we stand on firmly
Discovering Potential Solutions To New England Roadside Erosion
Kingston RI (SPX) Jan 04, 2011
Erosion is a significant problem on highway embankments in New England. To mitigate erosion on the regions' highways, slopes are seeded with a grass-legume mixture that usually including red fescue, a grass preferred for its drought-tolerance and ability to thrive in acidic, infertile soil. "A mixture of red fescue, perennial ryegrass, and kentucky bluegrass is planted to stabilize the soi ... read more
Study Explores How People Respond To Climate Disasters|
Fresh rain hampers Brazil rescue, death toll rises
Sri Lanka mine fears as floods recede
Struggling Haiti faces crucial week in politics
Method Discovered To Determine When Metals Reach End Of Life
Launch of Murdoch's The Daily delayed: report
Google buys eBook Technologies
Direct Observation Of Carbon Monoxide Binding To Metal-Porphyrines
Dramatic Ocean Circulation Changes Revealed
Ocean Bacteria Recycles Iron
Lake Erie Hypoxic Zone Doesn't Affect All Fish The Same
FAO unveils new guidelines on fishing discards
Mountain Glacier Melt To Contribute 12 Centimetres To World Sea-Level Increases By 2100
Greenpeace slams BP over Russia deal to explore Arctic
Warming to devastate glaciers, Antarctic icesheet - studies
Russia reaches first stranded fishermen
World is 'one poor harvest' from chaos, new book warns
Walker's World: The U.S., China and food
Food Prices Insulate Agriculture Sector From Wider Economy Woes
GM Chickens That Don't Transmit Bird Flu Developed
Brazil flood death toll keeps climbing
Australia towns face once-in-200-year flood
Mount Etna Bursts Into Life
Brazil mourns as flood death toll climbs
Sierra Leone evicts civilians from crowded army barracks
Questions over Africa's appetite for arms in I. Coast
Four exiled Rwandan opponents slam jail sentences
Indian sailors jailed in Somalia over illegal charcoal
Climate tied to rise, fall of cultures
Impact Of Traffic Noise On Sleep Patterns
Humans First Wore Clothes 170,000 Years Ago
Publication of ESP study causes furor
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|