When and how continents formed
By ANIFriday, January 14, 2011
WASHINGTON - A new study attempts to bring to rest a long- standing debate - when and how continents really formed.
The continental crust 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.
However, the timing of its generation remains the topic of considerable debate.
One way to determine the time is to find the radiogenic isotope composition of any crustal sample, and to compare its isotope signature with that of the depleted mantle.
However, after being used in many studies, it is 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.
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.
“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,” he said.
The paper is published today in Science. (ANI)
