Continental crust is the main recording the condition of the Earth for 4.4 billion years. Formation and change the composition of the mantle layer of the atmosphere, it supports life, and remains as the washing of carbon dioxide through the weather and erosion.
A new way to calculate the age of the Earth’s crust has been developed by researchers from the University of Bristol and the University of St. Andrews.
Continental crust is the main recording the condition of the Earth for 4.4 billion years. Formation and change the composition of the mantle layer of the atmosphere, it supports life, and remains as the washing of carbon dioxide through the weather and erosion. Therefore, the continental crust has a major role in the evolution of the Earth, and yet the timing thereof remains a topic of hot debate.
It was widely believed that the young continental crust has grown from a depleted upper mantle. One common way to know when new crust is formed by determining the isotopic composition of the sample radiogenic crust, and compared the characteristics of isotopes with a coat that has been thinned. In other words, radiogenicisotopes can be used to calculate ‘model ages’ crust formation, which represents the time since the crust samples separated from the source mantle.
The concept of ‘model age’ has been widely used in studies of crustal evolution during the last three decades. But it became clear that using the isotopic composition of the depleted mantle as a reference calculation model of the continental crust derived age may lead to incomplete interpretations.
In a paper published yesterday in the journal Science, Dr. Bruno Dhuime of Bristol School of Earth Sciences and his colleagues describe a new methodology for the calculation of the model ages, based on the isotopic composition of the average new continental crust.
Dr. Dhuime said: “The age is calculated in this way are significantly younger than the model ages calculated from the isotopic composition of the depleted mantle. New age obtained more consistent with the geological record, which opens new perspectives in crustal evolution studies based on isotope radiogenic.” Similarly, as quoted from Physorg (01/13/11).