A new way to calculate the age of the earth's crust has been developed by researchers at the Universities of Bristol and St Andrews . The continental crust is the main record of conditions on Earth during the last 4,400 million years. Your training changed the composition of the mantle and the atmosphere, and remains a sink for carbon dioxide through erosion. Therefore, the continental crust has played a key role in the evolution of the Earth, however, the timing of its formation remains a subject of considerable debate.
is a widely held belief that young continental crust grew from depleted upper mantle. A common way to assess when it formed a portion of the cortex is to determine the radiogenic isotopic composition of any sample of it, and compare their isotopic signature of depleted mantle. In other words, radiogenic isotopes can be used to calculate the ages of the formation of the studied portion of the cortex, representing that portion when separated from its source in the mantle.
The concept of "old model" has been widely used over the past three decades in studies of the evolution of the crust. However, it is increasingly clear that using the isotopic composition of depleted mantle as the reference for model ages of the generation of continental crust, can result in incomplete interpretations.
In a new study, the team of Bruno Dhuime (University of Bristol) has set up a new methodology for the calculation of model ages, based on the isotopic composition typical of the new continental crust.
ages calculated in this way are significantly lower than the model ages calculated from the isotopic composition of depleted mantle. The new ages obtained agree better with the geological record, which opens new perspectives for studies on the evolution of the crust based on radiogenic isotopes.
Carla Gallo
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