Many large reserves of gold are thought to have been deposited when the stable interiors of Earth's continents — cratons — formed more than 2.5 billion years ago. The age of gold deposits in the North China Craton, however, implies that some of China's gold may have instead accumulated during the partial destruction of the craton.
Jian-Wei Li at the China University of Geoscience, Wuhan, and colleagues dated deposits of gold located in eastern parts of the North China Craton. They found that the gold was deposited between 154 and 119 million years ago, about 1.7 billion years after the North China Craton formed. Isotopic analyses of the gold deposits indicate a source from the mantle. The gold was deposited during a period of extensive volcanic activity, during which the eastern part of the North China Craton was stretched and extended. The researchers suggest that the vast volumes of gold accumulated when hot mantle material upwelled beneath the stretched eastern craton, as this part of the once-stable land mass was gradually broken up and destroyed.
Giant gold deposits could potentially have formed in other locations where Earth's outer shell has been exposed to intense destruction and volcanic activity.
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Whitchurch, A. Gold from destruction. Nature Geosci 5, 590 (2012). https://doi.org/10.1038/ngeo1576
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DOI: https://doi.org/10.1038/ngeo1576
