The age of copper

ARTICLE In MINERALIUM DEPOSITA : First direct dating of a copper deposit

An IRD team and its partners - including Marc Poujol (Géosciences Rennes) - carry out the first direct dating of a copper deposit. By analysing this mineral from the Atacama Desert in Chile, scientists are making progress in understanding the climate and terrain of this region. The results are published in Mineralia Deposita in March 2020.
Located in northern Chile, the Atacama Desert is the driest region in the world. It is also the source of nearly a third of the world’s copper production. This precious Chilean ore is the fruit of two successive processes: primary mineralization called hypogen, in depth, linked to the magmatic ascents of cupriferous porphyry, then, on the surface, secondary mineralization called supergenous due to erosion and leaching by rainwater. It is on these that Zia Steven Kahou, Ivorian Phd student in geology at the Geosciences Environnement Toulouse (GET) laboratory, and an international team of researchers made a world first. “We did the direct dating of supergenous copper mineralization using an original method,” says Zia Steven Kahou, who made this topic the focus of her thesis, which began in 2017. Until now, only indirect processes, that is to say the dating of neighbouring minerals, were used to date copper. “We used an existing method to apply it to new minerals, something that no one had tried on this kind of minerals before,” says Stéphanie Brichau, geologist at the IRD at GET and co-director of the thesis.

Note that the dating protocol for these copper mineralization was first developed at Géosciences Rennes, by laser ablation ICP-MS of the OSUR Geohelis platform, controlled by Marc Poujol.

Atacama - © Marc poujol

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Kahou, Z.S., Brichau, S., Poujol, M. et al. First U-Pb LA-ICP-MS in situ dating of supergene copper mineralization: case study in the Chuquicamata mining district, Atacama Desert, Chile. Miner Deposita (2020).