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Gold endowments of porphyry deposits controlled by precipitation efficiency.

  • Chiaradia M Department of Earth Sciences, University of Geneva Rue des Maraîchers 13, 1205, Geneva, Switzerland. Massimo.Chiaradia@unige.ch.
  • 2020-01-16
Published in:
  • Nature communications. - 2020
General Biochemistry, Genetics and Molecular Biology
General Physics and Astronomy
General Chemistry
English Porphyry deposits are natural suppliers of most copper and significant gold to our society. Whereas the Cu-richest (Au-poor) porphyries are related to Andean-type subduction and typical calc-alkaline magmatism, the Au-richest porphyries are associated with high-K calc-alkaline to alkaline magmatism in late to post-subduction or post-collision and extensional settings, and subordinately with calc-alkaline magmatism. The reasons behind these associations and the large variations in metal endowments of porphyry Cu-Au deposits remain obscure. Here, I show that porphyry Cu-Au deposits define two distinct trends in Au vs. Cu tonnage plots (Cu-rich and Au-rich). Metal endowments for both trends grow larger the longer the mineralization process. However, Au is precipitated at much higher rates in Au-rich than in Cu-rich porphyry deposits. Using Monte Carlo simulations of petrologic processes, I show that whereas Cu-rich porphyries require large amounts of magma and water to be formed, Au-rich porphyries are the result of a better efficiency of Au precipitation.
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  • English
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gold
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https://sonar.ch/global/documents/76476
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