Massimo Chiaradia (University of Geneva) has been selected as the 2020 SEG Thayer Lindsley Visiting Lecturer on the basis of widely recognized expertise in a field of economic geology. Moreover, he published a new paper in Nature Communication
Massimo Chiaradia (University of Geneva) has been selected as the 2020 SEG Thayer Lindsley Visiting Lecturer on the basis of widely recognized expertise in a field of economic geology.
He also published in Nature Communication, see the abstract bellow:
Precipitation efficiency controls gold endowments in porphyry deposits
Porphyry copper-gold deposits are natural suppliers of most copper and significant gold to our society. They are large volume, low-grade disseminations formed by precipitation of copper and gold from fluids of magmatic origin. 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 of these associations and of 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 versus Cu tonnage plots (Cu-rich and Au-rich). Metal endowments for both trends grow larger the longer the mineralization process is. 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.