Optimal magmatic oxidation conditions for giant porphyry copper deposits  

形成巨型斑岩铜矿床的最优岩浆氧逸度

作　　者：Dian-Zhong Wang Jing-Jing Zhu Ruizhong Hu Massimo Chiaradia Xianwu Bi Ming-Liang Huang 汪殿钟;朱经经;胡瑞忠;Massimo Chiaradia;毕献武;黄明亮

机构地区：[1]State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Earth Sciences,University of Geneva,Geneva,1205,Switzerland

出　　处：《Science Bulletin》2025年第6期960-969,共10页科学通报(英文版)

基　　金：supported by the National Key Research and Development Program of China(2022YFC2903303);the Strategic Priority Research Program of Chinese Academy of Sciences(XDA0430301);the National Natural Science Foundation of China(42222206,42202104,42073047,and 42121003);the Hundred Talent Plan of the Chinese Academy of Sciences.

摘　　要：It is widely accepted that moderately to highly oxidized magmas are needed to form porphyry copper deposits(PCDs).However,only a few studies have attempted to investigate the effects of variable magmatic fO2 values on the formation of PCDs.Based on previously published studies,the magma oxygen fugacity of giant PCDs is mainly concentrated betweenΔFMQ−0.5 andΔFMQ+2.5,with the first quartile,median,and third quartile being+0.8,+1.3,and+1.7,respectively.In this work,we have carried out numerical modeling,which shows that the S^(2−)used to precipitate Cu accounts for approximately 90%of total sulfur atΔFMQ+1 but drops to 33%–38%and 15%–25%atΔFMQ+2 andΔFMQ+3,respectively.This leads to a decrease of 88%–96%in Cu precipitation efficiencies fromΔFMQ+1 toΔFMQ+3.Our petrological model further shows that the maximum Cu precipitation efficiency(and,therefore,Cu endowments)occurs at aroundΔFMQ+1.We,therefore,highlight that moderately oxidized magma(ΔFMQ=∼1)rather than highly oxidized ones(ΔFMQ>∼2)is optimal for the generation of giant PCDs.

关 键 词：Porphyry copper deposits Magmatic oxygen fugacity Precipitation efficiency 

分 类 号：P618.41[天文地球—矿床学]