地质学报2024，Vol.98Issue(1)：181-199,中插28-中插33,25.DOI:10.19762/j.cnki.dizhixuebao.2023019
锆石氧逸度对相山地区火山岩型铀矿床成矿母岩判别的指示意义
Zircon oxygen fugacity as a tracer to distinguish the parent rock volcanic-hosted uranium mineralization in the Xiangshan area,South China
摘要
Abstract
Volcanic-intrusive complexes are widely distributed in South China,and some of them are accompanied by volcanic-related uranium deposits.Therefore,distinguishing between ore-bearing and ore-free rocks has become an important hot topic in the field of ore deposits.This study focuses on examining the composition of trace elements in zircon using LA-ICP-MS,determining the U-Pb ages,and analyzing the characteristics of whole-rock trace elements in both ore-bearing volcanic-intrusive rocks and ore-free intrusive rocks in the Xiangshan area of South China.The results show that the ages of ore-bearing porphyroclastic lava(Zoujiashan)and granite porphyry(Yunji)are 132.8±1.5 Ma and 133.7±1.6 Ma,respectively.Correspondingly,the ages of the ore-free Qiqin and Taoxi granite porphyry are 134.9±1.3 Ma and 133.3±1.3 Ma,respectively.Those ages of the ore-bearing and ore-free plutons are basically synchronous within the error range.The ratios of zircon Ce4+/Ce3+in the ore-bearing and ore-free rocks range from high to low as follows:Zoujiashan 22.12～68.75(average 45.61),Yunji 19.02～43.48(average 27.64),Qiqin 7.99～22.03(average 15.63),Taoxi 9.70～22.40(average 16.19).The results obtained from the zircon Ti content thermometer suggest that the zircon crystallization temperature of the ore-bearing rocks is relatively higher than that of the ore-free rocks.Furthermore,when considering the lattice strain model and zircon Ti thermometer,it can be inferred that the absolute oxygen fugacity of the former is also higher than that of the latter.This study indicates that the Ce4+/Ce34 ratio of zircon in the ore-bearing volcanic-intrusive rock in the Xiangshan area generally exceeds 22.Therefore,we propose that the oxygen fugacity of zircon can be used as a potential indicator to determine whether the rock shows ore-bearing characteristics.Moreover,the uranium content of the whole rock in both the ore-bearing and ore-free rocks shows a significant positive correlation with the oxygen fugacity.This suggests that the high oxygen fugacity of the ore-bearing rocks may indicate a higher uranium content in the parent magma of these rocks.Based on previous research,it is suggested that the oxygen fugacity of uranium-bearing rocks is significantly lower than that of porphyry copper-molybdenum ore deposits,but similar to that of granite-type tungsten ore and volcanic rock-type silver-lead-zinc ore.Therefore,the level of oxygen fugacity serves as an important constraint on the differential mineralization types of Cu-Mo,W-Mo,U,and Ag-Pb-Zn ore-bearing rocks,which may indirectly reflect a substantial contribution from mantle materials.关键词
氧逸度/锆石微量元素/相山铀矿/控矿因素Key words
oxygen fugacity/zircon trace elements/Xiangshan uranium deposit/ore-controllingfactor引用本文复制引用
降珂楠,骆金诚,钟福军,刘国奇,张笑天,江小燕..锆石氧逸度对相山地区火山岩型铀矿床成矿母岩判别的指示意义[J].地质学报,2024,98(1):181-199,中插28-中插33,25.基金项目
本文为国家自然科学基金项目(编号41873057,41603051)和贵州省基金项目(编号黔科合基础[2018]1423)联合资助的成果. （编号41873057,41603051）
