中国地质2024，Vol.51Issue(2)：385-398,14.DOI:10.12029/gc20201104002
西藏拿若铜(金)矿床隐爆角砾岩对成矿时代的约束
Constraints on metallogenic age from cryptoexplosive breccia in Naruo Cu(Au)deposit,Xizang
摘要
Abstract
This paper is the result of mineral exploration engineering. [Objective]The Naruo deposit is one of four super large deposits in Duolong ore district.It is composed of porphyry and breccia type orebodies.Previous researches have focused on porphyry orebody,while the research on cryptoexplosive breccia ore bodies is relatively weak.The temporal relationship between cryptic explosion processes and mineralization remains inadequately studied.The cryptoexplosive breccia is generally produced in a cylindrical shape,with the breccia composed of feldspar quartz sandstone and granodiorite porphyry,and the cement mainly composed of rock powder.[Methods]This study is to explore the age relationship between the formation and mineralization of cryptoexplosive breccia through chronological evidence.[Results]Zircon mineralogy shows that the zircon edge of the granite diorite porphyry(NR1)is characterized by dissolution,weak oscillation zone,and incomplete recrystallization.Zircons in cement(NR1)is characterized by fine crystalline form,clear oscillatory zone.The trace element characteristics of these two types of zircons show that the source of two stages of magma is continental crust.The rare earth distribution curves are relatively steep,with enrichment of heavy rare earth elements,loss of light rare earth elements,significant positive Ce and negative Eu anomalies.LA-ICP-MS zircon U-Pb dating results show that the zircon 206Pb/238U age of granite diorite porphyry is between 117.3 Ma and 125.4 Ma,with weighted average age of(120.8±1.4)Ma,indicating the diagenetic age of 120.8 Ma.The zircon 206Pb/238U age of cement is between 113.5 Ma and 119.9 Ma,with weighted average age of(116.4±1.2)Ma,indicating the cryptoexplosive age of 116.4 Ma.[Conclusions]The results in this study show two stages of diagenesis in Naruo deposit,～120 Ma and～117 Ma,respectively.Mineralization occurred between 116 Ma and 117 Ma,rather than～120 Ma.The chronological data shows that the mineralization and cryptoexplosion are controlled by contemporaneous magmatism,with cryptoexplosion occurring first and mineralization occurring later,and there are differences in the time and space of magma evolution.关键词
锆石U-Pb定年/隐爆时代/成岩成矿时代/隐爆角砾岩/拿若/西藏/矿产勘查工程Key words
zircon U-Pb dating/cryptoexplosive time/diagenesis and mineralization/cryptoexplosive breccias/Naruo/Xizang/mineral exploration engineering分类
天文与地球科学引用本文复制引用
高轲,宋扬,刘治博,杨欢欢,林彬,李发桥..西藏拿若铜(金)矿床隐爆角砾岩对成矿时代的约束[J].中国地质,2024,51(2):385-398,14.基金项目
中国地质调查局项目(DD20242518、DD20230031、DD20190167、DD20190147),国家自然科学基金项目(41702080、91955208)以及国家重点研发计划深地资源开采项目(2018YFC0604103)联合资助. Supported by the projects of China Geological Survey(No.DD20242518,No.DD20230031,No.DD20190167,No.DD20190147),National Natural Science Foundation of China(No.41702080,No.91955208),National Key Research and Development Program(No.2018YFC0604103). （DD20242518、DD20230031、DD20190167、DD20190147）
