Geochronology and Geochemistry of Naruo Porphyry Cu (Au) Deposit in Duolong Ore-Concentrated Area, Tibet, and Their Geological Significance
Ding Shuai
Tang Juxing
Zheng Wenbao
Yang Chao
Zhang Zhi
Wang Qin
Wang Yiyun
Abstract：As the most important part of Bangong Lake-Nujiang River metallogenic belt,the Duolong ore-concentrated area is characterized by the occurrence of huge mineralization scale,extended time span and complex forming process,resulting in controversial understanding of its petrogenesis and tectonics and those of related deposits.To address this problem,this study firstly presents new data of LA ICP-MS zircon U-Pb age,whole-rock geochemistry,and in situ zircon Hf isotopes for the mineralization-associated granite porphyry in Naruo porphyry copper (gold) deposit,and secondly we make a detailed comparison with research results of other porphyry deposits in Duolong area to find out the tectonic setting,petrogenesis and geodynamic processes of the mineralization-associated porphyry in Duolong area.The test results show that the age of the Naruo Cu (Au) deposit formation is consistent with that of other deposits in Duolong area formed at Early Cretaceous about 120 Ma.All the main intrusive rocks have similar lithogeochemical characteristics,for they all show the relative enrichment in light rare earth elements (LREE) and large-ion lithophile elements (LILE:Rb,Ba,K,etc.),relatively depleted in heavy rare earth elements (HREE) and high field strength elements (HFSE:Nb,Ta,Zr,Hf,etc.).Moreover,the granite porphyry shows positive εHf (t) values between 1.38-7.37,and two-stage model ages of zircons are 707-1 086 Ma.The results suggest that the formation of porphyry-epithermal copper (gold) deposit in Duolong ore-concentrated area is dominated by northward subduction of the Bangongcuo Tethys plate beneath Qiangtang block at Early Cretaceous.When the subducted oceanic crust reached 50-70 km underground and generated different degrees of phase transformation,which leads to melt produced by dehydration of amphibole minerals metasomatized mantle wedge and induced mantle partial melting produced magmatic arc.Those deposits occurred in a continental arc tectonic setting which is similar to the continental margin arc environment of the ocean-continent suhduction setting of the Andes metallogenic belt in South America.
Keywords：Naruo copper (gold) depositgeochronologygeochemistryHf zircon isotopecontinental arcdepleted mantle
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：23( 1-23 )