沉积与特提斯地质2024，Vol.44Issue(2)：421-436,16.DOI:10.19826/j.cnki.1009-3850.2023.11004
滇西北浪都夕卡岩矿床致矿岩体的岩石地球化学、年代学、Sr-Nd-Pb同位素组成及其地质意义
Petrogeochemistry,chronology,Sr-Nd-Pb isotopic compositions,and geological significance of the ore-causative intrusion in the Langdu skarn deposit,northwest Yunnan
摘要
Abstract
The Langdu intrusion in northwestern Yunnan is located in the Zhongdian arc of the southern Yidun terrane and it belongs to the ore-causative intrusion of Langdu skarn-type copper deposit,spatially.This study focuses on the quartz-diorite porphyry within the Langdu ore-bearing intrusion and investigates its zircon SIMS U-Pb dating,rock geochemistry,and Sr-Nd-Pb isotopic composition.The zircon U-Pb dating results reveal a crystallization age of 219.2±1.8 Ma(2σ,MSWD=1.3,n=13)for the Langdu quartz-diorite porphyry,which is consistent with the late Triassic intrusive rocks in the Zhongdian arc.The Langdu quartz-diorite porphyry exhibits medium SiO2(60.42%-66.44% ),high Al2O3(14.56%-16% ),and high K2O(3.49%-4.49% )contents.It is characterized by enrichment of LREE and large ion lithophile elements such as Rb,Ba,and Sr,and relative depletion of HREE and high field strength elements such as Ta,Nb,and Ti,belonging to the high-K calc-alkaline series.Additionally,the initial 87Sr/86Sr ratios of the Langdu quartz-diorite porphyry range from 0.705 4 to 0.706 1,and εNd(t)values range from-3.5 to-2.5.All samples are plotted near the orogenic evolution line on the Pb isotope evolutionary diagram.Combining the petrological,geochemical,and isotopic characteristics of the Langdu quartz-diorite porphyry,this study suggests that the Langdu ore-bearing intrusion formed in relation to the westward subduction and accretion of late Triassic Garez-Litang oceanic crust.It was a product of partial melting of the metasomatized mantle,mixed with lower crustal material during its ascent,and experienced intense fractional crystallization.The high Sr/Y and high V/Sc ratios of the Langdu quartz-diorite porphyry indicate the characteristics of high-water content and relatively high oxygen fugacity in the magma,which are probably key factors controlling the formation of the porphyry-skarn copper deposit in this region.关键词
浪都/致矿岩体/岩石地球化学/锆石U-Pb年龄/Sr-Nd-Pb同位素Key words
Langdu/ore-bearing intrusion/rock geochemistry/zircon U-Pb age/Sr-Nd-Pb isotopes分类
天文与地球科学引用本文复制引用
莫雷,冷成彪,沈啟武,陈喜连,吴练荣,张传昱,董桥峰,苏肖宇,施宝生,余海军..滇西北浪都夕卡岩矿床致矿岩体的岩石地球化学、年代学、Sr-Nd-Pb同位素组成及其地质意义[J].沉积与特提斯地质,2024,44(2):421-436,16.基金项目
第二次青藏高原综合科学考察研究(2021QZKK0301) （2021QZKK0301）
国家自然科学基金项目(42102098,42173026) （42102098,42173026）
云南迪庆有色金属责任公司科研项目(DQYS-SCB-08-(2022)031) （DQYS-SCB-08-(2022）
东华理工大学研究生创新基金(YC2023-S550) （YC2023-S550）
