地质学报2018，Vol.92Issue(6)：1280-1296,17.
滇中老街子Pb-Ag多金属矿床的成矿时代及成矿动力学背景探讨:来自硫化物Re-Os同位素证据
The Metallogenic Age and Geodynamic Setting of the Laojiezi Pb-Ag Polymetallic Deposit, Central Yunnan Province:Evidence from Re-Os Isotope of Sulfides
摘要
Abstract
The Laojiezi Pb-Ag deposit,located in the middle section of the Cenozoic Red River-Ailaoshan alkali-rich porphyry belt,is the typical alkali-rich volcanic-magmatic hydrothermal deposit in central Yunnan province.A 70-m-wide syenite porphyry and molybdenite-pyrite vein with high Cu-Mo abnormal pyritization was firstly discovered in the deep part of the deposits (3 # vein of 2073 level).It is believed that obvious alkali-rich porphyry and magmatic-hydrothermal Cu-Mo superimposed mineralization occurs at depth of the deposit.This study conducted Re-Os isotopic analysis for molybdenite-pyrite samples from molybdenite-pyrite veins,pyrite-galena veins and high Cu-Mo syenite porphyry from deep adits in the Laojiezi Pb-Ag deposits.An isochron age of 33.71 ± 0.29Ma and a weighted average age of 33.99 ± 0.22Ma were obtained for molybdenite,indicating that the mineralization of the Pb-Ag polymetallic deposit took place in Oligocene,which is consistent with the diagenetic age of the syenite porphyry.The initial Os value of 0.3049 ～ 1.5549 and the γOs value of 140.5 ～ 1126 suggest that the metallogenic material was derived from partial melting of the crust-mantle transition layer.The metallogenic age of the Laojiezi porphyry Pb-Ag polymetallic deposit is roughly the same as that (30 ～ 40 Ma) of regional alkali-rich porphyry and magmatic hydrothermal polymetallic deposits.It shows that,after the collision between the India plate and Eurasia plate,the change of tectonic stress field resulted in large-scale strike-slip faulting system,which induced partial melting of crust-mantle transition zone within the stable cratons,forming alkali-rich intrusive rocks and metallogenic fluids,and the fluid formed alkali-rich porphyry and magmatic-hydrothermal polymetallic deposits along the weak structures.关键词
滇中/老街子Pb-Ag多金属矿床/Re-Os同位素/成矿动力学Key words
Central Yunnan/Laojiezi Pb-Ag deposits/Re-Os isotope/metallogenic geodynamic引用本文复制引用
江小均,严清高,李文昌,李超,吴鹏,管申进,余海军,李金龙..滇中老街子Pb-Ag多金属矿床的成矿时代及成矿动力学背景探讨:来自硫化物Re-Os同位素证据[J].地质学报,2018,92(6):1280-1296,17.基金项目
本文为北京离子探针中心开放基金(DDC15-016)、国家重点基础研究发展计划(973计划)(编号:2015CB452605)、云南省应用基础研究计划青年(2016DF031)和云南省科技领军人才培养计划(编号:2013HA001)等项目联合资助. （DDC15-016）
