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藏东玉龙超大型斑岩铜矿床是目前西藏发现的最大斑岩铜矿床,含铜岩体主要由早期石英二长斑岩及晚期正长花岗斑岩组成。本文用LA-ICP-MS法测定早期石英二长斑岩及晚期正长花岗斑岩锆石U-Pb年龄及Ar-Ar法测定钾质蚀变带黑云母的Ar-Ar年龄,发现玉龙含矿斑岩体早期石英二长斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.3Ma,MSWD=0.92)与晚期正长花岗斑岩锆石Lu0003A-ICP-MS U-Pb年龄(41.3±0.2Ma,MSWD=1.24)基本相同,也和黑云母Ar-Ar坪年龄(41.7±0.8Ma)及等时线年龄(41.3±0.8Ma)在误差范围内一致。玉龙斑岩铜矿早期及晚期岩体锆石U-Pb年龄一致表明含矿岩体在地质上的早期及晚期主要是岩浆在较短时间内脉动侵入所致。玉龙含矿岩体锆石U-pb年龄(封闭温度约800℃)、~(39)Ar-~(40)Ar年龄(封闭温度约300℃)及前人获得的Re-0s年龄40.1±1.8Ma(封闭温度约500℃)在误差范围内基本一致,表明含矿岩体岩体快速冷却,玉龙超大型斑岩铜矿床成岩成矿系统时间跨度小于1Ma。
The Yulong super-large porphyry copper deposit in Tibet is the largest porphyry copper deposit discovered in Tibet at present. The copper-bearing rock mass is mainly composed of early quartz monzogranite and late-period orthoclase granite porphyry. In this paper, zircon U-Pb ages of early quartz monzogranite and late orthoclase granite porphyry were determined by LA-ICP-MS and Ar-Ar ages of Arg were determined by Ar-Ar method. It was found that Yulong The LA-ICP-MS U-Pb dating of the early quartz porphyry in the ore-bearing porphyries (41.3 ± 0.3Ma, MSWD = 0.92) is consistent with that of the late orthoclase granite porphyry L u0003A-ICP-MS U -Pb age (41.3 ± 0.2Ma, MSWD = 1.24) are basically the same, and also consistent with the Ar-Ar Ping age (41.7 ± 0.8Ma) and isochron age (41.3 ± 0.8Ma) of biotite in the error range. The consistent U-Pb ages of early and late zircons of the Yulong porphyry copper deposit show that the early and late geological changes of the ore-bearing rock mass are mainly caused by the pulsation intrusion of magma in a relatively short period of time. The zircon U-Pb ages of Yulong ore-bearing rock mass (sealing temperature is about 800 ℃), ~ (39) Ar- ~ (40Ar) age (sealing temperature is about 300 ℃) and the Re-0s age 40.1 ± 1.8 Ma (sealing temperature about 500 ℃) are basically the same within the error range, indicating that the ore-bearing rock masses are rapidly cooled, and the time scale of diagenesis and mineralization of the Yulong superlarge porphyry copper deposits is less than 1Ma.