西藏朱诺斑岩铜矿石英闪长斑岩锆石LA-ICP-MSU-Pb定年及Lu-Hf同位素研究  

Study of Quartz Diorite Porphyry by LA-ICP-MS U-Pb Dating and Lu-Hf Isotopic Tracing in the Zhunuo Porphyry Deposit, Tibet

作　　者：张丽[1] 黄勇[1] 李光明[1] 董随亮[1] 侯春秋[1] 

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《矿物学报》2016年第1期143-149,共7页Acta Mineralogica Sinica

基　　金：西藏米拉山铜矿整装勘查区专项填图与技术应用示范(编号:12120114050501);西藏扎西康铅锌多金属矿整装勘查区专项填图与技术应用示范(编号:1212011221073)

摘　　要：朱诺斑岩铜矿床位于冈底斯成矿带的中段西部,是近年来新发现的大型斑岩铜矿床,矿体受控于新生代复式多期岩浆活动,成矿年龄为13.72 Ma,前人主要针对中新世岩浆活动开展研究,而对矿区另一类含矿石英闪长斑岩却鲜有报道,钻孔编录以及镜下鉴定表明石英闪长斑岩可能提供了部分成矿物质,因此详细开展含矿石英闪长斑岩的研究有利于拓展矿区的找矿方向。通过开展石英闪长斑岩原位锆石LA-ICP-MS U-Pb定年和Lu-Hf同位素测试。结果表明测试样品的加权平均年龄为51.47±0.6 Ma,代表该岩体的岩浆结晶年龄为始新世。锆石εHf（t）值介于-5.4-0.8,平均值为-2.4,^176Hf/^177Hf比值为0.28259-0.28276,平均值为0.28268,二阶段Hf模式年龄（TDM2）介于1.1-1.4 Ga之间,平均值为1.3 Ga。Lu-Hf同位素结果反映朱诺地区始新世岩体具有明显的古老地壳印记,岩浆源区为中-古元古代地壳物质并混染有少量的年轻基性物质,指示在拉萨地体南部,谢通门以西的朱诺地区存在中-古元古代结晶基地。The Zhunuo porphyry copper deposit is newly discovered porphyry deposit and situated in the mid-western part of the Gangdese metallogenic belt. The mineralization is associated with Miocene multi-intrusions. The mineralization time is 13.72 Ma. The previous studies are mainly focus on the Miocene intrusions. However, one of ore-bearing stock is still poorly studied, which contains lots of minerals bearing fluid inclusion within quartz phneocrysts, indication another possibly mineralization time and implication for furture exploration. According to research of Zircon LA-ICP-MS U-Pb dating and Lu-Hf isotopic tracing, we obtained the age of quartz diorite porphyry is 51.47±0.6 Ma, representing crystallization age of the intrusions. The sample have Zircon εHf（t） values of-5.36-0.78（the average is-2.358）, ^176Hf/^177 Hf values of 0.282590-0.282764（the average is 0.282675）, and TDM2 values of 1.1-1.4 Ga（the average is 1.3 Ma）. The data show the rock is derived from the Meso-Paleoproterozoic crust materials with minor younger mafic materials. Therefore, we infered that Meso-Paleoproterozoic crust materials also exist at south part the Lhasa terrane.

关 键 词：西藏 朱诺斑岩铜矿 石英闪长斑岩 年代学 同位素示踪 

分 类 号：P581[天文地球—岩石学] P597[天文地球—地质学]