藏东色礼岩体岩石地球化学特征及成因  

Geochemical Characteristics and Genesis of the Seli Intrusive Body in Eastern Tibet

作　　者：胡志宇[1] 王陆超 HU Zhi-yu;WANG Lu-chao(College of Civil Engineering and Architecture,Three Gorges University,Yichang Hubei 443002,China;The6th Geological Team of Jiangsu Bureau of Geology and Mineral Resources,Lianyungang Jiangsu 222023,China)

机构地区：[1]三峡大学土木与建筑学院,湖北宜昌443002 [2]江苏省地矿局第六地质大队,江苏连云港222023

出　　处：《矿物岩石地球化学通报》2018年第5期903-909,共7页Bulletin of Mineralogy, Petrology and Geochemistry

摘　　要：色礼岩体位于藏东芒康县打拉地区,是研究玉龙斑岩铜矿带含矿特征的重要对象。本文以色礼黑云母二长花岗斑岩为对象,对其进行了岩石学、岩石地球化学及锆石U-Pb年代学研究,并讨论了它的地球化学特征及其源区特征。研究结果显示,样品中的锆石具有明显的振荡环带和较高的Th/U值,属于典型的岩浆成因锆石,LA-ICP-MS锆石^206Pb/^238U年龄为(393±O.4)Ma,为始新世。岩石地球化学特征表明,色礼黑云母二长花岗斑岩具较高的SiO2含量和高钾、富碱的特征,其A/CNK值为0.89~0.95,为偏铝质钾玄岩系列;它的稀土元素配分模式为右倾型,具Eu弱负异常和弱的Ce正异常,表现为Nb、Ta、P、Zr、Ti、Hf等高场强元素相对亏损,相对富集Rb、K、Th、U等大离子亲石元素;色礼岩体形成于陆-陆碰撞造山环境,可能是由古老地壳部分熔融混入了少量新生地壳物质而形成的。The Seli intrusive body is located in the Dala area of Mangkang County,eastern Tibet.It is an important object for studying the characteristics of the Yulong porphyry copper beh.The Sell intrusive body consists mainly of biotite monzonitic granite porphyry.In this paper,we have undertaken petrological,petrogeochemical and zircon geochronological studies of the Sell body and discussed its geochemical characteristics and its origin.Its zircons have clear oscillatory zones in CL images as well as relatively high Th/U ratios,suggesting a typical magmatie origin.Zircon LA-ICP-MS dating yielded an age of (39.3±0.4)Ma,implying that the biotite monzonitic granite porphyry body was emplaced in Eocene.It is characterized with relatively high silica,high potassium,and abundant alkali,with A/CNK values of 0.89-0.95.It belongs to peraluminum shoshonite series.It has right declined REE patterns,with slightly negative Eu and positive Ce anomalies. It is relatively depleted in HFSE including Nb,Ta,P,Zr,Ti,andHf and relatively enriched in LILE including Rb,K, Th,and U.It is suggested that the Sell body could be formed in the continental-continental collision orogenic environment by the magma derived from the partial melting of major old crust mixed with minor juvenile crustal materials.

关 键 词：黑云母二长花岗斑岩 地球化学 锆石U-PB LA-ICP-MS 西藏色礼 

分 类 号：P597[天文地球—地球化学]