安徽宣城地区昆山岩体LA-ICP-MS锆石U-Pb年代学和岩石地球化学特征及地质意义  

LA-ICP-MS ZIRCON U-PB CHRONOLOGY AND PETROGEOCHEMICAL FEATURES OF THE KUNSHAN ROCK MASS IN THE XUANCHENG AREA,ANHUI PROVINCE AND THEIR GEOLOGICAL IMPLICATIONS

作　　者：周宇章[1] 金敏[1] 赵丽丽[1] 陆三明[1] 亓华胜 谢祖军[3] ZHOU Yu-zhang;JIN Min;ZHAO Li-li;LU San-ming;QI Hua-sheng;XIE Zu-jun(Public Geological Survey Management Center of Anhui Province,Hefei,Anhui 230091,China;University of Science and Technology of China,Hefei,Anhui 230026,China;No.322 Unit of Bureau of Geology and Mineral Exploration of Anhui Province,Ma'anshan,Anhui 243000,China)

机构地区：[1]安徽省公益性地质调查管理中心,安徽合肥230091 [2]中国科学技术大学,安徽合肥230026 [3]安徽省地质矿产勘查局322地质队,安徽马鞍山243000

出　　处：《安徽地质》2020年第2期81-88,104,共9页Geology of Anhui

基　　金：安徽省国土资源科技项目(2016-K-4);国家重大研发课题“长江中下游南陵-宣城矿集区三维综合探测与深部成矿预测”联合资助。

摘　　要：安徽宣城是长江中下游成矿带近年来新发现的矿集区,区内广泛出露与成矿作用有着密切关系的中酸性侵入岩,其中,昆山岩体是区内出露面积最大的岩体,岩体周围分布着许多重要的铜金、铅锌、硫铁等矿床。为了探讨昆山岩体的成因及构造意义,本文对该岩体开展了岩石学、锆石U-Pb年代学、岩石地球化学等方面的研究。研究结果表明,该岩体主要由辉石闪长岩组成,LA-ICP-MS锆石U-Pb年龄为(131.8±2.1)Ma,反映岩体为白垩世侵位。岩石轻稀土元素富集而重稀土元素亏损,Eu呈轻微的负异常,富集Rb、Ba、Th、U、K等大离子亲石元素,相对亏损Nb、Ta、P等高场强元素,反映其源岩可能主要为壳幔混合源,岩体是由古老地壳部分熔融形成的长英质岩浆与起源于富集地幔的富碱玄武质岩浆混合后形成。Xuancheng,Anhui Province,is an ore concentration area newly discovered in the middle and lower reaches of the Yangtze River metallogenic belt in recent years.The intermediate-acid intrusive rocks that are closely related to mineralization are widely exposed in the area.The Kunshan rock mass is most exposed in the area,and is surrounded by many important copper,gold,lead,zinc and iron sulfide deposits.In order to explore the genesis and structural significance of the Kunshan rock mass,this paper studies the rock mass in terms of petrology,zircon U-Pb chronology and petrogeochemistry.The results show that the rock mass is mainly composed of pyroxene diorite,with LA-ICP-MS U-Pb age of zircon being(131.8±2.1)Ma,indicating its Cretaceous emplacement.The rocks are rich in light rare earth elements and poor in heavy rare earth elements with slightly negative Eu anomaly,having high Rb,Ba,Th,U,K and other large ion lithophile elements,and relatively low Nb,Ta,P high field strength elements,probably reflecting that the source rock is mainly a mixture of old felsic magma formed by partial melting of the crust and alkali-rich basaltic magma derived from the enriched mantle.

关 键 词：锆石U-PB年代学 岩石地球化学 岩石成因 构造意义 昆山岩体 宣城 

分 类 号：P535[天文地球—古生物学与地层学]