江西东乡花岗斑岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义  

Geochemical features and LA-ICP-MS zircon U-Pb ages of the granite porphyry in the Dongxiang copper deposit of Jiangxi Province and their geological significance

作　　者：欧阳学财 狄永军[1] 张达[1] 徐洋[3] 杨秋[1] 王守营 陈杰[1] 杜斌[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]江西省核工业地质局266大队,江西南昌330038 [3]中国地质科学院矿产资源研究所,北京100037

出　　处：《地质通报》2016年第11期1869-1883,共15页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212011220557)

摘　　要：通过对东乡铜矿花岗斑岩进行岩石地球化学特征、锆石U-Pb定年研究，探讨其岩石成因、构造环境、形成时代与成矿的关系。东乡花岗斑岩的LA-ICP-MS锆石U-Pb年龄为156.4±1.5-161±1.0Ma。该岩体为高钾钙碱性系列，轻稀土元素富集，重稀土元素较亏损，具有明显的负Eu异常。微量元素富集大离子亲石元素，而亏损高场强元素。地球化学特征表明，东乡岩体形成于碰撞构造环境，岩浆来源于地幔，但形成演化期间经历了地壳物质的同化混染。该区矿石与花岗斑岩的稀土元素配分曲线存在一定的相似性，且成矿时间与岩浆侵入时间相近，表明岩浆侵入对东乡铜矿床的形成具有重要贡献。In this paper, the authors investigated petrogenesis, tectonic setting, emplacement timing and metallogeny of the granite porphyry based on its petro-geochemistry and zircon U-Pb geochronology. The LA-ICP-MS zircon U-Pb dating of the granite porphyry yielded ages of 156.4±1.5~161.0±1.0Ma, indicating that the granite porphyry was emplaced during the Yanshannian period. The granite porphyry is characterized by high-K calc-alkaline series, enrichment of LREE and depletion of HREE. The REE curves show negative Eu anomaly. The granite porphyry is enriched in large ion lithophile elements and depleted in high field strength elements. The petro-geochemical analysis shows that the Dongxiang granite porphyry was formed in a plate collisional environment and that crustal contamination was involved in the evolution of the magma. The magma was derived from the mantle but caused crustal assimilation and partial melting during its upward migration. The ore has the same characteristics as the granite porphyry in REE composition, and the ore-forming age in the Dongxiang copper deposit is close to the age of magma intrusion. It is shown that magmatic intrusion had an important contribution to the formation of the Dongxiang copper deposit.

关 键 词：花岗斑岩 LA-ICP-MS锆石U-PB年龄 地球化学 成因 东乡 

分 类 号：P597.3[天文地球—地球化学] P588.12[天文地球—地质学]