云南永胜分水岭矿区富碱斑岩地球化学、锆石U-Pb年龄及其地质意义

发布时间：2018-06-05 06:38

本文选题：富碱斑岩 + 锆石U-Pb年龄　；参考：《大地构造与成矿学》2016年03期

【摘要】：云南永胜分水岭矿区富碱斑岩体位于扬子地块西缘宾川-程海断裂与箐河断裂交汇部位,属于金沙江哀牢山富碱斑岩带组成部分,主要由黑云母花岗闪长斑岩(BGDP)和花岗闪长斑岩(GDP)组成。两类岩石均具有富碱(BGDP的K_2O+Na_2O均值为8.22%、GDP的K_2O+Na_2O均值为8.13%)、富钾(BGDP的K_2O/Na_2O均值为1.08,GDP的K_2O/Na_2O均值为1.2)和准铝质(BGDP的A/CNK均值为0.95、GDP的A/CNK均值为0.94)特征,表明二者均属准铝质高钾钙碱性系列的富碱斑岩。两类岩石均富集大离子亲石元素(Rb、Ba、Pb、Sr)、Th、U和LREE,亏损高场强元素(Ta、Nb和Ti),二者稀土元素配分模式均为右倾平滑型,且Eu异常不显著(δEu=0.85~1.12)。地球化学特征表明它们属同源岩浆演化的产物,具有相似的源区特征和成岩动力学背景。花岗闪长斑岩LA-ICP-MS锆石U-Pb年龄为34.5±0.3 Ma(MSWD=1.5,n=19),落在金沙江哀牢山富碱斑岩带岩浆活动的高峰期内(45~30 Ma)。综合岩石学、地球化学和成岩年代学资料,认为分水岭矿区富碱斑岩形成的动力学条件和源区特征与金沙江哀牢山富碱斑岩带一致,即形成于印度欧亚板块碰撞期后动力学性质转换背景下,是加厚下地壳和上地幔部分熔融的产物,与金沙江哀牢山走滑断裂构造活动密切相关。
[Abstract]:The alkali-rich porphyry rock body of Yongsheng Fenshuiling mining area in Yunnan Province is located at the junction of Binchuan-Chenghai fault and Qinghe fault in the western margin of the Yangtze block and is a part of the alkali rich porphyry belt of the Jinshajiang River and the Ailaoshan area. It is mainly composed of biotite granodiorite porphyry (BGDP) and granodiorite porphyry (GDP). The two types of rocks are characterized by K _ 2O Na_2O mean value of alkali-rich Na_2O and K _ 2O Na_2O mean value of 8.13, K _ 2O Na_2O mean value of 1.08 Na_2O and A/CNK mean value of A/CNK of 0.95% ~ 0.94%, respectively, which are characterized by K _ 2O Na_2O mean value of K _ 2O Na_2O and K _ 2O Na_2O mean value of K _ 2O Na_2O of K _ 2O _ rich rock, and K _ 2O Na_2O mean value of K _ 2O Na_2O is 1.08%. The results show that both of them belong to the alkali rich porphyry of high potassium calc-alkaline series. The two types of rocks are homogeneous rich in large ion lithophile elements RbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbBPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPbPb@@ The geochemical characteristics indicate that they belong to the product of homologous magma evolution and have similar source characteristics and diagenetic dynamic background. The LA-ICP-MS zircon U-Pb age of granodiorite porphyry is 34.5 卤0.3MaMMSWD1. 5 ~ 1. 5 ~ 1. 5 ~ 1. 5 and falls during the peak period of magmatic activity in the Ailaoshan alkali-rich porphyry belt, Jinsha River. Based on the petrological, geochemical and diagenetic chronological data, it is considered that the dynamic conditions and source characteristics of alkali-rich porphyry in the Dianshuiling mining area are consistent with the alkali-rich porphyry belt on the Jinshajiang River. It was formed in the background of dynamic property transformation in the post-collision period of the Indian and Eurasian plates and is the product of partial melting of the thickened lower crust and upper mantle, which is closely related to the strike-slip tectonic activity of the Ailaoshan, Jinshajiang River.
【作者单位】：昆明理工大学国土资源工程学院;云南省有色地质局地质勘查院;云南省有色地质局;中国科学院地球化学研究所矿床地球化学国家重点实验室;
【基金】：中国地质调查局项目(1212011120607) 云南省有色地质局项目(2013100001)联合资助
【分类号】：P597.3;P588.13;P612

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