山东省微山稀土矿正长岩类锆石U-Pb年代学及地球化学特征研究

发布时间：2018-06-20 00:32

本文选题：鲁西地块 + 微山稀土矿　；参考：《北京大学学报(自然科学版)》2017年04期

【摘要】：为了加深对微山稀土矿碱性杂岩体岩浆活动期次及与成矿关系的理解,对微山稀土矿床碱性杂岩体进行岩相学、地球化学分析和锆石U-Pb年代学测定。结果表明,微山稀土矿碱性杂岩体正长岩类地球化学特征相似,具有同源性,为偏铝质碱性岩。稀土总量高,轻重稀土元素分馏明显,呈轻稀土高度富集模式。微量元素组成具有幔源岩浆岩的特征,富集Rb,Ba,Sr等大离子亲石元素,亏损Nb,Ta,Zr等高场强元素,Eu异常不显著。利用LA-ICP-MS U-Pb年代学方法,测得含矿石英正长岩、霓辉石英正长岩锆石U-Pb年龄分别为122.4±2.0 Ma(MSWD=5.2)和130.1±1.4 Ma(MSWD=9),存在2536±6.1 Ma(MSWD=1.6)的继承锆石,表明地壳物质参与成岩过程。结合鲁西燕山期构造演化过程,认为微山正长岩类形成于华北克拉通中生代构造体制转折后的伸展背景下,成矿作用与碱性杂岩体的演化有关。
[Abstract]:In order to better understand the magmatic activity stage of the alkaline complex of the Weishan rare earth ore deposit and its relationship with the mineralization, the lithofacies, geochemical analysis and zircon U-Pb geochronology of the alkaline complex of the Weishan rare earth deposit were carried out. The results show that the syenite of the alkaline complex of the Weishan rare earth ore deposit is of similar geochemical characteristics and homology and belongs to the metamorphic alkaline rock. The total amount of rare earth is high and the fractionation of light rare earth elements is obvious, which shows the pattern of high enrichment of light rare earth elements. The composition of trace elements is characterized by mantle magmatic rocks, rich in large ion lithophile elements, such as RB, Bai, Sr, and depleted in the anomaly of EU in high field strength elements, such as NbPU, Tahl, Zr, etc. Using LA-ICP-MS U-Pb dating method, the zircon U-Pb ages of ore-bearing syenite and aegirite quartz syenite are 122.4 卤2.0 Ma-MSWD-2) and 130.1 卤1.4 Ma-MSWDU _ (9), respectively, with the existence of 2536 卤6.1 Ma MSWD1.6), indicating that the crustal material is involved in the diagenesis process. Combined with the Yanshanian tectonic evolution process in western Shandong, it is considered that the microcalcareous syenite was formed in the extensional setting after the transition of the Mesozoic tectonic system of the North China Craton, and the mineralization is related to the evolution of the alkaline complex.
【作者单位】：造山带与地壳演化教育部重点实验室北京大学地球与空间科学学院;山东省地质矿产勘查开发局;山东省鲁南地质工程勘察院;
【基金】：山东省地质矿产勘查开发局地质科技攻关项目(KY201408)资助
【分类号】：P597.3;P618.7

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