华北克拉通北部迁安紫苏花岗岩LA-ICP-MS锆石U-Pb定年、地球化学及地质意义

发布时间：2018-01-07 13:36

本文关键词：华北克拉通北部迁安紫苏花岗岩LA-ICP-MS锆石U-Pb定年、地球化学及地质意义　出处：《岩石学报》2016年09期 　论文类型：期刊论文

【摘要】：紫苏花岗岩是太古宙高级变质地体的主要物质组成,对其开展岩石成因与年代学研究,可深入理解早期大陆生长及其机制。本文以迁安紫苏花岗岩为窗口,探讨其成因与机制,通过精确的LA-ICP-MS锆石U-Pb测年获得其成岩年龄为2544±22Ma,指示了新太古代晚期的一次岩浆活动。岩石变质年龄为2475±87Ma,证明随后的高级变质作用年龄范围为2439~2501Ma。岩石地球化学研究表明:迁安紫苏花岗岩SiO_2=59.14%~66.97%,MgO=1.62%~3.12%,富Ba(574×10-6~1572×10-6),LREE((La/Yb)N=22.3~79.0),亏损HFSE,不存在Eu负异常(δEu=1.76~3.43),其高Sr/Y值(85~179)与(La/Yb)N值指示了与TTG的相关性。结合样品地球化学特征及锆石U-Pb年龄分析,并与本区域大地构造背景相结合,迁安紫苏花岗岩可能是角闪岩相条件下偏中性含水玄武质原岩高温部分熔融的产物,应当形成于地幔柱背景。
[Abstract]:Perilla granites are the main material composition of the Archean high grade metamorphic terrane. The petrogenesis and chronology of the granites can be studied in depth to understand the early continental growth and its mechanism. In this paper, Qianan perilla granites are taken as the window. Its genesis and mechanism are discussed, and its diagenetic age is 2544 卤22Ma by accurate LA-ICP-MS zircon U-Pb dating. It indicates a magmatic activity in the late NeoArchaean. The metamorphic age of the rocks is 2475 卤87Ma. It is proved that the later advanced metamorphic age ranges from 2439 to 2501 Ma. The petrogeochemical study shows that the SiO2J _ 2J _ 2O _ 2P _ 2O _ 2P _ 2O _ 2 is 66.97% in Qianan porphyry granite. Ba(574 脳 10-6, 1572 脳 10-6, LREEN, La- / Yb ~ (2) N ~ (22. 3) ~ (79. 0). There is no negative EU anomaly (未 EU ~ (1. 76) ~ (3.43)). Its high Sr/Y value (85 / 179) and La / P / YbN value indicate the correlation with TTG, combined with the geochemical characteristics of the sample and zircon U-Pb age analysis. Combined with the regional tectonic setting Qianan perilla granitoids may be the product of high temperature partial melting of neutral water-bearing Black Tortoise prorocks under amphibolite facies and should be formed in the mantle plume setting.
【作者单位】：中国地质大学地质过程与矿产资源国家重点实验室;河南省地质矿产勘查开发局第二地质勘查院;
【基金】：国家重点基础研究发展计划“973”项目(2012CB416806) 中国地质调查局项目(12120114026901)联合资助
【分类号】：P588.121;P597.3
【正文快照】： 1.中国地质大学地质过程与矿产资源国家重点实验室,北京1000832.河南省地质矿产勘查开发局第二地质勘查院,郑州4500001.State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China2.No.2 Geo-exploration In

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