赣中乐安加里东期花岗岩体岩石学及主、微量元素特征

发布时间：2018-09-10 20:08

【摘要】：为探讨乐安岩体的岩石类型、岩浆来源和成岩构造环境,对其开展了岩石学及主、微量元素分析研究。结果表明,乐安岩体由乐安单元、太平单元和王元单元构成岩石序列,其岩石具片麻状构造、似斑状结构,塑性变形明显,常见微粒交生体、镁铁质包体和同深成岩墙;其SiO_2含量变化大,弱过铝质,属高钾钙碱性-钾玄岩系列,稀土元素含量高,稀土配分曲线右陡倾,轻重稀土分馏明显,Eu中等负异常,富集Rb、Th、U、Ce、Nd等大离子亲石元素,相对亏损P、Sr、Ba,属低Sr、高Y、高Ba花岗岩类。研究认为,乐安岩体属壳源或S型花岗岩,主要来源于砂屑质源区,但有明显的幔源岩浆混入,其形成于后碰撞局部挤压构造环境,经历了黑云母脱水熔融作用。
[Abstract]:In order to study the rock type, magma origin and diagenetic tectonic environment of Lean rock body, petrology and analysis of main and trace elements were carried out. The results show that the Lean rock body is composed of Lean unit, Taiping unit and Wang Yuan unit. The rock has a lamellar structure, porphyry like structure, obvious plastic deformation, common particle intersection, magnesia-iron inclusion and syn-deep diagenetic wall. Its SiO_2 content changes greatly and weakly peraluminous, it belongs to the series of high-potassium calc-alkaline kaliacite, with high content of rare earth elements, right steep deviation of rare earth partition curve, obvious moderate negative anomaly of EU in fractionation of light and heavy rare earths, and enrichment of Rb,Th,U,Ce,Nd and other large ion lithophile elements. It is a low Sr, high Y and high Ba granitic type. It is considered that the Lean rock body belongs to crust source or S-type granite, mainly originated from sandy source area, but there is obvious mantle magma mixed in, which formed in the post-collision local compressional tectonic environment and experienced biotite dehydration and melting.
【作者单位】：东华理工大学地质调查研究院;江西省数字国土重点实验室;中国人民武装警察部队黄金第十支队;中国地质大学(北京);
【基金】：中国地质调查局地质调查项目(1212011120836,1212011220248)
【分类号】：P588.121

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