| 滇西鲁甸金沙江结合带新发现退变榴辉岩 |
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| 引用本文： | 王启宇,牟传龙,王保弟,贺娟,王秀平.滇西鲁甸金沙江结合带新发现退变榴辉岩[J].地球科学,2020,45(8):2978-2988. |
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| 作者姓名： | 王启宇 牟传龙 王保弟 贺娟 王秀平 |
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| 作者单位： | 1.山东科技大学地球科学与工程学院, 山东青岛 266590 |
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| 基金项目： | 中国地质调查局项目DD20160016中国地质调查局项目DD20190053 |
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| 摘 要： | 在滇西鲁甸地区金沙江结合带新发现退变榴辉岩，其在野外呈透镜体状产于石榴子石白云母石英片岩中.利用电子探针及激光拉曼分析发现石榴子石和锆石中残留绿辉石包体.石榴子石及基质中的白云母为多硅白云母(Si(p.f.u)=3.27~3.53)，指示岩石经历了高压变质作用过程.石榴子石发育进变质生长成分环带.岩相学及矿物化学特征显示，退变榴辉岩大致经历了进变质角闪岩相、峰期榴辉岩相、早期退变质以及晚期强退变这4个世代矿物组合，各阶段典型的矿物组合依次为Grt+AmpI+Qtz、Grt+Omp+Rt+Qtz+Phe、Pl+Di+AmpⅡ+Ilm+Spn+Qtz、AmpⅢ+Pl+Czo+Ilm+Qtz.该新发现对金沙江结合带复杂的变质演化P-T-t轨迹样式及年代格架、以金沙江洋为代表的整个西南三江地区古特提斯洋-陆俯冲-碰撞-造山的复杂构造演化历史以及微陆块的拼贴机制等关键科学问题的解决提供了极为重要的素材和更多的约束，具有重要的科学意义.
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| 关 键 词： | 金沙江结合带 绿辉石 岩相学 矿物化学 退变榴辉岩 滇西 鲁甸 |
| 收稿时间： | 2020-03-20 |
Discovery and Its Geological Significance of Retrograde Eclogite in Jinshajiang Suture Zone in Ludian Area of West Yunnan Province |
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| Abstract: | Retrograde eclogite was newly discovered in Jinshajiang suture zone in Ludian area of West Yunnan Province,which occurs as lenses in garnet muscovite quartz schist. The EPMA and LRS analyses reveal that there were residual omphacite inclusions in garnet and zircon. The muscovites developed in garnet and matrix are phengite(Si(p.f.u)=3.27-3.53),indicating that the rock has undergone a high pressure process of metamorphism. Garnets in this rock have preserved prograde metamorphic zonation. Petrographic and mineral chemical characteristics indicate that the retrograde eclogite has roughly undergone 4 generations of mineral assemblages including the progressive amphibolite facies mineral assemblage,the peak phase eclogite facies mineral assemblage,the early retrograde metamorphic mineral assemblage and the late strongly retrograde mineral assemblage. The typical paragenetic association of minerals of each stage is Grt+AmpI+Qtz,Grt+Omp+Rt+Qtz+Phe,Pl+Di+AmpⅡ+Ilm+Spn+Qtz,AmpⅢ+Pl+Czo+Ilm+Qtz,respectively. These new findings will provide important evidences and more restraints to the key scientific problems such as the complex P-T-t path style of metamorphic evolution and chronostratigraphic framework in Jinshajiang suture zone,the complex tectonic evolution history of Paleo-Tethys ocean of subduction,collision,orogenesis,and the collage mechanism of microcontinent and so on. It has important scientific significance. |
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