| 青藏高原狮泉河-拉果错-永珠-嘉黎蛇绿混杂岩带时空结构与构造演化 |
| |
| 引用本文： | 王保弟,刘函,王立全,贺娟,王冬兵,李奋其,吴喆.青藏高原狮泉河-拉果错-永珠-嘉黎蛇绿混杂岩带时空结构与构造演化[J].地球科学,2020,45(8):2764-2784. |
| |
| 作者姓名： | 王保弟 刘函 王立全 贺娟 王冬兵 李奋其 吴喆 |
| |
| 作者单位： | 1.中国地质调查局成都地质调查中心, 四川成都 610081 |
| |
| 基金项目： | 中国地质调查局项目DD20190053国家自然科学基金项目41773026 |
| |
| 摘 要： | 青藏高原中部狮泉河-拉果错-永珠-嘉黎蛇绿混杂岩带（简称SYMZ）位于班公湖-怒江缝合带与雅鲁藏布江缝合带之间，其构造属性存在很大争议，制约了对青藏高原多岛弧盆系构造演化的理解.根据新的地质调查资料、研究成果并结合分析数据，系统总结了该蛇绿混杂岩带的地质特征，讨论了其构造演化过程.一系列新资料及新认识表明SYMZ是分割北拉萨地块和中拉萨地块的一条独立的蛇绿混杂岩带，是特提斯构造域多岛弧盆系的组成部分.在狮泉河、拉果错、阿索、永珠、凯蒙等地发育比较典型的蛇绿岩组合，高精度年代学数据指示洋盆主体发育于178~160 Ma，比班公湖-怒江洋盆主体发育时限（188~162 Ma）要晚10 Ma左右，阿索一带蛇绿岩残片记录洋盆一直持续到113 Ma.SYMZ侏罗纪基性岩具有MORB型（洋中脊玄武岩）和IAT型（岛弧拉斑玄武岩）火山岩的地球化学性质，属于洋内弧型和洋中脊型蛇绿混杂岩；早白垩世基性岩具MORB和火山弧玄武岩的双重特性，指示其很可能形成于SSZ的构造环境，不同于同时期班公湖-怒江特提斯受地幔柱热点影响的洋盆性质.同时，在拉果错、永珠、凯蒙等地区识别出侏罗纪前弧玻安岩及玻玄岩系列，一致指示SYMZ洋壳发生过洋内俯冲.在此基础上，结合区域地质资料，构建了SYMZ特提斯洋的时空格架及构造演化历史，认为经历了晚三叠世-早侏罗世洋盆裂解-扩张、中-晚侏罗世洋内俯冲、早白垩世俯冲消减和早白垩世末期洋盆消亡四个阶段，为特提斯洋的构造演化及大地构造过程再造提供了重要的地质学证据.
|
| 关 键 词： | 狮泉河-拉果错-永珠-嘉黎蛇绿混杂岩带 班公湖-怒江缝合带 洋内俯冲 SSZ型蛇绿岩 特提斯 构造演化 青藏高原 构造地质学 |
| 收稿时间： | 2020-03-25 |
Spatial-Temporal Framework of Shiquanhe-Laguoco-Yongzhu-Jiali Ophiolite Mélange Zone,Qinghai-Tibet Plateau and Its Tectonic Evolution |
| |
| Abstract: | The Shiquanhe-Laguoco-Yongzhu-Jiali ophiolite mélange zone (SYMZ) is located between the Bangongco-Nujiang suture zone and the Yarlung-Zangbo suture zone in the central Qinghai-Tibet Plateau. The tectonic property of the SYMZ remains controversial, which restricts the application of archipelagic arc-basin system theory to the evolution of Qinghai-Tibet Plateau. Based on recent geological survey information, research results and comprehensive data analyses, in this paper, it summarizes the geological feature and discusses the tectonic process of the SYMZ. The SYMZ represents an independent ophiolitic mélange zone dividing the north Lhasa Terrane and central Lhasa Terrane, which is part of the Tethyan archipelagic arc-basin system. The typical ophiolite mélange suites are distributed in such places as Shiquanhe, Laguoco, Aso, Yongzhu and Kaimeng, and high precision geochronology data show that the main ocean basin was formed during 178-160 Ma, which was about 10 Ma later than the formation of the Bangongco-Nujiang ocean basin (188-162 Ma). The Aso ophiolitic mélange reflects that the SYMZ ocean basin had existed until 113 Ma. The Jurassic mafic rocks of the SYMZ show the geochemistry characteristics of MORB and IAT, belonging to the Oceanic Arc and MORB type ophiolites. The Early Cretaceous mafic rocks show both MORB and arc basalt characters, suggesting they probably formed in the tectonic setting of SSZ, different from the contemporaneous Bangongco-Nujiang ocean which was influenced by the mantle plume. The Jurassic boninites and bonibasalts series places like Laguoco, Yongzhu and Kaimeng were found in this study, indicating the intra-oceanic subduction of the SYMZ oceanic slab. Combined all these new discoveries with regional geological data, the spatial-temporal framework of the SYMZ Tethyan Ocean and its tectonic evolution history are established. The SYMZ Tethyan Ocean opened and spread in Late Triassic-Early Jurassic, the intra-oceanic subduction lasted during Middle-Late Jurassic, oceanic slab subduction begun in the Early Cretaceous, and finally ocean basin was extinct in the late Early Cretaceous. This study provides important geological evidences for understanding the lithosphere evolution and tectonic process of the Tethyan. |
| |
| Keywords: | |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
| 点击此处可从《地球科学》下载免费的PDF全文 |
|
