| 关于雅鲁藏布江缝合带(东段)的新认识 |
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| 引用本文： | 郝杰,柴育成.关于雅鲁藏布江缝合带(东段)的新认识[J].地质科学,1995,30(4):423-431. |
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| 作者姓名： | 郝杰 柴育成 |
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| 作者单位： | 中国科学院地质研究所 北京 100029 |
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| 基金项目： | 中国科学院地质研究所所长基金 |
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| 摘 要： | 国内外不少地质学家大都将雅鲁藏布江蛇绿岩带视为印度板块与亚洲板块之间的缝合带。但是,笔者等在喜玛拉雅造山带的东段即仁布-康马一线以东地区的研究却发现,在雅鲁藏布江蛇绿岩带的南侧发育着一个宽大的增生杂岩体,它与雅江蛇绿岩是同一大洋即特提斯喜玛拉雅洋俯冲消减的产物,前者代表着特提斯喜玛拉雅洋消亡遗迹的主体,是印度板块与拉萨地块之间缝合带的主要组成部分;而后者代表的是俯冲带与拉萨地块之间的残余洋壳,它由北向南仰冲,构成日喀则-桑日弧前盆地前缘脊和南部基底,因而其不代表主缝合带。北喜玛拉雅增生杂岩体的发现改变了以Gansser(1964)为代表提出的喜玛拉雅造山带的构造模式,为重新审视印度板块与拉萨地块缝合作用过程提供了一个重要的地质制约和新的研究途径。
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| 关 键 词： | 雅鲁藏布江 缝合带 蛇绿岩 北喜玛拉雅 增生杂岩体 新认识 |
| 收稿时间： | 1994-11-02 |
| 修稿时间： | 1994-11-02; |
NEW UNDERSTANDINGS TO THE YARLUNG-ZANGBO SUTURE ZONE (EASTERN PART), SOUTH TIBET |
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| Hao Jie ,Chai Yucheng, Li Jiliang.NEW UNDERSTANDINGS TO THE YARLUNG-ZANGBO SUTURE ZONE (EASTERN PART), SOUTH TIBET[J].Chinese Journal of Geology,1995,30(4):423-431. |
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| Authors: | Hao Jie Chai Yucheng Li Jiliang |
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| Institution: | Institute of Geology, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | Yarlung-Zangbo Ophiolite Zone (YZOZ) is classically believed to be YarlungZangbo Suture Zone (YZSZ) between indian and Asian Plates, and Triassic-Cretaceous flysch in Tethys Himalayan Zone which lies just south of the YZOZ is taken as a sedimentary sequence deposited on the northern passive margin of the Indian Plate. During the Investigation in the east aside of Renbu-Kangma, we have found a large number of the basic ultrabasic rocks which were as “no foot” wrapped in the “flysch” and I-type granite-granodiorites which intruded in the “flysch", as well as radiolarian chert and basalt beds in the “flysch"; thus we suggest that the “flysh"developed in Tethys Himalayan Zone virtually constituted an accretionary complex called as N-Himalayan Accretionary Complex (NHAC) in this paper, and the NHAC and the YZOZ were all the remains of a same oceanic crust called as Tethys-Himalayan Ocean (THO). The former was attributed to the northward subduction of the THO and represents the main part of the Suture zone; while the latter one only represents a southward obducting remnant oceanic crust between the subduction zone and Lhasa Terrain, and constituted the southern basement and fore-ridge of the Xigaze-Sangri Fore-arc Basin. Based on the new discovery we point out that the THO was possibly formed during Middle or Early Triassic and was well developed in Jurassic. At the end of Late Jurassic, the THO began to subducting northward. The first subduction zone occurred within the oceanic crust, and the zone just along the south side of the YZOZ. The oceanic crust represented by the YZOZ between the subduction zone and Lhasa Terrain southward obducted to constitute the south part of basement and the fore-ridge of Xigatze-Sangri Fore-arc Basin. In the south side of the ridge the NHAC was developed. With southward growing of the NHAC, the subduction zone southward retrogressed, and the volcanic-magmatic arc on the middle part of Lhasa Terrain during the late Jurassic and Early Cretaceous southward migrated also into Gangdise Zone in the south part of Lhasa Terrain during Late Cretaceous and Paleocene. In Eocene the magmatic arc further migrated southward into the NHAC. By the end of Eocene or Early Oligocene the THO vanished fully and the collision between indian Plate and the NHAC began Terrain. The NHAC overthrusted onto the northern passive margin of Indian Plate to make the continuous sedimentary sequence from Paleozoic to Eocene Period on the margin involved into the foreland zone. |
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| Keywords: | Yarlung-Zangbo Suture zone Ophiolite Northern Himalayas Accretionary Complex New Understanding |
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