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| 青藏高原新生代形成演化的整合模型——来自火成岩的约束 | |
| 引用本文： | 罗照华,莫宣学,侯增谦,邓万明,王江海,赵志丹,喻学惠,李建平.青藏高原新生代形成演化的整合模型——来自火成岩的约束[J].地学前缘,2006,13(4):196-211. |
| 作者姓名： | 罗照华 莫宣学 侯增谦 邓万明 王江海 赵志丹 喻学惠 李建平 |
| 作者单位： | 1. 中国地质大学,地质过程与矿产资源国家重点实验室,北京,100083 2. 中国地质科学院,地质研究所,北京,100037 3. 中国科学院,地质与地球物理研究所,北京,100029 4. 中国科学院,广州地球化学研究所,广东,广州,510640 |
| 基金项目： | 国家研究发展基金;国家高技术研究发展计划(863计划) |
| 摘 要： | 深部过程是青藏高原演化的主导因素,其他地质过程都可以看作是对深部过程的响应。因此,一个构造旋回(阶段)的地球动力学事件链可以概括为深部地质过程—幔源岩浆活动—壳源岩浆活动—陆壳增厚—地表隆升—表层剥蚀与沉积,其中幔源岩浆活动的研究成为追索青藏高原演化历史的关键环节。据此,青藏高原演化的关键性时间坐标为80、45、27、17、9和4Ma。青藏高原新生代火成岩具有三种展布形式:与雅鲁藏布缝合带平行的岩浆带、沿深大断裂展布的岩浆带和藏北离散性岩浆分布区,它们分别受控于大陆碰撞、大规模走滑和岩石圈拆沉构造体制,且都受控于印度—亚洲软流圈汇聚过程。据此,文中提出了一个描述青藏高原演化的整合模型:南北向地幔对流汇聚控制了岩石圈块体的相对运动,并最终导致印度—亚洲大陆的碰撞和沿碰撞带的大规模岩浆活动;碰撞之初(白垩纪末期),大陆岩石圈块体的刚性属性有利于应力的远程传递和块体旋转,沿块体边界分布的大型走滑断裂控制了岩浆活动的发生;随着挤压过程的持续进行,岩石圈块体的受热和变形,高原岩石圈的重力不稳定性增加,最终导致拆沉作用和软流圈物质的大规模上涌以及藏北高原的离散性岩浆活动。在高原演化中,岩石圈拆沉作用具有重要意义,许多地质事件的发生都与此有关。同时,软流圈的汇聚还导致软流圈物质的向东挤出,并因此造成青藏高原岩石圈的向东挤出和晚新生代的伸展构造。 |
| 关 键 词： | 青藏高原 深部过程 岩浆活动 构造体制 大陆动力学 整合模型 事件链 |
| 文章编号： | 1005-2321（2006）04-0196-16 |
| 收稿时间： | 2006-04-13 |
| 修稿时间： | 2006年4月13日 |
An integrated model for the Cenozoic evolution of the Tibetan plateau: constraints from igneous rocks |
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| LUO Zhao-hua,MO Xuan-xue,HOU Zeng-qian,DENG Wan-ming,WANG Jiang-hai,ZHAO Zhi-dan,YU Xue-hui,LI Jian-ping.An integrated model for the Cenozoic evolution of the Tibetan plateau: constraints from igneous rocks[J].Earth Science Frontiers,2006,13(4):196-211. | |
| Authors: | LUO Zhao-hua MO Xuan-xue HOU Zeng-qian DENG Wan-ming WANG Jiang-hai ZHAO Zhi-dan YU Xue-hui LI Jian-ping |
| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences , Beijing 100083 ,China;2. Institute of Mineral Resources, CAGS, Beijing 100037, China;3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 ,China;4. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China |
| Abstract: | The prominent factors controlling the Cenozoic evolution of the Tibetan plateau are the Earth's deep processes, other geological processes can be considered as secondary responses of varying levels of importance. Therefore, a geodynamic event chain in the current tectonic cycle can be summarized as a deep process mantle-derived magmatism ,crust-derived magmatism, crustal thickening,surface raising,erosion,and sedimentation. Respectively, the key time scale for this Cenozoic evolution of the Tibetan plateau is 80 Ma, 45 Ma, 27 Ma, 17 Ma, 9 Ma and 4 Ma. The Cenozoic igneous rocks of the Tibetan plateau show three types of arrangement: magmatic belts parallel to the Indus-Yarlung-Zangbo suture, magmatic belts along large strike-slip faults, and the distributed igneous field in northern Tibet. They are controlled tectonically by continental collision, large scale strike-slip faulting and lithospheric delamination,respectively. All three tectonic expressions are driven by Indian-Asian asthenospheric convergence. An integrated model based on this is described in this paper. The north to south mantle convergence drove the opposite movement of the lithospheric blocks, and, finally, induced the collision of the Indian and Asian continents and the large scale of magmatism along the suture. At the late Cretaceous preliminary stage, the rigid features of the continental lithosphere blocks contributed to long-distance propagation of collision stress and to block rotation; magmatism occurred along the large-scale faults. With continuous compression, heating, and deformation of the lithosphere blocks, the gravitational instability of the Tibetan lithosphere increased and finally led to lithosphere delamination, large scale asthenosphere upwelling and distributed magmatism in the northern Tibet. In the evolution of the Tibetan plateau, lithosphere delamination is an important process, which influenced to many other geological events. At the same time, asthenospheric convergence also led to eastward asthenospheric extrusion. The later induced eastward lithospheric extrusion and the late Cenozoic extension of the Tibetan plateau. |
| Keywords: | Tibetan plateau deep process magmatism tectonic regime continental dynamics integratedmodel event chain |
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