可可西里—巴颜喀拉三叠纪沉积盆地的形成及演化

【作者】 朱迎堂；

【导师】 伊海生；

【作者基本信息】 成都理工大学 ， 矿物学岩石学矿床学， 2006， 博士

【摘要】 可可西里—巴颜喀拉三叠纪沉积盆地，位于青藏高原腹地北东部。构造范围北以木孜塔格—东昆南—阿尼玛卿断裂带，南以西金乌兰—玉树—金沙江断裂带，东以龙门山推覆构造围限的巨型倒三角形区域，面积愈70×10~4km~2，盆地中的沉积物主要是三叠纪浊积岩系，最厚达10×10~3m。由于其特殊的大地构造位置和复杂的成因，长期以来成为青藏高原大地构造和特提斯研究的热点地区和关键地区。因受高寒缺氧、气候恶劣、交通极差等诸多困难的影响，研究程度非常低，地质上号称“百慕大三角”。可可西里—巴颜喀拉地区不仅有丰富的矿产资源，而且是江河源区，青藏公路及铁路横穿该盆地西段可可西里地区，国家“三江源”自然保护区、可可西里自然保护区及南水北调西线工程部署在这里，因此研究可可西里—巴颜喀拉三叠纪沉积盆地具有重要的理论价值和现实意义。 前人的研究工作主要限于地质构造、区域地层、古生物和地球物理等方面。作者历经十个春秋的野外填图和科学考察，获得了丰富而又翔实的第一手基础资料。论文将可可西里—巴颜喀拉三叠纪沉积盆地的形成演化置于冈瓦纳大陆的裂解、古特提斯域的全球构造框架中，以活动论、板块构造为理论指导，从沉积相、古水流、物源区、深海放射虫硅质岩及与盆地有关的岩浆作用，如基性岩墙群、蛇绿岩、俯冲弧火山岩等方面的综合研究，认为是一个典型的残留洋盆，并反演了可可西里—巴颜喀拉沉积盆地形成及演化过程。 可可西里—巴颜喀拉沉积盆地自北而南包括木孜塔格—昆仑—阿尼玛卿构造带、西秦岭构造带、可可西里—巴颜喀拉构造区、西金乌兰—玉树—金沙江构造带，各构造区带内的岩石地层及其分布、地层层序各具特色，反映了沉积盆地中不同背景、不同时期地层的分布及充填规律。可可西里—巴颜喀拉主构造区发育二叠纪—三叠纪地层，二叠纪与三叠纪地层为连续沉积关系，而且均为大陆斜坡—深海洋盆沉积，发育浊积岩系。盆地边缘受俯冲增生控制作用，发育有石炭—中三叠世放射虫硅质岩、岩崩、滑塌和碎屑流沉积，具有从盆地边缘到内部依次发育蛇绿混杂岩—混杂堆积—浊积岩—深海盆地的演化规律，这种增生混杂沉积与盆内浊积岩系之间并没有截然的时间和空间发育差异，而是相互依存。 在可可西里—巴颜喀拉盆地的中西部饮马湖、巴颜喀拉山扎朵等地发现三叠纪地层最高层位，其中发育有浅海陆棚—海陆交互相风暴岩、潮汐层理及夹煤线沉积，采集到以膨凸厚壳的Myophori(Costatoria)mansuyi和Placunopsis remuensis属为代表的滨海相双壳类动物群组合，其中Myophoria(Costatoria) mansuyi，Myophoria(Elegantinia) venusta，Placunopsis remuensis常见于诺利期或晚三叠世地层，更多还原

【Abstract】 The Hoh Xil-Bayan Har Triassic sedimentary basin, which is located in the northeast of Qinghai-Tibet Plateau hinderland, is tectonically bounded by Muztag-South of eastern Kunlun- A’nyemaqen in the north, by Xijir Ulan-Yushu-Jinsha River fault zone in the south, and by Longmenshan nappe structure zone in the east. It’s shape likes a huge inverted delta with an area of over 70 sq. kilometers. Sediments in the basin primarily belong to the Triassic turbidite, up to 10×10~3meters in thickness. Because of Hoh Xil-Bayan Har’s special geotectonical position and complex genesis, it has been a hotspot and key area in studying Qinghai-Tibet Plateau geotectonics and Tethys. On account of alpine hypoxia, bad weather , poor traffic and other many difficulties as well as low degree in studying, the region is geologically called "Bermuda Triangle". The Hoh Xil-Bayan Har area not only is rich in mineral resources, but also is a birthplace from which many rivers come. And the Qinghai-Tibet highway and railway cross the Hoh Xil in the western region of the basin , Sanjiangyuan nature reserve, Hoh Xil nature reserve and the western route water transfers project from south to north are situated here. So the research on Hoh Xil-Bayan Har Triassic sedimentary basin has important theoretical value and practical significance.Previous studies are mostly restricted to geological tectonics, regional stratigraphy, paleontology and geophysics, etc. The writer has acquired many detailed firsthand basic information by field geological mapping and scientific expedition for a decade.By the formation and evolution of Hoh Xil-Bayan Har Triassic sedimentary basin under the global tectonic framework of Gondwandland split and paleotethys domain, through the theoretical guide on activity and plate tectonics, and research on sedimentary features, paleocurrent, provenance, abyssal radiolarian cherts and magmatism related to the basin, such as basic dyke swarm, ophiolite and subduction arc volcanics, etc. It has been considered a typical remnant ocean basin, moreover, the process of formation and evolution of Hoh Xil-Bayan Har sedimentary basin has been demonstrated.The tectonic realm of Hoh Xil-Bayan Har sedimentary basin includes Muztag- Kunlun-A’nyemaqen tectonic zone, Western Qinling tectonic zone, Hoh Xil-Bayan Har tectonic province and Xijir Ulan-Yushu- Jinsha River tectonic zone from the north to the south, in which the distribution of lithostratigraphy and the characteristics of stratigraphic sequence reflect the filling and distributional laws of strata in the sedimentary basin in different settings and times.The Carboniferous-Middle Permian accretion zone melange abound in Muztag- Kunlun-A’nyemaqen tectonic zone in the southern edge of basin, including ophiolite and abyssal radiolarian cherts association. The Hoh Xil-Bayan Har main tectonic region abound with the更多还原