| 青藏高原造山带的某些特征 |
| |
| 关键词:the Qinghai-Tibet plateau oregenic belts rigid basement soft basement rejuvenate orogenic belt paleo-Western-domains platform |
| 基金项目: |
|
| 摘要点击次数: 1994 |
| 全文下载次数: 2196 |
| 摘要: |
| Some Characteristics of Orogenic Belts in the Qinghai-Tibet Plateau |
| There are many orogenic belts developed in the Qinghai-tibet plateau.Various information on the whole process of formation and evolution of the Qinghai-Tibet plateau lithosphere is preserved in them. 1.Orogenic belts in the morthern rigid basement crust Someregions of Qinghai,Gansu and Xinjing,north of the central Kunlun fault,were partly consolidated during early Proterozoic and were fully consolidated in middle Proterozoic,and then became relatively stable tectonic units.Becase of the long evolution of their crystallized basemet and their high consolidation,they demonstrated rigidity.The Qilianshan,Altun Mts northern Qaidam,and northern Kunlun(even northern West Qinling)are just the orogenic belts developed from the break-up of these rigid blocks.The rift of the rigid blocks started at the beginning of Paleozoic or slightly earlier.The rifting continued and ocean basins emerged afterward.the ocean basins shrank and had been folded by the end of Silurian. 2. Orogenic belts in southern soft basements In Hoh Xil-Bayan Xar and Tangula regions,south of the central Kunlun fault ,the metamorphic basement below the oregenic belts are generally regarded as westward extension of the basement of the Yangtze platform,but softer than Yangtze basement as a whole.There are some small blocks,e.g.,songpan block,Shuiluohe-Zhongza block and Qamdo-simao block.Like those rigid parts of Yangtze platform,farther southward,in the lake area of northern Tibet and Himalayas area the basement rocks were consolidated in 500-600Ma(Pan-African age ).They have medium grade metamorphism and crystallization,yunger history.Orogenic belts in soft basement crust have features as follows:1) More active,they experience complex polycyclic opening-closing.2)During the pre-orogeny rifting stage,extended huge ocean basins,their continental margins and sea-mount sedimentary environment came out,and assembly of block accompaniened trench-are systems and terrane accretions.3) Post-orogeny deformation was comple.Besides simple thrusting,nappe and detachment strutures were also developed.A large amount of strike slipping achieved due to rotation of rigid blocks between them. 3.Notable thickening of the crust of Qinghai-Tibet plateau and unlifting of the Plateauin late Pliocene The orogenic blets in the northern rigid blocks show simple compression in bothe southward and northward directions.The huge nountains thrusted toward the adjacent basins (rigid frament) in opposite directions which forms fan symmetric patterns and rejuvenate the orogenic belt.The orogenic belts in the southern soft crust demonstrated motable strike slip faulting beside compression in north-south direction.In view of this,the characteristics of the orogenic belts are controlled by the nature of the crustal basement and have distinct inheritance. |
| CHEN Bing-wei,WANG Yan-bin.1994.Some Characteristics of Orogenic Belts in the Qinghai-Tibet Plateau[J].Acta Geoscientica Sinica,15(3,4):45-53. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|