Structural, Paleomagnetic and Sedimentary Evidences for Mesozoic Rotation of the Sichuan Basin
The Yangtze block, which centers on the Sichuan basin, is one of the main tectonic elements of China, and its tectonic evolution history is largely different from other tectonic elements: its has long been dominated by sedimentation from the Sinian to the Mesozoic, except in early Late Permian time, in which a large mass of basaltic magma erupted within the southwestern part of the block, but it was actually only temporary. By the time of the Cenozoic, mere generally had occurred large-scale sedimentation within the other tectonic elements of China, but the sedimentation within the Yangtze block had actually stopped, and its tectonic origin is worth discussing, especially with regard to unveiling the process of oil-gas resources generation, storage and coverage in the Sichuan basin and its adjacent areas, the research value is all the more significant. The paleomagnetic result unveils that, collision between the Yangtze and North China blocks along the Qinling-Dabie erogenic belt occurred in the Late Paleozoic and persisted to the Triassic. After the collision, the Yangtze block immediately rotated clockwise relative to the North China block with a rotating degree of 67°Notwithstanding, whether the rotation is rigid or plastic, what is the associated deformation, and whether the rotation was stilling going on after this collision? These series of questions are still unknown. In view of these, in undertaking the project of SINOPEC (the Continental Tectonics of the Middle and Upper Yangtze Block in South China and Prospect of the Marine-Fades Oil-Gas Resources), we have carried out the structure, the paleomagnetism and the sedimentation research. The paleomagnetic result obtained from the northern part of the Sichuan basin shows that: during the Triassic, the Sichuan basin (reference point) was in the low attitude area of the Northern Hemisphere (8.1±1.7°; during the Triassic, Sichuan basin quickly moved northward by 9.9°(about 1 000 km), with an average traveling speed about 3.8 cm/a. After the Triassic, the basin moved slowly to the north with an average speed of 1.5 cm/a. During the Early Triassic and the Early Cretaceous,while moving northwards, Sichuan basin was also continually rotating clockwise, with a total rotation degree of 33.7° with an average rotating rate of 0.3°Ma. After the Late Triassic, Sichuan basin had reduced its speed of northward movement, possibly due to obstruction of North China block along the Qinlin erogenic belt.
structure paleomagnetism sedimentation,Mesozoic rotation of the Sichuan basin.
Wang Erchie Zhang Guowei Yin Jiyun Wang Gang Fan Chun
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;Department o Department of Geology, Northwest University, Xian 710069, China Geological Institute of Yunnan, Kunming 650051, China Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
国际会议
The IPACES 6th Annual Meeting(“现代地球科学，交流与合作国际学术研讨会暨第六届IPACES学术年会)
武汉
英文
550
2007-04-25（万方平台首次上网日期，不代表论文的发表时间）