In the last decade, deep seismic sounding (DSS) of profiles several ten thousand kilometers in length has beenconducted in the mainland of China. A lot of results published in Chinese were compiled and a map of Mohode...In the last decade, deep seismic sounding (DSS) of profiles several ten thousand kilometers in length has beenconducted in the mainland of China. A lot of results published in Chinese were compiled and a map of Mohodepth was presented in this paper. Coverage of DSS profile is not uniform,and is lacking in some areas, especiaLly in the western part of China. In this case,the results from dispersions of seismic surface waves and other materials were considered. According to the Moho depth, the mainland of China can be divided into eight crustalblocks.The Moho depth is uniform and varies little inside the same block, while it changes abruptly from oneblock to another. The Tibetan Plateau is characterized by a thickest crust in the world. It may be due to thepenetration of indian crustal materials into the Tibetan crust or upper mantle. Deeper Moho in the neighbouringareas of Tibet may also be effected by the complicated collision processes between the two continents.Thin crusto f the North China Plain is considered to be related to the magmatic activities in the lower crust and uppermantle. While the crust of the eastern part of SOuth China may be due to the accretion of terrain from the oceanislands.展开更多
We obtained the 2-D P-wave velocity structure of the lithosphere in the eastern North China Craton, Shanxi fault subsidence zone, and Yinchuan-Hetao fault subsidence zone by ray tracking technology based on six groups...We obtained the 2-D P-wave velocity structure of the lithosphere in the eastern North China Craton, Shanxi fault subsidence zone, and Yinchuan-Hetao fault subsidence zone by ray tracking technology based on six groups of clearly identified crustal phases and one group of lithospheric interface reflection phases from seismic recording sections of 21 shots along the 1300-km-long Yancheng-Baotou deep seismic wide-angle reflection/refraction profile. The results indicate significant differences between the lithospheric structure east and west of the Taihang Mountains, which is a gravity-gradient zone as well as a zone of abrupt change in lithospheric thickness and a separation zone of different rock components. East of the Taihang Mountains, the Mesozoic and Cenozoic lithospheric structure of the North China Craton has undergone strong reformation and destruction, resulting in the lithosphere thickness decreasing to 70–80 km. The North China Basin has a very thick Cenozoic sedimentary cover and the deepest point of crystalline basement is about 7.0 km, with the crustal thickness decreasing to about 31.0 km. The crystalline basement of the Luxi uplift zone is relatively shallow with a depth of 1.0–2.0 km and crustal thickness of 33.0–35.0 km. The Subei Basin has a thicker Cenozoic sedimentary cover and the bottom of its crystalline basement is at about 5.0–6.0 km with a crustal thickness of 31.0–32.0 km. The Tanlu fault is a deep fracture which cuts the lithosphere with a significant velocity structure difference on either side of the fault. The Tanlu fault plays an important role in the lithospheric destruction in the eastern part of the North China Craton. West of the Taihang Mountains, the crustal thickness increases significantly. The crust thickness beneath the Shanxi fault depression zone is about 46 km, and there is a low-velocity structure with a velocity of less than 6.1 km s?? in the upper part of the middle crust. Combined with other geophysical study results, our data shows that the lithospheric destruction at the Shaanxi-Shanxi fault depression zone and the Yinchuan-Hetao rift surrounding the Ordos block is non-uniform. The lithosphere thickness is about 80–90 km in the Datong-Baotou area, 75–137 km at the Dingxiang-Shenmu region, and about 80–120 km in the Anyang-Yichuan area. The non-uniform lithospheric destruction may be related to the ancient tectonic zone surrounding the Ordos block. This zone experienced multi-period tectonic events in the long-term process of its tectonic evolution and was repeatedly transformed and weakened. The weakening level is related to the interactions with the Ordos block. The continental collision between the Cenozoic India and Eurasia plates and N-E thrusting by the Qinghai Tibet Plateau block is causing further reformation and reduction of the lithosphere.展开更多
文摘In the last decade, deep seismic sounding (DSS) of profiles several ten thousand kilometers in length has beenconducted in the mainland of China. A lot of results published in Chinese were compiled and a map of Mohodepth was presented in this paper. Coverage of DSS profile is not uniform,and is lacking in some areas, especiaLly in the western part of China. In this case,the results from dispersions of seismic surface waves and other materials were considered. According to the Moho depth, the mainland of China can be divided into eight crustalblocks.The Moho depth is uniform and varies little inside the same block, while it changes abruptly from oneblock to another. The Tibetan Plateau is characterized by a thickest crust in the world. It may be due to thepenetration of indian crustal materials into the Tibetan crust or upper mantle. Deeper Moho in the neighbouringareas of Tibet may also be effected by the complicated collision processes between the two continents.Thin crusto f the North China Plain is considered to be related to the magmatic activities in the lower crust and uppermantle. While the crust of the eastern part of SOuth China may be due to the accretion of terrain from the oceanislands.
基金supported by the National Natural Science Foundation of China(Grant Nos.91214205,41174052)the Special Scientific Research of Seismologic Industry(Grant No.200908001)
文摘We obtained the 2-D P-wave velocity structure of the lithosphere in the eastern North China Craton, Shanxi fault subsidence zone, and Yinchuan-Hetao fault subsidence zone by ray tracking technology based on six groups of clearly identified crustal phases and one group of lithospheric interface reflection phases from seismic recording sections of 21 shots along the 1300-km-long Yancheng-Baotou deep seismic wide-angle reflection/refraction profile. The results indicate significant differences between the lithospheric structure east and west of the Taihang Mountains, which is a gravity-gradient zone as well as a zone of abrupt change in lithospheric thickness and a separation zone of different rock components. East of the Taihang Mountains, the Mesozoic and Cenozoic lithospheric structure of the North China Craton has undergone strong reformation and destruction, resulting in the lithosphere thickness decreasing to 70–80 km. The North China Basin has a very thick Cenozoic sedimentary cover and the deepest point of crystalline basement is about 7.0 km, with the crustal thickness decreasing to about 31.0 km. The crystalline basement of the Luxi uplift zone is relatively shallow with a depth of 1.0–2.0 km and crustal thickness of 33.0–35.0 km. The Subei Basin has a thicker Cenozoic sedimentary cover and the bottom of its crystalline basement is at about 5.0–6.0 km with a crustal thickness of 31.0–32.0 km. The Tanlu fault is a deep fracture which cuts the lithosphere with a significant velocity structure difference on either side of the fault. The Tanlu fault plays an important role in the lithospheric destruction in the eastern part of the North China Craton. West of the Taihang Mountains, the crustal thickness increases significantly. The crust thickness beneath the Shanxi fault depression zone is about 46 km, and there is a low-velocity structure with a velocity of less than 6.1 km s?? in the upper part of the middle crust. Combined with other geophysical study results, our data shows that the lithospheric destruction at the Shaanxi-Shanxi fault depression zone and the Yinchuan-Hetao rift surrounding the Ordos block is non-uniform. The lithosphere thickness is about 80–90 km in the Datong-Baotou area, 75–137 km at the Dingxiang-Shenmu region, and about 80–120 km in the Anyang-Yichuan area. The non-uniform lithospheric destruction may be related to the ancient tectonic zone surrounding the Ordos block. This zone experienced multi-period tectonic events in the long-term process of its tectonic evolution and was repeatedly transformed and weakened. The weakening level is related to the interactions with the Ordos block. The continental collision between the Cenozoic India and Eurasia plates and N-E thrusting by the Qinghai Tibet Plateau block is causing further reformation and reduction of the lithosphere.
