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STRIP-SHAPED TECTONIC DIVIS10N 0F C0NTEM P0RARY LITH0SPHERIC STRUCTURE 0F EASTERN CHINA

Ma Zong-jin, Wang Guo-quan   

  1. Institute of Geology, China Seismological Bureau, Beijing, 100029
  • Received:1999-03-20 Revised:1999-03-20 Online:1999-03-20 Published:1999-03-20

Abstract: Separated by the Yinchuan-Kunming line(105°± 2°E), the eastern and western parts of the China continent are different sharply from each other in lithospheric structure as wel1 as in other features. These two parts can be further divided into many secondary tectonic units according to features of mountains and rivers, neotectonic faults, earthquakes, gravity, thickness of earth crust, geomagnetic anomaly and high-conduct layers. In this paper, based primarily on the features of earthquake intensity and frequency, as well as a comprehensive analysis of data about the preferred arrangement direction of epieentra1 density, strikes of mountains and rivers, neotectonic faults, gravity, geomagnetic and high-conduct layes, we divide the eastern China into seven secondary tectonic units: North-Fast(north)region, North-Fast(south)region, large North China region, Central China(Middle and Lower reaches of Yangtze River)region, South China (north)region, South China (south)region and South Chin Sea region. The south boundaries of each secondary tectonic unit are respectively 47°N tectonic 1ine. Yinshan tectonic belt, 34°N tectonic line, Beiling tectonic belt, Nanling tectonic belt and 20° N tectonic line. The basic features of these regions are characterized by nearly west-east trending, with an width about five degrees of latitudes, parallelly ranging, and great differences in lithospheric structure, history and intensity of tectonic deformation. We name them as the strip-shaped tectonic regions. reflecting the subdivision of eastern China. If regarded as a part of secondary tectonic of south-east region of Eurasian continent plate, they can be analogized with a series of parallel suboceanic strip-shaped tectonics of the Fast Pacific Ocean and the Atlantic Ocean, which were caused by suboceanic transform faults. These suboceanic strip-shaped tectonics have very small differences in 1and features. But these strip-shaped tectonics in continental plate are more complicated, because they are different from each other in evolutionary history and physical composition. If these EW-striking continental lath-shaped units have been affected by the force from the Pacific plate, i.e. from east or nearly east since the later Mesozoic, then the active mode is a parallel active mode corresponding to the striking of lath, shaped unit, and the mode is favorable to bring about differential deformation caused by their own difference. In eastern China, shallow morphostructure deep structure of crust and lithosphere, as wel1 as the high conduct-layer, all resulted from the merging of the early Mesozoic continents and intensive deformation of the late Mesozoic continents. The main tectonic direction controlling the whole region is the NE-striking, and the NE-striking and NW-striking tectonics conjugate with each other. A series of en echelon morphostructures developed in the boundary area between every pair of secondary region, which was caused by relative movement of the secondary units. In this paper, based oil the features of 1oeation an d stretch, we name Wuling Mountain, Mufu Mountain, Jiuling Mountain, Huaiyu Mountain and Xianxia Mountain, etc. as a whole the Beiling Mountain belt corresponding to the name of the Nanling Mountain belt. The Beiling Mountain belt is the boundary between south China(north)region and centra1 China region.