DETERMINATION OF ACTIVE UNITS WITH DIFFERENT KINEMATIC PROPERTY AND THEIR ACTIVITY PATTERN IN NORTH CHINA BASED ON THE DATA FROM GPS REMEASUREMENTS

Yang Guohua; Han Yueping; Zhang Fenglan

doi:10.3321/j.issn:0253-3782.2001.01.001

Abstract：Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished, 4 active units and 1 transition zone with distinct differential movement have been determined. They are Ordos-Yinshan unit, Yanshan unit, Shanxi-Hebei-Shandong unit, Shandong-Liaoning unit and Yanshan-Hebei transition zone. The relative movements among the neighboring units in this period have been given.　① The compressive movement between Ordos -　Yinshan unit and Yanshan unit is not obvious with an amount of 0.4±1.3 mm/a. ② Shanxi-Hebei-Shandong unit moves E40°S off the Ordos-Yinshan unit and the magnitude is 4.4±1.0 mm/a. ③ Relative to the Yanshan-Hebei transition zone of differential movement, Yanshan unit shifts westwards 38° by north with a value of 2.4±1.3 mm/a and Shanxi-Hebei-Shandong unit moves eastward 35° by south with an amount of 2.3±0.9 mm/a. ④ Shanxi-Hebei-Shandong unit has a tensional left lateral movement of 4.7±1.4 mm/a in the direction of east 37° by south relative to Yanshan unit. ⑤ Some area near Tanlu belt which is located in the southern part of Shanxi-Hebei-Shandong block has a southward movement 14° by west with a magnitude of 1.5±1.1 mm/a off the Shanxi-Hebei-Shandong unit. ⑥ Relative to Shanxi-Hebei-Shandong unit, Shandong-Liaoning unit has a trend of clockwise movement with a tensional right-lateral motion at the north end which neighbors Yanshan unit and a compressive motion at the south end. It should be noted　that the errors given in the paper are obtained based on the divergence among the displacements of the sites in the unit, rather than the value calculated from the displacement error of the sites. The analyzed results indicate that: ① Shanxi tectonic zone and Yanshan-Hebei transition zone are the major tectonic active zones to show the frame and magnitude of interior ralative movement in North China area, and others are the secondary tectonic active zones; ② The complete horizontal deformation in the North Chine area is not homogeneous nor successive; ③ The kinetic model of North China area might be ″mantle dragging plus boundary coupling″.