东秦岭地区的地壳速度结构

VELOCITY STRUCTURE OF THE CRUST IN EASTERN QINLING MOUNTAIN

对横穿秦岭东段的人工地震测深剖面进行二维射线追踪处理，得到了该剖面上的二维速度结构图。由此获知该地区的地壳呈多层结构。上层地壳的Ｐ波速度为４．０～５．５ｋｍ／ｓ；中层地壳中有低速层出现；下层地壳的速度变化不大，约为６．５～６．９ｋｍ／ｓ。在深部可能有三个错断莫霍面的断裂带。地壳中的速度出现分层的特点，可能是由大的推覆构造所致。

A seismic sounding profile crossing the eastern Qinling Mountain was performed in the Western Henan Province, China. The data are interpreted with 2-D model in this paper. Our results show that the crustal structure are composed of several layers. The upper crust has variation of velocity from 4.0hm/s to 5. 5km/s. A LVZ occurs in the middle crust,and a little change of velocity (6. 5～6. 9km/s) exists in the lower crust. Three deep faults cutting the Moho discontinuity are also exhibited. These features reflect the thrusting reconstruction of tectonics of this area.