摘要
本文以太行山为界将华北地区分为东西两部分,东部为河淮块体,西部为鄂尔多斯块体.利用最小二乘法,从混合路径基阶瑞利面波群速度频散提取两块体的纯路径频散,并反演其地壳、上地幔的层状结构.所得结表果明,两块体的面波频散和地壳、上地幔结构存在明显差异.东部的河淮块体地壳较薄,地壳内平均速度比西部的鄂尔多斯块体壳内平均速度约低0.13km/s,壳内20km深度左右出现低速层;而西部的块体壳内速度成层递增,未见低速层出现.两块体上地幔顶部速度均偏低,地幔低速层的埋藏深度基本相同.但西部块体地幔低速层厚,且比东部块体地幔低速层的速度约低0.3km/s.
The North China region is roughly divided by the Tai Hang Mountains into two geological blocks: Eerduosi block in the west and the Hehuai block in the east. A least squares technique is applied to extract the pure path group velocities in the two blocks. From mixed path Ray-leigh wave group velocities of fundamantal model. Numerical inversion from the pure path group velocity dispersion is made to study the layered structures of the crust and upper mantle in the two blocks. The results of this work show considerable differences between the two blocks in surface wave dispersion and velocity structures of the crust and upper mantle. Hehuai block has a smaller crustal thickness and a mean velocity of approximately 0-13 km/s, smaller than that in Eerduosi block. And a low velocity zone seems appear at a depth of about 20 km. However Eerduosi block has a layered structure with gradually increasing velocities with depth. Low velocity zone has not been found in the crust. Both of the blocks have a relatively low velocity at the top of the upper mantle, and a similar depth of low velocity zone in the mantle. Eerduosi block has a thicker low velocity zone in the upper mantle, while its velocity is 0.3 km/s smaller than Hehuai block.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第4期417-423,共7页
Chinese Journal of Geophysics
关键词
地壳
上地幔
结构
横向
非均匀性
Surface wave dispersion, Irversion, Crust and upper mantle structures, Lateral heterogenity, North China.
