渤海盆地的现今扩张运动

关于渤海盆地的扩张，前人已有很多研究成果.但是，对渤海盆地现今扩张的主方向，扩张的速率和笵围迄今还不清楚，本文试图探讨之.根据中国地壳运动观测网络GPS网1998~2004年的观测结果，建立了渤海盆地周围地区相对于欧亚板块的速度场.将该区划分为8个块体，建立了各块体的速度模型，得到该区的水平形变速度场和应变场.分析形变速度场和应变场的空间变化，发现渤海及周围地区呈现明显的NW-SE方向的双向扩张运动，扩张速率为2.5±1.8 mm/a.NW-SE与NE-SW方向扩张范围分别为310 km与 410 km.渤海盆地扩张的范围与华北地壳最薄的区域基本一致，这表明上地壳的扩张变形与上地幔的隆升密切相关，岩石圈减薄和岩浆上涌使上地壳发生拉张变形，使渤海地区发育成一个拉张盆地.

Current-day extending motion of Bohai Basin

About extension of Bohai Basin, our predecessors obtained very researching results. But the principal direction, rate and range of the extension of Bohai Basin realized no up to know. In the paper, we will investigate these problems. On the basis of GPS surveying results from the Crustal Motion Observation Network of China, we created the velocity field relative to Eurasia Plate in Bohai Basin and its surrounding area. We divided the area into 8 blocks, and created the velocity models of these blocks, obtained the horizontal deformation velocity field and strain field in this area. By analyzing the space variation of the deformation velocity field and strain field, it is found that the Bohai and its surrounding area appears to be marked by NW-ward and SE-ward extending motion with extending rate of 2.5±1.8 mm/a. The extending ranges of NW-SE-ward and NE-SW-ward are at 310km and 410km respectively. The extending ranges of Bohai Basin are basically consistent with crust thinnest area of North China which indicates that extending deformations of upper crust are close relative with rise of upper mantle. The lithosphere thins and magma up-wills which lead to that the tensile deformation of upper crust occurred, it take the area of Bohai generate to a tensile basin.