大别山古缝合线的研究

<正> 大别山地区北西西—东西向古构造边界的研究,是在李春昱先生的热情指导和支持下进行的,通过大量实际资料充分地证明了在晋宁旋回期间,这里曾发生古华夏大洋板块向北的俯冲并消减到古中朝大陆板块之下,在大别山地区形成一条缝合线。在这条构造线上,有发育较好的蛇绿杂岩,成线型分布。它的南侧有蓝闪片岩相、榴辉岩相低温高压变质杂岩带。地球物理资料证明该区为一“阻隔”带。

A STUDY ON THE PALEOSUTURE IN THE DABIE MOUNTAIN

The regional metamorphic belts, ophiolites and tectonics have been discussed in this paper. The EW-NWW suture line resulted from the subdu-ction of the southera Cathaysian oceanic paleoplate towards the northern Si-no-Korean continental paleoplate during the Jinning cycle, the evidence of which is given by the formation of glaucophane-schist and eclogite facies, granulite and almandine-amphibolite facies and greenschist facies which are respectively found in the southern, middle and northern parts of the area. Ophiolites are exposed along the belts of intense tectonism. They occur along Dabie geosutures and are thought to mark the sites of ancient zones of interaction between oceanic and continental crust. Thus, ophiolites are pre-served along the convergent plate margins although they are generated at the accreting plate margins.Seismological studies have made major contributions to our understanding of the structure and dynamics of the Dabie paleosuture belt.The relationship between the average thickness of the earth crust obtained from Rayleigh-wave dispersion and the surface topography is discussed. It is agreed that the crust in this area may be divided into two separate regions, the north and the south, each being an independent isostatic system at the depth of Moho discontinuity.