【摘要】 沿扬子地块西缘出露的一系列变质杂岩的构造性质及形成时代是分析华南地块大地构造属性的关键。这些杂岩均被初始为低角度的正断层所围限 ,具有变质核杂岩的构造性质 ,其剥露时间在177Ma左右。目前 ,对这一区域几个代表性杂岩体进行的系统的岩石学和地球化学分析表明 ,这是一套主体为与俯冲板块有关的岛弧型岩浆杂岩 ,其形成时代从 72 6～ 86 4Ma ,时间跨度在 10 0Ma以上。证明这些岩石的形成与地幔柱作用无关。上述结果与最近在Madagascar东北缘、Seychelles岛及印度的Malani的一条类似的变质岩浆杂岩带的地球化学与地质年代学研究结果完全吻合 ,这个构造带被解释为一条沿Mozambique洋东缘的巨大的向东俯冲的安第斯型俯冲 岩浆岛弧带。据此我们推测在Rodinia古大陆中 ,华南地块位于印度板块东北缘 ,其南东则可能与澳大利亚相接。更多还原

【Abstract】 There are numerous metamorphic complexes along the western margin of the Yangtze Block. Their structural styles and geochronology are the key to understanding the tectonics of South China Blocks (the Yangtze Block in northwest and the Cathaysian Block in southeast).Our recent studies indicate that the complexes were uplifted at about 177 Ma.Some of the gneissic complexes were metamorphic products of Neoproterozoic arc\| and subduction\|related igneous rocks with ages ranging from 726Ma to 864Ma.The Jinning granites with identical ages are also typical of arc\|related intrusions.Thus, our study does not support a previous model involving a mantle plume to form the Jinning granites around the Yangtze Block.This suggests that the western margin of the Yangtze Block was an active margin in the Rodinian reconstruction.Recent geochemical and geochronological studies of Tucker et al. also demonstrate that the metamorphic\|magmatic complexes in northeastern Madagascar, Seychelles island and Malani in India formed in a similar tectonic setting and represent an active Andean\|type margin on the edge of Rodinia.We therefore correlate the western margin of the Yangtze Block with the northeastern margin of the India Plate, both being an active arc above an eastward subduction zone.This new configuration of South China in Rodinia is significantly different from the previously suggested one that South China was placed in an intracratonic setting between eastern Australia and western Laurantia.更多还原