论雪峰山构造带中生代变形

ON THE MESOZOIC STRUCTURAL DEFORMATION OF THE XUEFENG MOUNTAIN TECTONIC ZONE IN HUNAN

雪峰山构造带于中生代发育两套相反的逆冲剪切推覆构造系统，它们是壳块不同演化时期多向运动变形的产物。会聚式地幔蠕动和扩散式的地幔蠕动所产生的岩石圈增厚和减薄，是引起中生代构造变形和活化的根本原因，太平洋壳体的西向碰撞、印度壳体的东向碰撞及周缘造山带的侧向挤出效应，则是不可忽略的外部因素。

Two sets of tectonic systems of thrust,shear and nappe structures of Mesozoic in opposite direction developed in the Xuefeng mountain tectonic zone.One of them occurred in the early Mesozoic(T 3-J 3)with northwest-trended polarity of tectonic intensity which reflected the dominance of deformation and thrust from NW to SE trend,and the shearing had the right-rotated nature.The other formed in the late Mesozoic(K 1-K 2)with southeast-trended polarity which was dominated by the SE-NW-trended thrust,nappe and uplift, and the shearing had the left-rotated nature.The complicated tectonic deformation and magmatism and the transformation of their natures are the result of multiple movement deformation during different evolution period of crustoblock.the original cause of Mesozoic continental activation may be thinning-thickening process of lithosphere brought into by setting extrusion-type or diffusation-type mantle creep-flow,the long-distance effect of the tectonic setting of the pro-Pacific,the Tethys setting and the margin orogenic belt would be the external factor inducing crustobody movement and deformation.