大别变质地体的构造样式及变形序列

大别山区晚太古代大别群变质岩系,经历了复杂的变形过程。在大别变质地块内部识别出两套大型剪切带,它们在该区构造格架形成过程中起着重要的作用。本文还分析了变质的上壳岩、片麻岩和剪切带内的变形特点。实际资料说明,剪切带内的褶皱是由于剪切的不稳定性及平行面理局部缩短形成的,这些大型地壳剪切作用多伴随有挤压流动或伸展流动。根据褶皱叠加关系以及剪切带、新成体交切关系建立了大别群总体构造序列。该区提供了一个研究中下地壳作用的窗口。

TECTONIC STYLE AND DEFORMATIONAL SEQUENCE OF DABIE METAMORPHIC TERRANE

In the Dabieshan area, the late Archaean metamorphic rocks,here termed as the Dabie Group, are complexly deformed. Two sets of major shear belts are recognized, which played a very important role in the development of the tectonic framework of the Dabie metamorphic massif. The deformational characteristics of the metamorphic supracrustal rocks, gneisses and shear belts are analyzed respectively.The data show that the folds within these belts have developed from instability in the shear belt or from local components of foliation-parallel shortening.The major crustal shears may be often associated with compressional or extensional flow. A total deformation sequence of the Dabie Group is established, "using fold overprinting combined with shear belt and the cross-cutting neosomes. The results suggest that the area provides a window for the examination of mid-lower crustal processes.