大青山逆冲推覆构造带中劈理特征及其成因

在大青山逆冲推覆构造带中发育一组非透入性板劈理构造，主要发育有两种劈理，分布在中部构造岩片和外缘构造带中。第一种劈理分布在主干逆冲断层下盘，受断层控制，为一组压扭性构造面，其产状、变形特征和滑动方向与主干逆冲断层相一致；第二种劈理为层间劈理，受岩性控制。沿着劈理面同构造新生矿物组合和碎屑颗粒变形特征表明,劈理形成于地壳中浅部构造层次上的低绿片岩相条件下，以韧脆性变形机制为主。劈理切割了大青山褶皱构造，形成时代为(121.6±1.6) Ma。应力场的分析表明，劈理构造由近南北向的地壳水平挤压应力作用形成。

The Characteristics and Genesis of Cleavage in Daqingshan Thrust

A group of non penetrative cleavages developed in Daqingshan thrust. There are two different cleavages in the middle structural slice and in the outer structural zone. The first group of clea vage, being distributed at the footwall of main thrust and controlled by faults, behaves as a set of compressive planes whose occurrence, deformation characteristics and slipping direction are consistent with that of the main thrust . The second group belongs to interbeded cleavage controlled by lithology. Newly formed syntectonic mineral assemblage along cleavage plane and clastic grain deformation characteristics indicates that the cleavages were formed at the low greenschist facies conditions in the middle upper crustal level and were featured by ductile brittle deformation. Cleavages, being (121.6±1.6) Ma, has cut the Daqingshan folding. The stress field analysis showed that the cleavages formed under horizontal, S-N trending compressive stress.