黔南坳陷节理发育特征及其对构造应力场转换的指示

通过野外地质调查,统计和分析黔南坳陷节理产状、几何样式及序列关系等,探讨古构造应力场特征.结果表明:根据节理切割及其与断层的先后关系,可将黔南坳陷节理组分为5个序列,NNE与SEE向"X"型平面共轭剪节理在加里东末期首先发育,在燕山晚期发育NW-NE方向共轭剪节理和NNE-NEE方向共轭剪节理,且前者发育时间先于后者, EW向节理在喜马拉雅期形成;构造应力场主方向经历了NEE-NS-NE-EW的先逆时针后顺时针的应力场转换;燕山期和喜马拉雅期在黔南坳陷构造应力场转换中起着重要作用.

Growing characteristics of joints in Qiannan depression(Southern Guizhou) and its implication to tectonic stress field switch

The systematical statistical analysis on the joint occurrence, geometric patterns and sequences was carried out by field geology study, and the characteristics of palae-tectonic stress field were discussed. According to the joint cutting relationship and its chronological relation to faults, the joint set in Qiannan (Southern Guizhou) can be divided into five epochs in time chronological order: plane X conjugate shear joints with the direction of NNE and SEE which developed at late Caledonian stage, conjugate shear joints with the direction of NE-NW and with the direction of NNE-NEE developed at late Yanshanian, and EW joints developed at Himalayan stage. The principal direction of tectonic stress field experienced the switch from anti-clockwise to clockwise. The Yanshanian and Himalayan stages play a significant role in the switch of tectonic stress field in Qiannan (Southern Guizhou).