临界角库伦楔在盐下楔状体的应用:以库车坳陷克拉苏构造带为例

摘要

临界角库伦楔模型的建立,确定了楔状体坡度与楔状体及底部滑脱层岩石力学性质之间的关系.但对于库车坳陷克拉苏构造带盐下发育的褶皱冲断带楔状体,由于有上层盐岩对楔状体的压力,临界角库伦楔模型的定量应用具有很大的局限性.文中考虑了上层盐岩的压力,推导出了适用于盐下楔状体的临界角库伦楔公式.根据重新推导后的临界角库伦楔公式对库车坳陷底部滑脱层的性质进行了计算,得出底部滑脱层内摩擦角为13.7°～18.4°,与泥岩或碳质页岩的性质相符.根据临界角库伦楔模型分析结果及地震资料解译,认为库车坳陷克拉苏构造带盐下楔状体的滑脱层为中下三叠统泥岩.%The model of critical taper wedge determines the relationship between the wedge slopes and the mechanical properties of the wedge and the basal detachment.However,for the subsalt structural wedge such as the Kelasu belt of Kuqa depression,due to the upper salt which puts pressure on the top of the Coulomb wedge,the quantitative application of the critical taper model has strong limitation.In this paper,considering the pressure of the upper salt,the critical taper formula applicable to subsah wedges is derived.According to the new critical taper formula,the internal friction angle of the Kuqa depression basal detachment is 13.7°～ 18.4°,which is consistent with mudstone or carbonaceous shale.Based on the results from critical taper analysis and seismic data interpretation,we suggest that the detachment of subsalt wedge of the Kelasu belt is primarily Middle-lower Triassic mudstone.