塔里木盆地巴楚地区二叠纪以来构造应力场解析

STUDY ON STRUCTURAL STRESS FIELDS SINCE PERMIAN,BACHU AREA,TARIM BASIN

通过构造地质演化分析,将塔里木盆地西北部巴楚地区二叠纪以来具有较强构造变形的构造应力场分为3期:晚古生代二叠纪末、中生代三叠纪—古近纪和新生代新近纪以来。通过对巴楚地区岩墙、节理、擦痕、褶皱与断层等应力感构造的测量分析,对各时代地层中应力感构造的发育特征进行对比与分期总结,同时对节理等进行分期配套,发现巴楚地区二叠纪末最大主压应力方向为北西向,与中天山岛弧和塔里木板块的斜向碰撞有关;三叠纪—古近纪为北北东向,可能与侏罗纪塔里木盆地的顺时针旋转受到抑制有关;新近纪以来由于印度板块与欧亚板块相互碰撞,巴楚地区最大主压应力方向为南北向。利用二维有限元方法对巴楚地区新近纪构造应力场进行了数值模拟,模拟结果与实际情况拟合较好。

Three periods of structural stress fields can be recognized since Permian in northwest of Tarim Basin and adjacent areas based on structural evolution analysis,which is the end of Permian,the Triassic to paleogene and Neogene.Based on the research of stress-response structures of dykes,joints,slickensides,folds and faults,and analysis of the comparison characters of field of stress,it is found that the direction of the maximum principal stress formed by the collision of middle Tianshan island arc and Tarim basin was NW.The direction of maximum principal stress Triassic to paleogene was NNE,which developed by repression of dextrorotary of Tarim basin.And it was N-S direction since Neogene in Bachu area as a result of the collision of Indian plate with Eurasian plate.Furthermore,the authors simulated the stress field since Neogene based on 2D finite-element method,to deeply analyze the distribution and direction of stresses in the research area.