闽西南广平推覆构造应力场特征及平衡剖面研究

Tectonic Stress Field Character and Balanced Cross Section of Guangping Thrust in Southeastern Fujian

摘要: 本文采用共轭剪节理应力反演方法及平衡剖面复原原理分析了闽西南广平推覆构造的运动学特征及变形缩短程度。通过对分布于广平推覆体林地组石英砂砾岩中9个测点的共轭剪节理测量结果分析，得出形成推覆构造的构造应力场最大主压应力为NW-SE向；通过对煤田勘探剖面开展平衡剖面研究，估算出由于推覆构造导致的地层缩短率为38.4%；结合推覆构造基本特征及区域构造综合分析，推断广平推覆构造在区域挤压应力作用下由NW向SE运动，并造成地层大幅缩短。以上结果表明闽西南及其所在的中国东南大陆岩石圈自晚中生代以来经历了强烈挤压变形，形成了自NW至SE向运移且规模巨大的推覆构造。

Abstract: With the backward method of the stress filed about the conjugate joints and the theory of balanced cross section, the writer analysed the kinematic characteristics and the deformation degree of the Guangping thrust. In accordance with the survey of conjugate joints in the quarts sandstone of Lindi formation in 9 places, we draw a conclusion that the direction of the maximum compressive principal stress is NW-SE; the balanced cross section of the coal district shows that strata shortened at a rate of 38.4%, and that shortening is the result of the thrust moving. Combined with the basic characters of nappe structure and the regional tectonic analysis, the thrust moved from northwest to southeast under the action of the regional compressive stress and result in a large scale of shortening. The above results indicated that the lithosphere of southeastern Fujian, as well as southeastern China experienced strong compressional deformation from the later Mesozoic, and moved with a large scale and a long distance from northwest to southeast.