韩城矿区纵弯褶皱的几何学特征及其形成演化机理

Geometry and geodynamic mechanism of buckle folds in Hancheng mining area

褶皱构造是影响韩城矿区煤炭开采并控制瓦斯富集的地质因素之一。研究韩城矿区褶皱构造的几何学特征,揭示其形成演化机理,有助于深化对矿区地质构造发育规律的认识,有效地指导煤矿安全高效生产。在地质分析基础上应用趋势分析、平衡剖面分析和古构造应力-应变场数值反演等方法,对韩城矿区的纵弯褶皱进行了系统的构造解析。研究结果表明,印支期韩城矿区受到由南向北的水平挤压构造应力,形成南区的复式背斜和北区的复式向斜,以及次一级轴向近于东西的纵弯褶皱,南北向挤压收缩率南大北小;燕山期受到来自SE方向且比印支期更强烈的水平挤压构造应力,形成NE向的韩城倒转背斜及区内次级纵弯褶皱,北西向收缩率东大西小、北大南小;两期褶皱构造在北区横跨叠加复合效应明显,因而层滑构造和构造煤主要发育在北区。

Fold structure is one of geological factors affecting coal mining and controlling gas accumulation in Hancheng mining area.To investigate the geometry and geodynamic mechanism of buckle folds in Hancheng mining area is helpful for deepening the understanding on the geological structure development law and guiding coal mine production more effectively and safely.On the basis of geological analysis,the buckle folds of the research area is systematically analyzed,using such methods as trend analysis,balanced section analysis,numerical inversion of paleotectonic stress-strain fields.The main research results are as follows：In Indosinian period the horizontal compressive tectonic stress from south resulted in anticlinorium in south area and synclinorium in north area as well as secondary buckle folds with the axial direction nearly EW,and the shrinking rate was larger in the south area.The horizontal compressive tectonic stress in Yanshan period was more intense than one in Indosinian period,which came from SE direction and formed Hancheng overturned anticline and secondary buckle folds within the mining area with the axial direction NE,and the shrinking rate was larger in the eastnorth area.Bedding slip structure and tectonic coal were common in north area due to the across superimposing of the folds formed in the two periods.