压性构造对岩溶发育的控制作用--以贵州普定地区为例

Compressive Structure's Control on the Karst Development

笔者等在贵州普定进行野外水文地质调查时发现,这一地区向斜轴部有地下河和溶洞发育,有的沿较大规模的压性断层带发育,其走向与褶皱轴线或压性断层走向一致,对此做了一些探讨和研究。研究结果显示,在构造应力场作用下,岩层变形逐渐加大,继而形成构造形迹—向斜构造,同时伴随发育的压性断裂,在其轴部局部应力场作用下,上部继续受压,下部转为拉张,且产生放射状张裂隙;而规模大的压性断层,如逆断层等,其断层带受强烈挤压破碎,具有隔水作用,断层上盘的拖曳褶皱使岩层中张裂隙发育。该类张性裂隙有利于地下水的赋存、径流和岩溶发育。这是对传统地质构造控制岩溶认识的一个完善和推进。

Based on karst hydrogeological investigation, there are many underground rivers and caves developed in the synclinal axis, and some are developed along large-scale compressive fault zone in Puding county, Guizhou province, their trend agrees with synclinal axis and compressive fault. Their mechanism of compressive Structure＇s control on the karst development had been explored in this paper. Under the action of tectonic stress field, the distortion of rock bed gradually increased, and then the syncline formed, meanwhile, due to local stress of the synclinal axis, the upper rock bed of the syncline continued to be compressive, and the lower rock bed of the syncline turned to be tensile, and the radial tensile cracks formed. At the large scale compressive fault, such as thrust fault, the fault zone were mightily compressed and cracked, and obstructed water. Because of the towed fold of compressive fault, the tensile cracks of hanging block were developed. This kind of the tensile cracks were beneficial to the occurrence and flow of groundwater and karst development. It gives great impetus to the knowledge of geological structure controlling karst development.