沁水盆地南缘中-新生代构造变形与构造应力场

摘要

沁水盆地南缘自中生代以来，主要经历了印支期、燕山期、喜马拉雅期三期构造活动的影响。通过对地表露头的断层面擦痕、纵弯褶皱及共轭节理系的研究，获得了古构造应力场信息。在研究区东部NNE向的太行山断裂带内，逆冲挤压构造非常明显，与其相伴发育的不对称背斜构造表明其主压应力方向为110°；中部的EW向正断层、地堑系可能是印支期近SN向挤压作用下形成的逆冲构造经历了新生代构造反转作用而产生的，新生代伸展作用非常显著，伸展方向为26°，249°，347°；西部边界由近SN向断裂组成，存在新生代近EW及NEE-SSW向伸展运动的擦痕证据，伸展方向为94°，72°。区内发育NNW-SSE，NW-SE，NE-SW，NEE-SWW，近SN等几个方向的共轭节理系，表明存在过燕山期NW-SE向的水平挤压构造应力场和喜山期NE-SW向水平挤压构造应力场，近EW向水平挤压应力场可能是在这两期主要构造应力场转换过程中形成的。%The southern margin of Qinshui basin has mainly experienced three periods of tectonic activities since the Mesozoic:Indosinian, Yanshanian, Himalayan. Palaeotectonic stress field data have been obtained by analyzing the striation, buckle fold, and conjugated joint system in outcrop. In the east, the thrust compressing structure is evident within the NNE trending Taihangshan Fault Belt and the associated asymmetrical anticline shows 110° trending compression. In the central, the EW trending normal fault and graben system were probably produced by the SN trending compression in Indosinian and the subsequent tectonic inversion in the Cenozoic. The Cenozoic extension is very significant and the extension azimuth is 26° , 249° and 347° , respectively. The nearly SN striking faults composite the west boundary of the Qinshui basin, striation evidence of the nearly WE and the NEE-SWW trending extension has been gained and the extension azimuth is 94° and 72° . NNW-SSE, NW-SE, NE-SW, NEE-SWW and nearly SN striking conjugate joint systems exist in our study area. NW-SE trending horizontal compressive tectonic stress field of Yanshanian and NE-SW trending horizontal compressive tectonic stress field of Himalayan could be gained by the conjugated joints systems. The nearly EW trending horizontal compressive tectonic stress field was probably formed during the process of the conversion of the two main tectonic stress field.