杏树岗地区正向反转构造与裂缝研究

Study of positive inversion structure and fracture in Xingshugang area

杏树岗地区主要经历了拉张沉降期和反转构造期。拉张沉降期杏树岗地区主要形成NNW向的高角度正断层,同时泉头组地层形成了一组NW向的拉张破裂裂缝;反转构造期杏树岗地区主要形成呈NNE-NNW向展布的正断式反转构造,同时泉头组地层形成了一组近NE向的纵张缝、一组NW向的拉张破裂缝和近NS、NNW向的两组共轭剪裂缝。沉降期间泉头组地层的沉积物基本处于塑性状态,构造裂缝不发育,且此期间形成的构造裂缝经历了较长时间的成岩作用,多被方解石充填,有效性低。反转构造期间泉头组地层已经成岩,在挤压作用下形成了一系列构造裂缝,该时期形成的裂缝以高角度裂缝和直裂缝为主,充填程度较低。反转构造期是杏树岗地区构造裂缝形成的主要时期。

Xingshugang area has principally experienced extensional settlement and reverse stages.The nnw-trending high-angle normal faults and nnw-trending tension fractures were formed in Quantou formation in extensional settlement stage of Xingshugang area. The nne-nnw trending positive inversion tectonics and ne-trending longitudinal fracture and nw-trending tension fracture and ns-trending and nnw-trending conjugate shear fracture were formed in Quantou formation in reverse stage of Xingshugang area. Sediments of Quantou formation was in plastic state in extensional settlement stage and the tectonic fractures were poorly developed, the fracture has experienced a long time of diagenesis and filled by calcite mostly and with low efficiency. Quantou formation has consolidated into rocks and a series of tectonic fractures have formed in reverse stage. Fractures formed in this stage were mainly of high aperture and vertical fractures, and with low degree of filling. The reverse stage is the main stage of forming fractures in Xingshugang area.