山东沂南金矿金场矿区断裂构造特征与古应力场恢复

为深入研究沂南金矿金场矿区构造特征及动力学机制,恢复该区域的古构造应力场,为矿区深部找矿及工程布设提供依据,对金场矿区马旺矿段及冶官墓矿段进行了详细的地质调查,运用赤平投影方法,恢复了矿区不同地质历史时期的构造主应力优选方位,并结合区域地质背景资料,对矿区构造特征、古构造应力场的演化系列进行了综合分析。研究表明:①矿区自中生代成矿以来至少经历了3期挤压变形,分别为白垩纪早期的近SN向挤压变形,白垩纪晚期的近EW向挤压变形及新近纪的近NE-SW向挤压变形,3期挤压应力逐渐减小,最终形成了矿区大量集中于NW、NE、NNE3个延伸方位的剪节理或断层以及断层交汇形成的"入"字形与"人"字形的断裂构造格架;②赋存于断层带间的矿体在经历多期应力挤压变形后,其围岩稳定性较差,对后期巷道支护布设及采场设计参数优化提出了较高要求。

Characteristics of Fault Structure and Restoration of Paleo-stress Field in Jinchang Mining Area of Yinan Gold Mine,Shandong Province

In order to fully study the structural characteristics and dynamic mechanism in Jinchang mining area of Yinan Gold Mine,restore the paleo-stress field in the area and provide basis for deep prospecting and engineering layout in the mining area,detailed geological survey of the Mawang ore section and Yeguanmu ore section of the mining area are carried out.By using the stereographic projection method,the optimum direction of tectonic principal stress in different geological his tory periods of the mining area is restored,and combined with the regional geological background data,the structural charac teristics and evolution series of paleo-stress field of the mining area are analyzed synthetically.The study results show that:① the mining area has experienced at least three stages of extrusion deformation since the Mesozoic metallogenesis,that is,the near SN direction extrusion deformation in the Early Cretaceous,the near EW direction extrusion deformation in the Late Cre taceous and the near NE-SW direction extrusion in the Neogene,the three-stage extrusion stress is gradually reduced,finally, a large number of shear joints or faults in the extensions of NW,NE and NNE and a minefield fault framework formed by the intersectional faults in the mining area are formed;② stability of the surrounding rock of the orebodies hosed in the fault zones is poor after undergoing multi-stage stress extrusion deformation,therefore,the higher requirements for the layout of the road way support and optimization of the design parameters in the stope are provided.