冀西石湖金矿田古构造应力场数值模拟

石湖金矿田为中温热液型脉状矿床,构造裂隙的发育程度及产状是决定其矿床特征的主要因素。在进行构造解析的基础上,应用弹—塑性增量法对控矿构造进行了应力场数值模拟。综合分析表明:中侏罗世矿区主应力为NNW向,受NNE向边界断裂限制形成压剪性应力场,矿区处于应力高值区,岩石破裂形成了NW和近SN向共轭剪节理系,它们叠加于早期的复式背斜上,成为主要的容矿空间;晚侏罗世沿深断裂侵入的麻棚岩体使矿区围岩进一步变形,形成了不同位置的拉张区及挤压区,构造变形以对老构造的追踪和改造为主,新生裂隙较少;岩浆活动晚期成矿热液从深部沿深断裂由SE向NW运移,矿区内NW向节理走向与流体运移方向一致,且处于张性环境,成为首要的容矿空间及富集成矿区。

Numerical Simulation of Paleo-tectonic Stress Field of the Shihu Gold Ore-field in Western Hebei Province

Shihu gold mine belongs to hydrothermal mesothermal type vein deposits.The deposits’ characteristics are primarily determined by the degree of development of ore-controlling fractures and their occurrence. Conducting numerical simulation on the mine field’s tectonic stress field while applying the elastic-plasticity increment method,and in combination with tectonic analysis shows that：Subject to the effect of the torsional pressure stress field,the middle Jurassic mining area formed NW trending and similar SN trending conjugate shear joint system,they are superimposed on the early complex fold,and become the potential ore holding space. The late Jurassic epoch Mapeng intrusion intrudes along the deep fault,and to trace and transform the old tectonic and the new fracture is less.In later magmatic period,the metallogenic hydrothermal takes the deep fault as the channel to move from deep to shallow and from SE to NW,the NW trending joint trend is in conformance with the fluid moving direction,it is in an extensional environment becoming the primary ore holding space and the concentrated metallogenic area.