江西德兴铜厂斑岩铜矿床细脉型矿体含矿裂隙系统研究

Study on ore-bearing fracture system of veinlet orebody in Tongchang porphyry copper deposit,Dexing of Jiangxi

江西德兴铜厂铜矿是中国东部最大的斑岩型铜矿床,该矿床主要由成矿岩体内带的浸染状矿体和外带的细脉型矿体组成,对于该矿床控制细脉型矿体就位及展布的控矿构造研究甚少。文章通过对露天采场和钻孔岩芯含矿裂隙特征的调查,结合前人对含矿脉体产状的统计资料,重新厘定了含矿裂隙系统,构建了控矿构造模型。研究结果显示,德兴铜厂铜矿床细脉型矿体的含矿裂隙走向整体上是围绕北西向拉长的梨形状成矿岩体周边呈放射状展布;同一部位含矿构造具有走向相近、中等倾角、双倾向和正断运动的特征,构成剖面X-型共轭剪裂隙组合。这些含矿裂隙形成于成矿岩体侵位时期,形成时最大主压应力近直立,中间主应力近水平且垂直成矿岩体边界,最小主应力近水平且平行于成矿岩体边界。铜厂铜矿床的控矿构造是长轴呈北西向展布的成矿花岗闪长岩的岩体侵入构造体系。进一步找矿方向是在矿区范围的北西向成矿岩体南东、北西两端存在隐伏岩脊部位的深部寻找细脉型隐伏矿体,在矿田、矿集区范围是寻找隐伏成矿岩体发育的部位。

The Tongchang copper mine in Dexing,Jiangxi Province,is the largest porphyry copper deposit in eastern China.The deposit is mainly composed of disseminated ore bodies in the inner contact zone of the ore-forming granodiorite body and veinlet ore bodies in the outer contact zone of the body.There is little research on ore-controlling structures that control the emplacement and distribution of veinlet ore bodies in the deposit.In this paper,through investigating the characteristics of ore-bearing fractures in open pit and borehole cores,and combined with the statistical data of previous studies on ore-bearing vein occurrence,the ore-bearing fracture system is studied.The research results show that the ore-bearing structure of veinlet-type orebody in the Tongchang copper deposit in Dexing is distributed radially around the periphery of NW elongated pear-shaped ore-forming granodiorite body.The ore-bearing structures in the same position are characterized by similar strike normal fault with opposite dipping at medium dip angle,which constitute X-type conjugate shear fracture combination in section.They formed in the emplacement period of ore-forming granodiorite body.The maximum principal compressive stress is nearly vertical,the intermediate principal stress is nearly horizontal and vertical to ore-forming granodiorite body boundary,and the minimum principal stress is nearly horizontal and parallel to the boundary.The orecontrolling structure of the Tongchang copper deposit is the magmatic intrusion structure system of ore-forming granodiorite body with its long axis distributed in NW direction.The further prospecting direction is to look for veinlet type concealed ore bodies in the deep part where there are concealed rock ridges at the southeast and northwest ends of NW-trending metallogenic granodiorite body in the mining area,and to look for concealed metallogenic granodiorite body in the ore fields and ore concentration area.