云南东川铜矿田面山—四棵树成矿带裂隙构造控矿规律

Metallogenic Regularity of Fracture Structure of Mianshan-Sikeshu Metallogenic Belt in Dongchuan Copper Orefield

云南东川铜矿田位于扬子板块西缘川滇铜多金属成矿带。东川铜矿区内面山—四棵树成矿带裂隙构造叠加成矿-控矿作用明显,但对其研究较薄弱。在对面山—四棵树成矿带坑道进行构造岩相学综合编录的基础上,结合区域地质背景,对典型中段的铜矿体进行裂隙要素测量,制作玫瑰花图进行分析并对岩相进行分带。研究表明:①面山—四棵树成矿带碱性铁质基性岩浆沿大角度切层断层侵入落雪组,由于岩浆的侵入挤压作用,侵入岩体与地层的接触带由内向外根据岩石变形程度可分为片理化相带→热液角砾岩相带→碎裂岩相带,其中,碎裂岩相带根据岩石碎裂程度由内向外可划分为强碎裂岩相带→碎裂岩相带→弱碎裂岩相带,铜矿品位也随之由高变低;②裂隙岩相学研究揭示主要存在3组含矿裂隙,走向分别为近EW向、近SN向和NEE向,其中近EW向裂隙(与地层产状基本一致)为最主要的含矿裂隙;③多期次的构造活动使岩石中裂隙发育程度高且交切关系复杂,以岩浆侵入改造成矿期为依据可将裂隙分为成矿前裂隙、成矿期裂隙和成矿后裂隙。通过对岩浆侵入-裂隙构造系统特征与成矿-控矿规律的研究,认为面山—四棵树成矿带侵入岩体附近的铜矿体受岩浆-裂隙构造系统改造富集作用明显,基性岩体附近碎裂岩相带为形成较高品位"裂隙矿"的有利靶区。

Dongchuan copper orefield in Yunnan Province is located in Sichuan- Yunnan copper polymetallic metallogenic belt at the western margin of the Yangtze plate.The fracture structure superimposition mineralization and metallogenic effects of Mianshan-Sikeshu metallogenic belt in Dongchuan copper orefield in Yunnan Province are obvious,but the study degree is relatively low.In view of the study shortage,based on the comprehensive cataloging of tectono-lithofacies in the tunnel of Mianshan- Sikeshu metallogenic belt,combined with regional geological background,the fracture elements of typical adit copper orebody are measured,and rose maps are made for analysis and lithofacies zoning.The study results show that:①the alkaline ferric basic magma intrudes into the Luoxue Formation along the large angle fault of Mianshan- Sikeshu metallogenic belt,due to the intrusive and compressive action of magma,the contact zone between intrusive rock mass and strata can be divided into schistose facies zone,hydrothermal breccia facies zone and fractured lithofacies zone from the inside to the outside according to the degree of rock deformation,according to the degree of rock fragmentation,the cataclastic lithofacies belt can be divided into strong cataclastic lithofacies belt,cataclastic lithofacies belt and weak cataclastic lithofacies belt from the inside to the outside,and the grade of copper deposit changes from high to low accordingly;②fractured petrography study reveals that there are mainly three groups of ore- bearing fractures near EW direction,near SN direction and NEE direction, among them,the near EW direction fracture(basically consistent with the occurrence of strata)is the main ore-bearing frac ture;③the multi-stage tectonic activities have resulted in high degree of fracture development and complicated intersecting relationship,according to the magma intrusion and transformation metallogenic period,the fractures can be divided into premetallogenic fracture,metallogenic stage fracture and post-metallogenic fracture.Based on above study of the characteristics of magmatic intrusive structure-fissure structure system and metallogenic-ore-controlling regularity,it is considered that the copper orebody near the intrusive rock mass of Mianshan-Sikeshu metallogenic belt is obviously enriched by the transformation of the magmatic-fissure tectonic system,and the cataclastic lithofacies belt near the basic rock is a favorable target area for the formation of high-grade fractured deposits.