云南因民铁铜矿区辉长岩类侵入构造特征与找矿预测

Characteristics of Gabbro-Related Structures and their Prospecting Implications in the Yinmin Iron-Copper Deposit in Yunnan

对东川因民铁铜矿区辉长岩类侵入体的侵入构造几何学特征、物质组成和储矿构造样式进行研究,认为侵入构造特征复杂,辉长岩类以岩墙、岩床、岩株、岩枝和岩脉等产出,受落(雪)因(民)复式褶皱-断裂带核部及核部发育的SN向、NE向和NW向断裂控制,辉长岩类侵入体在空间上与铁铜矿体关系密切。从侵入构造中心向外具有三大构造岩相学分带,依次为侵入构造岩相带→热液蚀变角砾岩相带(体)→液压致裂-碎裂岩化相带,即侵入构造带(侵入角砾岩相带+含矿隐爆角砾岩相)→热液角砾岩体(筒)(热液角砾岩相+含矿热液角砾岩相)→断裂裂隙破碎带(含矿液压致裂角砾岩+含铜硫化物脉带)是本区主要含矿构造岩相带,是寻找和预测深部隐伏IOCG型矿体和热液型脉带状铜矿体的直接找矿预测标志。辉长岩类侵入体与落因复式褶皱-断裂带、小溜口岩组与因民组之间不整合面构造等形成了构造复合和储矿构造样式的多样性。本区储矿构造样式主要有辉长岩类侵入构造、隐爆角砾岩筒(带)和钠长石角砾岩筒(带),落因复式褶皱-断裂带与辉长岩类侵入体的复合叠加构造、辉长岩类侵入体与不整合面之间的叠加构造等,控制了不同类型矿化组合和矿床类型(成矿多样性)。在因民铁铜矿区深部小溜口岩组及落因背斜东翼,围绕辉长岩类侵入构造带是今后寻找IOCG矿床的主要靶位。

The gabbro intrusion-related structures are quite complex, which include dyke, sill, stock, and apophyses, in the Yinmin Fe-Cu deposit, Dongchuan. The spatial distribution of the iron-copper ore-bodies are closely related to gabbro intrusions. Both of ore bodies and gabbros were controlled by the secondary SN-trending, NW- and NE-trending fractures or faults developed in the core part of the Luoyin compound fault-fold belt. Three zones, i.e., intrusion-related structure lithofacies zone, hydrothermal alteration breccia lithofacies zone, and hydraulic crack-cataclastic lithofacies zone, are observed from the center of the intrusion-related structure to its rims. The three structure lithofacies zones are the major ore-bearing structures in the region. Therefore, these ore-bearing altered lithofacies zones are plausible loci for iron-oxide copper gold （IOCG） deposit and hydrothermal vein-type copper deposit prospecting. The main ore-hosted hosting structure styles are include the gabbro intrusion-related structures of gabbros, crypto-explosive breccia pipe, albite brecciated lithofacies zone, overprinting structure of the Luoyin compound fault-fold belt and intrusion-related structures of gabbros, superimposed structures between intrusion-related structures of gabbros and unconformity structure. All of them jointly controlled different styles of mineralization series and deposit-types （diversity of mineralization）. Therefore, the gabbro-related structures should be the priority target of the future exploration for the iron oxide copper-gold deposits in the Xiaoliukou Group （Ar3-Pt1x） and at the east wing of the Luoyin compound fault-fold belt in the Yinmin area.