福建上杭县罗卜岭斑岩型铜矿蚀变、矿化分带及找矿标志

The Characteristics of Alteration and Mineralization Zone and the Prospecting Indicator in the Luoboling Porphyry Cu-Mo Deposit,Shanghang,Fujian

罗卜岭大型斑岩铜(钼)矿床位于福建省上杭县紫金山矿田的北东部,受区域性北东向构造和北西向构造断裂交汇以及燕山晚期岩浆侵位的双重控制。矿体主要赋存在似斑状花岗闪长岩外接触带的罗卜岭花岗闪长斑岩和四坊花岗闪长岩中,平面上呈半环形展布,空间上呈马鞍状向外侧展布。矿石中金属矿物主要为黄铜矿、辉钼矿和黄铁矿,主要有用组分为Cu、Mo,垂向上呈上铜下钼的空间分布特征。本区发育一套典型的斑岩型蚀变,以似斑状花岗闪长岩为中心,从中心至边部,从深部至浅表,大致可划分出四个蚀变带,包括(弱)钾化-绢英岩化蚀变带→(弱)绿泥石化-绢英岩化蚀变带→高岭石化-黄铁绢英岩化蚀变带→地开石化-硅化蚀变带。本区内,花岗闪长斑岩、(弱)钾化、绿泥石化-绢英岩化蚀变带、黄铁矿+黄铜矿+绿泥石脉、铁帽等是该矿床重要的找矿标志;而正磁异常与负磁异常之间过渡区域、区域性构造交汇部位是该矿床有利的找矿靶区。

The Luoboling porphyry Cu-Mo deposit is located in the northeast of the Zijinshan ore field,doubly controlled by the intersection of NNE and NW tectonic fault and the late Mesozoic magma emplacement.In the deposit,major porphyry orebodies are hosted in the Luoboling granodioritic porphyry and Sifang granodiorite out of the porphyritic granodiorite,with the shape of the semi-circular on the plane and spreading out in saddle shape.The ore mineral assemblage is chalcopyrite-molybdenite-pyrite,with the useful constituent of Cu and Mo,showing that molybdenum under copper vertically.There is a set of typical porphyry alteration,the porphyritic granodiorite as the center,from center to edge,from deep to shallow,can be roughly divided into four alteration zone,including the (weak) potassic alteration + silicification + sericitization-(weak) chloritization + silicification + sericitization-kaolinization + pyritization + silicification + sericitization-dickite + silicification.In this area,granodioritic porphyry,(weak) potassic alteration,chloritization + sericitizaton zone,pyrite + chalcopyrite + chlorite vein,gozzan,etc.,all are the important prospecting indicators of the deposit.And the transition region between the geophysical positive and negative anomalies,the regional structure intersection,are the favorable prospecting target area in the deposit.