柴胡栏子金矿黄铁矿的化学成分标型特征及其矿床学意义

Typomorphic Characteristics of Chemical Composition of Pyrite in Chaihulanzi Gold Deposit and Its Mineralogy Significance

柴胡栏子金矿目前保有储量已不能满足金矿持续生产的需要,应开展进一步深边部找矿工作。基于成因矿物学理论,采用矿物地球化学方法对矿区内黄铁矿化学成分标型特征进行了研究。结果表明:(1)黄铁矿中Co/Ni元素比值和As-Co-Ni元素三角图解显示,柴胡栏子金矿黄铁矿成因较复杂,受建平群、区域变质和岩浆热液活动等诸多因素的制约;(2)黄铁矿中Au/Ag和S/Se等特征值显示出岩浆热液特征,表明成矿流体的形成主要与矿区岩浆活动有关;(3)黄铁矿晶体中的金以纳米微粒金存在,因纳米金具有较强的迁移性以及被碳质吸附的特性,因此矿区含碳质较高的绢云母化含石墨斜长片麻岩是最有利的赋矿围岩。依据矿区黄铁矿成分特征,结合区域地质、矿区地质及蚀变带特征,得出柴胡栏子金矿形成受诸多因素的联合控制,矿区基性岩脉侵入活动是重要的因素,基性岩脉不仅带来部分矿源,而且其携带的岩浆热液使建平群中的金(这部分金已在区域变质过程中得到活化)进一步活化而进入成矿流体中,在NNE向挤压构造带和NWW向张性裂隙构造带的交会部位,成矿流体与围岩广泛交代形成以蚀变岩型为主的金矿床,矿区东南部深部建平群老变质岩地层具有较好的找矿前景,尤其是绢云母化含石墨斜长片麻岩中的构造发育部位。

The current reserves of the Chaihulanzi gold deposit can not meet the needs of continuous production of the gold mine,and further deep-edge prospecting should be carried out.Based on the theory of genetic mineralogy,the typomorphic characteristics of pyrite chemical composition in the the mining area were studied by mineral geochemistry method.The results are as follows:(1)The ratio of Co/Ni and the As-Co-Ni triangle diagram of pyrite show that the genesis of pyrite in Chaihulanzi gold deposit is complex,which is restricted by the strata of Jianping Group,regional metamorphism and magmatic hydrothermal activity;(2)The ratio of Au/Ag,S/Se and other characteristic values of pyrite show the characteristics of magmatic hydrothermal solution and the formation of ore-forming fluid is mainly related to the magmatic activity in this area;(3)Pyrite is rich in As,which indicates that gold in pyrite crystal exists as nano-particle gold,which indicates that ore-forming fluid has strong migration and the nano-particle gold has strong adsorption in rocks rich in carbon and clay.According to the composition characteristics of pyrite,combined with regional geology,mining area geology and the characteristics of the alteration zone,it is concluded that the Chaihulanzi gold deposit is mainly related to the intrusion of basic dikes.The basic vein not only brings some ore sources,but also the magmatic hydrothermal fluid brings gold in Jianping Group to further activate and enter into the ore-forming fluid.At the joint of NNE trending compression structural belt and NWW tensile fracture structural zone,the ore-forming fluid and surrounding rock are widely metasomated to form a gold deposit with altered rock type as the main part.There are good prospecting prospects in the deep metamorphic strata of Jianping Group in the southeast of the mining area,especially in the structural development part of the sericite graphite-bearing plagioclase gneisses.