四川竹鸡顶铜矿花岗细晶岩体地球化学特征及成矿潜力分析

GEOCHEMICAL FEATURES AND MINEROGENIC POTENTIALITY OF GRANITE APLITE IN ZHUJIDING COPPER DEPOSIT IN SICHUAN PROVINCE

竹鸡顶铜矿位于乡城大断裂上盘四道桥-竹鸡顶破背斜与三道桥-青达破背斜复合部位,是义敦岛弧带中部新发现的铜矿床,成因上与花岗细晶岩体密切相关.对竹鸡顶Ⅰ号花岗岩体的研究结果表明,w(SiO2)=64.05%～81.66%,σ=0.06～1.63,w(K2O+Na2O)=1.48～3.57%,A.R=1.26～2.93,属亚碱性岩体.微量元素地球化学特征表现为Rb,Th,Hf和U富集,Ba,Nb,Sr,P,Ti明显亏损.稀土元素总量变化较大,轻稀土相对富集,中等负Eu异常(δEu=0.4～0.7).岩体金属成矿元素含量较高,结合岩体氧逸度、挥发组分含量、围岩蚀变强度综合分析认为,竹鸡顶岩体具较强的铜成矿潜力.

Zhujiding copper deposit locates in the core of Sidaoqiao-Zhujiding anticline and Sandaoqiao-Qingda anticline in hangding walls of Xiangcheng fault.,which is a newly foundled copper deposit in the middle of the Yidun island arc and the genesis is closely related to the Granite aplite.Based on the geochemical research of number Ⅰgranite aplite ,the SiO2 is high：64.05%～81.66%;the Rittmann index （σ） is 0.06～1.63,average 0.46;the AR is 1.26～2.22,.the granites is subalkaline.Geochemistry of host granites in Zhujiding copper enriched Rb、Th、Hf and U, strong depletion in Ba、Nb、Sr,P,Ti.The varation of gross REE content is high, LREE is relatively rich and the fractionation of LREE is higher than HREE.Eu is medium depletion （δEu=0.4～0.7）.The content of metal metallogenic element is higher than upper crust.Combined with the research of oxygen fugacity, volatile component and wall rock alteration, it is suggested that the Zhujiding granit aplite have greater copper minerogenic potentiality.