滇西羊拉铜矿叠加成因的地质地球化学依据

Geological and geochemical basis for superimposition genesis of the Yangla copper deposit in west Yunnan

产于金沙江结合带与维西晚古生代-早中生代火山弧交接部位加仁岩体北倾覆端羊拉铜矿,含矿岩系为泥盆系江边组和里农组,属一套火山岩、砂泥质硅质复理石建造,是火山-喷流沉积作用产物,形成(似)层状块状硫化物矿体;中-晚印支期中酸性岩侵入对原生层状矿体进行了叠加,形成了矽卡岩富厚矿体,里农矿段KT1和KT5层状矿体在产状、规模、分带性和矿物组构等方面与传统接触交代矽卡岩存在显著差异,并从矿物学、地球化学特征显示具明显同生矿化后期叠加改造特征,该期也可单独形成矽卡岩型矿体,及由钙铁榴石、钙铁辉石、阳起石、绿帘石等组成无矿化矽卡岩;晚印支-早燕山期形成NE向大脉状矿体,部分小型脉状斑岩型矿体。显示主要为三期叠加型矿床,是金沙江洋及其邻区构造演化在矿区的集中体现。根据矿体类型、保存条件及围岩性质等进行缺位预测、找矿与勘查。

The Yangla copper deposit is located in the Jingshajiang joining part with north overturn of Jiaren magmatic rock body at neopaleozoic-early Mesozoic volcanic arc connecting part, the ore-bearing stratum of which is Jiangbian group and Linong group of Devonian system belonging to a series of volcanic and sand-ar- gillaceous siliceous flysch formation resulted from volcanic-spouting sedimentary process, forming stratiform massive sulfide orebody~ the intrusion of intermediate-acidic magmatic rock bodies superimposed on the orig- inal stratiform orebodies forming thick scarn type orebody and non-mineralized skarn composed of kalkgranat, asteroite, aktinolith and acanticonite etc. Northeast striking big vein orebodies were formed dur- ing late Indo-Chinese epoch and early Yanshan period, with part of the small type vein porphyry orebody be- ing mainly superimposition ore deposit resulted from the structural evolution of Jinshajiang ocean and its ad- jacent area. Vacancy prediction, exploration and prospecting were carried out according to orebody type, re- serving condition and country rock characteristics.