陕西煎茶岭金矿区的岩石及成矿时代研究

A STUDY OF PETROLOGY AND METALLOGENETIC EPOCH OF GOLD IN JIANCHALING DEPOSIT,SHAANXI PROVINCE

陕西煎茶岭金矿区的超基性岩体侵位后，在后期强烈的构造－岩浆活动及富ＣＯ２流体作用下，超基性岩蚀变为纤胶蛇纹岩。后来在绿片岩－低角闪岩相的条件下发生了叶蛇纹石化的进变质作用，与此同时，基性岩蚀变为异剥钙榴岩。钠长斑岩中钠长石的Ｋ－Ａｒ年龄为３７２Ｍａ，基质年龄为３３７Ｍａ。它表明矿区内酸性岩浆活动主要时期是在３３７－４００Ｍａ之间。与金矿化关系密切的铬水云母Ｋ－Ａｒ年龄是１４４Ｍａ。它暗示本矿区的金矿化有可能形成于中－晚燕山期，并与后期的张裂活动有关。与蛇绿岩带蚀变超基性岩有关的金矿床，往往是与超基性岩侵位后该构造带长期的、反覆的多次构造－岩浆活动有关。

After the emplacement of ultrabasic rock in Jianchaling gold mine area,Shaanxi Province,the harzburgites were altered to serpentites under the action of CO2-rich fluid during the later structure-magma stage.Then,the progressive metamorphism of antigorite were happened in the rocks on the condition of green schist to low amphibolite facies,and the mafic rock in the area were metamorphized to form the rodingite.The K-Ar isotope age of albite phenocryst in albitophyre vein is 372Ma,while that of the ground mass in the rock is 337Ma.It means that the acid magmatic activity occurred mainly during 337-400Ma in this area.The K-Ar isotope age of chrome-hydromica associated with the gold mineralization is 144Ma.This implies that the metallogenetic epoch of gold in Jianchaling might be happened in Middle to Later Yanshan movement and related to the later tension of the deep-rift.The gold deposit related to the altered ultramafite of ophiolite is formed by the repeated actions of structure-magma in that structure zone over a long period of time.