甘肃桦树沟铜矿床成矿年龄讨论  

Discussion on Metallogenic Age of Huashugou Copper Deposit in Gansu

作　　者：赵东宏[1] 杨合群[1] 刘玉琳[2] 王方成 

机构地区：[1]西安地质矿产研究所,陕西西安710054 [2]北京大学,北京100871 [3]甘肃省地质矿产勘查开发局,甘肃兰州730000

出　　处：《矿床地质》2003年第2期134-140,共7页Mineral Deposits

基　　金：北祁连山西段铜矿床成矿模式及找矿预测研究课题 (编号 :95_0 2_0 0 4_0 2 )的部分成果

摘　　要：桦树沟铜矿床是近年来在北祁连山西段镜铁山矿田发现的一种新类型铜矿床。作者在矿床区域地质背景、地质特征分析的基础上 ,通过对与成矿密切相关的石英闪长岩脉中的锆石U_Pb同位素年龄及蚀变岩型铜矿石的40 Ar_3 9Ar同位素年龄测定 ,认为桦树沟铜矿床是在元古宙铜预富集的基础上 ,富含铜元素的条带状铁建造经加里东造山期的挤压、破碎 ,隐伏花岗岩基和石英闪长岩脉侵入及与衍生成矿流体的水岩反应等作用 ,使其中的铜元素活化析出并被带到就近的有利构造空间沉淀成矿 ,其成矿年龄限定于 (36 4 .7± 8.4 )Ma～ (4 76± 15 )Ma之间。The Huashugou copper deposit is a new type copper deposit discovered recently in the Jingtieshan ore district. The copper deposit is situated in the banded iron formation of the Jingtieshan Group on the northern side of the Jingtieshan iron ore field. Its orebody is controlled strictly by the fracture_altered zone within the ore district. The deposit has both the marks of the sedimentation and the features of the later hydrothermal process. Based on an analysis of the regional background and the geological features of the deposit, the authors determined the zircon U_Pb age of the quartz diorite veins associated with the copper mineralization and the 40 Ar_ 39 Ar age of the altered sericitolite in the alterad rock_type copper ore. It is thought that the Huashugou copper deposit was formed through two processes: the enrichment of Cu in banded iron formation was completed in Proterozoic, and then Cu in the banded iron formation was mobilized by fracturing, intrusion and hydrothermal fluid and finally precipitated in fractures in Caledonian. The metallogenic age should be within the period of (364.7±8.4) Ma to (476±15) Ma.

关 键 词：甘肃 铜矿床 成矿年龄 锆石U-PB同位素年龄 氩同位素 水岩反应 成矿流体 

分 类 号：P618.41[天文地球—矿床学]