小赛什腾山斑岩铜(钼)矿床根部带的特征  

The Root Part of the Xiaosaishitengshan Porphyry Cu (Mo) Deposit

作　　者：李大新[1] 张德全[1] 崔艳合[1] 丰成友[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037

出　　处：《地球学报》2003年第3期211-218,共8页Acta Geoscientica Sinica

基　　金：国土资源部"九五"资源与环境科技攻关项目 ( 95- 0 2- 0 0 5 );地质大调查项目 (K1.1.3 .1)部分研究成果。

摘　　要：小赛什腾山斑岩型铜矿床产于柴北缘造山带之西端 ,NW向柴北缘深断裂和NEE向阿尔金深断裂分别从其旁侧通过 ,这两条深断裂的交汇部位是该矿床含铜斑岩的控岩构造。印支期花岗闪长斑岩呈岩墙状侵位于晚加里东期层状杂岩体的闪长岩相中 ,环绕该斑岩体发育有斑岩型Cu(Mo)矿化及钾硅酸盐化 绢英岩化 青磐岩化蚀变 ,这些蚀变以斑岩为中心 ,由内向外依次形成相应的面型蚀变分带。流体包裹体以液相包裹体为主要类型及高温 高盐度为基本特征 ,其中 ,在钾硅酸盐化蚀变岩内分布有含盐度达 4 8%的含NaCl子晶多相包裹体 ,均一温度变化于 5 0 0～ 6 0 0℃之间 ,测压显示其成矿深度约在 1～1.8km ,表明该含铜斑岩成矿系统形成于典型的高位、浅成环境。同位素测年结果确认 ,斑岩铜矿化形成于 2 18.5± 3.5 9Ma。详细的研究与对比认为 ,小赛什腾山铜矿床具有国内斑岩铜 (钼 )矿体系根部带的特征。The Xiaosaishitengshan porphyry Cu (Mo) deposit is located at the west end of the North Qaidam orogen and also on the NW-trending North Qaidam fault and the NNE-trending Altyn Tagh fault. The intersection of the two faults controlled the intrusion of the Cu (Mo) porphyry. The Late Triassic granodiorite porphyry, in the form of dikes, intruded into the late Caledonian dioritic complex. Cu (Mo) mineralization and hydrothermal alteration were developed around the granodiorite porphyry. The alteration zonation consists of a peripheral propylitization zone, a central potassic alteration zone and a sericitization zone which is superimposed upon the first two zones. The fluid inclusions in potassic alteration zone are characterized by coexisting three types of fluid inclusions,namely aqueous, halite-bearing and gas-rich types. Homogenization temperatures of these inclusions range from 500 ℃ to 643 ℃, with the highest salinity up to 48 wt%NaCl. These data suggest a magmatic origin and boiling process of the fluid for potassic alteration and mineralization. The estimated ore-forming depth and age are 1～1.8 km and 218.5±3.59 Ma, respectively, indicating that the Cu (Mo) porphyry was formed in a high and hypabyssal environment during the late stage of late Variscan-Indosinian orogeny in this region. A detailed comparative study shows that the Xiaosaishitengshan deposit is the root zone of an eroded Cu (Mo) porphyry.

关 键 词：斑岩型铜矿床 控岩构造 流体包裹体 同位素测年 阿尔金断裂带 成矿系统 

分 类 号：P618.41[天文地球—矿床学]