东天山西滩浅成低温热液金矿床地球化学  

GEOCHEMISTRY OF THE XITAN EPITHERMAL GOLD- SILVER DEPOSIT, EAST TIANSHAN MOUNTAINS

作　　者：丰成友[1] 薛春纪 姬金生[2] 张连昌[2] 李华芹[3] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]西安工程学院,西安710054 [3]中国地质科学院宜昌地质矿产研究所,宜昌443003

出　　处：《矿床地质》2000年第4期322-329,共8页Mineral Deposits

基　　金：国家科技攻关305项目!( 85 - 90 2 - 0 5 )部分研究成果

摘　　要：对东天山西滩金矿床稀土元素地球化学、流体包裹体和 H、 O、 S、 Pb、 Sr、 C、 Si等稳定同位素组成的研究表明 ,该金矿床成矿元素来自赋矿围岩 ;成矿流体主要为大气降水 ,显示出低温、低压、低—中等盐度、弱酸—中性等特征 ;成矿作用发生在碰撞造山期 ,多期次热液叠加和幕式特征显著 ;矿床成因应属冰长石Hosted by Lower Carboniferous Aqishan Group, the Xitan gold deposit is controlled by arcuate faults related to paleo caldera. ΣREE values in this deposit decrease from wall rocks through altered rock type ores to quartz vein ores. The REE pattern of the altered rock type ores is similar to that of the wall rocks, while the partition curves of the quartz vein ores are relatively steep. Fluid inclusion studies of quartz yield homogenization temperature of 137℃ to 250℃, mainly from 150℃ to 200℃ and fluid pressure of (268～326)×10 5Pa. Salinities of primary fluid inclusions range from 0 8% to 6 7% NaCl equivalent. Isotopic geochemical studies show that δ D and δ 18 O H 2O values of the ore forming fluids are -119 to -90 per mil and -12 7 to -1 6 per mil, respectively. δ 34 S values of pyrite and whole rock vary from 0 1 to 1 3 per mil and from 1 4 to 2 3 per mil, respectively. ( 87 Sr/ 86 Sr) i values of ores and wall rock determined by Rb Sr isochron technique are very close to each other, being 0 7049 to 0 7059 and 0 7046 respectively. δ 13 C volume of calcite from the ore is -5 47 per mil, and δ 30 Si volumes of wall rock and ores are from 0 1 to 0 3 per mil. In addition, the main gold mineralization took place at (244±9)×10 6 a based on the Rb Sr isochron dating. All the REE and isotopic geochemical characteristics indicate that the ore forming substance of this gold deposit was directly derived from wall rock, the ore forming fluids were dominantly meteoric water and were characterized by low temperature, low pressure and low to medium salinity, and the ore forming process took place in collision and orogenic period, with very obvious multistage superimposition and episodic mineralization. It is concluded that the Xitan gold deposit is a kind of adularia sericite type epithermal gold silver deposit according to P Heald's classification.

关 键 词：浅成低温热液 地球化学 金矿床 流体包裹体 

分 类 号：P618.510.1[天文地球—矿床学] P59[天文地球—地质学]