新疆阿尔泰小土尔根铜矿床硫化物微量元素、S—Pb同位素特征及地质意义  

Characteristics of Trace Elements and S—Pb Isotope Composition of Sulfides in Xiaotuergen Copper Deposit,Altay,Xinjiang,and its Geological Implications

作　　者：樊献科 董永观[2] 秦纪华 张传林[2] 姚春彦[2] 沈雪华[2] 

机构地区：[1]中国地质科学院,北京100037 [2]国土资源部南京地质矿产研究所,南京210016 [3]新疆地矿局第四地质大队,新疆阿勒泰836500

出　　处：《地质论评》2016年第2期472-490,共19页Geological Review

基　　金：国家305项目专题"阿尔泰重要成矿带成矿动力学背景和成矿过程研究"(编号:2011BAB06B03-01)的成果~~

摘　　要：诺尔特地区位于我国重要的阿尔泰有色金属和贵金属成矿带北部山区,近年来在该区不断发现有铜金矿化点,显示该区具有较好的找矿潜力。小土尔根铜矿位于诺尔特Au—Pb—Zn(—W—Mo)成矿带北部,红山嘴大断裂的北侧,成矿条件有利。本文通过详细的野外地质考察,选取该矿不同矿体中矿石的金属硫化物进行矿物学特征研究,在此基础上测试其化学成分和S、Pb同位素组成,以探讨其成矿物质的来源和成因类型。电子探针分析表明:黄铁矿的Co/Ni比值集中分布于5.0～11.1,S/Se范围为2217～7388,指示其为与火山作用有关的潜火山热液成因;闪锌矿中S/(Zn+Fe)值高于理论值,显示了硫逸度较高的热液环境;黄铜矿的[n(Cu)+n(Fe)]/n(S)=0.98,推测其成矿温度约为200℃,这与金属硫化物阶段石英脉中所测流体包裹体的均一温度220～250℃基本一致,均表明其形成于中低温环境;方铅矿的Pb/S值低于理论值,同样指示了硫逸度较高的热液环境;闪锌矿等硫化物中,多种元素均有类质同像现象的发生。硫化物的δ^(34)S_(V-CDT)组成范围比较窄,变化范围为7.1‰～10.6‰,集中分布于7‰～9‰之间,具有较明显的塔式分布特征,主要为单一的岩浆硫。硫化物Pb同位素组成比较稳定,在铅同位素构造模式图以及△β—△γ图解中,均显示其为壳幔混合源。综合目前研究,笔者认为小土尔根铜矿可能是晚古生代早期(D_1—D_2)阿尔泰造山暂歇拉张期岩石圈伸展作用的产物。Objectives： The Nurt area is located in the northern mountainous area of Altay region which is an important metallogenic belt of nonferrous metals and precious metals in China. In recent years, many copper--gold mineralization occurences were discovered in the Nurt area, showing that it has good prospecting potential. The Xiaotuergen Copper deposit lies in the northern side of Nurt Au-Pb-Zn （-W-Mo） metallogenic belt. It also occurs at the north side of Hongshanzui fracture and has good ore-forming conditions. Very few work has been done on this deposit, we analyse the chemical composition and S--Pb isotopic composition of metal sulfides in order to study sources of ore-forming material and the metallogenesis of Xiaotuergen Copper Deposit. Methods： On the basis of detailed geological fieldwork, we selected the main metal sulfides in different parts of the deposit to study the mineralogical features and analyze their chemical composition as well as S--Pb isotopic composition, so as to trace and investigate the sources of ore-forming metal materials and its mechanism. In order to study the ore-forming temperature, we also measure the micro temperature of quartz veins which are close related to metallization. Results ： Electron microprobe analysis shows that Co/Ni and S/Se in pyrite are 5.0 - 11.1 and 2217 - 7388, suggesting the pyrite is subvolcanic hydrothermal genesis which is related to volcano effect; the mass ratios of S/（ Zn ＋ Fe） in sphalerite are higher than its theoretical values, suggesting the hydrothermal environment of relatively high sulfur fugacity ; the ratios of [ n （Cu） ＋ n （ Fe ） ]/n （ S ） is 0. 98, which infers the ore-forming temperature is approximately 200℃. This is consistent with the homogenization temperature 220 -250℃ measured in flow inclusions of quartz veins in the stage of metal sulfides, which indicates they formed in middle-low temperature environment; the mass ratios of Pb/S in galena also suggests the hydrothermal environment of relatively high sul

关 键 词：阿尔泰 小土尔根铜矿 矿石矿物 电子探针 S—Pb同位素 成矿物质来源 

分 类 号：P618.41[天文地球—矿床学] P597[天文地球—地质学]