新疆西天山阿希金矿床流体包裹体地球化学特征  

Geochemistry of fluid inclusions in the Axi gold deposit,West Tianshan,Xinjiang.

作　　者：张作衡[1] 毛景文[1] 王志良[1] 左国朝[2] 陈伟十[1] 朱和平[3] 王龙生[1] 吕林素[4] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]甘肃省地质调查院,兰州730000 [3]中国科学院地质与地球物理研究所,北京100029 [4]中国地质博物馆,北京100034

出　　处：《岩石学报》2007年第10期2403-2414,共12页Acta Petrologica Sinica

基　　金：国家科技支撑重点项目(编号:2006BAB07808-01);地质调查项目(1212010561603-3和1212010634001)的研究成果。

摘　　要：本文在系统总结前人关于矿床地质特征和流体成矿作用研究成果的基础上,补充开展了热液成矿期石英-碳酸盐阶段石英、方解石和重晶石中流体包裹体的均一法和冷冻法测温,并对石英样品进行了气相色谱测量,对石英流体包裹体中的稀土和微量元素进行了测试。结果表明,矿床具有典型的浅成低温热液金矿的特点,成矿流体总体上盐度很低,多数都集中于0.53～1.57wt%NaCl。成矿流体的主要成分为H_2O、CO_2和CH_4。流体包裹体微量元素与容矿围岩具有继承性,流体中Cu、Ni、Co、Mo、Zn、Pb、V、Sb和Li等的含量较高,可能说明了Cu、Zn、Co、Ni、Bi和Ba等元素在水岩反应过程中更容易进入流体当中。石英流体包裹体中∑REE为13825×10^(-12)～149935×10^(-12),LREE/HREE为2.63～50.83,δEu为0.70～0.91,表现为Eu的弱亏损。成矿流体的REE配分型式与火山岩具有相同的Eu亏损和右倾配分曲线,表明成矿流体在演化过程中可能继承了早期火山岩的REE特征;但成矿流体的LREE/HREE值比火山岩大,前者的REE配分曲线比后者更加右陡倾斜,这可能与后期变质水和大气降水的混入引起的成矿流体物质组分发生有关。Based on a systematical summing-up of the previous research on the geological characteristics and ore fluid processes of the Axi gold deposit, the authors carried out supplemental measurements of homogeneous and freezing temperatures and salinities of fluid inclusions in quartz, calcite and barite formed in the quartz-carbonate mineralization stage of the hydrothermal mineralization period, gas chromatographic analysis of quartz samples and analysis of REE and trace elements in fluid inclusion in quartz. The results show that the Axi gold deposit has the characteristics of typical epithermal gold deposits. The salinities of ore-forming fluids are in general very low, mostly clustering on 0.53 to 1.57 wt% NaCl equivalent. The ore-forming fluids are mainly composed of H, 0, CO, and CH,. The trace elements in the fluid inclusions inherited those in country rocks. The relatively high contents of trace elements such as Cu, Ni, Co, Mo, Zn, Pb, V, Sb and Li may reveal that these elements were rather easy to enter the fluids during the water-rock reaction. The Sigma REE of the fluid inclusions in quartz range from 13825 x 10(-12) to 149935 x 10(-12), and the LREE/HREE ratios vary from 2.63 to 50.83. Err displays slight depletion with delta Eu ranging from 0.70 to 0.91. The ore fluids in the fluid inclusions display the same Eu depletion and right-inclined chondrite-normalized REE distribution patterns as the host volcanic rocks of the Axi gold deposit. This may suggest that the ore fluids in the inclusions might inherit the features of REE of the early-stage volcanic rocks. However, the LREE/HREE ratios of the ore fluids are higher than those of the volcanic rocks: the BEE distribution patterns for the former are more right-inclined than those for the latter, which may be related to the change in composition of the ore-forming fluids caused by mixing of metamorphic and meteoric water in the late stage.

关 键 词：流体包裹体 地球化学 阿希金矿 新疆 

分 类 号：P618.51[天文地球—矿床学] P5[天文地球—地质学]