摘要
大东沟铅锌矿是阿尔泰南缘泥盆纪克朗火山-沉积盆地的块状硫化物矿床之一,在石炭—二叠纪同造山的区域变质过程中,受到热液叠加改造作用,层状铅锌矿体发育脉状石英和矿化。本文对阿勒泰大东沟铅锌矿区石英脉中的包裹体进行了详细的岩相学和显微测温研究,估算出包裹体形成时的物理化学条件,并采用激光拉曼、同步辐射X射线荧光(SRXRF)对流体包裹体进行了成分测试。结果显示,石英脉中的包裹体主要为碳质流体包裹体,多以面状、带状分布,最低捕获温度在209～459℃之间,密度为0.75～1.15g/cm3,最低捕获压力在110～540MPa之间。初步研究表明碳质流体的来源与同造山的变质作用有关,而与海底喷流沉积无关。激光拉曼测试结果表明包裹体气液主要成分为CO2和N2。SRXRF测试碳质包裹体中金属微量元素显示低Cu、Zn、Pb,而富集Au。
The Dadonggou lead-zinc ore deposit is one of the massive sulfide deposits in the Devonian Kelan volcanic-sedimentary basin on the southern margin of the Altay Mountains. Controlled by regional Abagong-Kurti fault,the ore bodies occur in layers in the second lithologic unit of Upper Kangbutiebao Formation which consists of calcareous sandstones,biotite schists and chlorite schists.The ore minerals are sphalerite,galena and pyrite assuming massive,disseminated,banded and veinlet forms. During the regional tectonic-hydrothermal metamorphism of Carboniferous-Permian orogeny,this ore deposit experienced hydrothermal transformation,resulting in the development of veinlike quartz and mineralization. Two metallogenic stages can be identified：the first was the marine volcanic sedimentary stage,and the second was the metamorphic hydrothermal stage. There are two periods of quartz veins formed at the metamorphic hydrothermal stage：the earlier white-gray pyrite quartz veins （Q1） occur in layers and the late polymetallic sulfide quartz veins （Q2） cut the strata. By means of lithofacies observation and microthermometry,the authors carried out a detailed study of the fluid inclusions hosted by the quartz veins of the metamorphic hydrothermal stage. Combined with the preliminary findings,the authors estimated the physical and chemical conditions. Laser Raman and synchronic radiation X-ray fluorescence（SRXRF）were also used to analyze elements in the fluid inclusions. It is shown that the inclusions in the quartz veins are mainly carbonic fluid inclusions （CO2-N2±CH4） 4～37 μm in size,mostly assuming planar and ribbon distribution. There are also minor amounts of H2O-CO2 fluid inclusions associated with carbonic fluid inclusions. The experiment results of carbonic fluid inclusions show that tm,CO2（solid CO2 melting temperatures） are -82.5～ -59.4℃,th,CO2 （homogenization temperatures） are -40.2 ～20.3℃,and the lowest trapping temperatures are 209～459℃,that the densities range from 0.75 to 1.15 g/cm3,and that the estimated pressures are concentrated in the range of 110～540 MPa. The tests indicate that the gas and liquid ingredients in carbonic fluid inclusions mainly consist of CO2 and N2,and the minor elements are low in Cu,Zn,Pb but rich in Au. The environment for the formation of the carbonic fluid inclusions was basically consistent with the regional conditions of the orogenic belt,especially the biotite metamorphic belt. The tentative research suggests that the carbonic fluid inclusions were probably related to synorogenic metamorphism but had nothing to do with the submarine exhalation. The carbonates widely distributed in Lower Devonian Kangbutiebao Formation in the Kelan basin might have provided the main carbon sources for carbonic fluid inclusions.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2010年第2期175-188,共14页
Acta Petrologica et Mineralogica
基金
国家自然科学基金资助项目(40672060
40972066)
国家科技支撑计划资助项目(新疆305项目2007BAB25B01)
中国科学院高能物理研究所北京正负电子对撞机国家实验室课题(vr-08030)
关键词
碳质流体包裹体
大东沟铅锌矿
阿尔泰
变质
carbonic fluid inclusions Dadonggou lead-zinc ore deposit Altay metamorphism
作者简介
褚海霞（1984-），女，汉族，在读硕士研究生，岩石学、矿物学、矿床学专业，E—mail：chuhaixia031188@163．com；
通讯作者徐九华（1951-），男，汉族，教授，博士生导师，E-mail：jiuhuaxu@ces．ustb．edu．cn。
