西秦岭造山带硅质岩的成岩成矿演化特征——以八方山-二里河矿区赋矿硅质岩为例  

Diagenesis and Metallogenesis Evolution of Chert in West Qinling Orogenic Belt:A Case from Bafangshan-Erlihe Pb-Zn Ore Deposit

作　　者：李红中[1,2,3] 周永章[1,2,3] 杨志军[2,3] 周国富[1] 何俊国[2,3] 马占武[2,3] 吕文超[2,3] 李文[2,3] 梁锦[2,3] 卢文姬[2,3] 

机构地区：[1]中国科学院地球化学研究所/矿床地球化学国家重点实验室,贵阳550002 [2]广东省地质过程与矿产资源探查重点实验室,广州510275 [3]中山大学地球科学系,广州510275

出　　处：《吉林大学学报（地球科学版）》2011年第3期715-723,共9页Journal of Jilin University：Earth Science Edition

基　　金：国家'973'计划项目(2006CB403508);国家自然科学基金项目(40573019);矿床地球化学国家重点实验室开放基金项目

摘　　要：硅质岩是一类广泛分布于造山带内的岩石,其组成简单且具有较高的稳定性。然而,硅质岩的这种高稳定性是宏观的,在微观上仍然会保留地质演化和成岩过程的痕迹,可以从中提取造山带演化过程中的温度、压力和流体等重要信息。秦岭造山带西段八方山-二里河Pb-Zn矿区的赋矿硅质岩的光学显微镜、激光拉曼(RAMAN)、X射线粉晶衍射(XRD)和扫描电镜-能谱(SEM-EDS)研究结果表明,该硅质岩明显受到了造山作用、成矿作用和重结晶作用等的改造。显微镜下,硅质岩主要由细-微晶石英和少量的碳酸盐矿物(方解石、白云石等)组成,微裂隙和脉体的存在反映其曾经受到张应力作用,而微褶皱以及矿物的定向排列则说明其受到压应力的影响。XRD和SEM分析也指示其遭受了压应力作用。RAMAN原位微区分析结果揭示了石英的重结晶作用及其受流体的影响。硅质岩的SEM图片中金属硫化物的线状和浸染分布可能与温度、压力和流体等对硅质岩进行了不同程度的改造有关。The chert,with simple component and high stability,is widely distributed in orogenic area.It＇s stable in macroscopic traces,however,such traces showing geological evolution and diagenic metamorphism of large scale orogeny can be found by the microfabric study,as temperature,pressure and fluids.The ore-hosting chert from Bafangshan-Erlihe Pb-Zn ore deposit is studied by optical microscope,RAMAN,XRD and SEM-EDS.It is indicated that the chert was of obvious alteration during the orogeny,metallogenesis and recrystallization.Under microscope,the chert is composed of cryptomere-minicrystal quartz and carbonate minerals（calcite,dolomite and etc.） and is altered by different stresses.Tiny fissures and veins result from extensional stress,while the tiny fold and oriented arrange of the minerals indicate the effect of compressive stress.Moreover,the effect of compressive stress is also confirmed by the shortening of crystallographic axis for quartz of XRD analysis and oriented carbonate minerals under SEM.In the RAMAN analysis,the crystallinity of quartz grain decrease from the center to the edge,while the crystallinity increase sharply at the edge between quartz and carbonate veins,indicating that the upper fluids accelerating the recrystallization of the quartz grain.Under SEM,the metal sulphides distributed as linear and disseminated structures,probable are caused by the alteration of temperature,stress and fluids.Under a certain temperature and pressure,the chert are deformed,producing oriented mineral（carbonate minerals）,which provide transportation and deposition space for the ore-forming fluids.

关 键 词：秦岭 造山带 Pb-Zn矿 微组构 硅质岩 

分 类 号：P618.4[天文地球—矿床学]