摘要
马坑铁矿是福建省下个大型铁钼铅锌多金属矿床,赋存于莒舟-大洋花岗岩外接触带上石炭统经畲组-下二叠统栖霞组大理岩与下石炭统林地组石英砂岩之间,矿化阶段经历了从无水矽卡岩阶段（钙铁榴石-透辉石）→含水矽卡岩-磁铁矿阶段（绿帘石-阳起石-绿泥石-钙铁辉石）→硫化物阶段（石英-方解石-萤石-黄铁矿-闪锌矿）→碳酸盐岩阶段（石英-方解石）演变,而本文对含水矽卡岩-磁铁矿阶段和硫化物阶段中的钙铁辉石、萤石、石英及方解石中流体包裹体所进行岩相学观察和显微测温研究表明,早期含水矽卡岩-磁铁矿阶段包裹体类型主要有含NaCl子晶三相包裹体和富液相两相包裹体,少量富气相两相包裹体;而晚期硫化物阶段包裹体类型主要为富液相两相包裹体.含水矽卡岩-磁铁矿阶段流体出现流体沸腾作用,流体温度范围为448-596℃,两端员组分流体盐度分别为26.5-48.4 wt%NaCl equiv.和2.4-6.9 wt%NaCl equiv.;硫化物阶段流体呈现出混合趋势,流体温度和盐度分别为182-343℃和1.9-20.1 wt%NaCl equiv..流体包裹体的均一温度和盐度的研究结果表明含水矽卡岩-磁铁矿阶段流体主要来自岩浆水,而硫化物阶段流体以岩浆水为主,并有大气降水加入.由于马坑铁矿化形成于含水矽卡岩阶段,铅锌矿化则形成于硫化物阶段,流体沸腾是导致马坑铁矿床形成的主要因素,而流体混合则是引起马坑铁矿床铅锌矿化的主要因素.综合地质与地球化学研究,马坑铁矿床应属于与莒舟-大洋花岗岩有关的矽卡岩型铁矿床.
Makeng iron deposit is a large scale Fe-Mo-Pb-Zn polymentallic deposit in Fujian province hosted in the external contact
zone of Juzhou-Dayang granites between the Jingshe Formation-Qixia Formation marbles and the Lindi Formation quartz sandstones.Mineralization stages can be classified into four stages： （1） anhydrous skarn stage （andradite-diopside）; （2） hydrous skarn-magnetite （epdiote-chlorite-actinolite-hedenbergite）;（3）sulfidesstage（quartz-calcite-fluorite-sphalerite-galena）;（4）carbonatesstage（quartz-calcite）.Petrographic and microthermometric studies of fluid inclusions in hedenbergite, fluorite, quartz and calcite of different mineralization stages show that the fluid inclusions related to magnetite mineralization are dominated by daughter mineral-bearing fluid inclusions,liquid-rich aqueous fluid inclusions, and minor vapor-rich fluid inclusions; fluid inclusions in sulfide mineralization stage mainlyinclude liquid-rich aqueous fluid inclusions. Ore fluid in iron oxide stage evidence for boiling at the temperature range of 448 to 596℃, with salinities of 26.5 to 48.4 wt % NaCl equiv. for one end member fluid and 2.4 to 6.9 wt % NaCl equiv. for the other end member fluid. Whereas ore-forming fluid in sulfide stage exhibits a mixing trend, with the temperature and salinity of 182 to 343℃ and 1.9 to 20.1 wt % NaCl equiv., respectively. Based on the fluid-inclusion data, early-stage magnetite mineralization fluids were originated mainly from magmatic water, and late-stage sulfide mineralization fluids were derived from mixtures of magmatic water and meteoric water. Because Fe mineralization was formed in the hydrous skarn stage and Pb-Zn mineralization was formed in the sulfide stage, the early-stage magnetite deposition may have resulted from fluid boiling and the late-stage sulfide deposition may have contributed to fluid mixing between magmatic water and meteoric water. Overall, the Makeng deposit is interpreted as a skarn type Fe-Mo-Pb-Zn polymentallic deposit related to intermediate-acid pluton based on skarn mineralogy and fluid inclusion characteristics.
出处
《高校地质学报》
CAS
CSCD
北大核心
2016年第3期401-412,共12页
Geological Journal of China Universities
基金
国家重点研发计划(2016YFC0600205)
关键词
莒舟-大洋花岗岩
流体包裹体
流体沸腾
马坑铁矿
福建
Juzhou-Dayang granites
fluid inclusion
fluid boiling
Makeng deposit
Fujian Province
