云南大坪大型金多金属矿床叠加成矿作用:地质、流体包裹体和稳定同位素证据  

Superposed mineralization in Daping Au-Cu-Ag-Pb deposit,Yunnan province:Evidences from geology,fluid inclusions and stable isotopes

作　　者：葛良胜[1] 邓军[1] 李汉光[2] 杨立强[1] 张文钊[2] 袁士松[2] 邢俊兵[2] 

机构地区：[1]中国地质大学"地质过程与矿产资源国家重点实验室",北京100083 [2]黄金地质研究所,廊坊065000

出　　处：《岩石学报》2007年第9期2131-2143,共13页Acta Petrologica Sinica

基　　金："十一五"国家科技支撑计划"危机矿山接替资源勘查技术与示范研究"重点项目课题(2006BAB01B10)"哀牢山地区金;多金属成矿规律及找矿方法技术研究";武警黄金指挥部基金项目(HJ03-01);中国地质大学(北京)"地质过程与矿产资源"国家重点实验室基金项目GPMR200628

摘　　要：对云南元阳县大坪大型金多金属矿床矿脉地质特征、流体包裹体和稳定同位素的研究表明,矿区内大量的矿脉是叠加成矿的产物,空间上具有并置、侧列(现)、再现等复杂关系,成矿可分石英-黄铁矿(主要形成金矿化)和石英-方铅矿(主要形成铜铅银矿化,并叠加有金矿化)两个阶段共7个亚阶段。石英-黄铁矿阶段流体包裹体以个体小,数量多,杂乱分布为特征,以二相气液包裹体为主,均一温度变化区间为165℃～393℃,平均258℃;流体密度为0.648～0.7984g/cm^3,盐度变化为13.72%～18.96% NaCl eqv,平均17.13% NaCl eqv,捕获压力为64MPa 左右。流体为含 CO_2的 NaCl-H_2O 体系,在成分上相对富集 Na^+、CI^+、CH_4和 N_2、NO_3^-等组分,从早到晚,具有 Na^+、Ca^(2+)、SO_+^(2-)略有升高,而 K^+有所降低的趋势。石英方铅矿阶段流体包裹体大小混杂,杂乱分布或呈线性排列,以 CO_2包裹体为主,并有二相气液和少量单相包裹体。均一温度177℃～372℃,平均284℃,流体密度为0.7413～0.9518g/cm^3,盐度变化为10.86%～21.26% NaCl eqv,平均14.16% NaCl eqv,捕获压力为60MPa 左右。流体属为 NaCI-H_2 O-CO_2体系,在成分上以相对富集 Na^+、K^+、SO_4^(2-)为特征,部分脉体的流体包裹体中还含有一定量的 Ca^(2+)、Mg^(2+)等离子。矿区不同(亚)阶段矿石氧同位组成总体变化较小(2.65‰～6.0‰),氢同位素组成变化较大(-120‰～-40‰),其中石英-黄铁矿阶段 H、O 同位素组成变化均较小,以岩浆源为主,而石英-方铅矿阶段氢同位素组成变化较大,表明有新的流体加入,但也以深源流体为主;石英-方铅矿阶段一个铁白云石的δ^(13)C 值为-4.81‰,而石英-黄铁矿阶段晚期方解石碳同位素组成变化为-2.79‰～-4.34‰,平均-3.75‰。不同矿脉黄铁矿、方铅矿的硫同位素组成变化范围为0.3～-4.4‰,其中石英一黄铁矿阶段为0.3‰～4.4‰,石英-方铅矿阶段为0.5～4.3‰,总体上The studies on geologic characteristics and fluid inclusions and stable isotope of Daping gold deposit showed that main quartz veins were formed by superposition of at least two stages （the early quartz-pyrite stage related to the Au and the later quartz- galenate stage related to Cu, Pb, Ag and Au ） of mineralization hydrotherm. The different stage veins had complex relationships in space. The fluid inclusions of quartz-pyrite stage are characterized by fine size, big amount, disordered distribution, and mostly gasliquid facies. Their homogeneous temperatures range from 165℃ to 393℃ （ average 258 ℃ ） , fluid densities range from 0.648g/cm^3 to 0.7984g/cm^3, salinities range from 13.72% to 18.96% NaCl eqv （average 17. 13% NaC1 eqv） , pressure about 55MPa. The oreforming fluid belongs to the NaCl-H2O-CO2 system, and riches the compositions of Na^＋ , Cl^- , CH4 , N2, NO3^-. Relatively, the fluid inclusions of quartz- galenate stage are characterized by big and small intermix, disordered distributing or linear arrangement, mostly CO2 inclusions and gas-liquid facies or a few single-facies inclusions. Their homogeneous temperatures range from 177℃ to 372℃ （average 284℃ ）, fluid densities range from 0. 743g/cm^3 to 0. 9518g/cm^3, salinities range from 10. 86% to 21. 26% NaCl eqv （average 14.16% NaC1 eqv）,pressure about 60MPa. The fluid belongs to the NaCl-H2O-CO2 system, and riches the compositions of Na^＋ ,K^＋ ,SO4^2-,and some fluid inclusions in partial veins contain the compositions of Ca^2＋ ,Mg^2＋. The values of δ^18 OH2O of some inclusions of different mineralizeation stages range from 2.65‰ to 6.0‰, δD values range from - 120‰~ to -40‰ and the δ^13C value of a ankerite of quartz-galenate stage is - 4. 81‰ with the δ^13 C value of calcspar of later quartz-pyrite stage ranges from -2.79‰ to -4.34‰（average -3.75‰ ）. The δ^34S value of pyrite and galenate in different veins range from 0.3‰ to 4.4‰, thereinto, the δ^34S value of quartz-pyrite

关 键 词：流体包裹体 稳定同位素 矿脉 成矿叠加 金多金属矿床 大坪 云南 

分 类 号：P618.51[天文地球—矿床学] P597.2[天文地球—地质学]