广西五圩矿田箭猪坡铅锌矿床流体包裹体特征及其地质意义

Characteristics of fluid inclusions of Jianzhupo Pb-Zn deposit in Wuxu ore field of Guangxi and its geological significance

箭猪坡铅锌锑多金属矿床是桂西北丹池成矿带南段五圩矿田中规模最大、特征最为典型的一个大型矿床。根据野外地质调查及岩相学观察,将区内成矿分为三个成矿阶段,并对主成矿阶段的石英、方解石及闪锌矿中流体包裹体进行了研究。箭猪坡矿床流体包裹体类型主要有H_2O-NaCl型、H_2ONaCl-CO_2型和纯CO_2型。显微测温实验结果表明:两相H_2O-NaCl型包裹体均一温度为113℃~288℃,主要分布范围160℃~200℃,盐度w(NaCl)为3.53%~8.27%,主要集中于4.0%~6.0%,密度为0.799~0.996g/cm3;H_2O-NaCl-CO_2型包裹体均一温度为175℃~328℃,主要分布范围260℃~320℃,盐度w(NaCl)为0.21%~11.84%,主要集中于4.0%~7.0%,密度为0.654~0.842g/cm^3,成矿流体的捕获压力为46.5~99.7MPa,换算成矿深度为1.75~3.77km。依据流体盐度和温度空间分布变化规律并结合区内构造地质特征研究认为,箭猪坡矿床成矿流体由北边深部向南部运移,矿体向北侧伏,矿区中段背斜拐弯部位及北段的深部为今后找矿方向。

Jianzhupo Pb-Zn-Sb polymetallic deposit is the largest deposit with the most typical characteristics in Wuxu ore field in south section of Danchi metallogenic belt in northwest Guangxi.Based on the results of field geological investigation and petrographic observation,the mineralization of this area can be divided into three metallogenic stages.This paper conducted analysis on the fluid inclusions in quartz,calcite and sphale-rite of the main mineralization stage.The types of fluid inclusions of Jianzhupo deposit include H 2 O-NaCl type,H 2 O-NaCl-CO 2 type and pure CO 2 type.The results of microthermometry test indicated that:the homogeneous temperature of two-phase H 2 O-NaCl type inclusions ranged from 1 13℃ to 288℃ with the main distribution range of 1 60℃~200℃,and the salinity w (NaCl)ranged from 3.53% to 8.27% with main dis-tribution range of 4.0%~6.0%,and the density ranged from 0.799 g/cm3 to 0.996 g/cm3 ;the homogeneous temperature of H 2 O-NaCl-CO 2 type inclusions ranged from 175℃~328℃ with the main distribution range of 260℃~320℃,and the salinity w (NaCl)ranged from 0.21% to 1 1.84% with main distribution range of 4.0%~7.0%,and the density ranged from 0.654~0.842 g/cm3 .The trapping pressure of ore-forming fluid ranged from 46.5 MPa to 99.7MPa,and through conversion it can be estimated that the depth of mineraliza-tion is 1.75~3.77km.Based on the study on the change law of spatial distribution of salinity and tempera-ture of the fluid,and combined with the research of the geological features of structures in this area,the au-thor believed thatthe ore-forming fluid of Jianzhupo deposit migrated from the deep part of the north side to the south side and the ore body pitched northward.It is indicated that the turning part of anticline of the middle section and the deep part of the north section of the mining area are prospecting targets in the future.