桂中盘龙铅锌矿流体包裹体特征及其对钦杭成矿带热水喷流-改造成矿作用的指示

发布时间：2018-05-04 06:42

  本文选题：钦杭成矿带 + 盘龙铅锌矿　； 参考：《岩石学报》2017年03期

【摘要】：盘龙铅锌矿是近年来在钦杭成矿带南段新发现的大型铅锌矿床,位于广西大瑶山西侧,属于桂中坳陷带与大瑶山隆起的结合部位。它的容矿围岩为泥盆纪上伦组白云岩。成矿过程可分为三个成矿期:1)原生沉积期,以星散状构造、似层状-条带状构造、浸染状构造、胶状-变胶状构造、草莓状构造、揉皱构造等矿石组构特征为代表;2)活化改造期,成矿元素重新活化富集形成网脉状构造、假角砾状构造、环带构造、晶洞构造、小球状构造、交代结构、压力结构等;3)地表氧化期,原生的硫化物在地表被氧化。本研究系统分析了原生沉积期和活化改造期重晶石内的流体包裹体特征。包裹体岩相学分析显示,两个期次的流体包裹体类型均比较简单,主要为富液相的气液两相包裹体。显微测温结果显示,原生沉积期均一温度范围110.0~234.3℃(平均值为147℃),盐度介于0.33%~15.57%NaCleqv之间(均值为7.09%Nacleqv)。活化改造期均一温度稍低于原生沉积期,但盐度却明显高于前者,均一温度范围107.9~179.5℃(平均值为139℃),盐度范围1.81%~21.24%NaCleqv(均值为10.90%Nacleqv)。拉曼分析测试显示,两个成矿期次流体包裹体气相组分主要为H_2O。原生沉积期和活化改造期成矿流体均具有中低温、低盐度和贫CO_2的特征。结合重晶石矿物的产出状态,原生沉积期流体特征与SEDEX型矿床流体特征相吻合,而对其改造的后期流体与浅成低温热液矿床或者SEDEX型矿床流体特征相符。联系到区域演化历史及海底热水的幕式喷发特征,本研究认为,盘龙铅锌矿是典型的古生代热水喷流沉积叠加后期改造成矿的复合"二阶段成矿作用"的结果,对古生代地层中SEDEX型矿床的改造动力来源于后期浅成低温热液活动,也可能是晚期的又一次热水喷流活动。
[Abstract]:Panlong Pb-Zn deposit is a large Pb-Zn deposit newly discovered in the southern section of Qinghang metallogenic belt in recent years. It is located on the west side of Dayaoshan in Guangxi and belongs to the combination of Guizhong depression and Dayaoshan uplift. Its ore-bearing surrounding rock is dolomite of Devonian Shanglun formation. The metallogenic process can be divided into three metallogenic stages: 1) primary depositional stage, with scattered structure, lamina-banded structure, disseminated structure, glue-metamorphic structure, strawberry structure, and so on. The ore-fabric characteristics such as crinkle structure and so on are characterized by the activation and transformation of ore-forming elements, the reactivation and enrichment of ore-forming elements into net-vein structure, pseudo-breccia structure, annular structure, crystal cavity structure, small globular structure, metasomatic structure, etc. Pressure structure et al. (3) during the surface oxidation period, primary sulphides are oxidized on the surface. The characteristics of fluid inclusions in barite during primary deposition and activation transformation are systematically analyzed in this study. The petrographic analysis of inclusions shows that the types of fluid inclusions in the two stages are relatively simple, mainly gas-liquid two-phase inclusions rich in liquid phase. The results of microthermometry show that the homogenization temperature range of primary deposition period is 110.0 ~ 234.3 鈩，

本文编号：1842004