兰坪金顶跑马坪铅锌矿床幕式流体混合成矿作用——矿石组构证据

发布时间：2018-06-25 09:52

本文选题：地质学 + 矿石组构　；参考：《矿床地质》2017年02期

【摘要】：滇西北金顶巨型Zn-Pb矿田产于兰坪晚中生代—新生代盆地中北部,对其成矿作用机制仍存在分歧。跑马坪铅锌矿床是其北东部的一个大型隐伏矿床,由众多规模不等、呈筒柱状、大脉状及不规则囊状的矿体(群)组成。大量的地质填图及坑道观察表明,该矿床的形成严格受北西向逆断层破碎带的控制,矿体就位于云龙组(Ey)砂泥岩不整合面下伏的三合洞组(T3s)碎裂状灰岩、砂结灰岩质角砾岩内;断层破碎带中的矿化更强,而旁侧的次级裂隙多被砖红色砂泥岩充填。依据矿物组合及矿石组构特点,自矿体中心向外,依次可分为致密块状富锌矿带、脉状细粒硫化物矿化带、脉状胶粒状硫化物矿化带、方解石-天青石-铁氧化物矿化带和碳酸盐化带5个矿化带,各带之间多为渐变过渡关系。显微镜、扫描电镜观测和能谱面扫描分析发现,矿石中存在代表流体混合成矿特征的环-胶状构造及包含结构等显微组构,指示富含金属离子及硫酸盐的卤水与富含还原性硫的流体在高渗透性碎裂状灰岩或灰岩质角砾岩中混合而快速沉淀成矿。因此,逆断层控制的幕式流体混合作用可能是跑马坪铅锌矿床的重要成矿机制。
[Abstract]:The Jinding giant Zn-Pb ore field in northwestern Yunnan is located in the central and northern part of the late Mesozoic and Cenozoic basins in Lanping, and there are still differences on its metallogenic mechanism. The Pb-Zn deposit is a large concealed ore deposit in the north and east of the province, which is composed of many ore bodies (groups) with different sizes, such as tubular columnar, large vein and irregular cysts. A large number of geological maps and tunnel observations show that the formation of the deposit is strictly controlled by the NW reverse fault fracture zone, and the orebody is located in the fractured limestone and sandy limestone breccia of the Sanhedong formation (T3s) under the unconformity surface of the sand and mudstone of Yunlong formation (Ey). The mineralization in fault fracture zone is stronger, while the secondary fissure on the side is mostly filled with brick red sand and mudstone. According to the mineral assemblage and the characteristics of ore fabric, the ore body can be divided into dense block zinc-rich ore belt, vein-shaped fine-grained sulfide mineralization zone, vein-shaped colloidal granular sulphide mineralization zone. Calcite-celestite-iron oxide mineralization zone and carbonation zone of 5 mineralization zones, the relationship between each belt is mostly gradual transition. Microscope, SEM observation and energy spectrum scanning analysis show that there are some microstructures, such as ring-glue structure and inclusion structure, which represent the characteristics of fluid mixing and metallogenesis in the ore. The results indicate that the brine rich in metal ions and sulfate and the fluid rich in reducing sulfur are mixed in high permeability cataclastic limestone or limestone breccia and precipitated rapidly. Therefore, the episodic fluid mixing controlled by the reverse fault may be an important metallogenic mechanism of the Paramaping Pb-Zn deposit.
【作者单位】：昆明理工大学地球科学系;中国地质科学院地质研究所;云南金鼎锌业有限公司;
【基金】：国家重点研发计划“深地资源勘查开采”专项“青藏高原碰撞造山成矿系统深部结构与成矿过程”课题(编号:2016YFC0600306-6) 国家自然科学基金项目(编号:U0933605;41373049;41302073) 中国地质调查局地质调查项目(编号:1212011121065;12120114064302;1212011020000150011) 教育部博士点基金项目(编号:20125314110006)的联合资助
【分类号】：P618.4

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