金顶铅锌矿床油气地球化学特征及其成矿作用探讨

金顶铅锌矿区上三叠统三合洞组角砾状灰岩为其主要容矿岩层 ,最近在与金顶矿床共生的灰岩角砾岩、深灰色泥晶灰岩和灰色云化灰岩中发现多层稠油储层及油气包裹体。包裹体烃类地球化学研究表明存在多源性母质输入 ,油气母源类型以藻类及细菌等微生物贡献为主 ,沉积水体介质为高盐度、较强还原环境 ,源岩演化处于低成熟～成熟。铅锌金属与稠油的共生、金属硫化物的有机生物硫特征、有机质富集地区矿化强烈等均表明有机质与金属成矿存在相互作用。按照不同世代有机质与金属成矿作用机理 ,本区有机成矿以配合作用及吸附、还原作用为主 ,有机质的存在增加了铅锌离子的溶解度 ,促进了铅锌金属离子的迁移和富集 ,有利于产生铅锌金属沉淀的还原环境。

Geochemical Characteristics of Hydrocarbonearing Area Pb-Zn Ore Deposits in Jinding and Their Metallogenic Role

Heavy crude oils and hydrocarbon inclusions were discovered recently in brecciated limestones, micrite limestones and dolomitized limestones associated with lead-zinc deposits in the Jinding area. The geochemistry of hydrocarbon inclusions indicates that the source inputs are multiple and mainly derived from lower aquatic algae and bacteria. The sedimentary water medium reduces with high salinities. Maturity of hydrocarbons is between low mature to mature. The symbiosis between heavy crude oils and lead-zinc ores, organic sulfur characteristics of metallic sulfides ,and the strong mineralization in hydrocarbons enriched zones all suggest that hydrocarbons have played an important role in metal mineralization. According to the mutual influencing mechanism between hydrocarbons generated in different stages and metal mineralization, the organic mineralization in Jinding area is mainly owing to matching, absorption and reducing. Due to the existence of hydrocarbons, the solubility of Pb 2+ and Zn 2+ increase and their migration and accumulation are accelerated. Reducing environments favorable for the formation of lead-zinc deposits are produced because the hydrocarbons act as a solvent.