云南金顶铅锌矿床的有机成矿作用——来自围岩、矿石中有机质生物标志化合物的证据

    Organic mineralization in Jinding lead-zinc deposit, Yunnan, China: the evidence from biomarker of organic matter of wall rock and ores

    • 摘要: 云南金顶铅锌矿床是世界上成矿时代最新且唯一的陆相沉积岩容矿的超大型铅锌矿床。矿区存在2类有机质——原生型和迁移型,与矿石共生。生物标志化合物研究结果表明:正构烷烃碳数分布范围较宽,有2种峰型;萜烷化合物的相对丰度五环三萜烷>三环萜烷>四环萜烷;规则甾烷C27~C28~C29呈不对称V字型分布;有机质的母质来源以低等水生生源的海藻类为主,伴随有一定量的陆源高等植物组分;有机质沉积于弱氧化—弱还原环境;成矿热液的热力作用使样品遭受了一定程度的热解,部分样品还遭受了生物降解作用;生物标志物多参数对比表明有机质来源于三叠纪三合洞组碳酸盐岩地层。原生型有机质的成矿作用主要体现在对成矿金属元素的预富集上,而迁移型有机质的成矿作用主要是对成矿金属元素的活化运移。

       

      Abstract: The Jinding ore deposit is the youngest and the only giant deposit hosted in continental sedimentary rocks in the world. There are two type of organic matters: primary and migratory ones. Analyzing on the extracted soluble organic ,biomarkers of rocks and ores of jinding lead-zinc deposit shows that n-alkanes with a relatively wide range contain two highest peak. According to the relatively abundance, pentacyclic triterpane >tricyclic terpane >quartcyclic terpane. The carbon number distribution of the steranes show a slight predominance of C28. Indicates that the organic matter of ore is origin in marine alga, and there are a certain amount of plants at the same time. The organic matter was deposited in a weak oxidation-weak reduction environment, and it approaches mature stage. Some of organic matter underwent biodegradation, and all organic samples underwent a certain degree’s thermal decomposition because of the hydrothermal alteration. Contrasting the parameters of biomarkers, which indicates that they have close relationship and reveals that the organic matter in deposit came from Triassic carbonate rocks. Primary organic matters fore-enriches ore-forming elements and migratory ones can dissolve and move ore-forming elements.

       

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