南京栖霞山多金属矿床的有机成矿作用

ORGANIC ORE FORMING PROCESS IN THE QIXIASHAN POLYMETALLIC DEPOSIT,NANJING CITY, JIANGSU PROVINCE

通过检测南京栖霞山多金属矿床成矿流体中的系列生物标志化合物，确证了成矿流体中的有机质源于赋矿地层中的菌藻类生物。成矿流体中的有机质富含有较多的杂原子，流体中的Ｚｎ含量高达２００．４×１０－６，表明成矿元素能以有机－金属络合物的形式搬运。矿石中的Ｐｂ、Ｚｎ总量与Ｓ／Ｃ比值存在一定关系，有机质通过还原ＳＯ２－４而为矿质沉淀提供Ｓ２－。并由此提出长江中下游地区许多矿床赋存于石炭－三叠系中与有机质、有机流体的这些成矿作用有一定的关系。

Biomineralization evolves coincidently with other geological processes.Many geologists have already discussed the participation of organisms in the ore forming process of the Qixiashan polymetallic deposit,and this paper deals emphatically with the role of organic matter and organic fluids in metallogenesis.Combined the non destrucive analytical techniques like optical analysis and ultraviolet fluorescent and infrared spectroscopy with the destructive techniques such as gas chromatography and gas chromatography mass sepctrography,this paper has systematically studied hydrocarbon inclusions discovered in the ore deposit,detected series of biomarkers in the ore forming fluids,and compared the difference in extractable organic matter among host rocks,ores and inclusions.Characteristics of organic matter in fluids and relationships of ore forming elements to organic carbon and sulfur show that some ore forming elements were transported by organometallic complexes and that organic fluids provided S 2- for the precipitation of metals.On such a basis,some ore forming processes of the stratabound polymetallic deposits in the middle and lower reaches of the Yangtze River are discussed.