西秦岭拉尔玛金矿热水硅质岩中的分子古生物学研究

STUDY OF MOLECULAR PALEONTOLOGY IN THERMAL CHERT IN LAERMA GOLD DEPOSIT OF WEST QINLING

拉尔玛金矿热水成因硅质岩中的分子古生物学研究表明：其正烷烃以碳数分布于Ｃ１６～Ｃ３６、主峰碳为Ｃ２９为特征；除此，还鉴定出规则类异戊二烯和胡萝卜烷系列化合物、烷基环己烷系列、长链三环萜烷、五环三萜烷、甾类分子化石和烷基噻吩系列化合物、烷基四氢噻吩系列化合物、二苯并噻吩、甲基二苯并噻吩等含硫芳烃以及菲及其同系物等非含硫芳烃分子化石．氯仿沥青“Ａ”族组成Ｑ型聚类分析表明拉尔玛金矿硅质岩与现代蓝绿藻和绿藻生物样品聚为一类，并且在增加有机硫这个参数的条件下，拉尔玛金矿硅质岩与现代陆上热泉和海底热水沉积物归为一类，这不仅说明拉尔玛金矿硅质岩的生物先体为海生低等菌藻生物，而且，有机质及分子化石是反映沉积古环境的有利指标．

Based on the molecular paleontology in thermal chert in Laerma gold deposit, this paper indicates that the molecular fossils in the chert in Laerma gold deposit include orthoalkane hydrocarbon (the carbon distributes between C 16 and C 36 and the host peak is C 29 ), regular isoprenoid hydrocarbon, carroty alkane series, alkyl cyclohenane series, long_chain tricycloterpenes, five_cyclic triterpenes, steroid, aromatic hydrocarbon bearing_sulfur (such as alkyl thiophene series, alkyl tetrahydrothiophene series, benzothiophene, methyl thionaphthene) and other aromatic hydrocarbon bearing no sulfur (include phenanthrene and its homologue). Q_mode cluster analysis of chloroform asphalt “A” shows that the chert in Laerma gold deposit gets together with the organic samples of modern cyanobacteria and green algae. In addition to organic sulfur, the cherts and the sediment of hot continental spring and sea floor are included in the same category. All the studies indicate that not only the biological mother body of the organic matter of the chert in Laerma gold deposit is primarily marine bacteria and algae but also organic matter and molecular fossils are a favorable index of sedimentary paleoenvironment.