阿姆河盆地侏罗系海相烃源岩地化特征及与中国海相烃源岩比较

阿姆河盆地上侏罗统海相烃源岩是一套公认的成熟烃源岩,其成熟度与中国古生界高-过成熟度海相烃源岩不同,通过对阿姆河右岸地区上侏罗统岩石样品的地球化学分析及与中国塔里木和华北、四川、吐哈、渤海湾等盆地类似烃源岩的比对,研究了阿姆河盆地成熟海相烃源岩地化特征,建立了有机质丰度与类型的评价标准与图版。结果表明:阿姆河盆地侏罗系存在灰岩和泥岩两类海相烃源岩,灰岩有机质丰度略高于塔里木盆地古生界和华北地台中上元古界灰岩,与四川盆地二叠系灰岩接近,泥岩有机质丰度与吐哈盆地侏罗系煤系泥岩相当,成倍好于塔里木盆地、华北地台海相泥岩;海相泥岩属于Ⅰ₂~Ⅱ型烃源岩,海相灰岩属于Ⅲ~Ⅱ型烃源岩,综合分析认为:1）阿姆河盆地上侏罗统灰岩好烃源岩有机碳含量标准为0.5%,泥岩好烃源岩有机碳含量标准为3%;2）以低等生物为主的海相碳酸盐岩或泥岩,其可溶有机质氯仿沥青“A”族组分、Pr/Ph与Ph/nC₁₈关系、甾烷ααα（C₂₇、C₂₈、C₂₉）-20R含量、多环芳香“三芴”系列等参数既揭示了烃源岩的生源环境,也是鉴别母质类型的良好参数。阿姆河盆地上侏罗统海相泥岩和灰岩烃源岩评价标准与图版的建立,对国外海相盆地油气资源评价具有重要意义。

Geochemical Characteristics of Jurassic Marine Source Rock in Amu Darya Basin and Comparison with Marine Source Rocks in China

Upper Jurassic marine source rocks in Amu Darya Basin are a set of generally accepted mature source rocks, and the maturity of them show difference against Paleozoic high-over maturity marine source rock in China.Through geochemical analyses of upper Jurassic rock samples in right bank of Amu Darya Basin and contrast among similar source rocks from basins of China Tarim, Huabei, Turpan-Hami, Bohai Gulf, we examine mature marine source rocks in Amu Darya Basin and build evaluation standard and charts of organic matter abundance and types.The results show that there are two types of Jurassic mature marine source rocks in Amu Darya Basin: limestone and mudstone, and the organic matter abundance of limestone is slightly higher than the Paleozoic limestone in Tarim Basin and middle-upper proterozoic limestone in North China Platform, and is close to the Permian limestone in Sichuan, while the organic carbon of mudstone is equal to that of Jurassic mudstone in coal-measures and is much better than the marine mudstone in Tarim Basin and North China Platform;marine mudstone belongs to type Ⅰ2~Ⅱsource rock while marine limestone belongs to type Ⅲ~Ⅱ source rock.Comprehensive analyses show that ①upper Jurassic marine limestone belongs to middle class source rock while marine mudstone belongs to good source rock, and the TOC standard value is 0.5% and 3% respectively;②parameters like resolvable chloroform asphalt "A" constituents, relation between Pr/Ph and Ph/nC18、polycyclic aromatics "benzfhiore tri-fluorene" of marine carbonate rock or mudstone major in lower eukaryote not only discover the generation environment of source rocks, but also are good parameters to distinguish types of mother matter.The build of evaluation standard and charts of upper Jurassic marine mudstone and limestone in Amu Darya Basin have great significance on overseas marine basins hydrocarbon resources assessment.