塔里木盆地寒武-奥陶系烃源岩的分子地球化学特征

对塔里木盆地下古生界样品的地球化学分析表明,上奥陶统良里塔格组、中上奥陶统却尔却克群烃源岩与其他烃源岩具有明显的差异,具有低的C28甾烷、24-降胆甾烷、甲藻甾烷、甲藻三芳甾烷与伽马蜡烷含量以及高的C24四环萜烷、重排甾烷含量等特点。柯坪地区中上奥陶统萨尔干组、印干组页岩伽马蜡烷、C28甾烷相对含量与寒武系、中下奥陶统黑土凹组烃源岩具有相似性。萨尔干组、印干组烃源岩中生物标志物的绝对含量很低。柯坪地区寒武系玉尔吐斯组、中上奥陶统萨尔干组、上奥陶统印干组、满东地区中下奥陶统黑土凹组等较强沉积环境的泥质烃源岩伽马蜡烷、C28甾烷、特殊甾烷的相对含量与海相原油主体有较大差异。上奥陶统印干组烃源岩较高含量的三芳甲藻甾烷、24-降重排胆甾烷和24-降胆甾烷化合物的检出表明,断代生物标志物的提法值得商榷。

Molecular geochemical characteristics of Cambrian-Ordovician source rocks in Tarim Basin, NW China

The geochemistry analysis of the Paleozoic source rocks in the Tarim Basin shows Upper Ordovician Lianglitage Formation and Middle-Upper Ordovician Queerqueke Group, which are poor in C28 sterane, 24-norcholestane, dinosterane, triaromatic dinosterane, gammacerane and rich in C24 tetracyclic terpane, and have obvious differences in the biomarkers with other source rocks.The source rocks of Middle-Upper Ordovician Saergan Formation and Yingan Formation have similar contents of gammacerane and C28 sterane with those of the Cambrian and Lower-Middle Ordovician Heituwa Formation.The absolute concentrations of the biomarkers of Saergan Formation are very low.The relative contents of gammacerane, C28 sterane, C26 sterane and C30 sterane of the mudstones from Cambrian Yuertusi Formation, Middle-Upper Ordovician Saergan Formation, Upper Ordovician Yingan Formation in the Keping area and Lower-Middle Ordovician Heituwa Formation in the East Manjiaer Depression have obvious differences with those of the main marine oils.The detection of high contents of triaromatic dinosterane, 24-norcholestane and 24-nordiacholestane in Yingan Formation suggests the age-specific biomarker should be reconsidered.