查干凹陷下白垩统烃源岩地球化学特征

下白垩统巴音戈壁组、苏红图组湖相暗色泥岩是查干凹陷发育的主要烃源岩。从有机质丰度、有机质类型、有机质成熟度以及生物标志物特征等方面研究了查干凹陷下白垩统烃源岩的地球化学特征。研究结果表明：该烃源岩有机质丰度高，整体上为较好烃源岩；有机质类型属过渡型，其中巴音戈壁组有机质类型优于苏红图组，前者以Ⅱ，一Ⅱ：型为主，后者以Ⅱ2一Ⅲ型为主；有机质热演化程度较高，均达到了成熟阶段．部分处于高成熟一过成熟阶段：该烃源岩发育于湖相弱氧化一弱还原沉积环境，有机质母质为以低等水生生物为主、高等植物为辅的混源输入。

Geochemical characteristics of hydrocarbon source rocks of the Lower Cretaceous in the Chagan Sag

Lacustrine dark mudstones of the lower Cretaceous Bayinggebi Formation and Suhongtu Formation are the main hydrocarbon source rocks in the Chagan Sag. This paper revealed the geochemical characteristics of the source rocks on the basis of the abundance, types and maturity of organic matter and biomarker analysis. The results show that hydrocarbon source rocks have high abundance of organic matter and belong to good hydrocarbon source rocks, and the type of organic matter belongs to transition type. The organic matter type of Bayinggebi Formation is superior to that of Suhongtu Formation. The former is mainly of Ⅱ1 - Ⅱ2, while the latter is mainly of Ⅱ 2 - Ⅲ. The organic matter of the hydrocarbon source rocks has a high degree of thermal evolution and is at maturity stage, even a high-post maturity stage. The hydrocarbon source rocks occurred in the weak oxidation-weak reducing environment, and the organic source material is mainly lower aquatic plants mixed with some higher plants.