晚白垩世全球大规模海侵被认为仅淹没了非洲大陆北部地区,而位于非洲中部的Muglad盆地则未遭受海侵的影响,且盆地内仅发育一套富有机质的烃源岩,即下白垩统Abu Gabra组湖相泥岩。本次研究采集了下白垩统Abu Gabra组湖相泥岩和上白垩统Darfur群泥岩样品,在上白垩统Darfur群泥岩中检测到完全不同于下白垩统Abu Gabra组湖相泥岩的甲藻甾烷和三环萜烷组成,主要表现为高丰度的甲藻甾烷异构体和C₂₃三环萜烷丰度优势,认为其是海侵作用的产物。依据分析结果,本文首次提出上白垩统Darfur群沉积期可能受到新特提斯洋海水的影响,进一步揭示了晚白垩世全球海侵在非洲大陆的海水淹没范围已抵达中非大陆Muglad盆地。此外,上白垩统Darfur群海相富有机质泥岩的存在,揭示研究区不仅发育下白垩统Abu Gabra组湖相烃源岩,还发育一套潜在的海相烃源岩。而K-1井海相原油的发现进一步证实了上白垩统Darfur群海相烃源岩的生烃潜力,海相原油可能是研究区未来油气勘探的新领域。

The global transgression during the Late Cretaceous was previously believed to have primarily affected the northern African continent, with the Muglad Basin in the central African region thought to have been unaffected by this event. Within the basin, only one set of organic-rich source rock was known to have formed, namely the lacustrine mudstone of the Lower Cretaceous Abu Gabra Formation. This study collected mudstone samples from both the Upper Cretaceous Darfur Group and the Lower Cretaceous Abu Gabra Formation. Analysis revealed that the mudstones from the Upper Cretaceous Darfur Group exhibit a distinct distribution of dinosteranes and tricyclic terpanes compared to the lacustrine source rocks of the Lower Cretaceous Abu Gabra Formation, showing an abundance of dinosteranes and C₂₃ tricyclic terpanes, which are likely products of transgression. This study suggests that the mudstones from the Upper Cretaceous Darfur Group were influenced by seawater from the Neo-Tethys Ocean, indicating that the global transgression in the Late Cretaceous extended into the Muglad Basin in Central Africa. Furthermore, the presence of organic-rich marine mudstones in the Darfur Group suggests that the basin not only accumulated the lacustrine source rock of the Abu Gabra Formation but also potentially deposited a set of marine source rock. The discovery of marine oil in the K-1 well further confirms the hydrocarbon generation potential of marine source rock in the Darfur Group, pointing to new prospects for petroleum exploration in the Muglad Basin in the future.