下刚果盆地M区块Madingo组烃源岩的岩相特征与有机质富集机制

发布时间：2018-06-30 00:44

本文选题：烃源岩 + 岩相　；参考：《海洋地质与第四纪地质》2017年03期

【摘要】：以下刚果盆地M区块Madingo组烃源岩为研究对象,通过X-射线衍射、薄片鉴定、背散射、能谱分析、主量元素及有机地化测试等技术手段,分析了烃源岩的矿物组成、古生物与岩相特征,并讨论了烃源岩有机质富集机制。结果表明:Madingo组烃源岩矿物组成以黏土矿物和硅质矿物为主,方解石和长石次之,含有少量的白云石和黄铁矿;有孔虫、放射虫等微古生物发育;根据矿物组成、古生物特征和磷酸盐含量,并结合显微岩石构造,共识别出富有孔虫细粒岩、富放射虫细粒岩、磷质细粒岩、黏土质细粒岩、长英质细粒岩和灰质细粒岩6种岩相类型。研究区Madingo组烃源岩的发育受海平面升降、上升流、古地理和古气候的控制:Madingo组共识别出3期海侵/海退旋回,海平面升降通过控制水体深度、氧化还原条件和沉积物类型,进而控制岩相和烃源岩的发育;富放射虫细粒岩、磷质细粒岩和富有孔虫细粒岩有机质含量较高,推测为两期不同规模的上升流沉积;Madingo组沉积时期,研究区发育与盐底辟活动相关的陆架内部洼陷,相对封闭的水体环境有利于有机质的保存;古气候经历了干旱气候、相对湿润气候和湿润气候3个阶段,通过控制海洋中陆源有机质输入在一定程度上影响烃源岩有机质丰度和有机质类型。
[Abstract]:The source rocks of Madingo formation in M block of Congo Basin are studied. The mineral composition of the source rocks is analyzed by means of X-ray diffraction, slice identification, backscattering, energy spectrum analysis, principal elements and organic geochemistry testing. The characteristics of paleontology and lithofacies, and the enrichment mechanism of organic matter in source rocks are discussed. The results show that the mineral composition of the source rocks of the W Madingo formation is mainly composed of clay and siliceous minerals, followed by calcite and feldspar, with a small amount of dolomite and pyrite, foraminifera, radiolarian and other micropaleontological development; according to the mineral composition, Paleontological characteristics and phosphate content, combined with microstructures, are used to identify 6 lithofacies types: foraminifera-rich fine-grained rocks, radiolarine-rich fine-grained rocks, phosphorous fine-grained rocks, clayey fine-grained rocks, feldspathic fine-grained rocks and lime-grained fine-grained rocks. The development of source rocks in Madingo formation is controlled by sea level rise and fall, upwelling, paleogeography and paleoclimate. The three stages of transgression / regression cycle are identified, and sea level rise and fall are determined by controlling water depth, redox conditions and sediment types. The organic matter content of radiolarian rich fine-grained rocks, phosphorous fine-grained rocks and foraminifera-rich fine-grained rocks is high, which is supposed to be the deposition period of two upwelling deposits of different scales, the Madingo formation. In the study area, there are three stages of paleoclimate: drought climate, relative humid climate and humid climate, and the relatively closed water environment is favorable to the preservation of organic matter, which is related to the activities of salt diapir. The abundance of organic matter and the type of organic matter in source rocks are affected to some extent by controlling the input of terrestrial organic matter in the ocean.
【作者单位】：中国地质大学(武汉)构造与油气资源教育部重点实验室;中国地质大学(武汉)资源学院;中国海洋石油研究总院;
【基金】：国家重大科技专项“西非和南美海域重点区油气地质评价及关键技术研究”(2017ZX05032-001)
【分类号】：P618.13

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