渝东南地区地处上扬子前陆盆地川中隆起与黔中隆起之间，古生界发育多套厚层黑色页岩，其中下志留统龙马溪组黑色页岩分布极为广泛，为区内重要的烃源岩。根据探井岩心X-射线衍射测试结果，页岩中粘土矿物的组合类型为伊利石、有序的伊/蒙间层和绿泥石，其中伊利石相对含量最多，平均含量为54%，伊/蒙间层次之，平均含量为36%。在纵向上粘土矿物的组合类型没有变化，但随着埋深的增加，伊/蒙间层不断向伊利石进行成岩转化，绿泥石的含量逐渐降低，埋藏加热作用在成岩过程中起主导作用。粘土矿物的组合类型也反映了干旱的古气候和富含钾、镁、铁离子的古水介质特征，盐碱性水介质在成岩过程中起到了重要的控制作用。伊/蒙间层的间层比和镜质体反射率表明龙马溪组黑色页岩已达到晚成岩阶段，有机质演化属于过成熟期。%The southeastern Chongqing area is situated between middle Sichuan uplift and middle Guizhou uplift both in the upper Yangtze foreland basin. The Paleozoic Group had developed multiple sets of thick black shale, in which, lower Silurian Longmaxi black shale distributed widely, a significant source rock in the area. According to drilling core X-ray diffraction tested results, clay mineral assemblage type in shale is illite, ordered intercalated illite/montmorillonite beds, in which, relative content of illite is at most, average content is 54%, intercalated illite/montmorillonite beds the second with average content 36%. Vertically, clay mineral assemblage type unchanged, but along with buried depth deepening, intercalated illite/montmorillonite beds lithogenetically changed into illite without cease, chlorite content gradually decreasing, burial heating effect dominated the lithogenetic process. Clay mineral assemblage type al⁃so reflected arid dry paleoclimate and potassium, magnesium, ferric ions rich paleoaquatic medium played an important controlling role in lithogenetic process. Intercalated illite/montmorillonite beds ratio and vitrinite reflectance indicated Longmaxi black shale had reached later lithogenetic stage, organic matter evolution in overmature stage.
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