湖相深水块状细粒沉积岩的特征及成因 ——以济阳坳陷始新统为例

Characteristics and genesis of lacustrine massive fine-grained sedimentary rock: taking Eocene Jiyang Depression as an example

马芳侠 王力 罗丹婷 张译丹 葛云锦 杜克峰1

陕西延长石油（集团）有限责任公司研究院，陕西 西安 710075 中国地质大学（北京）能源学院，北京 100083

Research Institute of Shaanxi Yanchang Petroleum(Group) Co., Ltd., Xi′an 710075, China School of Energy Resources, China University of Geosciences, Beijing 100083, China

针对湖相块状细粒沉积岩成因的研究较少，其特征和成岩机制尚不明确。文中通过观察济阳坳陷始新统湖相细粒沉积岩，在1 093 m岩心中识别出95 m块状细粒沉积岩。孢粉和地球化学数据显示，形成块状细粒沉积岩的水体还原性和含盐度比相邻暗色页岩低，而气候更偏暖湿；连井剖面显示，块状细粒沉积岩位于浊积砂岩前端。再考虑其底部微冲刷和突变、顶部截切，以及内部矿物组分杂乱分布的特征，综合判断济阳坳陷始新统块状细粒沉积岩为浊流末梢沉积。温暖潮湿的气候和高沉积速率是块状细粒沉积岩沉积的主要触发机制，稀浊流能够大量携带浮游生物，并将其沉积在浊积泥中，可以作为一种潜在的有效烃源岩。

There are few studies on lacustrine massive fine-grained sedimentary rock, and its characteristics and diagenesis mechanism are not yet clearly defined. Based on core observation of the lacustrine environment of the Jiyang Depression, Bohai Bay Basin, China, we distinguished 95 m massive fine-grained sedimentary rock from the 1,093 m core. Pollen and geochemistry data prove that the water reducibility and salinity of massive fine-grained sedimentary rock are lower than that of adjacent dark shales, and the climate was warmer and more humid. The connecting-well section shows that massive fine-grained sedimentary rock is in the distal part of deep-water gravity-driven sandstone units. Considering the characteristics of the bottom gentle erosion and abrupt changes, top truncation, the disorganized and chaotic distribution of internal mineral components, the Eocene massive fine-grained sedimentary rock in the Jiyang Depression is comprehensively judged as turbidity-end deposits. Warm and humid climate and high deposition rate are two main trigger mechanisms of massive fine-grained sedimentary rocks. Dilute turbidity can carry large amounts of plankton and deposit it in turbid mud, which can be used as a potential effective source rock.

10.6056/dkyqt201803002