渤南洼陷古近系沙三下亚段细粒沉积岩形成环境研究

发布时间：2018-08-02 16:16

【摘要】：近年来,页岩油勘探开发方面取得的成功,激发了学者对细粒岩的深入研究。然而目前,对细粒沉积岩的形成环境和沉积机理研究较为薄弱。本文以渤南洼陷古近系沙三下亚段细粒沉积岩为研究对象开展研究。首先对细粒沉积岩从岩心到薄片不同尺度的观察,结合地化数据分析,对研究区细粒沉积岩沉积特征进行分析。研究区细粒沉积矿物以碳酸盐、石英及黏土矿物为主,其次可见长石、黄铁矿、白云石、有机质及生物碎片。研究区沉积构造特征主要以纹层状和层状为主,存在有浊流或风暴等事件沉积形成的沉积构造现象。结合细粒沉积岩沉积学特征,对该区纹层成因提出了浑水沉积、半浑水沉积、清水沉积三种成因,同时存在有风暴再悬浮及浊流成因。通过对研究区取心井进行米兰科维奇旋回分析,发现研究区内偏心率和岁差对细粒沉积岩沉积演化具有明显的规律性。偏心率和岁差的共同影响了研究区沉积环境变化,进一步影响了陆源输入强度,最终影响细粒沉积岩垂向演化。在一个偏心率变化旋回中,自下而上有机碳含量呈低-高-低的变化规律。在一个岁差变化周期旋回中,自下而上,碳酸盐岩含量呈低—高—低规律变化,有机质含量呈高—低—高变化规律。结合天文旋回沉积特征,研究分析发现细粒沉积岩存在有五种沉积体系,分别为浑水沉积体系、半浑水沉积体系、清水沉积体系、浊流沉积体系和风暴再悬浮沉积体系。在一个岁差旋回周期内,可表现为“半浑水-清水-半浑水”或“浑水-半浑水-浑水”的沉积过程。受风暴作用导致再悬浮的细粒沉积岩多出现在浑水和半浑水沉积体系中。浊流沉积多发育在研究区沙三下亚段上部,在天文格架内多发生在浑水沉积体系中。
[Abstract]:In recent years, the success of shale oil exploration and development has inspired scholars to further study fine rock. However, the formation environment and sedimentary mechanism of fine-grained sedimentary rocks are relatively weak. In this paper, the fine sedimentary rocks of the Paleogene S3 lower member in Bonan depression are studied. Firstly, the sedimentary characteristics of fine grain sedimentary rocks in the study area are analyzed by observing the different scales of fine sedimentary rocks from core to thin slice, combining with geochemical data analysis. The fine grained sedimentary minerals in the study area are mainly carbonate quartz and clay minerals followed by feldspar pyrite dolomite organic matter and biological debris. The sedimentary tectonics in the study area are mainly lamellar and stratiform, and there are sedimentary tectonics formed by turbidite or storm events. Based on the sedimentary characteristics of fine-grained sedimentary rocks, the authors put forward three types of genesis of the laminae in this area: muddy water deposition, semi-muddy water deposition and clear water deposition, and there are storm resuspension and turbidite flow genesis at the same time. Based on the analysis of Milankovich cycles in coring wells in the study area, it is found that the eccentricity and precession have obvious regularity on the sedimentary evolution of fine-grained sedimentary rocks. The eccentricity and precession influence the variation of sedimentary environment in the study area, further influence the input intensity of land source, and finally influence the vertical evolution of fine sedimentary rocks. In an eccentricity cycle, the organic carbon content from bottom to top is low-high-low. In a precession cycle, from bottom to top, the carbonate rock content changes from low to high, and organic matter content from high to low to high. According to the characteristics of astronomical cycle deposition, it is found that there are five sedimentary systems in fine-grained sedimentary rocks, namely, muddy water sedimentary system, semi-muddy water sedimentary system, clear water sedimentary system, turbidite deposition system and storm resuspension sedimentary system. In a precession cycle, the sedimentary processes of "half muddy water-clear water-half muddy water" or "muddy water-half muddy water-muddy water" can be represented. The fine sedimentary rocks resuspended by storm are mostly found in muddy water and semi-muddy water deposition systems. Turbidity flow deposits are mostly found in the upper part of the lower submember of Sha 3 and in the astronomical framework in the sedimentary system of muddy water.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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