湖相深水细粒物质的混合沉积作用探讨

发布时间：2018-05-30 23:28

  本文选题：细粒物质 + 混合沉积　； 参考：《古地理学报》2017年02期

【摘要】：沉积物的混合是自然界的普遍现象,湖盆中广泛发育的深水细粒沉积岩本身就是一类混积岩。以东营凹陷古近系沙河街组三段下亚段—沙河街组四段上亚段细粒沉积岩为研究对象,通过厘米级岩心观察描述、小型沉积构造解剖、岩石薄片观察、X射线衍射全岩矿物分析及微量元素测试等方法,研究细粒物质的产出状态和混合方式;分析湖盆流体、气候及水体性质对细粒物质迁移、混合、沉积的控制作用,尝试探讨细粒物质的混合沉积机制。结果表明,湖相深水细粒沉积岩既有物质成分上的混合,也有结构的混合,且在宏观与微观的不同尺度均存在混合;混合沉积作用有均匀混合、纹层叠置混合、不均匀团块状混合等类型。纹层叠置混合沉积是最主要的混合沉积方式,依据纹层接触关系、所占比例及矿物产出状态可分为泥砂—灰纹层叠置混合型、泥—灰纹层叠置混合型、泥砂粒序—灰纹层叠置混合型、灰—泥—云纹层叠置混合型等。湖相深水细粒物质的混合沉积作用类型多且往往受多个因素同时控制,气候及水动力条件是控制细粒混合沉积岩发育的最主要因素,不同流体(浊流和底流)作用下的细粒沉积物混合作用存在差异。气候引起湖水性质变化及水体分层,从而控制不同类型细粒物质的絮凝沉降及化学沉积。不同构造部位、不同水体深度的混合作用不同;相同构造部位在垂向上也存在混合沉积方式的差异。
[Abstract]:Sediment mixing is a common phenomenon in nature. Deep-water fine-grained sedimentary rocks, which are widely developed in the lake basin, are a kind of migmatite. The fine sedimentary rocks of the lower submember of the third member of the Shahejie formation of Paleogene and the upper submember of the fourth member of the Shahejie formation in Dongying Sag are taken as the research object. The observation and description of the centimeter core are used to dissect the small sedimentary structure. X-ray diffraction analysis of whole rock minerals and trace element measurement were used to study the state and mixing of fine particles, and to analyze the migration and mixing of fine-grained materials by the fluid, climate and water properties of the lake basin. The mechanism of mixed deposition of fine-grained materials is discussed. The results show that the lacustrine deep-water fine-grained sedimentary rocks are mixed in both material composition and structure, and are mixed at different scales of macroscopical and microcosmic. Heterogeneous lumps, block mixing, etc. According to the contact relation of grain layer, the proportion and the state of mineral production can be divided into mud sand and gray grain superposition mixed type, mud and gray grain stacking mixed type, according to the contact relation of grain layer, it is the most important mixed deposition method. The mud-sand sequence-gray-grain stacked mixed type, the gray-mud-moire stacked mixed type, etc. There are many types of mixed sedimentary processes of lacustrine deep-water fine-grained materials and are often controlled by multiple factors at the same time. Climate and hydrodynamic conditions are the main factors controlling the development of fine-grained mixed sedimentary rocks. There are differences in the mixing of fine sediments under the action of different fluids (turbidity current and bottom current). Climatic changes of lake water properties and water stratification control the flocculation sedimentation and chemical deposition of different types of fine particles. The mixing processes of different structures and different water depths are different, and the mixing and deposition patterns of the same structures are also different in vertical direction.
【作者单位】： 中国石油大学(华东)地球科学与技术学院;中国石化胜利油田公司勘探开发研究院;中国石化胜利油田博士后流动工作站;
【基金】：国家自然科学基金项目(编号:41372107) 国家重点基础研究发展计划(973)项目(编号:2014CB239102)资助~~
【分类号】：P512.2
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本文编号：1957306