山东乳山盆地下白垩统震积岩特征及其构造地质学意义

发布时间：2018-07-09 19:24

本文选题：乳山盆地 + 下白垩统　；参考：《成都理工大学》2017年硕士论文

【摘要】：山东乳山盆地位于渤海湾盆地南部,受郯-庐断裂带活动的影响,盆地地震活动强烈,发育一系列与地震活动相关的地震事件沉积构造,成为研究震积岩较为理想的天然实验室。本论文依托山东乳山盆地下白垩统止凤庄组露头、剖面,以沉积地质学、矿物学-岩石学、沉积地球化学、构造地质学等理论为指导,详细研究了止凤庄组地层发育特征、震积岩类型及其几何学、运动学特征。并通过碎屑锆石年代学手段,约束震积岩形成的时间,揭示了晚侏罗世-早白垩世郯庐断裂活动的性质及其地质记录。山东乳山盆地下白垩统止凤庄组属莱阳群底部,为莱阳群五个组级(由下至上分别为林寺山组、止凤庄组、水南组、龙旺状组、曲格庄组)单元之一,与上覆水南组、下伏林寺山组皆呈整合接触。主要由冲积扇、河流相的砾岩、含砾砂岩、粉砂岩构成。砾石砾径大小不一,砾岩的单层厚度在2-4m左右,砾石大小多数在5-20cm之间,有的可达50cm,分选较差,磨圆中等;含砾砂岩单层厚度在5-10m,分选磨圆由较差-较好不等。填隙物中杂基含量在0-10%之间,胶结物主要为硅质胶结,其次为铁质胶结。同时发育平行层理、板状层理、冲刷-充填构造、波状层理等一系列沉积构造;在这套地层中发育液化砂泥岩脉、液化卷曲变形构造、球枕状-砂枕状构造、泄水构造(火焰状构造)、阶梯状微断层等5种地震沉积构造,并根据其成因动力学,结合前人研究成果将山东乳山盆地震积岩分为2大类(软沉积物变形构造和硬岩层脆性变形构造)、3小类(液化变形构造、挤压变形构造、脆性变形构造),其中液化变形构造又可分为泄水构造(火焰状构造)、砂枕-球枕状构造、液化砂泥岩脉、液化卷曲变形构造等4种类型;同时通过对ZFZ-2样品碎屑锆石U-Pb测年分析,其年龄范围107-123Ma,得出其206Pb/238U表面年龄加权平均值为114.5Ma,这与前人研究测试数据一致,即认为软沉积变形事件发生于114.5Ma之后。通过对研究区目标层位震积岩当中广泛发育波浪状背斜构造,其中轴线角度从65度变为80度,以及液化砂泥岩脉脉体方向的转变的研究,揭示了其形成机制可能与在晚侏罗-早白垩世时期(145.5~99.6Ma),郯-庐断裂带发生左旋走滑产生的左旋剪切作用力有关。
[Abstract]:The Shandong Rushan basin is located in the south of Bohai Bay basin. Influenced by the activity of the Tan-Lu fault zone, the basin has strong seismic activity and develops a series of sedimentary structures related to seismic events. It is an ideal natural laboratory for studying seismite. Based on the outcrop and profile of the Lower Cretaceous Zhifengzhuang formation in the Rushan Basin, Shandong Province, and guided by the theories of sedimentary geology, mineralogy-petrology, sedimentary geochemistry and tectonic geology, the stratigraphic development characteristics of the Zhifengzhuang formation are studied in detail in this paper. Types of seismogenic rocks and their geometries and kinematic characteristics. By means of clastic zircon chronology, the formation time of seismite is restricted, and the characteristics and geological records of Tanlu fault activity in late Jurassic-early Cretaceous are revealed. The Lower Cretaceous Zhifengzhuang formation belongs to the bottom of the Laiyang Group in the Rushan Basin, Shandong Province. It is one of the five units of the Laiyang Group (Linshishan formation, Zhifeng Zhuang formation, Shuinan formation, Longwang formation, Qugezhuang formation) from the bottom of the lower Cretaceous. All of the lower Fulinsi formation were integrated contact. Mainly by alluvial fan, fluvial facies conglomerate, gravel sandstone, siltstone composition. The gravel diameter is different, the single layer thickness of gravel is about 2-4m, the gravel size is mostly between 5-20cm, some can reach 50 cm, the separation is poor, the grinding circle is medium, and the single layer thickness of gravel sandstone is 5-10 m, the separation and grinding circle varies from poor to better. The content of hetero group in the interstitial material is between 0 and 10%, and the cement is mainly siliceous cemented, followed by iron cementation. A series of sedimentary structures, such as parallel bedding, plate bedding, scour filling structure, wave bedding and so on, have been developed in this set of strata, such as liquefaction sand and mudstone vein, liquefaction crimp deformation structure, ball pillow and sand pillow structure, Five kinds of seismic sedimentary structures, such as discharge structure (flame structure), step microfault, etc., and according to their genetic dynamics, Based on the previous research results, the seismogenic rocks of Shandong Rushan basin are divided into two types (soft sediment deformation structure and hard rock brittle deformation structure) and three sub-types (liquefaction deformation structure, compressional deformation structure, compression deformation structure). Among them, the liquefaction deformation structure can be divided into four types: discharge structure (flame structure), sand pillow-ball pillow structure, liquefaction sand and mudstone vein, and liquefaction convoluted deformation structure. At the same time, the zircon U-Pb dating of ZFZ-2 sample shows that its age range is 107-123 Ma, and the weighted average surface age of 206Pb / 238U is 114.5 Ma, which is consistent with the previous data, that is, the deformation event of soft deposition occurred after 114.5 Ma. Through the study of the development of wavy anticline structures in the seismogenic rocks of the target horizon in the study area, the central axis angle has changed from 65 degrees to 80 degrees, and the direction of the veins of the liquefied sand and mudstone has been changed. It is suggested that the formation mechanism of Tan-Lu fault zone may be related to the left-lateral shear force produced by left-lateral strike-slip during the late Jurassic-early Cretaceous period (145.5 ~ 99.6 Ma).
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.2;P588.2

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