鄂尔多斯盆地北缘大佘太地区奥陶系碳酸盐微相及其沉积环境分析

发布时间：2018-03-22 13:31

本文选题：微相分析　切入点：碳酸盐岩　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：鄂尔多斯盆地北缘的大地构造位置位于华北板块古亚洲造山带的交界处。大佘太地区位于阴山西段之南侧,内蒙乌拉特前旗的北部。区内奥陶系出露齐全,由下向上划分为:下奥陶统山黑拉组,中奥陶统二哈公组、乌兰胡洞组,上奥陶统白彦花山组。内蒙古乌拉特前旗佘太镇地区的奥陶系位于鄂尔多斯盆地(华北地台)的最北缘,相对于盆地东、南和西缘奥陶系的研究程度,盆地北缘奥陶系研究程度相当低。本文通过对内蒙古乌拉特前旗大佘太镇山黑拉、乌拉特前旗大佘太镇白彦花山两条剖面的野外剖面实测、室内显微观察和微相分析,探讨内蒙乌拉特前旗大佘太镇奥陶系沉积环境和构造环境的演化。对研究区奥陶系碳酸盐岩微相的研究,共识别出20种微相。其中在山黑拉剖面划分出14种微相;白彦花山剖面划分出14种微相。将结合野外观察和微相划分,并与Wilson标准微相进行对比划分,将研究区的沉积环境划分为盆地边缘相、斜坡相、台地边缘浅滩相、开阔台地相、局限台地相以及蒸发台地相六个相带,并总结了各沉积环境的沉积特征。沉积环境的改变,主要反映在沉积物的性质,即成分与组构的变化上。通过对两条剖面沉积相带组合的比较,认为研究区山黑拉期沉积环境为台地相,从下向上为开阔台地变化为局限台地沉积,其中开阔台地以发育鲕粒灰岩、砂屑灰岩为特点,表现为强水动力环境;二哈公组的沉积环境为台地相夹有斜坡相,从下向上为开阔台地,台地边缘浅滩和蒸发台地沉积;乌兰胡洞期沉积环境为台地相和斜坡相,自下向上为蒸发台地,开阔台地,局限台地和缓坡沉积;白彦花期从下向上主要表现为深水盆地和缓坡沉积环境。
[Abstract]:The tectonic position of the northern margin of the Ordos Basin is located at the junction of the North China plate Paleo-Asian orogenic belt. The Dashetai area is located on the southern side of the western part of the Yinshan Mountains, and the northern part of the Qianqi of Wulat, Inner Mongolia. The Ordovician system is well exposed in the area. The lower Ordovician Haila formation, the Middle Ordovician Erhagong formation, the Wu Lan Hu Dong formation, Upper Ordovician Baiyan Huashan formation. Ordovician Ordovician is located in the northernmost margin of the Ordos Basin (North China platform) in Shataizhen area, Qianqi, Wulat, Inner Mongolia, and is relative to the study of Ordovician in the east, south and west margin of the basin. The study of Ordovician in the northern margin of the basin is quite low. The field profile of the two sections of Shanhela, Dasshe Taizhen, Qianqi, Wulat, Wulat Qianqi and Baiyanhuashan, Wulat Qianqi, Inner Mongolia are measured, microscopic observation and microfacies analysis are carried out in the laboratory. This paper discusses the evolution of the sedimentary and tectonic environments of Ordovician in Dashetai Town, Qianqi of Wulat, Inner Mongolia. Twenty kinds of microfacies have been identified in the study area of Ordovician carbonate rock microfacies, among which 14 kinds of microfacies have been identified in the Shanhelia section. There are 14 kinds of microfacies in Baiyan Huashan section. The sedimentary environment of the study area is divided into basin margin facies, slope facies, platform margin shoal facies, open platform facies, and Wilson standard microfacies, which are combined with field observation and microfacies division, and the sedimentary environment of the study area is divided into basin margin facies, slope facies, platform margin shoal facies and open platform facies. The sedimentary characteristics of each sedimentary environment are summarized. The change of sedimentary environment is mainly reflected in the nature of sediment. That is, the change of composition and fabric. By comparing the assemblages of two sedimentary facies belts in the profile, it is considered that the sedimentary environment of the study area is platform facies, and from the bottom up to the open platform, the sedimentary environment is limited platform deposition. The open platform is characterized by the development of oolitic limestone and sandy limestone, which is characterized by strong hydrodynamic environment, the sedimentary environment of Erhagong formation is platform facies with slope facies, from the bottom up to the open platform, platform edge shoal and evaporation platform deposition. The sedimentary environment of Hu Dong period of Wu Lan is platform facies and slope facies, from the bottom up to evaporation platform, open platform, limited platform and gentle slope deposition, and Baiyan flowering period mainly shows deep water basin and gentle slope sedimentary environment from the bottom up.
【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】：2015
【分类号】：P534.42

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