黔北毕节地区早—中侏罗世地层划分对比及沉积相分析

发布时间：2018-04-03 21:23

本文选题：早—中侏罗世　切入点：岩石地层　出处：《成都理工大学》2017年硕士论文

【摘要】：贵州侏罗纪地层出露较为局限,研究区位于黔北地区出露面积相对广泛。本文通过野外地质勘察,得到研究区内岩石、生物等资料,并以此为基础结合前人研究成果,对研究区地层进行了划分对比,并根据沉积相分析得出研究区早—中侏罗世沉积模式图。本文选择了位于研究区内代表性剖面共7条,其中实测剖面有4条,观测剖面3条,分别是:贵州省大方县高枧乡黎家湾珍珠冲段地层实测剖面;贵州省大方县响水乡山背后自流井组地层实测剖面;贵州省大方县响水乡响水滩中侏罗统新田沟组—沙溪庙组地层实测剖面;贵州省大方县新场乡马鬃岭侏罗系自流井组—新田沟组地层实测剖面;贵州省毕节太极场自流井组地层观测剖面。根据野外测制成果,得出研究区内的岩性以及岩石组合等特征,参考前人得出的研究区研究成果,本文综合分析而后提出一套合理的岩石地层划分方案,将研究区自下而上划分为自流井组,其中自流井组又分为綦江段、珍珠冲段、马鞍山段、东岳庙段、大安寨段,新田沟组,沙溪庙组,遂宁组。根据研究区内发现的古生物化石,得出其在地层中的分布规律、化石种类及其组合特征,依据依据古生物化石的地层分布及组合特征建立四个双壳类生物组合带及一个叶肢介类生物组合带,即双壳类Pseudocardinia组合带、Lamprotula(Eolamprotula)cremeri组合带、Lamprotula(Eolamprotula)-Psilunio组合带、Lamprotula(Eolamprotula)guangyuanensis-Undulatula组合带;叶肢介Euestheria ziliujingensis组合带。在研究区域内首次发现恐龙活动遗迹化石,于自流井组马鞍山段中部地层砂岩层面发现了蜥脚类恐龙足迹化石,成对排列共8枚,对当地的古环境、古地理、古气候的恢复和重建以及当地古脊椎动物群落演化史具有重要的研究意义。研究区内古生物化石较为丰富,根据其出露地层和化石特征及组合可进一步对年代地层进行划分,依据生物地层学方法将各个生物组合带的层位和分布规律进行区域横向比对,得出研究区自流井组对应辛涅缪尔期-托阿尔期,赫塘阶上部;新田沟组归于阿林阶;沙溪庙组对应卡洛维阶—巴柔阶;遂宁组对应牛津阶。根据研究区内的岩石地层、生物地层、沉积构造等特征综合分析得出了黔北毕节地区早—中侏罗世可划分为陆相沉积体系组,又分为湖泊相和湖泊三角洲相两种类型。湖泊相又分为两个亚相,即滨湖亚相和浅湖亚相,包括滨湖亚相的砂坪、砂泥混合坪和泥坪三个微相,以及浅湖亚相的浅湖砂坪、浅湖砂泥混合坪、介壳滩、浅湖泥坪和浅湖砂泥坪几个微相。湖泊三角洲相又分为三角洲前缘亚相,包含水下分流河道微相、分流间湾微相、河口砂坝微相。最后,根据毕节地区早—中侏罗世沉积相分析建立了黔北毕节地区沉积相模式,并得出研究区沉积相模式图。
[Abstract]:Guizhou Jurassic strata are limited, the study area is located in North Guizhou exposed area is relatively wide. Through field geological survey, obtained in the study area of rock, biological data, and on the basis of the results of previous studies, the strata in the study area are divided to ratio, and according to the sedimentary facies analysis of early - chart sedimentary model of Middle Jurassic. Based on the study area representative section 7, which measured section 4, observation section 3, namely: Guizhou province Dafang County Gao Jian Xiang Li Jia Wan zhenzhuchong formation measured profile; Dafang County Guizhou province ring River mountain behind the artesian well group the measured stratigraphic section; Dafang County Guizhou province Xiangshui township of Xiangshui beach Middle Jurassic Xintian formation of Shaxi Temple ditch group section; Guizhou province Dafang County Xinchang Township Mazongling Ziliujing formation Xintian formation section ditch; Guizhou Province, Bijie Tai Chi Ziliujing formation section. According to the field measurement results of observation, the characteristics of the study area lithology and rock assemblage, the study area according to the previous research results, this paper then puts forward a set of reasonable lithostratigraphic classification scheme, the study area is divided into the bottom-up artesian well group, and the artesian well group Qijiang is divided into segments, zhenzhuchong segment, Ma'anshan segment, DONGYUEMIAO member, Da'anzhai, Xintian ditch group, Shaxi Temple group, Suining group. According to the study area found fossils, obtained in the formation of the distribution, species and fossil assemblages, stratigraphic distribution and combination of the basis for the fossils to build four bivalve assemblage and a biological conchostracon assemblage, namely bivalve assemblage zone Pseudocardinia, Lamprotula (Eolamprotula) cremeri combined with Lamprotula (E. Olamprotula) -Psilunio Lamprotula (Eolamprotula) combined with guangyuanensis-Undulatula combined with Euestheria ziliujingensis; conchostracon assemblage. Trace fossils of dinosaur activity was first discovered in the study area, in the central section of Ma'anshan formation sandstone in artesian well group level found sauropod dinosaur footprint fossils are arranged in pairs, a total of 8 medals, the ancient environment, local the ancient geography, has an important significance to the restoration and reconstruction of paleoclimate and the evolution of local ancient vertebrate fossils within history. The study area is abundant, according to the exposed strata and fossils and combination can further divide the chronostratigraphic, biostratigraphic methods based on various biological assemblage horizons and distribution area horizontal comparison, that the study area of artesian well group - Toal Muir corresponding Mnemosyne, upper hettangian new group to ditch; Alin order; Shaxi Temple group corresponding to Calloway order - Bajocian; Suining Oxford order. According to the research group of the corresponding region of the lithostratigraphy, biostratigraphy, comprehensive analysis of sedimentary structure feature that Bijie area of North Guizhou early - Middle Jurassic can be divided into the continental sedimentary system group, and divided into lake facies and lake delta facies two types of lake facies. It is divided into two subfacies, i.e. Binhu subfacies and shallow lacustrine subfacies, including Binhu sand flat, mixed flat and mud flat sand and mud three microfacies, and shallow lake facies of the shallow lake sand flat, shallow lake sand mud mixed flat, on the beach, the shallow lake mud flat and shallow lake sand mud flat several microfacies. Lake delta facies is divided into delta front subfacies include subaqueous distributary channel, interdistributary bay microfacies, estuary sand dam microfacies. Finally, according to the Bijie region in the early - Middle Jurassic sedimentary facies analysis established sedimentary area in North Bijie Guizhou phase mode, and The pattern of sedimentary facies in the study area is drawn.

【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】：P534.52

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