【作者】 马明；

【导师】 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2020， 博士

【摘要】 本论文在基于大量地震资料、钻井资料、野外资料和测试分析资料的基础上,以“动态、综合、整体”思想为指导,运用构造解析、盆山耦合等分析技术对中央古隆起形成演化过程、鄂尔多斯地区早古生代构造特征及其演化、沉积-古环境对构造演化的响应特征和深部动力学背景进行研究,取得以下认识:中央古隆起主要形成于早古生代,其演化过程可分为五个阶段:第一阶段为早寒武世,受前寒武古构造影响,中央古隆起雏形显现;第二阶段为中、晚寒武世,中央古隆没有发生强烈隆升,中央古隆起范围内发育中上寒武统,在晚寒武世末期,中央古隆起有所隆升;第三阶段为早奥陶世,受寒武纪末期至早奥陶世怀远运动影响,早奥陶世中央古隆起隆升幅度较大,古隆起顶部无下奥陶统发育;第四阶段为中奥陶世,中央古隆起隆升强度下降,逐渐变为一水下隆起;第五阶段为晚奥陶世,受加里东运动影响,中央古隆起大规模隆升,下伏地层遭受剥蚀,仅在盆地西、南缘有上奥陶统发育,至此中央古隆起定型。鄂尔多斯地区下古生界断裂发育,根据断裂的平面展布特征,可将断裂分为NE向、NW向、近SN向和近EW向四组。根据断裂的展布规模,可将断裂分为二级、三级、四级和五级断裂四个级别,二级、三级断裂对四级、五级断裂具有控制作用,断裂在平面上有羽状和帚状两种组合方式。鄂尔多斯地区西、南缘发育伸展构造样式、挤压构造样式和反转构造样式,构造样式空间分布具有“垂向分层”特征,与盆地演化阶段对应。伸展构造样式发育于中新元古界、寒武系和奥陶系下部,向上变形程度降低,挤压构造样式发育于上奥陶统中。基于最新资料,认为在鄂尔多斯地区怀远运动发育时限应从晚寒武世末开始显现,直至早奥陶世末,整个怀远运动分为两幕完成,第一幕为晚寒武世末,早奥陶世初,第二幕是早奥陶世末。鄂尔多斯地区早古生代沉积序列形成受构造特征影响显著,中央古隆起形成演化对一些特征性的沉积建造发育也有影响。通过Sr/Cu和CIA指标分析了鄂尔多斯地区西、南缘早古生代古气候和风化程度特征及其对构造演化的响应,发现西、南缘早古生代大多数时期气候以湿温气候为主,但存在两个气候从湿温变为干热的极性变化阶段,分别是晚寒武世至早奥陶世,和中奥陶世至晚奥陶世,与盆地演化阶段相对应,推测是对怀远运动和加里东运动的响应。鄂尔多斯地区早古生代动力学背景存在时空差异性,寒武纪—中奥陶世,南缘和西缘中、南段动力学背景主要受秦岭洋影响,构造环境为被动大陆边缘环境,西缘北段这一时期主要受北祁连洋影响,受北祁连洋开始双向俯冲的影响,阿拉善南缘及鄂尔多斯西缘北段构造属性主要表现为岛弧环境;晚奥陶世,南缘和西缘中、南段,秦岭洋已完全关闭,二郎坪弧后盆地正式形成,构造环境为主动大陆边缘环境,在西缘北段这一时期,从中祁连地块至阿拉善地块,发育典型的沟-弧-盆地体系,构造背景也为主动大陆边缘环境。更多还原

【Abstract】 Based on the plenty of seismic data,drilling well data,field data as well as geochemical data,we analysed the evulotion of the Central Paleo-Uplift in Ordos Basin,the characterisitcs of the structural,sedimentary and paleo-environment in the Ordos Basin during the Early Paleozoic,and the geodynamics via the structural analysis technique,mountain-basin coupling analysis technique,and dynamic-systematic – comprehensive analysis technique,respectively.We drawed some conclusions as shown below:the Central Paleo-Uplift was formed in the Early Paleozoic,and its evolution can be divided into five stages: The first one was the Early Cambrian,the shape of the Central Paleo-Uplift developed under the influence of the pre-structural framework;The second stage was form the Middle Cambrian to the Late Cambrian,the uplift of the Central Paleo-Uplift was weak,so the Middle and Upper Cambrian developed.However,under the influenced the Huaiyuan Movement at the end of the Late Cambrian,the Central Paleo-Uplift uplifted with small sacall;The third one was the Early Ordovician,affected by the Huaiyuan Movement,the Central Paleo-Uplift uplifted with a middle scall,the there was no Lower Ordovician formed;The fourth stage was the Middle Ordovician,the Central Paleo-Uplift descended gradurally,until into the sea water;The last stage was the Late Ordovician,influenced by the Caledonian movement,the Central Paleo-Uplift uplifted dramatically,the stratums on the Central Paleo-Uplift was corroded,the final shape of the Central Paleo-Uplift was decided.Abundant faults were developed in the Lower Palaeozoic,which can be divided into four types according to the trending,they are NE trending,NW trending,NS trending and EW trending,respectively.Meanwhile,the faults can also be ranked four grade basded on their scall,which are second,third,fourth and fifth grade,respectively.And the former two controlled the latter two.There are three types of structural style formed in the Lower Palaeozoic in the southern and western margin of the Ordos Basin,which are extend style,extruding style and inverted style,respectively.Furthermore,the diferent style distributed in the different stratums,this kind of phenomenon correspond with the basin evolution.We belived that the initiation of Huaiyuan Movement in the Ordos region was from the end of the Late Cambrian,and the whole process of the Huaiyuan Movement canbe divided into two episodes,the first one was at the end of the Late Cambrian,the second one was occurred at the end of the Early Ordovician.The sedimentary features was obviously controlled by the tectonic characteristics in Ordos Basin.And the evolution of the Central Paleo-Uplift affected some special sedimentary formation.We also analysed the Early Paleozoic paleo-climate and paleo-weathering of western and southern margin of the Ordos Basin through Sr/Cu and CIA index.The results shown that the paleo-climate was wet and warm during the most of period,but feateured by two special stages,which were the Late Cambrian to the Early Ordovician,and Middle Ordovician to Late Ordovician,respectively.During these two stage,the paleo-climate changed from wet and warm to dry and hot.We considered that these two special stage corresponded to the Huaiyuan Movement and Caledonian movement,respectively.The geodynamics of the Ordos baisn variaed with time and region.From the Cambrian to the Middle Ordovician,the geodynamics of the southern margin and middle and south parts of the western margin was affected by the Qinling Ocean,the tectonics environment was the passive continental margin environment.But the north part of the western margin was cotronlled by the North Qilian Ocean during this stage,the tectonics environment was the arc environment.During the Late Ordovician,the trench-arc-basin system was formed in the both margin,the tectonic environment was the active continental environment.更多还原