【作者】 李洁；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 地质学， 2011， 博士

【摘要】 本论文在借鉴前人研究成果的基础上,以“构造控盆、盆控沉积、沉积控组合”为指导。运用沉积学、地层古生物学、高分辨率层序地层学、沉积地球化学、地球物理学等理论和技术方法,将鄂尔多斯盆地构造演化与全球构造背景相结合,以野外露头、测录井和地震资料为基础资料,研究了晚古生代鄂尔多斯盆地的沉积层序充填特征与物质分布规律,主要内容和成果如下:(1)从全球板块构造格局出发,着眼于大华北区域背景,以古亚洲域、特提斯构造域、滨太平洋构造域三大构造动力体系复合控制影响鄂尔多斯盆地不同构造演化阶段的形成、发育为指导思想。分析了晚古生代鄂尔多斯盆地主要受控于古亚洲域和古特提斯构造域的地球动力学背景;(2)通过研究鄂尔多斯盆地上古生界的岩石地层、生物地层和年代地层,将野外剖面和钻井进行了系统的地层划分与对比。运用地层过程-响应沉积动力学原理和以基准面旋回为参照面的高分辨率层序地层学理论及方法,进行了层序界面类型和划分标志研究。识别出了6种不同成因类型的层序界面,以及3种基本类型和7种亚类型的不同级次基准面旋回充填样式。将上古生界识别并划分为3个超长期旋回、20个长期旋回、47个中期旋回及若干短期旋回层序,最终建立了层序地层格架;(3)以沉积地球化学指标为主,结合海相地层分布、古生物、沉积构造、岩石学、成岩作用等各方面证据为参照,分别建立了盆地东西向与南北向的地化基干剖面,对盆内不同地区不同层位的地化测试结果进行了分析对比。在此基础之上,主要针对早二叠世山西期沉积环境进行了较为深入的分析,认为晚古生代鄂尔多斯盆地海陆转换的关键时期是山西末期(山1期);(4)在前人研究的基础之上,优选不同时期所对应的岩石地层单元的厚度图,近似刻画了整个古生代鄂尔多斯盆地不同演化阶段的古构造特征,以便进一步深化盆内中央古隆起形成演化过程的认识。研究结果表明,真正的中央古隆起形成于晚寒武世,并在奥陶系马家沟期反映最为明显。而中央古隆起对晚古生代的影响主要表现在晚石炭世-早二叠世早期(本溪期-山西期),并伴随盆地东西拉张背景向南北挤压应力的转化,于中二叠世下石盒子期彻底消亡。根据上述认识,将整个古生代鄂尔多斯盆地中央古隆起形成演化划分为6大阶段,并重点讨论了晚古生代中央古隆起周缘的沉积格局;(5)在晚古生代鄂尔多斯盆地海陆转换关键时期厘定的基础上,结合晚古生代中央古隆起调整、消亡过程的分析,通过以华北盆地为背景的构造-古地理格局图的编制。进一步将晚古生代鄂尔多斯盆地划分为三大沉积演化阶段,即①晚石炭世-早二叠世早期(本溪期-太原期)的受限陆表海充填发育阶段;②早二叠世晚期(山西期)的残余陆表海-近海湖盆充填发育阶段;③中晚二叠世(下石盒子期-石千峰期)的内陆坳陷湖盆充填发育阶段。在此基础之上,讨论了各阶段所对应的沉积演化特征和古地理格局;(6)通过野外剖面、岩心、测井和地震资料,研究了盆地上古生界典型沉积相的形成发育机理与沉积特征。一方面,对晚石炭世-早二叠世早期(本溪期-太原期)发育的陆表海-障壁海岸-浅水三角洲在时空上共生而形成的陆源碎屑与碳酸盐混合沉积进行了重点探讨。通过其形成发育机理的深入剖析,将该类沉积区分为混积岩和混积层系2大类型,并进一步识别出浅水三角洲型、障壁海岸型与陆表海浅海型3种主要类型的混合沉积环境。在此基础之上,结合混合沉积环境的时空分布规律分析,建立了该时期的混合沉积模式;另一方面,对整个晚古生代典型演化阶段发育的浅水三角洲进行了系统研究。通过其形成发育机理的深入剖析,将该类沉积区分为陆表海缓坡型浅水曲流河三角洲(太原期)、河控-潮控缓坡型浅水辫状河三角洲(山2期)、近海湖盆缓坡型浅水曲流河三角洲(山1期)与湖泊缓坡型浅水辫状河三角洲(盒8期)4种主要类型,并针对不同类型的发育特征进行了规律性和差异性研究。在此基础之上,建立了不同类型浅水三角洲沉积模式;(7)通过层序地层格架的建立,海陆转换关键时期的厘定,以及中央古隆起调整、消亡过程的分析,在盆地沉积演化阶段划分的基础之上,讨论了晚古生代鄂尔多斯盆地沉积物分布规律及沉积层序充填演化过程。以超长期基准面旋回为单元,结合油气勘探的重点层位,编制了超长期基准面升降过程中不同阶段的层序岩相古地理图和砂体等厚图,揭示了不同时期的沉积物分布规律、古地理演化特征与砂体展布规律。在此基础之上,通过各超长期基准面旋回沉积层序充填示意模式的建立,较为深入的讨论了盆地的沉积层序充填演化过程中的规律性和差异性。更多还原

【Abstract】 In this thesis, drawing on the basis of previous research, guiding by the academic ideology of "structural control basin, basin control sediment, sediment control combination", emphasizing restriction of global tectonic to the tectonic evolution of Ordos basin,using those theories of sedimentology, paleontology, high-resolution sequence stratigraphy, sedimentary geochemistry and geophysics, based on outcrops and logging and seismic data, studied the regularity of sedimentation-sequence filling characteristics and sediments distribution in the late Paleozoic Ordos basin. The main content and achievements are as follows:First, starting from the global pattern of plate tectonics, focusing on the Great North China regional context, the guiding ideology are the superimposed tectonic dynamic and compound of the Paleo-Asian domain, Tethyan tectonic domain and Sea Pacific tectonic domain ,which control and influence the tectonic evolution of the Ordos Basin at different stages of the formation and development. Based on the above analysis, the Ordos Basin Paleozoic is mainly Controlled system of the Paleo-Asian tectonic geodynamic background dynamics.Second, by studying lithostratigraphy, biostratigraphy and chronostratigraphy of the upper Paleozoic in Ordos basin, the outcrops and drilling is carried out a systematic stratigraphic division and contrast. The author takes the stratigraphic and sedimentary process-response dynamic principles as a theoretical basis, and applies the theory and technology of the high-resolution sequence stratigraphy on base-level cycle. After research on the types of sequence boundary and classification standard, identifing six kinds of different causes of sequence boundaries and three basic types, seven subtypes different grade of base-level cycle sequence filling patterns. Finally, sequence stratigraphy division plan of lower Paleozoic in Ordos basin is set, the upper Paleozoic can be divided into three super long-term, twenty long-term, fouty-seven medium-term and several short-term cyclic sequences, and sequence stratigraphy framework is established. Third, using sedimentary geochemical proxies, distribution of marine stratum, fossils, sedimentary tectonics, petrology and sedimentary diagenesis, establishing the geochemical proxies section of east-west and north-south in Ordos basin, and analying the test results of different layers in different regions. On the base of the above analysis, the depositional environment during Shanxi period of early Permian was deeply analyzed in this paper. The author think that the conversions of marine-continental facies during the upper Paleozoic in Ordos basinis is later Shanxi period.Forth, referring to the predecessors’s research, choosing isopach map of different periods of lithostratigraphic units, approximately characterizing the different stages of the ancient structural features during Paleozoic in Ordos basin, furtherly strengthening the understanding of formation and evolution of central paleouplift. The results show that the real central paleouplift is formed during late Cambrian, and reflects obviously during the Majiagou period of Ordovician. The main influences of the late Paleozoic is the late Carboniferous-early Permian, and die away from the diversification background of east-western extension and north-southern extrusion in the Permian period of Lower Shihezi. Summary, the formation and evolution of central paleouplift of the Paleozoic is divided into six major stages in Ordos basin, and discussing the deposition distribution of it.Fifth, On the basis of the changes of marine-continental facies during late Paleozoic in Ordos basinis, and analying the adjustment and disappearance of central paleouplift in the Paleozoic, the structure paleogeographic of North China basin are drew systematic. The sedimentary evolution of Ordos basin is divided into three major stages, including restricted epeiric sea in the late Carboniferous-early early Permian (Benxi-Taiyuan period), remaining epicontinenta sea and offshore basin in the The late early Permian (Shanxi period), and continental basin in the middle-late Permian (lower Shihezi-Shiqianfeng period). Final the author has discussed the sedimentary evolution and structure paleogeographic of different kinds of stages.Sixth, basing on outcrops and logging and seismic data, studying the development features of typical sedimentary environment. On the one hand, focusing on the mixed siliciclastic-carbonate sediments during late Carboniferous-early early Permian (Benxi-Taiyuan period). And analyzing the genetic mechanism and sedimentary characteristics of such kinds of sediments, identifing three main types of mixed sedimentary environment, which include the types of epeiric sea, barrier coast and shallow water delta. Fially, the mixed sediments model in Ordos basin is set. On the other hand, basing on analysis of genetic mechanism of shallow water deltas during late Paleozoic in Ordos basinis, analyzing sedimentary characteristics of them and identifing four main types of them, which include the types of gentle marine slope-type shallow meandering river delta (Taiyuan period), gentle river-tide controlled slope-type shallow braided river delta (Shan 2 period), transition phase slope-type shallow meandering river delta (Shan 1 period) and lacustrine slope-type shallow braided river delta(He 8 period). And studying the regulation and difference of such deltas, Fially, the sediments model of shallow deltas in Ordos basin is set.Seventh, basing on establishment of the sequence stratigraphy framework, determination of the conversions of marine-continental facies,analysis of the adjustment and disappearance of central paleouplift and segmentation of the sedimentary evolution of Ordos basin, discussing the regulation of sediments distribution and the process of sedimentation-sequence filling during late Paleozoic in Ordos Basin. It is based on super long term base-level cycle as a period, the sequence paleogeographic and sand isopach map during of lower Paleozoic in Ordos Basin were drew, which revealed the sediments distribution, the sedimentary evolution and sand distribution in different periods of late Paleozoic in Ordos Basin. On the base of the above analysis and sedimentation-sequence filling in different super long term base-level cycles, discussing the regulation and difference of sedimentary evolution of Ordos basin during late Paleozoic in Ordos Basin.更多还原