【作者】 夏青松；

【导师】 田景春；

【作者基本信息】 成都理工大学 ， 沉积学， 2007， 博士

【摘要】 通过野外剖面观测、岩心描述，薄片鉴定和各种资料的综合分析，运用沉积学、石油地质学及地震地质学等理论对鄂尔多斯盆地南部上三叠统延长组长6-长8中的浊流和地震事件沉积进行了研究。本文对鄂尔多斯盆地南部上三叠统延长组长6-长8浊积岩的岩石类型，粒度特征，沉积构造特征进行了详细研究。研究表明长6-长8浊积岩的岩石类型为长石岩屑砂岩、岩屑长石砂岩和长石砂岩；浊积砂岩的矿物成熟度低，结构成熟度较低，杂基含量高。粒度分析表明为典型的浊流特征。沉积构造可见单一递变粒序、各种底层面构造、滑塌角砾和鲍马序列等、具有明显的韵律性和旋回性等。识别出薄层浊积岩、中层浊积岩、厚层浊积岩三种类型并描述其特征，主要为三角洲前缘滑塌浊积岩。在此基础上进行了亚相划分，详细描述了各亚相特征；确定了浊积岩分布在庆阳、合水、固城、安置农场、宁县及铜川地区。浊积岩的形成主要由外界的触发机制、充足的物源供给、古斜坡地形等因素控制。鄂尔多斯盆地南部中生界延长组长6—长8中发育与地震有关的震积岩。通过岩心观察和描述，对湖泊软沉积物的一些特殊构造进行了精细解释，识别出与古地震有关的软沉积物变形构造主要有微同沉积断裂、液化砂岩脉、振动液化卷曲变形构造、环状层理等。同时在塔17井中发现完整的震积岩垂向序列，据此建立了坳陷湖盆的震积岩垂向序列模式，序列自下而上分为下伏未震层、微断裂层、微褶皱层、碎块层及液化均一层，上覆未震层。定性讨论了震积岩特征与地震强度的关系及地震驱动与斜坡滑塌形成的变形构造之间的区别。该震积岩的发现为盆地构造演化提供了动力学解释，表明晚三叠世秦岭造山带南北向逆冲带的强烈活动，是本区延长组震积作用的直接诱发因素。同时该震积岩的发现，为盆地南部延长组长6—长8发育的大规模浊积岩的外界触发机制是由地震活动引起的提供了有力证据，还可以在更小的时间尺度内恢复盆地边界断裂的强烈活动性，对研究延长组时期的构造演化具有重要的科学意义。更多还原

【Abstract】 Having surveyed the field sections, cores of wells, observed manymicrostructures and analysed various relevant documents, with the guide of the theoryof sedimentology, petroleum geology and seismogeology, the paper reacher the eventsof turbidity and earthquake in the Chang6-Chang8 of Yanchang Formation, UpperTriassic, Ordos Basin.Types of petrology, characteristics of granularity, sedimentary structures ofturbidite of Chang6-Chang8 of the Yanchang Formation are researched. The turbiditeof Chang6-Chang8 mainly composed of lithic feldspathic sandstone, feldspathiclithic sandstone and feldspathic sandstone. Which have low compositional maturity,textural maturity and high matrix. The results of grain-size analysis show that thegrain-size parameters, distribution, compositions are evidently turbidite sediment.Sedimentary features observed in the cores include unidirectional graded sequence,burthen structures, fluidization structures, breccia, rhythm and cyclic sequence andBouma sequence. There are three type of turbidite which are lamina turbidite, mediumthickness turbidite and thick turbidite, they are mostly slumped turbidite from deltafront.Base on those characteristics, sedimentary faces are identified, The characteristicof sedimentary sub-facies are described detailed. It is confirmed that the distributionof turbidite is located in Qingyang, Heshui, Gucheng, Anzhinongchang, Ningxian,Tongchuan region. Outside trigger mechanism, enough sources and slope landform arethe most important conditions to form turbidite.Seismites were identified by soft-sediment deformational structures. Manyearthquake-related Seismites were discovered in the Chang6-Chang8 of theYanchang Formation. Having surveyed the cores of wells, many typical deformationstructures were discovered, Such as syn-sedimentary micro factures, stone veins, vibrational liquefaction, deformation structure, earthquake breccia and load-casts andballs-and pillows types, cyclic bedding etc. They were formed in const rained horizonsbounded by undeformed strata, suggesting that they are syndepositional. Thecomplete vertical sequence of seismite of Ta 17 well, which include shattered rock bed,ladder-shaped faulted bed, vibrational liquefaction deformation structure bed,liquefied sandstone vein bed, rubble bed and homogenized bed. The association isdiscussed between the character of seismites with earthquake intensity.Deformational structure of earthquake genesis is different from slump genesis.The discovery of seismit can be used to interpret the tectonic evolvement of thebasin. In Late Triassic, with the Closeing of Qinling and the sea slot of SouthernQilian, The south-north thrust band occurrence Strong activity. It was the directinducing factors of the seimo-deposition in Yanchang Formation.and provided theevidence for the turbidite of Chang6-Chang8 of the Yanchang Formation,southwestern Ordos Basin, the outsider trigger mechanism of the turbidite isearthquake activity.更多还原