【作者】 陈全红；

【导师】 李文厚；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2004， 硕士

【摘要】 在构造演化上鄂尔多斯盆地南部继承整个盆地的特点。晚三叠世—中侏罗世，印支运动特提斯板块向北或北北东方向的运动，在右行剪切力的作用下，西部泾川一带出现一南北向隆起，东部铜川—黄陵一带出现一南北向凹陷；延长组沉积时为半潮湿气候环境。盆地南部延长组的沉积就是在上述区域地质背景下形成的。 盆地南部延长组厚度一般为400～1400m，总体呈现为西薄东厚，北薄南厚的特点。在延长组的划分和对比过程中，遵循寻找全区分布比较稳定的5个主要标志层和1个辅助标志层。先对大段，再对小段，旋回控制，参考厚度等原则，从下到上可分为10个油层组。 盆地南部在延长组沉积时东、西、南地势低平，其沉积过程经历了湖盆发育初期的平原河流环境—中期的湖泊环境—晚期的三角洲环境和泛滥平原—河流平原环境三个阶段，以河流和三角洲相沉积为主，中东部拗陷幅度较大，为湖相沉积，在深湖地带常有浊流沉积。本文根据岩石类型、沉积结构、构造、古生物、沉积旋回、岩电组合、野外露头、测井资料及地震分析等多种手段，识别出鄂尔多斯盆地南部上三叠统主要由冲积扇体系、河流沉积体系、湖泊沉积体系、三角洲沉积体系组成，并进一步分为14种亚相，24种微相，而且详细研究了研究区的深湖浊流、三角洲沉积等亚相，提出它们在盆地南部的模式。 详细分析了延长组不同时期沉积相带在平面上的分布，并利用三角洲平原相与前缘相的界线、高岭石含量在滨湖带的富集来确定湖岸线位置。 盆地南部重矿物组合主要分为两种类型。西南物源和东北物源是研究区继承性好，持续时间长的重要物源区。中部的华池、合水、固城川地区重矿物组合变化大，种类繁多，在相当长的时间内很明显是一个混合带，受各个方向物源的综合影响；富县地区延长组REE地球化学特征及REE分配模式曲线与盆地东北缘太古代及早元古代变质岩一致，而且，镇泾地区和盆地东北缘变质岩REE分配模式也基本一致，说明鄂尔多斯地区在太古代及早元古代为一统一的基底，只是西南及东北构造演化的过程不同，证明了它们物质来源都基本继承了原始物质的特征。 层序地层学研究时主要利用地层接触关系、相旋回特征和相的突变界面、区域性特征界面(最大湖泛面)、河道砂体的叠置方式以及区域较好的对比标志层识别层序界面。通过对对应基准面转换点的河流—三角洲—湖泊沉积体系中相序与相组合的变化、单一沉积微相沉积特征的垂向变化、旋回叠加样式的改变和地层几何形态与接触关系的研究，发现准层序在盆地南部可分为向上变细准层序、向上变粗准层序、复合型准层序，进而分析了研究区加积准层序组、退积准层序组及进积准层序组的特点与空间分布特征，概述了低位早期体系域、低位晚期体系域以及高水位体系域特点及在不同层序的发育及空间分布特征。在上述分析的基础上，划分延长组为一个构造超层序和长10—长9、长8—长7、长6—长4+5和长3+2—长1四个三级沉积层序，认为层序地层形成的主导因素是构造运动，分析了层序地层和油气的关系，认为层序控制了生储盖组合、储层的展布及储层的储集性能。更多还原

【Abstract】 On the tectonic evolvement, the south of ordos basin inherited the whole basin characteristic that pale-tectonical movements resembled in the early-middle Trias period and the Permain period. Late Triassic-Middle Jurassic epoch, Indosinian movement tethys plate moved to northward or north-northeast. Under the right lateral shear force, Jingchuan area of the west of basin appeared a north-northeast doming, but Tongchuan - huangling area appeared a north-south depression. The circumstance was half-humidity weather when Yangchang formation began to sediment. The sediment of south Ordos basin was formed in this regional geological background.In the south of Ordos basin, the thickness of Yangchang formation changed from 400m to 1400m, which generally had appeared that the western was thin but the eastern was chick, and that the northern was thin but the southern was chick. However, the partition and contrast of Yanchang formation followed and searched 5 pieces of primary markers and one pieces of assistant marker where the Yangchang formation distributing was more steady in research area, and the stratum could be divided into ten pieces of member following the principles that firstly contrasting the bag segments, then contrasting the small segments, being controlled by cycle and consulting the thickness, etc.The hypsography was low and plain in the south of Ordos basin when Yangchang formation began to deposit. The process of sediment come through three processes that was plain-river environment in the early lake basin development era, lake environment in the metaphase era and the delta and the flood plain-river plain environment in the late era. The main was river and delta facies environment sediment. In the middle and east district where the depression was bag and the environment was deep lake that frequently broke out turbidity current. This thesis identified the upper Triassic be composed mainly by alluvial fan, river, lake and delta sedimentary system, and farther distinguished those sedimentary system, then divided carefully them into 14 types sediment subfacies and 24 types sediment microfacies. After carefully researched the subfacies like deep lake turbidity current and delta sediment, those modes had been put forward.Based on using the borderline between the delta plain and the delta front facies, and analyzing Kaolinite content that was enriched in bank zone to confirm the situation of lake strandline, had carefully confirmed the ichnographic lake strandline distributing and sedimentary facies zone in different period.In the south of Ordos, the basin heavy mineral association mainly was divided into two types.The southwest and the northeast provenance was the important provenance district that had good inheriting characters and affected for a long time. But in Huachi, Heshui and Guchengchuan, the heavy mineral association was various and changed extraordinarily great, and in a long time, there obviously was a commixing belt that had been synthetically affected by all other various provenances. The upper Triassic in Fuxian area, the geochemistry characters and the distributing mode of REE curve was consistented with the Archaean and the early Proterozoicmetamorphic rock. But in Zhenjing area, the REE distributing mode of REE curve also resembled the metamorphic rock in the northeast of Ordos area, which indicated that the Ordos area was a unitive basement in the Archaean and the early Proterozoic era. The only difference was the process of the tectonic evolvement of the southwest and the northeast part of Ordos area. Accordingly, these proved all their provenances inherited the characters of the original mother roch, then discussed the provenance evolvement.Based on utilizing the stratum touching relations, the characters of facies cycle, the abrupt interface of facies, the regional characteristic interface (the maximum lake flooding surface), and the river channels sand’s overlapping fashion and the regional good contrasting markers, the sequence interfaces had been identified after researching the更多还原