【作者】 范萌萌；

【导师】 李文厚；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2010， 硕士

【摘要】 在综合前人研究成果和已有勘探资料的基础上,以沉积学的基本原理和方法为指导,综合构造-地层分析、地球物理学、地球化学、盆地分析、古地貌恢复等多种理论和方法,通过野外露头、钻井、测井等资料的综合分析,研究了鄂尔多斯盆地东南部上三叠统延长组的物源方向、沉积相类型和沉积相展布规律。在延长组的划分和对比过程中,寻找全区分布稳定的4个主要标志层和2个辅助标志层。遵循先对大段,再对小段,旋回控制,参考厚度等原则,从下到上可划分为9个油层组。依据野外剖面露头观察、岩心描述、单井相分析和连井剖面对比,结合岩石类型、沉积结构、构造、古生物、沉积旋回等多种手段,识别出研究区上三叠统延长组主要发育湖泊沉积相和三角洲沉积相,并进一步分为4种亚相,10种微相。在区域地质背景、轻重矿物、古流向及稀土元素分析的基础上,延长组存在东北部和南部两大物源,其中东北部物源来源于盆地北缘的阴山、大青山地区的太古界乌拉山群和下元古界二道凹群中的深变质结晶片岩、片麻岩,南部物源来源于盆地南缘秦岭区古隆起的变质岩系和上、下古生界的浅海相碎屑岩及碳酸盐岩。研究区延长组主要发育东北、南部两大沉积体系,均以三角洲沉积相为主。沉积相平面展布特征控制砂体展布,东北部砂体连片性好,以席状、朵状为主,呈北东向展布；南部砂体形态为条带状,呈近南北向展布。延长组沉积过程经历了湖盆发育初期的平原河流,中期的湖泊环境,晚期的泛滥平原至湖泊消失三个阶段。更多还原

【Abstract】 Based on the previous research results and exploration data and guided by fundamental sedimentological theory and means, the paper studies the source direction, sedimentary facies types and distribution of sedimentary facies of Upper Triassic Yanchang Formation in the southeast part of Ordos Basin on the basis of geophysics, geochemistry, basin analysis and ancient landscape restoration, combined outcrops, cores and well logging data.In the course of the partition and contrast of Yanchang formation,4 primary marker beds and 2 assistant marker beds are searched firstly, which distribute steadily in the whole area. The stratum could be divided into nine oil layers, following the principles that contrasting the big sections firstly, then small sections, being controlled by cycle, consulting the thickness, etc.Based on outcrop observation, core description, single well facies and comparison of connecting-well sections, combined with rock type, sedimentary texture, structure, paleontology, sedimentary cycle, etc, the paper points out that the main facies developed in study area of Upper Triassic Yanchang Formation are lake facies and delta facies, which can further devided into 4 types of subfacies and 10 types of microfacies.On the basis of regional geologic background, light and heavy minerals, palaeocurrent and rock trace element characteristics, the paper believes that Yanchang Formation has the northeast and south provenances. The northeast one was from deep metamorphic schist and gneiss of Archean Wulashan Group and Lower Proterozoic Erdaoao Group of Yinshan and Daqingshan area in the north border of Ordos Basin. The south one was from metamorphic rock of palaeohigh and shallow marine clastic rock and carbonate rock of Upper and Lower Paleozoic in Qinling region, the south border of Ordos Basin.In study area, there are two main sedimentary systems in the northeast and the south. Both of them are delta facies. The distribution of sedimentary facies controlled the distribution of sand body. The northeast sand body has a good connectivity and presents silllike and northeast-southwest distribution. The south sand body is banded and nearly north-south distribution. The deposition of Yanchang Formation went through three stages: the plain-river environment in the early development of basin, lake environment in metaphase and flood plain in the last when the lake disappeared.更多还原