Using a large number of core and and outcrop samples, and combining the drilling and logging data as well as la-boratory measurements, the relationship between the event deposits and the tight oil of Yanchang formation in southern Ordos Basin were systematically studied. The results show that there are four kinds of typical event deposits, including seismic, volcanic, anoxic and gravity flow deposit events. There are four typical combinations among these event deposits, in which the superposition of multi-stage sandy debris flow sandbody and turbidite is the most common type. Earthquakes and volcanos may induce turbidity flow, and subsequently form seismic turbidities. In addition, the combinations of oil shale, turbidite and tuff can be found clearly. The vertical model of event deposits and the typical sedimentary structure phenomena of seis-mites indicate that there were 5. 5-6. 5 magnitude earthquakes at Chang6 and Chang7 period in the study area. The event de-posit model indicates that the regions with delta front slope, semi-deep and deep lake is the most important area to record e-vent deposits. The slumping sand body in the delta front slope has the most plentiful records of event deposits. The seismic-turbidite mainly develops in deep lake area. High-quality source rocks caused by anoxic events are the source of tight oil;gravity flow sandbody is the important reservoir of tight oil; and seismic and volcanic events may improve tight reservoir. Sandy debris flow sandbodies are worth of great concern for their preferable properties and hydrocarbon potential.%根据大量的岩心观察、钻测井资料、野外剖面观测及分析化验资料,对鄂尔多斯盆地南部延长组事件沉积及与致密油的关系进行研究.结果表明:研究区主要存在地震事件、火山事件、缺氧事件和重力流沉积4种典型的事件沉积现象,对各个事件沉积的共生组合关系进行分析,发现主要存在4种典型的组合关系,其中深水重力流沉积中的多期砂质碎屑流及多期浊积岩的垂向叠置最为常见,地震、火山诱发浊流沉积形成震浊积岩,并可见油页岩与浊积岩和凝灰岩的组合配置关系;研究表明研究区在长6—长7期主要发生5.5~6.5级地震;三角洲前缘斜坡至半深湖—深湖区是记录事件沉积的重要区域,其中前缘斜坡坡脚处滑塌砂体的事件沉积记录最为丰富,深湖区是震浊积岩主要发育区域;缺氧事件形成的优质烃源岩是致密油藏的油源,重力流砂体是研究区致密油的重要储集层,同时地震事件及火山事件对储层也进行了有益的改造,砂质碎屑流沉积的储集层物性及含油性最好.
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