【摘要】 鄂尔多斯盆地长7油层组广泛发育大规模重力流沉积砂体,对盆地周缘露头及几百口井取心井进行了系统沉积相综合研究。研究结果表明,长7油层组沉积期,湖盆西南及湖盆中部重力流沉积主要为滑塌、砂质碎屑流和浊流,以砂质碎屑流沉积为主;在纵向上,砂质碎屑流沉积和浊流沉积不同组合的多期叠置形成了6种纵向组合类型,并在平面上呈一定的规律性分布;受沉积底形控制,在斜坡区以砂质碎屑流沉积为主,顺斜坡呈带状分布,平面分布规模小;在湖盆中部的坡脚及湖底平原,由于能量减弱,沉积物大量沉积,形成以砂质碎屑流为主的大规模重力流沉积,构成湖盆中部砂体的主体;再往湖盆中心,则主要发育薄层的浊流沉积。成因分析认为,盆地西南较陡的湖盆底形、细粒沉积物的高速率供应和高频次地震促发是重力流砂体发育的重要条件。更多还原

【Abstract】 The large scale of sand bodies of deep-water gravity flows are developed in Chang7 Reservoir of TriassicYanchang Formation in Ordos Basin.By researching the outcrop and hundreds of drilling corings,an integral study is systematically carried out in sedimentary facies.The result indicates that the sand deposits of deep water gravity flow of Chang7 can be subdivided into slump,sandy debris flow and turbidty flow,in which the sandy debris flow deposits are the main type and the turbidites take second place.The different ways of stacking of the sandy debris flows deposits and turbidites can form 6 styles of vertical architecture,which are regularly distributed in the plane.Controlled by sedimentary bottom shape,in the slope area,debris are the main styles and are banded along the slope.Its distributional scale is relatively small in plane.On the foot of slope and the lake floor plain,owing to the reduction of hydropower,the sedimentations are discharged greatly and formed large scale of gravity flow sedimentation,which mainly are sandy debris flow.It also are the mainly composition of the sand bodies in the center of the basin.Forward to the center of basin,the turbid current deposits of thin layers are mainly developed.The genesis analysis indicates that the high-rate supply of basin-bottom type,fine-grained sediments and high-frequency sub-seismic acceleration are an important condition for the development of gravity-flow sand bodies in the deeper slope area in the southwest of the basin.更多还原