涠西南凹陷一号断裂陡坡带扇体沉积展布特征及主控因素

断裂陡坡带是沉积盆地重要的油气勘探区，对其扇体展布规律及其控制因素展开研究可揭示储层发育规律，指导油气勘探.综合利用录井、测井、三维地震资料，并结合区域轻重矿物、岩心沉积构造与粒度分析，对涠西南凹陷流一段沉积时期一号断裂陡坡带扇体的沉积类型及展布特征进行研究.结果显示陡坡扇体的发育具有明显分区性:陡坡西段发育大型下切沟谷，发育的扇体规模较大，呈不对称朵状，以粗粒的砂质碎屑流沉积为特征；陡坡中段发育带狭长水道的小型扇体，以发育悬移质为主的浊流沉积为特征；陡坡东段发育一系列小型沟谷水道及对应的对称状扇体.结合边界断裂活动、物源区母岩类型及古地貌分布特征分析，揭示了物源、构造、古地貌等要素对扇体的控制作用.陡坡西侧边界断裂活动较强、处于断层转换部位、物源供给充分，为大型粗质扇体形成提供条件；而陡坡中段与东段断裂活动和物源供给较弱、地形平缓，使其扇体发育规模相对较小. 

Sedimentary Architecture,Distribution Features and Genesis of Steep Slope Fan in Upper Liushagang Formation,Weixi'nan Sag

Using high quality 3D seismic data, combining analyses of light and heavy minerals, core observation and sand grain size distributions, sedimentary architecture and distribution features of steep slope fan in Upper Liushagang Formation of Weixi'nan Sag have been investigated in this study. These features vary along the NO.1 border fault:In the western part of steep slope belt, large-scale incised valleys developed, producing large-scale sub-lacustrine fans, which are characterized by thick beds of debris flow deposits; While in the middle part, small-scale channelized turbidite sub-lacustrine fans dominated; In eastern part, a series of small-scale symmetrical fans were located along the border fault, with sparse valleys present. Lateral variations of sediment supply, geomorphology and subsidence rate induced by multiple stages of border fault activity are considered the controlling factors:Fault slope in western part feeds coarser sediments from larger drainages. Meanwhile, large-scale incised valleys and complex morphology allow the growth of larger, asymmetrical fan lobes; On the other hand, fault slopes in the middle and eastern part with planar style and ramp-flat structure, respectively, provide a limited supply to multiple small fans.