【摘要】 砂砾岩扇体是胜坨地区沙三下亚段最重要的沉积体系,形成于坡度陡、物源近、构造活动强烈的深湖环境。根据岩心观察并结合地震、测井等资料,识别出了近岸水下扇及与之相关的重力流水道和滑塌浊积扇沉积。近岸水下扇多夹于暗色泥岩之中,垂向上具有向上变细的正旋回特征,平面上主要分布于陈南断层东段下降盘,根部紧贴基岩断面。重力流水道岩性主要为暗色泥岩夹砾岩和砾状砂岩,反映了块体搬运的特征,垂向上缺乏浊积扇的扇相层序。滑塌浊积砂体具线状物源,缺乏主水道,岩性较细,部分砂层发育典型的鲍马层序。各沉积体系的形成受构造特征、古地貌和物源区性质等因素的影响,断裂活动十分活跃,是该区复合沉积体系形成的决定性因素。更多还原

【Abstract】 The sand-conglomerate fans are the major depositional systems in the lower third member of Shahejie Formation in Shengtuo area,which formed in the deep lacustrine environment characterized by steep slope gradient,near sources and intensive tectonic activity.The near-shore subaqueous fans and its relative gravity channel and fluxoturbidite fan depositions were identified according to observation and description of cores combined with the numerous data of seismic and logging.The near-shore subaqueous fans mainly mingled within dark mudstones and located on the downcast side of the east Chennan fault in the horizontal direction.The grain size of the near-shore subaqueous fans became smaller from bottom to top in vertical direction.The bottom of those fans closely attached to the basement.The gravity channels and fluxoturbidite fans developed simultaneously.The gravity channels are the dark mudstones mingled with conglomerate and sandy conglomerate.The turbidity fan sequences are absent in the vertical direction.The fluxoturbidite fans have the linear provenance and fine grain size.The major channels are absent.The classic Bouma sequences developed in partial sandstones.The structural feature,palaeogeomorphology and provenance controlled the depositional system.The intense fault activity is the crucial factor for the formation of the complex depositional systems.更多还原