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二连盆地乌里雅斯太凹陷下白垩统发育一套典型的湖底扇沉积,其由补给水道、内扇、中扇和外扇4个部分组成,主要发育有补给水道,内扇主沟道和沟堤,中扇辫状沟道、沟道间和外扇席状浊积砂等微相类型。湖底扇单个扇体规模不大,但往往多期次发育、成群分布,垂向上相互叠置、横向上叠加连片,规模可观。足够的可容纳空间和持续的物源补给是形成厚层湖底扇的2个重要条件,同沉积断裂的下降盘和坡折带是湖底扇发育的有利部位。湖底扇砂砾岩体具有毗临生油洼槽、易于形成岩性圈闭、易于油气聚集等优越条件,对岩性油气勘探具有重要意义。
In the Lower Cretaceous of the Urias Depression of Erlian Basin, a typical sublacustrine fan is developed. It consists of four parts: recharge channel, inner fan, middle fan and outer fan. The main development is recharge water channel, inner fan main channel And ditch embankment, fan-braided trench, channel and outer fan-like turbid sand and other microfacies type. The single fan body of the sublacustrine fan is not large in scale, but often develops in multiple stages and is distributed in groups and vertically stacked on top of each other. Sufficient space for accommodation and continuous supply of source materials are two important conditions for forming thick lacustrine fans. The descending plate and slope break zone of the same depositional faults are favorable sites for the development of the sublacustrine fan. The fan-conglomerate body at the bottom of the lake has favorable conditions such as the Plinux oil-producing depression, easy lithologic trap formation and easy oil and gas accumulation, and is of great significance to lithologic hydrocarbon exploration.