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西北地区侏罗系广泛发育扇三角洲、辫状河三角洲和曲流河三角洲相沉积。其中扇三角洲与陡倾的盆地边缘有关,盆地的沉降速率大于沉积速率,沉积层序为加积型,并以沉积物重力流和无河道片流共同搬运的沉积物短暂泄荷为特征。辫状河三角洲与不很陡的盆地边缘梯度有关,其沉积速率大于盆地的沉降速率,沉积层序为进积型,并以河道径流广泛发育为特征。曲流河三角洲与缓坡拗陷型构造边界有关,并具有以河流作用为主,湖泊作用为辅的特征。3种三角洲具有良好的储集油气潜能,是西北地区侏罗系油气勘探的重要目标。
In the northwestern Jurassic extensive fan delta, braided delta and meandering delta deposits are developed. The fan delta is related to the steeply dipping basin margin. The sedimentation rate of the basin is greater than the sedimentation rate. The sedimentary sequence is accretion type, and is characterized by the transient discharge of sediments co-transported by sediment gravity flow and no-river flow. Braided river delta is related to the steep basin edge gradient, its sedimentation rate is higher than that of the basin, sedimentary sequence is progressive type and characterized by extensive river runoff. The Meandering Delta is related to the gently sloping depression tectonic boundary and has the characteristics of mainly river and supplemented by lakes. The three kinds of delta have good hydrocarbon accumulation potential and are an important target of petroleum exploration in the Jurassic in northwestern China.