松辽盆地南部十屋断陷层沉积体系类型及特征

The deposition system analysis of Shiwu rifted stratum in the south of Songliao basin

十屋断陷为一西断东超的箕状断陷,桑树台断裂是主要的控盆断裂,控制了十屋断陷的形成与演化,控制了断陷沉积层序的岩性特征及时空分布特征,在靠近断裂一侧,沿陡坡快速堆积了冲积扇、水下扇、扇三角洲等粗碎屑沉积物,向断陷中心迅速过渡为半深湖—深湖沉积,并伴有深水浊流沉积。在断陷缓坡带,水体变浅,沉积物减薄,沉积相由半深湖—深湖相逐渐转变为滨浅湖、扇三角洲相及河流相。断陷两侧沉降深度差异较大,形成不对称式充填。此外,断陷北侧的端部存在较大的物源,形成纵向扇三角洲朵体。

The prospecting degree in the Shiwu rifted basin is relatively low now, and the distribution of oil and gas is rather complex, but researches in recent years indicate Shiwu fault stratum have good prospect of oil and gas. The Shiwu rift is a dustpaned rift which is faulted in the west but overlapped in the east. The Sangshutai fault is the main controlling fault. It has controlled the formation and the evolution of Sbiwu rift, and controlled characteristics of the lithology and spatial distribution in rifted stratum. Near the side of the rupture, it fast piled up the alluvial fan, the sublacustrine fan and the fan delta along the steep slopes. While in the center of the rifted basin, it rapidly deposited semi--deep lake facies, and accompanied by the deep water turbidite. In gentle slope belt, the depth of water changes shallow, and the deposition decreases and the semi--deep lake facies gradually transformed into the shore shallow lake, the fan delta and the river facies. The subsidence depth in both sides of the rift has a great difference, so forms the antisymmetrical filling. Besides, there is a big source in the north of the rift basin, and a vertical fan delta is formed.