1.The middle oil-member is characterized by medium-sized sandstone and pebbled sandstone, with fair sorting and subangular sphaericity.Rock types mainly were feldspar debris sandstone.

1.中油组主要沉积中砂和含砾中砂，较粗，分选性较好，磨圆以次棱角状为主，石类型为长石屑砂。