Seven kinds of clastic sedimentary systems are developed in Es 3 and Es 4 of Gubei subsag, which are dominated by alluvial fan, fan delta and sublacustrine fan.

• 孤北洼陷沙三、四段主要发育七种碎屑岩沉积体系,以冲积扇、扇三角洲和湖底扇为主。