In the late Carboniferous, rift bay deposit occurred in Helanshan, while widespread epicontinental sea deposit developed in the area east of paleo-mid-ridge.

• 中二叠世早期，研究区由北向南依次为冲积扇、辫状河、辫状河三角洲平原、辫状河三角洲前缘和滨浅湖所占据。