The gypsum-and halite-bearing rock series of the Dingyuan Formation of Tertiary System at the north fringe of the Hefei rifted basin can be divided into three stages,i.e.

• 合肥断陷盆地北缘古近、新近系含膏,含岩盐系可分为三个阶段:即早期为成膏,成盐准备阶段;中期为成膏,成盐强烈阶段;晚期为成膏,成盐消亡阶段。