They are late Cretaceous epoch stage(K2), Palaeocene-Eocene epoch stage(E(subscript 1-2)), Oligecene-Miocene epoch stage(E3-N1), and Paliocene-Quaternary period stage(N2-Q).

• 其中每一阶段依据古构造、古水文地质图及古气候特徵，将盖层后生改造作用划分还原型和氧化型两种基本类型。