特征
含腕足类、牙形石、珊瑚、蜓类等化石。
下部产腕足类:Phricodothyris asiatica,Neochonetes carboniferous,Marginifera pulcher等;牙形石:Declinognathodus lateralis,Idiognathoides sinuata;珊瑚:Fomitchevella orientalis longiseptata,Paracarruthersella abnormis;中部含蜓:Profusulinella wangyui,Pseudostaffella jomdaensis,Schubertella gracilis znensis;珊瑚:Petalaxis sp.,Paracarruthersella simplex,Arctophyllum intermedium,Amygdalophylloides gracilis,Fomichevella orientalis;牙形石:Idiognathoides sinuatus,Streptognathodus parvus;腕足类:Reticularia novosemelica;上部含丰富的蜓:Fusulinella biconica,F.pseudobocki,Fusulina sp.,Pseudostaffella sphaeroidea;腕足类:Choristites gigans,Buxtonia giganta;牙形石:Idiognathodus delicatus,I.humerus。
下部为台地边缘浅滩相沉积;中部水体平静,为开阔海台地,低能相沉积;上部属开阔海台地浅滩相沉积。与下伏岩口组和上覆支沟组均为整合接触。厚344米。