Zonal distributien can be noticed in gossan resulted from siderite in carbonate strata, and this can be accounted for by zoning Of ground water. Because siderit
Pb isotopic ages of some Precambrian rooks from North China were measured. Some new data from the Chuanlingkou Formation of thel Great Wall Group in Yenshan reg
Five stages can be recognized with respeet to the evolution of the Jilin meteorite in the light of preliminary results available: (1) The stage of birth, fracti