THE SEQUENCE AND AGE OF THE ZHONGTIAOSHAN METAMORPHIC ROCK SERIES

The assignment of the Sushui complex and stratigraphic correlation of the Songjiashan Groupare two basic problems on the metamorphic rock series in the Zhongtiao Mountains. Proceedingfrom a new understanding of the phases of deformation- metamorphism and nature of contact rela-tionships of various rock series through field surveys, it has been ascertained preliminarily thatthe Sushui complex is the product of the Jiangxian movement and its subsequent thermal eventand that the Songjiashan Group might be older than the Jiangxian Group or both might be syn-chronous but heteropic. Comparison of different samples from various rock series in terms of dif-ferent measuring means,geological settings and age data suggests that the upper limits of the agesof the Danshanshi Group,Zhongtiaoshan Group,Jiangxian Group/Songjiashan Group and HupingGroup are 1.5,2.0,2. 5 and 2. 8 Ga respectively.