METAMORPHIC CORE COMPLEXES AND EARLY CRET ACEOUS RIFTING IN TRANSBAIKALIA

The concept of metamorphic core complexes is applied for the first tim e to explain the nature of granite gneiss domes in Transbaikalia inste ad of the commonly used idea of their formation during granitization. Analysis of geological and geophysical data showed that the granite gn eisses and mylonites of the domes make up laminas which were formed in bottom walls of shallow normal faults with these walls jutted out of mid-crustal level in the process of extension. The latest episode of j utting dates from the Early Cretaceous on the basis of the available K -Ar ages of granitoids and parallelism in geometry between the domes a nd the Early Cretaceous rift basins.