METAMORPHIC CORE COMPLEXES AND EARLY CRETACEOUS RIFTING IN TRANSBAIKALIA

Abstract

The concept of metamorphic core complexes is applied for the first time to explain the nature of granite gneiss domes in Transbaikalia instead of the commonly used idea of their formation during granitization. Analysis of geological and geophysical data showed that the granite gneisses 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 jutting dates from the Early Cretaceous on the basis of the available K-Ar ages of granitoids and parallelism in geometry between the domes and the Early Cretaceous rift basins.