EARLY DUCTILE SHEAR ZONE AND TECTONIC EVOLUTION IN THE MIDDLE SECTION OF LINHE-JINING DEEP FAULT, INNER MONGOLIA

The deep fault from Linhe to Jining, a complex long_term active fault zone has not been under thorough investigation in terms of its early evolution for the past years. However, in the present research, five tectonic sections in the proportion 1:2 000 are mapped on the basis of the 1:50 000 regional geological surveying. In addition, a great number of micro-structural observations and fabric measurements are completed in the laboratory. The research shows that the evidence of the Neo-Archaean fault is expressed by the high-temperature ductile shear zone of high amphibolite facies-granulite facies that is overprinted by the low-temperature ductile shear zone of the greenschist in the shallow layers after the Lower Proterozoic crust was elevated in the extension system. After the Middle Proterozoic, this ductile shear zone is transformed into brittle fault, controlling deposition and magma formation in different periods.