Abstract:

Tectonic gneiss is one of main tectonites in ductile deformation belt of deep tectonic levels of crust, which record a lots of important information for rock rheological characteristics and being developed in Precambrian high grade metamorphic rocks. Tectonic gneiss is a dynamic tectonite, which is formed by strongly plastic rheology, metamorphism and partial melting, has evidently plastic rheological characteristic in macroscopic structures, but no reduction of grain size in microscopic textures. It characters dense bands and gneissosity in outcrop and sample scale, triple side equilibrium texture in microscopic scale. One of main factors which controlled and affected the formation of the tectonic gneiss is melt，main deformation mechanism are diffusion creep and grain flow, causing huge strain in deformed rocks, but no strain in single grain. Tectonic gneiss zone can be divided into three different types: bedded tectonic gneiss zone of syn-metamorphism, liner and network tectonic gneiss zone of retrogressive metamorphism.

Key words: tectonic gneiss, tectonic levels, rheology, melt, tectonite, tectonics