SUPERPLASTIC DEFORMATION OF ROCKS AND ITS DYNAMIC IMPLICATIONS

This paper mainly reviews deformation mechanism of superplasticity,microstructural aspects and its dynamic implications. Superplasticity of rocks, an important kind of rock deformation,refers to the phenomenon of some rocks exhibiting an unusual large tensile deformation without necking failure( e 1 000% ).According to deformative factors,it can be divided into structural superplasticity and transformational superplasticity.While superplasticity is not a simple deformation mechanism, but rather a deformation phenomenon.It is closely related with diffusion creep and dislocation creep,and it is the result of the competition of diffusion accommodated grain boundary sliding and dislocation creep.Study on superplastic deformation of rocks has significant implications for formative mechanism of mylonites, origin of deep seismic reflector near the Moho of the lower crust, rheological weakening of upper mantle, and occurrence and abrupt stop of deep earthquakes.