A ductile shear zone developed around the Ranba dome in the eastern part of northern Himalayan dome belt. Various mylonites were formed in this ductile shear zone, in which the quartz was one of the major rock-making minerals. Different microstructures developed in the quartz under different temperatures and strain rates, among which dynamic recrystallization was the most common structure. The shapes of recrystallized quartz grains with their jagged and indented boundaries were natural records of deformation conditions. Fractal analysis showed that the boundaries of recrystallized grains had statistically self-similarities with the numbers of fractal dimension from 1.14 to 1.19. From these numbers, deformation temperature was about 500℃, similar to that of middle or high green-schist grade metamorphism. Paleo-strain rates were deduced to be not more than 10-9.5S-1, and the paleo-stress was calculated with grain size of recrystallized quartz to be 6.2～58.8 MPa.
Zhang Bo,Zhang Jinjiang,Guo Lei. FRACTAL ANALYSIS OF DYNAMICALLY RECRYSTALLIZED QUARTZ GRAINS AND ESTIMATION OF MAINLY RHEOLOGICAL PARAMETERS OF THE RANBA DUCTILE SHEAR ZONE, NORTHERN HIMALAYAN DOME BELT[J]. Chinese Journal of Geology, 2006, (1): 158-169.