Using C-axis of quartz for determining deformation condition of Lakhshak granodiorite mylonites, NW of Zahedan, Iran



C-axis quartz measurement and petrography studies of Lakhshak granodiorite mylonite showed that most of the quartz grainshad recrystallized with grain boundary migration mechanism. This recrystall-ization tookk place over 630 ± 30?C temperatures. Most of the quartz crystals were deformed by prism [C] slip and maximum C-axis of the grains is closed X-axis on the stereogram. The prism [C] slip occurs over 550-600?C and presences water. Quartz was deformed during flatting ellipsoid stress and this situation caused that C-axes occur with girdles shape around stereogram Z axis. Opening angle of the C-axes girdles range from 79-114 that measured in The XZ plane through Z and using of Opening angle thermometer show that Lakhshak granodiorite mylonites were deformed at 585-730 ± 50?C. Based on the following evidences these rocks were deformed in presence of a little fluid: (1) replacement of plagioclase by intergrowth quartz and feldspar with granophyric texture,