MIKROSTRUKTUR DAN DEFORMASI BATUAN METAMORF DAERAH BARRU PROVINSI SULAWESI SELATAN

A microstructure and deformation studies have been conducted on metamorphic rocks in the Barru area which is focus on recrystallisation textures of quartz and orientation of porphyroblast aggregate. Petrographic and crystallographic preferred orientation (CPO) of quartz which are determined by manual universal stage method (U-Stage) were performed to determine deformation evidence of metamorphic rocks in this study. Recrystallisation evidence consist of two characterizations namely subgrain rotation (SGR) and bulging (BLG) as indicated at low temperature deformation, but sometime its shown a static recrystallisation texture that indicates only caused by temperature during deformation and metamorphism. Preferred orientation of quartz [C] axis showing operated near to Z axis (60%) and near to X axis (40%) in stereographic lower hemisphere projection. Orientation of quartz [C] axis near to Z axis of stereogram indicates that deformation was occurred at low temperature metamorphism and quartz [C] axis operated near to X axis indicated high temperature conditions. They are still contentious that caused the deformation at high temperature conditions since it is inconsistent with conditions of metamorphism facies which is generally a lower amphibolite to greenschist facies. Orientation of porphyroblats in metamorphic rocks in the Barru area is generally dextral sense of shear and seems to be consistent with the results of orientation of crystallographic preferred orientation of quartz [C] axis in stereogram???s. In addition, textures and orientations of porphyroblats represent intertectonic to syntectonic deformation. Based on deformation textures above, it can be conclude that the metamorphic rocks in the area were occurred in single phase of metamorphism with more than one deformation phase