SYNCHRONOUS SYNTECTONIC GRANITE EMPLACEMENT IN THE SOUTH PALMER RIVER REGION, HODGKINSON PROVINCE, AUSTRALIA

Deformation partitioning in pluton wall-rocks during granite intrusion that is synchronous with regional tectonism potentially creates structures suggesting different timing of emplacement. This is due to variations in style and intensity of fabric development, particularly porphyroblast-matrix microstructures. In the South Palmer River region, detailed mapping plus microstructural examination of matrix and porphyroblast-matrix relationships assist correlation of deformation elements across variations in deformation style and intensity. The results indicate that the emplacement of each granite body occurred during the compressional Permian D4 event. The fabrics that developed regionally and in the pluton/wall-rock systems during D4 show differing degrees of intensity and style, which are spatially related to the intensity of D4 fabric development in the adjacent country rock. Granite isotopic ages support non-diachronous formation of D4 structures across the region.