Diformation Mechanisms of Hornblende of Amphibolite Facies in Guandi Complex, Zhoukoudian
|School||Chinese Geology University (Beijing)|
|Keywords||Zhoukoudian Guandi complex hornblende bulging recrystallization|
According to preexisted studies, this study carried out the field work on Archean amphibolites in Western Mountain, Beijing. And then, the optical microscope (OM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and electron probe microanalysis (EPMA) were applied to find out the deformation behavior and mechanisms of hornblende.It is observed that amphibolites deformed into mylonites by optical microscope. The hornblende developedσandδtype porphyroclast systems, and the new grains presented as a shape of needle.EBSD of porphyroclast and new grains revealed the same (100) <001> lattice preferred orientation (LPO), indicating the LPO of new grains inherited that of porphyroclasts.TEM images shown that the dislocation tangle appeared in middle of porphyroclast, dislocation array, dislocation wall, twinning and subgrain at margin of porphyroclast, and dislocation parallel to (110) prism in new grains.It is calculated that deformation occurred at 620~680℃, based on the study of plagioclase-hornblende geothermometry and geobarometry.Combined with the definition of bulging recrystallization, it could be concluded that the recrystallization mechanisms of hornblende should be bulging recrystallization.