Tectonics and Metamorphism of the Region around Lutzow-Holmbukta, East Antarctica

• Main Author: Masaru Yoshida
• Format: Report
• Language: English
• Published: Department of Geosciences, Faculty of Science, Osaka City University 1979
• Subjects: East Antarctica; Ongul; Skallen; Antarc*; Antarctica; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1016; http://id.nii.ac.jp/1291/00001016/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1016&item_no=1&attribute_id=18&file_no=1

Reviewing recent studies of the region around Lutzow-Holmbukta, the scheme of the superposing tectonics and metamorphism is summarized in chronological order as follows. 1) Formation of the Skallen and Ongul groups of the southern part of the region, in the age considerably earlier than 1100 Ma. 2) The D_1 tectonics of earlier nappe and later isoclinal folds with axes trending nearly parallel to the coast line of Lutzow-Holmbukta, associated with the M_1 high pressure granulite facies metamorphism with the P-T conditions around 880℃-13.5kb. 3) Formation of the Okuiwa group of the northern part of the region. 4) The M_2 intermediate pressure granulite facies metamorphism with the P-T conditions around 880℃-8.8kb, in the age around 1100Ma. 5) The D_2 tectonics of open to close folds with axes trending east-west, associated with the M_8 high grade amphibolite facies metamorphism with the P-T conditions around 680℃-5.5kb, dominating the northern part of the region. 6) The D_8 tectonics of gentle folds with axes trending nearly north-south and faults of the similar trend, associated with the intrusion of pink granites and the late phase of the M_8 low grade amphibolite facies metamorphism with the P-T conditions around 520℃-3.8kb, in the age around 400Ma. 7) The M_4 greenschist facies or slightly lower grade metamorphism. 8) The D_4 tectonics of conjugate shear fractures with acute bisectrix in the east-west direction indicating the northerly extensional stress field; the stress field is probably attributed to the beginning of the Gondwana dispersion which occurred during the Mesozoic era.