Paleomagnetic Investigation of McMurdo Sound Region, Southern Victoria Land, Antarctica

• Main Author: Minoru Funaki
• Format: Report
• Language: English
• Published: National Institute of Polar Research 1984
• Subjects: Allan Hills; East Antarctica; McMurdo Sound; Victoria Land; Wright Valley; Antarc*; Antarctica; Geomagnetic Pole; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=646; http://id.nii.ac.jp/1291/00000646/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=646&item_no=1&attribute_id=18&file_no=1

A total of 602 rock samples for paleomagnetism were collected from the McMurdo Sound region, southern Victoria Land, Antarctica. These collected samples, ranging from the Cambro-Ordovician to the Cenozoic age, were examined using several tests of rock magnetism to check the evidence of stability of natural remanent magnetization (NRM) and were then studied paleomagnetically as follows : The samples of the Cenozoic volcanic rocks have stable NRM. The position of Antarctica has been almost the same from the late Pliocene age up to the present. The position of the virtual geomagnetic pole (VGP) (11 normals and 3 reverses) from the Pliocene age to the present is within a polar cap area of about 30 colatitude. The sequence of lava eruption was determined by synthetic evidence from paleomagnetic, geological and geochronological data. The almost samples of Ferrar dolerite of Jurassic age have stable NRM. All these samples were magnetized to the normal polarity, and the calculated VGP positions were 45.3°S, 152.0°W for the Wright Valley, 47.0°S, 133.2°W for the Allan Hills and 68.6°S, 139.5°W for Mt. Fleming. These VGP positions are in reasonablagreement with other Jurassic VGPs from Antarctica. The most samples of Beacon Supergroup have stable NRM of parallel direction to that of Ferrar dolerite. These samples were remagnetized in the Jurassic age and the primary magnetization disappeared. However part of the samples has stable depositional remanent magnetization of the Permo-Triassic age. The direction of NRM is parallel to that of Ferrar dolerite. East Antarctica had no shift from the Permo-Triassic to the Jurassic and Australia must have been linked to Antarctica at least up to the Jurassic age. The basement complex of Cambro-Ordovician age of Wright Valley has a stable component of NRM. The directions of NRM distributed on a meridian gathered gradually to low in latitude by thermal demagnetization up to 500℃, however distributed in high latitude dispersed by that demagnetization. These characteristics are related ...