Paleomagnetic studies of the Archean rocks collected from the Napier Complex in Enderby Land,East Antarctica

Abstract

A total of 10 Archean rocks, collected from the Napier Complex in Enderby Land, Antarctica, were studied paleomagnetically. Natural remanent magnetization (NRM) of 5 specimens is stable supported by AF and thermal demagnetization of NRM, magnetic hysteresis and AF demagnetization of SIRM and ARM properties. The magnetic carriers in the specimens are estimated to be magnetite of single-/pseudosingle-domain structures associated with a small amount of pyrrhotite. However, other 5 specimens have only unstable NRM due to pseudosingle-/multi-domain structures. The VGP position, 75.0°S latitude and 14.5°E longitude, is calculated from the stable NRM component (-82.9°inclination, 39.3°declination and 8.2°α_ value) which is obtained from thermal demagnetization at 480℃. This NRM was acquired at the final metamorphism (2.45-2.5 b.a.) through a cooling stage from 580 to 480℃. The VGP position is very different from apparent polar wander paths around 2.5 b.a. of Piper's Pangaea, Australia and Africa. If the determination of NRM acquisition age is reliable, it suggests the continental rearrangements between the Pangaea of 2.5 b.a. and the early stage of Gondwanaland.