Natural remanent magnetization of the Napier Complex in Enderby Land,East Antarctica

Abstract

Paleomagnetic studies were performed with the oldest rocks reported (about 3800 m.y.), collected from the Napier Complex in East Antarctica. Five specimens have stable NRM against AF and thermal demagnetizations, but other five have unstable one. The main NRM carriers in the former specimens are pure magnetite of single-pseudosingle domain structure. The Napier Complex was remagnetized completely in the amphibolite facies metamorphism 2500 m.y. ago. Since the cooling rate of the Complex was very slow at that time, it recorded the changing geomagnetic field. The most reliable NRM direction obtained is -82.9°inclination and 39.3°declination by thermal demagnetization to 480℃, and the corresponding VGP position is calculated to be latitude 75.0°S and longitude 14.5°E.