Paleomagnetic study of marine sediments from Antarctic Sea-Central Wilkes Land margin, Dumon d'Urville Sea and Victoria Land Basin-

概要

論文の詳細を見る
Paleomagnetic study is conducted on sediment cores from the Antarctic Ocean off the Central Wilkes Land margin, the Dumont d'Urville Sea and Victoria Land Basin The Brunhes/Matuyama geomagnetic polarity boundary (B/M boundary, 0 78 Ma) and the Jaramillo geomagnetic event (0 99-1 07 Ma) are identified in five cores at the Central Wilkes Land margin One core from the Victoria Land Basin shows the B/M boundary The assigned magnetostratigraphical age indicates the sedimentation rate of between 3 and 5 mm/ky The susceptibility variation with depth is studied The upper sequence younger than 0 4 Ma shows variation with larger amplitude than that of the lower sequence, however, the average and frequency dependence of susceptibility do not show distinct changes This suggests a change of sedimentary environment around 0 4 Ma, which may be correlated with the global climate change The magnetic intensity normalized by susceptibility shows a distinct decrease around B/M boundary, the intensity is higher in the Brunhes epoch than that in the Matuyama epoch The result is similar to the variation of geomagnetic dipole moment studied by J P VALET and L MEYNADIER (Nature, 366, 234, 1993) on the ODP cores from the Pacific Ocean This suggests that there was a global change of geomagnetic field intensity, between the Matuyama reversed epoch and the Brunhes normal epoch
国立極地研究所の論文