Earth Planets Space, Vol. 60 (No. 9), pp. e13-e16, 2008E-LETTER
Masao Ohno1, Fumi Murakami1, Fumiki Komatsu1, Yohan Guyodo2, Gary Acton3, Toshiya Kanamatsu4, Helen F. Evans5, and Futoshi Nanayama6
1Department of Environmental Changes, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka 810-8560, Japan
2Laboratorie des Sciences du Climat et de l'Environnement, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
3Department of Geology, University of California, Davis, Davis, CA 95616, USA
4Deep Sea Research Department, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan
5Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120, USA
6Institute of Geology and Geoinformation, Geological Survey of Japan, AIST, Ibaraki 305-8567, Japan
(Received April 4, 2008; Revised August 23, 2008; Accepted August 25, 2008; Online published September 26, 2008)
The geomagnetic field direction during the Gauss-Matuyama (G-M) polarity transition was investigated from a high-accumulation-rate (≥10 cm/kyr) sediment core drilled in the Gardar drift in the North Atlantic at Site U1314 during Expedition 306 of the Integrated Ocean Drilling Program (IODP). A well-defined characteristic remanent magnetization was generally obtained by alternating field demagnetization. The consistency of the results with records from Icelandic lavas confirms that the North Atlantic drift sediments contain a high-fidelity record of the geomagnetic field change. During the G-M transition, the virtual geomagnetic pole (VGP) latitude shows north-south-north-south rebounding, with the three VGP paths falling within different longitudinal bands. Two of the three paths are close to or within the preferred bands in which transitional VGPs are suggested to be longitudinally confined. Three additional loops occur that approach mid-to-low latitudes from the North or South pole regions. In addition, the VGPs show rapid movement (directional jumps) between VGP clusters.
Key words: Geomagnetism, polarity transition, Integrated Ocean Drilling Program, Expedition 306, Site U1314.