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AGU: Geophysical Research Letters

 

Keywords

  • paleointensity
  • secular variation
  • inclination anomaly

Index Terms

  • Geomagnetism and Paleomagnetism: Paleomagnetic secular variation
  • Geomagnetism and Paleomagnetism: Paleointensity
  • Geomagnetism and Paleomagnetism: Time variations: secular and longer
  • Geomagnetism and Paleomagnetism: Spatial variations: all harmonics and anomalies

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L20307, 5 PP., 2008
doi:10.1029/2008GL035373

Geomagnetic field variations during the last 400 kyr in the western equatorial Pacific: Paleointensity-inclination correlation revisited

Toshitsugu Yamazaki

Geological Survey of Japan, AIST, Tsukuba, Japan

Toshiya Kanamatsu

Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan

Sakiko Mizuno

Center for Advanced Marine Core Research, Kochi University, Kochi, Japan

Natsumi Hokanishi

Geological Survey of Japan, AIST, Tsukuba, Japan

Eddy Z. Gaffar

Research Center for Geotechnology, Indonesian Institute of Science, Bandong, Indonesia

A paleomagnetic study was conducted on four piston cores newly obtained from the West Caroline Basin in the western equatorial Pacific in order to investigate variations in paleointensity and inclination during the last 400 kyr. An inclination-intensity correlation was previously reported in this region using giant piston cores, but the quality of the paleomagnetic data of the younger end, the last ca. 300 kyr, was needed to be checked because the upper part of the giant piston cores could suffer from perturbation by oversampling. Age control is based on the oxygen-isotope ratios for one core and inter-core correlation using relative paleointensity for other cores. Stacked curves of paleointensity and inclination were constructed from the four cores. It was confirmed that variations on the order of 104 to 105 years occur in inclination as well as paleointensity. A cross-correlation analysis showed that significant in-phase correlation occurs between intensity and inclination for periods longer than about 25 kyr, and power spectra of both paleointensity and inclination variations have peaks at ∼100 kyr periods. The regional paleointensity stack with higher resolution than the Sint-800 stack (Guyodo and Valet, 1999) should be useful for paleointensity-assisted chronostratigraphy.

Received 22 July 2008; accepted 19 September 2008; published 24 October 2008.

Citation: Yamazaki, T., T. Kanamatsu, S. Mizuno, N. Hokanishi, and E. Z. Gaffar (2008), Geomagnetic field variations during the last 400 kyr in the western equatorial Pacific: Paleointensity-inclination correlation revisited, Geophys. Res. Lett., 35, L20307, doi:10.1029/2008GL035373.

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