EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Yamazaki & Oda 2005
Yamazaki, T. and Oda, H. (2005). A geomagnetic paleointensity stack between 0.8 and 3.0 Ma from equatorial Pacific sediment cores. Geochemistry Geophysics Geosystems 6: doi: 10.1029/2005GC001001. issn: 1525-2027.

We have conducted a paleomagnetic study of six sediment cores taken from the equatorial Pacific, three from the West Caroline Basin and three from the Manihiki Plateau, in order to make a relative paleointensity stack during the Matuyama and late Gauss Chrons. The age of the bottom of the cores ranges from 1.2 to 3.0 Ma. The sediments show little downcore changes in the proxies of magnetic grain size and mineralogy and are hence suitable for estimating relative paleointensity. The age of the cores is controlled by correlating variations in magnetic concentration (magnetic susceptibility and/or anhysteretic remanent magnetization (ARM)) to target oxygen-isotope (δ18O) curves. All cores from the Manihiki Plateau show an upward decrease of the natural remanent magnetization (NRM) intensity normalized by ARM and isothermal remanent magnetization (IRM) with a decrease in sedimentation rate. Such a trend was removed before being converted to relative paleointensity. This observation implies that a sedimentation-rate change can affect relative paleointensity estimation. Relative paleointensity records from the six cores coincide well with each other within uncertainty of age. We constructed a stacked curve between 0.8 and 3.0 Ma (the equatorial Pacific paleointensity stack EPAPIS-3Ma) after adjusting age; the number of cores stacked is three to four throughout the record. Quasiperiodic paleointensity lows occur in the EPAPIS-3Ma, and corresponding paleointensity lows can be found in previously published records with some shifts in age. At least, parts of the paleointensity minima seem to be accompanied by geomagnetic excursions. The "asymmetric sawtooth pattern" of paleointensity variations is not observed at the Matuyama-Gauss boundary and thereafter in our record. A spectral analysis shows that ~100 kyr orbital eccentricity frequency may exist in paleointensity variations during the Matuyama and late Gauss Chrons.

DATABASE QUICK LINKS

MagIC Database

BACKGROUND DATA FILES

Abstract

MagIC SmartBook v1
MagIC SmartBook v2
MagIC SmartBook v3
MagIC SmartBook v4
MagIC SmartBook v5
MagIC SmartBook v6

Keywords
Geomagnetism and Paleomagnetism, Geomagnetic excursions, Geomagnetism and Paleomagnetism, Paleointensity, Geomagnetism and Paleomagnetism, Instruments and techniques, equatorial Pacific, excursion, orbital modulation, paleointensity, paleomagnetism
Journal
Geochemistry Geophysics Geosystems
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit