Abstract
Using the most recent global database of paleomagnetic directions for the past 4 Myr we have tested whether the far-sided effect of Wilson (1970, 1971) remains a stable feature of the time-averaged field. We found out that this characteristic persists for all sub-time intervals as well as for different sites distributions. The U-shaped pattern of the mean inclination anomaly (deviation from the inclination of the axial dipole) as a function of latitude is described by a small quadrupole contribution that amounts 5% of the dipole. There is no need for other terms which in any case cannot be properly described given the overall dispersion of the data. We have analyzed the evolution of the quadrupole/dipole ratio for periods characterized by different mean axial dipole strength using composite curves of relative paleointensity. We report that periods of weaker dipole field are effectively characterized by a larger mean inclination anomaly and thus by a larger quadrupole/dipole ratio. We infer that the mean value of the inclination anomaly could potentially be an indirect indicator of the mean dipole strength.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Carlut J, Courtillot V (1998) How complex is the time-averaged field over the past 5Myr? Geophys J Int 134:527–544
Cox A, Doell RR (1960) Review of paleomagnetism. Geol Soc Am Bull 71:645–768
Channell JET, Xuan C, Hodell DA (2009), Stacking paleointensity and oxygen isotope data for the last 1.5 Myr (PISO-1500). Earth Planet Sci Lett 283:14–23
Gubbins D, Kelly P (1993) Persistent patterns in the geomagnetic field over the past 2.5 Myr. Nature 365:829–832
Hospers J (1954). Rock magnetism and polar wandering. Nature 173:1183
Irving E (1964) Paleomagnetism and its application to geological and geophysical problems. Wiley, New York, NY
Johnson CL, Constable CG (1995) The time-averaged geomagnetic field as recorded by lava flows over the past 5 Myr. Geophys J Int 122:489–519
Johnson CL, Constable CG (1997) The time-avergaed field: global and regional biases for 0–5 Ma. Geophys J Int 131:643–666
Johnson CL et al (2008) Recent investigations of the 0–5 Ma geomagnetic field recorded by lava flows. Geochem Geophys Geosyst 9:Q04032. doi:10.1029/2007GC001696
Lund SP, Banerjee SK (1985) Late quaternary paleomagnetic field secular variation from two Minnesota lakes. J Geophys Res 90:803–825
McElhinny MW (2004) The geocentric axial dipole hypothesis: a least squares perspective. In: Channell JET, Kent DV, Lowrie W (eds) Timescales of the internam geomagnetic filed. American geophysical union monograph, vol 145. pp 1–12
McElhinny MW, Lock J (1995) Four IAGA databases released in one package. Eos Trans AGU 76:266
McElhinny MW, Merrill RT (1975) Geomagnetic secular variation over the past 5 my. Rev Geophys 13:687–708
McElhinny MW, McFadden PL, Merrill RT (1996) The time averaged paleomagnetic field 0-5 Ma. J Geophys Res 101:25007–25027
McFadden PL, Merril RT, McElhinny MW (1988), Dipole/quadrupole family modelling of paleosecular variation. J Geophys Res 93:11,583–11,588
Merrill RT, McElhinny MW (1977) Anomalies in the time- averaged paleomagnetic field and their implications for the lower mantle. Rev Geophys Space Phys 15:309–323
Merrill RL, McElhinny MW, McFadden PL (1996) The magnetic field of the earth: paleomagnetism, the core and the deep mantle. Academic
Quidelleur X et al (1994), Long-term geometry of the geomagnetic field for the last 5 million years: an updated secular variation database from volcanic sequences. Geophys Res Lett 21:1639–1642
Schneider DA, Kent DV (1990) The time-averaged paleomagnetic field. Rev Geophys 28:71–96
Valet J-P (2003) Time variations in geomagnetic intensity. Rev Geophys 41:1/1004
Valet JP, Meynadier L, Guyodo Y (2005) Geomagnetic dipole strength and reversal rate over the past two million years. Nature 435:802–805
Wilson RL (1970), Permanent aspects of the Earth’s non-dipole magnetic field over tertiary times. Geophys J R Astron Soc 19:417–439
Wilson RL (1971) Dipole offset – the time average paleomagnetic field over the past 25 million years. Geophys J R Astron Soc 22:491–504
Acknowledgements
Financial support to J-P Valet and L. Meynadier was provided through the CNRS-INSU Interieur de la Terre Program, IPGP contribution # 3011. Financial support to E.H-B was provided by SOEST-HIGP and by the National Science Foundation grants EAR-0510061, EAR-0710571, EAR-1015329, and NSF EPSCoR Program. This is a SOEST 1145 and HIGP 1888 contribution.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2011 Springer Science+Business Media B.V.
About this chapter
Cite this chapter
Valet, JP., Herrero-Bervera, E. (2011). Time-Averaged and Mean Axial Dipole Field. In: Petrovský, E., Ivers, D., Harinarayana, T., Herrero-Bervera, E. (eds) The Earth's Magnetic Interior. IAGA Special Sopron Book Series, vol 1. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-0323-0_9
Download citation
DOI: https://doi.org/10.1007/978-94-007-0323-0_9
Published:
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-007-0322-3
Online ISBN: 978-94-007-0323-0
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)