title: Weaker axially dipolar time-averaged paleomagnetic field based on multidomain-corrected paleointensities from Galapagos lavas.
abstract: The geomagnetic field is predominantly dipolar today, and high-fidelity paleomagnetic mean directions from all over the globe strongly support the geocentric axial dipole (GAD) hypothesis for the past few million years. However, the bulk of paleointensity data fails to coincide with the axial dipole prediction of a factor-of-2 equator-to-pole increase in mean field strength, leaving the core dynamo process an enigma. Here, we obtain a multidomain-corrected Pliocene-Pleistocene average paleointensity of 21.6 ± 11.0 µT recorded by 27 lava flows from the Galapagos Archipelago near the Equator. Our new result in conjunction with a published comprehensive study of single-domain-behaved paleointensities from Antarctica (33.4 ± 13.9 µT) that also correspond to GAD directions suggests that the overall average paleomagnetic field over the past few million years has indeed been dominantly dipolar in intensity yet only ∼ 60% of the present-day field strength, with a long-term average virtual axial dipole magnetic moment of the Earth of only 4.9 ± 2.4 × 10(22) A ⋅ m(2).
authors.affiliation: Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854;
authors.forename: Huapei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964; dvk@rutgers.edu.
authors.forename: Dennis V
authors.initials: DV
authors.lastname: Kent
authors.affiliation: Aix-Marseille Université, CNRS, IRD, CEREGE UM34, 13545 Aix en Provence, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Rochette
keywords: Thellier paleointensity experiment; geomagnetism; multidomain correction; paleomagnetism; time-averaged dipole field