Persistently anomalous Pacific geomagnetic fields

Citation:
Johnson, CL, Constable CG.  1998.  Persistently anomalous Pacific geomagnetic fields. Geophysical Research Letters. 25:1011-1014.

Date Published:

Apr

Keywords:

core-mantle boundary, earths core

Abstract:

A new average geomagnetic field model for the past 3kyr (ALS3K) helps bridge a large temporal sampling gap between historical models and more traditional paleomagnetic studies spanning the last 5 Myr. A quasi-static feature seen historically in the central Pacific has the opposite sign in ALS3K; its structure is similar to, but of larger amplitude than, that in the time-averaged geomagnetic field for the last 5 Myr. Anomalous geomagnetic fields exist beneath the Pacific over timescales ranging from 10(2)-10(6) years. It is unlikely that bias over such long time scales arises from electromagnetic screening, but conceivable that the Lorentz force is influenced by long wavelength thermal variations and/or localized regions of increased electrical conductivity (associated with compositional anomalies and possibly partial melt). This is consistent with recent seismic observations of the lower mantle.

Notes:

n/a

Website

DOI:

10.1029/98gl50666