Paleointensity Estimates from the Pleistocene of Northern Israel:
Implications for hemispheric asymmetry in the time averaged field
Abstract
Twenty-two sites, subjected to an IZZI-modified Thellier-Thellier
experiment and strict selection criteria, recover a paleomagnetic axial
dipole moment (PADM) of 62.24$\pm$ 30.6 ZAm$^2$ in
Northern Israel over the Pleistocene (0.012 - 2.58 Ma). Pleistocene data
from comparable studies from Antarctica, Iceland, and Hawaii,
re-analyzed using the same criteria and age range, show that the
Northern Israeli data are on average slightly higher than those from
Iceland (PADM = 53.8 $\pm$ 23 ZAm$^2$, n = 51
sites) and even higher than the Antarctica average
%\cite{asefaw21} (PADM = 40.3 $\pm$
17.3 ZAm$^2$, n = 42 sites). Also, the data from the Hawaiian drill
core, HSDP2, spanning the last half million years (PADM = 76.7
$\pm$ 21.3 ZAm$^2$, n = 59 sites) are higher than
those from Northern Israel. These results, when compared to Pleistocene
results filtered from the PINT database (www.pintdb.org) suggest that
data from the Northern hemisphere mid-latitudes are on average higher
than those from the southern hemisphere and than those from latitudes
higher than 60$^{\circ}$N. The weaker intensities
found at high (northern and southern) latitudes therefore, cannot be
attributed to inadequate spatio-temporal sampling of a time-varying
dipole moment or low quality data. The high fields in mid-latitude
Northern hemisphere could result from long-lived non-axial dipole terms
in the geomagnetic field with episodes of high field intensities
occurring at different times in different longitudes. This hypothesis is
supported by an asymmetry predicted from the Holocene, 100 kyr, and five
million year time-averaged geomagnetic field models.