Paleointensity Estimates From the Pleistocene of Northern Israel: Implications for Hemispheric Asymmetry in the Time-Averaged Field

Twenty-two sites, subjected to an IZZI-modified Thellier-Thellier experiment and strict selection criteria, recover a paleomagnetic axial dipole moment (PADM) of 62.2 +/- 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 +/- 23 ZAm(2), n = 51 sites) and even higher than the Antarctica average (PADM = 40.3 +/- 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 +/- 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 () 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 degrees N. The weaker intensities found at high (northern and southern) latitudes therefore, cannot be attributed to inadequate spatiotemporal 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 5 million year time-averaged geomagnetic field models.

Automated summary

Using a modified Thellier-Thellier experiment and strict selection criteria, this study found that the Pleistocene paleomagnetic axial dipole moment in Northern Israel is slightly higher than that of Iceland and even higher than that of Antarctica. The data from the Hawaiian drill core also showed higher values compared to Northern Israel. Furthermore, the results suggest that the average paleomagnetic intensity in mid-latitude Northern Hemisphere is higher than that of the Southern Hemisphere and latitudes higher than 60 degrees N. These findings indicate that the weaker intensities found at high latitudes cannot be attributed to inadequate sampling or low-quality data, and could be due to long-lived non-axial dipole terms in the geomagnetic field.