资源环境科技发展态势分析平台

Recent archaeomagnetic data from ancient Israel revealed the existence of a so-called "Levantine Iron Age geomagnetic anomaly" (LIAA) which spanned the first 350years of the first millennium before the Common Era (B.C.E.) and was characterized by a high averaged geomagnetic field (virtual axial dipole moments, VADM>140ZAm(2), nearly twice of today's field), short decadal-scale geomagnetic spikes (VADM of 160-185ZAm(2)), fast field variations, and substantial deviation from dipole field direction. The geographic constraints of the LIAA have remained elusive due to limited high-quality paleointensity data in surrounding locations. Here we report archaeointensity data from Georgia showing high field values (VADM>150ZAm(2)) in the tenth or ninth century B.C.E., low field values (VADM<60 ZAm(2)) in the twelfth century B.C.E., and fast field variation in the fifth and fourth centuries B.C.E. High field values in the time frame of LIAA have been observed so far only in three localities near the Levant: Eastern Anatolia, Turkmenistan, and now Georgia, all located east of longitude 30 degrees E. West of this, in the Balkans, field values in the same time are moderate to low. These constraints put geographic limits on the extent of the LIAA and support the hypothesis of an unusually intense regional geomagnetic anomaly during the beginning of the first half of the first millennium B.C.E., comparable in area and magnitude (but of opposite sign) to the presently active South Atlantic anomaly.