Geomagnetic Field Intensity Behavior in South America Between 400 AD and 1800 AD

GRECO, CATRIEL; GOGUICHAISHVILI, AVTO

San Francisco, California

Congreso; Fall Meeting, AGU 2010; 2010

American Geophysical Union

An absolute archeointensity study in Northwest Argentina provided 25 independent geomagnetic field lectures supported by 37 radiometric dates between AD 400 and 1800. The mean archeointensity values obtained in this study range from 36.5 to 63.1 microT, with corresponding Virtual Axial Dipole Moments (VADMs) from 7.4 to 12.7 (10E22 Am2). Most of data are concentrated between a relatively narrow interval from 1350 AD to 1550 AD. Three general features may be detected: the time intervals from about AD 1150 to 1350 and 1450 to 1600 are characterized by quite monotonic decay of geomagnetic intensity while some increase is observed from AD 1600 to 1700. The archeointensity decrease from about seventeenth century seems to be a general characteristic of global geomagnetic field because it was observed at different places worldwide. In absence of reliable climate variation record for South America it is delicate to make any firm conclusions about the relationship between the Earth?s magnetic field and multi-decadal climatic events. However, it is probably not a coincidence that persistent warm climate detected from Patagonia during AD 1200 to 1350 is consistent to geomagnetic intensity decrease revealed in this study.