Geomagnetic Field Intensity Changes During the Last 3 Millennia in the Central Mediterranean (Greece and Italy).
Abstract
Archeointensity data obtained over the last decade have demonstrated that the geomagnetic field has exhibited numerous intense, short-lived (multidecadal), regional maxima in intensity at various times and locations. These intensity bumps, also called archeomagnetic spikes, have been clearly identified in different regions such as Western Europe or the Middle East. The origin of these peaks is a hot topic of debate nowadays since these features can provide important geophysical constraints to better understand the geodynamo behavior. For example, it is not clear if one of the most important intensity anomalies observed in the Levant during the last millennia (the LIAA) is a regional or a global feature of the geomagnetic field. However, the spatial and temporal variation of these intriguing features is not yet well understood mainly due to the scarcity of high-quality archeointensity data. In this context, we focus here on the study of past geomagnetic field intensity changes in the Central Mediterranean, a region for which high-quality archeointensity data are still scarce despite being a region with an important historical and cultural heritage. We present an archaeointensity study of several ceramics, kilns and bricks fragments collected from 12 archaeological sites (6 from Greece and 6 from Italy) with ages ranging between 1200 BC and 1600 AD. The samples were analyzed using the classical Thellier and Thellier method for paleointensity determination, including the correction of the anisotropy of the thermoremanent magnetization (TRM) and of the cooling rate dependence upon TRM acquisition. The accepted archeointensity results were obtained from one single component pointing through the origin in Zijderveld plots and linear Arai plots without any evidence of magnetochemical alteration. Furthermore, several rock-magnetic experiments were also carried out in order to identify the main magnetic carriers of the studied samples. The obtained data are compared with previously published archeointensities as well as with regional and global geomagnetic field models. This study contributes to better define different maxima and minima of intensity for these regions and, hence, to improve our understanding of past intensity changes in the Central Mediterranean.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP41A0762R
- Keywords:
-
- 1513 Geomagnetic excursions;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1521 Paleointensity;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1522 Paleomagnetic secular variation;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM