Archaeointensity determinations from Italy: new data and the Earth's magnetic field strength variation over the past three millennia

Tema, Evdokia; Goguitchaichvili, Avto; Camps, Pierre

doi:10.1111/j.1365-246x.2009.04455.x

Cited by 16 publications

(14 citation statements)

References 56 publications

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“…7; all data were reduced to the latitude of Thessaloniki, 40.65°N). The data are mainly ($85%) from Bulgaria (Kovacheva et al, 2014) but also from Greece and Southern Italy (Evans, 1986;Aitken et al, 1988Aitken et al, , 1989Tema et al, 2009;Spassov et al, 2010;Spatharas et al, 2010;Kondopoulou et al, 2014). The NRMS of 2.40 ± 1.60 indicates that the model could not fit a significant number of data with their a priori errors.…”

Section: Geomagnetic Field Intensity Variations In Western Europe Ovementioning

confidence: 99%

“…Chauvin et al, 2000;Genevey and Gallet, 2002). Despite recent and significant improvements (Donadini et al, 2008(Donadini et al, , 2012Gallet et al, 2009;Tema et al, 2009;Gómez-Paccard et al, 2012), this period remains poorly documented, which penalizes the construction of accurate regional and/or global archeomagnetic field models (e.g. Pavón-Carrasco et al, 2014a,b).…”

Section: Introductionmentioning

confidence: 98%

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New archeointensity data from French Early Medieval pottery production (6th–10th century AD). Tracing 1500 years of geomagnetic field intensity variations in Western Europe

Genevey

Gallet

Jesset

et al. 2016

Physics of the Earth and Planetary Interiors

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a b s t r a c tNineteen new archeointensity results were obtained from the analysis of groups of French pottery fragments dated to the Early Middle Ages (6th to 10th centuries AD). They are from several medieval ceramic production sites, excavated mainly in Saran (Central France), and their precise dating was established based on typo-chronological characteristics. Intensity measurements were performed using the Triaxe protocol, which takes into account the effects on the intensity determinations of both thermoremanent magnetization anisotropy and cooling rate. Intensity analyses were also carried out on modern pottery produced at Saran during an experimental firing. The results show very good agreement with the geomagnetic field intensity directly measured inside and around the kiln, thus reasserting the reliability of the Triaxe protocol and the relevance of the quality criteria used. They further demonstrate the potential of the Saran pottery production for archeomagnetism. The new archeointensity results allow a precise and coherent description of the geomagnetic field intensity variations in Western Europe during the Early Medieval period, which was until now poorly documented. They show a significant increase in intensity during the 6th century AD, high intensity values from the 7th to the 9th century, with a minimum of small amplitude at the transition between the 7th and the 8th centuries and finally an important decrease until the beginning of the 11th century. Together with published intensity results available within a radius of 700 km around Paris, the new data were used to compute a master curve of the Western European geomagnetic intensity variations over the past 1500 years. This curve clearly exhibits five intensity maxima: at the transition between the 6th and 7th century AD, at the middle of the 9th century, during the 12th century, in the second part of the 14th century and at the very beginning of the 17th century AD. Some of these peaks are smoothed, or nearly absent when the selection of the data is extended to a 1250 km radius around Paris. The apparent regularity in the occurrence of intensity maxima, with a recurrence of $250 years, is particularly intriguing and might reflect a new characteristic of the secular variation, at least in Western Europe. It clearly requires further investigation and in particular the acquisition of new data from older periods.

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Section: Geomagnetic Field Intensity Variations In Western Europe Ovementioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

New archeointensity data from French Early Medieval pottery production (6th–10th century AD). Tracing 1500 years of geomagnetic field intensity variations in Western Europe

Genevey

Gallet

Jesset

et al. 2016

Physics of the Earth and Planetary Interiors

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“…As for western Europe only data derived from Thellier derived experiments and including pTRM checks have been retained. A total of 42 data from Bulgaria (N ¼33, Kovacheva et al, 2009a), Greece (N ¼6, De Marco et al, 2008;Spatharas et al, 2000Spatharas et al, , 2011Tema et al, 2012) and Italy (N ¼3; Leonhardt et al, 2006;Tema et al, 2010) have been selected and relocated to the latitude of Sofia through the VADM (Fig. 7b).…”

Section: Geomagnetic Field Intensity Changes In Eastern Europe Betweementioning

confidence: 99%

Improving our knowledge of rapid geomagnetic field intensity changes observed in Europe between 200 and 1400 AD

Gómez‐Paccard

Chauvin

Lanos

et al. 2012

Earth and Planetary Science Letters

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a b s t r a c tAvailable archaeomagnetic data indicate that during the past 2500 yr there have been periods of rapid geomagnetic field intensity fluctuations interspersed with periods of almost constant field strength. Despite Europe being the most widely covered region in terms of archaeomagnetic data the occurrence and the behaviour of these rapid geomagnetic field intensity changes is under discussion and the challenge now is to precisely describe them. The aim of this study is to obtain an improved description of the sharp intensity change that took place in western Europe around 800 AD as well as to investigate if this peak is observed at the continental scale. For this purpose 13 precisely dated early medieval Spanish pottery fragments, four archaeological French kilns and three collections of bricks used for the construction of different French historical buildings with ages ranging between 335 and 1260 AD have been studied. Classical Thellier experiments performed on 164 specimens, and including anisotropy of thermoremanent magnetisation and cooling rate corrections, gave 119 reliable results. The 10 new high-quality mean archaeointensities obtained confirm the existence of an intensity maximum of $ 85 mT (at the latitude of Paris) centred at $ 800 AD and suggest that a previous abrupt intensity change occurred around 600 AD. Together with previously published data from western Europe that we deem to be the most reliable, the new data also suggest the existence of two other abrupt geomagnetic field intensity variations during the 12th century and around the second half of the 13th century AD. High-quality archaeointensities available from eastern Europe indicate that very similar geomagnetic field intensity changes occurred in this region. European data indicate that very rapid intensity changes (of at least 20 mT/century) took place in the recent history of the Earth's magnetic field. The results call for additional high-quality archaeointensities obtained from precisely dated samples and for a selection of the previously published data if a refined description of geomagnetic field intensity changes at regional scales is to be obtained.

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“…1). For the region centred at Sabra al-Mansuriya, all data come from Italy (see the compilations of Tema et al 2006Tema et al , 2010 except the one located at Libya (Odah et al 1995). For the region centred at Sabra al-Mansuriya, all data come from Italy (see the compilations of Tema et al 2006Tema et al , 2010 except the one located at Libya (Odah et al 1995).…”

Section: Comparison With Other Available Archaeomagnetic Datamentioning

confidence: 99%

“…Tanguy et al 2003;Tema et al 2006). The archaeomagnetic compilations of Donadini et al (2009) andGenevey et al (2008) have been supplied with recent data (Ben-Yosef et al 2008;Casas et al 2008;Catanzariti et al 2008;De Marco et al 2008;Donadini et al 2008Donadini et al , 2010Gómez-Paccard et al 2008;Herries et al 2008;Peters et al 2008;Ruiz-Martinez et al 2008;Sapin et al 2008;Suteu et al 2008;Tema & Lanza 2008;Gallet et al 2009;Genevey et al 2009;Hartmann et al 2009;Kovacheva et al 2009a;Márton 2009Márton , 2010Nachasova & Burakov 2009;Schnepp et al 2009;Tema et al 2010). The location of the archaeomagnetic sites is plotted in Fig.…”

Section: Comparison With Other Available Archaeomagnetic Datamentioning

confidence: 99%

Archaeomagnetic and rock magnetic study of six kilns from North Africa (Tunisia and Morocco)

Gómez‐Paccard¹,

McIntosh²,

Chauvin³

et al. 2012

Geophysical Journal International

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International audienceNew full-vector archaeomagnetic data for North Africa recovered from the study of six kilns, five from Tunisia and one from Morocco, are presented. Archaeological and historical considerations, along with three radiocarbon dates, indicate that the age of the kilns ranges between the 9th and 15th centuries AD. Rock magnetic analyses showed that the principal magnetic carriers are magnetite and low Ti titanomagnetite, along with variable contributions of thermally stable maghemite and a high coercivity phase with low unblocking temperatures. The magnetic mineralogy of the studied material is thermally stable and behaves ideally during archaeointensity experiments. Stepwise alternating field demagnetization isolated a single, stable, characteristic remanence component with very well defined directions at both specimen and structure levels. Mean archaeointensities have been obtained from successful classical Thellier experiments conducted on between five and eight independent samples per kiln. Thermoremanent magnetization (TRM) anisotropy and cooling rate effects upon TRM intensity have been investigated. The results showed that these effects are low for four of the six studied kilns, with differences between the uncorrected and corrected means of less than 3 per cent. For the other two structures differences between the uncorrected and corrected mean site intensities are 4.4 per cent and 5.8 per cent. These results highlight the necessity for TRM anisotropy and cooling rate corrections in archaeomagnetic studies if accurate archaeointensities are to be obtained. The new results suggest that high intensities occurred in Northwest Africa during the 9th century. Although more data are clearly needed to define this period of high intensity, the results are in agreement with the available European archaeointensity data. Acomparison between the newdata, other available archaeomagnetic determinations in nearby locations, and palaeosecular variation (PSV) curves derived from the regional SCHA.DIF.3k and global ARCH3K.1 geomagnetic field models shows good agreement between the new data and directional results derived from the models. However, some differences are observed between geomagnetic field models intensity results and available archaeointensity data for the studied regions. This highlights the need for new data for unexplored regions such as North Africa. The new data presented here better constrains the evolution of the geomagnetic field during historical times in this region. They represent a new step towards the construction of a reference PSV curve for Northwest Africa. Once established, this curve will represent a new dating method for this region

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Archaeointensity determinations from Italy: new data and the Earth's magnetic field strength variation over the past three millennia

Cited by 16 publications

References 56 publications

New archeointensity data from French Early Medieval pottery production (6th–10th century AD). Tracing 1500 years of geomagnetic field intensity variations in Western Europe

New archeointensity data from French Early Medieval pottery production (6th–10th century AD). Tracing 1500 years of geomagnetic field intensity variations in Western Europe

Improving our knowledge of rapid geomagnetic field intensity changes observed in Europe between 200 and 1400 AD

Archaeomagnetic and rock magnetic study of six kilns from North Africa (Tunisia and Morocco)

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