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Absolute palaeointensity determination is a long-winded and complicated procedure. The Thellier-Thellier technique, in particular, requires multiple heating and cooling steps. Magnetic minerals are often chemically unstable, and multiple... more
Absolute palaeointensity determination is a long-winded and complicated procedure. The Thellier-Thellier technique, in particular, requires multiple heating and cooling steps. Magnetic minerals are often chemically unstable, and multiple heatings may cause oxidation, hence aiding the subsequent neo-formation of remanence carriers during the procedure. Samples from recent rhyodacitic lava flows on Santorini (Southern Greece)and archaeological material (burnt clay) from two Hellenistic pottery kilns at Katerini (Northern Greece) have been tested for their thermal stability. Small specimens were used to study the temperature dependence of magnetic low-field susceptibility, using a Thellier-Thellier like measurement sequence. The remanence properties were tested on palaeomagnetic standard sized samples by detailed alternating field (AF) demagnetisation of isothermal remanent magnetisation (IRM) and IRM acquisition at different annealing temperatures. The coercivity content was analysed ...
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The ground magnetic measurements in Albania were used for the compilation of the Total Magnetic Field (TMF) anomaly map of Albania. The magnetic data were processed and interpreted in order to study the structure of the ophiolitic belts... more
The ground magnetic measurements in Albania were used for the compilation of the Total Magnetic Field (TMF) anomaly map of Albania. The magnetic data were processed and interpreted in order to study the structure of the ophiolitic belts of Albania. The ophiolites of Albania are placed at the Mirdita zone and are divided into two parallel alignments which are called the eastern and western ophiolitic belts. They are associated with strong potential field anomalies and their characteristics are considered crucial for a better understanding of the tectonic settings of Albania. The ground TMF data used in this study were acquired over various campaigns (1990-1994) and cover most of Albania's territory. The data were compiled to a map after reduction to the epoch 1990.4. The strongest magnetic anomalies in Albania appear along the known ophiolitic belts which trend NE-SW to the north and NW-SE to the south. Several processing steps were applied to the unified and gridded data in orde...
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Four sites in 1.4 Ma old basaltic lavas and two sites in upper Pliocene-lower Quaternary sediments, located both in the hanging-wall and in the footwall blocks of the Nea Anchialos Fault System, have been sampled. This fault system is one... more
Four sites in 1.4 Ma old basaltic lavas and two sites in upper Pliocene-lower Quaternary sediments, located both in the hanging-wall and in the footwall blocks of the Nea Anchialos Fault System, have been sampled. This fault system is one of the major E-W trending structures affecting the Thessaly region during Quaternary times.It is possibly connected with the North Aegean Trough to the E and displays recent seismic activity (1980, Volos earthquake). Standard techniques have been used for both field sampling and laboratory analyses. The magnetic carriers were characterised by measuring the thermomagnetic curves, the anisotropy of magnetic susceptibility and the isothermal remanent magnetisation of the samples. Almost all the samples exhibit a reverse polarity. The overall mean paleomagnetic direction is defined by D = 174°, I = 54°, confirming the non-rotational deformation pattern of the Nea Anchialos Fault System as independently inferred from structural investigations.
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... Herbert Haubold1, Robert Scholger1, Despina Kondopoulou2 & Hermann J. Mauritsch1 1 Paleomagnetic Laboratory 'Gams', Montanuniversität Leoben, Gams 45, A ... according to another model, this tectonic contact is not... more
... Herbert Haubold1, Robert Scholger1, Despina Kondopoulou2 & Hermann J. Mauritsch1 1 Paleomagnetic Laboratory 'Gams', Montanuniversität Leoben, Gams 45, A ... according to another model, this tectonic contact is not interpreted as a Neogene low-angle nor-mal fault, but as ...
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A total of 64 Greek archaeomagnetic directional data have been used for the establishment of the variation of the Earth's magnetic field in Greece over the past 4500 years. Most of the data come from archaeological material but some... more
A total of 64 Greek archaeomagnetic directional data have been used for the establishment of the variation of the Earth's magnetic field in Greece over the past 4500 years. Most of the data come from archaeological material but some data from Santorini lava flows are also included. The data ages range from Minoan times (~2500 BC) up to the last century with a gap around 10th to 6th century BC. All data have been relocated to Athens (37.97° N, 23.72° E) using the virtual geomagnetic pole method. Data coming from direct measurements available in Greece for the last four centuries have been also added. The secular variation (SV) curves for declination and inclination have been obtained using hierarchical Bayesian modelling. For comparison, the dataset has been also analysed using the bi-variate moving average window technique with 150 years time window shifted by 75 years. The obtained smoothed curves accompanied by a 95 % confidence envelope are compared with archaeomagnetic data...
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1 Institute of Geology and Mineral Exploration, Mesogeion 70, 115 26, Athens, Greece; E,mail: [email protected] 2 Department of Mineralogy and Petrology, School of Geology, Aristotle University of Thessaloniki, PO Box 352,1, 54124... more
1 Institute of Geology and Mineral Exploration, Mesogeion 70, 115 26, Athens, Greece; E,mail: [email protected] 2 Department of Mineralogy and Petrology, School of Geology, Aristotle University of Thessaloniki, PO Box 352,1, 54124 Thessaloniki, Greece; E,mail: sarantis@ ...
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AbstractThis study aims at unravel the geotectonic evolution of northern Greece prior to the already established Tertiary clockwise rotation. Therefore, Mesozoie sediments, Early Mesozoie ophiolites and Carboniferous granites were... more
AbstractThis study aims at unravel the geotectonic evolution of northern Greece prior to the already established Tertiary clockwise rotation. Therefore, Mesozoie sediments, Early Mesozoie ophiolites and Carboniferous granites were sampled. While the metamorphosed and/or too weakly magnetized limestones had to be rejected, the gabbros and serpentinites of the 80 km long Chalkidiki belt (40.4°N, 23.3”E), and the granites of the northern Pelagonian zone (40.8°N, 21.2°E) have yielded similar results interpretable in terms of geoleetonies. In both areas the demagnetizing process has revealed a poh phased magnetic evolution.The oldest magnetizations, labelled M (D=311°, I=20°, a95, = 15°; VGP: 37°N, 272.5°, for the ophiolites; D=320.5°, I = 26°, a95 =11°; VGP : 46°N, 264.5”E, for the granites) are interpreted as overprints acquired in Late Jurassic-Cretaceous times. The younger magnetizations, called C2 (D = 66°, I = 28°, a95 = 9°; VGP : 28°N, 117°E, in the ophiolites ; D=64°, I = 2° a95, = 11°; VCP : 20°N, I28...
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The present article comprises a multidisciplinary archaeometric approach for the study of Hellenistic and Early Roman kilns in Greece. A collection of previously published and new archaeomagnetic data are combined with new results from... more
The present article comprises a multidisciplinary archaeometric approach for the study of Hellenistic and Early Roman kilns in Greece. A collection of previously published and new archaeomagnetic data are combined with new results from mineralogical analytical experiments. The sampled material came from four areas, covering different geological contexts: Katerini, Olympiada, and Polymylos in mainland Greece, and the island of Paros. Extensive rock-magnetic experiments, including identification of the dominant ferromagnetic minerals present, their domain state, and mineralogical alterations during laboratory treatments, have been carried out in order to examine the magnetic properties of the studied materials and prove their suitability for reliable archaeomagnetic determinations. Magnetic cleaning provided well-defined archaeomagnetic directions, and archaeointensity measurements were carried out using both the Thellier-Thellier and Triaxe protocols. Information from both magnetic a...
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Tertiary plutonic bodies crop out over large areas in the Rhodope Massif, Northern Greece. A detailed magnetic study has been undertaken on the composite Vrondou granitoid. This large, almost 300 km2, pluton is composed of two different... more
Tertiary plutonic bodies crop out over large areas in the Rhodope Massif, Northern Greece. A detailed magnetic study has been undertaken on the composite Vrondou granitoid. This large, almost 300 km2, pluton is composed of two different intrusions: the locally strongly mylonitized Early Miocene West Vrondou, and the isotropic-looking Early Oligocene East Vrondou body. However, the boundary between these two parts is still unknown; this is one of the issues our study will attempt to clarify. Both AMS (anisotropy of magnetic susceptibility) and paleomagnetic measurements were performed on samples from 40 sites spread around the pluton. High bulk magnetic susceptibility indicates that the main carriers of susceptibility are ferromagnetic minerals; further analysis verified the contribution of magnetite and haematite. The anisotropy degree ranges from 18 to 60% and the shape parameter, T, manifests mostly oblate ellipsoids. Both demagnetization techniques were used in samples from all t...
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Page 1. Palaeomagnetism as a tool for testing geodynamic models in the North Aegean: convergences, controversies and a further hypothesis ... This distribution is seen in the area between south Albania and the western Greek Rhodope. ...
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Abstract In the present study we report on archaeomagnetic and luminescence results from three ceramic kilns unearthed in a workshop during the subway (METRO) excavations in Thessaloniki (N. Greece) as well as from a small kiln at... more
Abstract In the present study we report on archaeomagnetic and luminescence results from three ceramic kilns unearthed in a workshop during the subway (METRO) excavations in Thessaloniki (N. Greece) as well as from a small kiln at Ierissos (Chalkidiki). The first settlement is situated in the western part of the city where several similar workshops were excavated in the past. The archaeological information attributed a possible Ottoman age to these structures and placed their last use after the 14th century CE. The other small kiln is one of the rare “in situ” remains within the settlement reported as “Medieval Ierissos”. A total of fifty-five hand samples were retrieved from the four kilns and studied following established archaeomagnetic protocols in order to define the full vector of the magnetization. Additionally thermoluminescence (TL) experiments have been performed on the same material for the Thessaloniki kilns and the obtained ages converge and refine the archaeological ones. At Ierissos optically stimulated luminescence (OSL) experiments on five samples revealed the firing history of the structure. The combination of archaeological and/or TL-OSL information allowed to define four new full vector recordings for the improvement of the secular variation curves during the second millennium CE where intense variations of the Geomagnetic Field are reported from several places in Europe. The new data, together with recently published ones for the first millennium CE, allow to update the directional reference curves, poorly constrained for this period.
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ABSTRACT Archaeomagnetism has been continuously developed over the last three decades. Backed archaeological features such as pottery, kilns or burnt structures, provide reliable data as they usually carry a strong and stable... more
ABSTRACT Archaeomagnetism has been continuously developed over the last three decades. Backed archaeological features such as pottery, kilns or burnt structures, provide reliable data as they usually carry a strong and stable thermo-remanent magnetization acquired during the last firing. Numerous studies have provided high quality data for both the direction and intensity of the geomagnetic field essentially in Europe (e. g. compilations Genevey et al 2008, G3, Kovacheva et al, 2009, G3). In particular, Greece provides a lot of archaeological materials and numerous data are available (e. g. Aitken et al 1984, PEPI, Aitken et al 1989, PEPI, De Marco et al, 2008, Phys. Chem. Earth) from archaeomagnetic features or historical lava flows (Spassov et al, 2010, G3). The Greek secular variation curves (SVCs) are available for the last 8 millennia for the intensity and the last 6 millenia for the direction. Nevertheless, the coverage of the archaeological periods remains with several gaps for periods older than 2500 BC (Genevey et al, 2008, G3 and Kovacheva et al, 2009, G3). In this study, we present paleointensity results from Neolithic settlements in Northern Greece. Samples have been collected from four different archaeological sites: burnt structures and ceramics in Avgi (Kastoria, 5400-5100 B.C.) and Vasili (Farsala, 6000 B.C.), one kiln with the associated ceramics from Sossandra (Aridaia, 5000-4600 B.C.) and one ceramic collection from Dikili Tash (Kavala, 4800 B.C.). The samples have been subjected to a standard magnetic analysis in order to define the stability of the magnetic carriers and fulfil all the required criteria for the estimation of the palaeointensity. We obtained two reliable palaeointensities for the Avgi and Vasili sites of 38 and 48 μT respectively and a high mean paleointensity value arround 85 μT for the Dikili Tash site. These results are compared with the SVCs from neighbouring countries as well as with recent compilations and global models. We concluded that most of the old determinations are strongly scattered due to the absence of the correction of anisotropy of thermo-remanence in most of the studies.
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Ο αρχαιομαγνητισμός αποτελεί έναν κλάδο που συνδυάζει τη γεωφυσική με την αρχαιολογία και έχει διάφορες εφαρμογές, με πιο γνωστή τη χρονολόγηση θέσεων μέσω της μελέτης του γεωμαγνητικού πεδίου του παρελθόντος, όπως καταγράφεται στους... more
Ο αρχαιομαγνητισμός αποτελεί έναν κλάδο που συνδυάζει τη γεωφυσική με την αρχαιολογία και έχει διάφορες εφαρμογές, με πιο γνωστή τη χρονολόγηση θέσεων μέσω της μελέτης του γεωμαγνητικού πεδίου του παρελθόντος, όπως καταγράφεται στους ψημένους πηλούς που περιέχουν οξείδια του σιδήρου. Αφού θερμανθούν σε υψηλές θερμοκρασίες και στη συνέχεια ψυχθούν, αυτά τα οξείδια καταγράφουν την διεύθυνση και την ένταση του μαγνητικού πεδίου της γης στον τόπο και χρόνο της διαδικασίας. Αυτή η πληροφορία μπορεί να ανακτηθεί και έχει διπλή εφαρμογή: (1) εάν η χρονολόγηση του υλικού που μελετήθηκε βασίζεται σε ανεξάρτητες μεθόδους, τα αποτελέσματα μπορούν να χρησιμοποιηθούν ως σημεία αναφοράς για τη δημιουργία ή Καμπύλων Αιώνιας Μεταβολής (Secular Variation Curves (SVCs)) για την περιοχή, (2) εάν το υλικό είναι αβέβαιης χρονολόγησης, τότε αυτές οι καμπύλες, όταν είναι διαθέσιμες, μπορούν να χρησιμοποιηθούν για τη χρονολόγησή του, με μικρό κόστος και βαθμό φθοράς. Η συστηματική έρευνα στην Ελλάδα κατά τ...
Fired structures are abundant in Northern Greece and can be used for accurate estimations of the Earth's ancient magnetic field components. Two kilns belonging to the Classic-Hellenistic period have been sampled in Amphipolis and... more
Fired structures are abundant in Northern Greece and can be used for accurate estimations of the Earth's ancient magnetic field components. Two kilns belonging to the Classic-Hellenistic period have been sampled in Amphipolis and archaeointensity measurements have been performed on a set of 12 samples. Together with detailed rock magnetic studies, three reliable archaeointensity values (one from each kiln and one from a brick) have been obtained, in good correlation with the Bulgarian reference archaeomagnetic curve.
New palaeomagnetic and rock magnetic data obtained from the plio-quaternary volcanics in Almopias (NW Greece) are presented, together with existing ones from two other localities (Thessaly and Milos) in the Aegean extensional area. In... more
New palaeomagnetic and rock magnetic data obtained from the plio-quaternary volcanics in Almopias (NW Greece) are presented, together with existing ones from two other localities (Thessaly and Milos) in the Aegean extensional area. In most cases a stable component, slightly deviated from the expected direction, has been identified. Rock magnetic analysis reveals the presence of either magnetite (Thessaly), hematite (Milos) or both (Almopias) The anisotropy of magnetic susceptibility reaches significant levels for only part of the samples whereas the anisotropy ellipsoid could be defined in only one case (Almopias). The existing structural data for the three areas, together with fault plane solutions provide a representative deformation pattern. Comparison of -small- rotation angles and possible rotation of the stress field has been possible in the case of Almopias.
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The emplacement and tectonic evolution of the Tertiary Vrondou granitoid in the Greek Rhodope has been studied by a combination of field tectonic, microtextural and anisotropy of magnetic susceptibility (AMS) methods. The Vrondou pluton... more
The emplacement and tectonic evolution of the Tertiary Vrondou granitoid in the Greek Rhodope has been studied by a combination of field tectonic, microtextural and anisotropy of magnetic susceptibility (AMS) methods. The Vrondou pluton is composed of at least two intrusions, a Mid-Oligocene one at its eastern and an Early Miocene at its western parts. Room for the emplacement in both cases was provided by the opening of an extensional ramp space within a several km thick, mid-crustal subhorizontal shear zone, with a top to the SW sense, active during the Mid-Oligocene to Early Miocene period. The older eastern part of the pluton is much less deformed than the younger western part. Magmatic textures are well preserved in the older intrusion whereas they are scarcely present in the younger one. They indicate a NW-SE direction of magmatic flow in both cases. Sub-solidus plastic deformation affected mostly the younger western part of the pluton and only locally the older eastern one. I...
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The Minoan eruption of Santorini volcano (Greece) took place in the Late Bronze Age (17th century BC) and produced a great volume of volcanic products that covered the whole island and buried every human settlement under meters of... more
The Minoan eruption of Santorini volcano (Greece) took place in the Late Bronze Age (17th century BC) and produced a great volume of volcanic products that covered the whole island and buried every human settlement under meters of pyroclastic deposits. In this study we used thermal analysis of the magnetic remanence carried by pottery fragments buried under the pyroclastic deposits in order to estimate the thermal effect of the Minoan volcanic products on the pre-eruption habitation level. A total of 70 samples, prepared from 45 independent pottery fragments, have been studied. Samples were collected from three different sites, situated at the southern part of the island. Stepwise thermal demagnetizations reveal that the pottery fragments generally carry a two-component remanent magnetization. Interpretation of the demagnetization results using the normalised intensity decay curves and the orthogonal projection diagrams indicates that most samples were re-heated at temperatures ar...
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Archaeomagnetism combines the magnetic properties of baked materials with Archaeology. The archaeomagnetic method can be applied to any kind of permanent - in situ or displaced- burnt structures, such as kilns, ovens, hearths, burnt... more
Archaeomagnetism combines the magnetic properties of baked materials with Archaeology. The archaeomagnetic method can be applied to any kind of permanent - in situ or displaced- burnt structures, such as kilns, ovens, hearths, burnt floors, tiles, bricks and pottery fragments, the latter for intensity measurements only. In this study we present the latest archaeomagnetic results from archaeological sites which are distributed in N. Greece (Polymylos, Sani, Thesssaloniki). The Natural Remanent Magnetization (NRM) and the magnetic susceptibility of the samples have been initially measured. The samples have been subjected to magnetic cleaning (AF and Thermal demagnetizations) and this procedure revealed the characteristic component of the ancient magnetic field. Rock magnetic experiments such as acquisition of the Isothermal Remanent Magnetization (IRM) and thermomagnetic analysis have been performed in pilot samples in order to identify the main magnetic carriers. Finally the secular ...
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Gravity and magnetic data were used in the study of Philippi basin and intrusion. The most rigorous methods were used for the recompilation of the aeromagnetic map of Macedonia and Thrace. Philippi basin has a maximum depth of about 5.4... more
Gravity and magnetic data were used in the study of Philippi basin and intrusion. The most rigorous methods were used for the recompilation of the aeromagnetic map of Macedonia and Thrace. Philippi basin has a maximum depth of about 5.4 km. The aeromagnetic data reveal the presence of a large intrusion, much greater than the two small granitic outcrops.
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Thermal remanent magnetization analyses were carried out on Late Bronze Age pottery fragments in order to estimate the deposition equilibrium temperature of the fall pyroclastic deposits of the Minoan eruption (Santorini, Greece) and... more
Thermal remanent magnetization analyses were carried out on Late Bronze Age pottery fragments in order to estimate the deposition equilibrium temperature of the fall pyroclastic deposits of the Minoan eruption (Santorini, Greece) and their thermal effect on the pre- Minoan habitation level. The collected pottery samples were laying on the pre-Minoan palaeosoil surface and were completely covered and buried by the first pyroclastic pumice fall products of the eruption. Samples come from various sites, mainly situated at the southern part of the island. Stepwise thermal demagnetizations reveal that the pottery fragments carried a two-component remanent magnetization. Interpretation of the demagnetization results using the normalised intensity decay curves and the orthogonal projection diagrams indicates that most samples were re-heated at temperatures around 160-260 oC. The estimated temperatures represent the equilibrium temperatures obtained after the deposition of the pumice fall a...
The present work focuses on the study of the main ophiolite complex ofNorthern Greece, which is one of the dominant geological features in thebroader Aegean area, by the use of geophysical (gravity and magnetic)data. This ophiolite... more
The present work focuses on the study of the main ophiolite complex ofNorthern Greece, which is one of the dominant geological features in thebroader Aegean area, by the use of geophysical (gravity and magnetic)data. This ophiolite complex, which trends in a NW-SE direction, startsat the eastern part of the borders of Greece with F.Y.R.O.M. and continuesup to the southern part
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ABSTRACT The large Protobyzantine settlement of Megali Kypsa was excavated at the NW part of Chalkidiki peninsula (North Greece). Among the numerous residential buildings a big ceramic complex with twelve kilns was unearthed. Nine of the... more
ABSTRACT The large Protobyzantine settlement of Megali Kypsa was excavated at the NW part of Chalkidiki peninsula (North Greece). Among the numerous residential buildings a big ceramic complex with twelve kilns was unearthed. Nine of the kilns were preserved fairly well and the archaeological investigation suggested a large ceramic production for local use and exportation. The three best preserved kilns were sampled for an archaeomagnetic study, while numerous TL dating results in combination with archaeological information constrained the last use of the kilns from the end of the 4th to the middle of the 5th century AD. Rock magnetic analyses have been performed on pilot samples and identified magnetite as the main carrier of the natural remanent magnetisation. The samples were subjected to both alternating field and thermal demagnetisation providing reliable directions. Intensities were calculated with the Triaxe protocol and yielded a mean value of 61.2 ± 1.8 μΤ. The obtained results are compared with regional and global geomagnetic field models (SCHA.DIF.3K and ARCH.3K). Our study provides 3 new full-vector data, improving the resolution of the Greek secular variation curve for this poorly documented period.
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We report on five new archeomagnetic field intensity data obtained in Greece from groups of pottery fragments precisely dated to between the middle of the fourth century and the beginning of the seventh century CE. These potsherds were... more
We report on five new archeomagnetic field intensity data obtained in Greece from groups of pottery fragments precisely dated to between the middle of the fourth century and the beginning of the seventh century CE. These potsherds were unearthed on the islands of Thasos (Northern Greece) and Delphi (Central Greece). Their dating is primarily ensured by typo-morphological arguments, combined with archeological and historical constraints. Archeointensity measurements were performed using the Triaxe protocol, which involves continuous magnetization measurements at high temperatures and which allows us to overcome the thermoremanent magnetization anisotropy and cooling rate effects. Magnetic mineralogy measurements such as low-field magnetic susceptibility versus temperature and thermal demagnetization of three orthogonal IRM components have iden- tified magnetite with possible impurities as the main carrier of the magnetization. The new data range from 52.0μT to 61.5μT after reduction to Thessaloniki and show an increase in geomagnetic field intensity in Greece during the Early Byzantine period. They appear in good agreement with previous intensity results satisfying a set of quality criteria and obtained in a region of 700 km around Thessaloniki, therefore incorporating data from Bulgaria, Greece and South Italy. This study is part of an ongoing effort to better constrain the evolution in geomagnetic field intensity in the Balkans over the past few millennia, with potential use for dating in arche- ology. The rapid intensity variations documented here during the Early Byzantine period are clearly of interest in this respect.