Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Jordanova, Neli; Petrovský, Eduard; Kovacheva, Mary

doi:10.5636/jgg.49.543

Cited by 30 publications

(25 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…4b). Previous archaeo-and rock-magnetic studies (Jordanova et al 1997(Jordanova et al , 2003(Jordanova et al , 2004Spassov & Hus 2006;Herries et al 2007Herries et al , 2008Catanzariti et al 2008) have reported the existence of maghaemite in burnt archaeological remains.…”

Section: Magnetic Characterization Of Stabling Layers In Mirador Cavementioning

confidence: 99%

“…If in turn, maghaemite was formed by low temperature oxidation after TRM acquisition (secondary origin), the samples would be unsuitable for palaeointensity determination (Jordanova et al 1997), because the remanence would be a thermochemical remanent magnetization instead of a pure TRM. Even in that case archaeomagnetic (directional) data would still be reliable, when the remanence was acquired soon after the burning (which is likely).…”

Section: Magnetic Characterization Of Stabling Layers In Mirador Cavementioning

confidence: 99%

See 1 more Smart Citation

Rock-magnetic analyses as a tool to investigate archaeological fired sediments: a case study of Mirador cave (Sierra de Atapuerca, Spain)

Carrancho

Villalaín

Angelucci

et al. 2009

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YHere we report a detailed mineral magnetic study of Neolithic burnt levels in the Mirador Cave (Sierra de Atapuerca, Burgos, Spain) to reconstruct the burning history and to investigate their suitability for archaeomagnetic purposes. As a consequence of the ancient burning, a characteristic facies sequence was developed along the Holocene stratigraphy. From top to bottom it includes: (i) 2-10 cm ash layers, (ii) ∼2 cm underlying rubefied layers and (iii) clay, mainly unburnt and of variable thickness. In some cases a thermally altered facies (2-6 cm) with a heterogeneous texture was identified (facies TF), usually between rubefactions and the unburnt levels. 126 oriented samples from 4 units (MIR12, 15, 18 and 21) and a 2 m section, all comprised between units MIR21 (6380 ± 40 14 C BP) and MIR9 (5090 ± 40 14 C BP) were analysed with rock magnetic methods. In addition, bulk sediment from each facies that comprise the Neolithic sequence was investigated. Measurements included: stepwise alternating field and thermal demagnetization of natural remanent magnetization (NRM), viscosity experiments, determination of the anisotropy of the magnetic susceptibility (AMS), the susceptibility frequency dependence at room temperature and determination of the temperature dependence of the susceptibility. Additional experiments consisted in the determination of the behaviour of anhysteretic and isothermal (IRM) remanences, magnetic hysteresis loops, first-order-reversal-curve diagrams, and thermal demagnetization of threeaxial IRM. It appeared that the facies all show a fairly similar magnetic mineralogy and grain size dominated by low-titanium magnetite that is often partially maghaemitized. Main differences constitute the amount of superparamagnetic particles that is higher in unburnt strata concurring with a less well-defined NRM behaviour. The magnetic mineral concentration is notably higher in ashes. This homogeneity strongly suggests that similar sources and burial conditions prevailed during Neolithic times. Agreeing with archaeological observations and favoured by rapid burial conditions, very limited alterations have been deduced. AMS data revealed the absence of fluid flow in the ash lenses sampled. Demagnetization revealed a stable single NRM component in ashes, a single or two-component NRM in rubefactions and less stable multicomponent behaviour in clays. In ashes, magnetic minerals are likely secondary in origin formed by low-temperature oxidization soon after burning. Although this thermochemical nature of the NRM invalidates the use of these sediments for palaeointensity studies, archaeomagnetic (directional) data can be successfully obtained because the burning and oxidation are closely confined in time.

show abstract

Section: Magnetic Characterization Of Stabling Layers In Mirador Cavementioning

confidence: 99%

Section: Magnetic Characterization Of Stabling Layers In Mirador Cavementioning

confidence: 99%

Rock-magnetic analyses as a tool to investigate archaeological fired sediments: a case study of Mirador cave (Sierra de Atapuerca, Spain)

Carrancho

Villalaín

Angelucci

et al. 2009

Geophysical Journal International

View full text Add to dashboard Cite

show abstract

“…The palaeointensity study was performed using the classical Thellier method (Thellier and Thellier, 1959) in two laboratories (the Geosciences Laboratory, University of Rennes 1, France and the Palaeomagnetic laboratory of the Geophysical Institute, Bulgarian Academy of Sciences, Sofia). In addition to other factors involved in the palaeointensity determination, such as the non-linearity of the Arai diagram, mineralogical changes, non-suitable magnetic characteristics, among others (Chauvin et al, 1991;Jordanova et al, 1997;Kovacheva et al, 1998;Jordanova et al, 2003), a detailed examination of the magnetic anisotropy effect on the palaeointensity results obtained from materials other than pottery is still required.…”

Section: Introductionmentioning

confidence: 99%

Remanence anisotropy effect on the palaeointensity results obtained from various archaeological materials, excluding pottery

et al. 2009

Self Cite

View full text Add to dashboard Cite

The effect of magnetic anisotropy on the palaeointensity results has been evaluated in different materials, including samples from archaeological structures of various ages, such as baked clay from prehistoric domestic ovens or pottery kilns, burnt soil from ancient fires, and bricks and bricks or tiles used in the kiln's construction. The remanence anisotropy was estimated by the thermoremanent (TRM) anisotropy tensor and isothermal remanence (IRM) tensor methods. The small anisotropy effect (less than 5%) observed in the palaeointensity results of baked clay from the relatively thin prehistoric oven's floors estimated previously through IRM anisotropy was confirmed by TRM anisotropy of this material. The new results demonstrate the possibility of using IRM anisotropy evaluation to correct baked clay palaeointensity data instead of the more difficult to determine TRM anisotropy ellipsoid. This is not always the case for the palaeointensity results from bricks and tiles. The anisotropy correction to palaeointensity results seems negligible for materials other than pottery. It would therefore appear that the palaeointensity determination is more sensitive to the degree of remanence anisotropy P and the angle between the natural remanent magnetization (NRM) vector and the laboratory field direction, than to the angle between the NRM and the maximum axis of the remanence anisotropy ellipsoid (K max ).

show abstract

“…In the literature, several pre-selection procedures before archaeointensity determinations have been proposed (e.g. Cui & Verosub 1995;Cui et al 1997;Jordanova et al 1997Jordanova et al , 2001Leonhardt et al 2004;Carvallo et al 2006). Nevertheless, some of these procedures are almost as time consuming as a Thellier experiment and a full success cannot still be guaranteed.…”

Section: Re-evaluation Of Previous Results Through Magnetic Measurementsmentioning

confidence: 99%

Investigating the archaeointensity determination success of prehistoric ceramics through a multidisciplinary approach: new and re-evaluated data from Greek collections

Kondopoulou¹,

Gómez‐Paccard

Aidona³

et al. 2017

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YThe Balkan area provides an almost continuous record of the geomagnetic field variations during the last eight millennia but important data dispersion and chronological gaps are still observed. In order to improve this pattern, we oriented our research towards the study of Greek prehistoric ceramics and pottery collections. We present here new archaeointensity and mineralogical results from pottery and ceramics collected in two Bronze Age sites in Northern Greece, corresponding to the middle third and middle second millennium BC. Thermal demagnetization experiments, thermomagnetic curves, thermal demagnetization measurements of three axes composite isothermal magnetization and first-order reversal curves (FORC) diagrams were performed in order to define the main magnetic carriers and select the most promising samples for archaeointensity determination. The results suggest that the majority of the studied materials are dominated by a mixture of superparamagnetic and stable single domain grains, with very little magnetic interactions. In almost all samples the main magnetic carrier observed is a low coercivity mineral, most probably magnetite and/or Ti-magnetite. Classical Thellier experiments, including both the thermoremanent magnetization anisotropy and cooling rate corrections were performed on the selected samples. Two new archaeointensities were obtained and compared with previous data available for Greece and neighbouring countries and with global geomagnetic field models results. In order to investigate the causes of the high rate of failure observed in our archaeointensity experiments, we re-examined the results obtained from the study of four collections already published by better characterizing the magnetic and mineralogical properties of the studied fragments. Specific hysteresis curves performed at different layers of ceramic fragments reveal an important degree of inhomogeneity. Mineralogical analysis of selected samples from the totality of six Greek prehistoric sites studied, including new X-ray powder diffraction analysis and a detailed description of the different geological contexts, is provided. The results suggest that the sherds were all fired in medium-high temperatures (mostly between 500• and 800• C). The nature of the baked clay paste in response to the local geology appears to account for a part of the variability in magnetic properties. We suggest that X-ray powder diffraction analyses and thorough examination of the geological environment in combination with a satisfactory knowledge of the corresponding excavations history might provide an additional tool to appropriately select pottery fragments before performing future archaeointensity experiments.

show abstract

Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Cited by 30 publications

References 50 publications

Rock-magnetic analyses as a tool to investigate archaeological fired sediments: a case study of Mirador cave (Sierra de Atapuerca, Spain)

Rock-magnetic analyses as a tool to investigate archaeological fired sediments: a case study of Mirador cave (Sierra de Atapuerca, Spain)

Remanence anisotropy effect on the palaeointensity results obtained from various archaeological materials, excluding pottery

Investigating the archaeointensity determination success of prehistoric ceramics through a multidisciplinary approach: new and re-evaluated data from Greek collections

Contact Info

Product

Resources

About