Archaeomagnetic investigations in Bolgar (Tatarstan)
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Authors
Kosareva, Lina R.
Kuzina, Dilyara M.
Nurgaliev, Danis K.
Sitdikov, Airat G.
Luneva, Olga V.
Khasanov, Damir I.
Suttie, Neil
Spassov, Simo
Discipline
Earth and related Environmental sciences
History and Archaeology
Subject
Archaeology, Golden Horde, Archaeomagnetism, Thellier-Thellier method, Bayesian statistics, Geomagnetic field, Palaeosecular variation, Magnetic property analyses
Audience
Scientific
Date
2020-04-27Publisher
Springer
Metadata
Show full item recordDescription
The objective of this study is to provide a well-dated point for a future palaeosecular
variation (PSV) reference curve for western Russia. For this purpose archaeomagnetic
and magnetic property analyses were carried out on a pottery kiln unearthed at the
UNESCO World Heritage site of ancient Bolgar, having a rather precise age dating. The
archaeological context provided an age between 1340 and 1360 C.E. The characteristic
remanence vector was determined through alternating field demagnetisation and Thellier-
Thellier palaeointensity experiments. Some innovations were introduced regarding
palaeointensity. The check testing the equality of blocking and unblocking temperature
was redefined. This allowed waiving the commonly used additional zero-field cooling
steps during the Thellier-Thellier experiment. Another innovation concerns the
calculation of archaeointensity at structure level. A Bayesian approach was introduced
for averaging individual specimen archaeointensities using a prior probability
distribution of unknown uncertainties. Next, an additional prior probability distribution
was used to correct for cooling rate effects. This resulted in a lower uncertainty compared
to common practice and in eluding time consuming cooling rate experiments. The
complex magnetic mineralogy consists of maghaemite, multi-domain haematite and
Al-substituted haematite. Some samples contained also some non-stoichiometric
magnetite. The magnetic mineralogy was determined through hysteresis loops, backfield
and remanence decay curves, measurements of the frequency dependence of magnetic
susceptibility and through low temperature magnetisation curves. Accompanying hightemperature
thermomagnetic analyses revealed an excellent thermo-chemical stability of
the studied specimens. Directions obtained from alternating field demagnetisation and
those extracted from archaeointensity experiments are congruent and have low
uncertainties. The obtained archaeomagnetic results are fairly in agreement with global
geomagnetic field models and contemporary PSV data of the wider area. The geomagnetic field vector obtained for ancient Bolgar is of high quality, deserving thus its
inclusion in a future PSV reference curve for European Russia.
Citation
Kosareva, L.R., Kuzina, D.M., Nurgaliev, D.K. et al. Archaeomagnetic investigations in Bolgar (Tatarstan). Stud Geophys Geod (2020). https://doi.org/10.1007/s11200-019-0493-3
Identifiers
Type
Article
Peer-Review
Yes
Language
eng