Radiocarbon dating, Bayesian analysis and archaeological evaluation
of the Late Avar cemetery at Pitvaros-Víztározó
Sikósi Zsuzsanna – Lőrinczy Gábor
Hadak útján. A népvándorláskor fiatal kutatóinak XXIV. konferenciája. Esztergom, 2014. november 4–6. Conference of young scholars on the Migration Period. November 4–6, 2014, Esztergom
MŐT Kiadványok 3.1 (2015) 707–736
DOI 10.55722/Arpad.Kiad.2015.3.1_27
A 225 síros késő avar temető 10 sírjából származó embertani anyagon 1999-ben Debrecenben, 2010-ben Poznanban végeztek radiokarbon vizsgálatokat. Mivel hat sír anyagát mindkét laboratóriumban vizsgálták, ezért ez a sorozat módszertani szempontból is jó lehetősé-get kínál a két laboratórium, a két mérési módszer egymással és a régészeti leletanyag alapján felállított kronológiával való összehasonlítására.
A vizsgálatba bevont férfisírok időrendi helyzetét a temető övgarnitúrás sírjai alapján felállít-ható összefüggő relatív kronológiai sorrend adja meg. A temető használatának kezdetét a 650–670 közötti időre, a temető felhagyását a 835/850 körüli időszakra tételezhetjük fel. A régészeti keltezéshez képest a sírok radiokarbon keltezése alapján a temető használatának egy jóval rövi-debb időszaka feltételezhető. Az abszolút dátumok szerint valószínűbb, hogy a temető használata már a 8. század végén befejeződött.
A tipokronológiai és a radiokarbon keltezés síronkénti, illetve a temető egészére vonatkozó össze-vetése után a mérésekből levonható néhány módszertani következtetésre hívnánk fel a figyelmet.
Kulcsszavak: 7–9. század, avar kor, tipokronológia, radiokarbon, abszolút és relatív kronológia
Ten samples taken from human skeletal remains of the Late Avar cemetery containing 225 graves were analyzed by conventional radiocarbon dating in the Laboratory of Environmental Studies, Institute for Nuclear Research of the Hungarian Academy of Sciences, Debrecen in 1999, and further eight AMS measurements on human skeletal remains were carried out in the Poznan Radiocarbon Laboratory in 2010. The latter measurements aimed to widen the range of radio-carbon analysed burials. Furthermore, samples were taken to both laboratories from six graves, therefore, this series of measurements provided an opportunity to compare the respective meth-ods of the two laboratories and compare typochronology with radiocarbon chronology.
Samples deriving from two female and ten male graves were radiocarbon measured. Two adultus female (Graves 116 and 203), one adultus male (Grave 12) and nine maturus male buri-als (Graves 51, 72, 125, 147, 167, 200, 205, 218) were analysed.
Typochronologically-based relative chronology of male burials containing belt sets was estab-lished. Archaeological dating of burials can be estimated within 30 to 50 years long periods. It is supposed that the use of the cemetery began between 650 and 670 and it was abandoned around 835/850. The cemetery might have been used during 170–180 years and served six “generations”.
The measurements were calibrated using the IntCal09 curve and the OxCal 4.2.2. software, hereafter we publish one-sigma data as a rule. Individual calibrated dates for the cemetery are between 596 (68.2%) 685 cal AD (Deb-8025, Grave 72) and 690 (68.2%) 809 cal AD (Deb-8016, Grave 147). Imprecision due to the wiggles and plateaux of the calibration curve can be decreased by Bayesian analysis, and five different models were built from the sequences of radi-ocarbon measurements. There is no difference between the models (model 1 and models 4–5) that take into consideration all the measurements. However, if the results of the two different lab-oratories are handled separately, we can see a slight difference due to the more precise measure-ments of the Poznan Radiocarbon Laboratory. According to radiocarbon dating, the span of use of the cemetery can be estimated much shorter than it is suggested by typochronology. Accord-ingly, the probability distribution representing the boundary date of the start of the cemetery’s use is 637 (68.2%) 666 cal AD which is in agreement with archaeological dating. Dating of the abandonment of the cemetery is much more difficult. Instead of the archaeologically estimated 9th century, the probability distribution for the boundary date of the end of the cemetery’s use is 695 (68.2%) 774 cal AD. We also carried out a grave-by-grave comparison of the results of typochronological and radiocarbon dating. The radiocarbon dating of the Late Avar period is strongly influenced by a sudden increase in 14C content between 774 and 775. It may be due to a short gamma-ray burst in the Galaxy that could inflict a fall in temperature, deplete the ozone layer and bring about an increase in the UVB radiation on Earth.
To sum up, radiocarbon data do not support the dating of the abandonment of the cemetery during the early or middle 9th century. According to the absolute dates it is more probable that the use of the cemetery had already finished by the end of the 8th century.
