METhods of NATurAl sciENcEs for ThE rEcoNsTrucTioN of ThE

* VetroVa M.N. — st. Petersburg state university, st. Petersburg, orciD 0000-0002-8591-6178 KulKoVa M.a. — rsPu named after a.i. herzen, st. Petersburg; iiMc raN, st. Petersburg, orciD 0000-0001-9946-8751 Kashuba M. — institute of the history of Material culture of the russian academy of sciences, orciD 0000-0001-8901-8116 GaVrylyuK N.a. — institute of archaeology of the National academy of sciences of ukraine, Kyiv, orciD 0000-0002-2369-5701 GershKoVych ya.P. — institute of archaeology of the National academy of sciences of ukraine, orciD 0000-0002-5915-1300 Kaiser e. — Free university of berlin, berlin KulKoV a.M. — resource center «X-ray diffraction methods of research» st. Petersburg state university, st. Petersburg, orciD 0000-0002-2001-2231 https://doi.org/10.15407/archaeologyua2019.01.131


Introduction
the problem of the production of handmade pottery by nomads, first of all, the reconstruction of the ceramics firing mode is the task of studying the ceramics of mobile and sedentary communities of the Northern black sea region: early nomads and the population of the forest-steppe zone. 1 the work was carried out as a part of the project No. 90 216, supported by the Volkswagen Foundation (Germany).
in the steppe burials of the early nomads (10 th -8 th /7 th centuries bc) today found more than two hundred vessels of various purposes (for cooking, food storage, drinking and food), which are used in burials. Many vessels have direct analogies among the ceramics produced by the sedentary population that lived in the forest-steppe zone. Despite obvious similarities, there is no convincing evidence in the specialized literature whether a vessel could have been produced in a nomadic community or by sedentary population. the authors propose to consider this problem in a comprehensive manner, on the basis of modern analytical methods for the study of ancient ceramics. the purpose of this work is to show the possibilities of using the methods of natural sciences in solving the problem of the firing ceramics reconstruction by the nomadic and sedentary population. the first results of studying a few ceramic samples from the materials of the settlements (subotiv and Glinjeni ii-la shanz) and some vessels from the burials of the later Pre-scythian period are presented.
We show only the first results of using the Dta-tG method to determine the firing mode of ceramics. samples were also analyzed by X-ray phase analysis (XrF). the works were carried out by M.N. Vetrova, M.a. Kulkova a.M. Kulkov in the laboratory of the russian state Pedagogical university and X-ray Diffraction research Methods resource center of st. Petersburg state university. the method of diffraction thermogravimetric analysis is the most interesting and suitable for solving the problem.

DTA-TG method
Diffraction thermogravimetric analysis (Dta-tG) is widely used to determine the firing temperature of ceramics. the minerals are characterized by a stable solid phase and their composition can determine the firing temperature of vessels. During heating, reactions occur in minerals, and they are not observed upon reheating (Kulkova, yushkova 2008). Fig. 1. analyzed ceramic samples of the Northern black sea region early iron age: 1 -Glinjeni ii-la shanz; 2 -subotiv; 3 -Kasperovka, barrow 2, grave 5; 4 -Velykodolynske, group 1, barrow 2, grave 11; 5 -Pryshyb, barrow 41, grave 2 (references to sources are given in the text)

Samples and their research
an experimental research was conducted on fragments of vessels from the forest-steppe settlements of Glinjeni ii-la shanz (Glinjeni 10 2 ) and subotiv (subotiv 29), as well as the steppe burials of the early nomads Kasperovka (Kasperovka 89), Pryshyb (Pryshyb 105) and Velykodolynske (Velykodolynske 126). samples were analyzed by two methods.
The fortified settlement of Subotiv, the right bank of the Dnieper (Гершкович 2016): Sample Subotiv 29 ( fig. 1, 2) -the upper part of a non-ornamented bowl with a curved rim, about 20 cm in diameter. Found (belogrudovchernoles culture, the end of the 11 th -the end of the 9 th century bc). the functional group kitchen 1, according to ya. P. hershkovich (Гершкович 2016, рис. В66, 9; tab. K2).
the graves of the early nomads («cimmerian» culture, 9 th -8 th centuries bc -see: Gavrylyuk 2017: 242 ff., with all historiography): 2 the name and samples numbering are given according to the project database.
Sample Velykodolynske 126 (Velykodolynske, group 1, barrow 2, grave 11 -Суботи�, Чер�яков, Ядвичук 1976, 192-193) (fig. 1, 4) -a polished beaker with a high arcuate neck, an outward-bent rim, a spherical body and a rounded bottom with a hole. the upper part of the vessel body is decorated with a belt of carved geometric pattern, boun-   Table 2. The results of diffraction thermogravimetric analysis of ceramics ded above by a low roller and 4 symmetrically located single (2) and double conical protrusions-stops. on the roller there are oblique notches. type 4, option 1, according to N.a. Gavrylyuk. Dimensions: height 13 cm, diameter of the rim 10 cm, maximum diameter of the body 14 cm, diameter of the bottom 3.0 cm, ratio of height and maximum diameter of the body 0.92 (Гаврил�к 2017, 70, 154, рис. 17). samples of ceramics were carefully wiped in an agate mortar for X-ray and thermogravimetric analysis. X-ray phase analysis (XrF) was performed on an automatic powder diffractometer rigaku «ultima iV» with radiation co Kα. shooting speed 2°/ min. angles 2 Ө5-70°. Filming was carried out at the st. Petersburg state university resource center «X-ray diffraction research methods (rMi)». Dta was held in two resource centers of st. Petersburg state university. the rc «rMi» on the device Netzsch sta 449 F3 and rc «innovative technologies of composite nanomaterials» on the device setsys evolution 16 (setaram, France). During tGa samples were heated from room temperature to 1100°С in oxygen (20 % N 2 80 % o 2 ) atmosphere with speed 10°/min.

Results and discussion
XrF showed a similar mineralogical and phase composition of ceramic samples (tab. 1). Quartz, mica (muscovite/phlogopite), and feldspar (microcline/albite) were found in all ceramic samples. calcite, rutile, anatase, amphibole and magnetite were also diagnosed by XrD.
Dta curves ( fig. 2) show endothermic and exothermic peaks, which differ due to differences in mineral composition. Wide endothermic peak in the range 30-200 °С in all samples shows the output of adsorption water, that is, the dehydration of unbound water. this effect is also confirmed by a change in the mass of the samples in this temperature range.
broad exothermic peak in the range 250-500 °С indicates burnout of organic material present in all samples. apparently, the organic material was added as a binder or contained in the clays of which the vessels were made. endothermic peaks, ranging from 550 to 700 °С, are responsible for the release of water of crystallization from layered silicates. Peak in the area 650 °С indicates the preservation of kaolinite in the process of firing ceramics in antiquity and, accordingly, the firing temperature of such ceramics did not exceed this temperature value (ravisankar et al. 2014). illite/muscovite begins to lose water at a temperature of about 700 °С and their complete dehydration occurs at a temperature 850-900 °С (Maritan et al. 2005). on the Dta curves of the samples with the highest content (according to X-ray diffraction data) of illite/muscovite, we observe endothermic peaks in this area 679 °С (Glinjeni 10), 670 °С (Pryshyb 105) and 650 °С (Velykodolynske 126). and the greatest loss of mass in temperatures responsible for the dehydration of clay minerals 200-400 °c is shown by the same samples (tab. 2).
carbonates begin to decompose when the temperature is 650 °С. For systems with a high content of calcite and / or with a large number of coarse fragments of carbonate rocks, this process can continue until 1000-1100 °С (trindade et al. 2009). in the sample Glinjeni 10 with the highest mineral content of the carbonate group, a bright endothermic peak is observed at a temperature of 854 °c. also in this sample, the most pronounced mass loss is 1.76 % at a temperature of 600-850 °c, which indicates the decomposition of carbonate materials (bayazit et al. 2016). in other samples, the peak in this area is weak and, according to X-ray diffraction data, calcite is present in an amount of less than 1.0 % or is completely absent.
the endothermic peak observed in the temperature range 566-576 °c is responsible for the alpha (α) -beta (β) quartz phase transition. this peak is manifested in all investigated samples. the long stay of ceramics in the burials (and in the cultural layer of the settlements) could lead to the appearance of secondary clay and carbonate minerals. Peaks around 650 °c, which are responsible for the dehydration of clay minerals, can relate to the decomposition of newly formed layered silicates and cannot be used to determine the calcination regime. Quartz neoplasm does not occur during ceramics burial.