Provenance of Prehistoric Obsidian Artifacts of Khoy Plain in NW Iran Using X-ray Fluorescence (XRF) Analysis

There are many uses of obsidian by prehistoric peoples that includes a long period from Paleolithic until the Bronze Age and before the invention of metal. Due to its chemical structure, obsidian has special potential for fingerprinting and provenance studies, and it allows for the reconstruction of long-distance trade and the history of prehistoric exchanges in various parts of the Western Asia. Until now, only obsidian mines have been identified in Anatolia (northeast, southeast, central, western) and the Caucasus, and based on experimental analysis of the obsidian tools of the ancient sites of the northwest of Iran, however, some samples obtained from various parts of Iran, have remained unexploited due to lack of studies on the origins and identification of major mines and other indigenous mines. This research is trying to analyze 38 samples of obsidian artifacts belong to Chalcolithic and Bronze Age (Kura-Araxes) cultures, from 9 different prehistoric sites in Khoy region with using the XRF analysis method for identification of Chalcolithic and Bronze Age provenance sources, and to clarify that in which period which sources have been used predominantly and whether changes to the source have been made by changing in each period or not they used only the same sources in different periods. Our analysis show that 53 artifacts from the prehistoric sites of Khoy came from nine different sources. The sources are: Meydan Dag (15 artifacts), Syunik (8 artifacts), Tsakhunyats (4 artifacts), Suphan Dag (3 artifacts), Gutansar (3 artifacts), Arteni (2 artifacts) and Nemrut Dag and Tendurek (1 artifact) and unassigned (1 artifact). According to analysis results Meydan Dag and Syunik could be suggested as two main obsidian sources of prehistoric sites of Khoy region.
Keywords: Obsidian, Kul Tape, Hadishahr, Obsidian Mines, XRF Portable.
 
Introduction & Method
Obsidian is a material widely used by prehistoric groups and found in abundance on archaeological sites in the Taurus-Zagros region. Provenance studies have been the focus of intense research and debate among archaeologists and geologists over the past 60 years, especially those focusing on the Anatolian plateau and the Caucasus. However, obsidian studies in Iran have remained in an early stage, and only recent research on obsidian outcrops, carried out in parallel with prehistoric obsidian provenance studies, has provided the first opportunity to develop a database (Abedi et al., In press; Khademi Nadooshan et al., 2013; Abedi, 2015) and to outline a horizon and a perspective for obsidian studies in this country. In the mid-1960s, Renfrew and his colleagues (Renfrew et al., 1966; 1968; Renfrew and Dixon, 1976) used geochemical methods to study obsidian collections from the Zagros Mountains, the Urmia basin and the Central Plateau. Later, Blackman (1984) and other researchers demonstrated that long-distance trade existed between ancient sites in Iran and the obsidian sources located in Anatolia and the Caucasus during prehistoric periods (Bigazzi et al., 1998; Chataigner et al., 1998; Poidevin, 1998; Frahm, 2010).
Recently, additional sourcing and provenance studies have been carried out by Iranian scholars (Agha-Aligol et al., 2015; Khademi et al., 2007, 2010; Ghorabi et al., 2008; Niknami et al., 2010; ; Khademi Nadooshan et al., 2013; Abedi, 2015). Some of these articles (Ghorabi et al., 2010; Niknami et al., 2010) suggest that obsidian tools may have come from an unknown source located in Iran (perhaps Sahand and Sabalan Mountain). Some of the results provided by these studies were inconclusive: characterizations presenting sometimes clear parallels with Armenian sources, or providing values (on SiO2, for instance) never found in obsidian (Agha-Aligol et al., 2015; Ghorabi et al., 2010; Khademi et al., 2007). In order to add new data to this discussion, this paper presents the results of the analysis of 38 obsidian artifacts from the Late Neolithic/Transitional Chalcolithic and Chalcolithic to Early Bronze Age periods in Khoy plain of NW Iran. This is the first time archaeometrical analysis will done on prehistoric obsidian artifacts of the region. After collecting obsidian assemblages from all prehistoric sites of Khoy, fundamental questions have been raised: what is the main obsidian source of the region? It is mono source or multiple source? Can we consider Syunik and Meydan Dag as main obsidian sources of Khoy region during prehistory? According to analysis possible answer to this questions will make it possible to draw local and long-distance trade between Khoy and Lake Urmia in one hand and southern Caucasus and Eastern Anatolia on the other hand.
The present research is qualitative-quantitative based on methodology, after field archaeological sampling (38 artifacts from 9 different prehistoric sites), X-ray Fluorescence Analysis (XRF) method has been used to determine quantitatively the amount of main and rare elements.
 
The Obsidian Analysis Results of Khoy Archaeological Sites
The characterizations were determined using a XRF Philips PW1410 model. Some of the most reliable element concentrations in obsidian that can be obtained using XRF are Rb, Sr, Y, Zr and Nb, if the concentrations are above the detection limit (Darabi and Glascock, 2013; Maziar and Glascock, 2017). The compositional data measured for the 38 artefacts by XRF are listed in Table 2-3. A scatter plot of the Zr versus Rb concentration (Fig. 4-5) allows recognition of nine clusters from nine different archaeological site (Ghardash Khan, Shorshorik, Pirkandi, Dava Goz, Ali Sheikh (Kooshish), Maran, Doozdaghi (Amirbeigh), Kul Tepe Ghoharan and Chirkandi) which match the composition of the well-known sources: Meydan Dag (15 artifacts), Syunik (8 artifacts), Tsakhunyats (4 artifacts), Suphan Dag (3 artifacts), Gutansar (3 artifacts), Arteni (2 artifacts) and Nemrut Dag and Tendurek (1 artifact) and unassigned (1 artifact).  (Table. 3-4). During the Late Neolithic to the end of Early Bronze Age periods a polysource model operated, as at least six sources (Meydan, Syunik, Tsakhunyats, Suphan, Gutansar and Arteni) are heavily represented across a large assemblage (N= 33), whereas the whole data results indicates a bi-source model heavily dominated by the Meydan Dag and Syunik obsidians.
According to the interpretation of two seasons of excavations and obsidian studies, the inhabitants of Kul Tepe and Dava Goz and Khoy plain in general, at least in the Chalcolithic and Bronze Age, were agro-pastoralists who spent most of their times at the plain sites like Kul Tepe and Dava Goz or mentioned prehistoric sites engaged in farming and other household activities and moved seasonally in summer in search of pastures with their herds to the highlands. New research at the Chalcolithic site of Godedzor indicates a seasonal summer campsite in the highlands near the Syunik (Sevkar) obsidian source. This site showed good evidence of material known from sites in the Lake Urmia Basin, especially ceramic types. It presents Chalcolithic signs of Dalma and Pisdeli cultures. Excavators at Godedzor (Chataigner et al., 2010) suggest that this site was a summer seasonal campsite for inhabitants from Kul Tepe, Dava Goz and Khoy prehistoric sites and the Lake Urmia Basin (wintering region), using the obsidian from Syunik. They also suggest that obsidian was used only for local trade and personal use, not for extensive trade, because it did not diffuse beyond the Lake Urmia Basin. Obsidian appears to have been a byproduct of the pastoral lifestyle for local trade between the Lake Urmia basin and the Caucasus region. Analysis of Kul Tepe artifacts suggests that sites like Kul Tepe and Dava Göz and Khoy prehistoric sites (Abedi, 2017; Abedit et al., 2018 a-b) had an intermediate role in transferring obsidian raw materials to NW Iran and the Lake Urmia Basin during Chalcolithic and Early Bronze Age periods.
 
Conclusion
The chemical analysis of 38 obsidian artifacts from the Khoy archaeological sites (Ghardash Khan, Shorshorik, Pirkandi, Dava Goz, Ali Sheikh (Kooshish), Maran, Doozdaghi (Amirbeigh), Kul Tepe Ghoharan and Chirkandi) proved that the main source of obsidian was Meydan Dag (15 samples) and Syunik (8 samples) but obsidian from other sources Tsakhunyats (4 artifacts), Suphan Dag (3 artifacts), Gutansar (3 artifacts), Arteni (2 artifacts) and Nemrut Dag and Tendurek (1 artifact) and unassigned (1 artifact) were also utilized. Only one specimen had an unassigned source. In addition, according to the study of obsidian artifacts, analysed by XRF, it can be suggested, that from 38 samples, 15 specimens belong to the Meydan Dağ source and 8 samples come from Syunik. The results suggested that the main source used by Khoy prehistoric inhabitants during the Late Neolithic, Chalcolithic and the Early Bronze Age was Meydan Dağ and Syunik, although Tsakhunyats, Suphan Dag, Gutansar, Arteni and Nemrut Dağ and Tendurek have been used in a limited portion also. The intermediate role of Khoy and The importance of pastoral groups in transferring the raw material like obsidian from southern Caucasus and eastern Anatolia to the Lake Urmia Basin identified by the analyzing of the obsidian samples during this research.