Armenia, Georgia) and Eastern Turkey, Part 1: Source Characterization*

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Archaeometry 56, 1 (2014) 25–47 doi: 10.1111/arcm.12006

NEW DATA ON THE EXPLOITATION OF OBSIDIAN IN THE SOUTHERN CAUCASUS (ARMENIA, GEORGIA) AND EASTERN TURKEY, PART 1: SOURCE CHARACTERIZATION*

C. CHATAIGNER

Archéorient, UMR 5133, CNRS/Université Lyon 2, 7 rue Raulin, 69007 Lyon, France

and B. GRATUZE†

IRAMAT CEB, UMR 5060, CNRS/Université d’Orléans, 3 D rue de la Férollerie, 45071 Orléans Cedex 2, France

A large analytical programme involving both obsidian source characterization and obsidian artefact sourcing was initiated recently within the framework of the French archaeological mission ‘Caucasus’. The results will be presented in two parts: the ﬁrst part, this paper, deals with the presentation and characterization of obsidian outcrops in the southern Caucasus, while the second presents some results obtained from a selection of artefacts originating from different Armenian sites dated to between the Upper Palaeolithic and the Late Bronze Age. The same analytical method, LA–ICP–MS (laser ablation inductively coupled plasma mass spectrometry), has been used to characterize all the studied samples (both geological and archaeological). This method is more and more widely used to determine the elemental composition of obsidian artefacts, as it causes minimal damage to the studied objects. We present in this ﬁrst part new geochemical analyses on geological obsidians originating from the southern Cau- casus (Armenia, Georgia) and eastern Turkey. These data enhance our knowledge of the obsidian sources in these regions. A simple methodology, based on the use of three diagrams, is proposed to easily differentiate the deposits and to study the early exploitation of this material in the southern Caucasus.

KEYWORDS: OBSIDIAN GEOCHEMISTRY, LESSER CAUCASUS, ARMENIA, GEORGIA, EASTERN TURKEY, OBSIDIAN OUTCROPS, LA–ICP–MS ANALYSES

INTRODUCTION The southern Caucasus is a region in which obsidian represents practically the only material used by prehistoric populations for their tools and weapons. Indeed, obsidian deposits are plentiful in Armenia as well as beyond the periphery of its territory, in southern Georgia, western Azerbaijan and eastern Turkey (Fig. 1). Analysis of the chemical composition of these sources (Keller et al. 1996; Blackman et al. 1998; Poidevin 1998) and of artefacts coming from approximately 70 Transcaucasian archaeological sites dating from the sixth to the ﬁrst millennia bc (Badalyan et al. 2004) have enabled the establishment of an initial cartography of the movements of obsidian between the Neolithic and the Iron Age, and conﬁrmation of the great variability in their distribution in the region. The villagers obtained their supplies either from a single source or from several sources, and the nearest deposits were not necessarily the most favoured; the factor of direct linear distance,

Figure 1 The distribution of the obsidian sources in the southern Caucasus and eastern Turkey. often considered as a determinant in the choice of outcrops (Renfrew 1984), was thus not so important. The areas of diffusion of the obsidian sources also appear to have been highly contrasting. In certain cases (Chikiani), the material travelled in large quantities over great distances and in various directions. In other cases (Hatis), the area of diffusion is limited in quantity, distance and direction. Elsewhere (Geghasar), the obsidian was diffused in a limited quantity, but over very long distances or, on the contrary (Arteni), in high quantities over a limited territory.

SOURCES OF OBSIDIAN AND ANALYTICAL METHOD

The studied corpus Many sources of obsidian exist across the southern Caucasus. An exhaustive survey has enabled the collection of samples from all these sources, except for those in western Azerbaijan, and the study of the conditions of accessibility to the different primary (ﬂows, domes) and the secondary

(blocks transported by the rivers) deposits. Fifty-ﬁve geological samples, from different sources in Georgia and Armenia, as well as 25 samples from sources in eastern Turkey, have been analysed by LA–ICP–MS (IRAMAT, CNRS/Université d’Orléans) (Table 1).

LA–ICP–MS analysis Analyses of obsidian objects conducted at the Centre Ernest-Babelon of the IRAMAT (Orléans) are carried out using an Element XR mass spectrometer from Ther- mofisher Instrument and a VG UV microprobe ablation device. Routinely, concentrations of 38 elements are determined in obsidian objects. Among them, we find: • the main major and minor constituents (silicon, sodium, potassium, aluminium and iron), which enable classification of the obsidians according to their different types (calc-alkaline, peralkaline, hyperalkaline, hyperaluminous and metaluminous); • the main hydromagmaphile elements (Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Hf, Ta Th, U and rare earths), which characterize the magma and the volcanic rocks that derive from it (Cauvin et al. 1991; Gourgaud 1998). LA–ICP–MS analysis of obsidian objects operates as follows. The objects are placed in the ablation cell together with the reference standard materials and are alternatively sampled by a laser beam, which is generated by an Nd–YAG pulsed laser (maximum energy of 3–4 mJ and at a maximum pulse frequency of 15 Hz) operating at 266 nm (quadrupled frequency). The diameter of the ablation crater ranges from 60 mmto100mm, and its depth is around 250 mm. Classic parameters are 70 s of ablation (20 s for pre-ablation and 50 s for analysis) and a 6–8 Hz laser shoot rate. The pre-ablation time of 20 s is set to eliminate the transient part of the signal and ensure that surface contamination or corrosion does not affect the results of the analysis. An argon gas flow carries the ablated aerosol to the injector inlet of the plasma torch, where the matter is dissociated, atomized and ionized (typical flow rate values range from 1.15 l min–1 to 1.35 l min–1, depending on the cell size). The ions are then injected into the vacuum chamber of a high-resolution system, which filters the ions depending upon their mass-to-charge ratio, and they are then collected by the channel electron multiplier or the Faraday cup. The measurements are carried out in peak jump acquisition mode, taking four points per peak for counting and analogue detection modes, and 10 points per peak for Faraday detection. Automatic detection mode is used for most of the elements; only sodium, silicon, aluminium and potassium are systematically detected with the Faraday detector. Silicon is measured on the 28 isotope and is used as an internal standard. With our analytical parameters, the scanning time necessary to measure the 38 selected isotopes is about 2 s. As most of the encountered isobaric interferences could be resolved by working on uninterfered isotopes, all the measurements are carried out in low-resolution mode. Two different standard reference materials are used to calculate the response coefficient factor

Ky as defined by Gratuze (1999) and thus to convert data into fully quantitative analyses: • The glass standard reference material (SRM) manufactured by NIST: SRM610. It is a soda– lime–silica glass doped with trace elements in the range of 500 ppm. Certified values are available for a very limited number of elements. Concentrations from Pearce, Norman and Hollocher (Hollocher and Ruiz 1995; Norman et al. 1996; Pearce et al. 1997) are used for the other elements. SRM610 is used to calculate all the Ky response coefficient factors except for magnesium, potassium and iron, which are present at levels that are too low, and aluminium, the value of which is not certain enough.

Table 1

Volcanic complexes Number Subgroups Location Number Samples and obsidian of of provided by outcrops samples samples Geochemical groups

Georgia Chikiani (Paravani, 7 Southern flank 2 Authors Kojun Dag) Northern flank 2 North-east flow 3 Armenia Ashotsk (Eni-Ël, 3 Aghvorik (= Eni-Ël) village 3 Authors Kechut) Tsaghkunyats 8 Tsaghkunyats 1 Damlik 3 Authors Ttvakar 2 Tsaghkunyats 2 Kamakar 2 Authors Aïkasar 1 Akhurian River 3 Akhurian 1 Near Shirakavan 1 Authors (= Sarikamis (Sarikamis NW) North) Akhurian 2 Near Shirakavan 2 Authors (Sarikamis NE) Arteni 7 Arteni 1 Satani Dar 1 Authors Mets Arteni 1 Arteni 2 Pokr Arteni 2 Authors Aragats flow 1 Arteni 3 Pokr Arteni 1 Authors Aragats flow 1 Gutansar 7 Dzhraber 3 Authors Fontan 1 Alapars 1 Gjumush 1 Aivazan 1 Hatis (Atis) 4 Hatis 1 Akunk (south-west) 2 Authors Kaputan (north-west) 1 Hatis 2 Zerborian (south-east) 1 Authors Gegham 7 Spitaksar, 3 Authors Geghasar 4 Vardenis 1 Khorapor 1 Authors Syunik 8 Syunik 1 Bazenk 2 Authors Syunik 2 Mets Satanakar 1 Authors Syunik 3 Mets Sevkar 3 Authors Pokr Sevkar 2 Eastern Turkey Tendürek 9 From a flat area on the mountain 9 M. D. Glascock Meydan Dag 4 On the outcrops, south-east of the 3 C. Kuzucuoglu summit caldera and C. Marro Concentration of blocks, on the 1 south-east flank of the volcano Süphan Dag 9 2 km east of Harmantepe 2 M. D. Glascock 5 km east of Harmantepe 4 3 km north of Mum village 3 Sarikamis 3 Sarikamis 1 Along the road from Karakurt to Sarikamis 1 M.-C. Cauvin South Sarikamis region 1 Sarikamis 2 Along the road from Karakurt to Sarikamis 1 M.-C. Cauvin

• Corning glass B. This glass was designed to match the compositions of ancient plant ash glass (Verità et al. 1994; Brill 1999, vol. 2, p. 544; Bronk and Freestone 2001; Vicenzi et al. 2002; Dussubieux et al. 2009). Corning B is mainly used to calculate response coefficient factors for sodium, magnesium, aluminium, potassium, calcium, titanium, manganese, iron, strontium and barium. The reference values used for these standards are given in the table of results obtained for the different obsidian compositional groups. Each analysis consists of a blank measurement followed by two ablations located at different places on the object. To improve reproducibility and to correct eventual instrumental drifts or changes in the ablation efficiency, both standards are systematically analysed at the beginning and at the end of the sequence, and every six or eight samples. Concentrations are calculated using net average intensity counts rates measured for each isotope. A simplified version of the internal standard calculation method developed by Gratuze (1999) and used by different authors has been adapted to this analytical protocol. The following formula is used to calculate concentrations for all elements, assuming that the sum of their contents in weight per cent in obsidian is equal to 100%: ∗αα∗ = ⎛ IYY⎞ ⎛ IXX⎞ %,YOmn ⎝ ⎠ ⎝ ∑ ⎠ IKSi∗ Y IKSi∗ X where IY, IX and ISi are the net intensities counts rates, corrected for isotopic abundance, measured for elements Y, X and silicon; aY and aX are the conversion factors from element to oxide for elements Y and X; and KY and KX are the response coefficient factors for elements Y and X, calculated as follows:

I∗[] Conc K = Ystd Sistd , Y ∗[] ISistd Conc Ystd where IYstd and ISistd are the net intensities counts rates, corrected for isotopic abundance, measured for element Y and silicon in the standard material and [Conc]Ystd and [Conc]Sistd are the concentrations of element Y and Si in the standard material. The experimental detection limits calculated on the basis of a peak intensity equal to three times the standard deviation of the average value of the background intensity range from 0.07% to 0.002% for minor elements and from a few ppb to 10 ppm for others (Table 2). Accuracy and reproducibility are difficult terms to estimate when dealing with archaeological material. These factors could only be estimated by using reference materials, and by measuring the difference between certified values and calculated values for the accuracy and the deviation measured on the average response coefficient factor K for reproducibility. Accuracy is estimated at 15 relative per cent for major and minor elements and 110 relative per cent for trace elements.

RESULTS AND DISCUSSION Twenty-two main different chemical groups of obsidian were obtained from the 14 volcanic complexes and secondary deposits that were studied. Different methods were used to represent compositional groups of obsidian. Depending on the authors, principal component analysis, hierarchical cluster analysis, extended rare earth element spidergrams or simple binary diagrams were used. In this work, we choose to use only

Table 2 The measured isotope, reference material used for standardization (*, N610 and Corning B; **, only Corning B, only N610 is used for other elements) and the range of detection limits achieved for obsidian characterization with the analytical protocol developed with the Element XR

Average range of lod values Elements

Below 10 ppb 141Pr, 159Tb, 165Ho, 169Tm, 175Lu, 181Ta, 232Th, 238U Between 10 and 25 ppb 89Y, 93Nb, 139La, 140Ce, 146Nd, 147Sm, 163Dy, 166Er, 172Yb, 178Hf Between 100 and 500 ppb 85Rb, 88Sr*, 90Zr, 133Cs, 153Eu Between 500 and 1000 ppb 66Zn, 157Gd Between 1 and 10 ppm 7Li, 11B, 47Ti*, 55Mn*, 137Ba* Between 25 and 50 ppm 24Mg**, 45Sc, 57Fe** Between 200 and 700 ppm 23Na*, 27Al**, 39K**, 44Ca*

lod, limit of detection. elements or element ratio binary diagrams, as they offer the possibility of rapidly comparing data obtained from different authors and different methods. The elements Rb, Sr, Y, Zr and Nb, which are the most utilized and determined elements (all these elements are determined by the main laboratories and portable methods such as portable non-destructive X-ray fluorescence) together with Ba (less often determined by portable methods) will be mainly used in our discussion. However, others elements such as rare earths may be also used to differentiate sources of close chemical compositions (Khalidi et al. 2010). Part of the data taken into account for the discussion was obtained between 2005 and 2009 with a PQXS quadrupole mass spectrometer, using the analytical protocol described in previous work (Gratuze 1999). All the samples were re-analysed at least once using the Element XR protocol described above. All these data are plotted on the various diagrams, which explains the large number of points compared to the small number of geological samples. Due to some calibration drifts between the two analytical proto- cols used (e.g., for elements such as zirconium), an artificial separation that tends to split the source into two close subgroups may appear on some diagrams. These types of subgrouping induced by an analytical bias will not be considered in the following discussion (e.g., the separation of Süphan Dag into two subgroups only correlated with the analytical protocol). In order to simplify the diagrams, the different obsidian flows emitted by the same volcanic complex will be represented as a whole on the main diagrams. They will, however, be split into their different subgroups in specific diagrams. For some sources, however, our geological samples do not match the entire compositional variability of the different obsidian flows generated by the volcanic complex. Some data published by other authors (Keller and Seifried 1990; Keller et al. 1996; Oddone et al. 1997; Gallet 2001; Delerue 2007) will therefore be used for these sources. As shown in the past by Cann and Renfrew (1964), barium and zirconium, and also the Nb/Zr and Y/Zr ratios (Gratuze 1999), together with strontium (Binder et al. 2011) remain the best parameters to distinguish the main obsidian sources (Figs 2–4). Thus, as shown in Table 3, all the outcrops studied could be distinguished by using three simple diagrams: barium versus zirconium, yttrium/zirconium versus niobium/zirconium and barium/zirconium versus barium/ strontium. If some of the volcanic complexes studied have a homogeneous composition (Gutansar, Khorapor), two or more subgroups could be defined for the other volcanic complexes and secondary deposits.

Chikiani (= Kojun Dag = Paravani) In southern Georgia, the Chikiani volcano (in Georgian, ‘the glass that glistens’), which reaches 2417 m, rises only ~300 m above the shores of the nearby lake Paravani. Its Turkish name, Kojun Dagh or ‘Cow Mountain’, adequately suggests the gentleness of the relief (Badalyan et al. 2004). The Chikiani obsidian is spread everywhere over the dome of the volcano and extends in a large flow to the north-east; this flow belongs to an eruptive phase dated to around 2.8 Ma, the southern part of the dome being about 400 ka younger (Le Bourdonnec et al. 2012). Obsidian is abundant and easy to access, the only limit to exploitation being the thick snow cover that lasts for more than 6 months. Moreover, the Khrami River, which receives many obsidian blocks from its tributaries that descend from the Chikiani slopes, carries numerous obsidian pebbles as far as its lower course, where sites of the Neolithic Shulaveri–Shomutepe culture, dated to the sixth millennium bc, are located (Badalyan et al. 2004). The quality of the obsidian is excellent—very homogeneous and without inclusions. Several varieties are found: uniform black, banded black and red, red–brown, mottled brown and black, mottled yellow and brown, and so on. The chemical analyses show that the samples taken from the Chikiani dome have an identical trace element chemical composition and form a single group characterized by low zirconium and high barium contents (Fig. 2). Concentrations of these elements are close to those of the Tsagh- kunyats obsidian. Their Nb/Zr andY/Zr ratios are similar to those defined for Gutansar and Hatis, and allow the distinction of two close subgroups (Fig. 3). However, this obsidian is completely differentiated from the other sources by using the Ba/Zr–Ba/Sr diagram (Fig. 4). As observed by Keller et al. (1996), there is a continuous variation of the Ba and Zr concentrations. The chronological studies have shown that there were several temporally successive flows between

1000 Arteni Ashotsk Hatis 800 Gegham Gutansar Chikiani 600 Akhurian/Sarikamis North Araxes/Sarikamis South Syunik Ba ppm 400 Tsaghkunyats Khorapor Süphan Dag 200 Tendürek Meydan Dag

0 0 100 200 300 Zr ppm

Figure 2 The binary diagram for the Zr–Ba contents of the outcrops studied.

0.7

0.6 Arteni Ashotsk 0.5 Hatis Gegham Gutansar 0.4 Chikiani Akhurian/Sarikamis North Y/Zr Araxes/Sarikamis South 0.3 Syunik Tsaghkunyats 0.2 Khorapor Süphan Dag Tendürek 0.1 Meydan Dag

0 0 0.5 1.0 1.5 2.0 Nb/Zr

Figure 3 The binary diagram of the Nb/Zr–Y/Zr ratios for the outcrops studied.

2.8 and 2.3 mya (Komarov et al. 1972; Badalyan et al. 2001; Lebedev et al. 2008) and these variations correspond to the progressive evolution of the magma.

Ashotsk (= Eni Ël = Kechut) The Ashotsk obsidian deposits are located in the south-western foothills of the Djavakheti range near the villages of Aghvorik (Eni-Ël range) and Sizavet, at about 2000 m a.s.l. The obsidian outcrops are rare and restricted on the surface, since the eruptions, which are dated from 2.6 (Komarov et al. 1972; Dzhrbashyan et al. 2001) to 1.1 mya (Oddone et al. 2000), have been covered by basaltic flows, on which vegetation has developed (Badalyan et al. 2004; Ollivier et al. 2010). The volcanic centres of the eruptions are not yet well defined (Keller et al. 1996). The Aghvorik and Sizavet obsidians are uniform black, blackish-brown to grey opaque, banded black and red. This obsidian is sufficiently high in quality for working; however, most of the raw material is small in size (10–15 cm in diameter on average), which limits its usefulness. The outcrops of Aghvorik and Sizavet are located 6–7 km from each another, but all the samples form a single homogeneous composition group. The Ashotsk obsidian is well separated from all the other groups on the different diagrams. They are characterized by high zirconium and barium contents and thus very low Nb/Zr and Y/Zr ratios.

60 Arteni Ashotsk 50 Hatis Gegham 40 Gutansar Chikiani Akhurian/Sarikamis North 30

Ba/Sr Araxes/Sarikamis South Syunik 20 Tsaghkunyats Khorapor Süphan Dag 10 Tendürek Meydan Dag 0 024681012 Ba/Zr

Figure 4 The binary diagram of the Ba/Zr–Ba/Sr ratios for the outcrops studied.

Tsaghkunyats The Tsaghkunyats range, which stretches north-east of the Aragats massif, contains several volcanoes with obsidian flows, which are the oldest in Armenia, dating back c. 4.5 mya (Oddone et al. 2000; Badalyan et al. 2001). From west to east, one encounters the obsidian deposits of Damlik (2781 m), Ttvakar, Kamakar, Arkayasar, Aykasar and Dalar (or Dallyar), with blocks of various sizes up to 1 m in diameter. These obsidian flows are relatively easy to access, since the slopes are not steep. Moreover, the Kasakh and Marmarik Rivers, which border the range, carry numerous obsidian boulders and pebbles that wash down from the mountain slopes after heavy rains. Thus, Hankavan, which is sometimes described as an obsidian deposit, is in fact the name of a village situated at the northern foot of the chain where numerous currents join together to form the Marmarik River. In the Kasakh River, obsidian pebbles were collected by the Neolithic human group living in the Kmlo cave: several artefacts have retained the cortex of the pebbles rolled down by the river (Chataigner and Gratuze 2013). The obsidian is mainly uniform black, sometimes red; banded black and red blocks are also found. The Tsaghkunyats obsidian forms two well-identified compositional groups according to their barium and zirconium contents, which are close to those of Chikiani obsidian (Fig. 2). These two groups are, however, identified and separated from Chikiani obsidian by their Nb/Zr–Y/Zr ratios as shown in Figure 5. In the first subgroup, we find the obsidian from Damlik and Ttvakar (referred to as Tsaghkunyats 1), and in the second one the obsidian from Kamakar and Aïkasar (referred to as Tsaghkunyats 2).

Table 3 Separated and overlapping outcrops according to the different diagrams

Source Zr–Ba diagram Nb/Zr–Y/Zr diagram Ba/Zr–Ba/Sr diagram

Arteni Split into three groups Split into two groups Split into three groups Ashotsk Separated Separated Separated Hatis Overlap with Süphan Dag, Overlap with Chikiani and Partial overlap with part of part of Sarikamis South Gutansar Tsaghkunyats and part of Chikiani Gegham Separated Separated Overlap with part of Syunik and Khorapor Gutansar Overlap with part of Overlap with Hatis and Separated Sarikamis South Chikiani Chikiani Overlap with Tsaghkunyats Overlap with Gutansar and Separated and part of Hatis Hatis Sarikamis North Split into two groups; Split into two groups; Split into two groups overlap with Meydan Dag overlap with Meydan Dag and Tendürek and Sarikamis South Sarikamis South Split into two groups; Split into two groups; Split into two groups overlap with Süphan Dag, overlap with Tendürek, Hatis and Gutansar Meydan Dag, Süphan Dag and Sarikamis North Syunik Split into three groups; one Separated Split into three groups; one of them overlaps with of them overlaps with Khorapor Khorapor and Gegham Tsaghkunyats Split into two groups; Split into two groups Split into two groups; overlap with Chikiani overlap with part of Hatis Khorapor Overlap with one of the Separated Overlap with Gegham and Syunik group part of Syunik Süphan Dag Overlap with Hatis and part Overlap with Sarikamis Separated of Sarikamis South South Tendürek Overlap with Meydan Dag Overlap with Sarikamis Overlap with part of Meydan and Sarikamis North North and South Dag Meydan Dag Overlap with Tendürek and Overlap with Sarikamis Overlap with part of Sarikamis North South Tendürek

Akhurian River (secondary deposit) and Sarikamis (primary deposits) In the valley of the Akhurian, at the conﬂuence of the Akhurian and Kars Rivers, an alluvial level, containing numerous obsidian pebbles, is visible in the section of the ancient terraces. This obsidian, dated to between 4.1 and 3.5 mya (Bigazzi et al. 1998), is of very good quality, but the pebbles are small (less than 10 cm in diameter). It varies in colour, being mainly uniform black, but also red or brown. According to the geologists, the Akhurian obsidian pebbles were brought by the Kars River. This river rises in the region of Sarikamis, where at least two generations of obsidian, separated by a time gap of about a million years, are present (Bigazzi et al. 1998; Poidevin 1998). The earliest episode (between 4.8 and 4.3 Ma) concerns a territory stretching more than 15 km south of the town (Sarikamis South), on the border of the Araxes Valley (Bigazzi et al. 1998): the dome of Ciplak Dag (outcrops close to the village of Mescliti and along the road between Karakurt and Sarikamis) and the Ortatepe dome (outcrops close to Sehitemin; Sevindi 2003). The latest

0.25

Chikiani 0.20

Damlik 0.15 Tvakar Y/Zr 0.10 Kamakar

Aïkasar 0.05

0 0 0.2 0.4 0.6

Nb/Zr

Figure 5 The binary diagram of the Nb/Zr–Y/Zr ratios for the Chikiani and Tsaghkunyats outcrops. episode (between 3.8 and 3.5 Ma) is attested by two obsidian outcrops located closer to the town (Sarikamis North), near the villages of Handere and Hamamli. In order to check the hypothesis of an origin in the region of Sarikamis, on the next diagrams we compare the Akhurian River samples with those from the Sarikamis South outcrops, and with values published by other authors for the different Sarikamis obsidian deposits (Keller and Seifried 1990; Keller et al. 1996; Gallet 2001; Delerue 2007) (Figs 6 and 7). From these diagrams, it appears that the first chemical group defined for the Akhurian River (Akhurian 1) matches the composition of the Handere obsidian outcrops, while the Akhurian 2 group matches the composition of the Hamamli outcrops. All these obsidians belong to the Sarikamis North sources. In the same way, our Sarikamis South 1 group appears to be close of the Sarikamis 1 group defined by Keller, while our Sarikamis South 2 group matches the composition of the Mescitli/ Sehitemin outcrops and appears to be close to the Sarikamis 2 group defined by Keller. All these obsidians belong to the Sarikamis South sources. The Ba/Zr versus Ba/Sr diagram appears to be the stronger in differentiating these different outcrops (Fig. 7). It then appears that the Shirakavan pebbles have the same composition as other pebbles found in the Kars River near Akbaba Dag and that this composition is characteristic of the Sarikamis North obsidian deposits, which are situated at the springs of the Kars River (Gallet 2001). Thus the chemical analyses confirm the hypothesis that these obsidian pebbles were carried down by the Kars River.

Arteni complex The Arteni complex is located in the south-western part of the Aragats volcanic massif. Two major eruption centres—Mets (Big) Arteni (2047 m) and Pokr (Small) Arteni (1753 m)— represent a multiphase volcanic ﬁeld formed by repeated eruptions of rhyolitic magmas. The prominent example is the 7–8 km long Aragats ﬂow of Mets Arteni, which is dominantly perlitic,

600 Hatis

Gutansar 500 Akhurian 1 Handere

Akhurian 2 Hamamli 400 Handere (Delerue 2007)

Handere (Gallet 2001) 300

Ba ppm Hamamli (Gallet 2001)

200 Sarikamis 1

Sarikamis 2

100 Mescitli and Sehitemin (Delerue 2007)

Mescitli (Gallet 2001)

0 Sarikamis 1 (Keller and Seifried 1990) 0 50 100 150 200 250 300 Zr ppm Sarikamis 2 (Keller and Seifried 1990)

Figure 6 The binary diagram for the Zr–Ba contents of Akhurian obsidian and the obsidian outcrops sampled in the region of Sarikamis. with parts of the flow solidified as obsidian. Obsidian blocks occur also in the pumice deposits of the earliest phases of Arteni volcanism, such at Brusok (Keller et al. 1996). Satani Dar (Tapak Bloor) was formed as a result of one of the separate volcanic eruptions (Blackman et al. 1998). The dates show that the different sources were formed successively between 1.4 and 1.1 mya (Komarov et al. 1972; Wagner and Weiner 1987; Oddone et al. 2000; Badalyan et al. 2001; Chernyshev et al. 2006). The Arteni obsidians range from uniform opaque black to opaque grey, grey–brown, red, banded black and red, and translucent. The material is very abundant and of the highest quality. Several different compositional groups, which appear to be comagmatic, were obtained for the Arteni obsidian outcrops (Fig. 8). This volcanic complex thus appears to be one of the more difficult ones to characterize. Three main chemical groups could be derived from our data and from those published by Keller (Keller and Seifried 1990; Keller et al. 1996). The first (Arteni 1), characterized by low barium and zirconium concentrations, is equivalent to the Arteni 1A defined by Keller. The obsidian from this group comes from the outcrops of Satani Dar and Mets Arteni. The second group, characterized by higher barium concentration, is equivalent to Keller’s Arteni 1B group as defined in 1990, but not in 1996. The last group, which contains the highest amount of barium, corresponds to Keller’s Arteni 1C group. The latter two groups contain obsidian that originates from both the Pokr Arteni and Aragats flow, this is probably due to an error in sampling, as these flows are difficult to distinguish in the field. Therefore a new systematic sampling and a new set of analyses would be necessary.

30 Hatis

Gutansar 25 Akhurian 1 Handere

Akhurian 2 Hamamli 20 Handere (Delerue 2007)

Handere (Gallet 2001) 15 Ba/Sr Hamamli (Gallet 2001)

Sarikamis 1 10 Sarikamis 2

Mescitli and Sehitemin (Delerue 2007) 5 Mescitli (Gallet 2001)

Sarikamis 1 (Keller and Seifried 1990) 0 0246810Sarikamis 2 (Keller and Seifried 1990) Ba/Zr

Figure 7 The binary diagram of the Ba/Zr–Ba/Sr ratios of Akhurian obsidian and the obsidian outcrops sampled in the region of Sarikamis.

400

350

300 Arteni 1, Satani Dar and Mets Arteni 250 Arteni 2, Pokr Arteni and Aragats flow 200 Arteni 3, Pokr Arteni and Aragats flow Ba ppm Ba 150 Arteni 1A (Keller) 100 Arteni 1B (Keller) 50 Arteni 1C (Keller) 0 020406080 Zr ppm

Figure 8 The binary diagram of the Zr–Ba contents for the Arteni outcrops; comparison with data published by Keller (Keller and Seifried 1990; Keller et al. 1996).

Gutansar complex The Gutansar complex is found to the north of Yerevan and covers a large area between the volcano itself and the left bank of the Hrazdan River, which flows from Lake Sevan towards the Araxes. This complex contains several volcanic domes (Gutansar, Fontan, Alapars, Aivazan, Dzhraber and Gyumush) that erupted during a relatively short period between 310 000 and 240 000 years ago (Wagner and Weiner 1987; Oddone et al. 2000; Badalyan et al. 2001, 2004). The Gutansar samples present a wide range of colours from uniform black to grey, grey– brown, brown, banded black and red, mottled black and red. The flows are very abundant and contain enormous blocks of obsidian of usually high quality. All the obsidian from the Gutansar complex forms a homogeneous chemical group that is easily distinguished from the other Armenian obsidian groups in terms of their zirconium and barium concentrations. We notice just a slight overlap with the Sarikamis 2 group of obsidian, which is easily resolved by using their Ba/Zr–Ba/Sr ratios (Fig. 7). The chemical analyses confirm the exceptional homogeneity of the different Gutansar sources, making it practically impossible to distinguish among them, given the margin of error that accompanies the analytical results. A flow from the Gutansar volcano spread south-east as far as the foot of the Hatis volcano, which is 6 km away. Samples collected in this region have been attributed alternatively to Hatis and to Gutansar. However, the chemical compositions, which are quite distinct, make it possible to correct the geological origins of these samples.

Hatis (or Atis) At Mt Hatis (2529 m), at least two phases of activity have been recognized: (a) approximately 700 ka ago, the formation of the Hatis volcano—the composition of the obsidian corresponds to calc-alkaline rhyolites; (b) about 50 ka ago, the intrusion of small obsidian dykes that cross-cut acid volcanic rocks produced earlier (Arutyunyan et al. 2007). Poidevin (1998) has distinguished three subgroups: Hatis I and Hatis II belong to the first phase of activity; while Hatis III, a vitreous rhyolite enriched in rare earth elements, belongs to the second phase. The obsidian is grey to grey–brown on the south-western flank and black on the southern slope (Blackman et al. 1998). The Hatis III samples contain some mineral inclusions (feldspars) that are visible to the naked eye; these samples are not suitable for knapping (Pitois 1998; Badalyan et al. 2004). The obsidian from the Hatis Mountain is represented by two groups that are easily differentiated by their strontium content. The first one (Hatis 1), with lower strontium concentrations (about 81 ppm), originates in the western outcrops (Akunk and Kaputan), while the second one (Hatis 2), with higher strontium contents (136 ppm), comes from the south-eastern slopes (Zerborian).

Gegham Mountains (Geghasar, Spitaksar) Spitaksar (3560 m) and Geghasar (3446 m) are large volcanic domes that are located in the southern part of the Gegham volcanic highland and are about 6 km apart. In volcanic structure, eruptive mechanisms, products and age, the two volcanoes show strong similarities. The obsidian ﬂows spread along the ﬂanks of the domes and at their feet, on the high plateaus that are located at ~3000–3200 m and covered with steppic vegetation. These plateaus are densely populated

50 Gegham

40 Khorapor

Bazenk 30

Mets Satanakar

Ba ppm Ba 20 Pokr Sevkar and Mets Sevkar

0 0 50 100 Zr ppm

Figure 9 The binary diagram for the Zr–Ba contents of the Syunik, Khorapor and Gegham outcrops. during the summer by transhumant herders who come there to put their herds out to pasture, but are inaccessible from mid-October to the end of May, because of a stable snow cover that is about 2 m thick on average. However, a mountain stream has its source at the very foot of Geghasar on its north-west flank and carries numerous blocks of obsidian towards the Azat River, where they are deposited and then carried further to the south and to the Ararat plain. These obsidian flows are the most recent in Armenia and are dated to between 80 000 and 40 000 years ago for Geghasar and 120 000 years ago for Spitaksar (Komarov et al. 1972; Badalyan et al. 2001). Macroscopically, the obsidians from Geghasar and Spitaksar are very different. At Geghasar, the obsidian presents various colours (translucent, uniform grey, red, banded brown and black). At Spitaksar, the obsidian contains numerous crystalline inclusions, which make it more difficult to work because the small crystals block the waves of force transmitted by percussion, and the forms of the flakes detached are problematic. The obsidians from Geghasar and Spitaksar form a homogeneous chemical group. The diffi- culty in distinguishing between them on the basis of their composition indicates that they originate from the same magmatic chamber and that they evolved very little during the 40 000 years or so that separated the two volcanic eruptions. This obsidian is characterized by very low zirconium and barium values (Figs 2 and 9), but is easily differentiated from the Syunik and Khorapor obsidians in terms of their Nb/Zr and Y/Zr ratios (Fig. 3).

Khorapor (Vardenis) Located on the northern slopes of the Vardenis range, south-east of Lake Sevan, Khorapor is a dome-shaped volcano. Reaching an elevation of 2906 m, it rises in a region of high plateaus, which it overlooks by only a few hundred metres. This highland region is covered by snow from mid-November to the end of May; thus the volcano is accessible only during the summer. The obsidian, dated from 1.75 to 1.53 Ma (Komarov et al. 1972; Badalyan et al. 2001), is found both at the summit of the dome and on the ﬂanks of the volcano.

Gegham

50 Khorapor

Bazenk 40

Ce ppm Ce Mets Satanakar

30 Pokr Sevkar and Mets Sevkar

20 10 20 30 La ppm

Figure 10 The binary diagram for the La–Ce contents of the Syunik, Khorapor and Gegham outcrops.

This obsidian is of poor quality to work, since it contains many crystalline inclusions and generally consists of small nodules within a rhyolitic matrix. No artefacts have been found on this deposit. The obsidian from Khorapor is close in composition to those from the Gegham Mountains and from the Syunik complex (Figs 9 and 10). They could, however, be differentiated on the basis of their Nb/Zr and Y/Zr ratios (Fig. 3).

Syunik complex (Satanakar group, Sevkar group and Bazenk) The Syunik sub-zone involves large volcanoes of distinct morphology, including Mets Satanakar, Michnek Satanakar, Pokr Satanakar, Mets Sevkar, Pokr Sevkar (or Sevkar foothills) and Bazenk. The longest and thickest flows are those at Mets Sevkar and in ‘the foothills of Pokr Sevkar’. This latter term is used because the obsidian deposit is near the dome of Pokr Sevkar, but more recent deposits of basalt cover most of the surrounding landscape and the relation of the obsidian to Pokr Sevkar is uncertain. One hypothesis is that this deposit was part of the great flow emitted in this direction by Mets Sevkar (Badalyan et al. 2004). The mountain streams that descend from these high plateaus and join the Vorotan River carry blocks of obsidian; in the valley, many obsidian pebbles can be collected from the river. At Godedzor, about 30 km from the obsidian outcrops, a certain number of artefacts bear strips of neo-cortex (surface ground down by movement in the river) and the reduced size of most of them shows that the pebbles found in the Vorotan were actually exploited by the Chalcolithic inhabitants of this settlement. The Syunik sources (Satanakar, Sevkar and Bazenk), date from 0.61 to 0.43 Ma (Komarov et al. 1972; Badalyan et al. 2001). The obsidian, abundant and of high quality, is dark grey to jet black and translucent when thinly flaked; at the Sevkar sources, there are significant occurrences of red–brown mottling (Cherry et al. 2008).

The obsidian from the Syunik complex forms three close chemical groups (Fig. 9), which correspond, respectively, to the outcrops of Bazenk (Syunik 1), Mets Satanakar (Syunik 2) and Mets Sevkar and Pokr Sevkar (Syunik 3). These groups can be discriminated on the basis of their concentrations of the lighter rare earth elements (especially La and Ce) and Th (Cherry et al. 2008) (Fig. 10). As stated above, the obsidian from Bazenk shows some chemical similarities with the Gegham Mountains obsidian.

Tendürek Tendürek is an isolated polygenetic volcano (3584 m), built by small fissure eruptions followed by central eruptions and caldera collapse. The rocks are predominantly basalts and trachyandes- ites; however, a small obsidian flow (30 cm thick) is mentioned between two trachytic eruptions (Yilmaz et al. 1998). This obsidian flow is visible on the northern flank of the volcano, at about 15 km south-west of the city of Dogubeyazit. Very few samples from the Tendürek have been analysed so far (Frahm 2010). All the obsidian samples provided by M. Glascock come from a single flat area on the eastern flank of the Tendürek. This deposit is distinct from the outcrop mentioned by Yilmaz et al. (1998) on the northern flank.

Meydan Dag The Meydan Dag (2722 m) strato-volcano is Pliocene in age and is characterized by a summit caldera, the south-eastern rim of which is interrupted by a Middle Pleistocene obsidian dome, from which an obsidian lava flow originates, presenting a 5-km-wide front. The south-eastern flank of the volcano, east of the road coming down from the caldera above the village of Ziyaret, is scattered with obsidian blocks (Belli 2001). The obsidian is almost devoid of any microcrysts. It is black and brown (Matsuda 1988). The obsidian that comes from the Tendürek and that from the Meydan Dag volcanoes are close in terms of their Sr,Y, Zr, Nb and Ba compositions, but they could be easily differentiated by their iron and rubidium contents (Table 4, first part).

Süphan Dag The Süphan Dag (4434 m), which represents the second highest elevation in Turkey, is located at the intersection of two major faults. It is a polygenetic strato-volcano made up of a complex of many eruptive domes and cones with intercalated lava ﬂows and pyroclastics, the lavas ranging in composition from basalt to rhyolite. The most recent products consist of obsidian domes and lava ﬂows, dated to about 0.7 Ma (Pearce et al. 1990; Bigazzi et al. 1998). They are located on the north and south-western part of the main zone. Mount Nernek, situated to the south of Mount Süphan, has also produced obsidians, together with rhyolitic and perlitic lavas (Ercan et al. 1996). The obsidian from the Süphan Dag volcano has a dark-grey colour, which is due to an exceedingly thick felt of acicular iso-oriented crystal. White oligoclase inclusions and well- formed opaque tabular crystals, sometimes visible to the naked eye, are widespread (Fornaseri et al. 1975–7). The obsidian samples provided by M. Glascock come from three different places near to Harmantepe (south-west of the volcano).

Table 4 Average compositions and standard deviations for each compositional group. The number of samples analysed for each group is given in brackets. Reference values used for Nist and corning glass standard are given in

the two ﬁrst lines. All elements are in ppm, except for Na2O, MgO, Al2O3, SiO2,K2O and CaO, which are given as % oxides

Source Li B Na2O MgO Al2O3 SiO2 K2O CaO Ti Mn Fe Zn Rb Sr Y Zr Nb

Nist 610 glass Reference 484 351 13.4 0.08 2.0 69.9 0.06 11.6 434 433 457 456 431 497 450 440 419 values Corning B glass Reference 105 17.0 1.03 4.4 62.3 1.00 8.6 630 1 936 2 378 1526 161 values Arteni 1 Average (18) 69.3 44.3 4.29 0.05 13.6 75.4 4.09 0.54 331 687 3 281 46.2 143 7.9 21.1 35.9 36.3 Satani Dar and SD 4.6 3.6 0.24 0.002 1.2 0.8 0.17 0.06 15 40 433 6.8 7 0.7 1.7 3.1 2.5 Mets Arteni Arteni 2 Average (13) 55.9 41.2 3.98 0.06 13.1 76.2 4.23 0.59 440 542 3 850 39.2 122 14.3 15.7 48.4 28.2 Pokr Arteni and SD 3.4 3.9 0.21 0.003 0.3 1.2 0.19 0.07 33 43 209 3.9 10 1.3 0.7 2.6 1.8 Aragats ﬂow Arteni 3 Average (7) 50.8 42.6 4.03 0.08 13.1 76.0 4.39 0.63 526 514 4 179 50.5 122 22.6 14.6 52.0 25.9 Pokr Arteni and SD 4.6 9.1 0.01 0.03 0.1 1.1 0.11 0.08 29 31 420 13.2 3 2.6 1.7 7.7 0.7 Aragats ﬂow Ashotsk Average (8) 31.2 22.9 4.16 0.37 15.2 72.6 4.01 1.42 1 855 412 11 766 42.0 94 142.7 12.2 192 17.7 SD 2.6 4.4 0.14 0.02 0.7 0.5 0.13 0.06 65 39 756 5.9 5 5.7 1.4 25 1.3 Hatis 1 Average (8) 49.3 27.6 4.32 0.18 14.1 75.3 3.88 0.99 626 462 6 184 36.8 108 81.7 10.4 62.7 21.4 SD 4.4 7.0 0.13 0.02 0.2 0.2 0.07 0.11 18 26 924 3.7 7 5.6 0.8 3.7 1.7 Hatis 2 Average (8) 54.4 26.0 4.24 0.40 15.0 73.8 3.70 1.45 1 027 462 9 839 38.0 92 133.9 10.0 86.2 19.9 SD 4.7 4.9 0.08 0.01 0.4 0.8 0.04 0.10 41 35 558 4.7 8 6.8 0.6 6.3 1.0 Gegham Average (20) 80.3 44.6 4.27 0.05 13.5 76.0 4.22 0.59 373 604 3 515 31.2 191 6.6 15.4 42.4 47.2 SD 8.6 5.2 0.10 0.01 0.4 0.9 0.07 0.07 19 73 353 4.2 13 0.9 1.9 5.3 3.5 Gutansar Average (24) 63.6 30.9 4.34 0.22 14.6 74.7 3.80 0.94 1 002 566 8 048 40.9 137 87.3 15.3 121 33.5 SD 8.0 5.5 0.20 0.02 0.7 0.5 0.09 0.10 71 51 943 5.9 9 12.2 1.8 13 2.2 Chikiani Average (19) 44.9 25.4 4.08 0.10 13.5 76.0 4.42 0.68 605 443 4 922 48.2 127 54.8 9.1 60.1 18.4 SD 13.1 3.4 0.17 0.01 0.6 0.6 0.11 0.16 53 17 511 11.9 6 5.5 0.8 5.8 1.6 Sjunik 1 Average (6) 73.1 18.8 4.22 0.04 13.5 76.9 4.07 0.46 370 471 4 946 34.1 174 3.0 5.9 60.8 34.9 Bazenk SD 10.5 3.6 0.36 0.01 0.3 0.6 0.23 0.08 18 15 2 341 1.6 15 0.6 0.5 7.6 2.2 Sjunik 2 Average (2) 72.8 23.6 4.16 0.05 12.8 77.0 4.24 0.49 484 510 4 696 46.0 193 5.6 6.5 57.2 34.8 Mets Satanakar SD 3.3 3.2 0.19 0.004 0.5 0.5 0.26 0.05 9 182 1 0.1 0.8 1.0 0.1 Sjunik 3 Average (13) 56.6 25.3 4.08 0.05 13.3 76.1 4.20 0.54 522 391 4 260 31.4 167 11.3 6.5 63.6 30.0 Mets Sevkar/ SD 5.1 4.1 0.08 0.002 0.2 1.1 0.05 0.06 40 22 286 7.5 8 0.9 0.7 3.9 1.9 Pokr Sevkar Tsakhkunjats 1 Average (10) 45.4 26.3 4.28 0.12 13.4 75.8 4.20 0.86 612 437 5 622 32.4 103 115.9 6.1 64.6 20.5 Damlik/Ttvakar SD 3.9 3.9 0.12 0.01 0.3 0.6 0.09 0.05 48 31 914 1.4 9 18.5 1.0 10.7 2.0 Tsakhkunjats 2 Average (10) 34.0 22.4 4.22 0.18 14.3 74.9 4.12 0.88 842 377 7 613 33.5 84 175.1 6.2 111 18.5 Aïkasar/ SD 5.0 3.5 0.23 0.01 0.6 0.5 0.09 0.09 41 36 403 3.1 6 18.3 0.6 9 0.4 Kamakar Khorapor Average (1) 86.8 39.3 4.04 0.04 12.6 77.7 4.38 0.67 483 4 349 205 2.1 11.4 67.3 35.9 SD Akhurian 1 Average (2) 50.3 27.9 4.79 0.06 13.2 76.0 4.21 0.44 583 650 7 120 67.1 136 6.0 31.5 143 26.1 Handere SD 2.5 0.1 0.01 0.01 0.7 0.6 0.05 0.06 9 17 3 0.8 2.5 14 1.0 Akhurian 2 Average (12) 51.6 26.5 4.50 0.03 15.4 74.3 4.13 0.31 474 603 7 633 72.2 130 2.0 35.4 168 26.9 Hamamli SD 8.0 1.9 0.24 0.004 1.6 1.3 0.09 0.05 44 22 539 5.9 5 0.7 3.1 18 1.3 Sarikamis 1 Average (7) 46.4 29.8 3.89 0.10 13.2 76.6 4.49 0.49 792 236 7 147 26.7 135 16.5 19.2 106 14.7 SD 6.2 1.7 0.14 0.004 0.3 0.3 0.09 0.07 120 35 1 246 2.5 16 2.1 1.4 6 1.1 Sarikamis 2 Average (7) 37.2 23.0 3.80 0.06 15.0 75.6 4.19 0.41 478 337 4 789 32.1 121 16.8 16.2 70.2 12.4 Mescitli/ SD 4.4 2.1 0.26 0.004 1.8 1.4 0.20 0.04 62 47 775 4.8 9 1.7 1.0 10.8 0.5 Sehitemin Süphan Dag Average (11) 65.5 45.7 4.02 0.04 13.0 75.9 4.23 0.48 430 219 11 725 44.2 128 9.3 19.0 72.7 8.5 SD 2.7 1.4 0.19 0.001 0.4 0.9 0.15 0.04 39 27 3 318 2.4 25 1.6 1.6 11.4 0.3 Tendürek Average (9) 74.4 30.9 4.89 0.05 13.0 75.2 3.63 0.34 431 481 16 333 87.6 122 6.9 26.1 168 23.5 SD 9.1 2.5 0.09 0.004 0.5 0.5 0.37 0.03 24 27 937 0.7 3 0.7 3.5 20 1.4 Meydan Dag Average (10) 89.4 40.4 4.59 0.05 13.5 76.0 3.95 0.36 448 477 9 564 75.5 183 11.8 43.4 230 32.3 SD 12.7 12.0 0.09 0.005 0.3 0.4 0.03 0.05 31 31 726 13.3 18 3.2 11.1 48 3.8

Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta Th U Ba/Zr Ba/Sr Nb/Zr Y/Zr

361 424 457 448 430 431 451 461 420 443 427 449 426 420 462 435 418 377 451 457

660

4.2 30.1 8.4 23.1 2.2 8.1 2.9 0.26 3.1 0.65 4.4 0.92 2.7 0.43 3.2 0.44 2.2 2.3 11.6 8.8 0.84 3.8 1.02 0.59 0.4 4.0 0.9 1.8 0.2 1.0 0.4 0.3 1.3 1.1 0.09 0.3 0.09 0.03

3.4 142 12.2 29.2 2.5 8.9 2.2 0.25 2.1 0.41 2.7 0.58 1.7 0.27 2.0 0.27 2.3 1.8 11.2 7.4 2.94 10.0 0.58 0.32 0.3 10 0.9 1.5 0.1 0.8 0.1 0.06 0.1 0.05 0.1 0.03 0.1 0.04 0.1 0.04 0.2 0.1 1.0 0.9 0.21 0.5 0.02 0.01

3.4 274 14.6 34.5 2.9 9.9 2.2 0.36 2.1 0.44 2.5 0.57 1.6 0.32 1.9 0.30 2.4 1.5 10.9 7.1 5.31 12.2 0.51 0.28 0.4 31 1.4 1.9 0.2 0.6 0.6 0.2 1.5 0.7 0.43 0.6 0.08 0.03

2.3 752 41.8 71.3 6.1 21.3 3.4 0.85 2.7 0.41 2.5 0.52 1.6 0.25 1.8 0.30 5.5 1.1 15.8 3.8 3.97 5.3 0.09 0.06 0.3 25 2.4 3.5 0.2 1.6 0.2 0.02 0.2 0.02 0.3 0.05 0.2 0.01 0.2 0.01 0.7 0.1 2.8 0.4 0.58 0.3 0.01 0.00

4.4 450 21.2 41.4 3.4 11.5 2.0 0.47 1.7 0.29 1.8 0.39 1.2 0.19 1.4 0.20 2.6 1.8 13.5 10.1 7.20 5.5 0.34 0.17 0.4 24 1.2 1.7 0.2 0.8 0.1 0.2 2.1 1.1 0.53 0.3 0.02 0.02 3.4 465 24.6 45.6 3.8 13.1 2.1 0.45 1.8 0.30 1.9 0.40 1.2 0.18 1.4 0.21 2.8 1.6 13.6 8.2 5.42 3.5 0.23 0.12 0.4 41 1.8 3.9 0.3 1.0 0.1 0.07 0.1 0.02 0.1 0.03 0.1 0.01 0.0 0.01 0.3 0.1 1.1 0.7 0.68 0.4 0.01 0.01 7.2 8.7 12.4 28.2 2.4 8.7 2.2 0.16 2.0 0.40 2.7 0.56 1.7 0.26 2.0 0.28 2.1 3.9 19.5 15.5 0.21 1.3 1.13 0.37 0.8 0.9 0.9 1.5 0.2 0.7 0.1 0.01 0.1 0.03 0.2 0.05 0.2 0.01 0.2 0.03 0.4 0.4 3.6 2.3 0.04 0.2 0.17 0.06 5.0 363 24.9 50.3 4.2 14.3 2.7 0.48 2.3 0.43 2.9 0.59 1.8 0.29 2.3 0.33 3.9 2.5 14.3 10.4 3.03 4.2 0.28 0.13 0.6 25 2.7 3.5 0.5 1.2 0.2 0.04 0.2 0.03 0.3 0.05 0.2 0.03 0.2 0.03 0.5 0.2 1.9 1.0 0.19 0.4 0.02 0.01 4.4 543 17.8 39.1 3.4 11.4 2.1 0.53 2.1 0.33 1.8 0.36 1.1 0.16 1.2 0.17 2.4 1.4 11.6 6.2 9.08 9.9 0.31 0.15 0.5 65 2.0 3.5 0.3 1.0 0.1 0.09 0.4 0.04 0.2 0.04 0.1 0.02 0.1 0.01 0.2 0.2 1.6 0.5 1.13 0.5 0.04 0.02 4.9 3.3 14.1 26.0 2.0 4.7 0.6 0.05 0.5 0.09 0.6 0.16 0.6 0.12 1.1 0.17 3.2 2.0 27.8 12.7 0.06 1.2 0.58 0.10 0.8 0.5 1.0 1.5 0.1 0.2 0.1 0.01 0.0 0.00 0.0 0.01 0.0 0.01 0.1 0.01 0.4 0.1 5.4 1.3 0.01 0.4 0.04 0.02 5.0 12.7 21.0 38.5 2.6 7.0 0.9 0.09 0.7 0.14 0.8 0.18 0.6 0.13 1.1 0.18 2.6 1.9 26.8 12.7 0.22 2.3 0.61 0.11 0.3 0.2 0.8 0.2 0.2 2.1 0.00 0.1 0.01 0.02 4.3 31.6 24.3 46.7 3.1 8.7 2.7 1.6 23.8 10.9 0.50 2.8 0.47 0.10 0.5 4.0 1.6 2.6 0.2 1.1 0.5 0.2 1.9 1.4 0.05 0.2 0.02 0.01 3.5 586 28.3 53.7 4.2 12.7 1.8 0.25 1.2 0.22 1.1 0.26 0.6 0.15 0.9 0.14 2.5 1.5 21.8 11.3 9.12 5.1 0.32 0.10 0.4 76 4.4 5.2 0.5 1.4 0.4 0.1 5.3 1.8 0.35 0.2 0.04 0.02

2.8 895 43.9 74.0 5.6 16.3 2.0 0.43 1.2 0.19 1.1 0.22 0.7 0.11 0.9 0.14 3.1 1.2 24.5 9.0 8.08 5.2 0.17 0.06 0.4 38 2.7 3.8 0.4 1.3 0.1 0.04 0.1 0.02 0.1 0.02 0.0 0.01 0.1 0.02 0.3 0.1 2.6 0.3 0.53 0.5 0.01 0.00 6.8 2.0 18.8 36.1 28.2 17.0 0.03 0.9 0.53 0.17

4.4 95.1 31.0 70.0 6.3 23.4 5.2 0.43 4.9 0.92 6.1 1.26 3.9 0.65 4.4 0.62 5.5 1.6 15.1 6.9 0.67 15.9 0.18 0.22 0.3 11.4 4.3 1.3 2.3 0.8 0.02 0.3 0.01 0.00 4.4 29.3 33.1 68.2 6.4 23.5 5.2 0.25 4.8 0.91 6.0 1.29 3.8 0.57 4.4 0.66 5.6 1.5 16.8 6.8 0.18 15.8 0.16 0.21 0.7 5.3 7.3 13.5 1.3 4.3 0.7 0.06 0.6 0.08 0.4 0.09 0.2 0.05 0.4 0.06 0.4 0.1 1.7 0.6 0.04 4.0 0.02 0.03 4.4 287 27.4 52.9 4.8 14.4 2.9 0.24 2.5 0.45 3.0 0.69 2.0 0.33 2.5 0.38 4.1 1.1 20.6 8.8 2.70 17.5 0.14 0.18 0.2 30 4.6 2.7 0.4 1.5 0.0 0.01 0.0 0.01 0.0 0.05 0.1 0.01 0.0 0.00 0.7 0.0 4.2 0.9 0.22 2.0 0.01 0.02 4.0 391 21.8 40.1 3.6 12.5 2.4 0.32 2.3 0.39 2.6 0.57 1.7 0.23 2.1 0.30 2.8 0.9 15.6 6.8 5.64 23.4 0.18 0.23 0.2 41 4.6 4.5 0.4 1.5 0.3 0.05 0.2 0.05 0.3 0.06 0.1 0.04 0.2 0.05 0.4 0.0 3.5 1.0 0.80 2.8 0.03 0.02 4.2 389 19.7 43.6 4.1 17.2 3.8 0.35 3.4 0.56 3.8 0.70 2.2 0.29 2.5 0.32 2.9 0.8 12.9 4.3 5.44 42.6 0.12 0.27 1.2 20 1.4 3.3 0.3 1.4 0.2 0.04 0.3 0.06 0.3 0.07 0.2 0.04 0.2 0.04 0.2 0.1 1.0 0.7 0.60 6.4 0.01 0.03

4.1 37.1 18.0 40.8 3.9 19.7 4.4 0.22 4.3 0.72 5.3 0.93 3.3 0.41 3.6 0.47 5.3 1.6 15.2 4.7 0.22 5.3 0.14 0.16 0.2 3.5 2.0 3.2 0.4 2.2 0.6 0.04 0.7 0.10 0.7 0.12 0.5 0.06 0.5 0.06 0.7 0.1 1.9 0.4 0.02 0.1 0.01 0.00 8.4 46.0 26.6 63.7 6.4 23.7 5.3 0.29 4.8 0.92 5.9 1.26 3.7 0.59 4.4 0.63 6.3 2.8 21.3 8.7 0.21 4.0 0.14 0.19 0.5 9.2 3.9 4.2 0.3 2.7 0.4 0.02 0.4 0.07 0.4 0.08 0.2 0.04 0.3 0.06 0.7 1.7 2.4 0.6 0.05 0.6 0.02 0.01

The Süphan Dag obsidian forms a homogeneous chemical group that has zirconium and barium contents similar to those of the Hatis and Sarikamis 2 obsidian (Fig. 2), but has a far higher Ba/Sr ratio (Fig. 4).

CONCLUSION Twenty-two different chemical groups are thus defined from our geological corpus (as previously mentioned in Table 1): seven for eastern Turkey (if we consider that the Akhurian River secondary deposit is not truly an Armenian source, but has a Turkish origin), 14 for Armenian obsidian and one for Georgian obsidian. Two different compositional groups are obtained for both the Tsaghkunyats and the Hatis volcanoes, while three different groups are defined for Arteni and Syunik. For eastern Turkey, at least four different compositional groups originate from the surroundings of Sarikamis. Average compositions and standard deviations obtained for the different groups are given in Table 4. This study of obsidian sources in the southern Caucasus and eastern Turkey shows that the data are still fragmentary, and that new geological surveys on certain deposits are necessary (especially on the sources of Arteni in Armenia and of Sarikamis and Yaglica Dag in the province of Kars in Turkey). Knowledge of the locations and of the characteristics of the different eruptive episodes is essential in order to obtain an exhaustive and reliable geological database, enabling thereby precise determination of the origins of the artefacts. The analytical results confirm that visual examination cannot enable a discrimination of the numerous obsidian sources in this region. Indeed, the different varieties (texture and colour) belonging to the Gutansar complex form a homogeneous chemical group, whereas the same varieties found on various obsidian sources belong to different chemical groups. If we refer to the barium and zirconium contents, obsidians in this large territory split into four main groups, which show, in Armenia, an increase in the barium content from the south-east (Syunik) to the north-west (Ashotsk). Thus the following groups can be distinguished: • a group with low contents (<100 ppm) in barium and zirconium—Syunik, Gegham, Khorapor and part of Arteni; • a group with low barium contents (<100 ppm) and middle to high zirconium contents (125–300 ppm)—Tendürek, Meydan Dag and Sarikamis North (secondary deposits of the Akhurian River); • a group with middle to high barium contents (175–700 ppm) and low to middle zirconium contents (50–150 ppm)—Gutansar, Hatis, Chikiani, Sarikamis South, Tsaghkunyats 1 (Damlik, Ttvakar) and part of Arteni; and • a group with high barium contents (>700 ppm) and mid-ranging zirconium contents (100–200 ppm)—Ashotsk and Tsaghkunyats 2 (Kamakar, Aïkasar). In most of the sources, a ‘continuum’ of the barium contents (and often the zirconium contents) is observed, either within the same chemical group (Chikiani, Gutansar) or between the various chemical groups of the same magmatic chamber (Syunik, Arteni). The method used to differentiate the compositional groups of obsidians is based on simple binary diagrams, which combine contents (Zr–Ba) and ratios (Nb/Zr, Y/Zr, Ba/Zr and Ba/Sr). This method enables quick discrimination between the obsidian sources exploited by the inhabitants of the archaeological sites studied. However, when these elements do not allow the distinction between sources of very close compositions, as is the case for Syunik, Khorapor and Gegham, the large number of elements determined by LA–ICP–MS always allows us to find other element couples that give a clear separation of these outcrops.

ACKNOWLEDGEMENTS The authors express their gratitude to the French Ministry of Foreign and European Affairs and the Academy of Science of Armenia, which provided ﬁnancial backing for their work in Armenia. They are sincerely grateful to Marie-Claire Cauvin (CNRS, Lyon), Catherine Kuzucuoglu (CNRS, Meudon), Catherine Marro (CNRS, Lyon) and Michael Glascock (University of Mis- souri Research Reactor Center) for providing geological samples of obsidian.

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