STAR: SCIENCE & TECHNOLOGY OF ARCHAEOLOGICAL RESEARCH, 2018 https://doi.org/10.1080/20548923.2017.1417781 Geo-material provenance and technological properties investigation in Copper Age menhirs production at Allai (central-western Sardinia, Italy) Marco Serra a,b,c, Valentina Mameli c,d and Carla Cannas c,d aLASP – Laboratorio di Antichità Sarde e Paletnologia, Dipartimento di Storia, Beni Culturali e Territorio, Università di Cagliari, Piazza Arsenale 1, 09100 Cagliari, Italy; bAUSI – Consorzio per la Promozione delle Attività Universitarie del Sulcis-Iglesiente; C.R.E.A.TE.– Centro di Ricerca per l’Energia, l’Ambiente e il Territorio, Palazzo Bellavista-Monteponi, 09016 Iglesias, Italy; cINSTM, Cagliari Unit; dDipartimento di Scienze Chimiche e Geologiche, Università di Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy ABSTRACT KEYWORDS During the 2nd millennium BC anthropomorphic menhirs belonging to a 3rd millennium BC Sardinia; Copper Age; sanctuary were reused as building material in the Arasseda Nuraghe (Sardinia, Italy). To menhir; provenance study; analyse the Arasseda menhirs and the local Monte Ironi geological samples (presenting technological properties similar visual features), chemical (pXRF, ICP-OES, ICP-MS), mineralogical-chemical (PXRD) and physical (Mohs hardness) measurements were performed. Through the experimental data, the menhirs source provenance and the technological properties (workability, durability) of the raw material chosen for sculptural purposes during Copper Age were investigated. To the authors’ knowledge this is the first archaeometric study on the Arasseda menhirs (the third on Sardinian menhirs) and one between the few recently developed on European megaliths. nd Introduction Bronze Age (2 millennium BC). These artefacts show an ogival frontal profile, a plano-convex section Megalithism appeared in Europe during the 6th millen- and are characterised by geometric representations nium BC, soon erecting a number of archaeological (generally interpreted as human anatomical parts) evidence related to cults of death and ancestors. made by the bas-relief technique (Atzeni 1992; Cossu Among the megalithic monuments it is worth men- 1996; Cicilloni 2008)(Figure 2). tioning menhirs, that are present in many geographical An ancient quarry of ignimbrite blocks (Figure 3A) contexts between Spain and Ural mountains. The pro- was discovered near the nuraghe and the sculptures’ cess of standing stones’ spread across the Central-Wes- find area (Cossu 1996). The recent finding of Monte tern part of Europe and their artistic and symbolic Claro culture polished pottery (cfr. Basoli, Doro, and evolution between 6th and 3rd millennia BC, is still Zedda 2012) during a survey performed in the quarry not clear. However, today a good part of the archaeol- site (Figure 3B), suggested the probable use of the ogists endorses the polygenic origin of the phenom- stone blocks in Eneolithic times (2900–2300 cal BC enon (Guilaine 1980; 2004), rejecting the traditional according to Melis 2009), perhaps for the production diffusionist and migrationist theses (Arnal, Arnal, of the Arasseda menhirs. and Demurtas 1983). So far, few studies investigated the source prove- As in other regions of Europe (Taçon 1999; Calado nance and the technological properties of European 2002) Sardinian menhirs were probably realised for the megaliths (Bevins, and Ixer 2013; Bevins, Ixer, and cult of death (Perra 1992; Cossu 1996) or used as terri- Pearce 2014; Thorpe et al. 1991; Pirson, Toussaint, torial markers (Atzeni 1982; Saba 2000; Usai and Perra and Frèbutte 2002, 2003; Williams-Thorpe et al. 2012). Today, over 100 anthropomorphic menhirs 2006) and a small part of them concerns menhirs. (made of a wide variety of sedimentary, metamorphic Only two of the available research works addressed Ita- and volcanic stones) are known in Sardinia, specifically lian standing stones characterised by anthropomorphic for the areas called Nurra, Marghine, Mandrolisai, Bar- features (Di Battistini, Franzini, and Lezzerini 2008; bagia di Belvì, Barigadu, Marmilla, Sarcidano and Sul- Rubinetto et al. 2014) similar to those of Eneolithic Sar- cis (Cicilloni 2008, 2013)(Figure 1). dinia, probably produced from the first centuries of 3rd In the 1990s some Eneolithic menhirs were found in millennium BC (Melis 2009; Cocchi Genick 2012; Arasseda, near the small town of Allai (Barigadu zone, Perra 2012). central-western Sardinia) (Figure 1). They were reused During the last decades, some assumptions on stone to build the Arasseda Nuraghe during the Sardinian working technology and provenance of geo-resources CONTACT Marco Serra [email protected] © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 2 M. SERRA ET AL. Figure 1. The island of Sardinia in the Central European geographic framework (A); generalised map of Sardinia showing the men- hir find localities (B); territory of Allai showing the Arasseda hill with nuraghe, menhirs and quarry site locations (C). employed in Neolithic and Eneolithic Sardinian mega- failure to sistematically adopt a synergy between the lithism were formulated (Atzeni 1982; Maoddi 1995; traditional archaeological investigation and archeome- Castaldi, 2000; Marini et al. 2007; Murru et al. 2008). try. The application of this joint approach to the study However, the research on this item, especially with of prehistoric Sardinian standing stones is currently reference to menhirs, has always been rare due to the restricted to two cases, performed on the menhirs of Figure 2. Menhirs from Allai: Arasseda II (1), Arasseda III (2) and Arasseda VII (3). STAR: SCIENCE & TECHNOLOGY OF ARCHAEOLOGICAL RESEARCH 3 Figure 3. A) Arasseda quarry site: layout plan and cross sections; B) Eneolithic (Monte Claro culture) ceramic shards from the Ara- sseda quarry site. Sarcidano (Figure 1), specifically of Nurallao (Serra, menhirs recently removed from Arasseda Nuraghe Mameli, and Cannas 2016a) and Laconi (Serra, and displayed in the Sardinian archaeological museum Mameli, and Cannas 2016b). of Laconi. In continuity with the European tradition of In the frame of the few archaeometric examinations archaeometric studies on megaliths, the selected of the Eneolithic Sardinian standing stones, the authors approach (visual inspection and chemical analysis) present the results of a study concerning the three aims to detect the source provenance of the raw 4 M. SERRA ET AL. materials employed for the production of the Arasseda 2000; Piccioli 1998; Potts et al. 2006; Ruge, Barber, and menhirs. In addition, through the definition of miner- Magee 2007), including samples from the unmodified alogy and hardness of the stone, the research investi- bedrock (MIA_C1-6) and from the quarry site of Ara- gates the workability and durability of the geo- sseda (MIA_C7-8) (Figure 5). The topographic pos- resource employed in the Arasseda menhirs’ ition of each sample was recorded by means of a GPS manufacture. system (Fornaseri, Malpieri, and Tolomeo 1975) and shown in the map of Figure 4. The archaeometric study was performed on the Materials and methods three Arasseda Eneolithic menhirs hosted in the “ ” Geological setting Museo della Statuaria Preistorica in Sardegna of Laconi (Figure 2). The discoverers labelled these men- In the Barigadu region, on the paleozoic metamorphic hirs as Arasseda II, III and VII respectively (Atzeni basement, the appearance of rhyolitic lava domes and 1992; Cossu 1996). flows took place during the Cenozoic Era (Figure 4). In the northern part of Allai the small ignimbritic out- crop of Monte Ironi (produced by a dacitic glowing cloud developed during the Oligo-Miocene period) Analyses on the geological samples closed the volcanic stratigraphy (Figure 5A). This pyr- The visual inspection of the geological samples was oclastic outcrop, composed of idiochromatic rocks performed by naked eye and 2.5X magnifying lens always reddish-brown in colour because of the oxi- (Hermes and Ritchie 1997b; Ricq de Bouard 2002; Gar- dation of iron in the contained iron-minerals (Assorgia rison 2003) and allowed to describe their macroscopic et al. 1995, 1998), forms the Arasseda hill, today sur- features. rounded by a wide quaternary alluvial soil deposit All the eight intact samples were first analysed with (Figure 4). a portable X-Ray Fluorescence spectrophotometer (pXRF) to determine (qualitatively and semi-quantitat- ively) their elemental composition. The pXRF analyses Sampling were carried out through an ASSING LITHOS 3000 The strong layering of paleozoic shales and cenozoic spectrophotometer. The experimental conditions rhyolites, rules out their use to make megaliths as men- were defined as follows: acquisition time = 600 s; vol- hirs. Conversely, the Monte Ironi ignimbrites show a tage = 25 kV; electric current = 150 μÅ; collimator structure without close cleavage planes (Argiolas diameter of the incident X-rays beam = 5 mm; distance et al. 2006) that certainly could allow the production between the source and the sample = 10 mm. On each of megalithic sculptural works. In addition, among sample, the analysis was performed on three different the geo-resources present in Allai, the Monte Ironi vol- areas of the fresh rock core, detectable