Article
Reference
Raw material choices and material characterization of the 3rd and 2nd millennium BC pottery from the Petit‐Chasseur necropolis:
Insights into the megalith‐erecting society of the Upper Rhône Valley, Switzerland
CARLONI, Délia, et al.
Abstract
Owing to its well‐preserved and long‐lasting archaeological record, the necropolis of Petit‐Chasseur in the Upper Rhône Valley (3100–1600 BC) showcases the economic, social, and ideological changes of 3rd and 2nd millennium BC Europe excellently. An in‐depth investigation of pottery artifacts was carried out using multiple spectroscopic and microscopic techniques. Nine types of ceramic fabrics were identified based on the variety of temper and natural inclusions; however, the mineralogy and phase chemistry of the ceramic matrix showed the paste to be primarily illitic or muscovitic, irrespective of the inclusion type.
Muscovitic clays were likely procured from the fluvioglacial, glaciolacustrine, colluvial, and till sediment abundantly available at higher altitudes of the Upper Rhône Valley, whereas illitic clays were acquired from pedogenized loess horizons or the Rhône River alluvium. Different raw material choices and paste preparation practices suggest distinct ceramic traditions that likely existed in the valley during the 3rd and 2nd millennia BC. This, along with the hypothesized provenance of the raw [...]
CARLONI, Délia, et al . Raw material choices and material characterization of the 3rd and 2nd millennium BC pottery from the Petit‐Chasseur necropolis: Insights into the megalith‐erecting society of the Upper Rhône Valley, Switzerland. Geoarchaeology , 2021
DOI : 10.1002/gea.21867
Available at:
http://archive-ouverte.unige.ch/unige:151864
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Geoarchaeology. 2021;1–36. wileyonlinelibrary.com/journal/gea
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1R E S E A R C H A R T I C L E
Raw material choices and material characterization of the 3 rd and 2 nd millennium BC pottery from the Petit ‐ Chasseur necropolis: Insights into the megalith ‐ erecting society of the Upper Rhône Valley, Switzerland
Delia Carloni
1| Branimir Š egvi ć
2| Mario Sartori
3| Giovanni Zanoni
2| Andrea Moscariello
3| Marie Besse
11Laboratory of Prehistoric Archaeology and Anthropology, Department F.‐A. Forel for Environmental and Aquatic Sciences, University of Geneva, Geneva, Switzerland
2Department of Geosciences, Texas Tech University, Lubbock, Texas, USA
3Department of Earth Sciences, University of Geneva, Geneva, Switzerland
Correspondence
Delia Carloni, Laboratory of Prehistoric Archaeology and Anthropology, Department F.‐A. Forel for Environmental and Aquatic Sciences, University of Geneva, 66 boulevard Carl Vogt, Geneva 1211, Switzerland.
Email:delia.carloni@unige.ch
Scientific editing by Kevin Walsh.
Funding information Fonds national suisse (FNS),
Grant/Award Number: 172742; Société de Physique et d'Histoire Naturelle de Genève (SPHN)‐Augustin Lombard Grant, PI D.
Carloni
Abstract
Owing to its well‐preserved and long‐lasting archaeological record, the ne- cropolis of Petit‐Chasseur in the Upper Rhône Valley (3100–1600 BC) show- cases the economic, social, and ideological changes of 3rd and 2ndmillennium BC Europe excellently. An in‐depth investigation of pottery artifacts was car- ried out using multiple spectroscopic and microscopic techniques. Nine types of ceramic fabrics were identified based on the variety of temper and natural inclusions; however, the mineralogy and phase chemistry of the ceramic matrix showed the paste to be primarily illitic or muscovitic, irrespective of the inclusion type. Muscovitic clays were likely procured from the fluvioglacial, glaciolacustrine, colluvial, and till sediment abundantly available at higher altitudes of the Upper Rhône Valley, whereas illitic clays were acquired from pedogenized loess horizons or the Rhône River alluvium. Different raw material choices and paste preparation practices suggest distinct ceramic traditions that likely existed in the valley during the 3rd and 2nd millennia BC. This, along with the hypothesized provenance of the raw material, is likely in favor of various prehistoric communities gathering at the megalithic necropolis from close and distant parts of the valley using the Petit‐Chasseur site as a place of assembly.
K E Y W O R D S
Bell Beaker, Early Bronze Age, Final Neolithic, Petit‐Chasseur, pottery archaeometric analysis
This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
© 2021 The Authors.Geoarchaeologypublished by Wiley Periodicals LLC.
1 | I N T R O D U C T I O N
The 3rd and 2nd millennia BC in Europe were marked by great economic, social, and ideological changes (Greenfield,2010; Guilaine, 2007; Harrison & Heyd,2007; Kienlin & Roberts,2009; Pétrequin et al.,2006; Radivojevićet al.,2010; Sherratt,1983). The innovations in technology and subsistence economy were related to the in- creasing social complexity and the appearance of the hierarchically differentiated mortuary patterns (Pétrequin et al.,2006; Sherratt, 1983). Within the latter, the funerary megalithic monuments are one of the most compelling expressions (Joussaume, 1988; Schulz Paulsson,2017). Megalithic cemeteries reflect a surplus in the pro- duction, social inequality, and rise of political competition as well as represent the key contexts for the investigation of prehistoric social organization (Gallay, 2006; Schulz Paulsson, 2017; Steimer‐ Herbet,2004; Testart,2005).
Taking into account the long history of use (3100–1600 BC) of the Petit‐Chasseur megalithic cemetery1(Sion, Switzerland; Figure1) and its iconographic apparatus and significance for ancient societies, this site has been recognized as an extraordinary source of evidence for documentation and analysis of 3rdand 2ndmillennia BC economic, social, and ideological changes in Europe (Besse, 2014;
Gallay,1995a,2014; Harrison & Heyd,2007). The site's history was marked by recurrent episodes of megalithic monument erection and desecration, which previous research considered to be related to social consecration and desecration (Corboud & Curdy, 2009;
Gallay,1995a,2007,2014, 2016). On the basis of anthropological data, two inferences were drawn: (1) the occurrence of selective fu- nerary recruitment and (2) the potential existence of family ties among individuals buried in the same grave (Desideri & Eades,2004;
Perréard Lopreno,2014). For these reasons, the megalithic society of the Upper Rhône Valley is characterized by inequality and social competition, which was expressed and challenged via an ostentatious display of wealth at the Petit‐Chasseur necropolis (Gallay, 1995a,2007,2014,2016; Testart,2005,2014).
Ceramic containers are common at the Petit‐Chasseur site.
These artifacts either accompanied the dead as grave goods during the Final Neolithic (FN) (3100–2450 BC) and Bell Beaker (BB) (2450–2200 BC) periods or were deposited as offerings during ritual practices throughout the Early Bronze Age (EBA) (2200–1600 BC) (Bocksberger,1976,1978; Gallay,1989; Gallay & Chaix,1984). The typology of the pottery, as well as the fabrication and decorating techniques employed, clearly differs from one period to another, highlighting the existence of cultural discontinuities in the material culture of the Upper Rhône Valley (Besse et al., 2011; Derenne et al., 2020; Harrison & Heyd,2007). Ceramic findings from the Petit‐Chasseur necropolis, therefore, provide valuable information
concerning the history of the site and the social context of pre- historic communities from the region. This was further explored by undertaking a series of archaeometric pottery analyses, which has never been done for ceramics from this site and Upper Rhône Valley prehistoric pottery in general. The aim of the present paper is thus to characterize the ceramic grave goods and offerings recovered at the Petit‐Chasseur necropolis via an assessment of their petrography, mineralogy, and chemistry in the context of the raw material choices and regional geology. In other words, this paper discusses the com- position of ceramics with respect to (1) the literature data, (2) the Upper Rhône Valley geology, (3) the funerary monument from which it was recovered, and (4) the sequence of events that took place in the cemetery during its long history of occupation and frequentation.
Cultural discontinuities expressed by the material culture changes over time (Besse et al.,2011) are further discussed by unveiling the raw material choices and exploitation practices. This is particularly interesting with respect to the BB culture's appearance in the second half of the 3rdmillennium BC (Besse et al.,2011). Some alterations in the raw material selection and exploitation practices might also have occurred during the six centuries of the EBA. Generally, the shifts within technical traditions are expressions of the history of social groups and variations in ceramic production modalities, which allows for insights into the underlying historical dynamics (Roux,2011,2019; Shennan,2013).
The inferences drawn from the raw material use can be utilized to reconstruct the manufacturing traditions, the patterns of dis- tribution, and the circulation of containers from a synchronic and a diachronic point of view (Roux, 2019, and references therein).
However, one must bear in mind that final users were not necessarily also the manufacturers (Roux,2019; Schiffer,2001). Due to the fact that prehistoric pottery is dominated by natural or/and intentionally added coarse inclusions (e.g., Muntoni & Laviano, 2008; Tanasi et al.,2019), this investigation focused on mineral and rock inclusions as well as the clay paste. Such an approach was essential in the context of Alpine geology, which is devoid of any significant clay accumulations due to intensive tectonics and relatively low rates of chemical weathering and clay mineral formation (Mavris et al.,2011;
Reynolds,1971).
2 | A R C H A E O L O G I C A L B A C K G R O U N D
The earliest phase of the Petit‐Chasseur necropolis (Figure1) dates to the FN (3100–2450 BC) and is represented by seven anthro- pomorphic stelae and two dolmens with a triangular base that host collective burials (MXII and MVI). The FN stelae depict anthro- pomorphic elements, daggers, and double spiral pendants (style A) (Corboud & Curdy,2009). The dolmen MXII was found without most of the lithic slabs used to build the burial chamber. This is consis- tent with reports of monument plundering during the FN (3100–2450 BC) and/or BB period (2450–2200 BC) (Favre &
Mottet,2011). However, the comparatively younger monument MVI (constructed at ca. 2900 BC) was built using two reused stelae of
1DMS geographical coordinates of Petit‐Chasseur archaeological site: sector I‐II
46°13ʹ49.00988″N, 7°20ʹ48.71855″E; dolmen MXII 46°13ʹ53.06266″N, 7°20ʹ54.77823″E.
These coordinates were obtained by converting the Swiss projection coordinates published by Baudais et al. (1989) into the global WGS84 coordinates (GPS) using the NAVREF converter provided by the Federal Office of Topography of Switzerland.
type A (Bocksberger, 1976; Corboud & Curdy, 2009). The grave goods found in FN tombs comprised ornamental pendants and beads, flint artifacts—including objects made of Grand‐Pressigny flint—and pots (Affolter,2014; Bocksberger,1976; Favre & Mottet,2011).
The use of the area as a burial site continued into the BB period, with three main events having taken place. First was the construction of three dolmens without a triangular base (MI, MV, and MXI) made from regular lithic slabs and anthropomorphic stelae of types A and B (Bocksberger, 1978; Corboud & Curdy, 2009; Gallay,1989; Gallay &
Chaix, 1984). The new type B engraved stelae depict clothing with complex geometric patterns, bows and arrows, and solar symbols (Corboud & Curdy,2009). Second, the FN dolmen MVI was emptied and reused (Bocksberger,1976). Third, a new type of tomb, denominated
“cists”(MII, MIII, MVII, MVIII, MIX, MX, and MXIII), made an appearance at the site. These lacked an entrance and were built using regular lithic slabs and re‐employed type B stelae (Bocksberger, 1978; Corboud &
Curdy,2009; Gallay,1989; Gallay & Chaix,1984). Furthermore, during the BB period, the dolmens MV and MXI were emptied at an unspecified moment and their funerary deposits were displaced outside the burial chamber (Gallay,1989; Gallay & Chaix,1984). The transition from the FN to BB period is clearly visible in the material culture, especially in the pottery typology and the new type of anthropomorphic stelae (Besse et al.,2011).
The pits found in front of many FN and BB megalithic monu- ments suggest that engraved stelae were previously placed in front of the tombs (Bocksberger,1976,1978; Corboud & Curdy, 2009;
Gallay,1989; Gallay & Chaix,1984). This hypothesis is supported by the recovery of a stela that was placed ahead of the dolmen MV (Corboud & Curdy,2009; Gallay,1989) (Figure1). Anthropomorphic stelae in the necropolis have been interpreted as a sign of the social consecration of important figures (Gallay,1995a). Such individuals probably had strong political and economic power and were considered worthy of glorification (Corboud & Curdy, 2009;
Gallay,1995a). However, destruction and reuse of stelae as building
material, that is, the desecration of these anthropomorphic representations, suggest that these figures might have lost their authority and prestige (Gallay,1995a). In addition, the plundering of collective graves marks political instability within the megalith‐ erecting society of Petit‐Chasseur (Corboud & Curdy, 2009;
Gallay,1995a,2007,2014,2016).
The last period of site use is the EBA (2200–1600 BC), when the frequentation of the cemetery began to have ritualistic traits (Bocksberger,1976,1978; Gallay,1989; Gallay & Chaix, 1984).
Whereas the site was primarily exploited for funerary purposes during the FN and BB periods, the EBA saw the worship of megalithic monuments as objects of ancestor cult(s) (Gallay, 1995a; Gallay & Chaix,1984). The cultic activities con- sisted of the ritual depositions of jars and the constructions of cairns. The megalithic cemetery of Petit‐Chasseur is a unique prehistoric archaeological site with evidence of long‐term occu- pation in the Upper Rhône Valley. The span of the known pre- historic settlements in the region lasted for two to three centuries at most, whereas the frequentation of the necropolis lasted more than one thousand years (Baudais, 1995; Baudais et al., 1989;
Baudais & Honegger, 1995; Besse, 2012; Besse et al., 2011;
Carloni et al., 2020; David‐Elbiali, 1990; Giozza et al., 2005;
Honegger, 1995, 2011; Mariéthoz, 2005; Meyer et al., 2012;
Mottet et al., 2011; Mottet & Giozza,2011). The significant in- vestment in iconography suggests a society characterized by in- equalities, social competition, and ostentatious displays of wealth (Corboud & Curdy, 2009; Gallay, 1995a, 2007, 2014, 2016).
However, recurrent episodes of monument erections and dese- crations indicate a time of instability, both socially and politically (Corboud & Curdy,2009; Gallay,1995a; Testart,2014). With its funerary, political, and ceremonial function, Petit‐Chasseur stands as a key site for investigating prehistoric communities' social or- ganization during the 3rd and 2nd millennia BC (Besse, 2014;
Gallay,1995a,2011,2014; Harrison & Heyd,2007).
F I G U R E 1 Location of the Petit‐Chasseur site (red rhombus) in Switzerland (a) (modified after Swiss Federal Office of Topography, 2007) and plan of the necropolis (b) (Corboud & Curdy,2009, p. 20). The Final Neolithic dolmens MVI and MXII are clearly recognizable for their triangular base. The majority of the monuments were built by reusing engraved stelae, whose presence is marked by a dark gray color (e.g., MI built with four stelae, MIX with just one stela) [Color figure can be viewed atwileyonlinelibrary.com]
3 | G E O L O G I C A L B A C K G R O U N D
The present‐day geology of the Upper Rhône Valley area results from the collision of the European continental margin and the Adria microplate during Paleogene to Neogene Alpine orogenesis (e.g., Handy et al.,2010; Schmid et al.,1996,2004). Three main groups of tectonic units, each belonging to paleogeographic domains with distinct geological histories, are identifiable (Figure 2a) (Stampfli,2001). The uppermost units, forming summits along the left bank of the Rhône River, belong to the Dent Blanche Complex (Manzotti et al., 2014; Schmid et al., 2004). These units largely consist of intrusive felsic rocks and derived gneiss from the Aus- troalpine margin (Figure2b). The underlying Penninic realm is di- vided into three units affected by the greenschist Alpine metamorphism (Stampfli et al.,1998). The highest is made of ser- pentine, metagabbro, metabasalt, radiolarian chert, and calcareous metaflysch. These ophiolitic and metasedimentary rocks (Figure2a,b) are related to the Piedmont–Liguria oceanic domain. The middle one is comprised of gneiss, mica schist, quartzite, and marble from the Briançonnais microplate and the lower unit of calcareous metaflysch from the Valaisan domain (Stampfli et al.,1998). On the right bank of the Rhône River, the Helvetic units are found in a stack of nappes composed of sedimentary and very/low‐grade metamorphic rocks (e.g., limestone, sandstone, evaporites, shale, schist, marble;
Figure2a,b). They overlay the External Crystalline Massifs, which are located at both ends of the Upper Rhône Valley (Figure 2a) and represent a pre‐Alpine European crust uplifted and exhumed during the Alpine orogeny (Hettmann et al., 2009; von Tscharner et al.,2016). The high‐grade metamorphic rocks of the Early Neo- proterozoic and Low Paleozoic age are associated with the Variscan granitoids and frame some narrow grabens with Permo‐ Carboniferous filling. The main lithologies are gneiss, amphibolite, granite, granodiorite, rhyolite, schist, and sandstone (Figure2b) (e.g., Hettmann et al.,2009; von Raumer & Bussy,2004). The granite of the Mont Blanc External Massif was overprinted by the greenschist
Alpine metamorphism (von Raumer & Bussy, 2004), whereas in- trusive rocks of the Aar External Massif are being cataclasized especially in the southern contact zone (Hettmann et al.,2009).
Geological events related to Quaternary glaciation in the Alps largely shaped the actual geomorphology of the Upper Rhône Valley (Ivy‐Ochs et al., 2008, 2015; Valla et al., 2011, and references therein). The Rhône River originates at the homonymous glacier in the far east of the valley and drains into Lake Geneva. At present, there are more than 50 tributary inflows between the Rhône glacier and Lake Geneva. They continuously discharge sediment into the Rhône River, contributing in various proportions to the total watershed (Stutenbecker et al.,2016,2018).
Large amounts of metamorphic rock and semi‐arid climatic conditions hampered a large‐scale formation of clay deposits, which could later have been procured as a raw material in pottery manu- facturing. However, local clay enrichments through clay mineral neoformation is possible and it is related to the peculiar alteration environments that gave rise to loess formation (Stalder, 2015).
Therefore, prospective clay sources in the area are largely related to alluvial deposits of the Rhône and its main tributaries, torrential deposits of the slopes, glaciolacustrine deposits, and lacustrine deposits. Contrasting lithologies of various geological units must have strongly influenced the derived soil compositions. In the alluvial sediment of the Rhône banks, these distinct mineralogical and geo- chemical fingerprints may be obliterated through the cycles of sediment mixing (Figure2).
4 | M A T E R I A L S A N D M E T H O D S 4.1 | Materials
The archaeological material recovered at the Petit‐Chasseur site is kept at the Musée d'Histoire du Valais in Sion (Valais, Switzerland).
Detailed information on the material was published for each funerary F I G U R E 2 Geotectonic (a) and lithological (b) maps of the Upper Rhône Valley. Modified after the data provided by the Swiss Federal Office of Topography (https://map.geo.admin.ch/) [Color figure can be viewed atwileyonlinelibrary.com]
monument (Bocksberger, 1976, 1978; Favre & Mottet, 2011;
Gallay,1989; Gallay & Chaix,1984); however, heretofore, no ana- lyses targeting the entire ceramic assemblage became available.
Therefore, we have carried out a thorough screening of the material, which included a detailed observation of each potsherd and collec- tion of quantitative (i.e., number of potsherds/fragmented pots and weight) and qualitative data (i.e., chronology, recovering context, and part of the vessel represented). The acquired information was stored in a database (Supporting Information MaterialS1), thus permitting examination of the ceramic assemblage in its entirety from a vertical (stratigraphic layer, chronology) and a horizontal (spatial) point of view. The assemblage accounts for 61 fragmented pots and 3181 potsherds (i.e., rims, handles, bases, and body fragments) (Table1).
The quality and quantity of recovered ceramic material vary con- siderably among funerary monuments (Table 1). EBA pottery has been found around megalithic monuments in great numbers, which testifies to the importance of cultic activities. For this reason, most of the recovered ceramic assemblage consist of EBA pottery (Table1).
However, this was not the case for all of the megalithic monuments.
Some of the tombs show no signs of EBA cultic activity—that is, ritual
depositions of jars and erection of cairn structures—and, conse- quently, were found devoid of EBA pottery. Some of these monu- ments were most likely buried at the turn of the 2nd millennium BC and, therefore, not accessible, which may explain a lack of EBA artifacts for certain dolmens (Bocksberger, 1976, 1978; Favre &
Mottet,2011; Gallay,1989; Gallay & Chaix,1984).
The sampling strategy was based on ceramic chronology, loca- tion, shape, and ceramic's macroscopic fabric. Despite some restric- tions imposed by the Museum, it was possible to obtain a comprehensive set of 80 samples, which covered most of the monuments, time periods, and macroscopic fabrics (Supporting In- formation MaterialS2and Figure3). Only a few FN potsherds were recovered at the site exclusively related to the dolmen MVI (Table1).
The excavators considered many body fragments as parts of the same vessels, even if they were not refitting (Bocksberger,1976).
This was likely the case for Pots 1, 2, and 3 (Supporting Information MaterialS1andS2). Such an assumption is based on the stratigraphic context in which they were found as well as the strong similarities of surface features, sherd morphology and thickness, and macroscopic fabrics (Bocksberger, 1976). To further investigate the groupings
T A B L E 1 Chronology of pottery recovered in the distinct topographic units of the site and relative incidence on the assemblage
Megalithic monument
MI MII MIIi MV MVI MVII MVIII MiX MX MXI MXII MXIII Total percentage (%)
Final Neolithic Pots ‐ ‐ ‐ ‐ 3 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 30 1
Rims ‐ ‐ ‐ ‐ 4 ‐ ‐ ‐ ‐ ‐ ‐ ‐
Handles ‐ ‐ ‐ ‐ 1 ‐ ‐ ‐ ‐ ‐ ‐ ‐
Bases ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
Body fragments ‐ ‐ ‐ ‐ 22 ‐ ‐ ‐ ‐ ‐ ‐ ‐
Bell Beaker period Pots 7 ‐ 1 5 7 4 ‐ ‐ ‐ 4 ‐ ‐ 148 5
Rims 1 ‐ 1 6 3 ‐ ‐ ‐ ‐ 4 ‐ ‐
Handles 1 ‐ ‐ 2 ‐ 2 1 ‐ ‐ 3 ‐ ‐
Bases 1 ‐ ‐ 2 1 ‐ ‐ ‐ ‐ ‐ ‐ ‐
Body fragments 13 ‐ 8 20 8 16 ‐ ‐ 7 20 ‐ ‐
Early Bronze Age Pots 1 ‐ ‐ 1 1 ‐ ‐ ‐ ‐ 27 ‐ ‐ 2876 89
Rims ‐ ‐ ‐ 19 11 1 ‐ ‐ ‐ 121 ‐ ‐
Handles ‐ ‐ ‐ 1 1 1 ‐ ‐ ‐ 49 ‐ ‐
Bases ‐ ‐ ‐ 3 2 1 ‐ ‐ ‐ 26 ‐ ‐
Body fragments ‐ ‐ ‐ 188 298 5 ‐ ‐ ‐ 2119 ‐ ‐
N/D Pots ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ 188 6
Rims ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
Handles ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ 2 ‐ ‐
Bases ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
Body fragments ‐ ‐ ‐ 124 ‐ ‐ ‐ ‐ ‐ 62 ‐ ‐
Total no. for monument 24 0 10 371 362 30 1 0 7 2437 0 0 3242 100
Note: These data are extracted from the study of the whole ceramic assemblage the authors carried out on the pottery materials. The complete database of Petit‐Chasseur ceramic findings may be found in Supporting Information MaterialS1.
suggested by excavators, several potsherds initially attributed to one single vessel were analyzed (Supporting Information MaterialS2).
This choice makes sense, considering the large compositional het- erogeneity generally featuring the prehistoric ceramics (Prehistoric Ceramic Research Group,2011). The group of FN sherds labeled as Pot 1 belonged to a jar‐like closed shape (Figure 3, PC01‐PC02;
Supporting Information MaterialS1), whereas Pots 2 and 3 consisted only of body fragments (Supporting Information MaterialS1). Iso- lated rim fragments attest to the presence of straight‐profile bowls in the ceramic assemblage (Supporting Information Material S1).
Whereas this material has been studied intensively (e.g., Besse, et al.,2014; Gallay,1995a,2014; Harrison & Heyd,2007), the FN material culture of the Upper Rhône Valley is still less known (Baudais & Honegger,1995; Carloni et al.,2020). The straight‐profile bowls may be found in contemporary settlement sites (Carloni et al., 2020), whereas a closed shape form similar to the one re- covered at the Petit‐Chasseur site has so far never been documented elsewhere in the region.
The BB samples consist of bell‐shaped beakers and cups, deco- rated with cord impressions (All‐Over Corded style) or complex
impressed patterns (All‐Over Ornamented style) (Figure3) (Besse et al.,2011). Harrison and Heyd (2007) attempted to create a re- lative chronology and seriation by dividing the BB ceramic assem- blage of the Petit‐Chasseur necropolis into four phases: Early Beaker phase A1, Middle Beaker phase A2, Late Beaker phase B1, and Latest Beaker phase B2. However, Besse et al. (2011) disputed the presence of Early Beaker phase A1. The BB culture has been known for its diffusion over a vast geographic area across the European continent and North Africa (e.g., Besse, 2015; Lemercier, 2018; Olalde et al.,2018), and has been widely documented in Switzerland and North Italy from both the settlement and funerary sites (Besse,2014; Besse, Derenne, et al., 2019; Hafner & Suter,2003;
Hafner et al.,2014). In the Upper Rhône Valley, there are only two archaeological sites from where the unequivocal BB pottery has been recovered: the Petit‐Chasseur necropolis and Bitsch“Massaboden” (Besse, et al.,2014; Carloni et al.,2020; Meyer et al.,2012).
Lastly, the EBA jar fragments (rim diameter ~25 cm) were found inside the burial chamber and outside monuments (i.e., MXI int. vs.
MXI ext.). The stratigraphy, radiocarbon dating, and ceramic typology allowed for the classification of related material in four phases: I, II, F I G U R E 3 FiTypical pottery shapes of Petit‐ Chasseur samples (modified after
Bocksberger,1976; Gallay,1989; Gallay &
Chaix,1984): Final Neolithic closed shape (PC01, PC02), Bell Beaker all‐over corded (AOC) beaker (PC74), Bell Beaker all‐over ornamented (AOO) beaker (PC73, PC79), Bell Beaker cup (PC71), Early Bronze Age cordoned jars (PC48, PC49, and PC66)
III, and IV (Besse et al.,2011; Gallay & Chaix,1984). Cordoned jars similar to the ones recovered at the Petit‐Chasseur necropolis may be found in contemporary settlement sites spread across the Upper Rhône Valley, such as Naters“Altersheim,”Salgesch“Mörderstein,” Vex“Le Château,”Ayent“Le Château,”Sion“Petit‐Chasseur III,”and Rarogne “Heidnischbühl II” (Carloni et al., 2020, and references therein). Although the diffusion of cordoned jars over a vast area suggests a common stylistic tradition, this was not necessarily the case for other types of vessels (Carloni et al.,2020).
4.2 | Methods
The sample list with the applied analytical methods is provided in Supporting Information Material S2. Forty‐two samples re- presentative of the different macroscopic fabrics, pottery chronol- ogy, and megalithic monument have been the subject of an investigation by polarizing microscopy (OM) and automated electron microscopy (QEMSCAN®). These techniques provided insights into ceramic petrography and modal mineralogy along with microtextural and compositional characteristics of the clay matrix. The latter was further investigated by X‐ray diffractometry (XRD), applied on a selection of samples based on OM and QEMSCAN® results.
Scanning electron microscopy with energy‐dispersive spectrometry (SEM‐EDS) was then carried out on the selected samples deemed representative of different types of clay matrix as outlined by QEMSCAN® and XRD. Finally, the entire sample set—that is, 80 samples—has been studied geochemically by employing inductively coupled plasma mass spectrometry (ICP‐MS) or laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS).
4.2.1 | Polarization microscopy
Ceramic thin sections (42) were analyzed at the University of Geneva using a Leica Leitz DM‐RXP polarizing microscope (Supporting In- formation Material S2). The main features of ceramic paste (i.e., matrix, voids, and inclusions) were reported following the standard proposed by Whitbread (1989) and by Quinn (2013). Special atten- tion was paid to the rock and mineral inclusions, which were tested for their relative presence, size, degree of roundness, sphericity, and sorting. The nomenclature established by the Udden–Wentworth (U–W) grain‐size scale (revised by Terry & Goff,2014) was used for the size of aplastic inclusions. The recurrent association of certain phases and inclusions in ceramic paste allowed for the definition of several fabrics.
4.2.2 | XRD
XRD was performed on 17 powdered samples using a Bruker D8 Advanced diffractometer installed at the Department of Geosciences of Texas Tech University (Supporting Information Material S2).
The ceramic material was analyzed from 3 to 70° 2Θwith a step size of 0.02° and time of 1.8 s/step with a generator setup ofU= 45 kV andI= 40 mA. The diffraction patterns were analyzed by the Bruker EVA software suite and interpreted through comparisons with the PDF4 database, which was made available by the International Centre for Diffraction Data.
4.2.3 | Electron microbeam techniques
The entire thin‐section data set was analyzed using an FEI QEMS- CAN®Quanta 650F apparatus installed at the University of Geneva (Supporting Information MaterialS2). This enabled the inference of modal mineralogy and petrography on potsherds as well as the characterization of microtextures and the composition of the cera- mic clay matrix. The QEMSCAN® system is based on SEM‐EDS technology that is used to identify mineral phases by combining the backscattered electron brightness values, low‐count energy‐ dispersive X‐ray spectra, and the X‐ray count rate (Gottlieb et al.,2000). Spectra acquisition moves forward along predetermined fields and both the quantitative and qualitative data are easily re- trieved once the mineralogical map of the sample is produced. In pottery research, this technique has been applied only recently, de- livering high‐quality results as reported by several studies (Knappett et al.,2011; Šegvićet al., 2016). The QEMSCAN®measurements were performed at a high vacuum, acceleration voltage of 15 kV, and probe current of 10 nA on 42 carbon‐coated thin sections. X‐ray spectra acquisition time was 10 ms per pixel, using a point spacing of 5μm. The matrix's mineralogy and microtexture were studied in detail on a set of eight thin sections by means of SEM‐EDS in- vestigation (Supporting Information MaterialS2). The analyses were performed using a Zeiss Crossbeam 540 apparatus equipped with the EDS installed at the Microscopy Center of the College of Arts and Sciences of Texas Tech University. Data were obtained under a high vacuum, using the backscatter detector and acceleration voltage of 15 kV.
4.2.4 | Whole ‐ rock geochemistry
ICP‐MS geochemical analyses were performed on 70 samples at the Bureau Veritas Laboratories in Vancouver, Canada. Samples weigh- ing ~5–9 g were grounded and mixed with a lithium metaborate/
tetraborate flux, dissolved in nitric acid, and analyzed by ICP‐MS.
Samples were digested in aqua regia to detect the presence of rare and refractory elements. Loss on ignition was determined by mea- suring weight loss after ignition at 1000°C. Due to their light weights, the 10 BB samples were analyzed by LA‐ICP‐MS on fused discs at the Bureau Veritas Laboratories in Perth, Australia.
Repeated analyses of different sample aliquots indicated a relative SDof ±0.3% and ±0.5% for major and trace elements, respectively.
Raw elemental data may be found in Supporting Information Mate- rialS3. LA‐ICP‐MS and ICP‐MS data comparability was ensured by
analyses of samples PC23 and PC48 where two methods yielded differences that did not surpass 5%.
4.2.5 | Statistical treatment of geochemical data
Principal component analysis (PCA) was used to process raw geo- chemical data (STATISTICA 13 software package). Before PCA, a log10 transformation was applied to the original raw data to reduce the risk of misleading object classification by standardizing the available data set to intercomparable values (e.g., Hall, 2004;
Papachristodoulou et al., 2010). PCA reduces a multidimensional data set by inducing a smaller number of artificial variables called principal components (PCs) (e.g., Beier & Mommsen, 1994;
Papachristodoulou et al.,2010). The elemental concentration pattern of each sample is thus outlined in a plot constructed upon the first two PCs, which show the ceramics with similar composition in the form of agglomerated points (e.g., Mommsen, 2001; Šegvić et al., 2012). Finally, bulk chemical data were normalized to the North American Shale Composite (NASC) standards to investigate further element enrichments and deficiencies (Gromet et al.,1984).
As the pottery is manufactured using fractioned and mostly sedi- mentary material, that is, the clay‐rich sediments, the NASC normalization is considered a valuable tool for investigating ceramic geochemistry and the collection of data for provenance assessment (Braekmans et al.,2011).
5 | R E S U L T S
5.1 | Pottery petrography
The optical and QEMSCAN® analyses and documentation of the main features of ceramic paste (matrix, voids, and inclusion types) allowed a definition of nine ceramic fabrics (Table2, Figures4and5).
The main discriminator of ceramic assemblages was a large variety of rock inclusions. These inclusions were randomly oriented, and their type and mineralogy facilitated the correlation of analyzed potsherds with the regional Alpine lithology. Internal variability within each fabric, whenever relevant, was referred to as a“variant”(e.g., granite‐ rich pottery, var. 1, var. 2; see Table2).
5.1.1 | Fabric 1: Quartz and feldspar
This type of ceramic fabric is characteristic of one BB sample from monument MXI (Table 2). Its groundmass is homogeneous and moderately optically active with a brownish‐red color and a stri- atedb‐fabric. The particles of Fe oxide and/or siderite are found throughout the groundmass. Macro‐and meso‐vughs and planar voids are randomly oriented or parallel to the pot's walls. The system of horizontal voids may indicate a junction of juxtaposed parts as a forming technique. Aplastic inclusions range from
medium to very fine sand‐sized quartz, feldspar, and feldspar ag- gregates (Figures4aand5). Chert particles of the same size are also a common component of this fabric. All these inclusions are equant and elongated in shape, with angular to subangular edges.
Chert can also be subrounded. The grain size distribution is unimodal.
5.1.2 | Fabric 2: Granite
This fabric was observed in 1 BB and 13 EBA samples from monuments MV, MVI, MVII, and MXI (Table2). The fabric is marked by a heterogeneous matrix of slight to moderate optical activity (Figure 4b,c). The groundmass color ranges from yellowish‐ to reddish‐brown in all their gradations with only rare instances of black. A striated b‐fabric characterizes the groundmass of the sample PC75. This study also found particles of Fe oxide and/or siderite in the matrix and macro‐ and meso‐vughs (even mega), channel, and planar voids oriented either randomly or in a parallel configuration.
Both samples of variants 1 and 2 are characterized by the coarse silt to gravel‐sized (rarely pebble) inclusions derived from the granite–granodiorite–quartz diorite family (Table2). In gen- eral, the inclusions are poorly sorted, equant and elongated in shape, with angular to subangular edges (Figures4b,c and 5).
They may be tectonized and rich in vermiculitized biotite.
Plagioclase and K‐feldspar are occasionally found altered into the clay mineral assemblages. Samples of variant 1 also contain sand‐ sized rounded inclusions of fine‐grained granite with post- depositional calcite infills (Table2, Figures4band5). Fragments of sedimentary and low‐grade metamorphic rocks are rare and account for carbonate‐rich mudstone, Fe carbonate rich in Fe oxide, sandstone rich in volcanic rock fragments, schist, and cataclasite. The grain size distribution in this group is bimodal to trimodal.
5.1.3 | Fabric 3: Fine ‐ grained granite with Fe oxide
This group's samples belong to BB pottery with only one example documented in the EBA corpus (monuments MV, MVI, MVII, and MXI) (Table2). Ceramic groundmass of this fabric is largely hetero- geneous; its color is brown and/or yellowish‐ and reddish‐brown, while the matrix displays a slight to moderate degree of optical ac- tivity. The abundant Fe oxide and/or siderite particles are omnipre- sent in the matrix. Macro‐and meso‐vughs and/or elongated voids (channels, planar‐shaped) are present and either randomly oriented or parallel. The coarse silt to gravel‐sized inclusions of equant to elongate fine‐grained granite with Fe oxide, which have angular to subrounded edges, define this pottery fabric (Figures4d–fand 5, Table 2). Granite inclusions with similar morphometric character- istics are present as well. The grain size distribution observed in this fabric is bimodal to trimodal.
TABLE2Descriptionofthefabric Aplasticinclusions FabricMatrixVoids%Clast Dominant 50%–70%
Frequent–common 15–50%Few–rare0.5%–15%GSD
Max dimension (mm) 1QUARTZAND FELDSPAR No.1sample
BB:PC7985% Homogeneous,optically active,brownish‐red. Iron‐richparticles 5% Macro‐andmeso‐ vughsand planar, randomly orientedor parallel
10QuartzFeldspar,chertBiotite,micaU0.5 2GRANITE No.14samples
Var.1; EBA:PC11, PC12, PC20, PC23, PC25, PC34, PC35, PC38, PC47, PC69, PC70
73%–82% Heterogeneous,optically active,yellowish‐to reddish‐brownand black.Iron‐rich particles 3%–7% Mega‐,macro‐, andmeso‐ vughs, channelsand planarvoids, randomly orientedor parallel 13–20Biotite‐richgranite, granite
Fine‐grainedgranite withsecondary calcite
Quartz,feldspar,biotite,mica, sedimentaryrocks (carbonatemudstone,Fe‐ richcarbonaterock, sandstonewithvolcanic rockfragments),low‐grade metamorphicrocks(quartz schist,micaschist,chlorite schist)
BI,TRI4 Var.2; EBA:PC49, PC52; BB:PC75
70%–85% Heterogeneous,optically active,yellowish‐to reddish‐brownand black.Iron‐rich particles 5%–10% Mega‐,macro‐, andmeso‐ vughs, channelsand planarvoids, randomly orientedor parallel 10–20Biotite‐richgranite orgranite
Biotite,low‐grade metamorphicrocks (cataclasite,micaschist)
BI,TRI8; PC75:1 3FINE‐GRAINED GRANITERICH INFEOXIDE No.7samples
Var.1; BB:PC72, PC74, PC78
80%–85% Heterogeneous,optically active,yellowish‐and reddish‐brown. Abundantiron‐rich particles 5% Macro‐andmeso‐ vughsand channels, randomly oriented 10–15Fine‐grainedgranite withFeoxide
Biotite‐richgraniteor granite Quartz,feldspar,biotite,mica, sedimentaryrocks(micritic limestone),low‐grade metamorphicrocks(mica schist)
BI,TRI4 Var.2; BB:PC71, PC77,
75%–85% Heterogeneousand homogeneous, 5% Macro‐andmeso‐ vughs, 10–20Biotite‐richgraniteFine‐grainedgranite withFeoxide Quartz,feldspar,biotite,mica, sedimentaryrocks (carbonaterock,limestone,
BI,TRI4; PC21:4.5 (Continues)
TABLE2(Continued) Aplasticinclusions FabricMatrixVoids%Clast Dominant 50%–70%
Frequent–common 15–50%Few–rare0.5%–15%GSD
Max dimension (mm) PC80; EBA: PC21
opticallyactive, yellowish‐brownand brown.Abundantiron‐ richparticles channels,and planarvoids, randomly orientedor parallel
chert),low‐grade metamorphicrocks(mica schist,chloriteschist) 4Weatheredgranite No.2samples;EBA: PC56,PC57
70%–75% Heterogeneous,optically active,yellowish‐ brown.Iron‐rich particles 5%–10% Macro‐andmeso‐ vughsand planar, randomly orientedor parallel 20Weatheredgranite (secondary calcite)
Quartz,feldspar,biotite,mica, granite
TRI6.5 5Epidote‐richgranite No.1sample; BB:PC73
90% Homogeneous,optically active,brownish‐red. Veryabundantiron‐ richparticles 5% Meso‐vughs, randomly oriented 5Epidote‐richgraniteQuartzEpidote,feldspar,mica,Fe oxide
BI1 6Quartz–feldspar gneiss No.8samples
Var.1; EBA:PC40, PC48, PC66
75% Heterogeneous,optically active,brownor reddish‐brown.Iron‐ richparticles
5% Mega‐,macro‐, andmeso‐ vughsand channels,and planar, randomly orientedor parallel 10–20Quartz–feldspar gneiss
Fine‐grainedgranite withsecondary calcite Quartz,feldspar,biotite,mica, low‐grademetamorphic rocks(micaschist)
BI,TRI5 Var.2; EBA:PC39, PC54, PC59, PC62, PC63
73%–85% Heterogeneous,optically active,brownand reddish‐and/or yellowish‐brown.Iron‐ richparticles 3%–7% Mega‐,macro‐, andmeso‐ vughsand channels,and planar,mostly parallel 10–20Biotite‐richgraniteQuartz–feldspargneissQuartz,feldspar,biotite,mica, fine‐grainedgranitewith Feoxide,low‐grade metamorphicrocks(mica schist)
BI,TRI6 7Amphibolegneiss No.6samples
Var.1;78%–82% Heterogeneous,optically active,reddish‐brown 3%–7% Macro‐andmeso‐ vughsand 15AmphibolegneissQuartz,feldspar,amphibole, biotite,mica,sedimentary rocks(limestone),fine‐
BI,TRI5.4
TABLE2(Continued) Aplasticinclusions FabricMatrixVoids%Clast Dominant 50%–70%
Frequent–common 15–50%Few–rare0.5%–15%GSD
Max dimension (mm) EBA:PC16, PC17, PC32
orbrown.Iron‐rich particles planar, randomly orientedor parallel
grainedgranite,fine‐ grainedgranitewith secondarycalcite Var.2; EBA:PC30, PC31, PC33
75%–87% Heterogeneous,optically active,lightbrown, andreddish‐brown. Iron‐richparticles 3%–7% Mega‐,macro‐, andmeso‐ vughsand channels, mostly parallel 10–15Biotite‐richgraniteGneisswithamphibole,quartz, feldspar,biotite,mica, sedimentaryrocks (limestone),low‐grade metamorphicrocks(mica schist)
BI,TRI3.2 8Glaucophaneschist No.1sample FN:PC05
65% Homogeneous,black
5% Macro‐andmeso‐ vughsand planar, randomly oriented
30GlaucophaneschistEpidote,quartz,micaPOLY6 9Calcite No.2samples
Var.1; FN:PC04 72% Homogeneous,optically active,reddish‐brown. Iron‐richparticles 3% Meso‐andmicro‐ channelsand planarvoids, randomly oriented
25CalciteQuartz,micaTRI2.5 Var.2; FN:PC01
77% Homogeneous,optically active,yellowish‐ brown.Iron‐rich particles 3% Meso‐vughsand channels, parallel 20Calcite,biotite,fine‐ grainedbiotite‐rich granite Carbonaterock,quartz,mica, feldspar,biotite
TRI2.5 Note:Variants1and2(var.1,var.2)aredistinguishedbythepresenceorabsenceofadditionaldiscriminantlithologiesand/ordifferencesamongthedominant‐to‐commonfraction.Theterminologyusedfor matrixandvoiddescriptionisbasedonQuinn(2013).Theapproximateamountofclastswasdeterminedbyvisualestimationusingcommoncomparisoncharts.Themineralogyofaplasticinclusionwas ascertainedbymeansofpolarizationmicroscopyandQEMSCAN®. Abbreviations:BB,BellBreaker;BI,bimodal;EBA,EarlyBronzeAge;FN,FinalNeolithic;GSD,grainsizedistribution;POLY,polymodal;TRI,trimodal;U,unimodal.
F I G U R E 4 (See caption on next page)
5.1.4 | Fabric 4: Weathered granite
This fabric was documented in two EBA samples (monument MV) (Table 2). The matrix is heterogeneous and yellowish‐brown in color and displays a slight to moderate optical activity. A paucity of Fe particles is observed in the groundmass. Macro‐and meso‐ vughs and planar voids are randomly oriented or parallel to the pot's walls. The subrounded to subangular equant and poorly sorted elongate inclusions of highly weathered igneous rocks (Figures4gand5, Table2) characterize this fabric. The grain size distribution is trimodal.
5.1.5 | Fabric 5: Epidote granite
Only one BB sample from monument MVII is featured by fabric 5 (Table2). The groundmass is homogenous, brownish‐red, opti- cally active, and rich in Fe‐rich particles (ilmenite, Fe oxide, and siderite). The voids comprise randomly oriented meso‐vughs.
Inclusions of epidote granite are angular to subangular with sizes ranging from coarse to fine sand and with equant or elon- gated shapes (Figures 4h and 5). Epidote overgrowths on the former biotite as well as plagioclase and infillings of Fe‐rich phyllosilicate were observed in polygonized quartz crystals. The grain size distribution is bimodal.
5.1.6 | Fabric 6: Quartz – feldspar gneiss
The samples of this fabric belong to the EBA pottery corpus from monuments MV and MXI (Table2). Its groundmass is het- erogeneous, brown and reddish‐and/or yellowish‐brown in color, with slight to moderate optical activity (Figure 4i,j). A few particles of Fe oxide may be observed in the matrix. According to their shapes, the voids are vughs, channels, and planar, and their sizes are mega, macro, and meso with a random or parallel or- ientation. The quartz–feldspar gneiss presence defines this group (Figures4i,jand5, Table2). Gneiss inclusions range from gravel‐ to sand‐sized and are characterized by equant and elongate shapes with angular to subrounded edges (Table2). In this group, the sand‐sized rounded inclusions of fine‐grained granite accompanied by secondary calcite were also documented (var.
1; see Table 2). The grain size distribution is bimodal to trimodal.
5.1.7 | Fabric 7: Amphibole gneiss
Samples of this fabric belong to the EBA pottery corpus from monuments MVI and MXI (Table 2). Their heterogeneous matrix displays slight to moderate optical activity and is brown or reddish‐ brown in color. The presence of Fe oxide and/or siderite is scarce.
The macro‐to meso‐sized voids are either vughs, channels, or planar voids, with a random or parallel orientation. High‐grade meta- morphic rock fragments of amphibolite facies (amphibole gneiss) define this fabric (Table 2). These inclusions are gravel‐sized to medium sand‐sized, equant and elongate in shape, with an angular to subangular degree of roundness. Gneiss inclusions are rich in albite and quartz, magnesio‐to ferro‐hornblende and accessory minerals such as epidote and titanite (Figures4k,land5). QEMSCAN®geo- chemistry of amphibole revealed its growth on a pyroxene substrate, which may be a sign of metamorphosis of the mafic protolith or alternatively denotes retrogressive metamorphism (e.g., Godard et al.,1981). Moreover, granitic fragments are documented in those samples belonging to variant 2 of this fabric (Table 2). They are gravel‐sized to medium sand‐sized, equant and elongate, with an- gular to subrounded edges. The grain size distribution is bimodal to trimodal.
5.1.8 | Fabric 8: Glaucophane schist
This fabric is reported solely in one sample of the FN ceramic as- semblage from monument MVI (Table2). Its groundmass is homo- geneous and black‐colored. The degree of optical activity was difficult to assess due to the dark hue of the clay matrix. Voids are macro‐ and meso‐sized and vughular‐ and planar‐shaped, all ran- domly oriented. The aplastic inclusions consist of glaucophane schist (Figures4mand 5, Table2). Its mineral composition accounts for albite, epidote, chlorite, calcite, quartz, Fe oxide, and ferro‐ glaucophane. Apatite and titanite are accessory minerals. Rock fragments are poorly sorted, with sizes ranging from sand to pebble.
Inclusions are angular to subrounded with equant and elongate shapes. The grain size distribution is polymodal.
5.1.9 | Fabric 9: Calcite
This fabric accounts for two samples from the FN pottery corpus from monument MVI (Table2). They have a homogeneous yellowish‐or
F I G U R E 4 Microphotographs of selected Petit‐Chasser pottery representative of the distinct fabrics: (a) quartz and feldspar (PC79);
(b) granite var. 1 (PC69); (c) granite var. 2 (PC49); (d) fine‐grained granite rich in Fe oxide var. 1 (PC74); (e, f) fine‐grained granite rich in Fe oxide var. 2 (PC80 and PC21); (g) weathered granite (PC56); (h) epidote‐rich granite (PC73); (i) quartz–feldspar gneiss var. 1 (PC48);
(j) quartz–feldspar gneiss var. 2 (PC63); (k) amphibole gneiss var. 1 (PC17); (l) amphibole gneiss var. 2 (PC33); (m) glaucophane schist (PC05);
(n) calcite var. 1 (PC04); (o) calcite var. 2 (PC01). All photomicrographs were taken with cross‐polarized light at ×2.5 magnification (image width 5.3 mm) [Color figure can be viewed atwileyonlinelibrary.com]
F I G U R E 5 QEMSCAN® mineralogical maps of selected Petit‐Chasser pottery representative of the distinct fabrics: PC79 quartz and feldspar; PC69 granite var. 1; PC49 granite var. 2; PC74 fine‐grained granite rich in Fe oxide var. 1; PC80 and PC21 fine‐grained granite rich in Fe oxide var. 2; PC56 weathered granite; PC73 epidote‐rich granite; PC48 quartz–feldspar gneiss var. 1; PC63 quartz–feldspar gneiss var. 2;
PC17 amphibole gneiss var. 1; PC33 amphibole gneiss var. 2; PC05 glaucophane schist; PC04 calcite var. 1; PC01 calcite var. 2. The arrows indicate the position and the orientation of the horizontal voids [Color figure can be viewed atwileyonlinelibrary.com]
reddish‐brown groundmass and are slightly optically active, with some Fe‐rich particles present in the matrix (Figure4n,o). Meso‐and micro‐ vughs, channel, and planar voids are observed. Some horizontal‐ oriented voids are reported (Figure5). Samples are rich in unsorted silt to gravel fragments of angular to subangular sparitic calcite, elongated to equant in shape (Figures 4n,o and 5). PC01 contains, in addition to calcite, inclusions of sand‐sized equant, angular to subrounded, biotite‐rich granite. The grain size distribution is trimodal.
5.2 | QEMSCAN
®modal mineralogy
Most of the analyzed samples are rich in rock fragments composed mainly of quartz and feldspar, making the potsherds' modal miner- alogy somewhat similar. Primary discrepancies were, however, de- tected in the content of major (quartz, plagioclase, and K‐feldspar) and minor (biotite, carbonates, chlorite, epidote, diopside, and Fe oxide) minerals (Figure6). The carbonate abundances are controlled by calcite inclusions (fabric 9, Tables2and3) and secondary calcite precipitation observed in some granite inclusions (fabric 2 var. 1 and fabric 4, Tables2and3). Fabrics 5 and 8 display a peculiar modal mineralogy marked by an elevated content of epidote and Fe oxide.
Glaucophane schist present in fabric 8 is rich in chlorite, which ex- plains the relatively high chlorite budget of this group (Tables 2 and3). Regarding the ceramic matrix, the QEMSCAN®analyses re- vealed it to be largely made of 10 Å phyllosilicates (Figure 5and Table 3), which consisted of illite and some minor muscovite (Figure5and Table3). An additional micaceous phase, low in K (<5%
K2O), was also detected (Figure5and Table3). The illite/muscovite
ratio varies throughout the sample set, whereas K‐poor mica is rarely identified (Figure5and Table3).
The mineralogical differences discussed above are responsible for matrix heterogeneities, which are documented by polarization microscopy. Moreover, the variations in clay matrix composition (i.e., 10 Å phase speciation) do not correlate with the distribution of specific aplastic inclusions and fabric. Analog illite/muscovite ratios may be found in both the granite‐rich and gneiss‐rich pottery (Figure5and Table3). Similarly, matrices rich in K‐poor mica are found in fabrics 2, 3, and 6 (Figure 5and Table 3). Peculiar clay matrix compositions were reported in the BB sample PC73 of fabric 5 (Figure 5 and Table 3). This sample is abundant in an Fe‐rich phyllosilicate not documented in the rest of the Petit‐Chasseur sample set.
Polarization microscopy identified an abundance of iron‐rich particles, which are important colorants in ceramic ware (Table2).
QEMSCAN®analysis showed they are largely Fe oxide, siderite, or ilmenite (Figure5and Table3). Their total content is generally below 0.1%, except for fabrics 3, 5, and 8 where their sums are ~0.5%,
~0.7%, and ~0.6%, respectively (Table3). These phases are present in lithic fragments and the groundmasses of fabrics 3 and 5 (Table2).
However, the Fe oxide detected in fabric 8 appeared exclusively in aplastic inclusions.
5.3 | Mineralogy and microtexture of ceramic matrix
The XRD investigation provided further insights into the composition of Petit‐Chasseur potsherds. Those most representative of the
F I G U R E 6 QEMSCAN® modal mineralogy of clasts for each fabric [Color figure can be viewed atwileyonlinelibrary.com]
TABLE3QEMSCAN®mineralogyofselectedsamplesindicativeofthedistinctcompositionsofthePetit‐Chasseurpotterywithreferencetoaplasticinclusionsandclaymatrices Fabric QEMSCAN® mineralogy
Quartz and feldspar
Granite var.1 Granite var.2
F.grain granite withFe oxide var.1
F.grain granitewith Feoxide var.2 Weathered granite Epidote granite Quartz–feldspar gneissvar.1 Quartz–feldspar gneissvar.2 Amphibole gneiss var.1 Amphibole gneiss var.2 Glaucophane schist Calcite var.1
Calcite var.2 PC79PC69PC49PC74PC80PC21PC56PC73PC48PC63PC17PC33PC05PC04PC01 Illite44.7342.2828.4821.0617.8512.3849.665.9948.9715.6633.4633.9217.6442.7837.06 Muscovite0.670.1913.9522.3910.0333.100.620.850.0426.650.130.469.650.652.90 Chlorite4.420.251.840.854.231.530.29‐0.102.650.932.4015.500.293.42 Quartz21.8727.3314.9432.2324.8018.4720.9411.3026.4119.0442.4021.2910.948.2714.40 K‐poormica0.200.044.732.887.526.770.604.780.018.620.040.162.850.202.07 Fe‐rich phyllosi- licate
‐‐‐‐‐‐‐49.38‐‐‐‐‐‐‐ Plagioclase6.0311.6014.724.619.008.775.705.477.196.8210.3215.1314.772.098.87 K‐feldspar2.515.905.560.427.744.576.560.473.506.250.254.73‐0.292.78 Biotite0.670.080.450.210.420.470.680.300.050.880.104.510.610.142.92 Calcite0.010.140.13‐0.370.073.790.010.030.020.120.613.8628.205.83 Dolomite‐‐‐‐‐‐‐‐0.49‐‐0.120.010.010.01 Epidote0.07‐0.110.100.130.080.154.260.290.090.880.387.350.180.52 Siderite0.040.010.420.580.330.010.08‐0.900.020.030.030.020.04 Feoxide0.010.090.030.130.030.050.020.260.010.150.130.050.620.010.05 Ilmenite0.030.010.020.01‐‐‐0.40‐‐0.01‐0.030.010.01 Amphibole/Fe oxide‐‐‐‐‐‐‐3.18‐‐‐‐‐‐‐ Diopside‐‐‐‐‐‐‐0.01‐‐0.380.050.01‐‐ Titanite0.01‐0.010.030.020.010.030.010.030.020.280.092.000.030.12 Unclassified1.220.201.150.841.701.050.46‐0.201.251.341.692.300.651.67 Others1.040.131.360.652.331.230.360.070.122.10.260.241.670.420.63 Voids16.4711.7512.5213.1713.2511.1210.1312.5512.568.908.9514.1410.1615.7616.70 Total(%)100100100100100100100100100100100100100100100
TABLE4XRDandSEM‐EDSmineralogyofPetit‐Chasseurpottery;SEM‐EDSmeasurementsrefertoceramicmatrixonly SamplePetrographicgroupQEMSCAN®matrixXRDSEM‐EDS PC01Calcitevar.2IlliteChl,10Åmica,Qtz,Kfs,Ab,Caln.a. PC04Calcitevar.1IlliteChl,10Åmica,Qtz,Ab,Caln.a. PC05GlaucophaneschistMainlyillite,muscoviteChl,10Åmica,Qtz,Ab,Cal,Am,Ep,HemMuscovitewithsomecasesofillitization PC11Granitevar.1IlliteChl,10Åmica,Qtz,Kfs,Ab,Mc,Cal,Hemn.a. PC32Amphibolegneissvar.1Mainlyunclassifiedclaymineraln.a.Vermiculitizedmica PC38Granitevar.1IlliteChl,10Åmica,Qtz,Kfs,Ab,Hemn.a. PC48Quartz–feldspargneissvar.1IlliteChl,10Åmica,Qtz,Kfs,AbIllite(smectitization),illite/mica PC49Granitevar.2Illite,muscovite10Åmica,Qtz,Mc,Abn.a. PC56WeatheredgraniteIlliteChl,10Åmica,Qtz,Kfs,Ab,Cal,HemIllite PC59Quartz–feldspargneissvar.2Illite,muscoviteChl,10Åmica,Qtz,Kfs,Mc,Ab,Hemn.a. PC63Quartz–feldspargneissvar.2Muscovite,illite,K‐poormica10Åmica,Qtz,Mc,AbK‐poormica,illite,raresmectite PC66Quartz–feldspargneissvar.1IlliteChl,10Åmica,Qtz,Kfs,Mc,Ab,HemIllite,muscovite PC69Granitevar.1IlliteChl,10Åmica,Qtz,Kfs,Mc,Ab,Hemn.a. PC71Fine‐grainedgraniterichinFeoxidevar.2IlliteChl?,10Åmica,Qtz,Ab,Mc,Hemn.a. PC73Epidote‐richgraniteFe‐richclayminerals10Åmica,Zeo,Am,Qtz,Ab,Ep,HemAl‐richstilpnomelane PC74Fine‐grainedgraniterichinFeoxidevar.1MuscoviteandilliteChl?,10Åmica,Qtz,Ab,Cal?n.a. PC77Fine‐grainedgraniterichinFeoxidevar.2IlliteandmuscoviteChl,10Åmica,Qtz,Kfs,Ab,Hemn.a. PC79QuartzandfeldsparIlliteChl,10Åmica,Qtz,Mc,Ab,Hemn.a. PC80Fine‐grainedgraniterichinFeoxidevar.2Illite,muscovite,andK‐poormican.a.K‐poormica,fewillite,raresmectite Note:MineralabbreviationaftertheSubcommissionontheSystematicsofMetamorphicRocks(SCMR):Ab,albite;Am,amphibole;Cal,calcite;Chl,chlorite;Dol,dolomite;Ep,epidote;Hem,hematite;Kfs, K‐feldspar;Mc,microcline;Qtz,quartz;Zeo,zeolite. Abbreviations:n.a.,noanalysis;SEM‐EDS,scanningelectronmicroscopy–energy‐dispersivespectroscopy;XRD,X‐raydiffraction.
corpus are largely made up of 10 and 14 Å phyllosilicates (illite/mica and chlorite, respectively), quartz, albite, and K‐feldspar (Table4).
The presence of carbonate is reported in 5 samples (fabric 2 var. 1, fabrics 4, 8, and 9; Table 4) and that of hematite in 11 samples (fabrics 1–6 and 8; Table4). Calcite is related to dominant/frequent aplastic inclusions (Table2), whereas hematite may be related to both the lithic fragments (e.g., fine‐grained granite with Fe oxide;
Table2) and Fe particles present in the ceramic matrix (Table 2).
Amphibole and epidote occur in PC05 and PC73 (Table4), which is in line with the nature of rock fragments documented in these samples (fabrics 5 and 8; Table2). Sample PC73 is further distinguished from other samples by zeolite presence and high hematite content. X‐ray diffraction points out two phyllosilicates (illite/mica and chlorite) as plausible constituents of the ceramic matrix, which correlates well
with the QEMSCAN® mineral mapping (Figure 5). However, the latter showed that 14 Å phyllosilicates are generally related to rock inclusions and not to the matrix per se. This enables one to infer that the clay matrix, as a whole, is essentially made of 10 Å phyllosilicates (i.e., mica, illite, or mixed‐layer [mica‐rich] mica–smectite).
Acquired EDS spectra indicate the matrix of samples PC56, PC66, and PC48 (fabrics 4 and 6) to be largely composed of illite (Figure7and Table5). Sample PC48 is characterized by the ongoing smectitization of its illitic base and formation of mixed‐layer illite–smectite (Si–Al ratio ~1/4, Table5). The presence of detrital mica–illite was also found in this sample (Figure 7 and Table 5).
Conversely, the matrix of PC05 (fabric 8) is mainly composed of muscovite with some minor illite presumably formed through the alteration of muscovite (Figure7and Table5). Samples PC63
F I G U R E 7 Backscattered image of typical SEM‐EDS ceramic matrices: PC56, illite—petrographic group Weathered granite; PC48, illite (smectitization) and illite/mica—petrographic group Quartz–feldspar gneiss; PC05, muscovite with some cases of illitization—petrographic group Glaucophane schist; PC63, K‐poor mica, illite, rare smectite—petrographic group Quartz–feldspar gneiss; PC32, vermiculitized mica— petrographic group Amphibole gneiss; PC73, Al‐rich stilpnomelane—petrographic group Epidote‐rich granite. EDS chemistry may be found in Table5
TABLE5ExemplaryEDSchemistryoftheceramicmatricesillustratedinFigure7 SamplePC56PC56PC56PC56PC56PC48PC48PC48PC05PC05PC05PC05 MineralIllite(IL)Illite(IL)Illite–smectite(A)Chlorite(B) Weathered mica(C) Illite (smectitization) (D) Illite (smectitization) (D) Weathered mica(C) Muscovite (illitization) (E) Muscovite (illitization) (E)
Illite (alteration productof muscovite) (F)Chamosite(G) Spectrum568555571564561314314309367382371368 SiO254.057.646.549.753.169.669.653.449.652.060.429.5 Al2O327.424.820.525.627.417.817.826.332.629.824.427.8 K2O6.55.13.12.38.74.54.511.96.59.35.21.4 FeO5.95.514.32.75.73.23.25.16.56.64.634.1 MgO4.65.413.418.14.13.83.83.31.22.31.16.8 CaO1.11.31.31.6‐0.80.8‐1.9‐1.20.5 TiO20.60.30.9‐0.90.30.3‐0.5‐2.3‐ MnO‐‐‐‐‐‐‐‐‐‐‐‐ Na2O‐‐‐‐‐‐‐‐0.5‐0.4‐ SO‐‐‐‐‐‐‐‐0.6‐0.3‐ P2O5‐‐‐‐‐‐‐‐‐‐‐‐ Total100.110010010099.910010010099.910099.9100.1 SamplePC63PC63PC63PC32PC32PC32PC73PC73PC73PC73 MineralK‐ poor mica (H)
Muscovite(M)Illite(IL)Vermiculitizedmica(I)Vermiculitizedmica(I)Muscovite(M)Al‐rich stilpnomelane(J) Al‐rich stilpnomelane(J) Muscovite (smectitization) (K)
Muscovite (smectitization)(K) Spectrum454451462487493500159171166170 SiO254.750.665.455.758.051.050.842.354.873.7 Al2O330.537.223.220.118.535.039.632.329.715.8 K2O4.69.23.85.15.810.10.60.80.70.3 FeO4.91.84.74.84.72.04.220.410.87.0 MgO1.20.80.912.410.51.41.81.62.11.1 CaO2.1‐1.71.32.1‐2.31.81.51.3 TiO21.6‐‐0.70.4‐‐0.50.40.9 (Continues)
(fabric 6) and PC80 (fabric 3) are rich in K‐poor mica (<5% K2O) and some minor illite and smectite. Sample PC32 (fabric 7) contains a vermiculitic phase likely formed of a micaceous precursor and smectite (Figure7and Table5). The peculiarity of PC73 (fabric 5), suggested by OM, QEMSCAN®, and XRD analyses, is further cor- roborated by SEM‐EDS analyses unveiling the matrix composed of Al‐rich stilpnomelane (<5% K2O, Fe2O3 ~32%–20.4%, and CaO
~1%–2.7%; Figure7and Table 5). SEM‐EDS analyses proved that 10 Å phyllosilicates, which constitute the matrix, cannot be linked with the type of plastic inclusions but rather reflect different areas of the raw material procurement.
5.4 | Pottery geochemistry
The raw geochemical data (Supporting Information Material S3) were studied to identify the element concentration patterns char- acteristic for Petit‐Chasseur ceramics. Most of the analyzed pot- sherds have SiO2content exceeding ~50 wt%, Al2O3~15 wt%, and CaO below 5 wt%, except for samples PC03 and PC04 (CaO ~22 wt
%, taken from the same FN vessel). The amounts of Fe2O3, MgO, and TiO2vary considerably (~2–10, ~0.5–4, and 0.3–2 wt%, respectively), whereas K2O and Na2O contents range between 0.5 and 5 wt% and 0.1 and 2.7 wt%. Minor amount of P2O5(<0.7 wt%) may be attributed to postdepositional alteration (Freestone et al., 1985; Schwedt et al.,2004). Considering a myriad of inclusions in analyzed ceramics consisting quartz, feldspar, and rock fragments (fabrics 1–7, 8, and 9;
Table2), the SiO2–Al2O3–Na2O–K2O versus CaO (Figure8a) and SiO2–Al2O3–Na2O–K2O versus Fe2O3–MgO–TiO2(Figure8b) plots were utilized to discriminate between studied samples. The outliers are marked by either higher CaO or Fe2O3and TiO2, which is cor- related with their respective petrographic groups impoverished in felsic component (Tables2and 3; Supporting Information Materi- alS3). Rare earth elements (REE) were found to highly discriminate the Petit‐Chasseur ceramics (Figure 8c). They range from 108 to 343 ppm, forming the two arbitrary defined groups: low‐REE and high‐REE ceramics (Figure8d).
The PCA based on major elements only shows the first three components to account for 80.2% of the total variance (40.7%, 25.3%, and 14.2%, respectively; Figure9a,b). The FN and some of the BB samples are impoverished in the felsic component (Figure8a,b) and clearly differ from the main projection field (Figure9a,b). This is due to their petrographic composition, featured by the calcite, the epidote‐rich granite, or the glaucophane schist present in the cera- mic paste (Table2). On the contrary, EBA potsherds and the re- maining BB samples displayed different fabrics, and are thus enriched in felsic component (Figure8a,b; Supporting Information Material3). Consequently, they cluster into the same projection area (Figure9a,b).
The information provided above accentuates the importance of inclusions, which effectively control the total geochemical budget of analyzed potsherds. This is attributed to a high abundance of aplastic inclusions (Figure4and Table2) and their relative chemical fertility TABLE5(Continued) SamplePC63PC63PC63PC32PC32PC32PC73PC73PC73PC73 MineralK‐ poor mica (H)
Muscovite(M)Illite(IL)Vermiculitizedmica(I)Vermiculitizedmica(I)Muscovite(M)Al‐rich stilpnomelane(J) Al‐rich stilpnomelane(J) Muscovite (smectitization) (K)
Muscovite (smectitization)(K) Spectrum454451462487493500159171166170 MnO‐‐‐‐‐‐‐‐‐‐ Na2O0.40.50.3‐‐0.5‐0.3‐‐ SO‐‐‐‐‐‐0.3‐‐‐ P2O5‐‐‐‐‐‐0.4‐‐‐ Total100100.1100100.1100100100100100100
with regard to an Si–Al‐based matrix. This becomes even more ap- parent when PCA is applied to a subset of samples for which the lithological assemblage is known (Figure9c,dand Table2). There, the first three components account for 80.9% of the total variance (40.9%, 24.0%, and 16%, respectively; Figure 9c,d). As previously noted, samples of the calcite group (fabric 9; Table2) and those rich in Fe‐bearing glaucophane schist and epidote‐rich granite (fabrics 8 and 5; Table2) are outliers. The oscillations in the amount of fine‐ grained granite with calcite infills define the patchy distribution of the pottery of the granite and quartz–feldspar gneiss groups (fabrics 2 and 6, respectively; Table2). Both of these groups are marked by petrographic heterogeneities in terms of the type and number of inclusions (fabric 2 var. 1 and fabric 6 var. 1; Table2), which, in turn, controls their whole‐rock geochemistry and scattered distribution in PCA biplots. The projection areas of other fabrics seem to be more homogenous (Figure 9c). The position of the weathered granite group (fabric 4; Table 2) is defined by CaO enrichment due to a secondary calcite infill of igneous aplastic inclusions. Projections of
the amphibole gneiss‐rich pottery (fabric 7; Table 2) are largely defined by a uniform abundance of their inclusions consisting of plagioclase, amphibole–pyroxene pseudomorphs, and epidote (Figure5). Finally, the projection of fine‐grained granite pottery with Fe oxide (fabric 7; Table2) along the first principal component has been defined by the steady increase of its Fe content (Figure9c,d).
The Petit‐Chasseur pottery serves as a good example of how dif- ferent aplastic inclusions control the overall geochemical makeup of ceramic vessels. This adds to the importance of temper and natural inclusions when it comes to pottery classification and reconstruction of the procurement of raw material (Brunelli et al., 2013; Day et al.,2011; Salanova et al.,2016).
The REE‐based PCA (84.6% of the total variation for the first three components) pointed out a lack of correlation between the inclusion types (i.e., fabrics) and REE abundances (Figure 10a,b).
This means that the trace element budget of analyzed pottery is essentially controlled by the clay matrix substrate (e.g., Michard,1989). This holds true for REE in particular, which tends to F I G U R E 8 Bivariate plots discriminating the Petit‐Chasseur ceramics: (a) SiO2–Al2O3–Na2O–K2O versus CaO; (b) SiO2–Al2O3–Na2O–K2O versus Fe2O3–MgO–TiO2; (c) SiO2–Al2O3–Na2O–K2O–CaO–Fe2O3–MgO–TiO2versus REE; (d) LREE versus HREE. BB, Bell Breaker; EBA, Early Bronze Age; FN, Final Neolithic; HREE, heavy rare earth element; LREE, light rare earth element; SEM‐EDS, scanning electron
microscopy–energy‐dispersive spectroscopy [Color figure can be viewed atwileyonlinelibrary.com]
be allocated to reactive surfaces of the clay minerals (e.g., Andersson et al.,2004;Šegvićet al.,2014). There is a relatively recent experimental study showing that temper effects on the total budget of trace elements in pottery are negligible (Munita et al.,2008). Moreover, it has also been demonstrated that even the firing process does not significantly alter the initial clay composition (Gutsuz et al.,2017). The PCA biplot with indicated sample pro- jections whose clay matrix had been investigated by SEM‐EDS of- fers further inferences (Figure10cand Table4). The matrices made of mica are intrinsically enriched in both LREE and HREE (Figure 10d; high‐REE group, Figure 8d), whereas the opposite holds true for those which are illite‐based (Figure 10d; low‐REE group, Figure8d). This is attributed to a higher charge of micaceous
phases that promote a retention of REE (e.g., Andersson et al.,2004), whereas lower charges and an ongoing smectitization of illite reduce its capability to attract REE (Honty et al.,2008;
Zanoni & Šegvić,2019). The behavior of high‐field strength ele- ments (HFSE) is analogous to that of REE (85.9% of the total var- iance for the first three components; Figure 10e,f); mica‐based matrix is richer in HFSE as compared with the one consisting of illite. The only exceptions are samples PC05 and PC73, which are rich in TiO2, though this does not stem from the matrix but rather makes up part of rock inclusions (Table2).
The normalization to the NASC allows for an inspection of ele- mental concentrations with respect to the standard (Figure 11).
Other than the major elements (Al2O3, Fe2O3, CaO, Na2O, K2O, and F I G U R E 9 Statistical treatments of geochemical data of analyzed pottery: (a) and (b) principal component analysis (PCA) performed on the entire ceramic data set considering major and minor element content—principal component biplot; (c) and (d) PCA performed only on the 42 samples for which the lithological assemblage is known, major and minor element content—principal component biplot [Color figure can be viewed atwileyonlinelibrary.com]
F I G U R E 10 (See caption on next page)
