XRF OBSIDIAN ANALYSIS FROM BASIN, HUAMANGA PROVINCE, SOUTHEASTERN Martín Giesso1+, Hugo G. Nami2, Juan J. Yataco Capcha3, Michael D. Glascock4, Brandi L. MacDonald4 1Department of Anthropology, Northeastern Illinois University, Chicago, Il. 60625 2CONICET-IGEBA, Laboratorio de Geofísica “Daniel A. Valencio”, Departamento de Ciencias Geológicas, FCEN, UBA, Ciudad Autónoma de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina. 3Museo de Arqueología y Antropología, Universidad Nacional Mayor de San Marcos, Perú 4Archaeometry Laboratory, Research Reactor Center, University of Missouri, Columbia, MO, 65211.

KEYWORDS: OBSIDIAN SOURCING, XRF, SOUTHERN , PERU.

+ Corresponding author: [email protected] Abstract In , obsidian was broadly used along the Andean Cordillera from North to South. Particularly in Peru, its use can be traced to the earliest human occupations, continuously through pre-Columbian times, to contemporary Andean agro-pastoralist societies. With the aim of distinguishing the provenance of obsidians from this country, this article reports new XRF analysis on a number of obsidians obtained in surface collections of the Ayacucho region. The analysis and source determination were made by XRF on 52 artifactsThe source assignments involved comparisons between the compositional data for the artifacts and the University of Missouri Research Reactor (MURR) XRF obsidian database for sources in Peru. After analyzing the sample, several obsidian sources were recognized and documented, all of them with small nodules not larger than ~4 cm which were recovered at Ñahuinpuquio and Marcahuilca hill that belong to the previously identified Puzolana source. Another identified source is the well known Quispisisa, which is placed 120 km south of the city of Ayacucho, and distributed through a vast region in central Peru. The results presented in this paper expand previous observations on the obsidian provenance at the Ayacucho Basin, and also expands the extension of the Puzolana source between Yanama and Huarpa hills, south of Ayacucho city.

1. INTRODUCTION

In South America, obsidian was broadly used along the Andean Cordillera from North to South (e.g. Bigazzi et al. 1992; Hurliman 1993; Salazar 1992, Burger et al. 1994; Seelenfreund et al. 1996; Dorighel et al. 1999; Stern et al. 2000; Bellot-Gurlet el. 2002, Durán et al. 2004, 2012; Bellot- Gurlet et al. 2008; Ogburn et al. 2009; Ogburn 2011; Giesso et al. 2011; Cortegoso et al. 2012; Nami et al. 2015; among others). Particularly in Peru, its use can be traced to the earliest human occupations (e.g. MacNeish et al. 1980, 1981, 1983; Rademaker et al. 2014; Sandweiss et al. 1998; Yataco Capcha and Nami 2016), continuously through pre-Columbian times, to contemporary Andean agro- pastoralist societies (Burger and Asaro 1978, 1979; Brooks, Giesso and Glascock 1997). In order to characterize archaeological obsidian sources and provenance, diverse lines of investigations have been developed in Peru since the late 1970s (Burger 2006, Burger and Asaro 1979, 1982, 1993, Burger et al. 1998a,b,c; 2000a,b, 2006a,b, 2016; Burger and Glascock 2000a,b, 2002; Stanish et al. 2002; Jennings and Glascock 2002; Tripcevich 2009, 2010, 2011; Eerkens et al. 2010; Matsumoto et al. 2017). With the aim of distinguishing the provenance of obsidians from this Andean country, this article reports new XRF analysis on a sample of several obsidian artifacts from different sites of the Ayacucho region, south of Huamanga province, in the southeast of the country (Figure 1).

Figure 1. Location map of the Ayacucho Basin and sample locations in southeastern Peru.

2. ARCHAEOLOGICAL BACKGROUND The Ayacucho Basin in southeastern Peru is a well-studied area in South American archaeology because during 1969-1972, a significant number of sites were discovered and studied by the interdisciplinary “Ayacucho Archaeological Botanical Project” (MacNeish 1969; 1971; 1976; 1978; MacNeish et al. 1970, 1980; 1981; 1983). In order to reevaluate and build on these previous investigations we analyzed a number of obsidian specimens collected in new research activities performed in Ayacucho. In this region the terrain is rugged and the geomorphology is the result of successive volcanic events that were subjected to fluvial erosional processes, eventually giving rise to the Ayacucho Basin (Morche et al. 1995:15). In our search for obsidian first we carefully studied the geological information (Morche et al. 1995:17-18). In this endeavor, two zones located north and south of Ayacucho city were surveyed (Figures 2 and 3). The northern area includes the Pacaicasa district, were we explored the eastern slope Marcahuilca hill and Pampachacra. There, at the Molinoyoq Formation (Nm-mo in Figure 2) five volcanic cones that reach altitudes of approximately 3,400 masl were detected. The explorations have been carried out at the foot of the Marcahuilca hill and about 800 meters from the Pikimachay cave (Figure 2:1). Also to the east a volcanic cone was recorded in the Huari Formation where the Huari/Wari archaeological site was built (Np-hu in figure 2: Sample field Nº2). Pampachacra is an extension of the Huari urban site, in the middle of terraces and cultivation areas obsidian debris was collected in the Ayacucho Formation (Nm-ay1 in Figure 2:3). To the south, in the Carmen Alto district, the explorations were performed between the Huari and Ayacucho Formations (Np-hu and Nm-ay1, Figure 2: 4), and seven volcanic cones registered near Ayacucho city (Morche et al. 1995: 17-18). Localities such as San Juan Bautista, Ñahuinpuquio, Cerro Yanama and Cerro Huarpa were surveyed (Figure 2-3). The prospected areas are composed of volcanic rocks, sediments, tobaceous and calcareous white scabs that surround the flanks of the volcanic cones (Morche et al. 1995; see Figure 3). In these areas, obsidian samples as natural nodules and artifacts were found. In general the nodules showed small dimensions mostly ranging between ~1 to 3-4 cm. As seen in Figure 4, the archaeological vestiges are represented by small tools, cores and debitage mostly of black and smoky translucent obsidian; however, one specimen of the “mahogany” variety was found. Salient information on the sites where obsidians were recovered is summarized in Table 1.

Figure 2. Explored area in the Ayacucho basin (modified after Morche et al. 1995).

Figure 3. General view of Marcahuilca hill where the Pikimachay cave (a) and Huarpa hill (b) are located.

Figure 4. Examples of obsidian nodules and archaeological artifacts from Ayacucho basin. a) in situ nodules at Ñahuinpuquio source, b-c) small archaeological artifacts, probably a core or unifacial tool, d-e) Nodules from Marcahuilca hill (d) and Ñahinpuquio between Huarpa and Yanama hills (e).

Environment Relation with Type of Sample Figure Site Type Site/Locality archaeological sample (n = 52 ) finds

Talus of Archaeological White limestone Lithic flakes Lithic 2.1 artifacts Pikimachay Cave (S) 13°02’18.63” 2

(W) 74°13’41.45”

Slopes of Source East of the Pikimachay cave. 2.1 Surface covered by crusts of Marcahuilca Hill white limestone One nodule - 2 (S) 13°02’33.28” and lithic artifacts (W) 74°13’19.82”

Turquezayoq Archaeological Huari site 2.2 Fragments of Lithic (S) 13°03’23.53” 2 Huari pottery artifacts (W)74°11’55.56” Capillapata Archaeological “ 2.2

(S) 13°03’26.8” “ “ 9 (W) 74°11’57.15”

Pampachacra Archaeological In front of Huari and in the 2.3 (S) 13°03’43.92” middle of cultivation farms “ “ 6 (W) 74’12’0.08” Ñahuinpuquio Canyon Source High zone of Quebrada 2.4 Ñahuinpuquio, between 31 (S) 13º11’42.22” Huarpa and Yanama hills. - Nodules (W) 74°12’27.84”

Table 1. Salient information of the localities where the samples were recovered.

3. MATERIALS AND METHODS The analyzed samples (n = 52) were surface finds recovered during different visits in the late 2000s and systematic surveys carried out between 2015 and 2017. All specimens were analyzed by X-ray fluorescence (XRF) with equipment of the University of Missouri Research Reactor (MURR). The first group set analyzed using a Thermo Quantx ARL desk top, the equipment analyzes Mn, Fe, Zn, Rb, Sr, Y, Zr, Nb, and Th, with 120 second intervals. The second set was processed using a hand- held Bruker spectrometer (Tracer III-V). Peak deconvolution was accomplished using the Bruker spectral analysis package which enabled measurement of thirteen elements in most samples, including K, Ti, Mn, Fe, Zn, Ga, Rb, Sr, Y, Zr, Nb, Pb, and Th. The samples have to be placed individually, and can have any size (the Quantx is covered, so the samples have maximum dimensions) and the cycle lasts 3 minutes. The instruments were calibrated using compositional data from a series of 40 well-characterized source samples in the MURR obsidian reference collection as described in a report by Glascock and Ferguson (2012). Consensus values for the obsidian calibration sources were previously determined at MURR (using both NAA and ICP-MS) and other laboratories (XRF only). Concentration ranges for the reference samples span the range of probable concentrations for obsidian from different sources around the world.

4.0 RESULTS The detailed results by elements and provenience are respectively depicted in Table 2. To determine sources for obsidian artifacts a scatterplot of Rb versus Zr is shown in Figure 5. The results proved satisfactory for determining sources for all the analyzed samples. Thirty-nine of the artifacts came from the Quispisisa source, thirty-four came from Puzolana (Vilcas), and two were unable to be assigned. When analyzing the 3 main elements (Rb, Sr, Zr) we observe that Quispisisa has significantly higher Rb and Sr, but similar amounts of Zr, as seen in Fig 5. Strontium ranges from 100 to 144 ppm in Quispisisa, and from 41 to 75 ppm in Puzolana-Vilcas.

Fig. 5. Scatterplot of Rb versus Zr for obsidian artifacts from sites in Ayacucho, Peru. The source groups at Quispisisa and Puzolana are surrounded by 90% confidence ellipses.

Table 2. Ayacucho obsidian XRF

Figure 6. Map of the possible area of Puzolana obsidian nodules formerly taken by Burger.

To sum up after analyzing the sample, several obsidian sources were recognized and documented, all of them with small nodules not larger than ~4 cm. The largest number of specimens comes from Ñahuinpuquio whose nodules have the fingerprint of the Vilcas source (Burger and Glascock 2000a), which is located within a 5 km radius of the site. According the Burger (pers. comm. 2018) this source is just a geological sample of the Puzolana source (Burger and Glascock 2000a), formerly called Ayacucho type (Burger and Asaro 1979), which originated by a pyroclastic explosion that widely distributed a large quantity of relatively small nodules in different places between Huamanga and Vilcashuaman. Then, the small nodules recovered at Ñahuinpuquio and Marcahuilca hill may belong to the same geologic event. Importantly, at Ayacucho small obsidian nodules not only are found at Ñahuinpuquio and Pampachacra as presented in this paper. Similar obsidian nodules have been found at Campanayocc site, located west of Yanama hill (Burger and Glascock 2000a). Despite the small size of the nodules, they may be adequately reduced using appropriate adapted techniques to its dimensions, hence potentially useful for obtaining flakes. The small cores founded in the area might represent such flaking response to this obsidian appearance. On the other hand, the Quispisisa source is located outside of the Ayacucho valley. Quispisisa, which contains high quality obsidian, is placed 120 km south of the city of Ayacucho, and was the main obsidian type procured by Chavín and Wari peoples, and distributed through a vast region in central Peru (Burger et al. 2000, Burger et al 2016).

5. Discussion and conclusion In the Ayacucho basin obsidian was used as raw material for making tools, and has been identified from hunter-gatherers Paleoindian to the Late Horizon agro-pastoralist societies (Burger and Asaro 1978, 1979; Brooks, Giesso and Glascock 1997). In our research area MacNeish performed his investigations, as seen in figure 7, finding obsidians at the following sites: Pikimachay (Ac 100), Ayamachay (Ac 102); Puente (Ac 158); Ruyru Rumi (Ac 300), Jaywamachay (Ac 335), Tukumachay (Ac 351) and Chupas (Ac 500) (cf. Burger & Asaro 1977: 285-286; 1993: 191-302; MacNeish et al. 1970). Provenance analysis of a significant number of samples (n = 65) exhumed in some of these sites were previously performed using NAA and XRF analysis. The oldest data regarding the use of this rock by regional settlers comes from the lower levels of Jaywamachay rockshelter dated in 10,280 ± 170 14C yr BP (I-5699), or 12,548–11,325 cal yr BP. in its lower occupation (Yataco Capcha and Nami 2016). From this site, the analysis of a total of 28 obsidian specimens, indicated that its totality comes from Quispisisa source (Burger et al. 1993: 219, cuadro 12). Regarding Ayamachay (Ac102), the obsidians were recovered from strata VI to VIII (MacNeish et al 1981: 117-118) with a radiocarbon date of 7560 ± 125BP (I-5694) from stratum VII. Six obsidian samples were analyzed and the results suggest that they come from Quispisisa (Burger et al. 1993: 219, table 12). At Chupa rock shelter, a total of six obsidian samples from its deepest levels were taken from stratum D-1 to F. Despite that no chronological data was obtained from these strata, morphological comparisons of the lithic artifacts found with the dated findings from stratum VIII at Puente site (Ac158) suggests that the obsidians belongs to the Middle Holocene occupations (MacNeish et al., 1981: 142-143). The results of the analysis indicated that only one sample (taken at layer D-1) come from Puzolana, and the remaining ones were collected at Quispisisa (Burger 1977: 309; 1993: 219). At El Puente (Ac158), twelve samples coming from the strata I, V to IX, and XI to XIII were analyzed. Radiocarbon assays from charcoal collected at strata VI and VIII yielded two respective dates of 7610-7279 (I-5132) and 8150-7685 (I-5054) calibrated yr BP. Most analyzed specimens (n = 11) come from the Quispisisa source and only one from stratum VII comes from the Puzolana source. Ten specimens recovered at Ruyru Rumi site (Ac300) were also processed by Burger and colleagues (1993). The obtained results showed that the obsidians of this site come from Quispisisa (Burger and Asaro, 1993: 219, table 12). From Chupa rock shelter (Ac500), a sample (n = 6) collected in the deepest strata (D-1 to F), probably belonging to the Middle Holocene (MacNeish et al., 1981: 142-143) was analyzed. Their study showed that except one sample from the D-1 stratum coming from the Puzolana, the remaining ones were collected at Quispisisa (Burger 1977: 309; 1993: 215-216). Three obsidian samples were analyzed from Tukumachay cave (Ac351), located south of Tambillo. Results from this analysis indicated that the samples come from the Quispisisa quarry. Finally, from the Pikimachay cave (Ac100) only one sample taken from stratum f2 was analyzed. Apparently its origin has been from the south room, associated with the Jaywa phase and with a relative date that ranges from 7200 to 6600 B.C. (MacNeish et al., 1981: 43-56). Like other samples, the results obtained indicate that it comes from Quispisisa. In summary, previous obsidian studies at Ayacucho basin (Burger & Asaro 1992) proposed that the obsidian selection, exchange and transport over long distances indicating that they come from one main source, Quispisisa, and in much small amounts from Puzolana (Burger and Asaro, 1993: 304; Burger et al., 2000: 258-268). Despite being surface findings, the results presented in this paper expand this observation to include a stronger presence of Puzolana obsidian than Quispisisa. Also expands the extension of the Puzolana source between Yanama and Huarpa hills, south of Ayacucho city. We have to consider the possibility that Puzolana might have been a more important local obsidian source. It is crucial to restudy and re-evaluate the lithic collections assembled by MacNeish and his team between 1969 and 1972 (MacNeish 1969, 1971, 1976, 1978; MacNeish et al. 1970, 1980). Particularly, the obsidians coming from controlled chronological contexts allowing to have a temporal sequence and to know the behavior of its exploitation and distribution through time in the Ayacucho region.

Figure 7. Sites with previous obsidian provenance studies in the Ayacucho area (modified by Yataco Capcha after MacNeish (1981:4; Figure 1-1).

Acknowledgments The Archaeometry Laboratory at MURR receives support in part by a grant from the National Science Foundation (NSF-1621158); H. Nami wish to thank to: Ayni (Arlington, VA., USA) and CONICET (PIP-114-200801-00344) for supporting his field-trip to Ayacucho basin, Oscar Huaman for his help and cooperation during the survey at Ñauinpuqio, Richard Burger for his kindness and help during the processing of this paper. We thank the Human Paleoecology Laboratory of the Universidad Nacional de Cuyo (Argentina), for allowing us to analyze samples using the MURR’s Bruker III-V in use there at the time.

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