The Domeyko mountain range in northern Chile runs from north to south with an average altitude of 3,000 m a.s.l. The study area is characterized by mountainous features, pediplanes and alluvial fans (Ramírez and Gardeweg, 1982). The local lithology comprises Upper Carboniferous to Permian ignimbrites and rhyolitic domes, Triassic lacustrine fossiliferous strata, and Cretaceous to Miocene continental sediments (Marinovic and Lahsen, 1984; Mpodozis et al., 2005). To the northwest of the study area, the Cerros de Tuina range is associated with a set of inverse faults (Henríquez et al., 2014).

The Precordillera rises from the low, flat terrain of the Salar de Atacama to the Andes highlands. It presents irregular topography with a slope of 3-5°º, dissected by a dendritic drainage network of ravines up to 200 m deep (Ramírez and Gardeweg, 1982), and by ranges of small hills such as Cas, Peine and Lila hills. Lithologically, it is characterized by outcrops of Paleozoic, Mesozoic and Cenozoic rocks that include sandstones and shales, andesites, dacites, and tuffs (Niemeyer, 2013).

The Andes consists of an imposing mountain range that extends longitudinally from north to south, formed by volcanic features, domes, and hills set on the rhyolitic plateau. In the study area, this unit includes: 1) The Western Cordillera that reaches 6,800 m a.s.l, consisting mainly of Cenozoic volcanic rocks and characterized by a strip of stratovolcanoes overlying older ignimbritic layers (Allmendinger et al., 1997); and 2) the Altiplano or Puna, an extensive ingimbritic plateau that extends through northeastern Chile, Argentina, Peru, and Bolivia at a mean altitude of 4,000 m a.s.l (Isacks, 1988). Locally, the volcanic deposits are formed mainly by ignimbrites, volcanic complexes, and aerial pyroclastic deposits from the Upper Miocene to the Quaternary. The ignimbrites are made up of tuffs of different degrees of welding, mainly dacitic and rhyolitic in composition (Gardeweg and Ramírez, 1985). The stratovolcanoes and stratified volcanic sequences show an andesitic and subordinately basaltic and dacitic composition and, to a lesser extent, pyroclastic cones, domes, and subcircular structures (craters) of rhyolitic composition. Upper pre-Miocene intrusive and folded sedimentary rocks appear in erosion windows and isolated hills (Gardeweg et al., 1998).

The lithological classification of lithic assemblages identified a wide diversity of rocks, most of them of volcanic and subvolcanic origin, forming a rich and varied lithic assemblage (Figure 2). The main types identified were obsidian, cherts, and other siliceous rocks, andesites and tuffs, in addition to other minorities such as basalts, dacites, pumices, micro-diorites, and granitic and porphyritic rocks, among many others. A count of the rock classes and sub-varieties (with their respective codes used hereinafter) is presented in Table 2. Among the predominant rocks, obsidian was clearly much sought-after, being used mainly in the manufacture of projectile points and micro-perforators (Figures 2A–C). The obsidian class breaks down into several sub-varieties, among which are shiny black (OB-4, Figure 2B), shiny reddish-black (OB-5), translucent gray (OB-1, Figure 2A), and opaque gray (OB-3, Figure 2C). The cherts and silicious rocks comprise several types of rocks but are mostly represented by a white chert with abundant vesicles and rough cortex (SR-1, Figure 2C), a white-yellow siliceous rock (SR-5), and a green epidotized silicified rock (SR-3, Figure 2L). They were used to produce retouched flake-tools and artifacts of various kinds such as end-scrapers, side-scrapers and also bifacial projectile points. The tuffs consist mainly of a red dacitic tuff with white crystals (TF-3, Figure 2E), a gray-cream silicified tuff with black inclusions (TF-7, Figure 2F), a brown andesitic tuff (TF-1, Figure 2m), a greenish brown dacitic tuff (TF-4, Figure 2G), and a devitrified cineritic tuff (TF-2, Figure 2H). The andesites are mostly composed of black hornblende andesites with white crystals (AN-1, Figure 2I), and aphiric black andesite (AN-4, Figure 2J). Another commonly present rock is the gray-pink pumice used in the manufacture of probable containers or mortars (Figure 2K).

There are important differences in the frequency of rock classes between sites. In Tuina-5, the predominant rocks are mainly white chert (SR-1), green epidotized siliceous rocks (SR-3) and red dacitic tuffs (TF-3) (Figure 3A). Obsidian is very scarce, occurring only in 31 pieces–all of the translucent gray variety (OB-1) with the exception of one shiny black (OB-4) obsidian flake. On the other hand, a greater diversity of rocks can be observed in Tambillo-1 (Figure 3B): obsidians are abundant, with shiny black (OB-4), translucent gray (OB-1), and opaque gray (OB-3) types predominating. Several varieties of chert, greenish ash tuff (TF-4), brown andesitic tuff (TF-1), and black hornblende andesite (AN-1), among others, were also recorded. Pumice artifacts, granitic rocks, and porphyries are present to a lesser extent. In Tulán-67, devitrified cineritic tuff (TF-2) and chert of the white-yellow (SR-5) variety predominate; there is also a significant frequency of aphiric black andesite (AN-4) and obsidian, particularly the opaque gray variety (OB-3) (Figure 3C).

The directed surveys carried out based on geological and archaeological information have allowed us to document 10 lithic raw material procurement sources so far. Among the sources identified, various volcanic geoforms were distinguished: lava flows (Loma Negra-Puripica), volcanic domes and craters (Jarellón-Laguna Blanca and possibly Machuca-Pelún), maars (Cerro Tujle), ignimbrite flows (Quebrada Zapar and Ignimbrites of Filo Delgado), possible hydrothermal deposits (Salar de Talabre-14 and -18) as well as outcrops of continental sequences exposed in hilltops (Cerros de Tuina and Tulán Cerros). Table 3 summarizes the lithic sources and their main characteristics. In all of them, we recorded evidence of primary processing in the form of cores, test blocks, abundant flakes, blades, and in some cases, stone-hammers and retouched tools. Some of them, such as Loma Negra, Cerros de Tuina, Tulán Cerros, and Cerro Tujle, are large quarry-workshop sites formed by extensive anthropic floors of continuous lithic material.

By comparing the archaeological artifacts with the raw material samples taken in the field we were able to assign the procurement sources. Table 4 summarizes raw material assignments based on the recognition of the lithological markers defined in the geological samples. Figure 12 shows the appearance of each variety at 50x. The shiny black obsidian (OB-4, Figure 12A) and reddish-black variety (OB-5, Figure 12B) was assigned to the Salar de Tara and Jarellón-Laguna Blanca sources, although it is impossible to separate them as they have the same geochemical signature and an identical visual appearance under the microscope. Together with the Zapaleri source (Yacobaccio et al., 2004), Jarellón-Laguna Blanca and Salar de Tara would form a homogeneous group of obsidian sources related to the same magmatic system (Seelenfreund et al., 2010a). In the case of Machuca-Pelún obsidian, two main sub-varieties were distinguished: OB-1 (Figure 12C) and OB-2 (Figure 12D) while the aphiric black andesite (AN-4, Figure 12E) corresponds to the Cerro Tujle maar. The devitrified cineritic tuff (TF-2, Figure 12F) in its three varieties (brown, light brown, and green) corresponds to the Tulán Cerros source complex. The green epidotized silicified rocks (SR-3) come primarily from the Tuina-9 source (Figure 12G), as does the brown andesitic tuff (TF-1, Figure 12H). The gray-cream silicified tuff (TF-7, Figure 12I) corresponds to the source of Talabre-29, 30. Among the wide variety of cherts, a good part of the white chert (SR1-1, Figure 12J) could be assigned to the Talabre-14 and 18 sources. The pumice, recorded in the Tambillo-1 site, was easily assigned to the Zapar source (Figure 12K) and the black hornblende andesites (AN-1, Figure 12L) are related to the Loma Negra-Puripica source.

Some lithic raw materials from unknown sources can be attributed to a local origin. The source of the opaque gray obsidian (OB-3, Figure 13A), recognized by its high content of hornblende and biotite, could be found near the Tulán ravine due to its higher frequency in Tulán sites. We also suspect that the black-red shiny obsidian (OB-6) with large grey amygdales (Figure 13B) comes from the Lascar volcano area (see Figure 1). Other obsidian pieces come from allochthonous sources in northwestern Argentina, as confirmed by XRF and NAA analyses (Loyola, 2020). The translucent obsidian (OB-8) shows reddish oxidized biotite crystals with a hexagonal shape (0.1–0.3 mm) that match with Salar del Hombre Muerto source (Figure 13C); while Ona-Las Cuevas obsidian presents characteristic fluid inclusions with biotite and oxidation (Figure 12D) and tabular hornblende crystals (Figure 12E) that match with our OB-7. Some few pieces of translucent obsidian with black inclusions (OB-9) of developed tabular hornblende (Figure 12F) come from the Alto Tocomar source in Salta, Argentina (see Yacobaccio et al., 2004). Two varieties of siliceous rocks–brown with reddish spots (SR-6, Figure 12G) and white with spots with dendritic habit (SR-4, Figure 13H) – were reported that would come from north of the Imilac basin (Cartajena et al., 2014; Loyola et al., 2019b). The source of the red dacitic tuff with white crystals (TF-3, Figure 13I) is also unidentified, but judging by its frequency it could be available at different points of the eastern border of the Atacama basin; it is most frequently found in archaeological sites near Tambillo and Aguas Blancas ravine (see Figure 1). The white-yellow siliceous rock (SR-5, Figure 13J) could come from a source located 5 km south of Tulán (Yacobaccio and Núñez, 1991). The pink tuff (TF-6, Figure 13K) is less abundant but probably comes from Cerros de CAS as well as a part of the gray basalt (Le Paige, 1970, see Figure 1). A common variety is a dark andesite with tabular hornblende crystals (AN-6, Figure 13L), the source of which is still unknown but presumably local. Finally, comparisons with museum collections make us think that the greenish brown dacitic tuff (TF-4) would come from the Lomas de Ghatchi (Le Paige, 1960; Le Paige 1963; Le Paige 1964) while the black pyroxene andesite (AN-3) is frequent in the quarry-workshops of Valle Chico ravine (Le Paige and Serracino 1974) (see Figure 1).

Analysis of the archaeological assemblages of Tuina-5, Tambillo-1, and Tulán-67 revealed that during the Early Archaic period, stone tools and other lithic objects were made from a wide variety of lithic raw materials of volcanic and subvolcanic origin. Such variability accounts for the use of rocks with different properties and qualities, from the sharpest and best quality, such as obsidian and siliceous rocks, to the most tenacious and resistant, such as andesite, tuffs and basalts, and even others as granite and pumice. Each of these rock classes seems to have been intended for particular categories of tools and objects, production of which required the application of specific know-how and knapping techniques, depending on its particular properties (see Nami, 2015).

However, several factors hindered lithological classification. One of them is the thermal alteration that introduces a series of physical-chemical changes in the artifacts that inhibit their identification, such as luster, rubefaction, calcination, cracking, plotids, and thermal fractures. Heat treatment is a technique widely used in prehistory to improve the quality of knappable rocks through controlled exposure to fire. However, thermal alterations can also result from accidental exposure to fire-pits or natural fires (Inizan and Tixier, 2000). In the sites, thermal alteration of lithic assemblages reaches 1,91% in Tambillo-1 (n=93), 0,82% (n=16) in Tuina-5 and 7,47% (n=247) in Tulán-67. Moreover, it is impossible at present to be sure whether this alteration is due to an intentional process to improve the quality of the raw material or is the involuntary result of exposure to heat sources, such as the several hearths documented at the sites. Further study is needed to explore how thermal alterations expressed in each of the raw materials. On the other hand, assignment was also limited by the high fragmentation or small size of the samples: in some cases, the maximum length of the artifacts analyzed, such as pressure-retouching flakes, was no more than a few millimeters, preventing the conservation of lithic markers and other diagnostic features such as the cortex.

This high diversity of lithic raw materials probably reflects deep knowledge not only of the volcanic landscape and its rocks, but also the techniques necessary to work them. The exploitation of lithic resources among hunter-gatherers in the Atacama basin and adjacent basins has been addressed in various works (Le Paige, 1970; Serracino, 1975; Núñez et al., 2002; Loyola et al., 2021, among others). Judging by the descriptions and the availability of raw materials in the landscape, volcanic rocks have been a constant in Andean hunter-gatherer societies due to their wide availability and easy access, especially in high-altitude environments where their use persisted in later periods. The data obtained in this work suggest that human groups early integrated these resources into their social, economic, and technological sphere, developing a deep knowledge of their properties and characteristics. The application of technological and functional studies currently in progress will offer better understanding of raw material management, production techniques, and contexts of use.

The procurement sources identified offer a first approach to the accessibility and availability of lithic resources in the Atacama basin. Several of these sources had been detected and characterized in different works dating back to the 1960s (Lanning, 1967; Lanning, 1968; Le Paige, 1970; Le Paige and Serracino, 1974; Núñez, 1983; Seelenfreund et al., 2010a; Seelenfreund et al., 2010b; Loyola et al., 2016); however, these works pursued other objectives and used different methodologies. Lithic studies of archaic sites have focused instead on understanding the technological management of resources and mobility patterns at site scale; we have little knowledge about sources of provenance. Conversely, there are several geochemical analyses and field characterizations in the case of obsidian (Seelenfreund et al., 2010a; Seelenfreund et al., 2010b) but with little application to early periods.

Our field surveys identified several lithic sources in the Atacama basin distributed in a vast and contrasting landscape ranging from 2000 to 4,500 m a.s.l. The sources detected are almost entirely volcanic and subvolcanic formations, such as lava flows, maars, craters, caldera-domes, ignimbrite flows, hydrothermal deposits, and outcrops of volcanic facies formed in different geological epochs. Each of them provides various kinds of rock. We documented large quarry-workshop sites in several of these places, with knapping evidence indicating intense and repeated human activity over several periods. The Loma-Negra and Puripica quarry-workshops are extensive areas of discarded material forming a continuous floor of lithic material, including stone structures. In Tulán Cerros, engraved plaquettes and blades have been recorded at the quarry-workshop sites; these provide evidence of symbolic practices (Figures 14A,B), although their chronology has not yet been well specified. Another exceptional engraved volcanic tuff was recovered from the initial occupation floor of Puripica-1 dated to 4,815 + 70 BP (5,651–5,320 cal BP) (Figure 14C), with one of the first manifestations of rock art in the area (Núñez, 1981; Núñez, 1983). The quarry-workshops of the Salar de Talabre are of medium intensity, but with an intense deposition of lithic materials. A similar pattern is found at Cerro Tujle, where the knapping activities were organized around the crater. The absence of evidence of exploitation in the Machuca-Pelún, Salar de Tara and Jarellón-Laguna Blanca sources is probably due to the greater dispersion of the raw material and to the fact that the nodules were collected and transported directly after being tested. Something similar could have happened in the case of the pumices that did not leave observable evidence of production.

The volcanic landscape of the Andean Puna provides a rich and diverse supply of lithic raw materials; however, these rocks are differentially available from limited sources, scattered throughout an arid and mountainous landscape. Human groups quickly integrated volcanic formations and their distribution into their cognitive maps; the archaeological evidence indicates that the sources were stable and recurrent nodes within the seasonal mobility cycle. These were not only spaces where hunter-gatherers carried out extractive activities, but were also occasions for social interaction and transmission of technical knowledge. Among early hunter-gatherers, obsidian appears to have been one of the most appreciated raw materials. The wide availability and distribution of obsidian allowed human groups to provision directly, both during their seasonal occupation of the highlands and from secondary sources on lower floors. This behavior persisted in societies that adopted agro-pastoralist ways of life in later periods. Thus, obsidian and other rocks continued to circulate and be exchanged over great distances (Berenguer, 2004; Yacobaccio, et al., 2004; Núñez, et al., 2007; Escola et al., 2016; Loyola et al., 2021).

By comparing the archaeological assemblages with samples collected in the field, potential sources of origin could be assigned to the lithic raw materials. This allows us to track the circulation of raw material between different microenvironments such as the Domeyko mountain range, the Precordillera foothills, the Altiplano, and even the eastern slope of the Andes. After a first evaluation, it can be suggested that the frequency of each raw material in the assemblages is directly related to the distance from its source. The lithic landscape, understood as the physical distribution and availability of rock resources (Gould and Saggers, 1985), offers a wide diversity of resources over variable distances. Most of the lithic raw materials come from sources in the immediate surroundings of the sites, whereas raw materials from more distant sources are transported to the settlements in smaller amounts and volumes. This differential distribution of raw materials can be directly related to the techno-economic zoning of the landscape. Sources in the immediate surroundings of the sites (<5 km) could be exploited as part of daily activities within the foraging area. The redundancy and intensity of activities in these spaces allowed the formation of large quarry-workshop sites such as Loma Negra, Tulán Cerros, and Cerros de Tuina. On the other hand, raw materials from more distant local sources (5–40 km), had to be supplied through other mechanisms; for example, through inter-settlement transport, within the seasonal mobility circuit, or even through specific logistical trips, leaving little evidence in situ, as is the case of Machuca-Pelún and Salar de Tara and Jarellón-Laguna Blanca. Rocks of allochthonous origin, especially trans-Andean obsidian, may have been obtained in smaller volumes by exchange or some other type of long-distance interaction.

The relationship between past societies and volcanism has generally been approached through the risk and impact of eruptive events (Torrence et al., 2000; Grattan et al., 2002; Shimoyama, 2002; Torrence and Grattan, 2002; Vanderhoek and Nelson, 2007; Torrence, 2014). In the Andes, a correlation between cultural changes and volcanic explosions in recent periods has been suggested (Bouysse-Cassagne and Bouysse, 1984; Pärssinen, 2015); however, we know little about early hunter-gatherer societies (Grosjean et al., 2007). Some works have discussed the consequences of volcanic events during the demographic bottleneck of the Middle Holocene period (Durán and Mikkan, 2009), and their effects on interaction networks and social organization (Aschero, 2016). Several catastrophic events and eruptions have occurred during the long sequence of human occupation in the Atacama Basin; in fact, volcanic ash layers interspersed with human occupations have been reported in Tulán-109 (2,900 m a.s.l) (Figure 14D), San Lorenzo-1 (3,000 m a.s.l), Tuina- 1 and -3 (3,000 m a.s.l), Miscanti-1 (4,200 m a.s.l) and Tambillo-6 (2000 m a.s.l), among others (Núñez et al., 2005; Núñez et al., 2018) but they have not yet been adequately studied. The Tulán-54 site, one of the oldest ceremonial centers in the region, was built on a dense layer of volcanic ash (Núñez et al., 2017). Local geological research has reported large-scale eruptions that could have formed the ash layers at archaeological sites. This is the case of the Tumbres eruption (9,100–9,300 cal BP), which produced an andesitic pumice fall deposit and a pyroclastic flow that extended for more than 10 km (Gardeweg et al., 1998). Likewise the Socompa devastating eruption (6,051 m a.s.l) produced a massive debris avalanche (7,200–6,200 cal BP) that extended for 40–50 km (van Wyk de Vries et al., 2001; Davies et al., 2010) with an ash fall area whose extent is still unknown. In the Argentine northwest, several Pleistocene and Holocene volcanic ash deposits have been reported, in some cases more than 4 meters thick (Fernández-Turiel et al., 2012).

These events must have occurred contemporaneously, and must have impacted early human societies not only through their direct consequences. Records of eruptions can persist for centuries in collective memory and oral tradition in the form of myths (Fox Hodgson, 2007). However, it has been argued that hunter-gatherer societies have a greater degree of resilience and tend to recover quickly from the sudden stress of explosive eruptions (Sheets 1999; Sheets, 2001). Volcanoes seem rather to have been recurrent nodes of interaction and mobility within the mobility cycle, and sources of raw materials from which to manufacture objects–not only tools for subsistence but also goods with a social and symbolic value, as in the case of rock art on ignimbrite formations (Núñez et al., 2017); obsidian projectile points were exchanged over great distances and deposited as offerings in ceremonies among late hunter-gatherers and early pastoralist groups (Loyola et al., 2020). Considering the continuity in the exploitation of these sources in later periods, knowledge of the landscape and its rocks must have been stored in oral tradition and shared cognitive maps in the long-term. It is therefore reasonable to suppose that this same knowledge probably laid the foundations for the development of the copper mining and lapidary technologies, for which the societies of the Atacama were widely recognized until recent times (Figueroa et al., 2013; Sapiains et al., 2022).