South-central Andes Research Articles

Andean Landscape Legacies: Comprehensive Remote Sensing Mapping and GIS Analysis of Long-Term Settlement and Land Use for Sustainable Futures (NW Argentina)

The Andes region has an exceptional record of high-altitude settlements integrated within widespread regional chains of mobility and exchange. The Sierra de Aconquija (NW Argentina, south-central Andes) is an effective climatic barrier that has afforded an enduring indigenous approach to land use, mobility, and exchange over millennia. Despite this rich history, the Sierra has been largely considered marginal in pre-Columbian regional cultural developments. Today, the expansion of extractive industries threatens the region’s heritage and the sustainable futures of local communities. Innovative, integrative methodologies are needed for landscape characterisation, heritage assessment, and sustainable policy development. Building on earlier work, we undertook the first comprehensive mapping of archaeological features over 3800 sq. km of the Sierra using interpreter-led assessment of commercial and open-access satellite imagery and DSM data, to verify earlier assumptions and to identify previously unnoticed trends in the aggregation, distribution, and connectivity of archaeological features. The mapping identified 6794 features distributed unevenly but with clear tendencies towards maximising topographic, ecologic, and connectivity advantages expressed consistently across the study area. The outcomes confirm the important role the Sierra had in pre-Hispanic times, highlighting the significance of ancient indigenous practices for the sustainability of vulnerable upland landscapes both in the Andes and worldwide.

Migration scale, process, and impact in the Tiwanaku colonies: Paleomobility at the archaeological site of Omo M10.

Contemporary migrations show form and intensity of interaction between homeland and host communities to shape social dynamics and identities. We apply here a contemporary theoretical framework and biogeochemical analyses to elucidate the scale, processes, and impacts of migration in the Tiwanaku polity (6th-11th c. CE) by inferring the mobility of individuals interred at the Tiwanaku-affiliated site of Omo M10 (Moquegua Valley, Peru). For each of 124 individuals, we captured paleomobility across the life-course by analyzing up to four enamel and bone samples that formed during discrete developmental periods for radiogenic strontium (87Sr/86Sr) and stable oxygen (δ18Ocarbonate(VPDB)) isotopes. At Omo M10, archaeological human enamel and bone values range from 87Sr/86Sr = 0.70632-0.72183 and δ18Ocarbonate(VPDB) = -13.4‰ to +1.7‰, with a mean of 87Sr/86Sr = 0.70763 ± 0.00164 (1σ, n = 334) and δ18O = -7.8‰ ± 1.9‰ (1σ, n = 334). Together with archaeological evidence, we interpret these data as evidence for multigenerational interaction between communities in the high-altitude Tiwanaku heartland and at the site of Omo M10. Our results suggest that one-fourth of individuals spent some part of their life outside of Moquegua and one in eight individuals from Omo M10 were first-generation migrants. Greater mobility of females and juveniles at Omo M10 indicates that gender and family were important social constructs in maintaining relationships and cultural continuity in provincial Tiwanaku life, and communities maintained autochthonous migration streams with Tiwanaku-affiliated populations throughout the south-central Andes. Intra-individual biogeochemical analyses of migration at Omo M10 contribute a nuanced perspective on the diverse experiences of multigenerational Tiwanaku colonies.

ORIGIN OF VOLCANIC-HOSTED MAGNETITE AT THE LAGUNA DEL MAULE COMPLEX, CHILE: A NEW EXAMPLE OF ANDEAN IRON OXIDE-APATITE MINERALIZATION

Abstract Iron oxide-apatite (IOA) deposits, also known as magnetite-apatite or Kiruna-type deposits, are a major source of iron and potentially of rare earth elements and phosphorus. To date, the youngest representative of this group is the Pleistocene (~2 Ma) El Laco deposit, located in the Andean Cordillera of northern Chile. El Laco is considered a unique type of IOA deposit because of its young age and its volcanic-like features. Here we report the occurrence of similarly young IOA-type mineralization hosted within the Laguna del Maule Volcanic Complex, an unusually large and recent silicic volcanic system in the south-central Andes. We combined field observations and aerial drone images with detailed petrographic observations, electron microprobe analysis (EMPA), and 40Ar/39Ar dating to characterize the magnetite mineralization—named here “Vetas del Maule”—hosted within andesites of the now extinct La Zorra volcano (40Ar/39Ar plateau age of 1.013 ± 0.028 Ma). Five different styles of magnetite mineralization were identified: (1) massive magnetite, (2) pyroxene-actinolite-magnetite veins, (3) magnetite hydrothermal breccias, (4) disseminated magnetite, and (5) pyroxene-actinolite veins with minor magnetite. Field observations and aerial drone imaging, coupled with microtextural and microanalytical data, suggest a predominantly hydrothermal origin for the different types of mineralization. 40Ar/39Ar incremental heating of phlogopite associated with the magnetite mineralization yielded a plateau age of 873.6 ± 30.3 ka, confirming that the emplacement of Vetas del Maule postdated that of the host andesite rocks. Our data support the hypothesis that the magnetite mineralization formed in a volcanic setting from Fe-rich fluids exsolved from a magma at depth. Ultimately, Vetas del Maule provides evidence that volcanic-related IOA mineralization may be more common than previously thought, opening new opportunities of research and exploration for this ore deposit type in active volcanic arcs.

Lugares propios en territorios comunes

I analyze the practices related to home-making among llama pastoralists in the South-Central Andes, a process which is understood as a continuous negotiation among different kinds of persons, both human and nonhuman. I start by conceptualizing pastoralism as a social interaction network involving herders, their animals, the community (as the owner of the land), and various deities. Then, I analyze how llameros negotiate the placement of the house with each one of these agents, according to a logic that is explicitly manifested in ritual. In order to illustrate this point, I describe the k’illpa or «flowering» of the animals, the main domestic ritual of the annual cycle. I put emphasis on the ritual gestures and the way in which they express and reproduce this social fabric which defines the place of each family in the territory and in the world.

Lugares propios en territorios comunes

I analyze the practices related to home-making among llama pastoralists in the South-Central Andes, a process which is understood as a continuous negotiation among different kinds of persons, both human and nonhuman. I start by conceptualizing pastoralism as a social interaction network involving herders, their animals, the community (as the owner of the land), and various deities. Then, I analyze how llameros negotiate the placement of the house with each one of these agents, according to a logic that is explicitly manifested in ritual. In order to illustrate this point, I describe the k’illpa or «flowering» of the animals, the main domestic ritual of the annual cycle. I put emphasis on the ritual gestures and the way in which they express and reproduce this social fabric which defines the place of each family in the territory and in the world.

Kinematic modeling of neotectonic thrusts at the Andean orogenic front (southern Precordillera, Argentina)

The south-central Andes located between 32°-33° S are considered to be a transitional zone between the flat-lying and the normal subduction zones of the Nazca Plate. The active mountain-building processes are mainly concentrated between the Andean eastern foothills and the adjacent broken foreland, as highlighted by crustal seismicity, historic destructive earthquakes, and Quaternary-active contractional structures. Between 32° 10′ and 32° 40′ S, the Andean orogenic front is exposed at the Las Peñas-Las Higueras range, where east- and west-verging thrusts interact, resulting in an antithetic linkage transfer zone. We built kinematically-balanced structural sections through the integration of surface and subsurface data (2D seismic lines) to achieve a 3D characterization of the Quaternary-active thrusts and to estimate shortening rates of ∼1.8–3.4 mm/a during the last ∼8.5 Ma, thus extending the spatial and temporal penetration achieved by surface geology data. Our results indicate that the main east-verging thrusts detach at a depth of ∼10 km within Paleozoic basement rocks. This outcome implies larger potential rupture areas than if rooted at Neogene layers. West-verging thrusts present detachment levels at ∼5 km, also linked to Paleozoic basement rocks. The analysis of 2D seismic lines has also contributed to the recognition of blind thrusts without a morphologic signature, which could be regarded as relevant seismogenic structures.

Obsidian Procurement and Exchange at the Apogee of Empire: Wari Political Economy in Arequipa, Peru

AbstractDuring the Middle Horizon (AD 600–1000), obsidian was transported in greater quantities and distances than ever before identified in the Andes, in part by the expansionary Wari state. Two of the three major obsidian sources used in the south-central Andes are located in the modern department of Arequipa, Peru. Arequipa was a region of intense Wari influence and intrusive presence; however, little is known about regional obsidian use. Portable X-ray fluorescence (pXRF) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used to analyze 383 obsidian artifacts recovered from 10 archaeological sites in Arequipa. Results highlight diachronic and spatial patterning related to obsidian procurement strategies, state versus bottom-up exchange networks, and local participation within the Wari realm. A wide variety of geological obsidian sources, including nonlocal obsidians originating from Wari's Ayacucho heartland, were used. By the late Middle Horizon, the Wari had consolidated regional resources with the sole use of Alca-1 and Alca-4 bedrock obsidians, the largest-sized and highest-quality sources in the area. We assess related models of obsidian procurement and exchange related to state political economy, long-distance caravan activity, and the role of local ceremonial/waystation centers that facilitated the flow of ideas, goods, and people across Arequipa.

Diet breadth and biodiversity in the pre-hispanic South-Central Andes (Western South America) during the Holocene: An exploratory analysis and review

This paper presents an exploratory study on the taxonomic diversity of pre-Hispanic archaeofaunas in the South-Central Andes (SCA; western South America) from the Pleistocene-Holocene boundary to the Late-Holocene. The SCA is a complex of diverse environments and has undergone distinct climate events for the last 13,000 years, such as the occurrence of warmer and drier conditions in the Middle-Holocene. The South-Central Andean area was part of the larger Andes interaction area, which was a primary center for animal and plant domestication and the emergence of agro-pastoralist economies. Since subsistence was key to these processes, the SCA provides a relevant case study on the interactions among environment, foodways and sociocultural evolution. Taxonomic diversity was used here as a proxy for diet breadth. A total of 268 archaeofaunal assemblages were sampled from the zooarchaeological literature. Reviewed variables included the cultural chronology and spatial coordinates of the assemblages, as well as the presence and abundance of taxa at the family rank. Taxonomic diversity covered two dimensions: composition (families present in each assemblage) and structure (quantitative relationships among taxa), which was measured through richness (NTAXA), ubiquity and relative abundance (NISP based rank-order). Despite the uneven distribution of samples, the analyses revealed the following trends: (1) a moderate relationship between NTAXA and distance from coastline for most of the Holocene; (2) a potential decrease in assemblage richness for coastal ecoregions during the Late-Holocene; and (3) a generalized increase in the relative abundance of Camelidae.

Metaphoric veiled image-schema of kinship organization in ceremonial space: A south Andean case

This study is an interdisciplinary approach to a veiled metaphoric design expressed in the present-day spatial layout of ecologically-derived patronyms of Mapuche lineages and families positioned in public ceremonial plazas. The perspective combines ethnoarchaeological, cognitive, iconographic, oral tradition, allegoric metaphor, and historical approaches to the organization and meaning of this design, taking into account the past and present dimensions of ritual media (e.g., political, ideological and sensorial) to render a concept publicly graspable. Shamans and other informants state that the design represents an ancient foundational schema established for intercommunity political solidarity during times of both peace and conflict in the Spanish colonial and Republican era of the south-central Andes of Chile. Shamans were asked to draw their mental image of the hidden design of the plaza to pictographically reveal its visual representation. By examining the iconography of patronyms depicting a loosely structured order of families hierarchically positioned in ceremonial space, the invisible nature of this pattern and its wider political and kinship meaning is considered. Viewed from an archaeological perspective, this schema is suggested to be associated with a “chiefdom” or intermediate, polity-level society, and may represent a type of mental imagery and template that served as a precursor to the visible iconography on wood, stone, adobe, ceramic, textile and other media of complex Pre-Colombian societies. Ultimately, this schema is a conceptual metaphor: mapping and structuring knowledge of a trophic hierarchy of elements in the natural world to evoke a political and public organizational principle through sensorial experiences and life concerns in the invisible and visible domains of an Andean-like ceremonial format.

New Methodologies for a Latin American Economic History on the 19th Century: The South-Central Andes

The economic literature of nineteenth-century Latin America has been dominated by its focus on the import-export complex and by comparisons with the United States and Western Europe, discussing why Latin America did not develop like the former regions. The use of import-export data is deficient in un- derstanding economic development of the region; comparisons about what Latin America is not does not help understanding how development occurred. Instead, the essay develops new concepts such as the internal economy, as well as methodologies and categories to analyze the changes in the Latin American economy from 1830 to 1920, using as a case study the south-central Andes.

New Methodologies for a Latin American Economic History on the 19th Century: The South-Central Andes

The economic literature of nineteenth-century Latin America has been dominated by its focus on the import-export complex and by comparisons with the United States and Western Europe, discussing why Latin America did not develop like the former regions. The use of import-export data is deficient in un- derstanding economic development of the region; comparisons about what Latin America is not does not help understanding how development occurred. Instead, the essay develops new concepts such as the internal economy, as well as methodologies and categories to analyze the changes in the Latin American economy from 1830 to 1920, using as a case study the south-central Andes.

Homeland Food Traditions in the Tiwanaku Colonies: Quinoa and Amaranthaceae Cultivation in the Middle Horizon (AD 600–1100) Locumba Valley, Peru

Abstract The Tiwanaku civilization (around AD 500–1100) originated in the Bolivian altiplano of the south-central Andes and established agrarian colonies (AD 600–1100) in the Peruvian coastal valleys. Current dietary investigations at Tiwanaku colonial sites focus on maize, a coastal valley cultivar with ritual and political significance. Here, we examine Tiwanaku provincial foodways and ask to what degree the Tiwanaku settlers maintained their culinary and agrarian traditions as they migrated into the lower-altitude coastal valleys to farm the land. We analyze archaeobotanical remains from the Tiwanaku site of Cerro San Antonio (600 m asl) in the Locumba Valley and compare them to data from the Tiwanaku site in the altiplano and the Rio Muerto site in the Moquegua Valley during the period of state expansion. Our findings show high proportions of wild, weedy, and domesticated Amaranthaceae cultivars, suggesting that Tiwanaku colonists grew traditional high-valley (2,000–3,000 m asl) and altiplano (3,000–4,000 m asl) foods on the lowland frontier because of their established cultural dietary preferences and Amaranthaceae's ability to adapt to various agroclimatic and edaphic conditions.

The Late Intermediate Period in the south-central Andes (AD 1000–1450): Key problems in chronology

The Late Intermediate Period (LIP, cal AD 1000–1450) in the central Andes is defined as a hiatus after the collapse of Tiwanaku and Wari, expansive state polities of the Middle Horizon (cal AD 600–1000), and before the domination of the Inca empire in the Late Horizon (cal AD 1450–1532). The LIP is often characterized as a unit, but major developments took place within this long period, including diasporic migrations and the new colonization of some regions, demographic change, intensified conflict, large-scale adverse climate episodes, and changes associated with the onset of Inca expansion. Here we make a preliminary attempt to clarify the chronology of these developments. A database of published and new radiocarbon dates is compiled for the south-central highlands and coastal valleys in order to model overall and subregional demographic trends using an updated “dates-as-data” cumulative kernel density estimate (CKDE) approach, and to examine specific LIP phenomena in two subregions. Our results indicate major demographic change including 1) substantial population growth beginning in the 13th century, 2) a marked 14th-century population surge in most, but not all, subregions included here, 3) evidence of population decline in several subregions during the same intervals when neighboring populations are expanding. Population growth was associated with intensified violence and increased physiological stress in the upper Nasca drainage. In the altiplano of Peru and Bolivia, population growth accompanied the rise of defensive hillforts and monumental cemeteries. Our date models also indicate a more complicated terminal LIP in the altiplano, with the height of classically “LIP” societies overlapping with early evidence for imperial Inca presence. This paper highlights the ways that more refined chronology can make advances in our understanding of a turbulent post-collapse era in the Andes.

Statement of Retraction: Pastoral Paleoclimate Palimpsests of the South-Central Andes: High-Altitude Herder Dwellings in the 2nd Millennium a.d.

Statement of Retraction: Pastoral Paleoclimate Palimpsests of the South-Central Andes: High-Altitude Herder Dwellings in the 2nd Millennium a.d.

Provenance and long-term circulation of archaeological obsidian in the Puna de Copiapó (25-27°S), South-Central Andes

We present obsidian compositional data obtained by X-ray fluorescence analysis in the Andean highlands (25-27°S/68-69°W) of northern Chile. Seventy-six samples (n = 76) from three lithic sources and six archaeological sites were analyzed, covering a chronological sequence from 10,100 to 500 cal BP. Compositional analyses indicate the exploitation of the Ciénaga Redonda and Cerro Manchado local sources as well as Ona-Las Cuevas and Salar del Hombre Muerto located between 200 and 230 km away on the eastern slope of the Andes, in northwestern Argentina. The results obtained show that the Puna de Copiapó has been a key area for circulation between the eastern and western slopes of the Andes since pre-Columbian times.

Spatial analysis of paleoclimate variations based on proxy records in the south-central Andes (18°- 35° S) from 32 to 4 ka

The long-term climate dynamics of the central Andes are part of an ongoing international research effort to reconstruct past climatic variations and sensitivity to different regional and global drivers during the last 50,000 years. The large number of diverse records, however, makes it difficult to compare results without an integrated spatial analysis that considers the nature of the record and whether they are integrating environmental conditions across a large basin (i.e., a lake record) or at a very local scale (such as a rodent midden). We compiled 92 records from the southern sector of the central Andes (SCA, 18°-35°S). Recalibrated records were further compared by converting the original author's interpretation into a scale of relative moisture anomalies (compared to the present) that ranges from −2 (very dry) to very wet (+2). Moisture anomaly maps were generated for intervals at 4, 6, 9.5, 14, 17, 21 and 32 ka BP (103 calibrated 14C years before present) using records within a 5% age uncertainty. Our compilations show a surprising degree of agreement in the extent and magnitude of past climate changes during late Pleistocene, but less spatial agreement during the Holocene. The TRACE21 transient climate model shows similar results, with better agreement during the Pleistocene compared to the Holocene. Our analyses not only reveal discrepancies between proxy record interpretations at sites from the same region but show which regions in the SCA require more study.

Climate aridity delays morphological response of Andean river valleys to tectonic uplift

In the south Central Andes, a complex relationship between climate, tectonics, erosion and topography is well documented. Building on recent advances in the mechanical modelling of subduction zones, we isolate the contribution of fault motion to topography and observe how rock uplift has been recorded in river valley morphology. Rivers on the wetter, western Chilean-side of the Andean cordillera have steep and narrow valleys, in stark contrast to those draining east across the arid Argentinian cordillera, whose valleys are variably wider and less steep. The Chilean rivers have responded to fault slip along the western mountain front by incising vertically and propagating a steepening zone upstream. In Argentina, there is little evidence of channel steepening despite predictions for higher vertical rock uplift rates. We hypothesise that the aridity of the Argentinian region has limited the transport capacity of the rivers to export their sediment fill and as a result, vertical incision has been inhibited and lateral incision and valley widening favoured. The long-term climate gradient appears to have been important in modulating the morphological response of these rivers to fault slip. These factors precondition future landscape sensitivity to both tectonic and climatic change.

Ancient mitochondrial genome diversity in South America: Contributions from Quebrada del Toro, Northwestern Argentina.

The objective of this study was to enhance our understanding of the population history in South America, specifically Northwestern Argentina, by analyzing complete ancient mitogenomes of individuals from the Ojo de Agua archeological site (970 BP) in Quebrada del Toro (Salta, Argentina). We analyzed teeth from four individuals from the site Ojo de Agua (970 ± 60 BP), located in Quebrada del Toro (Andean region of Northwestern Argentina). DNA extracts were converted to double-stranded DNA libraries and indexed using unique dual-indexing primer combinations. DNA libraries were then enriched for the complete mitochondrial genome, pooled at equimolar concentrations, and sequenced on an Illumina® MiSeq™ platform. Reads from high quality libraries were trimmed, merged, and then mapped to the revised Cambridge Reference Sequence. The aDNA damage patterns were assessed and contamination estimated. Finally, variants were called, filtered, and the consensus mitogenome was constructed and used for haplogroup assignment. We also compiled available mitogenome sequences from ancient and present-day populations from the Southcentral Andes and other surrounding regions in Argentina. Maximum Likelihood and Bayesian phylogenetic reconstructions were obtained using the generated dataset. We successfully obtained the complete mitogenome sequence from one individual with an average depth coverage of 102X. We discovered a novel haplotype that was assigned to haplogroup D1. Phylogenetic reconstructions suggests that this haplotype falls within the sister branches of the D1j lineage, forming a well-supported clade. The estimate TMRCA of this clade that includes D1j and its sister branches ranged between 12,535 and 18,669 ya. The sequence analyzed in this study represents the first ancient mitogenome from within the valley region in Northwestern Argentina. We found that a representative of a lineage highly associated with D1j was already present approximately 1000 BP in the region. Our results agree with the proposed origin of D1j in other regions north of Patagonia and independent of the Pacific coast fast migratory route, contrary to what was originally hypothesized. This study highlights the lack of information regarding pre-Hispanic genetic diversity and contributes to the knowledge about the peopling process in South America.

Climate change intensified violence in the south-central Andean highlands from 1.5 to 0.5 ka

AbstractThe archaeology of the pre-contact Andes provides an ideal study of human responses to climate change given the region's extreme climatic variability, excellent archaeological preservation, and robust paleoclimate records. We evaluate the effects of climate change on the frequency of interpersonal violence in the south-central Andes from ca. 1.5–0.5 ka (AD 470–1540) by comparing incidents of skeletal trauma observed among 2753 crania from 58 sites to rates of ice accumulation at the Quelccaya Glacier. We find that, in the highlands, the odds of identifying inter-personal violence increase on average by a multiplicative factor of 2.4 (1.8–3.2; 95% C.I.) for every 10-centimeter decrease in annual ice accumulation. Our statistical analysis does not detect a relationship between ice accumulation and interpersonal violence rates among coastal or mid-elevation populations. This disparity likely resulted from variable economic and sociopolitical strategies at different elevations. The failure of rain-fed agriculture during periods of drought and concomitant dissolution of organizing polities likely predisposed highland populations to socioeconomic stress and violent competition for limited resources. Conversely, diversity among lowland and midland economies may have buffered against the effect of drought.

Hominins and carnivores in the Early Pleistocene site of Barranco León (Orce, Baza Basin, SE Spain): Comment on Courtenay et al. (2023)

This work investigates questions regarding obsidian circulation among the late populations (since ca. 1100 BP) of Antofagasta de Sierra (Catamarca Province, Argentinean Southern Puna Plateau). By means of geochemical provenance studies conducted on obsidian artefacts, the sources of obsidian that these groups accessed have been identified. The samples considered in this study were collected at three radiocarbon-dated sites in the micro-region: La Alumbrera, Bajo del Coypar II and Campo Cortaderas.The results obtained are compared with those available for other contemporary sites and Formative contexts (ca. 3000–1100 BP) within the area of study. A preliminary discussion is presented on the basis of the environmental, political and social tendencies that characterized the times after ca. 1100 BP at the micro-region and south-central Andes.