Browsing by Author "Nuevo-Delaunay, Amalia"

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    Bioavailable Strontium, Human Paleogeography, and Migrations in the Southern Andes: A Machine Learning and GIS Approach
    (2021) Barberena, Ramiro; Cardillo, Marcelo; Lucero, Gustavo; le Roux, Petrus J.; Tessone, Augusto; Llano, Carina; Gasco, Alejandra; Marsh, Erik J.; Nuevo-Delaunay, Amalia; Novellino, Paula; Frigole, Cecilia; Winocur, Diego; Benitez, Anahi; Cornejo, Luis; Falabella, Fernanda; Sanhueza, Lorena; Santana Sagredo, Francisca; Troncoso, Andres; Cortegoso, Valeria; Duran, Victor A.; Mendez, Cesar
    The Andes are a unique geological and biogeographic feature of South America. From the perspective of human geography, this mountain range provides ready access to highly diverse altitudinally arranged ecosystems. The combination of a geologically and ecologically diverse landscape provides an exceptional context to explore the potential of strontium isotopes to track the movements of people and the conveyance of material culture. Here we develop an isotopic landscape of bioavailable strontium (87Sr/86Sr) that is applied to reconstruct human paleogeography across time in the southern Andes of Argentina and Chile (31 degrees-34 degrees S). These results come from a macro-regional sampling of rodents (N = 65) and plants (N = 26) from modern and archeological contexts. This "Southern Andean Strontium Transect" extends over 350 km across the Andes, encompassing the main geological provinces between the Pacific coast (Chile) and the eastern lowlands (Argentina). We follow a recently developed approach to isoscape construction based on Random Forest regression and GIS analysis. Our results suggest that bioavailable strontium is tightly linked with bedrock geology and offers a highly resolved proxy to track human paleogeography involving the levels of territories or daily mobility and anomalous events that disrupt home ranges, such as migration. The southern Andes provide an ideal geological setting to develop this approach, since the geological variation in rock age and composition produces distinctive isotopic signatures for each main biogeographical region. Finally, we apply this framework to a set of results from human remains from the Uspallata Valley in Mendoza (Argentina), to assess the incidence of migration in the key period of the consolidation of agropastoral economies between AD 800 and 1400. The application of the isoscape to the values from human remains confirms the persistence of human groups with relatively restricted territories encompassing Uspallata and the adjacent Precordillera between AD 800 and 1500. We also identify a pulse of human migration between AD 1280 and 1420, shortly preceding the Inka conquest. Looking forward, we expect to converge with ongoing efforts in South America to build a continental research framework to track the movement of people, animals, and artifacts across space and time.
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    Middle through late Holocene long-distance transport of exotic shell personal adornments in Central West Patagonia (southern South America). The archaeomalacological assemblage of Bano Nuevo 1
    (2024) Hammond, Heidi; Zilio, Leandro; Nuevo-Delaunay, Amalia; Mendez, Cesar
    The exchange of information and social interactions on broad spatial scales between human groups in the past can be studied through the provenance of key indicators of distant origin recorded at archaeological sites. The remains of shells of mollusk species, especially when crafted as elements of personal ornaments, express aspects of the behaviors and valuations for the populations that selected, transformed, and exchanged such items. In the southern cone of South America, past hunter-gatherer groups traveled long distances and interacted with communities distributed throughout the territory to acquire goods for technological use, visual display or considered highly valued materials. When recorded at distant locations, these goods of extra local origin are very informative regarding the differences between commonly used home ranges and the occasional access to remote spaces. We present the results of the analysis of the archaeomalacological assemblage of the Bano Nuevo 1 site, a cave with exceptional preservation conditions in Central West Patagonia. This site has yielded a diverse group of artifacts made of shells with origins from multiple distances, as well as evidence of the use of marine, freshwater, and terrestrial species. Its deposits, which extend over the last 11,000 years, reveal an antiquity of at least the middle Holocene for the acquisition, manufacture, use and transport of goods as personal ornaments from shells in the macroregion.
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    Postglacial landscape dynamics and fire regimes in west Central Patagonia, Chile (44°S, 72°W): Evidence from the Cisnes River Basin
    (2024) Alvarez-Barra, Valentina; Maldonado, Antonio; de Porras, Maria Eugenia; Nuevo-Delaunay, Amalia; Mendez, Cesar
    We examine the long-term changes in vegetation structure and wildfires regimes in the Chilean Patagonia (44 degrees S, 72 degrees W) at the westernmost part of the Cisnes River basin. Previous studies within this basin have accounted for millennial shifts in glacier, vegetation and fire dynamics but at its easternmost portion. Here, we present a pollen a macro-charcoal particles record from Laguna Las Mellizas del R & iacute;o Cisnes (LLMRC; 44 degrees 38'48.13"S; 72 degrees 19'42.58"W; 209 m a.s.l.) that encompasses the last 13,900 cal yr BP. After glacier retreat, the LLMRC record shows incipient plant colonization upon the retreat of the ice caps (13,900-12,400 cal yr BP), inferred by the low PAR values (< 500 grains cm (-2) yr (-1)) and negligible fire activity. The end of the Lateglacial period is characterized by increased values of N. dombeyi-type and the mistletoe Misodendrum, with the coeval presence of Podocarpus nubigenus and Pilgerodendron uviferum suggesting humid and warm conditions since 12,400 cal yr BP. A peak in Weinmannia trichosperma percentages (similar to 56%) marks the Holocene onset in the LLMRC record indicating a shift towards warmer conditions and enhanced rainfall seasonality, coupled with enhanced fire activity between 11,700 and 9000 cal yr BP. Increased moisture conditions after 9000 cal yr BP trigger the development of a closed Nothofagus-Podocarpus forest while the establishment of the North Patagonian rainforest occured during the middle Holocene (similar to 8000 cal yr BP). The LLMRC record indicate a shift towards an open forest and moderate fire activity during the late Holocene. Despite the documented presence of indigenous population in the region, the results suggest no influence of human activity as potential triggers for fires in this record for the last 4000 years. Overall, the results of LLMRC record suggest the paramount importance of the Southern Westerlies in modulating the observed shifts in vegetation structure and wildfires at the westernmost portion of the Cisnes River basin.