RESUMO

We present stable hydrogen-isotope analyses of volcanic glass ([Formula: see text]Dg) and radiometric ages (U-Pb zircon, U-Th calcite, AMS14C) from deformed sedimentary deposits in the vicinity of the intermontane Pocitos Basin in the central Puna of the Andean Plateau at about 24.5°S. Our results demonstrate 2-km surface uplift since the middle to late Miocene and protracted shortening that persists until the present day, while other sectors of the Puna show evidence for tectonically neutral and/or extensional settings. These findings are at odds with previous studies suggesting near-modern elevations (4 km) of the Puna Plateau since the late Eocene and formation of the intermontane Miocene Arizaro-Pocitos Basin associated with gravitational foundering of a dense lithosphere. Geophysical and geochemical data support the removal of continental lithosphere beneath the Puna, but the timing and mechanisms by which this removal occurs have remained controversial. We hypothesize that intermontane basin formation in the central Puna is the result of crustal shortening since about 20 Ma, followed by rapid surface uplift, likely related to lithospheric delamination.

RESUMO

OBJECTIVES: The main aim of this work was to contribute to the knowledge of pre-Hispanic genetic variation and population structure among the South-central Andes Area by studying individuals from Quebrada de Humahuaca, North-western (NW) Argentina. MATERIALS AND METHODS: We analyzed 15 autosomal STRs in 19 individuals from several archaeological sites in Quebrada de Humahuaca, belonging to the Regional Developments Period (900-1430 AD). Compiling autosomal, mitochondrial, and Y-chromosome data, we evaluated population structure and differentiation among eight South-central Andean groups from the current territories of NW Argentina and Peru. RESULTS: Autosomal data revealed a structuring of the analyzed populations into two clusters which seemed to represent different temporalities in the Andean pre-Hispanic history: pre-Inca and Inca. All pre-Inca samples fell into the same cluster despite being from the two different territories of NW Argentina and Peru. Also, they were systematically differentiated from the Peruvian Inca group. These results were mostly confirmed by mitochondrial and Y-chromosome analyses. We mainly found a clearly different haplotype composition between clusters. DISCUSSION: Population structure in South America has been mostly studied on current native groups, mainly showing a west-to-east differentiation between the Andean and lowland regions. Here we demonstrated that genetic population differentiation preceded the European contact and might have been more complex than thought, being found within the South-central Andes Area. Moreover, divergence among temporally different populations might be reflecting socio-political changes occurred in the evermore complex pre-Hispanic Andean societies.

Assuntos

DNA Antigo/análise , Indígenas Sul-Americanos/genética , Arqueologia , Feminino , Marcadores Genéticos/genética , Genética Populacional , Humanos , Masculino , Repetições de Microssatélites/genética , Peru , Análise de Sequência de DNA , Dente/química

RESUMO

White virgules, commas, and dot designs on tricolored ceramics are sporadically found in different archaeological sites located in Northwestern Argentina area, as Puna and Quebrada de Humahuaca. This decorating style has been reported in several articles, but few previous archaeometric studies have been carried out on the pigment composition. Fragments from Puna and Quebrada archaeological sites, belonging to Regional Development Period (900-1430 AD), were analyzed by X-ray diffraction and Raman spectroscopy in order to characterize the pigments employed. Red and black pigments are based on iron and manganese oxides, as it has been extensively reported for the NW Argentina area. White pigments from white virgules, comma, and dot designs have shown different composition. Hydroxyapatite was found in samples from Doncellas site (North Puna region), and calcium and calcium-magnesium containing compounds, as vaterite and dolomite, along with titanium containing compounds were detected on samples from Abralaite (Central Puna region) and Gasoducto (Quebrada de Humahuaca region). It has been concluded that pigment composition is not characteristic of a unique region.