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Simple Summary: The Laguna Negra is a high-altitude hypersaline lake located in the Puna region in Argentina, hosting microbial mats and modern stromatolites, microbially formed rocks found throughout the geological record. Some recent studies have shown the relevance of the lakes in this region for (i) the discovery of new extremophiles, particularly those tolerant to high UV and, furthermore, (ii) the study of biosignatures in stromatolites. In this work, a detailed survey, layer by layer, of the microbial diversity of the most widespread microbial mat in the Laguna Negra was reported, to unravel the spatial arrangement of the microbial community. The results reveal the vertical distribution of the main prokaryotic microbial taxa, and underline abundant Deinococcus-Thermus at the top of the microbial mat with high amounts of deinoxanthin, which may help the total community to cope with high UV radiation. This study allows a better understanding of the community strategies to thrive under environmental stressors in the Laguna Negra and its counterparts in the Altiplano-Puna region. The Altiplano-Puna region is a high-altitude plateau in South America characterized by extreme conditions, including the highest UV incidence on Earth. The Laguna Negra is a hypersaline lake located in the Catamarca Province, northwestern Argentina, where stromatolites and other microbialites are found, and where life is mostly restricted to microbial mats. In this study, a particular microbial mat that covers the shore of the lake was explored, to unravel its layer-by-layer vertical structure in response to the environmental stressors therein. Microbial community composition was assessed by high-throughput 16S rRNA gene sequencing and pigment content analyses, complemented with microscopy tools to characterize its spatial arrangement within the mat. The top layer of the mat has a remarkable UV-tolerance feature, characterized by the presence of Deinococcus-Thermus and deinoxanthin, which might reflect a shielding strategy to cope with high UV radiation. Chloroflexi and Deltaproteobacteria were abundant in the second and third underlying layers, respectively. The bottom layer harbors copious Halanaerobiaeota. Subspherical aggregates composed of calcite, extracellular polymeric substances, abundant diatoms, and other microorganisms were observed all along the mat as the main structural component. This detailed study provides insights into the strategies of microbial communities to thrive under high UV radiation and hypersalinity in high-altitude lakes in the Altiplano-Puna region. [ABSTRACT FROM AUTHOR]

The results of an analysis of pigments used in slips and designs deployed in ceramic assemblages recovered from archaeological sites located in different environments, expressing the socio‐historical process developed in the regions of Fiambalá and Chaschuil (Catamarca, Argentina) during the last 1500 years are presented. The sample, formed by fragments of different ceramic styles and natural pigments, was analysed via Raman spectroscopy and X‐ray diffraction. Results indicate the continuity in use of certain pigments (mainly hematite for red hues and Mn oxides in combination with magnetite for black paints) within the different socio‐political organizations that inhabited the region from the first to the 14th centuries ce, in spite of the diverse shades of colour, which suggests an intentional search linked with their cultural conventions. For the Inca Period, this scenery of continuities in minerals employed for reds and blacks is complemented by the use of new compounds (Ti oxide, apatite and gypsum) in order to generate the 'cream' tones applied as slips, all of which have not been identified for previous moments. [ABSTRACT FROM AUTHOR]

Laser–induced breakdown spectroscopy (LIBS) was applied for the rapid characterization of the elemental composition of archaeological remnants recovered from a military settlement dating from 1831, located at the center of the Argentinian Pampas (Buenos Aires province, Argentina). This research is part of an interdisciplinary project for the study of military fortifications within the field of historical archaeology. We present original results of the analysis of metallic artifacts, bones, potsherds, and colored glazed crockery of the site. The measurements included drilling through superficial weathering and corrosion layers to determine the underlying bulk composition of the materials, the analysis of glazing processes and the identification of pigments in the paintings. A new analytical approach was applied for the discrimination of elements corresponding to the pigments, the binder medium or the glaze from those belonging to the paste matrix which improved the LIBS performance. The obtained results provided useful information related to the characteristics, raw materials, manufacturing processes, use and provenance of the objects that contributed to achieve a more comprehensive knowledge of the archaeological context investigated. [Display omitted] • LIBS method was applied for the analysis of different archaeological remains. • Qualitative/semi-quantitative results of the elemental compositions were obtained. • Raw materials, manufacturing processes, use and provenance were studied. • The feasibility of LIBS for rapid analysis of archaeological objects was assessed. [ABSTRACT FROM AUTHOR]