RESUMO: A presente contribuição descreve a implementação da rotina de microanálises isotópicas de Sr via LA-MC-ICP-MS no CPGeo-USP. A escolha por uma rotina analítica envolvendo a medição de meias-massas (p.ex. 171Yb2+) possibilitou a adequada correção das interferências de lantanídeos, permitindo a determinação precisa de isotopos de Sr em fases minerais acessórias ricas em REE, como a apatita. O método de medições on-peak-zero permitiu a correção efetiva das contribuições de níveis de branco (Kr + Sr residual na linha de gás) aos sinais de amostras desconhecidas. As razões 87Sr/86Sr obtidas em diferentes materiais de referência (e.g. coral moderno e o clinopiroxênio Batjberg) alcançaram precisão menor que 57 ppm ( ±0.000057 2σ SD) em comparação com os valores certificados via TIMS. A qualidade da rotina implementada é também atestada pela proximidade dos valores aceitos e obtidos para razões isotópicas estáveis. O grau de exatidão atigindo permite a identificação e o estudo de heterogeneidades isotópicas em escala micrométricas em variados minerais ricos em Sr (apatita, carbonatos, plagioclásio e clinopiroxênio) com importantes implicações para a comprensão de processos geoquímicos relevantes, particulamente processos de assimilação-fraccionamento-contaminação, heterogeneidades químicas e mistura de magmas.

ABSTRACT: This contribution describes the successful implementation of in situ Sr isotope analyses by LA-MC-ICP-MS at the CPGeo-USP. The choice for an analytical configuration using measurements of half-masses allows the accurate assessment of lanthanide interferences, permitting the determination of Sr isotopes in important REE-rich accessory phases, such as apatite. Likewise, the on-peak-zero method effectively corrects the background contribution (both from Kr and residual Sr contributions from previous ablations) to the signals of the unknown samples. The analytical campaigns resulted in an accuracy, in respect to reference TIMS values, better than 57 ppm (~ ±0.000057 2σ SD) for a modern coral and the Batjberg clinopyroxene which impart significant quality to our data. Similarly, the majority of the stable Sr isotope ratios are close to the accepted values, which also confirms the effectiveness of the method. The achieved accuracy allows the identification and investigation of spatially-controlled isotopic heterogeneities on the micrometric scale in several Sr-rich minerals (apatite, carbonates, plagioclase, and clinopyroxene) with important implications to the understanding of relevant geochemical processes, particularly AFC, source geochemical heterogeneities and magma-mixing.

Between the years 1999 and 2001, the individual Nº1 was discovered in the archaeological site "Alero Ernesto Marifilo-1", to the north of Lake Calafquén, region Los Ríos, Chile. The infant was dated in the period 6,030 ± 40 BP. By means of Dental Anthropology, this work attempts to interpret the type of life that individual Nº1 had, with respect to the state of health and type of diet, as well as the age at the time of death. In addition, it tries to compare the archaeological remainders of wildlife and vegetation found at the excavation site, with the results obtained from the analysis of the dental structures of the infant. The age of individual Nº1 was determined using the method of dental eruption. In order to determine its state of health, the following dental parameters were used: caries, dental hypoplasia, abscesses, chipping, alveolar retraction, and dental wear. Its diet on the other hand, only required the followed parameters: carie, chipping, and dental wear. The oral and general health was good, where each parameter was manifested to a very small extent, and the diet of the infant can be considered mixed, consisting of components such as freshwater, meats and fruits, obtained from the ecosystem where individual Nº 1 lived. Finally, the results obtained by using Dental Anthropology conform to the results obtained from studies of the archaeological site.

Entre 1999 y 2001, se realizó el hallazgo del Individuo Nº 1 en el sitio "Alero Ernesto Marifilo-1", al norte del lago Calafquén, Región de Los Ríos, Chile. Este fue fechado en 6.030 ± 40 AP. En el presente trabajo, a través de la antropología dental, se pretende interpretar el tipo de vida que tuvo el Individuo Nº 1, en relación a su estado de salud y dieta, así como su edad en el momento del deceso. Además, se intenta comparar los restos arqueológicos faunísticos y vegetacionales hallados en el sitio con los resultados obtenidos en el análisis de las piezas dentales. Se determinó su edad mediante el método de erupción dental. Para determinar el estado de salud se utilizaron los parámetros: caries, chipping, desgaste dental, hipoplasia dental, abscesos y retracción alveolar. Para conocer la dieta se utilizó los tres primeros parámetros nombrados anteriormente. Se constató que la salud oral y general del infante fue buena, dado que cada parámetro se manifestó en grados leves. Su dieta se consideró como mixta, con componentes dulceacuícolas, obtenidos del ecosistema donde habitó. Finalmente, estos resultados son concordantes con los obtenidos en los estudios del sitio.

This work presents the VALIDATION SPREADSHEET, a public domain tool that can be used to evaluate the figures of merit for univariate analytical methods. A real example of BTEX determination in environmental samples is included to illustrate its use. The spreadsheet has been developed for Excel® and Open Office®, and is available on the internet at http//lqta.iqm.unicamp.br.