Análise de cerâmicas arqueológicas do Sambaqui do Bacanga (São Luís, MA) por EDXRF portátil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

“Sambaqui do Bacanga” archaeological site is located in the Island of São Luis -Maranhão – Brazil, in the region bathed by the Bacanga River. A tratigraphic collection of 78 ceramic fragments was collected during the years 2005 and 2006, to perform a qualitative analysis of the chemical elements employing a Portable System of Energy Dispersive X-ray Fluorescence (PXRF). The aims of the work were: verify the existence of painting vestiges in the fragments; verify if there is some kind of treatment in the concave and convex sides in relation to the ceramic paste of the fragments and use the grouping analysis to verify the similarity among the chemical elements identified in the fragments of the same stratigraphic level and different levels. The portable system (PXRF-LFNA-02) [1] consists of a X-ray tube (Ag target, 50 µm Ag filter, 4 W) to excite the samples, a Si-PIN detector (221 eV FWHM at 5.9 keV and 25 µm Be window), a specially designed holder for the excitation-detection system and samples positioning, with the standard electronics and a notebook for the data acquisition. The Quantitative X-Ray Analysis software (WinQXAS), distributed by the International Atomic Energy Agency (IAEA), was used for the spectra analysis. The elements K, Ca, Ti, Mn, Fe, Zn, Br, Rb, Sr, Y, Zr e Pb were identified in the different fragments and only Fe, Ca, Sr, Zr, Mn, Ti e Zn were common elements for all of them, indicating that these elements are present in the raw material used in the manufacture of the fragments. Only one fragment presented the remaining of painting. It was observed a larger concentration of Fe in this region in relation to areas without painting in the same side. This indicates that a material with iron oxide was used to make the painting. The elements Fe, Sr, Mn, Ti and Zn are present, systematically, with larger intensities on concave and convex sides in relation to the ceramic paste for 43 among the 68 analyzed fragments, indicating a different surface treatment that leads to an enrichment of those elements. Cluster analysis of the Ward Method type was performed with the ceramic fragments from the 10-20 cm, 132 cm and 144 cm levels. The fragments were grouped in three different clusters, except for two fragments from the 132 cm level, which grouped in the same group of the fragments from 10-20 cm level. This result indicates three different sources of clay for the studied pottery fragments.

ASSUNTO(S)

física nuclear cerâmica arqueológica - técnicas e aplicações nucleares fluorescência de raio x arqueometria arqueologia e física nuclear physics x-ray fluorescence archaeological ceramics archaeometry

ACESSO AO ARTIGO

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