Potencialidade das assinaturas isotópicas de Pb por espectrometria de massa ICP-MS e TIMS no estudo da proveniência dos azulejos das fachadas históricas de Belém, PA

Since the eighteenth century, frontages of old buildings from the city of Belem and others Brazilian cities like Salvador, Recife, Rio de Janeiro and São Luis, have been covered with tiles imported principally from Portugal and from others countries of Western Europe, constituting and valorous historical patrimony. The purpose of this study is to evaluate the potentiality of Pb isotopes as a tool for the identification of the provenience of the tiles of historical building from Belem by lead isotope analyses of the tile’s glaze compared with possible Pb ores deposits sources in Western Europe. The study included a comparison of Pb isotopic results obtained by Thermo-ionization mass spectrometry (TIMS) and ICP- mass spectrometry (ICP-MS) on a Finnigan MAT 262 mass spectrometer and a Thermo-Finnigan Neptune ICP-MS mass spectrometer, respectively. Pb isotopes were determined on 36 samples of tiles (23 tiles from Portugal, 5 tiles from England, 4 tiles from France, 4 from Germany). Six samples of tile from the city of São Luis an of unknowm origin , including from de seventeen century, 4 from the eighteenth century and from nineteenth century were also investigated. Additionaly, Pb isotope analyses were also performed on 8 samples of Brazilian modern tiles to evaluate possible distinction between isotopic signature of original European tiles and national replications. A compilation of isotopic signatures of the main Pb deposits in Western Europe and Brazil was necessary in order to compare the Pb isotope compositions of the deposits and tiles. According to the chemical composition and, principally, the high Pb contents of the glaze a simple analytical procedure by HF leaching was adopted for Pb extraction of the glaze, without chemical separation and purification by ion-exchange chromatography. The measurements of Pb isotopic composition by TIMS and ICP-MS on the same samples displayed some differences but these differences do not affect the interpretations of the results. The 208Pb/206Pb vs. 207Pb/206Pb diagram is ...