On-field Raman spectroscopy of Patagonian prehistoric rock art: Pigments, alteration products and substrata

VAZQUEZ, C; MARIANA CARBALLIDO CALATAYUD; LUC MOENS; EMMANUEL VARGAS ; CRISTINA BELLELLI; OSCAR PALACIOS; ANASTASIA ROUSAKI; VERONICA ALDAZABAL; ADAM HAJDUK; PETER VANDENABEELE; VAZQUEZ, C; MARIANA CARBALLIDO CALATAYUD; LUC MOENS; EMMANUEL VARGAS ; CRISTINA BELLELLI; OSCAR PALACIOS; ANASTASIA ROUSAKI; VERONICA ALDAZABAL; ADAM HAJDUK; PETER VANDENABEELE

TRAC-TRENDS IN ANALYTICAL CHEMISTRY

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2018 vol. 105 p. 338 - 351

0165-9936

An extensive in situ Raman spectroscopic campaign was performed on archaeological sites in threedifferent provinces in Patagonia, Argentina (Neuquen, Río Negro and Chubut). 16 open air shelters located in different environments (forests, ecotones, steppes) were investigated and interpreted in termsof pigments used and the identification of substrata. Special attention was given to the alterationproducts and accretions that were found on the rock art paintings of the shelters and on the surface ofthe rock walls, as they can affect and damage this magnificent works of art. Haematite (a-Fe2O3) was themain chromophore that was found on the red paintings of the most of the shelters studied. The greenearth glauconite, was identified only in one case, by using a red (785 nm) and a green laser (532 nm).Other minerals and silicates were found on the coloured areas but also on the rock support. Calcite(CaCO3) and gypsum (CaSO4 2H2O) crystallization was identified on the paintings, crusts and rocksurfaces, in combination or alone, and are associated with weathering. In some cases the shelters were soseverely degraded that no Raman signal of pigments and/or other components could be retrieved. Calciumoxalates were also detected in several figures and motifs in different shelters