Micro-Raman spectroscopy and complementary techniques applied for the analysis of rock art paintings at the archaeological locality La Angostura, lower valley of Chubut River (Patagonia, Argentina)

GURIN, MARÍA CELESTER; MAZZUCA MARCIA; GOMEZ OTERO, JULIETA; MAIER, MARTA

Archaeological and Anthropological Sciences

Springer-Verlag GmbH Germany, part of Springer Nature

Lugar: Berlin; Año: 2021

In this paper, we characterized for the first time the painting materials in rock artpanels of the Patagonian archaeological locality La Angostura using amethodological approach that combined micro-Raman spectroscopy, attenuatedtotal reflection Fourier Transform infrared spectroscopy, and X-ray fluorescencespectroscopy. In this way, we obtained detailed information on the red, green, andblack pigments as well as on accessory minerals present in the paints. Hematite wasthe chromophore in the red paintings while celadonite and glauconite wereidentified in the green motifs. A manganese oxide, presumably pyrolusite, wascharacterized as the black pigment. The pigment compositions were also comparedto those of natural sediments collected along the valley of the Chubut River, but thecomponents of the red and green sediment samples differed from those present inthe rock art paints. In the red motifs of two of the rock art panels, a relevantfinding was the presence of gypsum and anhydrite as a priming layer of thecorrugated rock support onto which the reds paints were applied. This revealed adifferent painting technique in comparison to that at the other analyzed panels ofLa Angostura where paints were applied as thin layers on a smooth surface of therock support. As far as we know, this is the first report on the identification ofgypsum and anhydrite as components of a preparation layer in Patagonian rock art.This result contributes to the open discussion on the origin and function of calciumsulfate in rock art.