Micro-Raman spectroscopy for the analysis of materials found in rock art shelters in Piedra Parada valley, Chubut province, Argentinian Patagonia

Abstract

Micro-Raman spectroscopy was employed for the analysis of samples collected from the shelters Campo Cerda 1, Angostura Blanca and Campo Moncada 1 located in Piedra Parada valley, Chubut province, Argentinian Patagonia. Different coloured layers, degradation products and rock supports were analysed. Haematite (α-Fe2O3), goethite (α-FeOOH), green earth and gypsum (CaSO4 ·2H2O) were responsible for the main colouration of the pigmented layers together with other components. Gypsum, Ca-oxalates and calcite were the major degradation materials affecting the rock paintings and the rock support. Different types of silicates, apatite [Ca5(PO4)3(F,Cl,OH)] and goethite were positively characterized in the rock support. Point analysis and micro-Raman mappings contributed towards a better understanding of the materials and layer sequencing of the samples extracted.