Rock art taphonomy: inorganic and organic changes of experimental paintings in Patagonia

OZÁN, IVANA LAURA; ORIOLO, SEBASTIÁN; CASTRO, MARÍA ANA; LATORRE, ANDRÉS

Workshop; Actualistic Taphonomy; 2021

Only a few actualistic studies concerning rock art taphonomy combined with robust analytical data have been carried out so far worldwide. In this sense, the present work aims to analyze compositional and mechanical changes of a set of experimental paintings specimens at three different localities in central and southern Argentina, in order to obtain information to discuss the potential archaeological bias related to the abundance, diversity and distribution of rock art paintings in the Patagonian region. Based on ethnographical and archaeological data, and using Patagonian raw materials, fifteen combinations of pigments (hematite with different pre-treatments, gypsum and charcoal), binders (Lama guanicoe fat, urine, blood and saliva) and additives (blood and gypsum) were manufactured, resulting in red, white and black paintings. They were all applied by fingers on basalt fragments, a ubiquitous rock art support in the Patagonian region. Raman spectroscopy was carried out on each raw material, painting combination and support to get the ?time 0? spectra. Qualitative macroscopic characterization of the painting was also done to evaluate color, adherence capacity, painting thickness and roughness among others. After analysis, resulting paintings were installed at three different localities: Buenos Aires (34°S 58°W), Bariloche (41° S 71°W) and Rio Gallegos (51°S 69°W), in order to evaluate weathering rates and degrees of both organic and inorganic components of the paintings, associated with different physico-chemical and biological conditions (i.e., isolation, temperature, humidity, wind action, bioactivity). Raman spectra to contrast with the ?time 0? ones will be carried out on each painting combination after a certain period of time, along with a macroscopic characterization focused on changes in the painting color (i.e., hue, chroma, value) and quality (e.g., fissures, stains, loss of painting surface and among others).