CONICET | Buscador de Institutos y Recursos Humanos

This work aims discussing the contribution of environmental and technological factorsin rock art painting preservation, through a three-years experimental program and twoarchaeological cases from Patagonia (South America). Concerning technologicalfactors, microscopic information of experimental and archaeological contexts indicatethat loamy pigments have a better preservation potential, likely related to the highbinder-adsorption capacity of small particles, resulting in a strong pigment agglutinationand substrate adherence. Mechanical entrapment/translocation of small particles into thesubstrate further contributes to preservation. Experimental paints also evidence thatblood-bearing paints present preservation advantages over fat/water-based ones,probably due to clotting and drying processes which agglutinate pigments and seal rockvoids, avoiding binder migration. In contrast, experimental gypsum- and charcoal-basedpaints show a rapid and significant deterioration. The low archaeological expectancyderived from these results is supported by the scarce and/or ambiguous regionalrepresentation of these pigments in ancient Patagonian paintings. Among naturalprocesses, water-related processes (i.e., rainfall, snow, freezing and water infiltration)play a decisive role in the physicochemical paint degradation, also favoring bioactivity.Raman spectroscopy of neoformed white crystals in experimental paints may evidence,in a short-term, a first stage of the profuse biomineralizations observed archaeologically,associated with lichens, fungus and endolithic organisms. Finally, sheep rubbing andwind abrasion are proposed as the main agents affecting vertical frequencies andintegrity of archaeological motifs at the cave and open-air contexts, respectively,whereas insolation likely impact in lateral frequencies, motif color and weatheringstages at the open-air site too.

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