Non-invasive portable instrumentation to study Palaeolithic rock paintings: the case of La Pena Cave in San Roman de Candamo (Asturias, Spain)

La Pena de Candamo Cave, listed as World Heritage by UNESCO in 2008, preserves one of the most important collections of parietal art in the North of Spain and there is an urgent need to evaluate the status of the cave both archaeologically and from the conservation and restoration points of view. In this work, the usefulness of non-invasive mobile instrumentation, such as Raman and EDXRF spectroscopies, is shown when this type of assessments are required under adverse experimental conditions. In addition to the rapid diagnosis that this non-invasive and mobile instrumentation provided, based on the subsequent multivariate analysis of collected spectra, it was possible the identification of the main pigments of the rock art as well as their different origins. Finally, this study also showed the biodeterioration and decalcification processes observed in some areas of the cave and revealed the damage suffered during decades. The effects of such decaying processes over pictorial layers show up the need of a continuous preventive control of paintings in order to minimise further deteriorations. (C) 2012 Elsevier Ltd. All rights reserved.