A multi-analytical evaluation of the depositional pattern on open-air rock art panels at “Abrigo del Lince” (Badajoz, Spain)

Abstract

Microscopic observation correlated with chemical–mineralogical characterization was performed on pigment samples from “Abrigo del Lince” rock art site (V-IV millennium BC), in order to provide contributions to the study of prehistoric schematic art on granite in the province of Badajoz (Spain). The research objectives include the understanding of technological and cultural aspects, as well as of conservation and deterioration issues related to the pictographs. The multi-analytical approach encompasses the integration of microscopic observation, SEM–EDS analysis, micro-Raman spectroscopy, and ATR-FTIR and allowed to achieve a multispectral overview of the samples and to describe their varied composition and the alteration pattern which connects them. The main phases overlying the granitic bedrock and involved in this sequence are as follows: hematite, whewellite, and gypsum. While hematite could be stratigraphically considered the most ancient layer and assigned to the use of red ochre as a pigment, whewellite and gypsum are the main constituent of the alteration layer which forms a patina over the pictographs, due to weathering processes. Finally, the role of biofilms in rock art conservation is discussed, suggesting that, especially for what concern thin and homogenous layers of oxalates, their presence should not be necessarily considered an issue.

Archeometrical Characterization of Rock Art Pigments from Puerto Roque Open-Air Rock Art Shelter (Valencia De Alcantara, Extremadura, Spain)

“…The ATR-FTIR results corroborate the findings obtained from other methods. The databases already used in other studies [15,17,59,60] were used to assign and interpret the spectra obtained through the ATR-FTIR analysis of the samples analysed. ATR-FTIR spectra are composed of peaks that, based on the detectability of the sample, indicate clay minerals and their structure, composition and structural changes resulting from chemical modifications.…”

“…The scarcity of detected organic binders underscores the challenges and complexities associated with their preservation over time, shedding light on the resilient and enduring nature of the inorganic elements present in rock art pigments [63]. This nuanced understanding invites further exploration into the dynamic interplay between organic and inorganic components, offering valuable insights into the long-term preservation and alterations that shape the captivating world of rock art [17,64]. In any case, our inability to find organic compounds could be due to the degradation of binders, which could result in oxalates being detected in some samples [65].…”

“…While numerous studies aimed at comprehending this distinctive style of rock art studies have been conducted since the early 20th century, commencing with the work of Henri Breuil, it is noteworthy that only in recent times have archaeometric investigations been applied to rock art sites in this region [13][14][15][16][17].…”

Archeometrical Characterization of Rock-Art Pigments from Puerto Roque Open-Air Rock Art Shelter (Valencia De Alcantara, Extremadura, Spain)

“…The ATR-FTIR results corroborate the findings obtained from other methods. The databases already used in other studies [15,17,59,60] were used to assign and interpret the spectra obtained through the ATR-FTIR analysis of the samples analysed. FTIR spectra are composed of peaks that, based on the detectability of the sample, clay minerals and their structure, composition and structural changes resulting from chemical modifications.…”

“…This array includes several typologies of figures, notably "ramiforms" (a preferred Iberian term for what is also described as a tree-like linear motif), circular-shaped figures, lines, and anthropomorphic representations (see Figure 3). While numerous studies aimed at comprehending this distinctive style of rock art have been conducted since the early 20th century, commencing with the work of Henri Breuil, it is noteworthy that only in recent times have archaeometric investigations been applied to rock art sites in this region [13][14][15][16][17].…”