Choosing the site, getting the stones, building the dolmens: local sourcing of andesites at the El Pozuelo megalithic complex (Huelva, Spain)

Abstract

The geoarchaeological study focuses on the lithological characterization and provenance determination of the rocks of the El Pozuelo dolmens. The difficulty of identifying volcanic rocks in the intensely altered and deformed environment of the Iberian Pyrite Belt has required the implementation of a research methodology combining the archaeological and geological analysis of the megaliths and the area surrounding the Los Llanetes group. A total of 29 thin sections and 14 geochemical analyses (ICP-AES, ICP-MS and REE) have been carried out on samples from the dolmens and potential source areas, focusing on the chemical elements considered immobile during alteration processes. The petrological analyses confirm the identification of different andesite lithotypes and enable us to correlate the rocks used in the construction of the megaliths with source areas and quarries located within a 50–350 m radius. Several patterns are observed in the selection of the rocks, based on the material, visual and symbolic properties of the different lithologies. Foliated andesite is the most common stone used in the monuments, due to its excellent physical properties and technological suitability for extraction and transformation into megalithic supports. Other types of andesite (sheared, massive and amphibole-phyric), white quartz, ferruginous agglomerate and gabbro were also used for different architectural purposes. The results confirm the importance of locally available suitable rocks in determining site location, raw material procurement and monument construction during the Late Neolithic.