Provenance des roches à base d’hématite exploitées à Diepkloof Rock Shelter, Afrique du Sud : synthèse et implications socio-économiques
p. 69-89
Résumé
Hematite is one of the most common red pigments used by hunter-gatherer societies. In Africa, the earliest and unambiguous evidence for the use of red ferruginous pigments dates to the early Middle Stone Age (MSA), more than 200 ky ago. Usually referred to as “ochre”, they were intensively exploited in Southern Africa from about 160 ky. Hundreds of ochre fragments have been found in MSA layers from dozens of South African sites. The powder extracted from these red rocks is assumed to have been involved in a variety of activities, for body painting, for medicinal or ritual purposes, in hide treatment or as a loading agent in adhesives. Direct evidence of its use by MSA populations is scarce and mostly inferred from powder residues staining archaeological artifacts, such as backed tools or shell beads. Although red pigment use by early modern humans has often been interpreted as reflecting symbolically mediated and complex behaviors, the way they were collected and selected before being used remains poorly documented. Provenance studies are among the most powerful approaches to reconstruct procurement strategies and to discuss selection criteria. In this paper we investigate the provenance of ochre pieces from the MSA units of Diepkloof Rock Shelter, South Africa, in order to discuss the complexity of ochre procurement. Samples were examined with a binocular microscope and a part of them was submitted to chemical analyses by SEM-EDS (micro-structure), XRD (mineralogical composition), ICP-OES and ICP-MS (composition in major and trace elements). They were compared with a geological database constituted of samples from 12 sources located around the site.
Ochre pieces from Diepkloof were shown to belong to three main categories of rocks: clayish sedimentary rocks (shale) ; intensively ferruginized nodules (nodular ferricretes) ; partially ferruginized sedimentary rocks (shale/ferricrete). Petrological observations and mineralogical analyses suggest a local provenance for a majority of the shale pieces, probably from a shale bed located directly in the back of the shelter. A significant number is exogenous however, and several were shown to be non-local. Geochemical data interrogated by statistical methods confirm the presence of both local and exogenous shale pieces. In comparison to shale pieces, no ferricrete sources are encountered in the vicinity of the site. Ferricrete pieces are exogenous and some of them are probably non local according to their micro-structure. However the ferricrete sources do not show clear mineralogical or geochemical fingerprints as the shale sources do. Regarding the provenance of shale/ferricrete pieces, similar conclusions were reached. According to these results, raw materials containing high iron oxide amounts were preferentially collected although they required long distance movements. Most of the non-local ochre pieces (shale and ferricrete), come from formations located to the south-west, upstream of the valley where the site is located. They are all located in Howiesons Poort units. At least one shale piece could come from a more distant area located to the north-east, where deeper valleys are encountered (Cederberg area). Such connections between different valleys suggest long distance group mobility or group exchange. In conclusion, ochre procurement at Diepkloof followed complex patterns during the Howiesons Poort, involving local supply, day trips, and possibly long distance mobility or group exchange.
Index
Mots-clés
hématite, ocre, provenance, minéralogie, géochimie, Middle Stone Age, Afrique du Sud, stratégies d’approvisionnementKeywords
hematite, ochre, provenance, mineralogy, geochemistry, Middle Stone Age, South Africa, procurement strategieIndex géographique
BelgiqueTexte
Citer cet article
Référence papier
Laure Dayet, « Provenance des roches à base d’hématite exploitées à Diepkloof Rock Shelter, Afrique du Sud : synthèse et implications socio-économiques », ERAUL, 143 | 2016, 69-89.
Référence électronique
Laure Dayet, « Provenance des roches à base d’hématite exploitées à Diepkloof Rock Shelter, Afrique du Sud : synthèse et implications socio-économiques », ERAUL [En ligne], 143 | 2016, mis en ligne le 29 November 2024, consulté le 10 January 2025. URL : http://popups.lib.uliege.be/3041-5527/index.php?id=828
Auteur
Laure Dayet
CNRS, UMR5060-IRAMAT, Université Bordeaux Montaigne, 33607 Pessac (France)