Petrographic and geochemical characterization of Eocene limestones from Thugga / Dougga (Tunisia): Implications for the provenance of stones used in construction and sculpture in the ancient town

Résumé fourni par la source

• Petrographic and geochemical analysis of Eocene limestones at Dougga. • Ten lithofacies tied to lithostratigraphic units, mapped across the site. • Monumental stone was locally sourced within 1 km of Dougga. • Stone choice reflects durability, carving ease, and function of use. • Quarrying practices evolved from Punic to Roman Imperial periods. The ancient town of Dougga (Tunisia), inscribed on the UNESCO World Heritage List, provides a unique opportunity to investigate the provenance and selection of construction materials used from the Punic-Numidian to the Roman Imperial periods. This study presents an integrated petrographic, sedimentological, and geochemical characterization of Eocene limestones surrounding Dougga, combined with the analysis of 19 stone samples collected from architectural elements spanning the 3rd century BCE to the 3rd century CE. Field mapping and detailed stratigraphic logging identified five main lithostratigraphic units (U1–U5), composed of ten distinct lithofacies. Diagnostic facies such as Nummulites - Discocyclina floatstones (LF3), flat Nummulites floatstones (LF2.1, LF2.2), and planktonic foraminiferal packstones (LF6) allowed robust correlations between archaeological artifacts and specific quarry zones located within 1 km of the site. The findings suggest that the choice of materials was largely dictated by mechanical durability, ease of carving, and visual qualities. Soft, chalky limestones (LF6) were employed for smaller or low-rise structures, whereas robust nummulitic facies (LF1.1, LF2.2, LF3) were preferred for monumental architecture, and fine-grained lithotypes (LF5) were selected for detailed sculptural work. During the Roman period, the exploitation of floatstones with flat Nummulites (LF2.1, LF2.2) and Nummulites - Discocyclina facies (LF3) became more systematic, particularly for columns and large ashlar blocks, while homogeneous fine-grained stones (LF5) remained the material of choice for statues. This combined petrographic and geochemical approach provides a strong basis for provenance studies of ancient building stones, highlighting both the strategic use of local resources and evolving quarrying practices over time.

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