Geochemical study of carbonate concretions from the aqueduct of Nîmes (southern France): a climatic record for the first centuries AD?

Yacine Benjelloun (1) , Julie Carlut (1) , Jean-François Hélie (2) , Gilles Chazot (3) , Laurence Le Callonnec (4)

1 IPGP - Institut de Physique du Globe de Paris
2 GEOTOP - Centre de recherche sur la dynamique du système Terre
3 IUEM - Institut Universitaire Européen de la Mer
4 iSTeP - Institut des Sciences de la Terre de Paris

The first centuries AD in the Mediterranean region have generally been associated with a warm, stable climate. High-resolution sedimentary archives sensitive to local environmental change are needed to switch from this general frame to the regional scale. Similarly to cave speleothems, laminated carbonate deposits can grow in the channels of aqueducts which transported water from karstic springs during the Roman period. The deposits of the aqueduct of Nîmes (SE France) are exceptional since they may represent several centuries of paleoenvironmental record with a seasonal resolution. δ18O, δ13C and trace elements were measured in three samples from this aqueduct. The comparison of the geochemical signals with the fine texture of the deposits evidenced the seasonal nature of the lamination observed. This allowed us to document the evolution of environment as recorded through the deposit for the period 50–275 AD. The concretions of the aqueduct of Nîmes document rather stable climatic conditions for the first three centuries AD, as well as a local vegetation change possibly linked to an increased in land use.

Keywords: Geochemistry; Palaeoclimate; Sedimentology

Domains: Geochemistry; Climatology

Yacine Benjelloun, Julie Carlut, Jean-François Hélie, Gilles Chazot, Laurence Le Callonnec. Geochemical study of carbonate concretions from the aqueduct of Nîmes (southern France): a climatic record for the first centuries AD?. Scientific Reports, 2019, 9 (1), pp.5209. ⟨10.1038/s41598-019-41620-4⟩. ⟨hal-02094472⟩