Trace element variations in an archeological carbonate deposit from the antique city of Ostia: Environmental and archeological implications

High resolution laser ablation ICP-MS analyses are performed along the growth axis of an archaeological carbonate deposit from a water tower in the antique city of Ostia (Italy). Results show a composite structure with high frequency cycles, thought to be seasonal, and longer-term variations in Mg/Ca, Sr/Ca, Ba/Ca, Pb/Ca and U/Ca ratios. Changes in the broad trace element composition at the beginning of the deposit are interpreted as the hallmark of important modifications in the sources supplying the water to the city. Our study suggests that trace elements analysis in archaeological carbonates have the potential to provide high-resolution seasonal records, which could give insights into historic environment variability and past policy of natural resource administration.