Multidisciplinary characterization of the buried travertine body of Prima Porta (Central Italy)

Abstract

A buried travertine deposit, identified in a well at Prima Porta (to the north west of Rome, Italy), was investigated using a multidisciplinary approach that included stable isotope geochemistry, mineralogy, petrography and radiometric dating. The travertine body is located just along the western boundary of the Tiber valley, a morpho-tectonic depression of extensional origin; it is associated with the rise of a deep-seated, hypothermal, saline, CO2-rich fluid. The depositional environment was inferred by the macroscopic features of core and microfacies analysis, which suggested that travertine deposition was associated with a low to moderate energy environment, such as gently-dipping, shallow pools on low-angle, terraced slopes. A hydrothermal system, characterised by long circulation paths at depth, and deeply derived CO2-dominated fluids, are supported by geochemical analyses. According to radiometric dating, travertine deposition occurred from between 53.5 ± 10 ka to 24.2 ± 4.7 ka; the activation of the travertine-depositing spring was probably coeval with the wettest climatic conditions occurring during MIS3, whereas the end of deposition coincides with the cold and arid phase of the last glacial maximum.