Decay phenomena of marbles in the archaeological site of Hierapolis of Phrygiae (Denizli, Turkey)

The paper describes the state of conservation and the decay phenomena of marble elements of the ancient Phrygian city of Hierapolis in the Denizli district in Turkey. The archaeological site presents some peculiarities that make it unique in terms of conservation and decay phenomena of marbles and travertines. Environmental factors (i.e. thermal springs, high thermal stress, seismic faults) together with the microstructural characteristics of the typologies of marble play a fundamental role on the durability and the state of conservation of the materials. A lot of architectonic elements, belonging to several monuments (e.g. Civil Agorà, Sanctuary of Apollo, Ploutonion, Marble Stoà, Gymnasium, North Agorà, Stoà near the Springs, Bouleuterion) were selected and investigated. A monitoring network in the areas of the Ploutonion (positioned close to the major fault) and the Sanctuary of Apollo was installed in August 2013. The network consists of several sensors measuring environmental parameters (T and RH%), both in external and in confined environments and gases (CO2, CO, O2, H2S). Stone sampling was carried out for laboratory analyses (XRD, FT-IR, OM, SEM-EDS). In parallel, the geochemical characterisation of waters circulating in the site and dissolved gases was carried out. Furthermore, the biological characterisation of patinas affecting some architectonic elements, was performed.