Sulfuric acid caves of Italy: an overview.

The general geodynamic situation of Italy is quite complex. The land has undergone several stages of formation, compressed between the African and the Eurasian continents. The phase of extensional tectonics governed by the rollback of continental terrains (Corsica, Sardinia, Balearic Islands, Kabylies blocks, and Calabria) caused the generation of the Apennine chain, which crosses northwest to southeast and is the backbone of Italy’s mainland. The structure of the Apennine chain contains many thrusts, horst and graben structures, and deep faults, as well as the widespread presence of mainly Mesozoic carbonate outcrops. This has caused the formation of deep karstic circulation systems, as evidenced by the abundance of hydrothermal springs and associated travertine deposits. Furthermore, the presence, at depth, of both hydrocarbon reservoirs and Triassic gypsum deposits is responsible for the presence of rising waters rich in H2S.