Flank Margin Caves In Telogenetic Limestones In Italy

Abstract

Almost 20% of Italy is characterized by the outcropping of carbonate massifs ranging in age from Cambrian to Quaternary. Coastal karst is present in many Italian regions: from North-East to South and West: the Gulf of Trieste, the Conero (South of Ancona, Marche), the Adriatic coast of Apulia including Gargano, Murge and Salento, Maratea in Basilicata, Cilento in Campania, Circeo and Gaeta in Latium, Argentario and Giannutri Island in Tuscany, the southernmost part of the Ligurian Alps, Palermo Mts., San Vito Lo Capo, Syracuse coast and Marettimo Island in Sicily, and, especially, in Sardinia, which has carbonate rocks touching the sea along the coast of Balai near Porto Torres, Capo Caccia-Punta Giglio (Alghero), Sinis and Buggerru along the western litoral, Capo Teulada and Capo Sant’Elia at Cagliari, Capo Figari, Tavolara Island and the Gulf of Orosei along the eastern mountainside. Recent researches have revealed several coastal cave systems that have a clear origin by mixing corrosion, in which the aggressive solution derives from the mixing between saline and fresh water at the watertable interface (the so-called flank margin caves). Glacioeustasy and tectonic movements can control the position of sea level with respect to coastal carbonate outcrops. For this reason these coastal caves represent useful records of sea-level stillstands. These caves are normally organized in sub-horizontal levels, and are characterized by the lack of high flow velocity markers (scallops) and alluvial sediments. Instead, they show rounded cave passage morphologies, often with horizontal wall notches, a characteristic swiss-cheese or sponge morphology, and passages that narrow going away from the coastline (due to the decreasing of sea water influence and mixing-corrosion effect). This paper describes some flank margin cave systems found in Apulia, Sicily, and Sardinia. In particular, five cave systems are illustrated: Sant’Angelo caves (Apulia), Pellegrino and Rumena caves (Sicily), and Giuanniccu Mene cave and Fico cave (Sardinia), explaining their relationship with past sea levels and local uplift rate.