Il sistema idrotermale sottomarino a largo dell'Isola di Zannone (Arcipelago Pontino occidentale, Mar Tirreno)

Recent studies, coordinated by the CNR-IGAG, have allowed us to discover a previously unknown active hydrothermal system off the coast of Zannone Island (western Pontine Archipelago, central Tyrrhenian Sea). Morphological features produced by hydrothermal activity include five, large-scale depressions (length >250 m) detected using multibeam data acquired by research vessels of the National Research Council (CNR, Italy). After this discovery, multidisciplinary investigations (geophysical, geochemical, micro-paleontological, mineralogica-petrographical, etc) were conducted within the framework of the Ritmare Project to define the processes that formed the depressions, to infer the origin of the fluids, and to explore the sub-seafloor architecture. The main focus was devoted to the most complex depression among the five: the Zannone Giant Pockmark - ZGP, which is characterized by several active fluid emissions. The ZGP represents a unique case in the Mediterranean of large-scale complex depression (0.5 km2) formed by numerous craters, mounds, and pockmarks associated with different types of emissions. To date, examples of similar hydrothermal morphologies are very rare (i.e., depression located offshore Panarea Island, MONECKE et alii, 2012; the Yellowstone Lake seafloor, MORGAN et alii, 2003), and their formation and evolution are not yet well understood (e.g., explosive hydrothermal activity, collapse, self-sealing, and alteration processes).