Genesis and geomorphologic and ecological evolution of the Ganzirri salt marsh (Messina, Italy)

The results of geological and geomorphologic surveys on the salt marsh of Ganzirri (Pantano Grande), combined with geophysical researches and historiographical data, are reported here to define the genesis of the marsh and to evaluate the physical factors that influenced its recent evolution. The genesis of the Pantano Grande may be due to a state of equilibrium reached between differential lowering of the coastal plain, confined by normal faults, and generalized chain uplift. In particular, two normal faults are considered: the first borders the northern shore of the Pantano Grande, and the second bounds the Ionian coastal plain towards the south. Concerning the recent evolution of the Pantano Grande the importance of the sterile conglomerate outcrop, which borders the Ganzirri coastal plain, is stressed. The conglomerate is interposed between sediments that define the Pantano Grande basin, and the Ionian Sea, and influenced the water exchange between the marsh and the sea. Before the excavation of two canals that link up the Pantano Grande with the sea, the conglomerate, limiting the spread of benthic species, has definitively affected the ecological structure of the original marsh.