THE SUBSIDENCE HISTORY OF THE NORTHERN HYBLEAN PLATEAU MARGIN, SOUTHEASTERN SICILY

The southeastern corner of Sicily is dominated by the Hyblean plateau which is composed of carbonate rocks of Triassic to Miocene age. The p lateau forms part of the African foreland which collided during Tertia ry times with the Calabrian Arc giving rise to the Maghrebian thrust b elt. The present study attempts to reconstruct the subsidence history of the northern Hyblean plateau. During the Neogene climax of the plat e collision this area has been a centre for widespread basaltic volcan ic activity (8-1 Ma) and uplift. At the close of the collisional event s (Pliocene-Early Pleistocene) the area under consideration has been a ffected by subsidence and the progressive consumption of the northern margin of the Hyblean plateau led to the development of the modem fore deep. A quantitative analysis was done by one-dimensional Airy backstr ipping of seven deep wells located on this crucial part of the Hyblean plateau. The results of the analysis show that the subsidence history of the northern Hyblean plateau area is characterized by four main ph ases, similar to other domains in the central and eastern Mediterranea n basins. These phases are: (a) Neotethyan rifting during Late Triassi c-Early Jurassic time; (b) a slow thermal subsidence from Early Jurass ic until Late Cretaceous time, leading to the formation of a widesprea d Mesozoic carbonate platform; (c) compressional phase during Late Cre taceous-Palaeogene time, which resulted in the formation of fold syste ms; and (d) uplift and subsidence events during the middle Tertiary wh ich are probably the result of the continued collision of the European -African plates. After the Early Pleistocene, unlike other terranes wi thin the Mediterranean, an uplift occurred in the northern Hyblean pla teau following the Upper Miocene-Lower Pleistocene massive volcanic ac tivity. This uplift is probably associated with the latest stages of t hrusting along the frontal part of the Maghrebian thrust belt.