Strutture sedimentarie deformative in calcareniti di spiaggia plio-pleistoceniche delle Murge

Soft-sediment deformation structures are observed at Cala Corvino locality, along the Adriatic coast, close to Monopoli town (soulhern lIaly). Here Plio-Pleistocene calcarenitic deposits transgressively overlie on Crelaceous limestone; the structures occur al the bottom of these deposits and involve a gravelly level. The structures are vertically downward elongated and have metric scale; they are morphologically similar to the branching pillar and pocket structures, described by Postma (1983). The genesys of these soft-sediment ddormation structures required a trigger of a deformation mechanism in a driving force system (sensu Owen, 1987). At Cala Corvino the driving force system was the reversed density gradient (sensu Anketell, Cegla e Dzulinski. 1970), which was detcrmined by the overlaying of a gravel level on very permeable sands. The deformation mechanism was the liquefaction of these sands which caused the sinking of the gravel and the development of sag and down-sink drop structures (sensu Anketell l't al.). We can't exclude the trigger of liquefaclion was a strong storm or a tsunamis, but the Cala Corvino soft-sediment deformation structures show big dimension and similiraty with other ones developed in driving force system in which the trigger was a seismic shock.