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Convolute bedding-pillow horizons-of likely seismic origin are identified in a bioclastic carbonate succession, the Guadagnolo Formation, in the central Apennine Mountains of Italy. These sediments, which were deposited in a carbonate-ramp environment, are from Burdigalian to Langhian (Relizian) in age. The lower part, about 500 m thick, consists of marlstones, marly limestones, and calcarenites, representing cyclic, shallow-water, coarsening-upward sequences. The second part, about 100 m thick, is dominated by prograding bodies of calcarenites. The horizons containing the pillow beds are in the topmost of the lower part, about 30 m below the base of the overlying calcarenites. They are present at the same stratigraphic position from the Prenestini to the Ruffi Mountains across a distance of about 20 km. Pillows, 20 cm to more than 1 m thick, are present in all the deformed layers and consist of marly calcarenites, which differ texturally from the enclosing matrix. They are regarded as the product of deformation ensuing from liquefaction of a denser layer overlying a lighter, silty layer that is richer in clay.These structures are interpreted to reflect liquefaction processes induced by seismic shocks, and they correlate well with coeval Miocene tectonism in this sector of the Apennines.

The Authors report spongolitic faciès of the Lower Miocene identified at kefaliinia and Ithaki and discuss the significance of these facies as well as of a diatomaceous épisode of the same age found at Zakynthos. The spongolitic or diatomaceous facies are referred to the volcanism which extended over the entire Mediterranean basin in the Lower Miocene but their occurence and distribution are related to local settings. Spongolitic facies develop on areas wheré pelitic sediments are interbedded with calcareous clastic resediments derived from gravity flows, both in Ionian Islands and Spain and Central Apennines. So their presence seems to be suitable for paleogeographic reconstruction, since they suggest the existence of slopes around carbonate platform edges with a high rate of production and reworking of calcareous clastic materials.

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