Some of the Neogene to Quaternary sedimentary successions cropping out in the southern Italy orogenic belt exhibit distinct stratigraphic intervals of mixed, silici-bioclastic arenites. These deposits represent bay- and strait-fill successions that accumulated during tectonically-driven, rapid transgressions in peripheral marine basins of the central Mediterranean, experiencing microtidal conditions similar to those presently existing in the Mediterranean Sea. The Upper Miocene to Middle Pleistocene successions of Basilicata, Calabria and NE Sicily, show laterallyaccreted, cross-strata of mixed composition, with the siliciclastic fraction derived from either sedimentary or metamorphic rocks and the bioclastic fraction produced by an in situ or near situ heterozoan factory. Tidal cyclicity of semi-diurnal and diurnal to monthly and yearly periodicities has been detected in the studied deposits, where tidal bundling is revealed by the rhythmic alternation of siliciclastic and bioclastic set of laminae, repeated according to different cycles. This rhythmic signature appears to be more evident where randomly-occurring processes, such as waves, storms and currents, were mitigated by engulfed or strait palaeo-settings. Palaeo-bays preserved short-term tidal cycles in shoreface to offshore-transition mixed deposits because hydrodynamically isolated from open marine conditions and therefore subjected to tidal influence only during fair-weather periods. On the contrary, palaeo-straits recorded tidal cyclicities of longer duration in deeper mixed deposits subjected to steady tidal currents.
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|Titolo:||Tidal signatures in Neogene to Quaternary mixed deposits of southern Italy straits and bays|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||1.1 Articolo in rivista|