Biocalcarenite and mixed cool-water prograding bodies of the Mediterranean Pliocene and Pleistocene: archietcture, depositional setting and forcing factors

Plio-Quaternary basinward-prograding heterozoan carbonate wedges with seaward-dipping, steep clinoforms and significant along-strike extension, are common both on land and along the submerged margins of the Mediterranean area. They developed as distally steepened ramps on storm-dominated, relatively steep-gradient margins, commonly controlled by tectonics. Dispersal of the skeletal hash was mainly due to storm-driven downwelling and geostrophic currents, changing into gravity flows down the clinoformed ramp margin. Due to active winnowing and bypass in the shallow-water settings, biocalcarenite ramps were entirely detached from the shoreline. Sequence-stratigraphic architecture of cropping out prograding bodies indicates the presence of internal unconformity surfaces bounding shingled units with sigmoidal to oblique clinoforms. Similar wedges identified by seismic survey on the margins of the Tyrrhenian Sea generally show a back-stepping pattern, with the deeper-located wedges related to the last lowstand and the subsequent wedges reflecting episodic stillstands during sealevel rise. A critical role in determining the efficiency of the carbonate factory is thought to have been played by the increase in the strength of atmospheric and marine circulation which accompanied the long-term climatic change affecting the Mediterranean area since 3.1 Ma, especially during cooler to colder stages.