Research paperCorrelating shelf carbonate evolutive phases with fluid expulsion episodes in the foredeep (Miocene, northern Apennines, Italy)

•We correlate carbonate shelf in wedge-top basin with seep episodes in the foredeep.•Seep-carbonates are useful stratigraphic markers and climate-tectonic sensitive proxy.•Evolutionary phases of Miocene temperate-type carbonates are outlined.•Synsedimentary tectonics control the onset and crisis of carbonate sedimentation.•Terrigenous discharge and Mi3b climate cooling favored the drowning of the shelf.

In the Miocene of the northern Apennines of Italy, evolutionary phases of shallow-water carbonates in wedge-top basins are coeval with methane-rich fluid expulsion episodes in the inner foredeep. We identified four main correlative events, primarily controlled by synsedimentary tectonics, sediment input and climate cooling: 1) a Burdigalian tectonic phase determined the onset of shelfal sedimentation in wedge-top areas and is correlated with an important episode of fluid expulsion in marly sediments of the inner foredeep (Croce di Moggiona seep-carbonates); 2) the decrease of shelfal carbonate production and the increase of detrital input in the Early Langhian correspond with a second important episode of seep-carbonate precipitation in the inner foredeep (Castagno d'Andrea); 3) the demise of the carbonate shelf and the coeval expulsion of methane-rich fluids in the inner foredeep (Vicchio and M. Citerna seep-carbonates) at the Langhian/Serravallian boundary approximate the Mi3b cooling event. The lower temperatures, associated with increased siliciclastic weathering, led to the crisis of shallow-water carbonate production whereas the pressure drop due to the eustatic fall may have triggered the gas-charged fluid expulsion; 4) the tectonic-related uplift of frontal sectors of the wedge-top basin led to the wide erosion of the Burdigalian-Langhian carbonates and caused the precipitation of authigenic seep-carbonates (Deruta seep) both in the slope and the adjacent foredeep.