The peculiar methane-derived carbonates enclosed in pelitic and marly deposits of the Miocene inner foredeep in the northern Apennines are useful tracers for an evaluation of tectonic and sedimentary processes in the Miocene shelf-slope-basin system in a compressive geodynamic context. The carbonate precipitation is related to emissions of hydrocarbon-rich fluids and it is controlled by: - tectonic events (tectonics constrains the plumbing system, with faults and fractures serving as conduits and channelling water and methane up to the seafloor); - climatic events (carbonate formation seems to correlate with cold periods and sea-level low-stand). The correlation between methane-derived carbonates and climate during the Miocene in the northern Apennines has been suggested by recent results (Fontana et al,. 2013) of a sedimentological and biostratigraphic study of seep-carbonates and the enclosing hemipelagic Vicchio marls. The study suggests a correlation between the carbonate precipitation and the middle Miocene cooling event (Mi3b). The ascent and emission of methane-rich fluids may have been triggered by the pressure drop due to the eustatic fall. A detailed study of the δ18O record of carbonates and δ13C of total organic matter in enclosing marls has been performed in order to verify a correlative trend in correspondence of the climatic cooling event. A palaeocological study has allowed to check the influence of these stressed environmental conditions on benthic foraminifera assemblages. Therefore morphological, textural, biostratigraphic, geochemical studies could allow to characterize seep-carbonates related to climatic event. Results of this study could contribute to the reconstruction of transgressive-regressive events in the adjacent temperate-type carbonate platforms, as well as the definition of modes and rates of the demise of carbonate deposition and the onset of clastic sedimentation. The identification of cold phases and lowering of sea level in slope-basinal deposits and their detailed timing, may be an useful and innovative tool for correlation with coeval shallow-water successions, and for the reconstruction of the evolution of the Miocene platform-basin system in the compressive setting of the northern Apennines.
Cold-seep carbonates as tracers for the evolution of the platform-basin system in the Miocene of the northern Apennines (Italy) / Salocchi, AURA CECILIA; Fontana, Daniela; Conti, Stefano; Fioroni, Chiara; Grillenzoni, Claudia. - ELETTRONICO. - 1:(2014), pp. 601-601. (Intervento presentato al convegno Sedimentology at the crossroads of new frontiers tenutosi a Geneva nel August 18-22).