Diagenetic processes along a basin-wide marker bed as a function of burial depth

The Contessa megabed is a basin-wide turbidite bed in the Marnoso-arenacea Formation (Miocene) of the northern Apennines (Italy). It has a mixed siliciclastic/carbonatoclastic composition and was derived from the southern end of the elongate, NW-SE-trending Periadriatic foreland basin. Heavy-mineral contents of fifteen Contessa samples taken across the whole outcrop area vary systematically. Petrologic parameters of mostly siliciclastic sandstone beds stratigraphically close to the Contessa megabed and derived from the Alps to the northwest (non-Contessa' samples) depict similar trends in spite of their different provenance. These areal differences in mineralogy are interpreted to result from varying degrees of diagenesis due to differential sedimentary/tectonic load in the asymmetrical Periadriatic basin. -from Authors