Submarine diagenetic products on the sediment-starved Gorgona slope, Tuscan Archipelago (Tyrrhenian Sea).

Various types of submarine diagenetic products occur at bathyal depths (>300 m) along the Gorgona slope, eastern Tyrrhenian Sea. Bottom sampling during cruise LM-99 of the R/V Urania recovered pristine to diagenetic altered shells (including steinkern) and phosphatized/carbonate hardgrounds. Chemical maps (Al, Ca, Si, S, Fe, P) are provided to characterize these diagenetic products. A peculiar category of steinkern (black molds) of benthic invertebrate calcareous shells is the result of pervasive substitution by phosphomicrite and glaucony. Chemical precipitation and mineral replacement at the expense of pelagic sediment and skeletal carbonates took place under prolonged conditions of exposure at the seawater-sediment interface.