Anatomy of seep-carbonates: Ancient examples from the Miocene of the northern Apennines (Italy)

In the Apenninic chain, the abundance and the extent of the outcrops provide a rare opportunity to study the geometry, facies distribution and internal structures of fossil methane-derived carbonates. The present study reports an integrated view of the sedimentology, mineral paragenesis and geochemistry of these seep-carbonates in two different tectono-sedimentary settings: foredeep and satellite basins. The main result of this study is the recognition of 17 facies in the investigated seep-carbonates. The detailed facies and microfacies analysis led to the identification of different structures, which occur in well-defined parts of the carbonate masses. The recurring and broadly similar stratigraphy and facies association from the two considered geological environments is diagnostic of the different stages of seep-carbonate formation and evolution.