AUTHORS: Riva A., Preto N., Marian M.
AAPG 2013, Barcelona
The Cretaceous margin of the Adriatic Carbonate Platform is considered one of the possible targets for exploration in the Adriatic sea, with some successful results in the Montenegro area (JJ3 well). The northwestern margin of the Adriatic carbonate platform is outcropping in the Cansiglio massif of North-Eastern Italy. This area is historically well-known, but geological studies applying modern methods of sedimentology and stratigraphy are missing.
We started mapping the area, focusing on the relationships between the shallow water platform and its slope, trying to reconstruct the pattern of the margin and the facies distribution across a depositional profile.
This platform is characterized by a gravitational slope with the angle decreasing trough time, with megabreccias and turbidites directly onlapping the shallow water facies of the platform interior. Locally oolitic shoals and metazoan reefs are preserved at the margin and upper foreslope. Since Cenomanian, the platform interior switched from mud-dominated to grain dominated, boasting the shedding of grainstone and a strong slope progradation. The margin is often karstified, with high-frequency cyclic exposure events. Small fault-bounded anoxic intraplatform basins with fishes and fossil plants document synsedimentary tectonics within the platform interior.
The facies distribution identifies the external marginal and the foreslope areas, characterized by grainstone shoals and low-angle clinoforms, as the best potential reservoir in the system. These facies belts are normally unaffected by meteoric diagenesis. Outcrop analogue studies at Cansiglio contribute to the interpretation of seismic lines in the Adriatic subsurface and may help to disentangle current uncertainties in the seismic facies interpretation.