Facies and early dolomitization in Upper Albian shallow-water carbonates of the southern Apennines (Italy): paleotectonic and paleoclimatic implications

Thick successions of Cretaceous carbonates in the southern Apennines of Italy are of great economic interest since they host important aquifers and huge hydrocarbon accumulations. The reservoir of the Val d???Agri and Tempa Rossa oilfields (in the subsurface of Basilicata) consists of Upper Cretaceous rudist-rich lime- stones passing downward into mid-Cretaceous dolomitized limestones of restricted platform facies. Upper Albian- Lower Cenomanian dolomitized carbonates exposed in the Sorrento Peninsula and in the Cilento Promontory, part of the Apennine Carbonate Platform, represent a good surface analogue for the lower part of the reservoir. They are composed of meter-thick beds of stratabound dolomite and shallowing-upward cycles of restricted platform limestones capped by silicified evaporites and marly levels. Field relations, petrography, and geochemistry implicate the reflux of penesaline waters as the most probable dolomi- tization process. High-frequency climatic variability between dry and wet phases can explain the formation of evaporites, which are coeval with karstic bauxites in other sectors of the southern Apennines. The dolomitized car- bonates of the Sorrento Peninsula pass laterally into do- lomitized breccias, which were the result of local tectonic collapse of the platform. This is further evidence of mid- Cretaceous syn-sedimentary tectonics that in other areas of the Adria passive margin contributed to the formation of intraplatform basins where source rocks accumulated.