The Role of the Syndepositional Cementation and the Microbial Boundstone Accumulation in the Depositional Dynamics of the Triassic Platforms of the Italian Dolomites

The understanding of the carbonate platform reservoirs can be improved through the comparative analysis of outcropping analogous, such as the Triassic ones from the Italian Dolomites (Fig. 1). The study of the different platform generations outcropping in this region is particularly worthy in clarifying the dynamic relationships between the changing carbonate production and the depositional architecture. This analysis suggests that the sedimentary composition of the platforms can be inferred from their depositional geometry and vice versa, because of the strong genetic linkage of these two depositional features. This relationship shows up while analysing the clinostratified slope bodies, forming the largest volume of the Anisian, Ladinian and Carnian platforms outcropping in this portion of the Italian Southern Alps. The study limestones are dominated by large volumes of calcareous cements and microbial boundstones, both associated with micro-dispersed organic matter, whereas the calcareous metabionts generally form only a tiny portion of the rock mass, despite their high taxonomic diversity. The primary sediment composition and depositional geometry indirectly affected the present-day rock porosity and permeability, by influencing the carbonate diagenetic evolution. Even if quantitative estimates are still beyond our possibilities, the predictive potential for the 3D subsurface interpretation is already clear. The strongly peculiar features of these Triassic platforms however suggests that care has to be used in applying this data to the interpretation of reservoirs from other chronological intervals.