The strata of the Orfento Formation are characterized by high depositional porosity (average 20-30%), which reflects distribution of depositional facies. Primary porosity is increased by moldic porosity (average 15-20%), selectively on aragonitic grains. Early meteoric diagenesis was responsible for aragonite dissolution and precipitation of calcite cements. Calcite cementation is scarce and has a very heterogeneous distribution. The occurrence of moldic porosity and calcite cements is maximum in the progradational units and was controlled by stratigraphy, as related to minor-order unconformities, and by facies distribution. Cathodoluminescence patterns and stable isotopes suggest that precipitation of calcite cement occurred in localized freshwater systems, associated with minor-order erosional unconformities within the progradational unit.

The lower and upper supersequence boundaries were both associated with prolonged subaerial exposure (ca. 5-6 and 8-10 m.y., respectively), but responded differently with respect to porosity formation and preservation. Beneath the lower supersequence boundary, fabric-selective aragonite dissolution and extensive meteoric calcite cementation decreased the porosity. Cathodoluminescence patterns and stable isotopic compositions of the cements indicate precipitation in a stable freshwater system. The