Diagenetic processes of dolomitization and calcitization have been recorded from the upper Maastrichtian -lower Danian shallow-marine carbonate rocks at Quecedo. Dolomitization is associated to a first order sequence boundary, evolved from upper to lower and affected very shallow marine sediments. A diagenetic sequence from evaporative, to marine and meteoric mixing ambients, to a later freshwater generalized input can be inferred from both the study of micro textures and cathodoluminescence observations