dolomitizzate

Dolomitizzazione, or dolomitizzazione in Italian, is a diagenetic alteration of carbonate rocks in which the original calcite in limestone is partially or wholly converted to the mineral dolomite (CaMg(CO3)2). The resulting rock is dolostone, and rocks showing this alteration are described as dolomitized. The term dolomitizzata is the feminine plural form used in Italian to indicate rocks that have undergone dolomitization.

Most dolomitization involves replacing calcium with magnesium in the carbonate lattice, driven by magnesium-rich pore fluids. This can occur by direct replacement of calcite by dolomite, by recrystallization of the carbonate framework, or by a combination of both. Fluids moving through the rock—often along fractures, faults, or in porous channels—facilitate the exchange, and the process can take place during burial diagenesis or in shallower, evaporitic environments.

Geological significance varies: dolomitization can alter porosity and permeability in complex ways. Dolostone may exhibit higher porosity in some cases due to dissolution-enhanced voids, but cementation and overprinting diagenetic textures can reduce pore space in others. The heterogeneity of dolomitized rocks makes them important but challenging to predict as reservoir rocks in hydrocarbon systems.

Isotopic and trace-element evidence, including shifts in oxygen and carbon isotopes and fluid inclusion data, are commonly used to diagnose dolomitization and to infer the characteristics of the dolomitizing fluids, such as temperature and composition. Dolomitization is a widespread diagenetic process observed in ancient and modern carbonate settings, influencing rock interpretation, reservoir quality, and diagenetic histories.