Zementation

Zementation, in geology, is the diagenetic process by which mineral precipitates bond sediment grains together, forming a solid rock. It is the German term for cementation; in English literature the term is cementation. It occurs during burial when pore waters become supersaturated with minerals such as calcite, quartz (silica), dolomite, or iron oxides.

The cementing minerals precipitate from pore fluids and bind at grain contacts, along pore throats, or within pore spaces, producing lithified rock. Forms include calcite cement, silica (quartz) overgrowths or opal/chert cement, dolomite cement, and iron oxide cements. Cementation may occur alone or with other diagenetic processes like compaction.

The degree and type of cementation strongly affect porosity and permeability. Normally, cementation reduces porosity by filling pore spaces, but in some cases cement may create connected pathways that preserve or enhance permeability. It occurs widely in sandstones, siltstones, and carbonates, with variations depending on diagenetic history, burial depth, fluid composition, temperature, and time.

The study of Zementation uses petrography, thin section microscopy, SEM, cathodoluminescence, isotope geochemistry, and fluid inclusion analyses to interpret diagenetic history and reservoir quality. It has practical significance for hydrocarbon reservoirs, groundwater aquifers, and construction material quality.