dedolomitization

Dedolomitization is a geological process that occurs when dolomite, a magnesium calcium carbonate mineral, is altered. This alteration typically involves the removal of magnesium from the dolomite structure and its replacement by calcium. The most common mineral product of dedolomitization is calcite, a calcium carbonate mineral. This process can occur through various mechanisms, often involving interaction with circulating fluids.

One common way dedolomitization happens is when acidic groundwater or pore fluids percolate through a dolomite formation. These fluids can dissolve the dolomite, and under certain conditions, the dissolved magnesium is removed, leaving behind a residue enriched in calcium, which then recrystallizes as calcite. Another mechanism involves the presence of other minerals that can react with dolomite, facilitating the removal of magnesium.

Dedolomitization is significant in several geological contexts. It can affect the porosity and permeability of carbonate rocks, influencing groundwater flow and hydrocarbon reservoirs. In sedimentary environments, it can lead to the formation of secondary porosity, as the replacement of dolomite by calcite can involve a volume change, creating or enlarging pore spaces. Understanding dedolomitization is also important in the study of diagenesis, the physical and chemical changes that occur in sediments after deposition. The extent and nature of dedolomitization can provide clues about the history of fluid-rock interaction within a rock formation.