dolomitiseerumist

Dolomitiseerumine is a geological process where the mineral dolomite, calcium magnesium carbonate (CaMg(CO3)2), replaces calcite, calcium carbonate (CaCO3), in existing carbonate rocks. This transformation primarily occurs in limestone and other calcitic sedimentary rocks. The process requires the presence of magnesium-rich fluids, typically seawater or brines, which percolate through the porous limestone.

The exact mechanisms of dolomitisation are still debated, but common theories involve the dissolution of calcite and subsequent precipitation of dolomite, or the direct replacement of calcite by dolomite. This can happen at various temperatures and pressures, from shallow burial environments to deep within the Earth's crust. The rate of dolomitisation can vary significantly depending on factors such as fluid chemistry, temperature, and the permeability of the host rock.

Dolomitisation has profound implications for the properties of the resulting rock. Dolomitic rocks, or dolomites, are generally less soluble than limestones, which affects their weathering patterns and the development of karst landscapes. Furthermore, the pore structure of dolomites can differ significantly from limestones, influencing their potential as reservoirs for hydrocarbons and groundwater. Large petroleum and natural gas fields are often found in porous and permeable dolomite formations. The process is also important in understanding the geological history and diagenetic evolution of carbonate sequences.