carbonaterock

Carbonate rock refers to sedimentary rocks composed primarily of carbonate minerals, chiefly calcite (CaCO3) and dolomite (CaMg(CO3)2). The two principal rock types are limestone, which is dominated by calcite, and dolostone, dominated by dolomite. Other carbonate rocks include biogenic limestones rich in skeletal material and chemical precipitates such as travertine and ooid-rich deposits.

Formation: Carbonate rocks form in marine and lacustrine settings through two main pathways. Biochemical processes build limestone from shell and planktonic debris; chemical precipitation can also occur directly from water in suitable conditions. Diagenesis, including cementation, compaction, and dolomitization, can modify composition and texture after deposition.

Distribution and features: They are widespread and form extensive sedimentary sequences in many regions. Carbonate rocks commonly exhibit porosity and permeability in some settings, making them important hydrocarbon reservoirs and groundwater aquifers, while others are dense and relatively impermeable. Karst processes—dissolution by slightly acidic water—produce caves, springs, and sinkholes in carbonate terranes.

Economic importance: Limestone and marble are important building materials; limestone is a vital source of lime and cement. Dolostone, dolomite, and related products have various industrial uses, including aggregates and specialty minerals.

Fossil content and carbon cycle: Carbonate rocks frequently host fossils and preserve paleoenvironmental information. They also play a major role in the long-term carbon cycle, forming a substantial carbon reservoir through burial and release during weathering and dissolution.

See also: calcite, dolomite, limestone, dolostone, karst, sedimentary rocks.