carbonatées

Carbonatées (carbonate rocks) are sedimentary rocks dominated by carbonate minerals, principally calcite and dolomite. They cover a substantial portion of the Earth’s continental crust and play a central role in the global carbon cycle. Most carbonates form in shallow marine settings where calcium and carbonate ions precipitate from seawater or accumulate as debris from organisms such as corals, foraminifers, and coccolithophores. Over time, these sediments are lithified into limestone, dolostone, chalk, and related rocks; carbonate cementation and diagenetic alteration can modify their texture and composition. Metamorphic equivalents, such as marble, arise when carbonate rocks are subjected to heat and pressure.

Common carbonate rocks include limestone (predominantly calcite), dolostone (predominantly dolomite), chalk (micritic limestone rich in microfossils), and coquina (bioclastic gravel). Textures range from crystalline to fine-grained to fossiliferous, and porosity varies widely, influencing their hydraulic and reservoir properties. Karst processes—dissolution by weak acids in groundwater—shape many landscapes and create features such as caves and springs.

Economically, carbonate rocks are important as sources of lime, cement, crushed stone, and aggregate. They host major hydrocarbon reservoirs when porous and permeable, and they offer potential for groundwater storage and CO2 sequestration. Carbonatées thus intersect geology, hydrology, industry, and climate, reflecting both Earth’s history and present-day processes.