calcáreos

Calcáreos, or calcareous rocks, are sedimentary rocks dominated by carbonate minerals, primarily calcite (CaCO3) and, in some rocks, dolomite (CaMg(CO3)2). They form by accumulation of carbonate sediments from biological activity, precipitation from supersaturated waters, or both.

The major types include limestone (predominantly calcite), dolostone (dolomite), chalk (fine-grained microfossils), travertine (precipitated near springs), and marl (clay-rich carbonate). Coquina and fossiliferous limestone are other common varieties.

Formation and diagenesis: deposition occurs in marine and occasionally non-marine environments; lithification proceeds through compaction and cementation; post-depositional alteration such as dolomitization can convert limestone to dolostone.

Properties and landscapes: porosity and permeability vary; dissolution by acidic water creates karst features such as caves, sinkholes, and underground drainage; carbonate rocks host important groundwater and hydrocarbon reservoirs.

Uses: cement production from limestone and dolostone, lime for agriculture and industry; building stone and decorative materials; filler and pigment in various products.

Paleontological and climate records: carbonate rocks commonly contain fossils and preserve isotopic and microfossil data that help reconstruct ancient oceans, temperatures, and sea levels.

Global distribution and significance: calcareous rocks are widespread, forming major outcrops in many regions; their chemical reactivity makes them important to landscapes, economies, and geologic history.