The two most common carbonate rocks are limestone, composed primarily of calcite or aragonite (CaCO3), and dolostone, composed of dolomite (CaMg(CO3)2). The origin of these rocks is often described as autochthonous, meaning they are "born, not made." While a sandstone is composed of grains transported from a distant mountain range, the grains in a limestone usually originate within or very near the basin where they are deposited. Biological Origins: The Carbonate Factory
: The most common origin is the activity of living organisms . Marine life—including corals , mollusks , and foraminifera —extracts calcium and carbonate ions from seawater to build shells and skeletons . When these organisms die, their remains accumulate as skeletal grains. origin of carbonate sedimentary rocks pdf extra quality
For geoscientists, a standard PDF is insufficient. implies: The two most common carbonate rocks are limestone,