(dolomite-rich), are unique because they are often "born, not made". Unlike clastic rocks (like sandstone) that form from the debris of other rocks, the majority of carbonates originate through the biogenic activity
The origin of carbonate sedimentary rocks is an intricate interplay of biological innovation, global ocean chemistry, and post-depositional diagenesis. From their birth via microbial or skeletal precipitation in clear equatorial waters to their structural transformation deep within planetary crusts, carbonates stand as dynamic, evolving systems that continuously record the shifting baseline of Earth's biosphere and environment. origin of carbonate sedimentary rocks pdf new
Occurs at or just below the seafloor. Key processes include microbial boring, which converts grain margins into fine-grained micrite (micritization), and the precipitation of isopachous aragonite fibrous cements or high-magnesium calcite rinds in high-energy settings. Meteoric Diagenesis (dolomite-rich), are unique because they are often "born,
[ SHALLOW RAMPS & PLATFORMS ] │ ┌────────────────┴────────────────┐ ▼ ▼ [ Tropical Factory ] [ Cool-Water Factory ] • Photozoan assemblages • Heterozoan assemblages • Aragonite & High-Mg Calcite • Low-Mg Calcite dominated • Rapid rimmed geometries • Ramp/homoclinal geometries 1. The Tropical (Photozoan) Factory Occurs at or just below the seafloor
The global mineralogical shift between "Aragonite Oceans" and "Calcite Oceans" is governed by the molar Mg/CaMg/Ca ratio of seawater: Mg2+Mg raised to the 2 plus power
Carbonates can also precipitate directly from seawater, a process that was likely much more common in Earth's past. This inorganic origin is responsible for several distinctive limestone types:
Recent work (2020–2025) has moved beyond the standard "Chalk, Limestone, Dolomite" classification. Here are the three paradigm-shifting updates.