Found in latitudes >30°, where waters are cooler and often undersaturated with respect to aragonite.
The story of a carbonate rock does not end with its deposition. After the sediment is laid down, it begins a long journey of physical, chemical, and biological changes known as . These processes transform loose carbonate sediment into solid rock ( lithification ) and can dramatically alter its original texture and mineralogy.
Shallow-water carbonates are robust indicators of tropical to subtropical, clear water conditions. origin of carbonate sedimentary rocks pdf extra quality
Occurs when rain or fresh groundwater infiltrates the sediment (often during sea-level drops). It is highly aggressive toward unstable minerals. Aragonite and HMC dissolve, supplying calcium for the precipitation of stable LMC blocky equant cements. This zone creates extensive vuggy and moldic secondary porosity.
Carbonate sedimentary rocks, primarily and dolostone , are unique because they are mostly intrabasinal —meaning the sediment is produced within the same basin where it is deposited, often by biological processes. Unlike siliciclastic rocks (like sandstone) that come from land erosion, up to 90–95% of carbonate grains are biogenic in origin. 1. Primary Sources of Carbonate Material Carbonate sediments originate from three main pathways: 6. Carbonate Sedimentary Rocks Found in latitudes >30°, where waters are cooler
. From microscopic plankton to massive coral reefs, these creatures extract calcium and carbonate ions from seawater to build shells and skeletons. When these organisms die, their remains accumulate on the ocean floor, creating layers of biogenic sediment Chemical Precipitation
Ca2++2HCO3−⇌CaCO3↓+CO2↑+H2OCa raised to the 2 plus power plus 2 HCO sub 3 raised to the negative power is in equilibrium with CaCO sub 3 down arrow positive CO sub 2 up arrow positive H sub 2 O The saturation state ( Ωcap omega It is highly aggressive toward unstable minerals
Rearrangement of grains, breaking of fragile bioclasts, and dewatering of fine muds.
2HCO3−⇌CO32−+H2O+CO2↑2 HCO sub 3 raised to the negative power is in equilibrium with CO sub 3 raised to the 2 minus power plus H sub 2 O plus CO sub 2 up arrow
To standardize text descriptions and geological mapping, two primary classification schemes are utilized globally. Both capture the depositional texture, energy regimes, and component ratios of limestones. The Folk Classification (1959, 1962)