The lysocline is the depth in the ocean dependent upon the carbonate compensation depth (CCD), usually around 5 km, below which the rate of dissolution of calcite increases dramatically because of a pressure effect. While the lysocline is the upper bound of this transition zone of calcite saturation, the CCD is the lower bound of this zone.
CaCO content in sediment varies with different depths of the ocean, spanned by levels of separation known as the transition zone. In the mid-depth area of the ocean, sediments are rich in CaCO, content values reaching 85–95%. This area is then spanned hundreds of meters by the transition zone, ending in the abyssal depths with 0% concentration. The lysocline is the upper bound of the transition zone, where amounts of CaCO content begins to noticeably drop from the mid-depth 85–95% sediment. The CaCO content drops to 0% concentration at the lower bound, known as the calcite compensation depth.
Shallow marine waters are generally supersaturated in calcite, CaCO, because as marine organisms (which often have shells made of calcite or its polymorph, aragonite) die, they tend to fall downwards without dissolving. As depth and pressure increases within the water column, calcite solubility increases, causing supersaturated water above the saturation depth, allowing for preservation and burial of CaCO on the seafloor. However, this creates undersaturated seawater below the saturation depth, preventing CaCO burial on the sea floor as the shells start to dissolve.
The equation Ω = [Ca] X [CO]/K' expresses the CaCO saturation state of seawater. The calcite saturation horizon is where Ω =1; dissolution proceeds slowly below this depth. The lysocline is the depth that this dissolution impacts is again notable, also known as the inflection point with sedimentary CaCO versus various water depths.