Calcareous Ooze

Calcareous ooze is a pelagic sediment in which biogenic calcium carbonate makes up more than 30 percent of the deposit, built from the tests of planktonic foraminifera and the platelets of coccolithophores. It blankets shallower abyssal sea floor above the carbonate compensation depth, the CCD, near 4,000 to 4,500 m, below which calcite dissolution outpaces supply and the ooze gives way to red clay. Dissolution accelerates at the lysocline, around 3,300 to 4,000 m, so the carbonate fraction thins with depth. Globigerina ooze, the foraminiferal variety, is the most widespread, covering nearly half the deep Atlantic and Indian sea floor.