Diatomaceous Ooze

Diatomaceous ooze is a siliceous pelagic sediment in which opaline silica from diatom frustules makes up more than 30 percent of the deposit. It forms a subset of siliceous ooze and concentrates beneath high-productivity surface water, mainly the Antarctic and subantarctic belt of the Southern Ocean and the North Pacific, where dissolved silica supply is high and competing carbonate falls below the CCD. Unlike calcite, opal-A has no compensation depth, so diatomaceous ooze accumulates on deep sea floor where calcareous ooze cannot survive. Sedimentation rates run a few millimeters to centimeters per thousand years.