Diatomaceous Ooze

diatomaceous ooze [¦dī·ə·tə¦mās·shəs ′üz]

(geology)

A pelagic, siliceous sediment composed of more than 30% diatom tests, up to 40% calcium carbonate, and up to 25% mineral grains.

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Diatomaceous Ooze 

sediment on the bottom of present-day oceans, seas, and lakes, consisting primarily of the shells of diatoms. It is distinguished by a high content of amorphous silica (up to 70 percent). In addition to opal, diatomaceous ooze includes various quantities of argillaceous, detrital, and carbonaceous mineral particles.

In moist form, diatomaceous ooze is a soft, fine-grained sediment, rich in interstitial water (up to 80–90 percent of the volume), that is not sticky to the touch. In pure varieties it has a light yellowish gray color. It forms in the oceans and seas in areas of high production of diatomaceous plankton and low supply of sedimentary material of other origin. Diatomaceous oozes are most common in the waters of the moderate latitudes of the southern hemisphere, where they are observed in a solid belt around Antarctica. Freshwater diatomaceous oozes form on the bottom of some lakes (for example, Baikal). In fossilized form, diatomaceous ooze becomes the sedimentary rock diatomite.

REFERENCES

Bezrukov, P. L. “Donnye otlozheniia okhotskogo moria.” Tr. In-ta okeanologii AN SSSR, 1960, vol. 32.
Osadkoobrazovanie v Tikhom ekeane. Moscow, 1970. (Tikhii okean, vol. 6, books 1–2.)

I. O. MURDMAA