oolite

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oolite

(ō`əlīt, ō`ō–), rock composed of small concretions, usually of calcium carbonate, containing a nucleus and clearly defined concentric shells. In the British Isles oolitic limestone is characteristic of the middle and upper Jurassic, which was formerly termed the Oolite on this account.

Oolite

 

(according to some sources, oolith), a spheroidal or ellipsoidal formation consisting of oxides and silicates of iron and manganese and of calcite, dolomite, aragonite, rhodochro-site, leptochlorite, and other minerals. Oolites range in size from several microns to 15–25 mm. Oolites larger than 2–5 mm are called pisolites. In the center of an oolite there is usually—but not always—a grain of sand or a fragment of the calcareous shell of some organism, around which thin layers of the precipitating substance accrete; as a result the structure of oolites is usually concentric-botryoidal. Oolites with radial and complex structures (combinations of concentric-botryoidal and radial structures) are also found. Oolites form in seawater and warm springs as a result of colloid-chemical and biochemical processes. Ferruginous oolites are a variety of iron ore.

REFERENCE

Shvetsov, M. S. Petrografiia osadochnykh porod, 3rd ed. Moscow, 1958.

V. A. GROSSGEIM

oolite

[′ō·ə‚līt]
(petrology)
A sedimentary rock, usually a limestone, composed principally of cemented ooliths. Also known as eggstone; roestone.

oolite

A granular limestone, each grain of which is more or less spherical and made up of concentric coats of carbonate of lime formed around a nucleus.

oolite

any sedimentary rock, esp limestone, consisting of tiny spherical concentric grains within a fine matrix
References in periodicals archive ?
The K3 dolomites are gray to dark gray, dark brown, brittle, fine crystalline, slightly argillaceous, hard to moderately hard, locally calcareous, micro-sucrosic, traced with oolites and pelloids and characterized by poor to visible porosity.
Each cycle began with deposition of carbonate pelletal mud, micrite, followed upward by fossiliferous calcarenties and an upward shoaling oolite bar.
Figure 3 illustrates this phenomenon and the controlling factors for the well-studied Cenozoic limestones and dolostones from Florida and the Jurassic Smackover oolite reservoirs in the southern United States.
The Fusselman Formation consists of two major lithostratigraphic units, a thin basal, Late Ordovician (Hirnantian) oolite that is overlain unconformably by a thicker Llandoverian (Silurian) complex of carbonates.
0 m is represented by interbedded reddish-brown to varicoloured, bioturbated marlstones and argillaceous limestones containing an interlayer with ferruginous (iron) oolites at a depth of 293.
No oolites have been found at Pilot Knob Hematite but the similarity of the Pilot Knob ores to the fine grained ores at Cedar Hill which are undoubtedly of sedimentary origin, strongly supports our past assertions that Pilot Knob Hematite is of sedimentary origin and not of hydrothermal replacement origin.
However, Minagish oolites have proved to contain high-sulphur hydrocarbons with toxic hydrogen sulphide.
Phosphorite concretions, phosphatic oolites and phosphatic discontinuity surfaces are recorded mainly in the lower part of the Ordovician carbonate succession in Estonia.
Before the Gulf crisis it was producing 40,000 b/d, compared to 51,000 b/d in 1979, from Minagish Oolites of the Lower Cretaceous Ratawi.
Before the Gulf crisis it was producing at the rate of 40,000 b/d, compared to 51,000 b/d in 1979, from Minagish Oolites of the Lower Cretaceous Ratawi.
the Bara Oolite Member of the Halla Formation in Gotland (Calner & Sall 1999) or the Limberlost oolite of the Cincinnati Arch (Brett et al.