Calcitic oolite

Calcitic oolite A pavement of calcitic ooids formed by continuing precipitation of calcium carbonate between the calcitic ooids. 

Oolite A hydrogenous precipitate commonly found in carbonate sediments of continental shelves located in the tropics. They are composed primarily of calcium carbonate and are thought to be an abiogenic precipitate formed from warm seawater supersaturated with respect to calcite and aragonite. 

Bedded Ores. These often are composed of oolites of hematite, sidcrite. iron silicate, or less commonly, limonitc in a matrix of sideriie. calcite. nr silicate. They have a wide geographic distribution associated with cither sedimentary rocks. They sometimes contain fossils and line grains of sand. They nften have a fairly high phosphorus content and may he self-fluxing. 

Sellwood, B. W., Wilkes, M. James, B. 1993. Hydrocarbon inclusions in late calcite cements migration indicators in the Great Oolite Group, Weald Basin, S. England. Sedimentary Geology, 84, 51-55. 

Oolitic limestones (or ooliths) are made up of tiny spherical grains (known as ooids) of 1 mm or less in diameter, precipitated by algal action in turbulent waters and cemented in calcite. Under a hand lens, they have the appearance of fish roe. 

Oolitic limestone Clastic Rounded calcite ooliths bounded by a calcite cement. Can be slightly dolomitized. 

Modulated microstructure occurs in calcite, as well as in dolomite, and was first identified in Jurassic oolitic limestone by Gunderson and Wenk (1981). However, chemical analysis of the oolitic limestone showed no compositional differences between areas with the modulation and those without. Since, the modulations could not be the result of compositional fluctuations of Ca-Mg as in dolomite, Gunderson and Wenk (1981) hypothesised that the rotational disorder of CO3 groups that occurred during phase transformation of aragonite to low-magnesium calcite might cause the modulations. 

The phosphorites consist of carbonate-fluorapatite mixed with varying amounts of quartz silt, clay minerals, calcite, dolomite, chert and carbonaceous matter. Most of the phosphate occurs as pellets with amounts of oolites, intraclasts, scales, phosphatic shells and replaced skeletal grains. The pellets are cemented with dolomite, calcite, phosphate or, rarely, chert. Some phosphorite beds are composed of phosphate mud. There is a general decrease in size and abundance of intraclast fragments and an increase in carbonaceous content in the phosphorite beds toward the west. These characteristics, plus the close association of phosphorites with cherts and... 

---