Oolitic limestone

Oolitic limestone is composed of small rounded grains of CaCO, precipitated in concentric laminates around a nucleus of CaCO or siUca. It is frequently very pure but may be impure. 

Fig. 2.7.4 f-T2 spectrum for oolitic limestone. The dashed lines in B are for f = T2 and Ti = AT2. The solid thick line is theoretical behavior of the sum of surface and bulk contributions to Ti and T2. The inset is a 30-micron thin-section micrograph of the oolitic rock. The... 

On-line pervaporation, 18 518 On-line probes, for fermentation, 11 39 On-line vapor permeation, 18 518 On/off feedback controllers, 20 691 Onstream analyzers, 20 682 On-tank leak detection systems, 24 311 Onyx thermal printing process, 19 321 Oocytes, retroviral infection of, 12 457 Oolitic limestone, 15 28 Opacification, colorants for ceramics, 7 344-345... 

Oolite limestone, which-derives its name from its being composed of small round grains like the roe of a fish, is another excellent and pure carbonate of lime. 

Under the microscope the ore has an appearance suggestive of oolitic limestone, from which it has very probably been formed by molecular replacement of the calcium carbonate by ferrous carbonate, through the infiltration of waters containing the latter m solution.2... 

Figure 42 Number of occurrences of Phanerozoic ironstones (upper diagram, source Van Houten and Bhattacharyya, 1982) and oolitic limestones (lower diagram, source Wilkinson et al., 1985) as a function of geologic age. The relative sea-level curve is that of Hallam (1984). Minima in occurrences appear to correlate with times of sea level withdrawal from the continents (after Morse and Mackenzie, 1990).

A simplified stratigraphic section through the study area is presented in Fig. lb. In the study area, Precambrian rocks are overlain by a thick succession of Cambrian sandstones. The sandstones are in turn overlain by the Ordovician Prairie du Chien Group, the St. Peter Sandstone, and the Sinnipee Group (Fig. lb). The Prairie du Chien Group consists of dolomitized oolitic limestones, muddy facies, and stromatohtes, with cyclic interbedded thin sandstones and shales. A majorunconformity (Tippecanoe... 

Biscayne (Florida) 13,000 8600 Oolitic limestone Calcium bicarbonate... 

Inorganic precipitation of calcium carbonate occurs from both sea and inland waters (as used by geologists, precipitation refers to the relatively slow process of crystal growth on surfaces). This route has resulted in some commercially significant deposits, the most common of which are oolitic limestone and travertine (see section 2.2.1). Some minor dolomite sediments have been formed by direct precipitation from sea and lake waters. 

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. 

Pisolitic limestone is similar to oolitic limestone, but with a larger grain size (about 5 mm). 

Pisolite 1) A coarsely grained oolitic limestone deposit. 2) A small round or ellipsoidal accretionary body in a sedimentary deposit. A grain in a pisolitic deposit the term is... 

Chemical sedimentary rocks are formed as precipitates from supersaturated solutions precipitating out around. Oolitic limestone is an example of rock in this category. 

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. 

A fairly common variety of limestones in this category are the oolitic limestones, which are composed of so-called ooliths, i. e., more or less spherical rock particles grown by accretion around a nucleus and of the order of 1 mm in diameter. These calcareous ooliths are formed in shallow water (less than about 2 m depth) subject to considerable motion. When a certain amount of lime has been deposited around the nucleus (which may be a grain of sand or a shell fragment), the oolith sinks to the bottom by gravity. Portland limestone belongs to this type. 

There is a clear preference for very long-lived or even permanent sequestration. Such permanent sequestration is offered by an examination of geological processes, since it is clear that over archaeological time scales, a considerable amount of CO2 has been sequestered—for example, as oolitic limestone deposits and dolomite deposits. Nature has sequestered carbon in two ways ... 

As calcium carbonate generated by marine animals of various kinds, principally as shells or exoskeletons that are deposited on seabeds—this appears to be the method of formation of the very extensive oolitic limestone beds and... 

Figure 1. Scanning electron micrographs of Portland Oolitic limestone samples...

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