Some ooids form in fresh-water lakes, caves, caliche soils, hot springs, and rivers.
Oolitic limestones form prolific oil reservoirs. The width of the view is 5.
Some ooids are made of silica chert , dolomite or fine-grained phosphatic material collophane. Such ooids are typically formed in water rich in calcium carbonate for obvious reasons and for preference warm shallow water agitated by waves.
Jurassic Arab sequence in the Middle East, Smackover reservoir of the Gulf of Mexico, and several formations in the Anadarko and Appalachian basins among others are examples of oil reservoirs in oolitic limestones 4. Warm water is needed to lower the carbon dioxide content in water higher temperature reduces the ability of water to keep gases dissolved and thereby enhance the precipitation of calcium carbonate.
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Width of view 3 cm. Such ooids are formed by replacement of original calcium carbonate, but they may be also primary. Sturesson, U.
Concentric layering in iron-bearing ooids is thought to result from constant agitation of ooids associated with currents and expulsion of gas from the sediment 2. Oolite Oolite is a sedimentary rock made up of ooids ooliths that are cemented together. From Wikibooks, open books for an open world. Plainly, then, what we are looking at is ooids cemented together to form oolite.
This page was last edited on 26 October 2017, at 00: Sedimentary Geology 4.
Policies and guidelines Contact us. Rock formed from Calcium carbonate ooids is, by definition, a form of limestone , and is known as oolitic limestone or oolite. Larger grains with similar genesis are pisoids pisoliths. Mahengetang, Indonesia Geology 3. Most ooids are marine, forming in shallow less than 10 m, preferably even less than 2 meters , warm, and wave-agitated water such as the Persian Gulf and the Bahama Platform.
Views Read Edit View history. This is also the reason why ooids are so well-polished. It is believed that ooid formation is generally abiogenic process.