Micrite is a

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

constituent formed of

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an ad ...

particles ranging in diameter up to four μm formed by the recrystallization of lime mud. Flügel, Erik, ''Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,'' Springer, pp 74-94, 2004 The term was coined in 1959 by

Robert Folk Robert Folk (born March 5, 1949) is an American film and television composer and conductor who has written many movie scores, as well as other orchestral music in a classical style. Life and career Robert Folk is a graduate and former facult ...

for his carbonate rock classification system. Micrite is derived from MICRocrystalline calcITE. In the

Folk classification The Folk classification, in geology, is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas. Folk's sandstone (clastic) c ...

micrite is a

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolosto ...

dominated by fine-grained calcite. Carbonate rocks that contain fine-grained calcite in addition to

allochem Allochem is a term introduced by FolkFolk, R. L. (1959) ''Practical petrographic classification of limestones.'' American Association of Petroleum Geologists Bulletin. 43, pp. 1–38. to describe the recognisable "grains" in carbonate rocks. Any fr ...

s are named ''intramicrite'', ''oomicrite'', ''biomicrite'' or ''pelmicrite'' under the Folk classification depending on the dominant allochem. Micrite is lime mud, carbonate of mud grade. Micrite as a component of carbonate rocks can occur as a matrix, as micrite envelopes around allochems or as

peloids Peloids are allochems that are composed of micrite, irrespective of size, shape, or origin. The two primary types of peloids are pellets and intraclasts Intraclasts are irregularly shaped grains that form by syndepositional erosion of partially ...

. The origin of micrites is still a problem in carbonate sedimentology due to the non-uniqueness of the processes generating it. Micrite can be generated through multiple processes. In lakes and some marine environments, lime mud that could become micrite can form chemically or biochemically through whiting events, whereas in warm stratified marine waters it might be forming chemically. Alternatively, microbial process known as micritization may lead to micrite formation. Other processes which might produce micrite include the disaggregation of peloids, bioerosion, the mechanical degradation of larger carbonate grains and dissolution-reprecipitation processes.

References

*Folk, R.L., 1959, Practical petrographic classification of limestones: American Association of Petroleum Geologists Bulletin, v. 43, p. 1-38. *https://www2.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?Term=micrite Limestone {{petrology-stub