Calcilutite (also known as cementstone)
is a type of
limestone that is composed of predominantly, more than 50 percent, of either clay-size or both silt-size and clay-size detrital (transported)
carbonate grains. These grains consist either of
fossil fragments,
ooids,
intraclasts,
pellets, other grains, or some combination of them. The term calcilutite was originally proposed in 1903 by Grabau
[Grabau, A.W. (1903) ''Paleozoic coral reefs.'' Geological Society of America Bulletin. vol. 14, pp. 337-352.][Grabau, A.W. (1904) ''On the classification of sedimentary rocks.'' American Geologist. vol. 33, pp. 228-247.] as a part of his calcilutite,
calcarenite and
calcirudite classification system based upon the size of the detrital grains composing a limestone.
[Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ][Flügel, E. (2010) ''Microfacies of Carbonate Rocks'', 2nd ed. Springer-Verlag Berlin, Germany. 976 pp. ] In the original classification
of limestone according to the dominant grain-size,
calcisiltites were not named and are classified as calcilutite. In this classification, which the majority of geologists follow, a calcilutite consists of both silt- and clay-size, less than 0.062 mm in diameter, grains. It is the carbonate equivalent of a
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
(not to be confused with a 'mudstone' of the Dunham Limestone classification).
[Folk, R.L., 1962, ''Spectral subdivision of limestone types. ''. In Ham, W. E.. Classification of carbonate rocks. American Association of Petroleum Geologists Memoir. no. 1, pp. 62-84.] Calcilutites can accumulate in a wide variety of marine and
lacustrine environments.
[Scholle, P.A., D.G. Bebout, and C.H. Moore (1983) ''Carbonate Depositional Environments. '' Memoir no. 33. Tulsa, Oklahoma, American Association of Petroleum Geologists. 708 pp. ]
References
Limestone
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