Calcisiltite is a type of
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 ...
that is composed predominantly, more than 50 percent, of detrital (transported)
silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...
-size
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
grains. These grains consist either of the silt-size particles of
ooid
Ooids are small (commonly ≤2 mm in diameter), spheroidal, "coated" (layered) sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals. Ooids usually form on the sea floor, mo ...
s, fragments of fossil shells, fragments of older
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 ...
s and
dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
s,
intraclasts
Intraclasts are irregularly shaped grains that form by syndepositional erosion of partially lithified sediment.
Gravel grade material is generally composed of whole disarticulated or broken skeletal fragments together with sand grade material of wh ...
,
pellets, other carbonate grains, or some combination of these. Calcisiltite is the carbonate equivalent of a
siltstone.
[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. ] Calcisiltites can accumulate in a wide variety of coastal,
lacustrine
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
, and marine environments. It is typically the product of abrasion and
bioerosion.
[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. ]
The term calcisiltite was not an original part of the
calcilutite
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 foss ...
,
calcarenite
Calcarenite is a type of limestone that is composed predominantly, more than 50 percent, of detrital (transported) sand-size (0.0625 to 2 mm in diameter), carbonate grains. The grains consist of sand-size grains of either corals, shells, ooi ...
and
calcirudite Calcirudite is a type of limestone that is composed predominantly, more than 50 percent, of carbonate grains that are larger in size than sand (2 mm in diameter). The grains can consist of either fragments of fossils, fragments of older limesto ...
classification system for limestones, which 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.] proposed in 1903. Instead, the term calcisiltite was created by Kay
[Kay, G.M. (1951) ''North American geosynclines.'' Memoir no. 48. Boulder, Colorado, Geological Society of America. 143 pp.] in 1951 for limestone consisting predominantly of detrital silt-size, 0.062 to 0.002 mm, grains. As a result, calcisiltite is equivalent to the coarser part of "calcilutite" as it was originally proposed by Grabau and as calcilutite is normally defined and used by geologists. Calcisiltite is the carbonate equivalent of
siltstone.
[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.]
References
Limestone
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