Mudstone

Mudstone formation on Lyme Regis East Beach.

Mudstone (also called mudrock) is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm (0.0025 in) with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called shale, as distinct from mudstone. The lack of fissility or layering in mudstone may be due either to original texture or to the disruption of layering by burrowing organisms in the sediment prior to lithification. Mud rocks, such as mudstone and shale comprise some 65% of all sedimentary rocks. Mudstone looks like hardened clay and, depending upon circumstances under which it was formed, it may show cracks or fissures, like a sun-baked clay deposit.^[1]

They can be separated into these categories:

• Siltstone - greater than half of the composition is silt-sized particles.
• Claystone - greater than half of the composition is clay-sized particles.
• Mudstone - hardened mud; a mix of silt and clay sized particles. Mudstone can include:
  • Shale - exhibits lamination or fissility.
  • Argillite - has undergone low grade metamorphism.^[1]

Dunham classification of limestones

In the Dunham classification of limestones, a mudstone is a matrix-supported carbonate rock that contains less than 10% allochems in a carbonate mud matrix. As defined by the Dunham classification, a mudstone is more or less synonymous with calcilutite.^[2]

References

1. ^ ^{a b} Blatt, H., and R.J. Tracy, 1996, Petrology. New York, New York, W. H. Freeman, 2nd ed, 529 pp. ISBN 0-7167-2438-3
2. ^ Dunham, R.J. (1962). Classification of carbonate rocks according to depositional texture. In Ham, W. E.. Classification of carbonate rocks. American Association of Petroleum Geologists Memoir. no. 1, pp. 108-121.

This article related to petrology is a stub. You can help Wikipedia by expanding it.v · Categories: Sedimentary rocks Petrology stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать реферат Fitzedward Hall Stone ship Look at other dictionaries: Mudstone — photographiée dans les environs de Lyme Regis. La mudstone est une fine roche sédimentaire composée à l origine d argile ou de boue. La granulométrie est si petite qu elle ne peut être distinguée sans microscope. Le terme est d origine… …   Wikipédia en Français mudstone — [mud′stōn΄] n. a fine grained sedimentary rock that is formed from silt and clay, similar to shale but not distinctly laminated …   English World dictionary mudstone — /mud stohn /, n. Geol. a clayey rock with the texture and composition of shale but little or no lamination. [1730 40; MUD + STONE] * * * ▪ rock       sedimentary rock composed primarily of clay or silt sized particles (less than 0.063 mm [0.0025… …   Universalium mudstone — noun Date: circa 1736 an indurated shale produced by the consolidation of mud …   New Collegiate Dictionary mudstone — noun A fine grained sedimentary rock whose original constituents were clays or muds …   Wiktionary mudstone —     a) A blocky or massive, fine grained sedimentary rock in which the proportions of clay and silt are approximately equal.     b) A general term that includes clay, silt, claystone, siltstone, shale, and argillite, and that should be used only… …   Glossary of landform and geologic terms mudstone — n. type of shale (Geology) …   English contemporary dictionary mudstone — noun a dark sedimentary rock formed from consolidated mud and lacking the laminations of shale …   English new terms dictionary mudstone — mud•stone [[t]ˈmʌdˌstoʊn[/t]] n. gel a clayey rock with the texture and composition of shale but little or no lamination • Etymology: 1730–40 …   From formal English to slang mudstone — /ˈmʌdstoʊn/ (say mudstohn) noun a clayey rock of nearly uniform texture throughout, with little or no lamination …   18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”