In sedimentology and geology, a nodule is a small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition, such as a pyrite nodule in coal, a chert nodule in limestone, or a phosphorite nodule in marineshale, from the enclosing sediment or sedimentary rock. Normally, a nodule has a warty or knobby surface and exists as a discrete mass within the host strata. In general, they lack any internal structure except for the preserved remnants of original bedding or fossils. Nodules are closely related to concretions and sometimes these terms are used interchangeably. Minerals that typically form nodules include calcite, chert, apatite (phosphorite), anhydrite, and pyrite.[1][2]
Nodular is used to describe a sediment or sedimentary rock composed of scattered to loosely packed nodules in matrix of like or unlike character. It is also used to describe mineral aggregates that occur in the form of nodules, e.g. colloform mineral aggregate with a bulbed surface.[1]
Nodule is also used for widely scattered concretionary lumps of manganese, cobalt, iron, and nickel found on the floors of the world's oceans. This is especially true of manganese nodules. Manganese and phosphorite nodules form on the seafloor and are syndepositional in origin. Thus, technically speaking, they are concretions instead of nodules.[1][2]
Chert and flint nodules are often found in beds of limestone and chalk. They form from the redeposition of amorphoussilica arising from the dissolution of siliceousspicules of sponges, or debris from radiolaria and the postdepositional replacement of either the enclosing limestone or chalk by this silica.[2]
See also
Chert – Hard, fine-grained sedimentary rock composed of cryptocrystalline silica
Flint – Cryptocrystalline form of the mineral quartz
References
^ abcNeuendorf, KKE, JP Mehl, Jr., and JA Jackson, eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ISBN0-922152-76-4
^ abcBoggs S, Jr. (2009) Petrology of Sedimentary Rocks. Cambridge University Press, Cambridge, United Kingdom. 600 pp. ISBN978-0-521-89716-7
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nodule, geology, metallic, concretions, seafloor, manganese, nodule, sedimentology, geology, nodule, small, irregularly, rounded, knot, mass, lump, mineral, mineral, aggregate, that, typically, contrasting, composition, such, pyrite, nodule, coal, chert, nodul. For metallic concretions on the seafloor see Manganese nodule In sedimentology and geology a nodule is a small irregularly rounded knot mass or lump of a mineral or mineral aggregate that typically has a contrasting composition such as a pyrite nodule in coal a chert nodule in limestone or a phosphorite nodule in marine shale from the enclosing sediment or sedimentary rock Normally a nodule has a warty or knobby surface and exists as a discrete mass within the host strata In general they lack any internal structure except for the preserved remnants of original bedding or fossils Nodules are closely related to concretions and sometimes these terms are used interchangeably Minerals that typically form nodules include calcite chert apatite phosphorite anhydrite and pyrite 1 2 Devonian nodular limestone Concretionary nodular limestone at Jinshitan Coastal National Geopark Dalian China Nodular is used to describe a sediment or sedimentary rock composed of scattered to loosely packed nodules in matrix of like or unlike character It is also used to describe mineral aggregates that occur in the form of nodules e g colloform mineral aggregate with a bulbed surface 1 Nodule is also used for widely scattered concretionary lumps of manganese cobalt iron and nickel found on the floors of the world s oceans This is especially true of manganese nodules Manganese and phosphorite nodules form on the seafloor and are syndepositional in origin Thus technically speaking they are concretions instead of nodules 1 2 Chert and flint nodules are often found in beds of limestone and chalk They form from the redeposition of amorphous silica arising from the dissolution of siliceous spicules of sponges or debris from radiolaria and the postdepositional replacement of either the enclosing limestone or chalk by this silica 2 See also EditChert Hard fine grained sedimentary rock composed of cryptocrystalline silica Flint Cryptocrystalline form of the mineral quartzReferences Edit a b c Neuendorf KKE JP Mehl Jr and JA Jackson eds 2005 Glossary of Geology 5th ed Alexandria Virginia American Geological Institute 779 pp ISBN 0 922152 76 4 a b c Boggs S Jr 2009 Petrology of Sedimentary Rocks Cambridge University Press Cambridge United Kingdom 600 pp ISBN 978 0 521 89716 7 This geology article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Nodule geology amp oldid 1093144023, wikipedia, wiki, book, books, library,
