Batuan enapan: Perbezaan antara semakan
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Laman baru: frame|right|Dua jenis batu enapan: limey shale dilapis dengan batu kapur. Dataran Cumberland, [[Tennessee.]] '''Batu enapan''' merupakan salah satu dari ... |
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'''Batu enapan''' merupakan salah satu dari tiga jenis bentuk kumpulan batu (yang lain adalah batu igneous dan metamorphic). Batu yang terbentuk dari enapan melitupi 75% daripada tahan daratan [[Bumi]], dan termasuk jenis biasa seperti kapur, batu kapur, [[dolomite]], [[batu pasir]], dan [[shale]].
Batu enapan dikelaskan menurut sumber enapan mereka, dan biasanya adalah:
* batu klastik terbentuk dari serpihan yang pecah dari batu asal, melalui
**
** [[hakisan]] oleh [[air]], air batu atau angin, diikuti oleh hanyutan mendapan, sering kali melalui apungan, ketempat ia mendak;
* aktiviti biogenik; atau
* mendakan dari sebatian.
Mendakan ini kemudiannya mengeras dan bertukar menjadi batu melalui proses lithifikasi.
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Sedimentary [[rock (geology)|rock]]s are formed because of the [[overburden pressure]] as particles of [[sediment]] are [[settling|deposited]] out of air, ice, wind, or water flows carrying the particles in [[suspension (chemistry)|suspension]]. As sediment deposition builds up, the overburden (or 'lithostatic') pressure squeezes the sediment into layered solids in a process known as [[lithification]] ('rock formation') and the original [[connate fluids]] are expelled. The term [[diagenesis]] is used to describe all the chemical, physical, and biological changes, including [[cementation]], undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface weathering.
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The sedimentary rock cover of the continents of the Earth's [[Crust (geology)|crust]] is extensive, but the total contribution of sedimentary rocks is estimated to be only five percent of the total. As such, the sedimentary sequences we see represent only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks.
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Batu enapan dikelaskan kepada tiga kumpulan. Kumpulan ini adalah klastik, mendakan kimia dan biokimia atau biogenik.
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===Clastic===
Clastic sedimentary rocks are composed of discrete fragments or clasts of materials derived from other rocks. They are composed largely of [[quartz]] with other common minerals including [[feldspar]], [[amphibole]]s, [[clay minerals]], and sometimes more exotic [[igneous]] and [[metamorphic rock|metamorphic]] minerals.
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The shape of the particles in sedimentary rocks has an important effect on the ability of micro-organisms to colonize them. This interaction is studied in the science of [[geomicrobiology]]. One measure of the shape of these particles is the roundness factor, also known as the Krumbein number after the geologist [[William C. Krumbein|W. C. Krumbein]].
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==Rujukan==
*Blatt, Harvey and Robert J. Tracy, 1996, ''Petrology: Igneous, Sedimentary and Metamorphic'', Freeman, 2nd Ed. ISBN 0-7167-2438-3
*Folk, R.L., 1965, [http://www.lib.utexas.edu/geo/folkready/folkprefrev.html ''Petrology of sedimentary rocks'' PDF version]. Austin: Hemphill’s Bookstore. 2nd ed. 1981, ISBN 0-914696-14-9
*[http://csmres.jmu.edu/geollab/fichter/SedRx/sedclass.html Basic Sedimentary Rock Classification]
{{Link FA|sk}}
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