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==Mineralised== {{further|Shelled protists}} ===Siliceous=== [[Siliceous ooze]] is a type of biogenic [[pelagic sediment]] located on the [[Abyssal|deep]] [[ocean floor]]. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor.<ref>{{Citation|last1=Mulder|first1=Thierry|title=Progress in Deep-Sea Sedimentology|date=2011|work=Deep-Sea Sediments|pages=1–24|publisher=Elsevier|isbn=9780444530004 | doi = 10.1016/b978-0-444-53000-4.00001-9 |last2=Hüneke|first2=Heiko|last3=Van Loon|first3=A.J.}}</ref> Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms.<ref>{{Cite journal|last1=Bohrmann|first1=Gerhard|last2=Abelmann|first2=Andrea|last3=Gersonde|first3=Rainer|last4=Hubberten|first4=Hans|last5=Kuhn|first5=Gerhard|date=1994|title=Pure siliceous ooze, a diagenetic environment for early chert formation |journal=Geology|volume=22|issue=3|pages=207|doi=10.1130/0091-7613(1994)022<0207:psoade>2.3.co;2|bibcode=1994Geo....22..207B}}</ref> Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as [[diatom]]s and [[radiolarian]]s. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica [[SiO2|Si(O<sub>2</sub>)]], as opposed to [[calcareous ooze]]s, which are made from skeletons of calcium carbonate organisms (i.e. [[coccolithophore]]s). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the [[silica cycle]].<ref>{{Cite journal|last=DeMaster|first=David J.|date= October 1981 |title=The supply and accumulation of silica in the marine environment |journal=Geochimica et Cosmochimica Acta|volume=45|issue=10|pages=1715–1732|doi=10.1016/0016-7037(81)90006-5 |bibcode=1981GeCoA..45.1715D}}</ref> Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes. {|class="wikitable" ! colspan=8 |{{center|[[Siliceous ooze]]}} |- ! mineral<br />forms ! protist<br />involved ! ! name of skeleton ! width=100px | typical size ! colspan=2 | |- | width=90px rowspan=2 align=center | [[Silicon oxide|SiO<sub>2</sub>]]<br />[[silica]]<br />[[quartz]]<br />[[glass]]<br />[[opal]]<br />[[chert]] | [[diatom]] | style="background:#000000;"| [[File:Lyrella hennedy 1600x contrast invertion.jpg|90px]] | [[frustule]] | 0.002 to 0.2 mm{{hsp}}<ref name="HasleSyvertsen1996">{{cite book|first1=Grethe R.|last1=Hasle|first2=Erik E. |last2=Syvertsen |first3=Karen A. |last3=Steidinger |first4=Karl|last4=Tangen|editor-first=Carmelo R.|editor-last=Tomas|title=Identifying Marine Diatoms and Dinoflagellates|chapter-url=https://books.google.com/books?id=KQxPtwonlqoC|access-date=2013-11-13|date=1996-01-25|publisher=Academic Press|isbn=978-0-08-053441-1|pages=5–385|chapter=Marine Diatoms}}</ref> | [[File:Stephanopyxis grunowii.jpg|100px]] | diatom microfossil from 40 million years ago |- | [[radiolarian]] | style="background:#000000;"| [[File:Calocycloma sp. - Radiolarian (32163186535).jpg|90px]] | [[Test (biology)|test]] or shell | 0.1 to 0.2 mm{{hsp}} | [[File:Radiolarian - Heliodiscus umbonatus (Ehr.), Haeckel (28187768550).jpg|100px]] | elaborate silica shell of a radiolarian |- |} <gallery mode=packed heights=160px style=float:left;> File:Diatomaceous Earth BrightField.jpg|[[Diatomaceous earth]] is a soft, [[siliceous]], [[sedimentary rock]] made up of microfossils in the form of the [[frustule]]s (shells) of centric and pennate [[diatom]]s (click to magnify) File:Detail, CSIRO ScienceImage 7632 SEM diatom (cropped).jpg|{{center|[[Centric diatom]]<br />(radial symmetry)}} File:Pennate diatoms (3075304186).jpg|{{center|[[Pennate diatom]]<br />(bilateral symmetry)}} </gallery> {{multiple image | align = right | direction = horizontal | width1 = 195 | image1 = The silicoflagellate Dictyocha fibula.png | alt1 = | caption1 = {{center|[[Silicoflagellate]]}} | width2 = 130 | image2 = Radiolarian - Podocyrtis ampla (29391267424).jpg | alt2 = | caption2 = {{center|[[Radiolarian]]}} }} [[File:Phytolith 3.png|thumb|upright=1.3| {{center|Phytolith from a leaf of the tree<br />''[[Cornus controversa]]''<ref name=Ge2020>{{cite journal |doi = 10.1038/s41598-020-72547-w|title = Phytoliths in selected broad-leaved trees in China|year = 2020|last1 = Ge|first1 = Yong|last2 = Lu|first2 = Houyuan|last3 = Wang|first3 = Can|last4 = Gao|first4 = Xing|journal = Scientific Reports|volume = 10|issue = 1|page = 15577|pmid = 32968165|pmc = 7512002|bibcode = 2020NatSR..1015577G}}</ref> • <small>scale bar 20 μm</small>}}]] {{clear left}} [[Phytoliths]] (Greek for ''plant stones'') are rigid, microscopic structures made of [[silica]], found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant. Phytoliths come in varying shapes and sizes. The term "phytolith" is sometimes used to refer to all mineral secretions by plants, but more commonly refers to siliceous plant remains.<ref name="Piperno, Dolores R. 2006">Piperno, Dolores R. (2006). Phytoliths: A Comprehensive Guide for Archaeologists and Paleoecologists. AltaMira Press {{ISBN|0759103852}}.</ref> {{clear}} ===Calcareous=== The term ''calcareous'' can be applied to a fossil, sediment, or sedimentary rock which is formed from, or contains a high proportion of, [[calcium carbonate]] in the form of [[calcite]] or [[aragonite]]. Calcareous sediments ([[limestone]]) are usually deposited in shallow water near land, since the carbonate is precipitated by marine organisms that need land-derived nutrients. Generally speaking, the farther from land sediments fall, the less calcareous they are. Some areas can have interbedded calcareous sediments due to storms, or changes in ocean currents. [[Calcareous ooze]] is a form of calcium carbonate derived from planktonic organisms that accumulates on the [[sea floor]]. This can only occur if the ocean is shallower than the [[carbonate compensation depth]]. Below this depth, calcium carbonate begins to dissolve in the ocean, and only non-calcareous sediments are stable, such as [[siliceous ooze]] or [[pelagic red clay]]. {|class="wikitable" ! colspan=8 |{{center|[[Calcareous]] ooze}} |- ! mineral<br />forms ! protist<br />involved ! ! name of skeleton ! width=100px | typical size ! colspan=2 | |- | width=90px rowspan=3 align=center | [[Calcium carbonate|CaCO<sub>3</sub>]]<br />[[calcite]]<br />[[aragonite]]<br />[[limestone]]<br />[[marble]]<br />[[chalk]] | [[foraminiferan]] | style="background:#000000;"| [[File:Foram-globigerina hg.jpg|90px]] | [[Foraminifera test|test]] or shell | many under 1 mm | [[File:Globigerina.png|100px]] | [[Calcified]] [[Foraminifera test|test]] of a planktic foraminiferan. There are about 10,000 living species of foraminiferans<ref name="adl2007">{{cite journal | last1 = Ald | first1 = S.M. | display-authors = etal | year = 2007 | title = Diversity, Nomenclature, and Taxonomy of Protists | journal = Syst. Biol. | volume = 56 | issue = 4 | pages = 684–689 | doi = 10.1080/10635150701494127 | pmid = 17661235 | doi-access = free }}</ref> |- | [[coccolithophore]] | style="background:#000000;"| [[File:Coccolithus pelagicus 2.jpg|90px]] | [[coccolith]]s | under 0.1 mm{{hsp}}<ref name=Moheimani2012>{{citation |journal=[[Algal Research]] |volume=1 |issue=2 |year=2012 |pages=120–133 |title=Bioremediation and other potential applications of coccolithophorid algae: A review. . Bioremediation and other potential applications of coccolithophorid algae: A review |first1=N.R. |last1=Moheimani |first2=J.P. |last2=Webb |first3= M.A. |last3=Borowitzka |doi=10.1016/j.algal.2012.06.002}}</ref> | [[File:CSIRO ScienceImage 7202 SEM Coccolithophorid.jpg|100px]] | Coccolithophores are the largest global source of biogenic calcium carbonate, and significantly contribute to the global [[carbon cycle]].<ref>{{cite journal | last1 = Taylor | first1 = A.R. | last2 = Chrachri | first2 = A. | last3 = Wheeler | first3 = G. | last4 = Goddard | first4 = H. | last5 = Brownlee | first5 = C. | year = 2011 | title = A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores | journal = PLOS Biology | volume = 9 | issue = 6| page = e1001085 | doi = 10.1371/journal.pbio.1001085 | pmid = 21713028 | pmc = 3119654 | doi-access = free }}</ref> They are the main constituent of chalk deposits such as the [[white cliffs of Dover]]. |- |} <gallery mode=packed heights=160px style=float:left;> File:Nanoplankton-fossil-sediment hg.jpg| {{center| Calcareous microfossils from marine sediment consisting mainly of star-shaped [[discoaster]] with a sprinkling of coccoliths}} File:PSM V44 D483 Globigerina ooze.jpg|Illustration of a ''[[Globigerina]]'' ooze File:FMIB 47660 Shells from Globigerina Ooze.jpeg|Shells ([[Test (biology)|tests]]), usually made of calcium carbonate, from a [[foraminifera]]l ooze on the deep ocean floor </gallery> [[File:Mesozoic benthic foraminifera.png|thumb| {{center|[[Mesozoic]] benthic foraminifera{{hsp}}<ref>{{cite journal |doi = 10.5194/jm-37-395-2018|title = New species of Mesozoic benthic foraminifera from the former British Petroleum micropalaeontology collection|year = 2018|last1 = Fox|first1 = Lyndsey R.|last2 = Stukins|first2 = Stephen|last3 = Hill|first3 = Tom|last4 = Bailey|first4 = Haydon W.|journal = Journal of Micropalaeontology|volume = 37|issue = 1|pages = 395–401|bibcode = 2018JMicP..37..395F|hdl = 10141/622407|hdl-access = free | doi-access=free }}</ref>}}]] [[File:Oscillatoriopsis longa fossil.jpg|thumb|upright=0.8|center| {{center|[[Cyanobacteria]]l remains of an annulated tubular microfossil ''Oscillatoriopsis longa''{{hsp}}<ref>{{cite journal |doi = 10.1111/pala.12374|title = First record of Cyanobacteria in Cambrian Orsten deposits of Sweden|year = 2018|last1 = Castellani|first1 = Christopher|last2 = Maas|first2 = Andreas|last3 = Eriksson|first3 = Mats E.|last4 = Haug|first4 = Joachim T.|last5 = Haug|first5 = Carolin|last6 = Waloszek|first6 = Dieter|journal = Palaeontology|volume = 61|issue = 6|pages = 855–880| bibcode=2018Palgy..61..855C |doi-access = free}}</ref><br /><small>Scale bar: 100 μm</small>}}]] {{clear}}
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