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mineral versus other REE in that mineral (a positive anomaly). The rest of the magma will then be relatively depleted in Eu with a concentration of Eu lower than expected versus the concentrations of other REEs in that magma. If the Eu-depleted magma is then separated from its plagioclase crystals and subsequently solidifies, its chemical composition will display a negative Eu anomaly (because the Eu is locked up in the plagioclase left in the magma chamber). Conversely, if a magma
20:
114:, shows a large negative Eu anomaly. This has led geologists to speculate as to the genetic relationship between the lunar highlands and mare. It is possible that much of the Moon's Eu was incorporated into the earlier, plagioclase-rich highlands, leaving the later basaltic mare strongly depleted in Eu.
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Enrichment or depletion is generally attributed to europium's tendency to be incorporated into plagioclase preferentially over other minerals. If a magma crystallizes stable plagioclase, most of the Eu will be incorporated into this mineral, causing a higher than expected concentration of Eu in the
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ions, leading to chemical reaction differences in how these ions can partition versus the 3+ REEs. In the case of Eu, its reduced divalent (2+) cations are similar in size and carry the same charge as Ca, an ion found in
275:
Bau, M. (1991). "Rare-earth element mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium".
323:
216:
232:
Weill, D. F.; Drake, M. J. (1973). "Europium
Anomaly in Plagioclase Feldspar: Experimental Results and Semiquantitative Model".
83:, it is preferentially incorporated into plagioclase in its divalent form (Eu) in a reducing magma, where it substitutes for
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a europium anomaly is said to be "positive" if the Eu concentration in the mineral is enriched relative to the other
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plagioclase crystals before solidification, its rock composition will display a relatively positive Eu anomaly.
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A well-known example of the Eu anomaly is seen on the Moon. REE analyses of the Moon's light-colored
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35:(Eu) concentration in a mineral is either enriched or depleted relative to some standard, commonly a
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Sinha, Shyama P.; Scientific
Affairs Division, North Atlantic Treaty Organization (1983).
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51:(REEs), and is said to be "negative" if Eu is depleted relative to the other REEs.
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Rare-earth element abundances of basalts, of both terrestrial and lunar origins
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Relative europium concentration in a mineral is either enriched or depleted
164:"Sources of Extraterrestrial Rare Earth Elements: To the Moon and Beyond"
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show a large positive Eu anomaly due to the plagioclase-rich
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McLeod, Claire L.; Krekeler, Mark. P. S. (August 2017).
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Mcsween, Jr., Harry Y.; Huss, Gary R. (30 June 2010).
58:form relatively large trivalent (3+) ions, Eu and
209:Systematics and the properties of the lanthanides
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79:in its trivalent form (Eu) in an oxidizing
312:"Composition of the Lunar Mantle and Core"
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66:, europium forms 2+ ions, and Ce forms
106:comprising the highlands. The darker
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75:and other minerals. While Eu is an
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31:is the phenomenon whereby the
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254:10.1126/science.180.4090.1059
297:10.1016/0009-2541(91)90115-8
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189:10.3390/resources6030040
110:, consisting mainly of
205:"The Europium anomaly"
41:mid-ocean ridge basalt
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62:(Ce) have additional
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318:. pp. 456–460.
211:. pp. 550–553.
77:incompatible element
289:1991ChGeo..93..219B
246:1973Sci...180.1059W
240:(4090): 1059–1060.
180:2017Resou...6...40M
144:Rare-earth elements
49:rare-earth elements
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325:978-0-521-87862-3
218:978-90-277-1613-2
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283:(3–4): 219–230.
277:Chemical Geology
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174:(3). MDPI: 40.
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45:geochemistry
43:(MORB). In
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345:Lanthanides
139:Lanthanides
104:anorthosite
93:accumulates
73:plagioclase
56:lanthanides
339:Categories
150:References
108:lunar mare
54:While all
168:Resources
37:chondrite
262:17806582
134:Europium
118:See also
64:valences
33:europium
285:Bibcode
242:Bibcode
234:Science
176:Bibcode
85:calcium
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124:Cerium
112:basalt
87:(Ca).
60:cerium
81:magma
320:ISBN
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