Atomic-scale Th and U segregation into dislocation cores and U-Pb age discordance in xenotime
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F23%3A00570948" target="_blank" >RIV/67985831:_____/23:00570948 - isvavai.cz</a>
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S0024493723000890?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0024493723000890?via%3Dihub</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.lithos.2023.107105" target="_blank" >10.1016/j.lithos.2023.107105</a>
Alternative languages
Result language
angličtina
Original language name
Atomic-scale Th and U segregation into dislocation cores and U-Pb age discordance in xenotime
Original language description
The distribution of Th and U in a crystal of pegmatitic xenotime-(Y) (henceforth named xenotime) from Ås II feldspar quarry (Evje, S Norway) has been studied with transmission electron microscopy (TEM) to determine submicron- to nanoscale processes that might have affected U-(Th-)Pb age record. Xenotime contains high Th and U unaltered domains, and Th and U depleted altered domains, which contain numerous inclusions of (Th, U)- silicate and uraninite. A focused ion beam foil (FIB-foil) prepared from the unaltered xenotime, examined with transmission electron microscopy (TEM), revealed a network of ca. 15–20 nm-thick and up to several hundred nanometers-long dislocations. The dislocation cores contain U, Th and Si enriched material, and are surrounded on both sides by radiation-damaged xenotime. Rarely present “empty” dislocations are indicative of nanoscale-sized porosity in xenotime. The presence of a network of line defects in xenotime indicates plastic deformation of the xenotime crystal, which resulted in an initial stage of the formation of partially open phase boundaries. The dislocations network has been infiltrated by fluid, which mediated coupled dissolutionreprecipitation reactions. Segregation of U and Th into the dislocation cores, and selective transport of highly fluid-mobile U outside of the xenotime is suggested to be a source of Pb-excess and reverse discordance in the 207Pb/235U vs. 206Pb/238U concordia diagrams. The new finding of migration and finally segregation of U and Th into dislocation cores at the atomic-scale demonstrates the importance of nanoscale investigations for better understanding of the obtained age data and provides crucial implications for applications of xenotime geochronology.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10504 - Mineralogy
Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Lithos
ISSN
0024-4937
e-ISSN
1872-6143
Volume of the periodical
444-445
Issue of the periodical within the volume
May
Country of publishing house
NL - THE KINGDOM OF THE NETHERLANDS
Number of pages
5
Pages from-to
107105
UT code for WoS article
000951987800001
EID of the result in the Scopus database
2-s2.0-85149741980