Concordia diagram

English

A concordia diagram (Wetherill diagram)

Noun

1. Template:Lb Any of several types of diagram, used in connection with uranium–lead dating, in which each axis encodes differently sourced information about the radiometric age of the mineral being dated.
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Usage notes

• The most commonly used concordia diagrams are the Template:M and the Template:M. Both are used in conjunction with uranium–lead dating ("U–Pb dating"), which involves measuring isotopes from the start and end points of two decay chains: the uranium series (${\phantom{A}}_{\phantom{}}^{\phantom{238}}{\phantom{A}}_{\phantom{2}}^{\phantom{2}238}\mathrm{U}\to {\phantom{A}}_{\phantom{}}^{\phantom{206}}{\phantom{A}}_{\phantom{2}}^{\phantom{2}206}\mathrm{P}\mathrm{b}$) and the actinium series (${\phantom{A}}_{\phantom{}}^{\phantom{235}}{\phantom{A}}_{\phantom{2}}^{\phantom{2}235}\mathrm{U}\to {\phantom{A}}_{\phantom{}}^{\phantom{207}}{\phantom{A}}_{\phantom{2}}^{\phantom{2}207}\mathrm{P}\mathrm{b}$).
• Each plottable point on a diagram represents two notional radiometric ages (one for each decay chain) of a rock sample.
• Points where the data from the decay chains yield different ages are said to be Template:M: a set of such points may be called a Template:M. Discordance is commonly the result of "lead loss" ("Pb loss") and/or "uranium loss" ("U loss"). Such loss may present itself if, sometime since it was formed, the crystal's temperature has risen above its Template:M. Discordant data points may appear on a Template:M, from which information can sometimes be gleaned.
• Points where the two decay processes agree about radiometric age are said to be Template:M, and the set of such points is called the Template:M. The concordia appears on the diagram as a Template:M.

Hyponyms

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Translations

• French: Template:T-needed
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• Italian: Template:T-needed

See also

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Further reading

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