concordia diagram

== English == === Noun === concordia diagram (plural concordia diagrams) (geology, geochronology) 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. ==== Usage notes ==== The most commonly used concordia diagrams are the Tera–Wasserburg diagram and the Wetherill diagram. 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 ( U 238 → Pb 206 {\displaystyle {\ce {^{238}U\to ^{206}Pb}}} ) and the actinium series ( U 235 → Pb 207 {\displaystyle {\ce {^{235}U\to ^{207}Pb}}} ). 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 discordant: a set of such points may be called a discordia. 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 closure temperature. Discordant data points may appear on a discordia line, from which information can sometimes be gleaned. Points where the two decay processes agree about radiometric age are said to be concordant, and the set of such points is called the concordia. The concordia appears on the diagram as a concordia curve. ==== Hyponyms ==== Tera–Wasserburg diagram, Tera–Wasserburg concordia diagram Wetherill diagram, Wetherill concordia diagram ==== Translations ==== === See also === errorchron isochron isochron diagram === Further reading === Radiometric dating on Wikipedia.Wikipedia Uranium–lead dating on Wikipedia.Wikipedia Uranium–thorium dating on Wikipedia.Wikipedia Lead–lead dating on Wikipedia.Wikipedia Decay chain § Uranium series on Wikipedia.Wikipedia Decay chain § Actinium series on Wikipedia.Wikipedia Isochron dating on Wikipedia.Wikipedia