Concordia

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Full definition of concordia

(countable and uncountable; plural concordias)

(geology, geochronology) A set of plotted points, appearing as a curve on a concordia diagram or isochron diagram, representing sample data from rock of the same age; the condition of being a member of said set (or on said curve).

1979, Contributions to Geology, Volumes 17-19; Volume 3, University of Wyoming, page 174,Points above concordia indicate uranium loss and those below indicate uranium gain.
1994 Elsevier, H.-G. Attendorn, R. Bowen, Isotopes in the Earth Sciences, Chapman & Hall, page 131,Such lower intersections of resultant discordias with U-Th-Pb concordias are not significant in terms of geological time, merely changes which took place in the

Th/U ratios or lead isotope ratios through the factors alluded to above.

2005, Gunter Faure, Teresa M. Mensing, Isotopes: Principles and Applications, 3rd Edition, Wiley, page 521,The addition of U to a carbonate sample on concordia causes the point to move off concordia in the direction of the origin....The patterns that develop in the

^{231}Pa-^{230}Th concordia diagrams are similar to the responses of Pa-Th concordias presented in Section 10.5a.