Error propagation in equations for geochemical modeling of radiogenic isotopes in two-component mixing

This paper presents error propagation equations for modeling of radiogenic isotopes during mixing of two components or end-members. These equations ca n be used to estimate errors on an isotopic ratio in the mixture of two com ponents, as a function of the analytical errors or the total errors of geol ogical field sampling and analytical errors. Two typical cases ("Small erro rs" and "Large errors") are illustrated for mixing of Sr isotopes. Similar examples can be formulated for the other radiogenic isotopic ratios. Actual isotopic data for sediment and basalt samples from the Cocos plate are als o included to further illustrate the use of these equations. The isotopic c ompositions of the predicted mixtures can be used to constrain the origin o f magmas in the central part of the Mexican Volcanic Belt. These examples s how the need of high quality experimental data for them to be useful in geo chemical modeling of magmatic processes.