Model Ages (Sm-Nd)
A neodymium model age is an estimate of the age of “crustal formation” based on the assumption of a model composition for the mantle source. It is most commonly used to date the ages of crustal terranes within Precambrian orogenic belts or to estimate the provenance age of clastic sedimentary rocks.
Nd model age dating is probably the most misunderstood of the major geological dating methods. As the name indicates, Nd model ages are dependant on a mantle model to determine ages, and their accuracy is therefore dependant on the suitability of the mantle model. Nd model ages also have relatively large analytical uncertainties of around +/− 20 Myr. However, they are uniquely powerful in determining crustal formation ages, representing the time when crustal blocks were first created by mantle-derived magmatism, most commonly above subduction zones. In contrast, the U-Pb dating method provides much more precise and accurate ages for igneous crystallization, but can...
KeywordsCrustal Formation Mantle Model Grenville Orogeny Igneous Crystallization Large Analytical Uncertainty
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