The composition of the depleted reservoir relative to the CHUR evolution line, at time T, is given by the equation. ɛNd(T) = 0.25 T2 – 3 T + 8.5. Sm-Nd model ages calculated using this curve are denoted as TDM ages.

## What is model age?

Definition. 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.

## What is Chur geology?

- Chondritic uniform reservoir (CHUR) is a scientific model in astrophysics and geochemistry for the mean chemical composition of the part of the Solar Nebula from which, during the formation of the Solar System, chondrites formed.

## Can I be a model at age 30?

Modeling from 30 with previous experience If you have already gained experience as a model at photo shoots, commercials or fashion shows, it is of course much easier for you to join the model agency. Many agencies, including ourselves, are looking for good models from the age of 30.

## Is ND 142 stable?

Naturally occurring neodymium (60Nd) is composed of 5 stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant (27.2% natural abundance), and 2 long-lived radioisotopes, 144Nd and 150Nd.