εNd and CHUR
The deviation, in parts per 10,000, of a sample 143Nd/144Nd ratio from that of the chondritic uniform reservoir (CHUR), which stands for the bulk Earth, computed at the age of the rock. Negative values point to an old crustal source, positive values to a depleted mantle.
Composition
εNd(t) = [(143Nd/144Nd)sample(t) / (143Nd/144Nd)CHUR(t) - 1] × 10,000; present-day CHUR: 143Nd/144Nd = 0.512638 and 147Sm/144Nd = 0.1967.
Sources
In the atlas
- Neves-Corvo Portugal
- Shangfang China
- Bailashui (Furong ore field) China