Nonchondritic ¹⁴²Nd in suboceanic mantle peridotites

The discovery that several solid Earth reservoirs have a superchondritic 142 Nd/ 144 Nd ratio led to the hypothesis that either the bulk silicate Earth is not chondritic or that a subchondritic reservoir lies hidden somewhere within the Earth's interior. One important reservoir, i.e., mid‐ocean ridge peridotites representing the main component of the upper oceanic mantle and the source of mid‐ocean ridge basalt, has never been tested for 142 Nd/ 144 Nd. We determined the 142 Nd/ 144 Nd ratio in clinopyroxene separated from two peridotites and a pyroxenite from the SW Indian Ridge and one peridotite from the northern Mid‐Atlantic Ridge. All samples analyzed have superchondritic 142 Nd/ 144 Nd ratios in line with mantle‐derived material measured to date, except for some ancient cratonic rocks.