Isotopic ratios of clinopyroxenes of abyssal peridotites from the Doldrums Fracture Zone (°7N, Mid Atlantic Ridge)

This database contains Nd-Hf isotope compositions of abyssal peridotites from the Doldrums Fracture Zone, Mid Atlantic Ridge. Clinopyroxenes have been separated and analyzed through MC-ICP-MS techiques. The data reveal heterogeneus Nd-Hf isotopic compositions and suggest that the peridotite can be grouped into residual peridotites and melt-modified (refertilized) samples. The refertilized peridotites preserve highly radiogenic Hf values (ƐHf up to 101) associated with MORB-like Nd isotopes (ƐNd up to 12), reflecting partial resetting of ancient highly depleted mantle by recent melt-rock interaction. On the other hand, the residual peridotites have Nd-Hf isotope ratios similar to the local MORB (ƐNd = 7-12 and ƐHf =12-19),which most likely reflect highly depleted mantle that has been entirely reset by reaction with extracted or retained melts, and hence developed with only modest incompatible element depletion until recent melting at the Mid Atlantic ridge axis. These data are used to infer that the upper mantle exposed in this portion of Atlantic formed by a combination of ancient melting and melt-rock reaction processes, preceding its emplacement below the present-day Mid Atlantic ridge axis.