海洋マントルの Sr-Nd 同位体組成

This article reviews studies on fundamental question, whether oceanic peridotite can be the source of oceanic crust or the residue left after formation of oceanic crust, using a radiogenic isotopic composition from the 1990s. The Sr-Nd isotopic compositions of the oceanic peridotite are highly heterogeneous compared to those of the oceanic crust. The wide isotopic variation cannot be explained by simple partial melting or interaction between melt and peridotite. It requires several stages of ancient partial melting and interaction with melt. It has been suggested that the Sr-Nd isotopic compositions of the oceanic crust are homogenized by partial melting of the heterogeneous mantle peridotite. Accumulation of Sr-Nd isotopic data of the oceanic peridotites will be useful to further decipher the processes of partial melting and/or melt-peridotite interaction which occurred through the Earth's history.