Inefficient melt mixing below a fast-spreading ridge revealed by Hess Deep lower gabbros (ODP Leg 147 and IODP Expedition 345).

ABSTRACT: The oceanic crust crystallizes from melts formed within a heterogeneous mantle source, which is mostly composed of variably depleted peridotites and recycled crust. Yet, the compositional variability of this mantle source and the progressive aggregation of heterogeneous melts during extraction are poorly constrained. Here, we show that in situ isotopic analyses in gabbros formed at the East Pacific Rise retain substantially greater Sr-Nd-Hf isotopic heterogeneity than basalts erupted along the fast-spreading ridge. This implies that melt aggregation during migration through the upper mantle and lower crust is inefficient, even at magmatically productive spreading ridges; efficient melt mixing likely occurs in the overlying axial melt lens. Local isotopic heterogeneity of Hess Deep gabbros

SUBMITTER: Basch V 

PROVIDER: S-EPMC12007581 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature