Evidence for oxygen-conserving diamond formation in redox-buffered subducted oceanic crust sampled as eclogite.

ABSTRACT: Cratonic eclogite is the product of oceanic crust subduction into the subcontinental lithospheric mantle, and it also is a fertile diamond source rock. In contrast to matrix minerals in magma-borne xenoliths, inclusions in diamond are shielded from external fluids, retaining more pristine information on the state of the eclogite source at the time of encapsulation. Vanadium is a multi-valent element and a widely used elemental redox proxy. Here, we show that that xenolithic garnet has lower average V abundances than garnet inclusions. This partly reflects crystal-chemical controls, whereby higher average temperatures recorded by inclusions, accompanied by enhanced Na₂O and TiO₂ partitioning into garnet, facilitate V incorporation at the expense of clinopyroxene. Unexp

SUBMITTER: Aulbach S 

PROVIDER: S-EPMC8993838 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature