Experimental study of the P-T stability of phlogopite in metasomatised peridotite with varying H2O contents in the deep cratonic lithosphere

Phlogopite is an important metasomatic, hydrous, potassic phase in peridotite from on- and off-cratonic lithospheric mantle. It is significant in the petrogenesis of mantle-derived magmas, including micaceous kimberlites, ultramafic lamprophyres, kamafugites, lamproites, which are all potential sources of diamonds.

We lack experimental investigations close to the limits of phlogopite stability in a model mantle composition enriched in K with varying amounts of H2O from 4 to 9 GPa (120 to 300 km). Variations in the %H2O available determine the shape and location of the solidus, and hence the onset of partial melting of a K-enriched mantle.

The study will determine the stability fields of phlogopite in the Earth upper mantle as a function of P, T, and bulk %H2O, using the large volume press at ID06 in combination with in-situ XRD.

The study will contribute to more complete modelling of the lithosphere-asthenosphere boundary of a metasomatised mantle enriched in K and H2O.