Postdoctor SU Benxun and his teacher report the occurrence and characteristics of sapphirine in a mantle-derived xenolith from the Cenozoic basalts of Hannuoba in the North China Craton.

The rare occurrence of sapphirine in a mantle-derived xenolith therefore suggests specific bulk composition, restricted P-T range and possible melt-peridotite interaction. Such conditions are best satisfied in a tectonic setting with basaltic magma underplating and interaction between the infiltrating melts and the wall-rock peridotite.

Figure 1. Photographs of the Hannuoba clinopyroxenite. (Image by SU)

Figure 2. (a) P-T diagram showing the equilibrium curves of sapphirine-related reactions.(b) Schematic diagram showing the distribution of rock-types and inferred lithospheric mantle structure beneath Hannuoba.(Image by SU)

Su et al. The genesis of mantle-derived sapphirine. American Mineralogist. 2012, 97(5-6): 856-863 （Download Here）