Phlogopite peridotite xenoliths

Cr-poor variety widespread, locally abundant (e.g.. Monastery). Garnets, clino- and orthopyroxenes, phlogopite and ihnenite most common, zircon and olivine rarer. Debatable whether phlogopite and olivine are members of Cr-poor suite. Wide range in chemistry but Cr-poor, Fe-Ti-rich relative to type I (low-Z) peridotite minerals. Mineral chemistry and estimated equilibration P/Ts overlap those of type V (high-Z) Iherzolites. Some Slave craton Cr-poor megacrysts show mineral chemistry links to type II megacrystalline pyroxenite xenoliths. See review of Schulze (1987). 

Gregoire M., Bell D. R., and Roux A. P. L. (2002) Trace element geochemistry of phlogopite-rich mafic mantle xenoliths their classification and their relationship to phlogopite-bearing peridotites and kimberlites revisited. Contrib. Mineral. Petrol. 142, 603-625. 

The Cr-diopside series is the most abundant type of xenolith found in alkali basalts. Amphibole is uncommon in samples of this series, but rare examples have been found from locations across the world (see review by Kempton, 1987). The amphibole is typically a chromium-rich pargasite and has been observed to constitute up to 6% of the mode. Commonly, these amphiboles have partially broken down, a process interpreted to be a response to the incorporation of the xenolith into the ascending host magma. Phlogopite seems to be less commonly observed in spinel peridotites, but is present along with amphibole in some suites (Kempton, 1987 and references therein). In other suites, phlogopite is the only hydrous phase present (Francis, 1987 Canil and Scarfe, 1989). 

The Al-augite series occurs either as discrete xenoliths, or as veins cross-cutting Cr-diopside series peridotite. They are usually interpreted to be high-pressure segregations from hydrous mafic melts. At many locations, the Al-augite series characteristically contains a kaersutitic amphibole and phlogopite (see review by Kempton, 1987). 

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