Orthopyroxenes cratonic mantle

The effects of post melt-depletion interaction with fluid or melt components in the lithospheric mantle has been extensively documented (e.g. Menzies Hawkesworth 1987, and references therein Harte et al. 1993 Pearson 1999 ) and it is widely accepted that these phenomena dominate the minor element geochemistry of cratonic peridotites. Extensive studies of the effect of metasomatism on the major element chemistry of lithospheric peridotites have also been made (Boyd Mertzman 1987 Keleman et al. 1992, 1998 Walter 1999). To date, most of the discussion has centred around the apparent excess of orthopyroxene, especially in Kaapvaal peridotites. However, major and trace element studies show that it is likely that the abundances of garnet and clinopyroxene are also grossly affected (Burgess Harte 1999 Shimizu 1999). 

Boyd, F. R. 1996. Origins of peridotite xenoliths major element considerations high pressure and high temperature research on lithosphere and mantle materials. Proceedings of the International School of Earth and Planetary Sciences, Siena, 89-106. Boyd, F. R. 1997. Correlation of orthopyroxene abundance with the Ni-content of eoexisting olivine in cratonic peridotites. EOS Transactions, American Geophysical Union, 78, 746. 

---