Geochemical Constraints on the Petrogenesis of Diamond Facies Pyroxenites from the Beni Bousera Peridotite Massif, North Morocco

The pyroxenite-diamond connection

“…In the Beni Bousera peridotite massif of Morocco there are frequent veins and lenses of pyroxenite, with or without garnet. That these rocks have been subjected to high pressure (>4.5 GPa) is evidenced by the presence in the pyroxenites of graphite pseudomorphs after diamond (Pearson et al, 1993). Boundaries between pyroxenite and peridotite are generally sharp and pyroxenite veins are often layered with margins of orthopyroxenite or websterite, consistent with Figure 3 and our experiments.…”

Partial melting of secondary pyroxenite at 1 and 1.5 GPa, and its role in upwelling heterogeneous mantle

“…If pyroxenite-derived melts are able to percolate and impregnate the adjacent peridotite, they are expected to form orthopyroxene-and clinopyroxene-enriched peridotites (e.g., Lambart et al 2012). Similar peridotites, refertilized by interaction with pyroxenite-derived melts, have been documented in various natural case studies (e.g., Pearson et al 1993;Rivalenti et al 1995;Varfalvy et al 1996; GV10 (this study) MM3 (Falloon et al 1999(Falloon et al , 2008 Robinson et al (1998) Page 19 of 24 _####_ Zanetti et al 1996;Mukasa and Shervais 1999;Bodinier et al 2004;Borghini et al 2013). Along the adiabatic upwelling of such heterogeneous mantle, this metasomatic process is likely to be continuous, as documented by experimental works on peridotiteeclogite reaction (Yaxley and Green 1998;Rosenthal et al 2014).…”

Re–Pt–Os Isotopic and Highly Siderophile Element Behavior in Oceanic and Continental Mantle Tectonites

“…Some peridotite 199 massifs contain abundant pyroxenite layers which sometimes carry chemical and isotopic 200 evidence for the significant presence of recycled crust components (e.g., Beni Bousera, Ronda, 201 Bohemian massif; Pearson et al, 1991aPearson et al, , 1991bPearson et al, , 1993Becker, 1996aBecker, , 1996b. Such compositions 202 only occur in mantle tectonites from areas that may have undergone lithospheric delamination 203 and previous episodes of subduction.…”