Barium peridotite xenoliths

In summary, amphibole, along with mica, is the dominant silicate host for niobium in peridotitic xenoliths. In mica-absent assemblages amphibole also dominates the barium and tantalum budgets (Ionov et al, 1997 Eggins et al, 1998) and its presence strongly alfects the bulk rock Zr/Nb ratio. 

Ionov et ai, 1997). Both strontium and barium are higher in amphibole from xenoliths than those from massif peridotites (e.g., Vannucci et al, 1995). Numerous ion-probe and laser/solution ICP-MS smdies have found wide variation in amphibole REE patterns depending on textural context and tectonic setting (Witt- Eickschen and Harte, 1994 Vannucci et al., 1995 Ionov and Hofmann, 1995 Johnson et al., 1996 Chazot etal., 1996 Vasellieta/., 1995 Ionov eta/., 1997 Pearson and Nowell, 2002 Gregoire et al., 2002). 

---