Zirconium peridotite xenoliths

Clinopyroxene shows a range of REE patterns from extremely enriched to very depleted TREE signatures (Figure 22). Noncratonic peridotites are subdivided on the basis of clinopyroxene REE patterns into LREE-depleted (type lA) and LREE-enriched (type IB Menzies, 1983 Figure 17). LREE-enriched type IB pyroxenes are the norm in most suites. LREE-depleted varieties are relatively scarce. Very few clinopyroxenes show simple LREE-depleted REE patterns that can be interpreted solely in terms of melt depletion, i.e., LREE depletion, fiat, unfractionated MREE-HREE patterns (e.g., UM-6 or 2905 Eigure 22). For peridotites that do have LREE-depleted clinopyroxenes, a correlation of HREE with other incompatible trace elements (e.g., yttrium, strontium, zirconium) in xenoliths suites worldwide requires fractional melting to be the principal means of depletion in the mantle (Norman, 2001). 

---