Trace elements peridotite xenoliths

Jochum K. P., McDonough W. F., Pahne H., and Spettel B. (1989) Compositional constraints on the continental lithospheric mantle from trace elements in spinel peridotite xenoliths. Nature 340, 548-550. 

Ionov D. A., Bodinier J.-L., Mukasa S. B., and Zanetti A. (2002) Mechanisms and sources of mantle metasomatism major and trace element compositions of peridotite xenoliths from Spitsbergen in the context of numerical modelling. J. Petrol. 43, 2219-2259. 

Studies of mantle xenoliths have confirmed the view from seismology that peridotite is volumetrically the dominant component of the Earth s shallow mantle (<400 km) (see Chapter 2.02). This is because xenolith suites in almost all tectonic environments are dominated by peridotites. Even at localities where other lithologies such as eclogite dominate the intact xenolith suite, mineral concentrate studies show that peridotite dominates the inventory of entrained mantle material (Schulze, 1989). Major- and trace-element studies of mineral concentrates from mined kimberlites have also been used to illustrate... 

Mass-balance inversion of a suite of noncratonic type 1 xenoliths from SE Ethiopia (Bedini and Bodinier, 1999) show that the trace-element composition of some whole-rock peridotites may be controlled by five distinct components ... 

Modeling of the whole-rock and mineral trace-element compositions in xenoliths that have experienced metasomatic infiltration of melts led Ionov et al. (2002a) to conclude that the REE and HFSE element compositions of peridotites adjacent to veins bear the chemical fingerprints of the metasomatic agent closest to its source (e.g., a melt vein). Further away, signatures are increasingly dominated by fractionation processes related to melt percolation. 

Table 9 Representative trace element analyses of minerals from 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). 

Bedini R. M. and Bodinier J. L. (1999) Distribution of incompatible trace elements between the constituents of spinel peridotite xenoliths ICP-MS data from the east African rift. Geochim. Cosmochim. Acta 63, 3883-3900. 

Glaser S. M., Foley S. F., and Gunther D. (1999) Trace element compositions of minerals in garnet and spinel peridotite xenoliths from the Vitim volcanic field, Transbaikalia, eastern Siberia. Lithos 48, 263 —285. 

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. 

Ionov D. (1998) Trace element composition of mantle-derived carbonates and coexisting phases in peridotite xenoliths from alkali basalts. J. Petrol. 39, 1931 — 1941. 

Ionov D. A., Dupuy C., O Reilly S., Kopylova M. G., and Genshaft Y. S. (1993b) Carbonated peridotite xenoliths from Spitsbergen implications for trace element signature of mantle carbonate metasomatism. Earth. Planet. Sci. Lett. 119, 283 -297. 

Stosch H. G. and Lugmair G. W. (1986) Trace element and Sr and Nd isotope geochemistry of peridotite xenoliths from the Eifel (West Germany) and their bearing on the evolution of the sub-continental lithosphere. Earth Planet. Sci. Lett. 80, 281-298. 

---