Spinel peridotite

Attree RW, Cabell MJ, Cushing RL, Pieroni JJ (1962) A calorimetric determination of the half-life of thorium-230 and a consequent revision to its neutron capture cross section. Can J Phys 40 194-201 Bateman H (1910) Solution of a system of differential equations occurring in the theory of radioactive transformations. Proc Cambridge Phil Soc 15 423-427 Beattie PD (1993) The generation of uranium series disequilibria by partial melting of spinel peridotite ... 

Beattie P (1993a) The generation of uraiuum series disequilibria by partial melting of spinel peridotite Constraints from partitioiung studies. Earth Planet Sci Lett 117 379-391... 

Figure 14. Inter-mineral Fe isotope fractionations among olivine and clinopyroxene from spinel peridotite mantle xenoliths. Data are from Zhu et al. (2002) ( ) and Beard and Johnson (2004) ( ). In the study by Beard and Johnson (2004), the difference in the Fe isotope composition between clinopyroxene and olivine is larger as a function of their 5 Fe values, suggesting disequilibrium fractionation.

Ottonello G. (1980). Rare earth abundance and distribution in some spinel peridotite xenoliths from Assab (Ethiopia). Geochim. Cosmochim. Acta, 44 1885-1901. 

As another example, at 10 kbar, melting of a spinel peridotite has the following melting reaction in mass units (Kinzler and Grove, 1992)... 

The distribution coefficients of the parent and daughter nuclides are important in U-series disequilibria. If the parent has a higher distribution coefficient than the daughter, its extraction from the matrix is retarded and the daughter/parent activity ratio in the melt can be greater than 1. Experiments have shown that Dy > Dj for garnet peridotites but Du experimental difficulties, Dro and Dpa are not directly known but are inferred to be very small. Therefore, it is reasonable to assume Dj, >Di and Du > Dp for both garnet peridotites and spinel peridotites. 

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. 

Alps. The Baldissero, Balmuccia, and Finero ultramafic bodies are three well-known examples of orogenic spinel peridotites in the Western Alps. They are exposed in the lowermost part of the... 

Bedini R.-M. and Bodinier J.-L. (1999) Distribution of incompatible trace elements between the constiments of spinel peridotite xenohths ICP—MS data from the East African Rift. Geochim. Cosmochim. Acta 63, 3883—3900. 

Conquere F. and Fabries J. (1984) Chemical disequilibrium and its thermal significance in spinel peridotites from the Lherz and Freychinede ultramafic bodies (Ariege, French Pyrenees). In Kimberlites II. The Mantle and Crust-Mantle Relationships (ed. J. Kornprobst). Elsevier, Amsterdam, The Netherlands, pp. 319-331. 

Garrido C. J., Bodinier J.-L., and Alard O. (2000) Distribution of LILE, REE and HFSE in anhydrous spinel peridotite and websterite minerals from the Ronda massif insights into the nature of trace element reservoirs in the subcontinental lithospheric mantle. Earth Planet. Sci. Lett. 181, 341-358. 

Lx)rand J.-P., Bodinier J.-L., Dupuy C., and Dostal J. (1989) Abundances and distribution of gold in the orogenic-type spinel peridotites from Ariege (Northeastern Pyrenees, France). Geochim. Cosmochim. Acta S3, 3085—3090. 

The modal abundances of ohvine, orthopyroxene, clinopyroxene and spinel observed for spinel peridotites from six well-characterized olf-craton xenolith suites are plotted against a depletion index in Figures 3(a)-(c). The amount of ohvine correlates negatively with degree of depletion, as expected because olivine is a product of the reaction that produces melt at the solidus (Figure 2) (see Chapter 2.08). The number of samples compiled (n = 143) may not be completely representative, but there is nonetheless a suspicious population gap at 2 wt.% AI2O3. 

Differences between the modes observed in spinel peridotite xenoliths and those predicted by experiment may result because the former are not simple residues, and have had components introduced after their original formation. 

The Fe " content in xenolith spinels is large and unlike garnet or pyroxenes can be measured reliably from electron microprobe methods (Wood and Virgo, 1989) and is useful for oxygen barometry of spinel peridotites (Wood et al, 1990 Ballhaus et al., 1991). Representative analyses from different peridotite facies are shown in Table 3. 

Figure 8 Mg/(Mg + Fe) versus Mg/Si for (a) off-craton spinel peridotite xenoliths and (b) cratonic garnet and spinel peridotite xenoliths. Arrows mark the oceanic trend (Boyd, 1989, 1997) defined by abyssal peridotites. Also shown are various estimates for primitive upper mantle (polygons from Table 7).

The best characterized noncratonic, spinel peridotite xenoliths for PGEs are those from southeastern Australia (Handler and Bennett, 1999), the Massif Central, France (Lorand and Alard, 2001), Western USA (Morgan et al., 1981 Lee, 2002) and Vitim, Siberia (Pearson et al,... 

Amphibole HFSE characteristics are sensitive to the presence of Umenite and rutile. In MARID samples where rutile dominates over Umenite, Gregoire et al. (2002) note that K-richterites display large negative niobium and tantalum anomalies, whereas when Umenite dominates, these anomalies are positive. Nb/Ta ratios of amphibole vary from close to the PUM value (17.6) up to —25 (Figirre 23). Zr/Hf values are generally lower than the PUM value of 37 (Figure 23). Differences in HFSE contents between vein and disseminated amphibole (and mica) in spinel peridotites may be explained by a model in which Zr-Nb rich amphibole and mica crystallize close to, or within a melt vein in the mantle. The fractionated, chlorine-rich aqueous residual fluids from the evolved melt then crystallize low Zr-Nb, LREE-depleted amphibole or... 

Few systematic Sr-Nd isotope studies have been performed on ocean island xenolith suites. Ducea et al. (2002) analyzed clinopyroxenes from plagioclase-spinel and spinel peridotites from Pali, (Oahu, Hawaii) and found relatively depleted strontium and neodymium isotope systematics that they interpret as representing their evolution as residues from the extraction of Pacific Ocean crust. Consistent with this is a 61 20Ma errorchron defined by the pyroxene separates that is within error of the 80-85 Ma age of Pacific lithosphere beneath Hawaii. 

There are few pubhshed Lu-Hf isotope studies of mantle xenohths because of difficulties in efficient ionization of hafnium by thermal ionization mass spectrometers. Multicollector plasma mass spectrometers are a solution to this problem and data are emerging that promise to be a more revealing tool in mantle environments than neodymium isotopes. The variety of Lu/Hf fractionation displayed by mantle minerals (Figure 42) indicates that, as with other isotope systems, isotopic variation should be considerable and initial results are confirming this. Salters and Zindler (1995) found very radiogenic Hf/ Hf at relatively unradiogenic neodymium isotope compositions in spinel peridotites from Salt Lake Crater, Hawaii. Radiogenic Hf/ Hf also characterizes low-T circum-cratonic... 

Arai S. (1994) Characterization of spinel peridotites by olivine-spinel compositional relationships review and interpretation. Chem. Geol 113, 191-204. 

Downes H. and Dupuy C. (1987) Textural, isotopic and rare earth variations in spinel peridotites xenoliths. Massif Central, Erance. Earth Planet. Sci. Lett. 82, 121-135. 

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. 

Ionov D. A. (1996) Distribution and residence of hthophile trace element in minerals of garnet and spinel peridotites an ICP-MS study. J. Conf Abstr. 1, 278. 

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