Neodymium amphiboles

The paradox of the spatial decoupling between isotopic contamination and LILE and LREE enrichment was resolved with a numerical simulation of isotopic variations during reactive porous flow (Bodinier et al., 2004). This confirmed that the isotopic contamination (e.g., " Nd/ " Nd) by the infiltrated melt is restricted to the domain between the melt source ( = dike) and the chromatographic front of the element (neodymium)—i.e., —20 cm from the dike in the studied wall rock. Numerical experiments also showed that the fractional solidification of infiltrated melt (due to amphibole cpx precipitation) accounts for the systematic increase in thorium, uranium, LREE, and P2O5, that reach a maximum in the distal apatite-bearing wall rock (>50 cm from the... 

One of the first studies to show this was performed on Kilboume Hole spinel Uierzolites (Jagoutz et al, 1980). Equihbrated neodymium isotopes in orthopyroxene and diopside defined essentially zero age isochrons, consistent with the very recent eruption age of the host volcanic rocks, while strontium isotopes were un-equilibrated. Stolz and Davies (1988) found varying degrees of equihbration between amphibole, clinopyroxene and apatite in peridotite xenoliths from S.E. Australia. Several samples contained coexisting amphibole and clinopyroxene and had almost reached isotopic equilibrium for strontium but displayed disequilibrium relations for lead and neodymium isotopes. This was taken to indicate more rapid diffusion of strontium than lead and neodymium. Some peridotite and eclogite... 

Compared with neodymium and strontium, there are relatively few studies of the lead isotopic compositions of mantle xenoliths and the systematics are probably biased towards samples that show some degree of patent metasomatism in the form of introduction of amphibole and/or mica. Much of the data come from noncratonic metasomatized peridotites (e.g., Stolz and Davies, 1988) and cratonic MARID xenoliths. Some type I xenoliths that do not have patent metasomatism, from cratonic and noncratonic settings (Kramers, 1977 Galer and O Nions, 1989 Walker et al., 1989 Lee et al., 1996) together with various... 

Bastnasite (CeFCOs) - a fluorocarbonate of cerium containing 60-70% rare earth oxides (REO), including lanthanum and neodymium - is the world s major source of rare earths. Host rocks include carbonatite, dolomite breccia with syenite intrusives, pegmatite, and amphibole skam. Since 1985, the bastnasite production in China has increased very fast and has dominated the market from the 1990s to the present. 

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