Abstract
Concentrations of PGE and Au of seven carbonatite samples from the Maoniuping REE deposit in China are reported (ppb): Ir 0.50∼0.78, Ru 1.61∼6.75, Rh 0.08∼0.14, Pt 2.62∼12.15, Pd 1.11∼3.65 and Au 1.24∼8.61, respectively. The primary mantle-normalized PGE distribution patterns reveal “swallow type” curve, with enrichment in Ru, Pt, Pd in comparison with Ir, Rh, and are similar to those of harzburgite in Dazhuka, Tibet, China. Nobles-metals reveal different trend with increase of Zr/Hf ratios. The preliminary study indicates that the overall PGE abundances of carbonatites are higher than the averages of MORB and OIB; the PGE of carbonatites underwent multi-source evolution. Fluids derived by metasomatism and subduction may transport PGE into carbonatite magmas. We suspect that besides the role of sulfides, volatile and alloys may modify PGE distribution patterns in carbonatite magma.
