Rare Earth Element Distribution in a Metasomatic Zoned Ultramafic Pod from Fiskenaesset, West Greenland

M. B. Fowler, C. T. Williams and P. Henderson
Department of Geology, Imperial College, London SW7 2BP
Department of Mineralogy, British Museum (Natural History), London SW7 5BD

Abstract: The distribution of REE in a zoned ultramafic pod formed by incomplete re-equilibration of ultrabasic and quartzofeldspathic reactant compositions has been studied. Transport of the heavy REE (HREE) as well as the light REE (LREE) over several metres has occurred during the diffusion-controlled metasomatism of the protolith mineral assemblages. The largest resultant concentration range (Eu) exceeds two orders of magnitude. In general, REE abundances increase towards the marginal zones, and differences between the behaviour of LREE, middle REE (MREE) and HREE subgroups are observed. LREE are least mobile in the aqueous transporting medium. Complexing by carbonate ligands is probably not an important factor in this system, and the final REE distribution is thought to be governed largely by the crystal structure of the major zonal minerals.

Mineralogical Magazine; December 1983 v. 47; no. 345; p. 547-553; DOI: 10.1180/minmag.1983.047.345.16
© 1983, The Mineralogical Society
Mineralogical Society (www.minersoc.org)