Rare earth chemistry of perovskite group minerals from the Gardiner Complex, East Greenland

Abstract

AbstractPerovskite group minerals, general formulaABX3, from the intrusive ultramafic alkaline Gardiner Complex, East Greenland, range from almost pure CaTiO3(perovskite,sensu stricto), to the rare earth element (REE) variety, loparite-(Ce). Chemical zonation in the perovskites (sensu lato), is described by the substitutions 2Ca2+= (Na++REE3+) on theA-site and 2Ti4+= (Fe3++ Nb5+) on theB-site. Other trace elements detected include Th, Sr, Al, Si, Zr, Ta and Sn. Excellent agreement was found between the determinations of theREEby electron microprobe and neutron activation analysis. Chondrite-normalizedREEpatterns display enrichment in the light rare earths for perovskite, loparite, apatite, melilite and diopside. Mean perovskite/apatite partition coefficients from four of the Gardiner rocks were calculated as La = 10.4, Ce = 13.8, Nd = 13.9, Sm = 9.9, Eu = 7.7, Gd = 5.2, Tb = 5.6, Tm = 5.5, Yb = 2.7 and Lu = 1.6, indicating that perovskite concentrates allREEto a much greater extent than apatite. Light-REEenrichment occurs in both perovskite and apatite.