Geochemical features of zircons from migmatites of the Nimnyr block, Aldan shield

Abstract

This paper reports the results of chemical and structural study (electron microscopy and ion microprobe) of zircons from different-age generations of migmatite leucosomes in the basement rocks and Kurumkan Formation within the Nimnyr block, Aldan shield. The studied zircons show REE distribution pattern with a positive slope from LREE to HREE and positive Ce anomaly, which is typical of magmatic zircons, but have elevated LREE contents, which implies their crystallization from migmatite melt with subsequent fluid reworking. The transformations of the zircons were caused by fluid, which was separated during crystallization of the last LILE-enriched portions of the melt and inherited the geochemical features of the host rock—leucosome.