Trace Element Geochemistry of Zircons from the Early Paleozoic Granites of the Angara–Vitim Batholith

—Analysis of zircons from Early Paleozoic calc-alkaline granitoids in the central part of the Angara–Vitim Batholith revealed two geochemically different zircon varieties. Central unaltered domains have homogenous BSE images, “magmatic” REE distribution pattern, and the moderate content of trace elements. Altered zones of zircon are characterized by more gentle patterns owing to the growth of LREE and MREE, as well as by the elevated contents of U, Th, Ca, Sr, and Ba. Such compositional peculiarity could be related to the influx of fluid, which caused a metasomatic alteration of granites during their microclinization. Geochemical features of zircons, together with their internal structure, should be taken into account during geochronological study of zircon.