LATE ARCHEAN INITIAL POTASSIC MAGMATISM OF THE ALDAN SHIELD (UKDUSKA MASSIF): EVIDENCE FROM U-PB SINGLE ZIRCON DATING

Abstract

The presented geochronologic and geochemical data provide full evidence for the following conclusions. 1) The obtained age estimate (2719±14 ma) corresponds to crystallization period for the rocks of the layered series of Ukduska massif, thus these rocks for today are the oldest potassic-ultrapotassic rocks of Aldan Shield and Siberian craton. 2) The massif rocks represent the age and material analogues of the Late Archean alkaline rocks of Canadian Shield and material analogues of Phanerozoic potassic magmatites of Aldan Shield and Italy. 3) Geochemical peculiarities (enrichment with lithophilic elements along with deep negative Nb and Ta anomaly) can imply the formation of the massif rocks' parental melt resulted from interaction of enriched plum source with supersubduction mantle wedge.