RESULTS OF U-Pb DATING OF ZIRCON AND BADDELEYITE FROM THE NORIL'SK-1 ULTRAMAFIC-MAFIC INTRUSION ( Russia )
K.N. Malich a,b, I.Yu. Badaninaa, E.A. Belousovab, and E.V. Tuganovac
a A.N. Zavaritsky Institute of Geology and Geochemistry, Uralian Branch of the Russian Academy of Sciences, Pochtovyi per. 7, Ekaterinburg, 620075, Russia
b The ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Macquarie University, Sydney, Australia
c A.P. Karpinsky Geological Research Institute (VSEGEI), Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Zircon, baddeleyite, U-Pb age, Noril'sk-1 ultramafic-mafic intrusion, protracted evolution
Pages: 123-130
Abstract
We present for the first time the mineralogical and isotope-geochemical pecularities of zircon and baddeleyite from various rocks of the economic ore-bearing Noril'sk-1 intrusion located in the northwestern part of the Siberian Platform. The ultramafic-mafic Noril'sk-1 intrusion hosts one of the world's major economic platinum-group-element(PGE)-Cu-Ni sulphide deposits.
A detailed study of crystal morphology and internal structure identify four zircon populations characterized by different U-Pb (SHRIMP-II) ages. The U-Pb ages of baddeleyite and the defined zircon populations cover a significant time span (from 290 ± 2.8 to 226.7 ± 0.9 Ma). The established U-Pb ages imply that crystallization of baddeleyite and zircon populations corresponds to several stages of protracted evolution of the ore-forming magmatic system (290 ± 2.8, 261.3 ± 1.6, 245.7 ± 1.1, 236.5 ± 1.8, and 226.7 ± 0.9 Ma, respectively) that served as a favorable factor for the accumulation of magmas and ores of unique scales and concentrations.
|
