The U-Pb age of the norite-diorite intrusions of the nickel-bearing complex and their time correlations with the gabbronorites of the Mamonskii complex of the Voronezh crystalline massif

On the basis of isotopic-geochronological studies (U-Pb dating by zircon), the authors have first established the age interval of the formation of two -phase norite (2065+/-15 Ma) - diorite (3050+/-14 Ma) association of the su bvolcanic intrusions of the Elan nickel-bearing complex and of the gabbrono rites (2080+/-10 Ma) of the large (about 200 km(2)) complexly differentiate d Elan Vyaz ultramafic-mafic pluton of the Mamonskil complex. Besides the d ominant zircon syngenetic to diorites, these rocks contain populations whic h, by crystal-morpho logical features, uranium content, and age (2090+/-11 Ma), are very close to the zircon from the pluton gabbronorites. These data confirm the earlier results of the U-Pb dating (by zircon) of the differen tiated ultramafic-mafic plutons of the Mamonskii complex (2100-2070+/-15 Ma ), whose formation preceded the formation of the norite-diorite intrusions of the Elan complex of the Voronezh crystalline massif.