Title

A. N. Timashkov, E. I. Sergeeva, S. L. Presnyakov, E. S. Bogomolov, S. V. Kashin, Yu. S. Bal-ashova, A. O. Plekhanov, S. A. Sergeev

New data on the age of magmatic formations in the Central Aldan region

The U-Pb zircon dating of allegedly Archean ultramafic and granitic (leucoplagiogranites) rocks of the Central Aldan has been done. Earlier the latter rock wasn’t suggested an independent intrusive complex, but considered as a part of the Kamenkovsky Early Ptoterozoic complex. The geochronological study showed that the hypersthenite of the ultramafic “Archean” Early Fedorovsky complex actually intruded at 350 Ma, and later experience dynamometamorphism caused Pb-loss which resulted in apparent ages of 250 Ma. The leucoplagiogranites yielded age of 1830 ± 21 Ma, which along with their petrochemistry suggest their separation from the Kamenkovsky complex, with typically older granitoids (1933 ± 9.7 Ma). The investigated rock types have regional significance and ascertainment of their age significantly clarifies and improves serial map legends – Aldano-Zabaykalskaya (1000) and Aldanskaya (200). It is the first time when Paleozoic igneous rocks are proved in the Central Aldan, where during Early Paleozoic almost continuous sedimentation took place, and at the end intrusive magmatism began.
Key words: ultramafit, hypersthenite, zircon, plagiogranite, age, isochrona