MAJOR EPOCHS OF INTRUSIVE MAGMATISM OF KUZNETSK ALATAU, ALTAI, AND KALBA (FROM U-PB ISOTOPE DATES)

Abstract

We present new U-Pb isotope dates for zircons from intrusive rocks of Kuznetsk Alatau, Gorny Altai, Rudny Altai, and Kalba and generalize the earlier published results of geochronological studies in these regions (U-Pb and Rb-Sr dates). Comparison of radiological ages with geological data permitted us to refine the scale of intrusive-magmatism events and recognize seven major epochs corresponding to a successive change of geodynamic settings: V-∈1 - accretion-subductional, related to the evolution of sea-marginal-island-arc systems of the Paleo-Asian ocean; ∈2-O1 - accretion-collisional; D1-D31 and D32-C1t - accretion-subductional, related to the evolution of active continental margin of the Andean type; C1V-C3 - accretion-collisional, related to the oblique collision of the Dzhungar microplate with the Siberian continent and closure of the Ob'-Zaisan paleoocean basin; P1-T2 - postcollisional, realized in the strike-slip fault-disjoining regime; and T3-J1 - within-plate magmatism.