The First Data of U/Pb and 40Ar/39Ar Dating of the Pre-Dzhugdzhur Volcanics: New Evidence of Time Diversity in the Formation of Individual Sectors of the Okhotsk–Chukotka Volcanogenic Belt

The first data of U/Pb and 40Ar/39Ar dating of volcanogenic rocks of the Pre-Dzhugdzhur volcano-tectonic trough (PDVT) of the Okhotsk–Chukotka volcanogenic belt (OChVB) confirm that the supra-subduction complexes, identical in composition and position in the geological section, were formed at different times in the main arc sector of the OChVB and adjacent flank zones. It has been established that the flank zones of the belt formed at different times as well. The main arc sector was formed with a lag of 9–11 Ma related to the Western Okhotsk flank zone and 5–8 Ma ahead related to the Eastern Chukotka flank zone. The results obtained have been analyzed along with the data on Albian magmatism of Northeastern Russia. This allowed us to suggest that the area of the future Pre-Dzhugdzhur and Ul’ya volcano-tectonic troughs was affected by active volcanism of the convergent margin regime during the Albian, when that part of the region that later became the main arc of the OChVB developed in the setting of the transformed margin.