New Data on Volcanism of the Central Chukotka Segment of the Okhotsk-Chukotka Volcanogenic Belt

摘要

New geochronological and geochemical data on the age and composition of undifferentiated Cretaceous volcanics from the Palyavaam River basin, Central Chukotka region, are presented. These data indicate the heterogeneity of rocks of the Etchikun Fm., which are divided into two groups. Andesites of the first group (Etchikun Fm. proper) are of early Cretaceous age and represent a magmatic phase preceding the formation of the Okhotsk-Chukotka volcanogenic belt (OChVB). Andesites of the second group correlate well in age and composition to the OChVB volcanic rocks. They occur at the base of the Chauna Series of the OChVB and indicate the homodromous character of the evolution of volcanism in the Central Chukotka sector of the OChVB.