New Data on Permian Bivalves and the Age of the Volcanogenic Beds of the Arman-Viliga Folded Zone, Northeastern Asia

Abstract

Taxonomic data on Permian bivalve mollusks and the structure of the middle part of essentially volcanogenic section on the Nyavlenga River in the northeastern Okhotsk Region, Armano-Viliga Folded Zone are reported for the first time. Fossil fauna is composed exclusively of Inoceramus-like bivalves of the genera Kolymia, Cigarella, Okhotodesma, and Maitaia, which frequently form shell rocks and date the Bocharian Horizon (upper part of the Wordian Stage) as the Middle Permian. Lithologic and paleontological characteristics of the beds are considered; it is shown that volcanites are widespread; turbidites and diamictites similar to those previously investigated in the Okhotsk and Ayan-Yuryakh basins are recorded. Permian kolymiids are figured.