Structure and sedimentary formations of the northern Yana-Kolyma Fold System, Yakutia

Abstract

The structure, geodynamics, and sedimentary formations of the northern Yana-Kolyma Fold System and the adjacent part of the Verkhoyansk Fold System are considered on the basis of the published sheets of the State Geological Map on a Scale of 1: 200000, field observations of the authors, and literature sources. The important structure-forming role of the frontal uplift of the Kolyma-Omolon Superterrane that was thrust over in the northwestern direction is shown. The at-least-twofold shortening, thrust faulting, and large-scale offsets of the large blocks of the distal part of the Verkhoyansk continental margin and the Nagondzha paleotrough are related to this effect. An attempt is made to settle some debatable questions concerning the tectonic position of the Kular Uplift, the cause of the inconsistent structural patterns of the Jurassic and Triassic sequences at the southwestern margin of the Polousnyi Synclinorium, the counter vergence of folds in its northern and southern zones, the regional tectonic evolution in the Late Jurassic, and the eastward change in the composition of the heavy clastic mineral assemblages contained in the Upper Triassic and Jurassic rocks.