Lithology of the Upper Triassic Sedimentary Rocks of Chukotka and Wrangel Island and Their Relationship with Coeval Rocks of the Eastern Arctic

Abstract

Abstract—The correlation between the sedimentologic characteristics of the Upper Triassic deposits of Wrangel Island and the Chukchi Peninsula (Chukotka) is discussed. These deposits are similar in isotopic, petrographic, and geochemical features. It has been established that the Upper Triassic sand strata accumulated at different sites of a single sedimentary basin, in shallow-water prodeltas of Wrangel Island and in deeper-water environments of Chukotka. In the latest Triassic, the portion of the sand component in the sections increased. At the same time, the average size of the sand grains decreased, which indicates weakening of the tectonic factor in some zones of the provenance and its general peneplanation with the formation of a weathering crust. The eroded complexes are composed of granitoid, metamorphic, and metavolcanic rocks. They stayed on land for a long time, being subjected to chemical weathering. The depth intervals with the large amount of sandy material in the section of Wrangel Island and Chukotka are correlated with those in the sections of the Sverdrup Basin and the northern slope of Alaska.