Stratigraphy of Late Cretaceous sediments of the eastern part of the Olyutor Trough (Koryak Plateau)
Abstract
Volcanogenic formations of Maastrichtian and probably Danian age are part of the Upper Cretaceous-Paleogene volcanogenic-siliceous formation distributed in the south of the Koryak Plateau within the Olyutor Trough. Yu. P. Ershov and G. A. Zakrzhevsky, who first described these sediments in 1956 as the Achayvayam Formation, attributed them to the Paleogene and/or Neogene. It was only in 1962 that the Maastrichtian age of the volcanogenic formations of the Achayvayam Formation was established due to faunal finds. Its upper horizons were conventionally assigned by A. V. Ditmar to the Danian Stage. Now, when the Maastrichtian fauna is known in a number of new locations, we can speak about a wide distribution of Maastrichtian sediments between the valleys of the Achayvayam and Apuka in the northwest and the Bering Sea coast in the southeast. The length of this northeasterly elongated strip is 120 km. This article is devoted to the description of the sediments developed in its northeastern part in the basins of the Kadekkun, Villeikin, Kachestan and Anivayam rivers ....
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