Aptian-Albian coaliferous sediments of Kotel’nyi Island (New Siberian Islands): New data on the section structure and ignimbrite volcanism
The Aptian-Albian sediments of Kotel’nyi Island are represented by a terrigenous coaliferous complex with the apparent thickness of approximately 700 m. The upper two thirds of their section enclose ignimbrites and rhyolitic ash tuffs. The integral thickness of volcanics is 170 m. A new sequence composed largely of acidic volcanics and sedimentary rocks is defined in the upper part of the Cretaceous section. The K-Ar age estimated for ignimbrite glasses is 110–107 ± 2.5 Ma, which corresponds to the first half of the Albian. The fossil flora list is added by several previously unknown forms. The macroflora of Kotel’nyi Island is similar to its Albian counterpart from the Kolyma-Indigirka region and allows Cretaceous sediments from the lower part the Kotel’nyi Island section to be dated back to the Aptian (?)-Albian (except for the terminal Albian). The palynological characteristic of rocks immediately contacting the dated volcanics appeared to be untypical of Albian sediments of Siberia and similar to that of the Late Neocomian palynocomplexes. This is partly explained by erosion and reworking processes. The examined continental sediments accumulated in post-orogenic extension settings. They constitute the lower strata of the Aptian(?)-Tertiary post-orogenic complex filling riftogenic depressions in the New Siberian Islands and Laptev Sea.