NEW DATA ON THE NEOGENE VOLCANO-SEDIMENTARY COMPLEX OF THE ICHA DEPRESSION: THE TYRKACHYN SECTION (WESTERN KAMCHATKA)

In the 90-m river bank of middle reaches Icha River, thick strata volcano-sedimentary deposits represented by pyroclastic rocks and siliceous tuffites with layers diatomites were studied. Representative diatom assemblages assigned to Middle Miocene Denticulopsis hyalina Zone (14.9–13.1 Ma) indicate relatively deep-water conditions marine basin. Comparison data on from reference sections Western Kamchatka indicates that Tyrkachin section belong upper part Kakert Formation. The petrographic composition lithological structure volcanogenic formations (members 1, 2, 4) suggest they are product flows associated volcanic activity in central Kamchatka. It is assumed Members 1 2 formed subaerial conditions, as indicated complete absence microfossils, signs primary stratification, layering. sediments Member 4 eroded contacts pronounced layering apparently accumulated a subaqueous setting