Palynological characteristics of the sediments of the Malokuril’skaya formation (Maastrichtian-Danian), Shikotan Island

A spore-pollen assemblage was established for the first time in the sediments of the Malokuril’skaya Formation (Khromova Bay, Shikotan Island, Lesser Kuril Range, Kuril island arc system). This find enabled dating of the sediments of the uppermost part of the Malokuril’skaya Formation, which, based on this data, are referred to the Maastrichtian-Danian boundary. The assemblage of radiolarian species was identified for the entire section of the Malokuril’skaya Formation. In sediments of the lower part of the section, members of the Inoceramus group were described. These findings add new information to the paleontological characteristics of the Malokuril’skaya Formation. Moreover, our work allowed detailed correlation of the palynological assemblage studied with coeval palynological assemblages of adjacent areas. The similarity of Cretaceous-Paleogene sections of the Ust-Palanskaya (West Kamchatka), Uchir (Sakhalin Island) and Malokuril’skaya Formations, the Upper Cretaceous basement and the Cenozoic cover of the underwater Vityaz Ridge support the shared history of the development of the entire transition zone from the marginal Sea of Okhotsk to the Pacific at the Maastrichtian-Danian boundary.