Pleistocene radiolarian biostratigraphy of the submarine Vityaz Ridge, Northwest Pacific

This study presents new data on radiolarian fauna from the Pliocene–Quaternary sediments of the submarine Vityaz Ridge (SVR) and the paraxial zone of the Kuril– Kamchatka Trench (KKT): 60 taxa from 32 genera of Spumellaria, 50 taxa from 34 genera of Nassellaria, and 6 taxa from 2 genera of Collodaria were observed. An analysis of taxonomic compositional of the radiolarians revealed the Pleistocene radiolarian zone assemblages Cycladophora sphaeris, Eucyrtidium matuyamai, Stylatractus universus, and Lychnocanoma sakaii on the SVR and in the paraxial zone of the KKT. We also determined geographical distributions of these zones in the North Pacific. In addition, based on our and other previously published data, we inferred that two hiatuses occurred (during the Late Pliocene and the Middle–Late Pleistocene) in the study area. We established that the southern and northern plateaus of the SVR developed in different tectonic and sedimentation regimes at the end of the Early–beginning of the Middle Pleistocene.