New data on the stratigraphy of the landward slope of the Japanese Trench

Results of the ecostratigraphic analysis using statistical data handling of radiolarian fauna from the sections of holes 434, 434A, 434B firstly allow us: 1) to identify the stratigraphic succession and some hiatuses in the hemipelagic sedimentation, 2) to determine the age of basal layers of the sedimentary cover as an Oligocene-Early Miocene boundary. These results present a new data on the age and environmental conditions of the formation of the sedimentary cover on the landward slope of the Japanese Trench. The “layers with radiolarians” correspond to previously established areas. The boundaries of “layers with radiolarians” marked by radiometric dates obtained on sections of the Japan Sea on transect: holes 436, 439 and 584. These results revealed the periodicity of the sedimentation process.