Characteristics and ages of tephra layers in the central Okhotsk Sea over the last 350 kyr

A sequence of 9 ash layers (tephra) found in the Middle-Late Pleistocene and Holocene sediments of the central Okhotsk Sea was established on the basis of glass chemical composition and refractive indices, grain-size distributions and heavy mineral assemblages. Five tephras were also characterized by rare earth element distributions. Volcanic sources and ages of the identified tephra were estimated based on pre-existing marine sediment core chronostratigraphy and correlation between these marine tephra deposits with geochemically similar terrestrial deposits on the Kamchatka Peninsula and adjacent Kurile Islands. Areal distributions and approximate eruptive volumes of pyroclastic material were also estimated for some of these tephras.