Ecostratigraphy and the North Pacific Neogene Holarctic

Abstract

The stratigraphic subdivisions of the North Pacific Neogene Holarctic appear to be units recognized on an ecostratigraphical basis. The entire Far- and North East territory can be assigned to a large ecosystem including the Northeast Asia margin and the adjacent basin of the North Pacific boreal area. The Far East Neogene horizons are sometimes subdivided into finer units; ie, beds with fauna. In the West Kamchatka region 30 Neogene sedimentary cycles and 25–28 beds with fauna have been found. They reflect changes in paleogeographic conditions. The present task is to identify these units in all of the Far East provinces and to correlate them with cycles in ocean sediments. Important data are also provided by seismostratigraphy. Paleoclimatic signals are some of the best markers for correlation. A scheme of Neogene events consisting of 10 types of faunas, 3–4 climatic optima, 3 large sedimentary cycles, and 3 volcanic cycles is suggested for the Far East Neogene.