Millennial‐scale environmental changes in the northwestern Japan Sea during the last glacial cycle

Abstract

High-resolution analyses of pollen and diatoms in core LV 53-29 from the northwestern Japan Sea trace climate, vegetation and oceanographic changes during the past 120 ka. The age model for the core was based on tephrochronology, colour lightness and magnetic susceptibility and was used to aid correlation with Dansgaard-Oeschger cycles (warm Greenland interstadials (GIs) and cold Greenland stadials (GSs)). The palynological and diatom data from this core record the changing influences of the East Asian monsoon, eustatic fluctuations in sea level, and the impact of variations in the direction and intensity of marine currents. Increases in Quercus and Cryptomeria pollen reflect GIs. The highest values of Cryptomeria were recorded during Marine Isotope Stage (MIS) 5 and were associatedwith an increase in the intensityof the summer monsoon. The increase in Larix pollen is an indicatorof GSs, and it occurs in all marine isotopic stages. Changes in diatom records indicate that oceanographic conditions in the northwestern Japan Sea differed from its southern and eastern regions. An increase in the cold-water and polyhalobous Rhizosolenia hebetata indicates GIs, although the surface water temperatures were colder than today with normal salinity. Species of the genus Chaetoceros, which is characteristic of GSs, were abundant during MIS 2. The predominance of Chaetoceros taxa and the high total abundance of diatoms may reflect regional upwelling conditions. The absence of brackish-water species at this time indicates a slight freshening of the surface water. The study of pollen, spores and diatoms in sediments from the northwestern Japan Sea illustrates the great potential of these proxies for identifying abrupt climate oscillations preserved in high-temporal resolution marine records, particularly those related to interstadial and stadial conditions.

Palaeoenvironmental records from Siberia and the Russian Far East – contributions from DIMA Network members – Introduction

“…Evstigneeva et al . (2021, this issue) present the first record of diatoms and pollen from the northwest Japan Sea, which records changes in currents and sea temperatures over the past 120 ka, and highlights monsoonal influences on the region throughout the last glacial–interglacial cycle. Moving on shore, Lozhkin et al .…”

“…2021, this issue); 4 = core LV 53‐29 Japan Sea (Evstigneeva et al . 2021); 5 = Lake Latvia (Lozhkin et al . 2021, this issue); 6 = various sites in Kamchatka (Payne et al .…”

Изменение Окружающей Среды Северо-Западного Сектора Японского Моря В Период Последней Дегляциации

“…В данной работе мы детально исследовали верхнюю часть керна длиной 150 см, которая, согласно возрастной модели, формировалась в течение 21 тыс. лет (Evstigneeva et al, 2021). Образцы для палинологического и диатомового анализов (всего 62) отбирались через каждые 2 см с толщиной образца ≈ 1 см.…”