Ice-cover History and Paleoceanographic Change of the Western Arctic Ocean (Mendeleev Ridge) using Be isotopes

Abstract

A new investigation of paleoclimate and environmental changes using beryllium isotopes in sediment from the Mendeleev Ridge of the western Arctic Ocean was accomplished using a 39 cm-long box core record. The age of core PS72/396-3 appears to date back to MIS 5.d based on the stratigraphy of beryllium isotopes and paleomagnetic data and other isotopic data of this study, AMS C ages and oxygen and carbon isotopes of planktonic foraminifera N. pachyderma sin. Both authigenic Be and Be records show that there are three major cold periods during MIS 5.d and reveals a much longer warm period after the second cold period based on Be record. The Be stratigraphy also reveals a paleomagetic excursion at 45 kyr which is comparable to other records. At depths from 22 to 25 cm, the lowest Be signal may be due to the highest paleomagnetic intensity, which is indicated as an age of 75 kyr from other records. However, a reduction in cosmogenic Be could be due to ice cover, and is correlated with δ O evidence fo a cold period. Interestingly, Be data show that constant input of Be to the Mendeleev Ridge is observed for this time period. During this time period, TOC (%) values also show a similar pattern. The record of authigenic Be is inversely correlated to that of Ca and proportional to opal production. These observations confirm that Be can also be a good proxy as a climatic tracer. This study may be a useful approach for understanding Arctic climate change.