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 ¹⁴C ages and oxygen and carbon isotopes of planktonic foraminifera <em>N. pachyderma</em> sin. Both authigenic ¹⁰Be and ⁹Be 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 ⁹Be record. The ¹⁰Be stratigraphy also reveals a paleomagetic excursion at 45 kyr which is comparable to other records. At depths from 22 to 25 cm, the lowest ¹⁰Be 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 10Be could be due to ice cover, and is correlated with δ¹⁰O 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.