10Be and 10Be/9Be in glaciomarine sediments of Ross Sea, Antarctica: implications for mid-late Quaternary paleoenvironmental changes

Abstract

This study documents the variation of Be isotopes (10Be and 9Be) and their ratio (10Be/9Be) from a Ross Sea sediment core (LC42) with relation to mid to late Pleistocene geomagnetic and paleoclimatic changes. Significant changes in Be isotope concentration are observed during pre and post-Mid-Pleistocene Transition (MPT) periods. The 10Be concentration and 10Be/9Be ratio show a gradual decrease during the late Matuyama Chron, suggesting a relative increase in geomagnetic intensity. The overproduction episode associated with the Matuyama-Brunhes Boundary (MBB) does not show any pre- MBB precursor event. The progressively decreasing trend observed in 10Be and 10Be/9Be ratio records from 1 to 0.8 Ma, with minimum values at around 0.8 Ma, suggests a relatively open sea condition during the early part of MPT and an extended glacial condition around MIS 22. The 10Be and 10Be/9Be ratios are approximately constant during the pre-Mid Bruhnes Event (MBE) period and show a gradual increase after the MBE, indicating a climatic transition from colder (pre-MBE) to relatively warmer (post-MBE) conditions.