Changes in the content of eolian iron during the past 900 ka and the implications

Abstract

In this study, total Fe2O3 content (Fet) in two parallel sections from the central Loess Plateau (Xifeng and Changwu) is analyzed to address the variations of eolian iron in the past 900 ka. The obtained timeseries indicate that Fet values in some glacial intervals are comparable to that of interglacial periods and its oscillations do not generally correspond to the long-term glacial-interglacial changes. Rather, it exhibits higher frequency fluctuations without detectable 100 ka period, but with a strong 20 ka period and a clear 40 ka period. The combination of 20 ka and 40 ka periods suggest that eolian iron content was relatively independent of glacial-interglacial changes, but more strongly influenced by the insolation changes in the northern hemisphere. Higher iron content was observed for the S5-1 soil that is correlative to marine δ18O stage 13. In marine records, this stage is characterized by higher δ13C values, suggesting that the event is of global significance.