| Summary: | To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El’gygytgyn in northeast Arctic Russia. Sedi- ments from this lake contain a paleoclimate record of glacial- interglacial cycles during the last three million years. Low- resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical param- eters are used to infer past climatic conditions thus provid- ing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Follow- ing this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differ- ences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.
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