Variability in landscape and lake system responses to glacial and interglacial climates during the Middle Pleistocene based on palynological and geochemical data from Lake El'gygytgyn, Eastern Arctic

Abstract

Palynological and elemental geochemical data from the Lake El'gygytgyn sediment core indicate that differences occur not only between cool and warm periods of the middle Middle Pleistocene (~374–790ka) but also when comparing glacial-to-glacial and interglacial-to-interglacial intervals. The magnitude and/or timing of lake and landscape responses are at times similar (e.g., MIS 11, MIS 15) and at other times different (e.g., MIS 13), suggesting a complexity of feedbacks within and between the lake and landscape. Within-stage variations in the geochemistry likely reflect shorter-term shifts in regional climate, local vegetation cover, sediment input, and/or within-basin interactions of biological and physical systems. The palynological data indicate that each interglaciation has its own specific vegetation history including differences in early interglacial vegetation and in the type and timing of climax vegetation. Cooler intervals, while showing fewer changes in plant communities, do indicate greater variability in vegetation as compared to younger glaciations, including the persistence of Larix. While changes in the proxy data generally approximate shifts in the δ18O record, a large discrepancy occurs in the timing of the MIS 10–MIS 11 transition, suggesting that the Lake E age model needs adjustment. The variety of responses within the Lake E record to large-scale forcings (e.g., orbital parameters, ice extent) provides an opportunity to further explore regional responses of arctic environments to a broad range of paleoclimatic conditions.