Late Quaternary climate and environmental reconstruction based on leaf wax analyses in the loess sequence of M?hlin, Switzerland

摘要

We present the results of leaf wax analyses (long-chain n-alkanes) from the 6.8 m deep loess sequenceof M?hlin, Switzerland, spanning the last ～ 70 kyr. Leaf waxes are well preserved and occur in sufficient amounts only down to 0.4 m and below 1.8 m depth, so no paleoenvironmental reconstructionscan be done for marine isotope stage (MIS) 2.Compound-specific δ2Hwax analyses yielded similar values for late MIS 3 compared to the uppermost samples, indicating that various effects (e.g., more negative values due to lower temperatures,more positive values due to an enriched moisture source) cancel each other out. A pronounced ～ 30 ‰shift towards more negative values probably reflects more humid conditions before ～ 32 ka. Radiocarbon dating of the n-alkanes corroborates the stratigraphic integrity of leaf waxes and their potentialfor dating loess–paleosol sequences (LPS) back to ～ 30 ka.