North Atlantic abrupt climatic events of the last glacial period recorded in Ukrainian loess deposits

摘要

Loess deposits are widely distributed in the Northern Hemisphere, where theyhave recorded not only the glacial-interglacial cycles, but alsomillennial-timescale changes resembling those in marine and ice cores. Suchabrupt variations are clearly marked in western European series, but havenot yet been evidenced in the East of the continent. Here we present resultsof the high-resolution investigation of a Weichselian Upper Pleniglacialloess sequence (~38–15 ka) from Stayky, Ukraine. The stratigraphyshows an alternation of loess horizons and embryonic soils, similar tosequences from western Europe. Similarities are also found betweenvariations of a grain-size index (ratio between coarse and fine materialfractions) in Stayky and in western European profiles. Based on thesesimilarities and in agreement with the luminescence dates, the embryonicsoils are associated with the Greenland interstadials (GIS) 7 to 2, and theVytachiv paleosol at the base of the sequence, with GIS 8. Pollen analysisindicates a wetter climate for these interstadials, allowing the developmentof arboreal vegetation, than for the stadials, which are marked by loess formation.The grain-size index reaches the highest values for intervals correlatedwith the Heinrich events 3 and 2. Thus, it appears that the North Atlanticabrupt climate changes have extended their influence and modulated the loesssedimentation at least as far as eastern Europe. This result is supportedby recent climate modeling experiments and recommends the Stayky sequenceas a reference for further comparisons between profiles along the Eurasianloess belt centered at 50° N.