Landscape development in response to climatic change during Oxygen Isotope Stage 5 in the southern Siberian loess region

Jiri Chlachula, Rob A. Kemp, Catherine Jessen, Adrian Palmer, Phillip S. Toms

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Two high-resolution loess-palaeosol sections from the Ob Loess Plateau (Iskitim) and the Minusinsk Basin
(Kurtak 33) provide new detailed information on the last interglacial climate variations and landscape development
in the parkland-steppe zone of southern Siberia. The complete last interglacial sensu lato (130–74 ka BP)
records of the two sites, documented by magnetic susceptibility, grain-size, CaCO3 and organic carbon content as
proxy climatic data, and supplemented by thin-section studies, indicate several short warm and very cold intervals
correlated with OIS 5e–5a. A strongly continental warm climate culminated around the peak of the last
interglacial sensu stricto (OIS 5e) and cooler conditions occurred during the following interstadial stages (OIS 5c
and 5a), corresponding to shifts in palaeolandscape development with gradual replacement of parkland-steppe
and mixed southern taiga by boreal forest. During stadial stages (OIS 5d and 5b), the palaeolandscape was
transformed into a cold arid periglacial tundra-steppe. Evidence for a major cooling in Siberia during OIS 5d,
corroborating the palaeolimnological record from Lake Baikal, is provided by deep frost-wedge casts distorting
the OIS 5e chernozemic palaeosol, suggesting formation of permafrost shortly after the last interglacial climatic
optimum. The pedosedimentary record, reflecting the effects of syndepositional pedogenic processes, attests to a
dynamic climate pulsation during the last interglacial stage.
Udgave nummer2
Sider (fra-til)164-187
Antal sider17
StatusUdgivet - 2004
Udgivet eksterntJa