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Russian Geology and Geophysics

2008 year, number 6

PEAT BIOSTRATIGRAPHY AND HOLOCENE CLIMATE IN THE NORTHWESTERN MOUNTAIN PERIPHERY OF LAKE BAIKAL

E.V. Bezrukovaa,b, A.V. Belovc, P.P. Letunovaa,b, A.A. Abzaevaa,b, N.V. Kulaginad, E.E. Fisherc, L.A. Orlovae, E.V. Sheiferf, V.I. Voronin f
a Institute of Archaeology and Ethnography, Siberian Branch of the RAS, 17 prosp. Lavrentieva, Novosibirsk, 630090, Russia
b Institute of Geochemistry, Siberian Branch of the RAS, 1a ul Favorskogo, Irkutsk, 664033, Russia
c Institute of Geography, Siberian Branch of the RAS, 1 ul. Ulan-Batorskaya, Irkutsk, 664033, Russia
d Institute of the Earth's Crust, Siberian Branch of the RAS, 128 ul. Lermontova, Irkutsk, 664033, Russia
e Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
f Siberian Institute of Plants Physiology and Biochemistry, Siberian Branch of the RAS, 132 ul. Lermontova, Irkutsk, 664033, Russia
Keywords: Mountain ecosystems; biostratigraphy; dated paleoenvironmental records; Holocene; regional paleoclimate correlations
Pages: 413-421

Abstract

We report new radiocarbon ages, pollen stratigraphy, and botanical composition of an organic sediment sequence from mountains along the northwestern side of Lake Baikal. The calendar age of the peat is ca. 9.5 kyr BP. The pollen spectra between 9.5 and 8.5 kyr ago show vegetation consisting mostly of open larch and spruce-larch forests with minor birch. The interval from 7.5 to 6.8 kyr BP is marked by broad fir spread confirmed also by the peat botanical composition. The climate inferred for the period of fir dominance combines mild winters, cool summers, thick snow cover, and abundant moisture, apparently due to more intense North Atlantic air transport. Fir percentages decrease dramatically after 6.8 kyr BP, when pines begin to spread in the Baikal watershed. The peat record bears imprint of North Atlantic cooling events identified as intervals of ice-rafted detritus deposition and low surface water temperatures. The new data allow a better insight into the regional climate and landscapes, and the reliable age model provides regional and inter-regional correlations of global change events.