Geologija / Geology
 ISSN 1392-110X ISSN 2029-056X (online) |
2005 m. Nr. 1 Results of palynological analysis of Bedoba section
(Late Pleistocene of Middle Siberia)
The constrative alluvium of the Bedoba section (Northern Priangarie) was studied palynologically. The uranium–thorium (U/Th) date is 120 ± 13 ka (Kazantsovian =Mikulian = Eemian = Merkine time) for the oxbow-like peat bog of this section and for the secondary pond facies in the upper layer of the constrative alluvium. The 14C
date, 52100 ± 1680 years (LU-5044), shows the Zirianian time (Early Valdaian = Early Vistulian = Early Nemunas). Palynospectra from the upper parts of the stream alluvium to the upper part of the oxbow-like peat bog reflect the evolution of the southern-taiga forests with Corylus, Tilia and Quercus admixture. These forests are near to the Kazantsovian Interglacial optimum. In oxbow-like clays which overlap the peat bog, palynospectra reflect some cooling and moistening in this interglacial end. After a long interruption of sedimentation in the first half of the Zirianian time, palynospectra of periglacial vegetation (meadows and Bryales bogs with open woodlands among the valley areas) were studied in sands of constrative alluvium. In the lower part of the secondary pond clays, palynospectra reflect the spreading of open spaces with xerophytes. In the upper part of these clays, spaces of s bogs appear, moisture increases in cool climate conditions during the Zirianian glaciation degradation. Keywords: Middle Siberia, Irkineeva River, Bedoba section, alluvium, palynology, Kazantsovian nterglacial, Zirianian Glaciation |
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