Variability of carbonate pedofeatures in a loess-paleosol sequence and their use for paleoreconstructions |
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| Authors: | I Kovda S Sycheva M Lebedeva S Inozemtzev |
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| Institution: | (1) Institute of Geography, Staromonetny 29, 119017 Moscow, Russia;(2) Institute of Soil Science, Pyjevsky 7, 119017 Moscow, Russia;(3) Dept. of Soil Science, Moscow State University, Leninskiye Gory, 119998 Moscow, Russia |
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| Abstract: | Carbonate pedofeatures were studied in details in a loess-paleosol pedocomplex near Kursk, in the central part of the European
Plain. The soils studied included a modern Chernozem and five Pleistocene paleosols. Carbonate morphologies and distributions
were described in the field. Various morphologies were sampled for further studies including micromorphology in thin sections
and submicroscopic studies under a scanning electron microscope. The complex approach of investigation at macro-, micro-,
and submicroscopic levels found that most of carbonate pedofeatures are secondary and multiphase. Many of them are related
to cryogenic features. The general trend was of decreasing carbonate content in the older paleosols except for increased content
in the 1st and 3rd paleosols. Most of carbonate morphologies are similar in the modern soil and paleosols, but pseudomycelium was found only
in the modern Chernozem, while soft masses and impregnations are associated with the paleosols. Detailed study on carbonate
attributes revealed their specific features in the modern soil and in paleosols. Veins have dissolution features under the
modern environment and seem to reprecipitate in form of pseudomycelium. Coatings in paleosols at a depth of the 1st paleosol include specific fine tubes. Powdery soft masses and impregnations in the paleosols are strongly related to cryogenic
fissures and paleopermafrost level. Under SEM they consist of tiny crystals, much smaller than in regular soft masses. Several
types of hard concretions were identified: rounded, irregular and platy. Small concretions in the modern Chernozem have similar
morphology and similar 14C-age as the rounded concretions of the upper paleosols. They are expected to represent the same generation of concretions.
Platy concretions fill the bottom part of the large fissures. The 14C-age of hard concretions varies from 3310±80 yrs. B.P in the 1st paleosol up to 20 400 yrs. B.P. in the 3rd. As a result we found the reflection of several wet-dry and cold-warm stages in carbonate morphologies and distributions.
High variability of carbonates at macro-, micro- and submicroscopic levels indicates several generations and multiphase formation
of carbonate pedofeatures in the loess-paleosol pedocomplex. Carbonate pedofeatures in the examined pedocomplex are more informative
for the study of late Pleistocene and Holocene climatic cycles rather than characterization of a single paleosol. |
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| Keywords: | Loess-paleosol pedocomplex pedogenic carbonates macr- and microforms |
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