Morphological record of pedogenesis and landscape evolution in the upper quaternary pedosediments within the upper Volga river basin

Abstract

The morphological record of pedogenesis (mostly at a micromorphological scale) and the features of paleosols developed at the northern geographical extremity of the MIS3 paleopedoshpere (including the Bryansk fossil soils) are described. The profiles of the MIS3 paleosols (dark humic gley and peaty gley with the14С-age around 29-50 cal kyr BP) are located within the periglacial zone in the centre of the Russian Plain (56.7°-58.5° N) within the Upper Volga drainage basin. An assemblage of stable micromorphological features of paleosols studied includes the following: 1) ferruginous nodules and other pedofeatures, occasionally fragmented; 2) concentration (separation) of sand grains within certain microzones; 3) inclusions of raw organic matter, often deformed and oriented to different degrees within the matrix. Despite being buried for a long time period and superimposed by the Holocene pedogenetic processes (clay illuviation), the paleosols preserve some features of short-term (101-102 yr) and medium-term (102-103-4 yr) elementary pedogenetic processes (EPP). The short-term EPP include gleying, structure forming and cryogenic processes. The medium-term EPP include humus formation, peat formation and organic matter accumulation. A hypothesis of cryogenic formation of the paleosols studied is substantiated. Only an almost impermeable layer of permafrost could cause water-logging and gleying in these geological and geomorphological conditions.

Keywords

• bryansk paleosols
• mis3
• the russian plain
• periglacial
• micromorphological diagnostics
• pedosediments