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Трансформация локальных ледниковых депрессий по данным бурения и электротомографии, Борисоглебская возвышенность, центр Восточно-Европейской равнины
Late Pleistocene transformation of European glacial landscapes is often narrowed down to the impact of
postglacial linear erosion. Yet in the marginal zone of MIS 6 glaciation extensive watersheds were protractedly
affected by the postglacial flattening in periglacial and interglacial conditions. Local sediment sinks such
as kettle holes and dry valleys infilled throughout the postglacial stage can serve not only as records of
paleoenvironmental and paleoclimatic changes but also for assessing the scales of watershed denudation and
landscape transformation since the last glacial cover degradation. We attempted to use electrical resistivity
tomography for paleogeomorphological survey of a local flat-bottomed depression studied by conventional
lithological and stratigraphic approaches in a series of geological exposures and cores. The obtained series of
electrotomography profiles showed a contrasting picture of the relatively higher-resistive glacial base embedded
with low-resistive lenses 3–25 m thick atop. The latter were correlated with the postglacial loamy deposits
of colluvial and lacustrine origin that infilled the lows of initial glacial topography. It was revealed that the
depression has a particularly complex inner structure embodying at least two buried kettle holes divided by a
glacial ridge almost buried under the postglacial infill. They functioned as separate basins during much of the
Late Pleistocene and probably merged only at its final stages due to considerable sedimentary infill of the kettles.
Electrotomography cross-sections also showed a quite variable bottom relief of each kettle with significantly
steeper slopes than the modern sides of the depression. 8 geological and 4 electrotomography facies were
distinguished, with their correspondence to each other discussed and compared to the geophysical findings
of similar geomorphic objects in analogue regions of Central and Eastern Europe. Thus, electrical resistivity
tomography prospecting proved to be useful for detecting the postglacial loamy infills of initial lows of the glacial
topography and can be further employed to better understand the actual scales of the postglacial redeposition
and landscape modeling during the last 130 ka.