Ground Disturbances in Different-Age Sediments of the Klinsko-Dmitrov Ridge

Abstract: In this paper we study paleocryogenic formations and lithogenic dislocations that arose both during and after the formation of deposits in the Dmitrov quarry, Moscow oblast (56°19′07″ N, 37°33′16″ E). In the top of the lacustrine–swamp complex of Mikulinsko–Early Valdai age, subaerial initially ground veins filled with mantle loams, which formed into the cold final stage of the Early Valdai (MIS 4), while in its lower layer, subaqueous pseudomorphs over polygonal-vein ice as drapping structures were identified. At the boundary of deposits of the Moscow and Mikulin age, ground veins with a vertical orientation of coarse clastic host layers, which, in our opinion, may have a convective nature, are described. In the middle part of the section of the marginal zone of the Mikulin complex, in sandy–silty sediments displaced along the consedimentary fault with clay interlayers, pseudoseismogenic diagenetic disturbances in the form of convolute folds at the sand/clay boundary and sand pseudonodules in peaty sand and sand in silt, were found. These structures could be the result of the development of gravitational instability in sediments of contrasting density, which is consistent with the lower dispersion and higher density of sediments in the upper layer of convolutions or inside pseudonodules. The results make it possible to significantly refine the conditions for the formation of soil disturbances in Quaternary deposits of tectonically stable periglacial regions.