Seismogenic Structures in Sediments of Different Lithological Composition and Their Position in Mesozoic–Cenozoic Sections of the Northern Caucasus

Abstract—

A comparative analysis of the morphological features of horizons affected by paleoearthquakes revealed significant difference of seismites from lithologically different deposits. Powerful earthquakes determine not only the destruction of the sedimentary structure of near-surface deposits and their chaotic mixing, but also actively affect the underlying layers to a depth of several tens of meters; since the degree of diagenetic lithification of rocks in different horizons varies with depth, the nature of their seismogenic transformations also changes. It was found that major seismic events were associated with the time intervals of tectonic and paleogeographic restructuring of sedimentation basins, which consisted in the intensification of the basin floor subsidence and changes in the composition of sediments accumulated in the paleobasin. A special type of seismites was formed during the impact of earthquakes on siliceous deposits, which have been spanned by the diagenetic redistribution of authigenic mineral matter in a gel state.