New data on potential fields are presented, compared with previous ideas about the regional structure and rift genesis of the Yenisei-Khatanga regional depression basement. Our 2D modeling based on geophysical data confirms the results of previous works regarding the identification of two types of the basement, and is consistent with the gravity-geodynamic concept of the formation of the Yenisei-Khatanga regional trough and the tectonic structures that complicate it, such as the Rassokhinsky and Balakhna megaridges. Also, as a result of our study of potential fields, the presence of a large volume of magmatic masses of ultrabasic and basic composition in the axial part of the Yenisei-Khatanga regional trough, Permian-Triassic age, was established, which confirms the rift mode of the region's development.

Peculiarities of the formation of marginal plateaus in the early period of the opening of the North Atlantic Ocean are considered. The oceanic opening between Greenland and Europe (formation of the North Atlantic Ocean) began approx. 50–55 Mya after a long period of rifting, followed by the formation of the Aegir spreading ridge and the formation of the basin of the Norwegian Deep. Since that moment, the formation of a series of specific structures (marginal plateaus) began. The article considers conditions for their formation, using the physical modeling method. Three groups of structures were distinguished and typified according to the formation mechanism. A series of experiments was performed to each type of structures. Experimental results are compared with our proposed model for the formation and evolution of marginal plateaux.

The results of our research conducted at the junction of geology, speleology and archeology are presented. Every cave is considered as an integral part of the enclosing geological system. Representative examples show the nature of the interrelationships of caves with structures of the continental crust of Eurasia, Africa and North America. The research was performed within the framework of the pulsationally expanding Earth model. According to this model, at the Pleistocene–Holocene turn, our planet was bombarded by a stream of asteroids, after which it switched to a pulsed compression mode, with a sharp activation of orogeny at the Holocene beginning. At that time, caves with their Paleolithic–Neolithic cultural layers were deformed. Their deformations are considered as Holocene activation indicators.

The considered part of the Mid-Atlantic Ridge extends from the Agulhas-Falkland fracture zone to the Bouvet triple junction. This segment has a contrasting topography. In its southern part, it has the morphology of an axial rise, while in its middle part it has the morphology typical for a slow-spreading rift valley. In the northern part, an area with transitional morphology can be distinguished. Three morphostructural complexes of transverse faults are distinguished, approximately corresponding to areas with various morphology. Such a different structure and segmentation of the spreading ridge became possible owing to the thermal influence of the Shona and Bouvet mantle plumes in the southern part of the considered segment and the Discovery mantle plume in its northern part. To reconstruct the morphostructure formation conditions in the ridge axial zone, physical modeling was implemented. In our experiments, we obtained various relief types and transverse discontinuities complexes depending on the distance from the thermal anomaly. They match the natural morphostructures. The modeling results suppose that the main formation conditions of the contemporary Mid-Atlantic Ridge terrain are spreading obliquity, thermal anomaly intensity, and the plume center position relatively to the spreading axis.

This article continues the series of publications on the indicators of Holocene activation. Using the examples of the Volga and Amur rivers with their tributaries and the Razdolnaya River, the interaction of the river network with the Holocene orogenic system of the Alpine–Himalayan and Pacific mobile belts of Eurasia was studied. The river network is conformal to their orogenic system. Examples of the control of river valleys by shear systems of active faults are given. The influence of the rivers on the formation of erosional relief was studied. It is shown that loose sediments of the Mesozoic-Cenozoic rifts thrown up in the Holocene are actively destroyed by the river network, with a shear of up to many hundreds of meters. The rises on the riftogen framing and their internal rises, composed of strong pre-Mesozoic rocks, are weakly eroded. Many of them have a contrasting, nonequilibrium relief. The study was conducted within the framework of the pulsatingly expanding Earth model developed by the author.

The thermal evolution of the permafrost in the sedimentary section of the Tyumen superdeep SG-6 well has been numerically reconstructed using the ICE2020 software package, which is part of the GALO flat basin modeling system. The thermal evolution of the sedimentary strata in the last 3.5 My is considered as the final stage of the basin modeling, whose formation began with continental rifting in the Late Permian. Abrupt climate changes in the late Pliocene–Holocene led to a decrease in the rock temperature by 15–20°C in the upper 1–1.5 km of the SG-6 sedimentary section. The maximum thickness of the permafrost in the study area was about 711 m, reached 2.6 Mya. The maximum thickness of the permafrost for the last ice age (23–18 thous and years ago) was 412 m, reached about 14.5 thousand years ago. According to our modeling, the modern base of the permafrost is at the depth of 311 m and is degrading with the rate about 13 m/1000 y. The results of our calculations with a database of climatic data limited to the last 50 and 100 thousand years differ markedly from the modeling results with the complete database for the last 3.5 My.

A scheme of formation of the sedimentary blanket of the South Kara basin is considered, which can further be used for numerical reconstruction of its thermal history. The scheme is based on our analysis of the literature information on the structure and geological history of the Barents-Kara region. This information included an interpreted seismic profile crossing the studied area, drilling data from four wells located along the profile (the University, Rusanov, Leningrad and Kharasavey ones), measurements of the heat flow and deep temperatures in the basin. The proposed scheme considers the formation of the basin as a series of sedimentation stages with various combinations of clay shales, siltstones and sandstones and sedimentation in the Cretaceous and Paleogene with their subsequent erosion in the Miocene. The erosion amplitude is estimated by the observed change in the porosity of sedimentary rocks with depth. The initial heat flow in such a model should correspond to the flow of modern axial zones of continental rifting or be lower for the areas remote from the corresponding segments of the Late Permian-Early Triassic continental rifting system.