Doklady Earth Sciences

Belyaev, Yu. R.; Panin, A. V.; Kiryuhina, A. D.; Koshurnikov, A. V.; Kramynin, A. M.; Pavlov, M. A.; Konstantinov, E. A.; Kurbanov, R. N.; Zakharov, A. L.; Sychev, N. V.

doi: 10.1134/s1028334x22700143pmid: N/A

A complex of works including geomorphological deciphering, field survey, drilling, electric prospecting, and dating of deposits using the radiocarbon method and optically stimulated luminescence are used for the interpretation of the Late Quaternary evolution of the western part of the Turan–Uyuk Basin. It is established that the total thickness of the deposits of the basin reaches 190 m. The Late Quaternary evolution of the basin includes the following main stages: (1) accumulation of alluvium and active lateral migrations of the Uyuk riverbed and simultaneous sedimentation of lacustrine sequences in the basin of the Belye lakes during most of the Late Pleistocene (at least, beginning from 77–87 ka) and the first part of the Holocene (prior to 6.1–6.2 ka); the formation of floodplain massifs of the 1st and 2nd generations; the internal delta of the Uyuk River, which dams the present-day Belye lakes, started to form no later than 25–16 ka; (2) the increase in freshet activity and activation of deep and lateral erosion between 6.1–6.2 and 2.4–2.6 ka; the formation of the 3rd generation floodplain; (3) the decrease in freshet activity and the size of the paleoriverbeds, the predominance of lateral migrations of the riverbed, and accumulation of alluvium in the last 2.4–2.6 ka; the formation of the 4th generation floodplain. The last stage is characterized by a shorter period of strong activation of cryogenesis. Permafrost began to form no earlier than 2.8 ka, and cryogenesis was mostly active at 1.35–1.10 ka. The Late Pleistocene stage of accumulation was preceded by a strong downcutting of the Uyuk valley, probably caused by the activation of tectonic movements. The chronological boundaries of this downcutting are determined only approximately: between 360–380 and 77–87 ka. The presence of a large dam lake, which occupied the central and western part of the basin and was suggested by some researchers, is not confirmed.

Konstantinov, E. A.; Karpukhina, N. V.; Zakharov, A. L.; Bricheva, S. S.; Ukraintsev, V. Yu.; Lazukova, L. I.; Rudinskaya, A. I.

doi: 10.1134/s1028334x22700258pmid: N/A

The paleohydrological settings in the Rostov lowland (Yaroslavl oblast) have been the subject of long-standing of disputes. The concepts for the Holocene fluctuations in the level of Nero Lake differ considerably among researchers. We have studied the structure of bottom sediments and bottom relief in the deepest, northeastern, part of the lake. A bathymetric survey was carried out. Drilling with the selection of undisturbed columns, GPR profiling, radiocarbon dating, and lithological analyses were conducted. Stratigraphic unconformities in the structure of the bottom sediments indicate a drop in the lake level in the Late Glacial and Early Holocene. The level dropped to 87 m asl, which is 7 m lower than the current water level in the lake. The size of the lake at this stage was reduced several times. The transgressive stage was established from 9 to 6.5 ka B.P.: the mean annual level of the lake could have risen up to 91–94 m asl, which is close to the modern level. In the interval from 6.5 to 2.4 ka B.P., a decrease in the level by 1–3 m below the current level is revealed. Then the level begins to grow gradually until it reached the current values 300–500 years ago. The main factor in the fluctuations in the level of Nero Lake in the Holocene is the change in the height of runoff threshold, caused by vertical deformations of the Ustye, Veksa, and Kotorosl river systems. These deformations were associated both with regional changes in fluvial activity and with the self-development of river channels.

Berkovich, K. M.; Zlotina, L. V.

doi: 10.1134/s1028334x22600335pmid: N/A

The transformation of a river bed under the influence of an alternating hydrological regime and sediment flux is considered with the example of the Ob River downstream from the Novosibirsk dam. The spatial and temporal manifestations of deep erosion over 60 years terminating in the relative stabilization of the riverbed and its relaxation have been revealed. They were manifested differently along the length of the river over 70 km. The regions where riverbed relaxation proceeded with different intensity have been distinguished. Additional mechanical riverbed disturbances played a significant role in the relaxation.

Vashkov, A. A.; Nosova, O. Yu.

doi: 10.1134/s1028334x22700155pmid: N/A

Three belts of marginal glacial deposits have been found in the southwestern part of the Kola Peninsula. They are consistent with three retreat phases of the Scandinavian Ice Sheet in the Late Pleistocene. Clast fabric analysis and lithological investigation of the glacial deposits and morphometric analysis of the glacial relief have made it possible to identify the imbricate–overthrust and folded glaciodislocations in the marginal ice complexes. Regularities in the arrangement of the marginal glacial deposits in the region have been defined by morphometric study of the present relief. The imbricate–overthrust glaciodislocations have been found in the structure of the first and second belts of the marginal glacial deposits. They correspond to single large ridges or massifs with parallel ridge landforms. Particular fragments occur as low ridges with glaciofolds in their cores composed of loose bedrock. The third belt of marginal glacial deposits consists of moraines of marginal folds and rare imbricate moraines interbedding with fluvioglacial deposits. In the present relief, this belt consists of ridge–hilly and hilly forms, and its characteristic feature is deltaic fluvioglacial deposits at the distal end of eskers. According to the clast fabric analysis and structural study of the glaciodislocations, the glacier was moving mainly along the White Sea basin eastwards during the generation phases of the first and second belts. At the time of formation of the third belt, the active glacier was advancing south and southeastwards. Each glacier retreat phase was accompanied by short-term oscillatory readvances. In the White Sea basin and on the moraine plain, glacier degradation was fast and areal in nature. Frontal deglaciation was characteristic for the convergence areas of the marginal glacial complexes. The new data on the structure of the glacial deposits, the structural study and clast fabric analysis of glaciodislocations implemented for the first time, and morphometric description of landforms have made it possible to reconstruct the dynamics of the last glacier cover in one of the key areas of the Kola region.

Lebedeva, E. V.; Zharkov, R. V.

doi: 10.1134/s1028334x22700131pmid: N/A

The formation of relief is accompanied by chemical and thermal effects within the stream valleys of geothermal zones, where manifestations of gas-hydrothermal activity are noted. It has been established that, in the valleys of the rivers considered, specific accumulative forms of micro- and mesorelief are formed both in the channels and on the slopes. The secondary treatment of alluvial deposits and bedrock by the hydrothermal solutions leads to a dramatic change in their properties and the features of fluvial processes. Activation of slope processes with the formation of landslide bodies and rockslide masses lead to the accumulation of slope material in the bottom, which is subsequently redeposited by mudflows. The forms of accumulative relief, which formed due to the gas-hydrothermal activity, were typified for the river valleys of four volcanic massifs on the Kuril Islands (Mendeleev volcano on Kunashir Island, Baranskii volcano on Iturup Island) and Kamchatka (Mutnovskii volcano and the Uzon-Geysernaya caldera). The main forms of accumulative micro- and mesorelief associated with various manifestations of gas-hydrothermal activity are distinguished; their characteristics are given, and the morphometric parameters are described. Typical processes in the valleys of geothermal zones involve not only the formation of various sinter forms and the cementation of floodplain and terrace deposits in places where mineralized thermal springs erupt, but also the formation of rather large landslide pseudo-terraces and the blocking of watercourses with dams composed of slope and mudflow material. Active weathering of bedrock and boulder–pebble material to clays can also be affected by acidic solutions. Often, sediments that compose floodplains and terraces morphologically look like typical pebble alluvium; however, they are actually a clay mass that is easily washed away by surface waters. With the attenuation of gas-hydrothermal activity, landslide bodies and sinter forms overgrow and morphologically look like ordinary river terraces.

Shvarev, S. V.

doi: 10.1134/s1028334x22700167pmid: N/A

The newest block-fault structure is revealed, and tectonic deformations exposed in coastal cliffs are studied and systematized as a result of morphotectonic studies on the territory of the Sambian (Kaliningrad) peninsula. The conjugation of multidirectional systems of morpholineaments is established in the morphostructure of the peninsula, defining the “block” tectonics of the peninsula with different roles in relief: (a) sublatitudinal and meridional systems predominate on the flanks, associated with the formation of the Gotland–Baltic graben system; (b) in the axial part of the peninsula, the NW system controlling the main Holocene uplift; (c) in the northeastern part, the NNW system determining the development of the Curonian Lagoon; and (d) in the southwestern part, the NE system setting the master plan of the Vistula depression. Deformations in loose sediments have been studied on the western and northern shores of the peninsula: (a) faults, including normal faults, reverse faults, and thrusts with an amplitude from centimeters to several meters; (b) folds, from micro-folds to gentle synclines with an amplitude of up to meters and a width of up to a few hundred of meters and compressed anticlines; (c) liquefaction, including deformation horizons, local homogenization, intralayer fragmentation, clastic dikes, associated with earthquakes of different strengths. Spatial and chronological relationships between sedimentation and deformations are established, indicating five stages of tectonic activation on the territory of the peninsula: (1) Saale (Moscow) late glacial (weakly active); (2) post-Saale (Moscovian) (maximally active); (3) late-Eemian–pre-Weichselian (Mikulinskii–pre-Valdai) (active); (4) late glacial–early Holocene (weakly active); and (5) late Holocene (weakly active). The most intense tectonic movements were at the post-Saalian (Moscovian) stage: the amplitudes of vertical fault displacements reached the a few tens of meters, and the thickness of the liquefaction horizons exceeded 1 m. At later stages, the intensity decreased, manifested in a decrease in the amplitudes of displacements to a few decimeters at the pre-Weichselian (pre-Valdai) stage and to the first centimeters in the Holocene.

Melekestsev, I. V.

doi: 10.1134/s1028334x22700179pmid: N/A

Olympus Mons (basement dimension is 550 × 600 km, absolute height is 21.1 km, relative elevation is 21.9 km, volume is 2.4 × 109 km3) is the largest volcanic edifice on Mars as well as on Earth. The Mars images of the regular combinations of features of volcanic and glacial forms on Olympus Mons have been interpreted and analyzed. The cardinal external similarity of these forms to the forms of large terrestrial tuyas of young volcanic regions was revealed. This, probably, testifies to their similar origin. The Olympus Escarpment, 3–6 km in height, bounds Olympus Mons at low latitudes (center is at 18° N, 113° E), which indicates that, during the formation of Olympus Mons, vast glaciers existed not only in the polar regions of Mars but far away from them. The distribution of extensive glacial moraines allowed us to evaluate the area of glaciation, equal to 1.5–2 × 106 km2, as well as the ice sheet thickness (about 3–6 km), comparable to the recent height of the Olympus Escarpment. Some distinct fragments of the glacial relief point to several phases of glaciations; the directions of the moraine lobe propagation record a clearly manifested asymmetry in the glacier distribution. In the SW, W, NW, N, and NE sectors of the Olympus Mons piedmont, the edge of the glacier was at a distance of 700–750 km from a crater; in the other zones, the glacier edge was at a distance of 500–600 km. Glacial and water-glacial formations, enriched in volcanic debris, are removed from the center of the volcano by colossal lahar-type mud-and-stone flows to the maximum (1100 km, Acheron Fossae) distance. These flows were formed as a result of the dramatical destruction of the walls of the glacial basin in which the Olympus tuya-volcano grew. A terrestrial analogue of a similar process is the catastrophic Jökulhlaup feature in Iceland, which is attributed to ice-filled calderas with volcanoes growing within them.

Ukraintsev, V. Yu.

doi: 10.1134/s1028334x2260030xpmid: N/A

Large paleochannels are considered to be a geomorphological phenomenon. The landscape–geomorphological traces of large paleochannels on the floodplains of the Volga River basin are reviewed, the regularities in their distribution are considered, and an improved method of analyzing the river floodplain topography based on remote sensing data is proposed. Based on analysis of high-resolution satellite images and digital elevation models of the Volga River valleys, more than 1700 sites with large paleochannels have been mapped. The morphology of the paleochannel makes it possible to reveal the landscape and climatic differences between the northern and southern parts of the basin. The distribution of large paleochannels in the Volga River basin is likely indicative of the fact that the duration and severity of paleoclimatic episodes of high river runoff on the East European Plain was maximum in the area occupied by recent steppes and forest–steppes. To the north and south of this area, there were fewer episodes of high runoff, and therefore, not too many geomorphological traces were left in the river valleys.

Mukhametshina, E. O.; Zelenin, E. A.; Pendea, I. F.

doi: 10.1134/s1028334x22700192pmid: N/A

Spore–pollen analysis of lacustrine and subaerial sediments of the KamPlen reference section in the Central Kamchatka Depression (CKD) is conducted. The results of the analysis allowed the reconstruction of the CKD landscape formation conditions in the Late Peni-Glacial, Late Glacial, and the transition to the Holocene, which significantly expands the paleogeographical record elaborated for the Holocene of Kamchatka into the past. It is established that, after 18 ka (under relatively cold climate), the watershed of the paleolake that filled the CKD during the last glaciation was characterized by open landscapes with dominant herbaceous–grass communities. The presence of pollen of trees and warm water plants indicates the limited scales of mountainous–valley glaciation. The identified cooling period of 15–13 ka characterized by scarcer vegetation did not lead to a significant expansion of glaciers. After 13 ka, warming of the climate with a gradual degradation of glaciers resulted in regeneration of coniferous forests on the paleolake watershed. The drainage of the lake at ~11.5 ka BP and the beginning of sedimentation of subaerial deposits in the area of the studied section approximately correspond to the lower boundary of the Holocene, which confirms the key role of the climate at stages of the CKD landscape formation during the period considered.

Chernov, A. V.

doi: 10.1134/s1028334x22700180pmid: N/A

The morphology of the floodplain–channel complex of the Moscow River and its development history before the beginning of intensive human intervention in its functioning are considered. The Moscow River valley reflects the lithological structure of the river basin in its various parts, as well as the relationship with the morphostructural plan of the upper and lower parts of the basin. According to the general morphology and floodplain–channel complex, the entire river valley can be divided into several morphologically homogeneous sections: Mozhaisk and Tuchkovo areas in the upper reaches, Zvenigorod–Moscow in the middle reaches, and an area with different widths of floodplains in the lower reaches. Each area is dominated by its own relief of floodplain–channel complexes: large macromeanders, the embedded nonfloodplain part, again macromeanders, and a set of different forms of floodplain relief in the alternating valley narrowing and widening in the lower area. The Late Glacial and Holocene history of the river was reconstructed based on the floodplain relief features in different parts of the valley and based on earlier studies. The radiocarbon dating of floodplain (oxbow) deposits recovered from different morphological sections of the floodplain–channel complexes of the river helped to reconstruct the natural development stages of the river valley during these periods: high water content and runoff coefficient in the Late Glacial, low water content in the early Holocene, floodplain rivers with many channels in the Late Holocene, and the current stage of active interaction of the natural and anthropogenic valley- and riverbed-forming processes. It is obvious that the first three stages ultimately served as a natural basis which over the past hundreds of years has been actively influenced by human activity. Meanwhile, traces of micromeanders found in the floodplain only in the lower reaches, marking a certain stage at the beginning of the sub-Atlantic period of the Holocene, have not yet been explained in the evolutionary series of the valley, floodplain, and riverbed of the Moscow River.