Boris V. Baranov

The article presents a general review and summary of investigations devoted to submarine landslides in the Okhotsk and Bering seas and Kurile–Kamchatka Trench. These works were carried out with the participation of the authors in several international projects. Analysis of bathymetric maps and seismic sections obtained during cruise SO201-1а of the R/V Sonne under the Russian–German KALMAR Project was carried out to reveal and delineate submarine landslides in the Emperor Seamounts Chain and on the Pacific floor to the southeast of the Kurile Island Arc. It was shown that submarine landslides are widespread in Northwest Pacific and occur in different environments, such as open continental slopes, slopes of seamounts and ridges and submarine canyons.

The timing and origin of Aleutian subduction initiation remain poorly constrained, yet they are central to understanding late Paleocene to early Eocene plate tectonic reorganization in the Pacific and its possible climatic consequences. Here, we use geochronologic and geochemical data obtained on western Aleutian arc samples from four basal submarine sequences, spanning ~700 km, to constrain Aleutian subduction initiation to ≥56 Ma. Early forearc lavas have similar compositions to forearc basalts erupted during the initial stages of Izu-Bonin-Mariana subduction in the western Pacific. Collision of the Olyutorsky Arc with Kamchatka-Koryak margin and subduction of the Izanagi-Pacific Ridge are likely to have triggered Aleutian subduction initiation and a change in absolute Pacific plate motion from WNW to N between 57 and 55 Ma, as shown with a GPlates model. Our study shows that Aleutian subduction initiation is a key event at the beginning of a major ~10 Myr plate reorganization in the circum-Pacific ending with Hawaii-Emperor-Bend formation. These tectono-magmatic events may have contributed to contemporaneous global climatic events in the late Paleocene and early Eocene.

High-resolution seismoacoustic data were obtained in the central Tatar Straight of the Sea of Japan in 59-th cruise of Research Vessel «Akademik M.A Lavrentiev» conducted as a part of the international «Sakhalin Slope Gas Hydrates» project in the summer of 2012. The data was used to identify types of reflecting signals echotypes, map their distribution fields, and determine sedimentation environments. These environments include sedimentation with weak or no bottom currents on the eastern side of the strait, underwater erosion and redeposition by bottom currents on its western flank; transportation and deposition of sediments by bottom currents and turbidite flows with the formation of conturite drifts and sedimentary waves in the central part of the strait. An assumption has been made about the direction and relative velocities of currents that influenced sediment accumulation on the western side of the strait and in its central part.

Three horizons, composed of mass transport deposits, were distinguished on seismic cross-sections in the upper sedimentary section of Laptev Sea continental margin. The mass transport deposits are formed in canyons and are transported into the Amundsen Basin on distance up to 325 km forming a wide continental rise. Earthquakes and huge gas emission from sediments are related to tectonic activity on the margin. They are triggers that cause collapse of canyon slopes with generation of landslide flows. The formation of a canyon system on the slope eastward from Gakkel Ridge could be caused by extension of the Eurasian Basin due to countermotion of the under-lithospheric current of the upper mantle convection sell beneath the Arctic region.

This article examines aspects of the application of geomorphometric methods to the identification of regional-scale lineaments using a digital relief model and a gravity field model in marine areas using the Laptev Sea as an example. The results of lineament analysis showed their applicability for further use in developing a model of earthquake source zones and seismic hazard assessment. The study showed the effectiveness of methods of shadow analysis and identification of keel forms by calculating the curvature of the relief for identifying large seismic lineaments, provided that the results of geomorphometric analysis are used together with data on the distribution of earthquake epicenters. The presented approach to identifying seismic lineaments can be very promising for the development of a lineament-domain-focal model of zones of possible earthquake sources in the vast shelf zones of Russia, for which there is no necessary volume of geological, geophysical and paleoseismological data.

The Arctic region, including vast shelf zones, has enormous resource and transport potential and is currently key to Russia’s strategic development. This region is promising and attractive for the intensification of global economic activity. When developing this region, it is very important to avoid emergency situations that could result in numerous negative environmental and socio-economic consequences. Therefore, when designing and constructing critical infrastructure facilities in the Arctic, it is necessary to conduct high-quality studies of potential geohazards. This paper reviews and summarizes the scattered information on the main geohazards in the Russian sector of the Arctic Ocean, such as earthquakes, underwater landslides, tsunamis, and focused fluid discharges (gas seeps), and discusses patterns of their spatial distribution and possible relationships with the geodynamic setting of the Arctic region. The study revealed that the main patterns of the mutual distribution of the main geohazards of the Russian sector of the Arctic seas are determined by both the modern geodynamic situation in the region and the history of the geodynamic evolution of the Arctic, namely the formation of the spreading axis and deep-sea basins of the Arctic Ocean. The high probability of the influence of seismotectonic activity on the state of subsea permafrost and massive methane release is emphasized. This review contributes toward better understanding and progress in the zoning of seismic and other geological hazards in the vast Arctic seas of Russia.

Contourite drift studies in six seas of Russia have been compiled and analyzed for the first time. The considered sedimentary bodies vary in size, age, and structure, are located at different depths, occur in various environments, and are attributed to several classification types. Our study combines these contourite drifts in two groups. The first includes shallow-water drifts on the shelves of Kara, Pechora, and Baltic seas; the second consists of deep-water drifts on the slopes and in the basins of the Sea of Japan, Sea of Okhotsk, and Caspian Sea. The relationship between the studied sedimentary bodies and bottom currents is considered.

This article discusses the results of a fluid inclusion studies in barite collected at the Jan Mayen vent field area (Troll Wall and Perle and Bruse) and Loki’s Castle vent field on the Mohns Ridge segment of the Arctic Mid-Ocean Ridge. Three mafic-hosted volcanogenic massive sulfide deposits were examined within the active vent fields that adequately correspond to the geological settings of ultraslow-spreading ridges and P–T conditions. Hydrothermal sediments were investigated to determine the temperature and salinity of the fluids responsible for barite precipitation. The hydrothermal origin of the barite was confirmed by its morphology. Fluid inclusions are two-phase and homogenize into the liquid phase on heating at temperatures below 287 °C. The salt concentration in fluids trapped in inclusions is 2.6–4.4 wt.% NaCl eq. The crystallization temperatures varied from 276 °C to 119 °C and from 307 °C to 223 °C for the Jan Mayen and Loki’s Castle vent fields, respectively. The data obtained allowed us to confirm evidence of fluid phase separation in the hydrothermal systems and to expand our knowledge of the temperature and salinity of mineral fluids previously known from recent direct measurements during the cruises within the G.O. Sars research vessel. The fluid inclusions data obtained from barites emphasize the fluid features characteristic of volcanogenic massive sulfide deposits, the similarities and differences among the studied hydrothermal sites and allow comparisons with similar products from other active hydrothermal systems.

Contourite drifts were for the first time detected on the SW Kara Sea shelf basing on аnalysis of bathymetry and seismoacoustic data obtained in RV “Akademik Nikolay Strakhov” cruises 41 (2019) and 49 (2020). The drifts are confined to narrow nearly NS-striking depression with depth reaching 240 m. They are separated from underlying sediments by basal unconformity, conditioned by origination of bottom current in marine environment after Barents-Kara shield melting during Late Plestocene – Holocene. Hydrological measurements performed during Cruise 89–1 of RV “Akademik Mstislav Keldysh” (2022) shows existence of bottom current with measured velocity up to 10 cm/s.

This article discusses the results of fluid inclusions study in barite collected at the Jan Mayen vent field area (Troll Wall and Perle & Bruce) and Loki’s Castle vent field of the Mohns Ridge segment of the Arctic Mid-Ocean Ridge. Three mafic-hosted volcanogenic massive sulfide deposits were examined within the active vent fields that adequately correspond to geological settings of ultraslow-spreading ridges and PT-conditions. Hydrothermal sediments were investigated to determine the temperature and salinity of the fluids responsible for barite precipitation. The hydrothermal origin of the barite was confirmed by its morphology. Fluid inclusions are two-phase and homogenized into the liquid phase on heating at temperatures below 287ºC. The salt concentration in fluids trapped in inclusions is 2.6–4.4 wt.% NaCl eq. The crystallization temperatures varied from 276ºС to 119ºС and from 307ºС to 223ºС for the Jan Mayen and Loki’s Castle vent fields, respectively. The data obtained allowed us to confirm evidence of fluid phase separation in the hydrothermal systems and to expand our knowledge of the temperature and salinity of mineral fluids previously known from recent direct measurements during the cruises within the G.O. Sars research vessel. The fluid inclusions data obtained from barites emphasize the fluid features characteristic of volcanogenic massive sulfide deposits, the similarities and differences for the studied hydrothermal sites, and allow comparisons with similar products from other active hydrothermal systems.