Ore Genesis Laws in Subduction Zones

This paper considers and validates questions related to the multistage enrichment of the Earth’s crust in ore elements in subduction zones. We discuss some physical and chemical parameters of metamorphism and hydrothermal transformation of structural material complexes in these areas. The spatiotemporal patterns of ore genesis are demonstrated with the example of metallogeny of the Ural and Verkhoyansk–Kolyma fold belts.     

Evolution of magmatic and hydrothermal activity in the western Arctic and North Atlantic regions

This paper discusses the geodynamic evolution of the lithosphere in the Arctic region during the Phaneorozic and its polyphase lithotectonic reorganization. Spatiotemporal patterns of the mosaic junction of lithospheric plates of different age are presented for the Caledonian–Hercynian stage and for the Cenozoic evolution of the North Atlantic and Arctic oceanic basins. Special attention is given to the intersections of fault systems with different kinematics, which control the manifestation of peculiar magmatism and the formation of numerous mineral deposits. It is shown that the hydrothermal activity of the region is related to the ocean opening in the Eocene and is confined to the mid-ocean ridge.     

New data on mantle seismicity of the Caspian region and their geological interpretation

The results of detailed seismological observations with bottom recording systems carried out in 2004 and 2006 near the Dagestan coast of the Middle Caspian are considered. The records of more than 550 micro- and weak earthquakes with M_L = 0.1–4.7 (M_LH = ?0.7 to 4.3) were obtained during 165 days of recording; a fifth of these earthquakes occurred in the upper mantle at a depth of 50–200 km. Over the entire period of instrumental recording since the 1930s, only 10 mantle earthquakes with M_LH = 3.5?6.3 have been recorded by on-land systems. The highest density of earthquake epicenters with source depths down to 50 km is established on the Middle Caspian coast between Derbent and Izberbash and in the adjacent water area. The mantle earthquakes with hypocenters at a depth of 60–80 km cluster beneath the western wall of the Derbent Basin, whereas deeper hypocenters are located beneath both the wall of this basin and the Middle Caspian coast. The sporadic mantle earthquakes recorded in 2004 (about 30 shocks), determined by a network of systems with a small aperture, depicted a zone plunging beneath the Greater Caucasus with indications of a peculiar “subduction” of the Scythian Plate beneath the Caucasus. Subsequent observations based on a more extensive network were carried out in 2006. They substantially changed the pattern of mantle earthquake hypocenters. According to this evidence, the sources of mantle earthquakes make up a dispersed cloud extended in the vertical direction beneath the Middle Caspian coast and water area, which may be regarded as a relic of tectonic activity of a bygone tectonic epoch. A comprehensive tectonic interpretation of the detected seismological phenomenon is given.     

Modeling of the annual and spectral evolution of hydrooptical characteristics using a model for shelf ecosystem and remote observations

Mathematical modeling of the ecosystem in the northwestern shelf of the Caspian Sea is based on the method of aggregation and averaging with the subsequent hierarchic decomposition. This approach includes a step-by-step comparison of the modeling results with the data of observations. A block of optical characteristics (absorption coefficient, backscattering coefficient, and coefficient of diffuse light reflection) built into the model made it possible to use the data of simultaneous contact and remote observations. The observations were performed during the expedition of R/V Tantal (2004–2005) together with the data of the SeaWiFS satellite ocean color scanner. A comparison of the results of the modeling and the data of observations demonstrated their qualitative and quantitative agreement, especially in the case of the coefficient of diffuse light reflection.     

A geodynamic model of the evolution of the Arctic basin and adjacent territories in the Mesozoic and Cenozoic and the outer limit of the Russian Continental Shelf

The tectonic evolution of the Arctic Region in the Mesozoic and Cenozoic is considered with allowance for the Paleozoic stage of evolution of the ancient Arctida continent. A new geodynamic model of the evolution of the Arctic is based on the idea of the development of upper mantle convection beneath the continent caused by subduction of the Pacific lithosphere under the Eurasian and North American lithospheric plates. The structure of the Amerasia and Eurasia basins of the Arctic is shown to have formed progressively due to destruction of the ancient Arctida continent, a retained fragment of which comprises the structural units of the central segment of the Arctic Ocean, including the Lomonosov Ridge, the Alpha-Mendeleev Rise, and the Podvodnikov and Makarov basins. The proposed model is considered to be a scientific substantiation of the updated Russian territorial claim to the UN Commission on the determination of the Limits of the Continental Shelf in the Arctic Region.     

The forearc extension in the Central Kuril Islands and the trench rollback

On the basis of bathymetric and seismic data, obtained during cruises 37 (2005) and 41 (2006) of R/V Akademik M.A. Lavrentiev, a new structural scheme of transverse faults in the forearc of the Central Kuril Islands was compiled, the fault kinematics was studied, and a model of the extension zone in the structural pattern of the study area was proposed. According to this model, the trench rollback and development of back-arc basins resulted from the continuous supply of material into the upper mantle convection cell owing to subduction and an increase in the dynamic pressure that pushes the subducting plate, causing it to migrate toward the ocean.     

Prospects for Synthesizing Ecological Risk Models and Big Data Technologies for Marine Ecosystems

Izvestiya, Physics of the Solid Earth - Abstract—A possible approach combining ecological risk models, on the one hand, and Big Data theory and practice, on the other hand, is proposed. The...     

Contourite Drifts in the Tartar Strait,Sea of Japan

Doklady Earth Sciences - Contourite drifts were first detected in the Tatar Strait in the framework of the Sakhalin Slope Gas Hydrates International Project (2012–2015). The number of...     

Structure of the Khatanga–Lomonosov Fracture Zone according to Seismic Data

Doklady Earth Sciences - Based on the results of geophysical data interpretation, the structural features of the Khatanga–Lomonosov fracture zone (KhLZ), adapted to the junction zone between...     

Two-Element Keyboard Model of Generation of the Strongest Subduction Earthquakes

Doklady Earth Sciences - A model for the generation of the strongest earthquakes in subduction regions under conditions of the block structure of the medium is considered. This model represents a...