Provenance change in the Irkutsk coal basin during the early and middle Jurassic: Geochemical and Sm-Nd isotope evidence

On the basis of the recently accepted chronostratigraphic chart, Jurassic sedimentation in the Irkutsk coal basin took place over a short time interval (~23 My), from the Pliensbachian (~191 Ma) to the Aalenian (~170 Ma). In this study, we present geochemical and Sm-Nd isotope data for sedimentary rocks of the Prisayan and Kuda formations and those in the upper course of the Angara River, which were deposited over an even shorter time interval (from ~174 to 170 Ma), as indicated by new data on biostratigraphy. Our results suggest that a greater contribution from Transbaikalia compared to that from the Siberian Platform during sediment deposition in the Irkutsk coal basin may reflect the onset of mountain building in Transbaikalia and reorganization of the river drainage network during the Middle Jurassic.     

Biogeographic Zoning of Russia’s Far Eastern Seas and Adjacent Waters Based on Nekton Trawling Samples

The article presents the results of biogeographic zoning of the epi- and mesopelagic region based on nekton areas using a new modification of the Shorygin method. It is shown that the position and boundaries of biogeographic areas are related to real relatively stable elements of the biotope (water masses, currents, frontal zones, eddies, and rings). A pronounced latitudinal pattern of the areas of natural zones is not always seen. Zoning becomes less detailed from the top layer of the epipelagic to mesopelagic region, and the zonalities of mesopelagic and epipelagic areas are not similar. We propose a new zoning approach to solve dynamic biogeography problems.     

Oil seeps in the southeastern Black Sea studied using satellite synthetic aperture radar images

One of the tasks being completed while oil pollution monitoring in the Black Sea, was a study of natural seepage. Two known oil seeps are located in the southeastern section, the Georgian sector, from which crude oil enters the marine environment. The archives of European Space Agency and ScanEx Research and Development Center have a considerable quantity of synthetic aperture radar (SAR) images acquired in 1993–2011 by the ERS-1/2, Envisat, and Radarsat-1 satellites, on which seep oil slicks are clearly visible in this region. Processing of the collected SAR images with detected slicks in combination with the geoinformation approach has revealed a link of these slicks with the bottom sources on the local sedimentary structure in the Southeast Black Sea; their analysis provides both new insight into this phenomenon and new information to help understand nature of these oil seeps. On the basis of an analysis of collected SAR images and detailed bathymetric data, information on the source positions on the bottom and estimates of oil volumes entering the sea surface are obtained.     

Hydrophysical and morpholithodynamic processes in the Onega River’s estuary

New data on the Onega River estuary’s hydrological and morpholithodynamic regimes are presented. The river’s bottom structure and soil lithology are described on the basis of field sonar survey materials. Proceeding from the analysis of the hydrographic maps, the dynamics of the Onega River’s mouth bar is tracked over the period of 1830–2000.     

Estimates of the maximum land-fast ice thickness probable once in 5, 10, 25, 50, and 100 years

Presented are the empirical, nonparametric (quantile), parametric, and randomized estimates of the maximum land-fast ice thickness in the Northern Caspian probable once in 5, 10, 25, 50, and 100 years. The annual maxima of the land-fast ice thickness for the 72-year period from 1937 to 2008 are computed using the one-dimensional thermodynamic model of the sea ice developed at Arctic and Antarctic Research Institute.     

Connection of the interannual variations of the arctic and antarctic oscillations with eddy and wave activity characteristics

One of the problems in an investigation of the Arctic and Antarctic oscillations is the lack of a clear definition of a mechanism driving the oscillations. The primary cause is most often considered to be a positive feedback between zonal velocity and transfer of angular momentum by eddy and/or wave disturbances. Comparison of the variations of the oscillation indices and characteristics of eddy (wave) activity gives no strong evidence of this hypothesis. The anomalies of the calculated correlation curves are less significant and less regular than those of the correlations between oscillation indices and average zonal characteristics of the meteorological fields. The difference in the spatial structure of wave activity and zonal velocity anomalies is most pronounced in the Southern Hemisphere. Probably, most of the wave and eddy disturbances linked to the oscillations are not the cause but the effect of these oscillations, for example, in the interaction of varying zonal flows with mountain masses.     

Detrital Monazite from Upper Jurassic Sediments in the Central Part of the Frolov Megadepression,Western Siberia: Chemical Dating and Provenances

Lithology and Mineral Resources - Detrital monazite from Upper Jurassic sediments in the central part of the Frolov megadepression, West Siberian megabasin, is studied. Chemical composition of the...     

Paleogeography of the Bazhenov Formation of Western Siberia According to the Distribution of Rare Earth Elements

Doklady Earth Sciences - The Bazhenov Formation is represented by Late Jurassic black shales. Russia is the first in the world by the reserves of shale oil, which is mostly related to the Bazhenov...     

Albian–Cenomanian Granitoid Magmatism and Copper Ore Genesis in Sikhote-Alin (Far East,Russia)

Doklady Earth Sciences - The Late Albian–Early Cenomanian epoch of Au-Cu porphyry ore mineralization has been distinguished within the Sikhote-Alin. The development of ore mineralization is...     

New Data on the Age of Neoproterozoic Volcanic Rocks of the Isakovka Terrane,Sayan–Yenisei Accretion Belt (U–Pb,Zircon)

Doklady Earth Sciences - A Late Neoproterozoic U–Pb zircon age is established for the first time for arc metadacites (691 ± 8.8 Ma) and basalts (572 ± 6.5 Ma) from the...