Layered Jurassic intrusions in Antarctica

The paper addresses the current understanding of the inner structure of the layered intrusions at Dufek Massif in the Pensacola Mountains and the Utpostane and Muren intrusions in Queen Maud Land, Antarctica, which are still poorly known to Russian geologists. The magmatic events at approximately 180 Ma, including the emplacement of layered intrusions, are thought to had predated the breakup of the Gondwana supercontinent. The spatiotemporal similarities of the intrusions determine the importance of the problem of whether they were produced by a single or more than one parental magmas, which are thought to have been derived under the effect of a superplume.     

Formation and Age of Brines in Solikamsk Depression

The chemical composition of the main types of brines in the area west of the Urals is studied. The brines involved are spatially and genetically associated with Permian halogen formations. The main role in the formation of chlorine–calcium brines, dominating the sedimentary cover in the basin, is shown to belong to the concentration convection of chlorine–magnesium salt-forming brine from the kungurskii evaporate paleo–water body into the underlying Paleozoic rocks and the subsequent metamorphization of the brine as a result of processes of metasomatic doomitization of carbonate rocks. Particular attention is paid to the condensation processes and the hydrogeochemical inversion in the subsurface hydrosphere of the region, which is associated with these processes. Estimates of the absolute age of brines based on the kinetic–geochemical technique are given.     

Multimodel Evaluation of Phytomass Dynamics of Tundra Plant Communities Based on Satellite Images

Izvestiya, Atmospheric and Oceanic Physics - This paper presents a two-stage method for solving the problem of predicting phytomass and the corresponding two-component model of phytomass dynamics....     

Spectral Analysis of Profile Topographic Data Using Modified F-Approximations

Izvestiya, Physics of the Solid Earth - Abstract—Analytical approximations are constructed and spectral analysis carried out for the profile data on terrain elevations obtained from global...     

Geodynamic evolution of the northern Molucca Sea area (Eastern Indonesia) constrained by 3-D gravity field inversion

In order to better understand the tectonic framework of the Northern Molucca Sea area, we inverted satellite and sea-surface gravity data into an iterative scheme including a priori seismological and geological data. The resulting 3-D density model images the various tectonic units from the surface down to 40 km. We proceed to various tests to assess the stability and robustness of our inversion. In particular, we performed an offset and average smoothing method to properly refine our results. The resulting model shows a striking vertical regularity of the structures through the different layers, whereas the density contrasts appear strongly uneven in the horizontal direction.The density model emphasizes the complexity of the upper lithospheric structure in the northern Molucca Sea, which is clearly dominated by the interaction between ophiolitic ridges, sedimentary wedges and rigid blocks of the Philippine Sea Plate. It also provides new, hard information that can be used in discussion of the evolution of the region.Large density variations are concentrated in the central part of northern Molucca Sea and dominate the upper lithospheric. North–south trending density structures along the Central Ridge and west dipping thrust faults on the western side of the region are clearly imaged. In the eastern part of the region, we distinguish several blocks, especially the Snellius Plateau which seems to be split into two parts. We interpret this as an oceanic plateau associated with thicker crust that previously belonged to the Philippine Sea Plate. This crust is now trapped between the Molucca Sea complex collision zone and the Philippine Trench, due to the development of a new subduction zone in its eastern side.     

The uranium content in Dictyonema shale of the Kaibolovo–Gostilitsy Area in the Baltic basin (Leningrad Region)

This paper reports the data on the uranium content in Dictyonema shale and phosphate rock in the Kaibolovo–Gostilitsy Area of the Baltic Basin (Leningrad Region). Specific features of the uranium ore in the studied area and stratigraphic rock sequence of the Early Ordovician Pakerort horizon are considered. A high uranium concentration in the Dictyonema shale layer has been determined, the correlation of uranium with other elements was defined, probable conditions of uranium ore genesis are described, and predicted uranium resources within the studied area are estimated.     

Peculiarities of the hydrological regime of the Ganges and Brahmaputra river mouth area

The basic peculiarities of the hydrological regime of one of the largest mouth areas of the world, i.e., the common mouth of the rivers of Ganges and Brahmaputra, are discussed. The main features of natural conditions (including climatic) of the mouth of these rivers and the delta drainage system are characterized. The hydrological regime of the Ganges and Brahmaputra rivers, the largest rivers of South Asia, is studied in greater detail; the quantitative assessments of the water and sediment runoff of these rivers are specified. Provision is made for revealing the basic peculiarities of river flow distribution among numerous delta branches, annual floods during southwest monsoons, tidal phenomena in the maritime zone of the delta, and disastrous storm surges and inundations in the period of tropical cyclones. Flood control measures taken in Bangladesh to protect the population and lands are described.     

Sequence of Early Precambrian metamorphic events in the southern Prince Charles Mts., Eastern Antarctica

The results of geological study of the mountain framework of the southern part of the Lambert Glacier, Mawson Escarpment, Eastern Antarctica, are discussed. The studied territory is of key importance for understanding the regional geological history. The Ruker and the Lambert rock complexes have been distinguished at the Mawson Escarpment. The former is subdivided into the Mawson and Menzies groups. The polymetamorphic rocks of the Mawson Group comprise granite gneiss, orthopyroxene gneiss, and crystalline schists dated at >3000 Ma combined with tectonic wedges and blocks of the variegated sequence with ultramafic (komatiitic) rocks. The find of those rocks allows us to suggest that an ancient granite-greenstone domain existed in the territory of the Prince Charles Mts.; this domain is retained only as tectonic wedges amongst granite gneisses of the Mawson and Menzies groups composed of polymetamorphic terrigenous rocks with basic sills. The following sequence of metamorphic mineral assemblages in the Menzies Group has been established: (1) And-Crd ± St, (2) Ky-St-Grt-Bt-Ms, (3) Sil-Grt-Crd. The andalusite-type metamorphism of rocks pertaining to the Menzies Group probably has the same age as greenschist metamorphism of rocks belonging to the Collaboration Group (2917 ± 82–2878 ± 65 Ma at Mt. Ruker). The formation of kyanite-staurolite mineral assemblage (mounts Stinear, Maguire, Rymill; South Mawson Escarpment) might be related to a metamorphic event dated at 2400–2350 Ma. The formation of sillimanite-garnet and sillimanite-cordierite assemblages with staurolite relics correlates in time with emplacement of the MacColly granite 600–500 Ma ago. Polymetamorphic rocks of the Lambert Complex are migmatites and gneisses, often with orthopyroxene relics. Blocks of ultramafic rocks are localized amongst granite gneisses. The superimposed metamorphism of amphibolite and granulite facies took place 1800 Ma ago. The model Nd age of ultramafic rocks (2500 Ma) is treated as the time of emplacement of magma into the rocks of the Lambert Complex. Isotopic and geochemical evidence for Early Paleozoic granulite-facies metamorphism is known.     

Hydrological and morphological processes at river mouths of the Caspian Sea Region as possible analogs of expected changes of mouths of other rivers in Russia and the world

Present changes in the regime and structure of mouths of rivers, which empty into the Caspian Sea, are discussed. The similarities and differences of these processes at the mouths of different rivers of the Caspian Region were revealed. Assessment was made of the impact of changes in river water runoff and sediment load and in the Caspian Sea level as well as the nearshore zone relief and local hydraulic engineering activities on the processes under study. Anomalous features of the processes occurring at the mouths of the Volga and Terek rivers were revealed and explained. Hydrological and morphological processes typical of the present mouths of the rivers of Ural, Sulak, and Kura were revealed; these processes could be accepted as universal and possible analogs in assessing the expected changes at the mouths of other rivers in Russia and the world in the XXI century.