Rare-metal granitoids of the Ulug-Tanzek deposit (Eastern Tyva): Age and tectonic setting

Doklady Earth Sciences -     

Middle Paleozoic basic magmatism of the northwestern Vilyui Rift: Composition, sources, and geodynamics

Middle Paleozoic magmatism at the eastern Siberian platform was related to riftogenic processes, which were most clearly expressed in the Vilyui Rift and led to the formation of rift depressions filled with sedimentary-volcanogenic rocks and extended basaltic dike belts in rift shoulders. Two fields of diamondiferous kimberlites were found along with basaltic dikes in the Vilyui-Markha dike belt surrounding rift in the northwest. Active subalkali basaltic magmatism predated the emplacement of kimberlite bodies, which occasionally (Nyurba pipe) are cut by dikes of potassium alkali basalts. Based on geochemical and Sr-Nd isotopic characteristics, deep-seated sources were determined for the intrusive and volcanic basalts of the northwestern shoulder of the Vilyui rift. The REE distribution patterns of the studied rocks normalized to the primitive mantle are close to that of OIB, except for somewhat higher HREE. In the diagrams of indicator ratios of trace and rare-earth elements, the basalts are also plotted in the OIB field, being located between the end member of plume composition (FOZO) and enriched mantle sources. The rocks have positive ε_Sr (+3.5 and +28.6) and ε_Nd (+1.3 and +5.3). In a diagram ε_Nd(T)-ε_Sr(T), two fields with distinct content of radiogenic Sr are distinguished, which can be regarded as derived by mixing of the moderately depleted PREMA-type mantle and a source enriched in radiogenic Sr. Available isotope-geochemical data confirm that OIB type basalts of the region were generated by plume activity. The geodynamic setting of Middle Paleozoic magmatism and rifting in the eastern part of the Siberian platform is considered in light of plume-lithosphere interaction. The sequence of tectonomagmatic events during evolution of the Vilyui rift is consistent with the model of plume-lithosphere interaction or the model of active rifting.     

Evolution of the Barents Sea basin and oil and gas potential of coastal zones in the Kola region

The perspectives of development of the Varanger–Timan petroleum basin are considered. The Varanger–Timan oil-and-gas basin was formed in the Riphean and Vendian on the passive continental margin of the East European Plate. Evolution of the Barents–Kara region in the Mesoproterozoic and Neoproterozoic led to a mosaic junction of the lithospheric plates having different ages and having undergone significant alterations during the Caledonian and Variscan orogenies. The spatiotemporal regularities of the interaction between geodynamic processes and conditions providing for the formation of conventional and unconventional hydrocarbon fields are described.     

Results from field and stationary tests of the seismic signal recorder Delta 03

The operation of a new domestic seismic signal recorder Delta 03 is analyzed. The optimization of technical requirements on parameters of the recorder, the test cycle, adjustment in the process of testing individual technical solutions, and improvement of the device were carried out in close cooperation with its designers from OOO Logic Systems (Ramenskoye, Moscow Region). At the time of writing, the recorder Delta 03 is a robust device that is recommended for use in seismic monitoring systems of various levels.     

The Age and Composition of Alkaline Rocks of the Dugda Massif (Eastern Sayan): Patterns of the Manifestation of the Late Paleozoic Rare-Metal Magmatism in the Southwestern Fold Frame of the Siberian Platform

Doklady Earth Sciences - The age and geochemical characteristics of alkaline rocks of the Dugda massif (Eastern Tuva), attributed to the East Sayan Late Paleozoic rare-metal magmatic zone, have...     

Active neutron sensing of the Martian surface with the DAN experiment onboard the NASA “Curiosity” Mars rover: Two types of soil with different water content in the gale crater

This paper presents the water and chlorine content estimates on the bottom of the Martian crater Gale obtained by processing the data of active neutron sensing with the DAN experiment onboard theNASA “Curiosity”Mars rover at 412 spots along the 11-kilometer track. For 78% of the examined spots the water distribution in depth is found to be homogeneous with a mean content of 2.1±0.5% by mass (here and elsewhere variations correspond to the mean square deviations). For 22% of the examined spots the data require a two-layer model of water distribution down to the sensitivity limit of about 60 сm. The mean water content in upper layer of these spots is about 2?3% by mass, which is close to the content for spots with the homogeneous water distribution. In 8% of the examined spots the water content in the bottom layer at a depth of 27 ± 18 сm increases to 5.6 ± 2.7%. In 14% of the examined spots the water content in the bottom layer at a depth of 14 ± 7 сm decreases to 1.2 ± 0.5%. For interpretation of these results we conclude that the Gale crater has areas both with high and low water content, which correspond to distinct sedimentary layers from different past epochs, when sedimentation process took place underwater and in air correspondingly.     

Geochemical classification by means of mapping resultants

The paper presents a new method for visualizing multidimensional numeric fields. The method consists in a special way of projecting analytical tests from the multidimensional space of attributes onto a single chart plane. The suggested technique proved to be efficient in interpreting geochemical data.     

On the Study of Spatial Variability of the Composition of the Substance of Mars in Experiments on Gamma-Ray Spectroscopy on Board the Mobile Vehicle using the Method of “Tagged Charged Particles”

Solar System Research - Methods are discussed for studying the variability in space of the substance composition of the surface of Mars in experiments on gamma-ray spectroscopy on board a mobile...