Numerical modeling of salt tectogenesis in the Cambrian deposits of the cis-Yenisei sedimentary basin (PR3-PZ) (West Siberia)

Density sections of the Upper Proterozoic-Paleozoic cis-Yenisei sedimentary basin were numerically modeled to show that the gravity mechanism was sufficient to bring about linear deformation structures. The main conditions of their formation and development have been determined. Comparative analysis of the results of modeling with variations in initial parameters shows an important role of dolomite interbeds in the formation of structures in the section of Cambrian evaporates. The specific evolution of the structures was related to the specific basin sedimentation and the subsequent tectonic evolution of the region as a whole. The conclusion has been drawn that the tectonic influence of neighboring folded zones might have triggered salt tectogenesis.     

Petroleum surface oil seeps from a Palaeoproterozoic petrified giant oilfield

Early Palaeoproterozoic rocks from the Onega Basin in Russian Fennoscandia contain evidence for substantial accumulation and preservation of organic matter (up to 75 wt% total organic carbon) with an estimated original petroleum potential comparable to a modern supergiant oilfield. The basin contains a uniquely preserved petrified oilfield including evidence of oil traps and oil migration pathways. Here, we report the discovery of the surface expression of a migration pathway, along which petroleum was flowing from the sub-surface. This surface oil seep, the first occurrence ever reported from the Palaeoproterozoic, appears as original bitumen clasts redeposited in Palaeoproterozoic lacustrine turbidites. The δ¹³C_org of clastic pyrobitumen ranges between −35.4 and −36.0‰ ( n  = 14), which is within the range of interbed- and vein-trapped fossil oil (−46 and −24‰), suggesting similar source. Biogenic organic matter, whose isotopic composition was modified during thermal maturation, is the likely source for the migrated hydrocarbon.     

“False” Sigmoids in the Solar Corona

Astronomy Reports - As a rule, sigmoidal structures in the colar corona, i.e., structures having the appearance of an S or reversed S, are taken to be evidence for twisting of the magnetic-field...     

The fauna of the Aral Sea in 1989. 1. The benthos

The benthos of the Small and Large Aral Sea was investigated in 1989. OnlyNereis diversicolor, Syndosmya segmentum, Cerastoderma isthmicum, Caspiohydrobia spp., Chironomidae andPalaemon elegans occurred in the Small Sea. In the Large Sea, the benthos was similar, but Chironomidae were absent andRhithropanopeus harrisii was present.     

Motion of an eruptive prominence in the solar corona

A model for the nonradial motion of an eruptive prominence in the solar corona is proposed. Such motions, which can sometimes be inaccessible to observation, result in an apparent break in the causal link between eruptive prominences and coronal mass ejections. The global magnetic field of the Sun governs coronal plasma motions. The complex structure of this field can form prominence trajectories that differ considerably from a simple vertical rise (i.e., radial motion). A solar filament is modeled as a current-carrying ring or twisted toroidal magnetic rope in equilibrium with the coronal magnetic field. The global field is described using two spherical harmonics. A catastrophic violation of the filament equilibrium followed by its rapid acceleration—eruption—is possible in this nonlinear system. The numerical solution of the equations of motion corresponds well to the eruption pattern observed on December 14, 1997.     

Multipath mitigation by conventional antennas with ground planes and passive vertical structures

An antenna ground plane (GP) plays a major role in the mitigation of multipath coming from underneath the antenna. A distinct trend in user antenna size and weight reduction has been observed during recent years. With this focus in mind, an overview of conventional flat conductive and impedance GP is provided. Results of modern developments of passive vertically stacked structures are discussed. The possibility of obtaining a reasonable level of multipath mitigation with vertical structures of several centimeters is shown.     

The Influence of the Ufimian Tectonic Concentric Structure on the Hydrocarbon Migration and Ore Genesis

The Ufimian tectonic concentric structure (UTC) is a regional structure with concentric and zonal structure of the internal gravity field. In the Neoproterozoic this structure was at higher hypsometric level relative to the Bashkir Meganticlinorium. The most significant uplift of this tectonic concentric structure happened at the beginning of the Karatau time (~825 Ma) and was accompanied by the formation of a ring fractured zone, favorable for hydrocarbon migration from the Lower Riphean black shales. Due to this, bitumens with higher Mo content in the Neoproterozoic and Paleozoic deposits are confined spatially to this zone. The bitumenosity of the Neoproterozoic deposits on the southern slope of the Ufimian tectonic concentric structure could have contributed to the formation of complex Cu–Ag–Mo–Re ores (copper sands) at the upper boundary of terrigenous red deposits of the Zilmerdak Formation. Positive structures identified in the Neoproterozoic deposits near the margin of the Ufimian tectonic concentric structure are considered to be promising for searching for hydrocarbon fields.     

Depths to Lithospheric Magnetic Sources and Lithospheric Thermal Regime under the East Siberian Sea

Izvestiya, Physics of the Solid Earth - Abstract—We present the results of studying the depths to lithospheric magnetic sources under the East Siberian Sea. The azimuthally-averaged Fourier...