Clastic Rocks from Permian and Triassic Cherty Sequences in Sikhote Alin and Japan

Specific structural–textural and mineralogical–petrographic features of clastic rocks, which make up sparse thin layers within Permian and Triassic cherty sequences in Sikhote Alin and Japan, are discussed. The cherty sequences were retained in the Jurassic accretionary complex as fragments of sedimentary cover of an ancient oceanic basin. They were mainly formed by turbidity currents that originated on intrabasinal uplifts composed of tholeiitic basalts in the Permian. In the Triassic, the currents originated on uplifts consisting of ocean-island alkali basalts along with Permian and Lower Triassic cherty and cherty–clayey rocks. The compositional difference of provenances was apparently caused by tectonic events in the oceanic basin at the Permian/Triassic boundary.     

Deflection of Coronal Rays by Remote CMEs: Shock Wave or Magnetic Pressure?

We analyze five events of the interaction of coronal mass ejections (CMEs) with the remote coronal rays located up to 90° away from the CME as observed by the SOHO/LASCO C2 coronagraph. Using sequences of SOHO/LASCO C2 images, we estimate the kink propagation in the coronal rays during their interaction with the corresponding CMEs ranging from 180 to 920 km s⁻¹ within the interval of radial distances from 3 R _⊙ to 6 R _⊙. We conclude that all studied events do not correspond to the expected pattern of shock wave propagation in the corona. Coronal ray deflection can be interpreted as the influence of the magnetic field of a moving flux rope within the CME. The motion of a large-scale flux rope away from the Sun creates changes in the structure of surrounding field lines, which are similar to the kink propagation along coronal rays. The retardation of the potential should be taken into account since the flux rope moves at a high speed, comparable with the Alfvén speed.     

Multiwavelength Study of the M8.9/3B Solar Flare from AR NOAA 10960

We present a multiwavelength analysis of a long-duration, white-light solar flare (M8.9/3B) event that occurred on 04 June 2007 from AR NOAA 10960. The flare was observed by several spaceborne instruments, namely SOHO/MDI, Hinode/SOT, TRACE, and STEREO/SECCHI. The flare was initiated near a small, positive-polarity, satellite sunspot at the center of the active region, surrounded by opposite-polarity field regions. MDI images of the active region show a considerable amount of changes in the small positive-polarity sunspot of δ configuration during the flare event. SOT/G-band (4305 Å) images of the sunspot also suggest the rapid evolution of this positive-polarity sunspot with highly twisted penumbral filaments before the flare event, which were oriented in a counterclockwise direction. It shows the change in orientation, and also the remarkable disappearance of twisted penumbral filaments (≈35?–?40%) and enhancement in umbral area (≈45?–?50%) during the decay phase of the flare. TRACE and SECCHI observations reveal the successive activation of two helically-twisted structures associated with this sunspot, and the corresponding brightening in the chromosphere as observed by the time-sequence of SOT/Ca?ii H line (3968 Å) images. The secondary, helically-twisted structure is found to be associated with the M8.9 flare event. The brightening starts six?–?seven minutes prior to the flare maximum with the appearance of a secondary, helically-twisted structure. The flare intensity maximizes as the secondary, helically-twisted structure moves away from the active region. This twisted flux tube, associated with the flare triggering, did not launch a CME. The location of the flare activity is found to coincide with the activation site of the helically-twisted structures. We conclude that the activation of successive helical twists (especially the second one) in the magnetic-flux tubes/ropes plays a crucial role in the energy build-up process and the triggering of the M-class solar flare without a coronal mass ejection (CME).     

Manifestation of marine and riverine factors in the tide and ebb phases along the white sea coasts of different configuration

The peculiarities of the distributional patterns of the water temperature, salinity, current velocities, particulate matter concentration, bottom contour, and zooplankton abundance were studied in relation to the marine-riverine interactions and tide/ebb phases for coast lines of different configurations in the White Sea during the cruises of the R/V Ekolog (August of 2006 and 2007). A significant difference in the manifestation of the combined effect of the marine and riverine impacts (the estuarine concave relief) and only the marine impact (the open-sea straight-line portion) was observed, which results in both variations in the sea water level and the distributional patterns of the suspended matter and the zooplankton.     

New finds of middle and late jurassic radiolarians in the siliceous-clayey and clastic rocks of the Nadan’khada-Bikin terrane (Jurassic accretionary wedge, western Sikhote Alin) and their geological significance

The lithostratigraphic analysis of the paleo-oceanic sediments in the Bikin segment of the Nadan’khada-Bikin terrane of the Jurassic accretionary wedge revealed late Bajocian and early to middle Bathonian radiolarians in the siliceous-clayey rocks constituting its southern part in the Perepelinaya-Cheremshanka and Kedrovka areas. Siltstones from the central part of the Bikin segment in the upper reaches of the Vasil’eka River contain radiolarians of the terminal late Tithonian age. Combined with the known dates available for siliceous-clayey rocks from the western part of the Nadan’khada Alin Range and the Ulitka-Zolotoi Klyuch area, these data made it possible to define three stages in the formation of the Bikin segment of the Nadan’khada-Bikin terrane of the accretionary wedge: the terminal Middle Jurassic, the late Tithonian, and the Berriasian. The formation of this segment lasted approximately 25 Ma.     

Low Values of the Critical Decay Index of the Magnetic Field in Prominence Eruptions

Geomagnetism and Aeronomy - An attempt has been made to estimate with the highest possible accuracy the critical value of the decay index of the coronal magnetic field nc in eruptions of...     

Two Scenarios for the Eruption of Magnetic Flux Ropes in the Solar Atmosphere

Eruptions of material from lower to upper layers of the solar atmosphere can be divided into two classes. The first class of eruptions maintain their (usually loop-like) shapes as they increase in size (eruptive prominences), or display a sudden expansion of fairly shapeless clumps of plasma in all directions (flare sprays). The second class refers to narrow, collimated flows of plasma on various scales (spicules, surges, jets). It is obvious that the magnetic configurations in which these phenomena develop differ: for the first class they form closed structures that confine the plasma, and in the second class open structures directing flows of plasma in a particular direction, as a rule, upward. At the same time, the mechanisms initiating eruptions of both classes could be similar, or even practically identical. This mechanism could be instability of twisted magnetic tubes (flux ropes), leading to different consequences under different conditions. It is shown that the results of eruptive instability are determined by the ratio of the scales of the magnetic flux rope and the confining coronal field, and also by the configuration of the ambient magnetic field in the corona. Observations of both types of eruptions are analyzed, the conditions for their develoment are examined, and phenomenological models are proposed.     

Analysis of the landscape structure in the tundra zone for western Siberia based on satellite data

The landscape structure are investigated for typical and southern tundra subzones of western Siberia based on satellite images from Landsat and WorldView. The microlandscape types for the considered regions are selected and areas of microlandscapes are defined on the basis of satellite information and accounting data of field studies. The areas of the main wetland landscapes in the different types of bogs in northwestern Siberia are defined.