Using the Load/Unload Response Ratio and Self-Developing Processes Methods of Analyzing Seismic Sequences to Predict Earthquakes in Sakhalin

Izvestiya, Atmospheric and Oceanic Physics - The results of studying the seismic regime using the load/unload response ratio (LURR) and self-developing processes (SDPs) are considered. For the five...     

Correlation between the Earth’s outer radiation belt dynamics and solar wind parameters at the solar minimum according to EMP instrument data onboard the CORONAS-Photon satellite

The study of variations in the electron flux in the outer Earth radiation belt (ERB) and their correlations with solar processes is one of the important problems in the experiment with the Electron-M-Peska instrument onboard the CORONAS-Photon solar observatory. Data on relativistic and subrelativistic electron fluxes obtained by the Electron-M-Peska in 2009 have been used to study the outer ERB dynamics at the solar minimum. Increases in outer ERB relativistic electron fluxes, observed at an height of 550 km after weak magnetic disturbances induced by high-velocity solar wind arriving to the Earth, have been analyzed. The geomagnetic disturbances induced by the high-velocity solar wind and that resulted in electron flux variations were insignificant: there were no considerable storms and substorms during that period; however, several polar ground-based stations observed an increase in wave activity. An assumption has been made that the wave activity caused the variations in relativistic electron fluxes.     

Comparison of the geoacoustic measurements in boreholes with the data of laboratory and in-situ experiments on electromagnetic excitation of rocks

The data of borehole geoacoustic and electromagnetic measurements in Kamchatka are compared with the results of laboratory and field experiments on electromagnetic excitation of rocks. A noticeable similarity in the responses of the natural geological medium and rock specimens is observed. The field experiments with controlled electromagnetic sources show that the geophones placed in boreholes are capable of reliably detecting the responses of rocks in situ to electric impacts as low as 0.5 mV/m. The obtained results provide the experimental evidence in favor of the previously proposed hypothesis of modulation of geoacoustic emission in rocks in situ by the ULF atmospheric electromagnetic field.     

Isotopic structure and evolution of the continental crust in the East Transbaikalian segment of the Central Asian Foldbelt

New data on the geology and tectonics of the main structural elements of the East Transbaikalian segment of the Central Asian Foldbelt are discussed. Correlation charts of the main stratified and igneous complexes are compiled. The rocks of the Baikal-Patom and Baikal-Muya belts, as well as the Barguzin-Vitim Superterrane, are characterized by new Nd isotopic data, which have allowed us to establish the sources of these rocks, to separate isotopic provinces, and to distinguish two stages of crust-forming processes: the Early Baikalian (1.0–0.8 Ga) and the Late Baikalian (0.70–0.62 Ga). The Early Baikalian crust was formed in relatively narrow and spatially isolated troughs of the Baikal-Muya Belt and probably in the Amalat Terrane, whereas the Late Baikalian continental crust was formed and reworked in the Karalon-Mamakan, Yana, and Katera-Uakit zones of the Baikal-Muya Belt. The Baikal-Patom Belt and most of the Anamakit-Muya Zone in the Baikal-Muya Belt are characterized by remobilization of the Early Precambrian continental crust and by a subordinate role of Late Riphean juvenile sources. Reworking of the mixed Late Riphean and Early Precambrian crustal sources is typical of the Barguzin-Vitim Superterrane. The origination and evolution of the continental crust in the studied region are considered in light of new data; alternative versions of paleogedynamic reconstructions are discussed.     

Report on the 4th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the “Kilian Group” (Dijon, France, 30th August 2010)

The 4th Kilian Group meeting (Dijon, France, 30th August 2010) focused on the Aptian and Albian Stages. For the Aptian, a two-fold division of the stage was adopted for the Mediterranean area with a boundary between the Dufrenoyia furcata and Epicheloniceras martini Zones. The main changes to the zonal scheme concern the Lower Aptian with: the introduction of a Deshayesites luppovi Subzone in the upper part of the Deshayesites oglanlensis Zone; the replacement of Deshayesites weissi by Deshayesites forbesi as new index-species of the second interval zone; the introduction of a Roloboceras hambrovi Subzone in the upper part of the D. forbesi Zone; and the subdivision of the D. furcata Zone into the D. furcata and Dufrenoyia dufrenoyi Subzones. For the Albian, the upper part of the Douvilleiceras mammillatum Zone (Lower Albian) is now characterized by a Lyelliceras pseudolyelli Subzone. The main amendments concern the Upper Albian. The base of this substage is defined by the base of the Dipoloceras cristatum Zone. Above it, the Upper Albian zonal scheme comprises in stratigraphic order the Mortoniceras pricei, Mortoniceras inflatum, Mortoniceras fallax, Mortoniceras rostratum, Mortoniceras perinflatum and Arrhaphoceras briacensis Zones.     

Provenances of metaterrigenous sequences in the Sredinny and Ganalsky uplifts, Kamchatka in the light of New Sm-Nd isotopic data

Despite the long history of studying metamorphic rocks in the Sredinny and Ganalsky uplifts of Kamchatka, their tectonic setting and origin, as well as the time of sedimentation, magmatism, and metamorphism, remain a matter of debate and wide discussion. Our isotopic study shows that composite sections of metaterrigenous rocks of the Sredinny and Ganalsky ranges (Kolpakova, Kamchatka, Malka, Kikhchik, and Ganal groups) reveal no significant difference in the Nd isotopic composition, which is evidence for the geochemical similarity of their provenances in contrast to previous conjectures that these groups vary in age from Archean to Upper Cretaceous and were formed in regions distant from one another and distinct in geodynamic setting. New Sm-Nd isotopic data and recent U-Pb (SHRIMP II) timing of zircons allow us to state that the metaterrigenous rocks of the Sredinny and Ganalsky uplifts actually make up a single terrigenous sequence of a great thickness. This sequence accumulated in the Cretaceous shallow-water epicontinental basin, underwent contact metamorphism affected by intrusions varying in age and composition, was involved in zonal regional metamorphism in the early Eocene, and only in the Pliocene was it dismembered into the Sredinny and Ganalsky uplifts as a result of rifting.     

New U-Pb and Sm-Nd ages and P-T estimates for eclogitization in the Fe-rich gabbro dyke in Gridino area (Belomorian Mobile Belt)

New data from isotope geochronology (U-Pb, Sm-Nd) petrological study provide evidence of the Svecofennian age (～1.9 Ga) for eclogitization in the Fe-gabbro dyke inductile shear zones of Gridinrea. P-T estimates of eclogitization were computed using the THERIAK/DOMINO software. A close timing relationship between dyke magmatism and eclogitization is inferred.