Specificity of the products of Tyatya volcano eruption in 1973

Based on 198 determinations of the complete silicate analysis of Tyatya volcano (Kunashir Island), we compared the data of the latter (1973) and all previous eruptions to reveal their differences and determine the evolution of Tyatya volcanism in the Holocene. The application of the estimation of the thermobaric parameters of the upper mantle magma chamber of the volcano made it possible to determine the temperature decrease in the magma chamber in 1973. An assumption was made about the polycyclic magmatic activity of the Tyatya volcano. The results of statistical processing of data on the thickness of tephra and the size of its fragments from the 1973 eruption are presented. Polynomial regressions of various degrees are applied. Models of tephra distribution based on three-dimensional trend analysis have been constructed. The results of the study are recommended for the creation of information databases on the petrochemistry of eruption products and the distribution of pyroclastics from volcanoes in the Kuril Island arc.

Genesis and Nd Isotope Composition of Ferromanganese Deposits of the Sea of Okhotsk and the Kuril Island Arc

—The Nd isotope composition of ferromanganese deposits (FMD) from the central part of the Sea of Okhotsk and the Kuril island arc has been studied. The results showed that diagenetic samples from the Deryugin Basin have a heterogeneous Nd isotope composition. The positive εNd values here might be both due to the input of a terrigenous impurity and due to diffuse endogenetic element supply. The FMD samples from the Sonne underwater ridge show a εNd value specific to seawater (–3.2). The εNd value of hydrogenetic FMD from Volcano 7.14 is –3.4, which corresponds to the εNd value of the Pacific water. The FMD samples from Volcano 5.5 are characterized by εNd = –2.0. The higher εNd value might be due to a moderate dilution of the hydrothermal fluid by seawater and might also indicate the presence of volcanic fragments in the FMD samples. The highest εNd value (+4.4) has been established for volcaniclastic sandstone saturated with Fe and Mn hydroxides. It points to a mixing of volcanomictic and hydrothermal materials.

Genesis of the Russia-Japan Conundrum in Northeast Asian Security: The Anatomy of Mutual Distrust and the China Factor

This paper examines the potential and limits of Russo-Japanese bilateral relations across the Gorbachev, Yeltsin and Putin periods, exploring the roots of the mutual distrust between the two countries, Gorbachev’s “new thinking” with respect to Japan, how Yeltsin’s policy differed from Gorbachev’s, what Putin’s policy priorities were with Abe, and the limits of Russo-Japanese relations. I also analyze important external elements in bilateral relations such as the China factor, predict how Russian relations with Japan will affect Russia’s future role in Northeast Asia, and discuss policy implications for Republic of Korea as well. The main argument of this paper is that Japan and Russia will continue to remain as immiscible in the end even before economic relations fully heated. Kuril Island dispute along with inherent mistrust between the two sides will continue to obstruct bilateral relations for the indefinite period unless there is a shocking event such as Russia’s decision to yield the four islands in contention to Japan.

ATAKAMIT AS A PRODUCT OF FUMAROLE MINERAL FORMED ON MODERN ON VOLCANOES

The results of electron microscopic, X-ray, IR-spectroscopic and X-ray microprobe studies of atacamite mineralization of fumarole origin on Alaid volcano (Kuril island arc) are discussed.

COMPLEX GEOLOGICAL-GEOPHYSICAL STUDIES OF THE UNDERWATER VOLCANO 7.10 (KURIL ISLAND ARC)

Submarine volcano 7.10, which is part of the North Iturup group of submarine volcanoes of the Kuril island arc, was studied in 5 voyages of the research vessel Vulkanolog in 1982–1989. Comprehensive studies have shown that the edifice of the 7.10 submarine volcano is composed of rocks of a range from dacites to basalts. The summit and slopes of the volcano are devoid of sediments, and the base is overlain by a sedimentary stratum, thickness of which reaches 800 m. The minimum depth recorded above the top of the volcano is 210 m. In the volcanic edifice, subvertical, northeastern and northwestern feeder channels, as well as peripheral magma chambers at depths of 2.5–3.0 km, were identified. It is assumed that during the terminal eruption, small lava flows poured out in the northeast and southwest directions, while the main lava flow poured out in the southeast direction and reached the base of the volcanic edifice.