41 research outputs found
Сучасні стратегії розвитку науки
Робоча програма з дисципліни «Стратегії розвитку науки» за спеціальністю 6.030302 «Реклама та зв’язки з громадськістю» галузі знань 0303 «Журналістика та інформація», освітньо-кваліфікаційного рівня «бакалавр». – 2016. – 48 с
Petrological and geochemical evolution of the Tolbachik volcanic massif, Kamchatka, Russia
Petrological and chronological study of primitive high-Mg andesite from monogenetic volcanoes in the fore-arc region of northern Kamchatka Peninsula
Primitive high-Mg andesites (HMA) exhibit low FeO*/MgO (FeO*, total iron) and high Mg# (=100×Mg/(Mg+Fe)), and are thought to be generated by hydrous mantle melting (Kushiro, 1969). HMA, including sanukitoids of the Setouchi volcanic belt, have been recognized in many orogenic belts of various ages, and in several cases, constitute a part of ophiolite (Tatsumi, 2003). Therefore, occurrence of HMA in northern Kamchatka may have important implications on the tectonic setting of the peninsula and/or the melting condition underneath
Petrology and geochemistry of the Tolbachik stratovolcano
The numerous of national and international publications were dedicated to Plosky Tolbachik volcano eruptions and adjacent monogenetic cones, which were erupted repeatedly during Holocene, including historical time [i.e. Vlodavets, 1937; Popkov, 1946; Peep, 1946, 1954; Menyailov, 1953; Sirin and Farberov, 1963; Kirsanov et al., 1974; Ivanov and Khrenov, 1979; Fedotov, 1984; Krivenko, 1990; Kersting, 1995; Tatsumi et al., 1995; Hochstaedter et al., 1996; Kepezhinskas et al., 1997; Turner et al., 1998; Pineau et al., 1999; Volynets et al., 2000; Churikova et al., 2001; Münker et al., 2004; Portnyagin et al., 2007; Volynets et al., 2013]. However, all these data mainly relates to monogenetic cones, but the information on stratovolcanoes itself practically absent. There are only few papers on Ostry and Plosky Tolbachik stratovolcanoes focusing on geology [Ermakov and Vazheevskaya, 1973], petrography and some petrochemistry of the rocks [Ermakov, 1977; Flerov and Melekestsev, 2013]. The modern geochemical and isotope studies of the stratovolcanoes were never achieved. In this report we present geological, petrographical, petrochemical, geochemical and some K-Ar data on the rocks of Tolbachik massif. The present report based on representative collection of 154 samples from stratovolcanoes, dikes, monogenetic cones of different ages, including last 2012-2013 eruption. Additionally our study included samples separately standing edifice of Povorotnaya mount, which age according to K-Ar dating is 0.306±0.01 Ма
Sudden Hearing Loss in a Young Patient with Chronic Myelogenous Leukemia
Hyperleukocytosis is a typical presentation of chronic myelogenous leukemia (CML). It sometimes induces leukostasis, the symptoms of which include visual change, headache, tinnitus, dizziness, and occasional disturbance of consciousness. In the present study, a 26-year-old male patient visited a general physician, who observed marked hyperleukocytosis and referred the patient to our hospital. The patient was diagnosed with CML and treated with a tyrosine kinase inhibitor and hydroxycarbamide. On the fourth day after admission, the patient suddenly complained of left-sided hearing loss. An audiogram revealed profound left sensorineural hearing loss. Magnetic resonance imaging of the head showed no lesions in the inner ear, cerebellum, or brain stem; therefore, we diagnosed sudden hearing loss due to leukostasis. Subsequently, his hearing did not improve, despite a decrease in leukocytes. The pathophysiology of leukocytosis involves increased leukocytes and thrombi, which induce high blood viscosity in the microcirculation. Leukostasis-related infarction and hemorrhage can lead to occlusion of the labyrinthine artery, causing deafness. Physicians should be aware that deafness can develop when diagnosing marked leukocytosis because such deafness is irreversible in most cases
Petrographic and isotopic characteristics of hornblende-bearing cumulates and pyroxene granulite xenoliths from Kampu volcano, Oga peninsula, Northeast Japan Arc: High-pressure crystallization of hornblende and metasomatism of lower crustal material
Slab-mantle thermal structure beneath northeast Kamchatka Peninsula constrained from high-Mg basalts and andesites
Genesis of Quaternary volcanism of high-Mg andesitic rocks in the northeast Kamchatka Peninsula
Arc magmatism is a product of subduction factory, involving thermal and chemical interactions
between a subducted slab as a material input and mantle wedge as a processing factory. In turn, the
compositions of arc magma provide invaluable information concerning the material input and the
interactions. The northeast Kamchatka Peninsula is an ideal field to examine such interactions and
relationships, being characterized by (1) subduction of the Emperor Seamount Chain (Davaille and
Lees, 2004), and (2) possible material and thermal interaction among the subducted slab, the
overlying mantle wedge and the sub-slab mantle via the edge of subducted Pacific slab (Portnyagin
and Manea, 2008). Within this area, a monogenetic volcanic group occurs along the east coast,
including high-Mg andesitic rocks and relatively primitive basalts (East Cones, EC (Fedorenko,
1969)). We have conducted geochemical studies of the EC lavas, with bulk rock major and trace
elements, and K-Ar and Ar-Ar ages, based on which a possible contribution of subducted seamounts
and its relation to the tectonic setting are discussed.
The elemental compositions indicate that the lavas from individual cones have distinct mantle
sources with different amounts and/or compositions of slab-derived fluids. Based on mass balance,
water content and melting phase relations, we estimate the melting P-T conditions to bet ~1200 ℃
at 1.5 GPa, while the slab surface temperature is 620 –730 ℃ (at 50-80 km depth). Compared with
the southern part of Kamchatka, the slab surface temperature beneath EC seems to be high due to the
thinner Pacific slab associated with the seamount chain and/or the plate rejuvenation from a mantle
plume impact (Davaille and Lees, 2004; Manea and Manea, 2007).
The K-Ar and Ar-Ar ages of the Middle Pleistocene are consistent with the tephrochronological
study (Uspensky and Shapiro, 1984) and the present tectonic setting after 2 Ma (Lander and Shapiro,
2007). The high-Mg andesite with the highest SiO2 content in the EC lavas shows the oldest age
(0.73 ±0.06 Ma) within not only EC but also the northeast part of Kamchatka (e.g., Churikova et
al., 2015, IAVCEI). On the other hand, the rest of EC lava samples show relatively younger ages to
0.18 ±0.07 Ma. These results suggest that the EC lavas including high-Mg andesite and basalt were
generated by mantle flux-melting induced by dehydration of a subducted seamount inheriting a local
thermal anomaly (Nishizawa et al., 2014, JpGU; 2015, JpGU)