Search

The results of complex studies of the northeastern fumarole field of the Ebeko Volcano (Paramushir Island) are presented. The geochemical study of the thermal sources and potholes evidences the complex composition of the solutions: the high contents of certain chemical elements in the sources cannot be explained only by leaching from the host rocks. To identify the structural features that can lead to accumulation of elements in the thermal solutions, the geophysical study of the northeastern fumarole field of the volcano is carried out by frequency sounding, electric tomography, and temperature surveying along the profile. As a result, the structure of the subsurface space of the thermal field, the structure of the feeders, and the presence of a phase barrier for fluid separation are revealed. The complex of studies makes it possible to explain some features of the geochemical composition of the thermal sources and to describe the evolution of the fluids in the upper segment of the section. [ABSTRACT FROM AUTHOR]

Based on geochemical studies we have updated our knowledge of the generation conditions and discharge of thermal waters on Shiashkotan Island. The thermal springs, which are abundant on the island, are surface expressions of the North Shiashkotan and Kuntomintar hydrothermal systems. The North Shiashkotan hydrothermal system shows the classical hydrochemical zonality. The discharge of the Kuntomintar hydrothermal system is confined within two thermal fields that are situated in the central and northeastern craters of the eponymous volcano. The high temperature of the gases that are issuing from Kuntomintar Volcano to the ground surface and the higher predictive ratios S/Cl, S/C, and CO/H in its composition provide evidence of a possible renewal of its fumarole activity. [ABSTRACT FROM AUTHOR]

The first results of tephrochronological studies of the Sarychev Peak volcano on Matua Island in the Central Kuril Islands are presented and the eruptive evolution of the volcano in the Holocene is reconstructed. The volcanic products are typified and the general style of their geochemical evolution is reviewed on the basis of the distribution of the petrogenic oxides and trace elements in tephra samples taken bed-by-bed from the reference section of the soil-pyroclastic cover on Matua Island. The horizons of transit ashes are identified. [ABSTRACT FROM AUTHOR]

This paper reports the results of geological studies at the submarine Vityaz Ridge carried out during cruises 37 and 41 on the R/V 'Akademik Lavrent'ev' in 2005 and 2006. The studied area is located at the near-island trench of the slope in the central part of the Kurile island arc. Morphologically, it consists of two parts: inner volcanic arc represented by the Great Kurile Range and outer arc corresponding to the submarine Vityaz Ridge. Diverse rocks that compose the basement and sedimentary cover of the ridge were recovered by dredging. Based on K-Ar dating and geochemistry, the volcanics were divided into Paleocene, Eocene, late Oligocene, and Pliocene-Pleistocene complexes. Each of the distinguished complexes reflects the tectonomagmatic stage in the ridge evolution. The geochemical and isotope data on the volcanics indicate the contribution of ancient crustal material in magma source and, correspondingly, the formation of this structure on the continental basement. Two-stage model ages, T, vary in a wide range from zero values in the mafic rocks to 0.77 Ga in felsic varieties, pointing to the presence of Precambrian protolith in the source of the felsic rocks of the Vityaz Ridge. The Pliocene-Pleistocene volcanics are classed with the tholeiitic, calc-alkaline, and subalkaline series, which differ in alkali contents and REE fractionation. The values of (La/Sm) and (La/Yb) ratios vary from 0.74 and 0,84 in the tholeiitic varieties to 1.19 and 1.44 in the calcalkaline and 2.32 and 3.73 in the subalkaline rocks. All three varieties occur within the same volcanic edifices and were formed during differentiation of magmatic melt that were channeled along fault zones from the mantle source slightly enriched in crustal component [ABSTRACT FROM AUTHOR]

The article offers information on the concentration of rhenium at the Kudryavy Volcano in Iturup Island, Kurile Islands, Russia. The authors noted a 2002 experimental study of the Institute of Mineralogy, Geochemistry and Crystal Chemistry, which demonstrated crystallization of rhenium from hot fumarole gases with temperature of 500-550 degrees Celsius. This finding is the first in the world using a natural sorbent, zeolite. However, 2009 data on the metal concentration in gases at the same site are contradictory, with rhenium content differing by three orders of magnitude. In order to obtain a real data on rhenium concentration, kinetic method and metals in solutions approach were employed.

Examines cross-arc geochemical variations in the Kuril Islands, Russia. Trace element systematics in suites of lava; Variations related to changes in fluid composition; Enrichment factors for elements with strong affinities for water.