Vol 64, No 1 (2019)


Modification of Laptev sea freshened shelf waters based on isotope and salinity relations

Dubinina E.O., Miroshnikov A.Y., Kossova S.A., Shсhuka S.A.


This paper is dedicated to the estimation of the river runoff contribution to the Arctic shelf waters, where freezing and melting of desalinated waters are intensively proceeding. A mixing-modification model is offered. The model takes into account the sea ice formation from desalinated waters on the shelf. The model was used to explain the data obtained from 63 and 69 cruises of the research vessel “Akademik Mstislav Keldysh” (2015 and 2017). Two sources of water masses — the Atlantic waters and the Lena river were established for the studied area of Laptev Sea. The waters in this zone are modified, i.e. they have a higher salinity than the one that corresponds to the two components mixing. The presence of modified waters generated at the Laptev Sea shelf is traced in the continental slope zone. Desalination in the continental slope zone reaches 15–27% and affects depths no more than 20 m, at more than 50 m depths it is practically disappeared. A mixing-modification model was proposed to calculate river water input in the modified waters. The data obtained for the Laptev Sea shelf were used to calculate the fraction of river waters according to both the proposed model and the conventional three-component mixing model of Ostlund and Hut, 1984. A comparison of the estimates obtained by both models has shown that the application of the three-component mixing model to modified waters leads to an overestimation of the river water contribution, which can reach 20%.

Each sample of shelf waters can be processed using either a mixture-modification model or a three-component mixing model. To choose the appropriate model the special criterion is proposed. Using this criterion, the calculations of river water and melted ice contribution will be free from the unrealistic or negative values.

Геохимия. 2019;64(1):3-19
pages 3-19 views

Geochemistry and geochronology of cretaceous volcanism of Chauna region, Central Chukotka

Ganelin A.V., Vatrushkina E.V., Luchitskaya M.V.


New geochronological and geochemical data on the age and composition of Cretaceous volcanism of Palyavaam River basin (Central Chukotka, Chauna region) are presented. First complex is composed of rhyolites, ignimbrites and felsic tuffs of Chauna Group of Okhotsk-Chukotka volcanic belt (OCVB). Second complex is represented by volcanic rocks of latite-shoshonite series of Early Cretaceous age, distinguished as Etchikun’ Formation. Its origin is still debatable. Some researchers refer deposits of Etchikun’ Formation to magmatic stage before OCVB activity. Other authors include in Chauna Group composition. Obtained data indicate heterogeneity of Etchikun’ Fomation volcanics and allow to divide them in two groups. Andesites of the first group (Etchikun’ Formation sensu stricto) have Early Cretaceous age and belong to magmatic stage before OCVB activity. Andesites of the second group correlate in age and composition with OCVB volcanic rocks. They occur at the base of Chauna Group and indicate homodromous character of volcanism evolution in the Central-Chukotka of Okhotsk-Chukotka volcanic belt.

Геохимия. 2019;64(1):20-42
pages 20-42 views

Hg- and Cd-bearing Pd, Pt, Au, AND Ag minerals in sulfide-bearing mafic and ultramafic rocks of the Yoko-Dovyren intrusion in the baikalides of the Northern Baikal area

Spiridonov E.M., Orsoev D.A., Ariskin A.A., Nikolaev G.S., Kislov E.V., Korotaeva N.N., Yapaskurt V.O.


Hg and Cd are rare chemical elements found in magmatic PGE and Au mineralization and typical of this mineralization in the Late Riphean Yoko-Dovyren plagioperidotite–troctolite–gabbronorite intrusion hosted in the Baikalides of the Baikal area. The paper discusses variations in the composition, associations, and distribution traits of the Hg- and Cd-bearing Pt, Pd, Au, and Ag minerals. Many of the precious-metal minerals are Pt, Pd, and Au chalcogenides and intermetallic compounds of postmagmatic genesis and occur as single crystals and stringers in sulfides and silicate matrix and at their contacts. The minerals were formed with the participation of fluids from the crystallizing Cu–Fe–Ni sulfide melts. They are constrained to the central part of the intrusion and found in sulfide-bearing plagiolherzolite (PL) in the lower part of the intrusion, in sulfide-bearing pegmatoid troctolite (T) in the bottom portion of the troctolite unit, and in sulfide-bearing pegmatoid anorthosite (A) in the top part of the troctolite unit. From PL to T and further to A, the content and diversity of the Hg-bearing minerals remarkably increase, with Hg distributed in these minerals very unevenly, and with Cd-bearing minerals identified only in A. The leading Hg concentrators in T and A are pneumatolytic (fluid–metasomatic) moncheite and, particularly, later telargpalite (Pd,Ag)3(Te,Pd,Hg), which contains up to 11 wt % Hg. The latter mineral is sometimes found in association with Hg-electrum, kustelite, and potarite. Potarite in T is Pb-rich, and this mineral in A is Pb-free. Appreciable Hg concentrations in precious-metal minerals in the Yoko-Dovyren intrusion suggest that these minerals crystallized in a closed system at high temperatures. Potarite content in A is much higher, and Hg concentration in telargpalite in A is notably lower (2.9 wt % Hg on average) than in this mineral in T (5.9 wt % Hg on average). The potarite might have been produced by epigenetic serpentinization processes (low-grade metamorphism) at the expense of the material of pneumatolytic Hg-bearing telatgpalite, kotulskite, and zvyagentsivite. This corresponds to specifics in Hg distribution in the telatgpalite, kotulskite, and zvyagentsivite in T and A and much higher intensity of metamorphism.

Геохимия. 2019;64(1):43-58
pages 43-58 views

REE–Th systematics of the suspended particulate matter and bottom sediments from the mouth zones of the world rivers of different categories/classes and some large Russian Arctic rivers

Maslov A.V., Shevchenko V.P.


The distribution of the rare-earth elements (REE) and Th in the suspended particulate matter (SPM) of some large Russian Arctic rivers and in the bottom sediments from the mouth zones of the world rivers of large categories/classes is compared. It is concluded that the fine (pelite and silt-pelite) material of the Russian Arctic rivers belongs mainly to classes 1 + 2 (large rivers and rivers draining areas made up mainly of sedimentary rocks) and 4 (SPM of rivers draining volcanic areas) of the world rivers. The SPM similar in terms of REE and Th distribution to the bottom sediments of the mouth zones of category/class 3 (rivers draining mainly metamorphic/magmatic terranes) are not typical of the Russian Arctic rivers, except for the SPM of the Lena River similar in terms of (La/Yb)N and Eu/Eu* ratio.

Геохимия. 2019;64(1):59-78
pages 59-78 views

Composition and distribution of saturated hydrocarbons in the thermal waters and vapor–water mixture of the Mutnovskii geothermal field and Uzon caldera, Kamchatka

Poturay V.A., Kompanichenko V.N.


The paper presents data on the composition and molecular-mass distribution of saturated hydrocarbons in sterile vapor–water mixture from wells and in high-temperature springs in the Mutnovskii hydrothermal area and Uzon caldera. The condensate of the vapor–water mixture and thermal waters from the Mutnovskii area contain low-molecule n-alkanes, which were generated by thermogenic processes. The boiling mud pot of the Donnoe fumarole field typically contains hydrocarbons whose origin is likely related to thermocatalytic transformations of the biomass of thermophilic microorganisms. A separate type of the molecular-mass distribution is typical of the geyser in the caldera of Uzon volcano: this material contains n-alkanes, which were generated by two processes: chemical re-synthesis of floral organic remnants and biogenic synthesis with the probable involvement of bacteria and algae.

Геохимия. 2019;64(1):79-88
pages 79-88 views

Short communications

Investigation of interaction of Co, Mn and Fe atoms with the calcite by X-ray photoelectron spectroscopy

Magkoev T.T., Zaalishvili V.B., Burdzieva O.G., Tuaev G.E., Grigorkina G.S.


Adsorption of atoms of Co, Mn, Fe on the calcite surface in ultra-high vacuum and the interaction of the formed adsorption systems with the water have been studied by means of X-ray photoelectron spectroscopy. It is shown that Mn and Fe form solid solutions CaCO3/Mn(Fe)CO3 on the calcite surface, whereas Co preferentially forms CoO and Co3O4. Upon interaction with water the surface compounds formed by Mn and Fe do not undergo notable changes, unlike the Co oxides which partially transform into soluble hydroxylated complexes.

Геохимия. 2019;64(1):89-95
pages 89-95 views

About salt fractionation in the process of terrigenous aerosol generation

Savenko A.V., Savenko V.S.


The content of water-soluble salts in samples of surface soils from arid regions and separated from them fraction <0.1 mm was analyzed. Existence of salt fractionation in the aleurite was shown. The fractionation coefficients, defined as the ratio of ions concentrations in the water extracts from fraction <0.1 mm and soil as a whole, are arranged in the successions: Na > K > Mg > Ca and SO4 > HCO3 > Cl. It was found that the fractionation of salts depends on their solubility: than solubility below, that enrichment of soils fine fraction is more.

Геохимия. 2019;64(1):96-100
pages 96-100 views

Standard enthalpy of formation kesterite Cu2ZnSnS4

Stolyarova T.A., Osadchii E.G., Baranov A.V.


The standard enthalpy of kesterite formation (Cu2ZnSnS4) is calculated from the calorimetric determinations of the enthalpy of its formation from simple sulphides: 2CuS + ZnS + SnS → Cu2ZnSnS4 using literature data on the standard enthalpies of the formation of simple sulphides. As a result, the standard enthalpy of kesterite formation was determined: ΔfHo298.15 (Cu2ZnSnS4) = -(467.62±2.28) kJ mol-1.

Геохимия. 2019;64(1):101-104
pages 101-104 views

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