Vol 64, No 11 (2019)


Sulfide mineralization of phoscorites and carbonatites of the guli massif (Polar Siberia) and potential of these rocks on noble metals

Sorokhtina N.V., Kogarko L.N., Zaitsev V.A., Konkova N.N., Asavin A.M.


A first complex investigation of mineral forms of Au and Ag and distribution of noble metals in sulfide-containing phoscorites and carbonatites, their magnetite and sulfide concentrates of alkaline ultrabasic massif Guli (Polar Siberia) was made by neutron activation method, XRF and microprobe analyses. Sulfide concentrates of carbonatites are enriched with Pt up to 2.93, Au up to 61.6 and Ag up to 3.61 (ppm).

The main sulfides are pyrrhotite, djerfisherite, chalcopyrite and pyrite. Silver is accumulated in the late chalcopyrite, Ag- djerfisherite, later ― lenaite, sternbergite or argentopyrite and native silver. Wide dissemination of djerfisherite in phoscorites and carbonatites and defined inclusions of rasvumite, K-Na-Ca carbonates, carbocernaite and strontianite in pyrrhotite, is the evidence of of high activity of K, Na, Sr, LREE, F, Cl and S during the sulfides crystallization. Chlorine has a high capacity for the formation of chlorine-silver complexes and is probably an agent for the transfer of noble metals in carbonatites.

The comparison of surveyed associations with published experimental data shows that formation of sulfides starts at the temperature no lower than 500°С (early pyrrhotite) and lasts till 150°C (argentopyrite). The late carbonatite assemblages may can be enriched with Au and Ag and be a potential source of formation of alluvial gold.

Геохимия. 2019;64(11):1111-1132
pages 1111-1132 views

Physico-chemical conditions of crystallization and ore-bearing of granitoids of the border zone of the Southern and Middle Urals

Snachev A.V., Snachev V.I., Znamenskyа S.E.


The geological structure of the border zone of the Southern and Middle Urals (Kunashak area), as well as the composition and conditions for the formation of granitoid complexes developed here, whose age varies from Devonian to Triassic, is briefly considered. Thermobarometric studies of quartz of medium-grained biotite granites showed that in the age range ― Poletaev (D3), Shalkar (P1), Sultayev (P1), and Yugokonev (P1−T2) complexes ― water pressure during the formation of melt inclusions was 2.2–2.7, 2.5–3.0, 3.9–4.4 and 3.6–4.5 kbar, and the crystallization temperature of rocks ― 800–840, 900–940, 840–900 and 940–980°С. This indicates a consistent increase in the crystallization depth of the granite massifs in this series from the hypabyssal-subsurface to the hypabyssal-abyssal facies. At the same time, in the melt-fluid inclusions, a decrease in fluid volume is noted ― 14.2–16.8, 8.1–14.3, 6.2–7.9 and 4.3–6.8 vol.%, Water concentrations ― 3.7–4.8, 2.1–3.9, 1.8–2.3 and 1.3–1.9 wt.% as well as chlorine ― 0.04–0.08, 0.03–0.07, 0.03–0.06 and 0.02–0.05 wt.%.

It is shown that the granitoids of the Sultayev and Yugokonev complexes are very promising for tantalum, niobium, tungsten, molybdenum and beryllium. Of the greatest interest in rare-metal mineralization are the leucocratic aplitic and greisen granites of the final phases of the formation of intrusions. The level of erosional slice of various structural and formation zones of the Kunashak area relative to each other has been established.

Геохимия. 2019;64(11):1133-1145
pages 1133-1145 views

Results of 13c nmr and ftir spectroscopy of kerogen of the upper devonian domanik of the Timan-Pechorian basin

Bushnev D.A., Burdel’naya N.S., Mokeev M.V.


A kerogen samples set from organic carbon rich rocks of the Middle Frasnian — Early Famennian age (Domanikites) of the Timan-Pechora basin, was characterized by the Rock-Eval pyrolysis data, solid-state 13C NMR spectroscopy and Fourier transform IR spectroscopy. Additionally, the spectral characteristics of kerogen isolated from rocks artificially maturated in an autoclave in the presence of water were investigated. In general, the direction of transformation of the kerogen structure with a natural or artificial maturation coincides. For kerogen, subjected to artificial maturation, is characterized by an increase in the concentration of terminal methyl groups in relation to the methylene units. Artificial maturation of kerogen leads to a more rapid rearrangement of aromatic clusters with the accumulation of bridgehead and protonated carbon as compared with natural maturation.

Геохимия. 2019;64(11):1146-1157
pages 1146-1157 views

Sedimentation rates (data on 210pb and 137cs radionuclides) in different facial-genetic types of the Kara sea bottom sediments

Rusakov V.Y., Borisov A.P., Solovieva G.Y.


In the article original data on isotope composition of natural “excess” Pb-210 and artificial Cs-137 radionuclides in upper 25–50-cm layer of sea-bottom sediments at the Kara Sea (from Ob’ and Yenisei estuaries, Eastern-Novaya-Zemlya trough, Voronin trough, as well as Sedov bay (Novaya Zemlya)) are presented. The research results showed close tie between sedimentation rates and facial-genetic types of the sea-bottom sediments. Highest sedimentation rates are typical for the terrigenic-estuarine type. The type is divided on tractional load with sedimentation rate 0.4–0.7 cm per year and “mud bank” sediments with sedimentation rate 0.7–1.0 cm per year. The terrigenic-shallow-marine type is characterized by lowest sedimentation rate – 0.1–0.3 cm per year. The background terrigenic-marine type has a broadest spectrum of the sedimentation rates: on trough slope the rates are minimal (likely to terrigenic-shallow-marine type), within central parts of the trough (as a result of gravity creep) the rates may increase up to 0.9 cm per year. Single facial-genetic type is glacial sediments of Navaya Zemlya bays. Measured recent sedimentation rate within inner depression of the Sedov bay is 0.1–0.2 cm per year.

Геохимия. 2019;64(11):1158-1174
pages 1158-1174 views

Distribution of dissolved matter in the Yenisei river estuary and adjacent water area of the Kara sea and its interannual variability

Savenko A.V., Pokrovsky O.S.


The distribution of dissolved matter (major ions, nutrients, and trace elements) in the Yenisei River estuary and adjacent water area was studied according to the natural observations data from 2009–2016. These results were compared to the literature data of hydrochemical researches of this region. It was shown that transport of major ions (Na, K, Mg, Ca, SO4) and some trace elements (Li, Rb, Cs, Sr, B, F, Cr, Ge, As, Mo, U) is described by the stable in the long-term period equations of conservative mixing between riverine and seawater masses. Alkalinity also belongs to conservative components; however this parameter exhibits substantial spatiotemporal variability of the distribution caused by complex hydrological structure of the Yenisei Bay and adjoining part of the Kara Sea. Concentrations of Pmin, Si, and V in the desalinized waters of photic layer decreases seaward during vegetation period owing to uptake by phytoplankton. The losses of these elements reach 30–57, 30, and 9% of their supply by river runoff, respectively. The content of dissolved Pmin and V in the intermediate and near-bottom layers of the Yenisei River estuary strongly increases with increase of salinity due to regeneration of precipitated organic matter, whereas silica remineralization is much less pronounced. Barium in the all estuary is intensively desorbed from river suspended matter in the quantity reaching 20–100% of its dissolved forms input with river runoff depending on seasonal variations of chemical composition of the last. The transport of dissolved forms of heavy metals (Mn, Fe, Pb) and elements-hydrolyzates (Al, Ti, Y, La, Ce, Pr) in the mixing zone between the riverine and seawater masses is probably controlled by the coagulation and flocculation of organic and organomineral colloids, which is indicated by decrease in the concentrations of these elements at the beginning of salinization (for 20–61%) with subsequent approximation to the seawater mass characteristics.

Геохимия. 2019;64(11):1175-1186
pages 1175-1186 views

Radionuclides distribution and its sorption behavior in the Kara sea bottom sediments surface layer

Kuzmenkova N.V., Krupskaya V.V., Duriagina E.V., Semenkov I.N., Vinokurov S.E.


The sorption characteristics of the Kara sea bottom sediments were investigated. The sediments were collected during scientific expedition of the R/V Akademik Mstislav Keldysh (Cruise AMK-66). The mineral and fraction composition of sediments was determined. It has been found that 137Cs sorbed predominantly by an ion exchange mechanism because of the clay minerals presence in the sediments. At the same time, 243Am and 90Sr sorbed from seawater by the surface complexation mechanism. The sorption kinetics for 243Am was established: about 20 hours, 137Cs: 2 hours, 90Sr: less than an hour. The sorption isotherms shows Cs and Am in experiments on marine and distilled water are described by the Henry equation. The Sr behavior in deionized water is described by the Langmuir equation, in the case of sea water, by the Freundlich equation.

Геохимия. 2019;64(11):1187-1195
pages 1187-1195 views

Short communications

Barium minerals – baritе and chlorinedominant ferrokinoshitalite bafe2+3[cl2/al2si2o10] in plagioperidotites Yoko-Dovyren intrusion (Northern Baikal region) – products of epigenetic low grad metamorphism

Spiridonov E.M.


In the plagioperidotite of the ultamafite-mafic Yoko-Dovyren intrusion captured by low-grad metamorphism (NGM) under conditions of the prenite-pumpelliite facies (PPF), mobilization of Ba, Cl and Sr is observed The content of barium in plagioperidotite ranges from 36 to 313 (an average of 130 g / t); strontium – from 25 to 169 (an average of 86 g / t); Ba / Sr value varies from 0.5 to 4 (on average 1.5). Barium minerals – phlogopite and plagioclase; chlorine – chloroferrisadanagite from inclusions in alumochromite, late-magmatic phlogopite, potassium chlorate ferropargassite and chlorapatite in the margins of sulphide nests. During the NGM processes, these minerals were replaced by chlorites, tremolite, diopside, which included very little Ba and Cl. In the areas of barium minerals development, plagioperidotites contain 348–518 g/t of barium and 4–6 g/t of strontium, which indicates the redistribution of Ba and the removal of Sr. Metamorphogenic barium minerals – non-strontium barite and Ba-Fe-Cl mica – chloro-dominant ferrokinochitalit. They coexist with the minerals of the rodingite association — hydrogarnet, tremolite, diopside, chlorite, antigorite, magnetite, hydroxylapatite. Ferrokosnoshitalit replaces phlogopite, plagioclase, sulfides, contains up to 21 wt. % BaO, 31% FeO, 11% Cl and has a iron index of f = 75.8–90.5. The composition of the most chlorine-rich individual responds (Ba0.83K0.16)0.99(Fe2+2.63Mg0.28Fe3+0.04Al0.02Cr0.01Mn0.01)3[(Cl1.86OH0.12S0.02)2/Al1.86Si2.14O10]. Since Yoko-Dovyrenskiy ferrokynosalital is chlordominant, this is a new mineral species.

Геохимия. 2019;64(11):1196-1205
pages 1196-1205 views

Facies structure and quantitative parameters of the Fiji sea pleistocene sediments

Levitan M.A., Antonova T.A., Koltsova A.V.


Lithological-facies zonality of Neo- and Eopleistocene sediments from the Fiji Sea is described firstly. Processing of corresponding maps and isopachite schemes by volumetric method of A.B. Ronov gave us an opportunity to calculate quantitative parameters of sedimentation for revealed different types of Pleistocene sediments. Carbonate sediments dominate among other groups of sediments. In Neopleistocene carbonate plankton sediments have been accumulated more intensively than in Eopleistocene. The highest volcanic-tectonic activity is typical for Eopleistocene.

Геохимия. 2019;64(11):1206-1212
pages 1206-1212 views

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