The adsorption properties of a sand–gel material (SGM) with respect to mercury(II) ions were studied. It has been shown that studying adsorption under static conditions is inappropriate, since upon contact with the sorbent, oxalates pass into solution to form stable complexes with mercury, which are not susceptible to sorption. The adsorption of mercury on SGM reaches 0.21 mg/g; the adsorption capacity is 0.35 mg/cm3. It has been established that the studied material effectively adsorbs mercury(II) ions; therefore, it can be used for wastewater treatment with mercury contamination.

The methods of equilibrium–dynamic modeling have been applied to evaluate the probability of redeposition of previously formed Pb–Zn vein ore substances at a carbonate barrier upon reactivation of a hydrothermal system. The natural prototype is the Ursdon ore occurrence (Dzhimidon ore field, North Ossetia, Russia) in Oxfordian limestone (J3); the formation of polymetallic vein deposits of the region occurred in the pre-Callovian time of the Middle Jurassic. Calculations have been performed using the HCh software package, which includes the Unitherm thermodynamic database (the H–O–K–Na–Ca–Mg–Al–Si–Fe–C–Cl–S–Zn–Pb–Cu system described by 54 minerals and 78 particles of an aqueous solution). It has been established that late low-temperature hydrothermal solutions may provide pyritization, silicification, and the formation of Pb–Zn mineralization in carbonate rocks. The deposition of quartz and sulfides occurs along fractures and at the dissolution front of carbonate rocks.

The acid–base properties of the surface of Maikop series clays and mud volcano clays, as well as their adsorption properties with respect to mercury(II) ions, were studied. It is shown that pHPZC for the former is 7.1 on average; for the latter, 9.0. The pHPZC value for mud volcano clays is consistent with the pH values in the waters of mud volcanoes of the Kerch–Taman region. When the mass ratio of the sorbent and solution is 1 : 900, adsorption equilibrium occurs after 4 days with active stirring. Experimental data on mercury adsorption from NaCl–NaHCO3 solution on natural sorbents are best described by the Redlich–Peterson and Toth equations. The process of mercury adsorption on clays of the Maikop series is more intense than that on mud volcano clays.

An Erratum to this paper has been published: https://doi.org/10.1134/S0016702923210012

The Oulanka group is a compact group of three peridotite–gabbronorite intrusions that is convenient for testing various petrogenetic concepts. The three intrusions are similar in age and occur not far from one another but differ in the composition of their original magmas, are characterized by different sets of cumulus mineral assemblages, and are different in inner structure and rhythmic layering. We applied cluster analysis of the contents of major elements to reproduce the cumulus mineral assemblages of the isochemically altered rocks of the Tsipringa and Lukkulaisvaara massifs. Although the parental magmas of the Kivakka and Tsipringa massifs were of different composition and their crystallization sequences were also different, the vertical sections of these massifs can be clearly subdivided into zones according to their cumulus mineral assemblages, with the limited development of rhythmic interbedding (with individual rhythms ranging from a few to a few dozen meters in thickness). Conversely, the Lukkulaisvaara intrusion does not possess any clearly distinguishable cumulus zones, and large-scale rhythmic layering is traceable throughout the entire thickness of the massif (with rhythms ranging from a few dozen to a few hundred meters in thickness). The different character of the rhythmic layering of the three intrusions may provide an insight into the different scenarios of magma convection in the chambers.

Analysis of the distribution of rare-earth elements (REE) in veins and rocks of the Dzhimidonskii vein polymetallic deposit (North Ossetia, Russia) formed in the Middle Jurassic Period shows that the sources of REE and ore components were represented by a combination of host rocks of different compositions (PR3–PZ1 and PZ3) and alternated with time. Geochemical data were used as a basis for the development of new methods of equilibrium-dynamic modeling and assessment of the effect of the changes in space and with time of fluid flows from different sources on the processes of ore formation.

АННОТАЦИЯ: Для Джимидонского жильного полиметаллического месторождения (Северная Осетия, Россия), сформированного в среднеюрское время, по характеру распределения редкоземельных элементов в жилах и породах установлено, что источники РЗЭ и рудных компонентов являлись комбинацией различных по составу вмещающих пород (PR3-PZ1, PZ3) и сменялись во времени

This study discusses the presentation of rare-earth elements (REEs) in the rocks of the Kivakka Olivinite-Gabbronorite Layered Intrusion in North Karelia. It aimed to provide a detailed petrographic description of the mineral parageneses that are present in the studied section of the massif. We found that the same minerals can manifest in both intercumulative and cumulative positions, depending on the degree of melt fractionation. At the same time, their quantity, which determines both the petrographic characteristics and the name of the rock, is not a criterion for their presence during the cumulus phases. We analyzed the concentrations of REEs in rocks and rock-forming minerals in the Kivakka massif, considering the REE concentration vertically and in the critical zones of contrast interbedding. In the study area, REEs are present as incoherent elements and accumulate in the residual melt, together with U, Th, Zr, and other incoherent elements, which make them a useful indicator of the degree of melt fractionation. In some cases, they can reflect different structural and genetic characteristics, such as the degree of cumulus density in a specific type of cumulative paragenesis. The presence of hydrothermal changes is best reflected by a change in Ce concentration. The preservation of the stability of the configuration and the slopes of the lines on the spider diagrams for REE indicate that the process of crystallization differentiation took place in a closed system.

REE distribution patterns of the ores and host rocks of the Dzhimidon vein lead-zinc deposit (North Caucasus, Ossetia, Sadon mining district, Russia) have been analyzed to elucidate the source(s) of hydrothermal ore deposits. Two types of prevailing rocks are involved in ore formation - Paleozoic granites (the main ore-hosting rocks at the majority of deposits) and Precambrian schists (specific only the for host rocks of the Dzhimidon deposit). The source of ore components tends to be complex and includes host rocks in variable proportions that could be characterized by REE distribution in ores. Interaction of water with combined sources was thermodynamically modeled. Critical differences were found in the ore-forming models, with variable sequence and rock proportions during interaction with barren fluid.

Работа посвящена исследованию поведения редкоземельных элементов в породах Киваккского оливинит-габбро-норитового расслоенного интрузива (Северная Карелия). В статье приведена подробная петрографическая характеристика минеральных парагенезисов, слагающих разрез массива. Показано, что одни и те же минералы в породах могут занимать либо интеркумулятивную, либо кумулятивную позицию в зависимости от степени фракционирования расплава. При этом их количество, определяющее петрографические характеристики и название породы, не является критерием их присутствия в ассоциации кумулусных фаз (кумулятивной фазе). Представлены результаты анализа концентрации редкоземельных элементов в породах и породо­образующих минералах массива. Рассмотрено изменение концентрации РЗЭ в вертикальном разрезе, а также в критических зонах контрастного переслаивания. Показано, что в Киваккском массиве РЗЭ являются некогерентными элементами и накапливаются в остаточном расплаве совместно с U, Th, Zr и другими некогерентными элементами, что позволяет считать их индикатором степени фракционирования расплава. В некоторых случаях они могут отражать различные структурно-генетические особенности, такие как степень плотности кумулуса в однотипных кумулятивных парагенезисах. Наличие гидротермальных изменений наилучшим образом отражается в изменении концентрации Ce. Сохранение стабильности конфигурации и угла наклона линий на спайдер-диаграммах для РЗЭ свидетельствует о закрытости системы в процессе кристаллизационной дифференциации массива.

The analysis of the joint stability of phases and valence forms of mercury in the Hg – H2O system in the lg f O2 – 1/T coordinates for the temperature range from -50 to + 360°C was carried out by method of F. Schreinemakers. Analysis of equilibrium valence forms showed that for the composition of fluid phases, the non-autonomy of the oxide film as a phase on the surface of liquid mercury is key.

A system of equations of the liquidus thermobarometer of olivine — silicate melt was obtained by processing the sample of 772 experimental equilibria of olivines with basic melts using methods of multidimensional statistics. Equations reproduce with small error experimental data in a wide range of basite compositions (from komatiites to dacites), temperatures from 1040 to 1500 ᵒС, pressures from 1 bar up to 30 kbar. Thermobarometer testing demonstrated that the deviations of the calculated liquidus temperature from the experimental one in most of the temperature range do not exceed ±3 ᵒC.

На основе уравнения Кирхгофа разработан метод расчета энтальпии силикатного расплава произвольного состава с учетом скрытой теплоты плавления. Для достижения этой цели были решены две задачи: а) выполнена ревизия коэффициентов уравнения теплоемкости силикатного расплава; б) определены парциальные мольные энтальпии образования компонентов расплава из элементов в стандартном состоянии. Неопределенность при расчете теплоемкости силикатного расплава с использованием предлагаемого набора коэффициентов при уровне значимости 95% не превышает ±0.7 Дж · моль–1 · К–1. Установлена слабая, но статистически значимая температурная зависимость теплоемкости. Энтальпии расплавов, рассчитанные с использованием предложенного метода, сопоставлены со значениями, полученными независимыми методами. Значение ошибки при вычислении на уровне значимости 95% не превышает ±2 отн.%.

The Kirchhoff equation was used to develop a method for calculating the enthalpy of silicate melt of any arbitrarily chosen composition with regard for the latent heat of fusion. To do this, the following two problems were solved: (a) the coefficients of the heat capacity equation of a silicate melt were revised and (b) the partial molar enthalpies of formation of melt components from elements at standard state were determined. The uncertainty in calculating the heat capacity of silicate melt at 95% significance level is no greater than ± 0.7 J · mol–1 · K–1. A weak but statistically significant temperature dependence of the heat capacity was determined. The enthalpies of melts calculated using the method are comparable with the values obtained by other techniques. The calculation error at 95% significance level is ±2 relative %.

Abstract—This work is devoted to the examination of REE behavior in rocks of the Kivakka olivinite–gabbronorite layered intrusion (Northern Karelia). The paper reports detailed petrographic characteristics of mineral assemblages throughout the massif section. It is shown that the same minerals are present as both intercumulus and cumulus phases depending on the degree of melt fractionation. Their contents which determine the petrographic characteristics and rock name are not indicative of their presence in cumulate assemblage (cumulus phase). REE contents in rocks and rock-forming minerals are analyzed, including their variations in the vertical section as well as in the critical zones of contrasting intercalation. REE in the Kivakka massif behave as incompatible elements, are accumulated in a residual melt together with U, Th, Zr, and other incompatible elements, and can be used as indicator of the degree of melt fractionation. In some cases, they could reflect different structural–genetic features such as the cumulus density in the similar cumulus assemblages. Hydrothermal alteration strongly affects the Ce content. The similar shape of REE patterns indicates the close-system crystallization differentiation of the massif.

Data on the distribution of elements across the Pb-Zn section of the Gatsyrovskaya vein (Upper Zgid, North Ossetia, Russia) showed that during the formation of the vein significant changes in the spectra of rare-earth elements (REE) occur in ore samples. The sharp growth of ratios La N /Yb N , La N /Nd N , Gd N /Ho N , and Gd N /Yb N is confined to the vein intervals, where the maximum amount of ore components is deposited. A comparison of the REE spectra of ores with the characteristics of the spectra of the near-vein and host rocks suggests that the deposition of the vein material occurred from solutions whose compositions with respect to the REE varied with time. REE fractionation occurred due to the mobilization of components by hydrothermal solutions during their reaction with the host Paleozoic granites.

A liquidus thermobarometer for the magnetite–silicate melt equilibrium was obtained by processing of a sample of 93 experimental equilibria of magnetite with basic melts using the methods of multidimensional statistics. The equations reproduce experimental data in a wide range of basic compositions, temperatures, and pressures with low error. Verification of the thermobarometers shows that the maximum error in liquidus temperature reproduction does not exceed ±7°C. The level of cumulative magnetite in the vertical sections of the Tsypringa, Kivakka, and Burakovskii intrusions is predicted with errors from ±10 to ±50 m.

АННОТАЦИЯ: Методом Ф.А.Скрейнемакерса выполнен анализ совместной устойчивости фаз и валентных форм ртути в системе Hg -H 2 O в координатах lg f O 2 -1/T для интервала температур от -50 до +360°C.Анализ равновесий валентных форм показал, что для состава флюидных фаз ключевым является неавтономность оксидной пленки как фазы на поверхности жидкой ртути.Их одновременное участие в геохимических процессах и