The paper presents data on the composition of condensate vapor–gas flows sampled in summertime on the surface of dumps of processing products of mining wastes. The data make it possible to assess the migration capacity of major and trace elements in the gas phase depending on the mineral composition of the anthropogenic materials and the physical and chemical characteristics of the water extracts (mobile fraction). The condensates of the vapor–gas mixture sampled above the surface of the tailings were analyzed for a wide range of chemical elements, including major elements (Ca, Mg, Na, K, Al, and Mn), metals (Cu, Zn, Pb, Cd, Co, Ni, and Ag), and metalloids (As and Sb). The concentrations of these elements in the condensates depend on both their contents in the solid waste and the amount of mobile (water-soluble) forms. Comparison of the ratios of geochemically related elements in the different phases led us to elucidate the mobility of the elements when they form volatile species. The data on the amounts of elements that migrate with the vapor–gas phase demonstrate that contrasting anomalies form in the near-surface layer of the atmosphere, and this is confirmed by the composition of the rainwater sampled at different times in the neighboring areas.
Evaporation of crystalline and liquid wollastonite from a molybdenum cell was studied by Knudsen effusion mass spectrometry in the temperature range 1751–2087 K. Molecular species typical of simple oxides and gaseous CaSiO3 were identified in the gas phase over wollastonite. Partial pressures of vapor species over wollastonite were determined for the first time. The determination of oxide activities in wollastonite made it possible to calculate the enthalpy and entropy of mixing: –38.92 ± 0.52 kJ/mol and 2.33 ± 0.29 J/(mol K), as well as the enthalpy of CaSiO3 melting at 1818 ± 7 K: 27.64 ± 0.57 kJ/mol. Based on this information, the mixing enthalpy and entropy in rankinite (Ca3Si2O7) were estimated in the temperature range 1600–1737 K: –42.63 ± 0.63 kJ/mol and 2.39 ± 0.35 J/(mol K), which are similar to the available thermochemical data. It was shown that redox interaction with the effusion cell material was mainly due to molecular oxygen, the amount of which decreased significantly compared with atomic oxygen in the absence of interaction. The behavior of wollastonite melt follows the patterns typical of other melts of compounds found in the refractory calcium–aluminum-rich inclusions in chondrites.
A physicochemical study of murmanite from the Alluaiv alkaline pegmatites (Lovozero Massif, Kola Peninsula) was conducted using powder X-ray diffraction, electron microprobe analysis, IR and Raman spectroscopy, and thermogravimetric analysis. The empirical formula of the studied murmanite is ( Na_3.3Ca_0.3K_0.1□_0.3)_Σ4.0 ( Ti_3.1Nb_0.3Zr_0.1Mn_0.3Fe_0.2^2 + )_Σ4.0 [ Si_2O_7]_2O_3( F_0.3( OH)_0.4O_0.3)_Σ1.0 ⋅4.3H2O and corresponds to an intermediate member of the murmanite–calciomurmanite isomorphic series. The enthalpy of formation of the studied murmanite from elements was determined for the first time by high-temperature melt solution calorimetry on a Calvet microcalorimeter (–9788 ± 19 kJ/mol). Its standard entropy was estimated, and Gibbs energy of formation was calculated (870.4 J/(mol K) and –9015 ± 19 kJ/mol, respectively). The thermodynamic constants of the end-members of the murmanite–calciomurmanite isomorphic series were estimated.
The element distribution was analyzed in the surface bottom sediments of the lakes of the Kuril archipelago (Maloe and Pernatoe lakes), Magadan district (Grand, Chernoe, Chistoe, Bezymyanka, Chukcha, Ui, and Forel lakes), and Chukotka (Lake Elgygytgyn). The distribution of TiO2, SiO2/TiO2, Al2O3/TiO2, and Fe2O3/TiO2 in the sediments of the lakes depends on the size of deluvium fractions and composition of bedrocks and reflect sedimentation conditions. The SiO2/TiO2 ratio and the SiO2 content show simultaneous variations throughout cores, which are indicative of biogenic silica accumulation and productivity of basins. The Al2O3/TiO2 ratio is an indicator of grain-size composition, with lower values for fine sediments. The peaks of Fe2O3/TiO2 and TiO2 values are in some cases an indicator of chemogenic iron accumulation. These levels may indicate the presence of autigenic iron-bearing minerals.
This paper presents data on the pigment composition, organic carbon (Corg) content, and molecular composition of n-alkanes in the bottom sediments and adjacent soils of streams in Voronezh Heights (Khabarovsk). The Corg (1.85–25.34
The paper presents data on a representative collection of rocks from the Guli Massif, the largest alkaline-ultramafic carbonatite intrusion of the Maimecha–Kotuy Province and one of the largest worldwide. The Rb–Sr and Sm–Nd isotopic systems of rocks of the various intrusive phases of the pluton were analyzed by TIMS. The samples represented a wide spectrum of rocks from olivinites and melteigite–ijolites to melanephelinites and carbonatites. The Sr and Nd initial isotopic compositions of rocks of the Guli Massif suggest that their parental melts were derived from a mantle source moderately enriched relative to the convecting mantle. These enriched isotopic signatures suggest that the source of the parental melts contained an enriched component. At the same time, the Sr and Nd isotopic ratios of the rocks display narrow variation ranges : (87Sr/86Sr)0 = 0.7031–0.7038 and εNd(250) = +3.9 to +5.4 and no systematic changes from earlier to later intrusive phases. This likely reflects the isotopic homogeneity of the magma source and a minimal contamination by the host rocks. Comparison of our data on the Guli Massif with those on other alkaline–carbonatite intrusions worldwide seems to point to relationships between the size of a magmatic body and the degree of isotopic heterogeneity of its rocks. The Guli Massif and the Khibiny and Lovozero complexes are the world’s largest alkaline-carbonatite intrusions and show the smallest dispersion of their Sr and Nd isotopic ratios, whereas smaller intrusions display a significantly wider scatter of isotopic characteristics of their rocks. It is proposed that the large magma volumes of the larger massifs maintained the stability of their composition and limited the effects of contamination on their isotopic systems.
A comprehensive geochemical assessment of heavy metal and arsenic contamination in the bottom sediments of the “small rivers of urbanized territories–Kaliningrad Sea Channel–Kaliningrad Bay” system was conducted. Using X-ray fluorescence and atomic absorption analysis, the bulk concentrations of Zn, Cu, Pb, Ni, Cr, Cd, Hg, and As as well as additional elements (Mn, Co, V, and Sr) were determined in 13 samples from the watercourses of Kaliningrad and Svetlogorsk, and in 9 samples from the channel water area. The geochemical accumulation indices Igeo, PI, PLI, NPI, and PERI were calculated, and the results were compared with the clarke values and ERL/ERM thresholds. It was found that the small watercourses contain local anomalies of Zn, Cu, Pb, and Cr, which are confined to the discharge of industrial and stormwater wastewater (NPI up to 11.7; PLI > 1). In the bottom sediments of the Kaliningrad Sea Channel, the Igeo values were negative (<0), which correspond to the background level, and PERI at all stations is below 90, indicating a low environmental risk. Some Cd exceedances were recorded in the port waters of Svetly. The results obtained justify the need for priority monitoring of estuaries of small rivers and areas of port infrastructure.
An Erratum to this paper has been published: https://doi.org/10.1134/S001670292629001X
Asphaltenes, resins, and acids from immature oil were subjected to thermolysis, and the distribution patterns of hydrocarbon biomarkers (HC biomarkers) C15 sesquiterpanes were then studied. It was shown that both the original oil and the thermolysis products of high-molecular-weight hydrocarbon (HC) precursors of the oil contain all seven isomers of C15 sesquiterpanes, which usually occur in mature oils, but the relative distributions of C15 sesquiterpane isomers are different. The relative content of 1,2,3,7,7-pentamethylbicyclo[4,4,0]decane (drimane) in the thermolysis products of high-molecular-weight petroleum hydrocarbon precursors is significantly higher than in the original immature crude oil. This means that drimane, like normal alkanes, is released from high-molecular-weight precursors under more severe conditions. The relative content of drimane in oil may perhaps be indicative of the maturity of the oil.
An Erratum to this paper has been published: https://doi.org/10.1134/S0016702926290021
Information on the depth and age of sedimentary layers in the deepest 50-km north–south segment of a seismic profile across the North Caspian Basin is used to develop a simplified model for the formation of the salt folds. The model is applied to numerically assess how the development of the salt structure affected the temperature and generation history of the sub- and supra-salt sedimentary complexes in this basin. Calculations demonstrate significant differences in the maturity of organic matter (OM) and hydrocarbon (HC) generation between rocks of the same age in the axial and marginal zones of the salt structures. These differences also depended on the duration of the growth of the salt structures. For example, in the model of the slow formation of the salt folds (from 268 to 23 Ma), rocks at the top of the sub-salt sedimentary complex in the marginal zone of the salt structure had fully converted their hydrocarbon generation potential in the Cretaceous, while rocks of the same age in the axial zones of the structures retain a significant portion of their liquid hydrocarbon generation potential until nowadays. The situation is opposite in the model of the rapid growth of the salt folds (from 268 to 251 Ma). In this model, the temperature and OM maturity of rocks in the sub-salt complex in the axial zones of the folds might have been comparable to or even higher than the values of these parameters in the marginal zones of the structures. Lateral heat transfer in the calculations of the temperature field on the flanks of salt-bearing structures leads to lower estimates of the temperatures and maturity of the rocks compared to their values in flat basin modeling systems that do not account for lateral heat transfer. Conversely, in the calculations for axial zones of salt structures, lateral heat transfer increases the temperature and maturity.
The synthesis of primary organic molecules capable of self-organization into autocatalytic geochemical networks was a necessary step preceding the formation of metabolic structures of nascent life. This paper presents a thermodynamic justification for the possible involvement of deep mantle non-methane hydrocarbons (HC) in the formation and replenishment of intermediate molecules of chemoautotrophic metabolism during its early emergence stages. The results demonstrate that the interaction of the hydrocarbon system (C–H) with oxygen from oxidative mineral buffers under hydrothermal conditions can lead to its transformation into an oxygen-containing system (C–H–O) represented by key metabolic intermediates. Metastable equilibrium assemblages between these systems and HC represented in the temperature diagrams of the chemical potentials of oxygen and hydrogen are considered as a hypothetical model for the initial stage of protometabolic network formation. The key advantage of the proposed prebiotic synthesis is the absence of water (H2O) among the reactants and products of reactions occurring in an aqueous environment.
The geochemical features of REE distribution in the soil–plant system in the impact zone of apatite–nepheline ore mining and processing enterprises of the Kola Peninsula were studied. Samples of podzolic and wetland soils, plants (birch leaves (Betula subarctica) and sphagnum moss (Sphagnum L.)) affected by mining and processing activity at the Khibiny alkaline massif, and atmospheric aerosols (main transport medium) were investigated. Rare earth elements were analyzed in plants, soils, and aerosols by inductively coupled plasma mass spectrometry. The contents of REE in soils, birch leaves, and moss affected by mining and processing operations on the apatite–nepheline ores of the Kola Peninsula are reported. It was shown that the soils are characterized by salt extraction pH values from 3.23 to 7.31, and there is a moderate correlation between the total REE content in the soils and the pH of salt extraction (r = 0.40, p < 0.001). Data on REE content in atmospheric air in the cities of Kirovsk and Apatity were obtained for the first time. The total concentrations of REE in the birch leaves and mosses were found to exceed the reference plant value by factors of 4.4 and 185, respectively, which indicates the outstanding role of moss as a bioindicator and superaccumulator. The highest REE contents accompanied by high phosphorus, fluorine, and strontium are typical of sites located in the immediate vicinity of railway tracks. It was established that an increase in the La/Yb ratio is an indicator of soil contamination with apatite ore dust, which is a new diagnostic criterion for monitoring the environmental impact of mining and processing facilities. The calculated biological concentration factors decreased in the La–Lu sequence for both plant species. It was found that the Eu biological concentration factor of the birch leaves was significantly higher than those of neighboring REE. It was shown for the first time that selective Eu accumulation occurs in the soil–birch leaf system, which results in a factor 2–10 increase in the Eu anomaly in the birch leaves relative to the soil. In contrast, Eu fractionation does not occur in the source rock–soil–moss system.
This paper presents the results of lithogeochemical studies of volcanogenic-terrigenous deposits in the Bagdarin Subzone of the Vitimkan–Tsipa Zone (Baikal–Vitim Fold System). Facies analysis confirms shallow-water sedimentation conditions. The deposits in the Bagdarin Subzone are predominantly of graywacke composition. Lithogeochemical data indicate a mixed provenance: island-arc volcanic complexes played a major role, with an additional contribution from rocks of the Precambrian continental basement. Terrigenous rocks from the Tocher and Orocha types of section in the Bagdarin Subzone have identical lithogeochemical characteristics, suggesting sediment accumulation in a single paleobasin. The weathering crust of the Orocha Formation formed in an arid to semi-arid climate, and the rocks acquired specific geochemical features, such as the complete leaching of sodium and high degree of REE fractionation. Sediment accumulation of the Bagdarin and Tocher formations occurred in a back-arc basin due to the erosion of proximal volcanic arcs and outcrops of the Precambrian basement that underwent intense chemical weathering.
Source rock from the Huoshiling Formation in the southern Songliao Basin is of particular significance, as it is a critical contributor of deep layer natural gas, which has become one of the exploration targets in this region. However, knowledge of its geochemical characteristics is largely limited, which is further insufficient to address the substantial heterogeneity of different sub-sags which are separated by faults during the rifting stage. In this study, we conduct organic geochemical analysis using gas chromatography-mass spectrometry (GC-MS) of Huoshiling Formation source rock retrieved from sub-sags namely Baojia, Guojia, Huajia, Lanjia and Nong’an South in Dehui fault depression and Xiaochengzi sub-sag in Wangfu fault depression, southern Songliao Basin. The results obtained demonstrate that the biomarker of source rock displays substantial variation, particularly in the distribution of n-alkanes, steranes and hopanes, indicating organic matter originating from different sources in the sub-sags. Combining bulk geochemical data, we propose that source rock in Dehui and Wangfu fault depression could be classified into three categories, each exhibiting a comparatively elevated proportion of organic matter derived from algae, terrestrial plants and bacteria, respectively. This is found to be intimately linked to the source rock quality. Particularly, Nong’an South sub-sag is characterized by elevated levels of both the sterane/hopane ratio and the C27 sterane percentage, indicative of remarkable algae input which results in better quality of higher hydrocarbon generation potential and saturated hydrocarbons when compared to other studied sub-sags. This provides valuable insight into the exploration of the deep layer in the southern Songliao Basin.
The Baihua’ao fluorite deposit is a typical fluorite deposit in central Hunan Province and is closely associated with granite. This paper conducted whole-rock geochemical, zircon U–Pb isotope geochronology, and zircon Hf isotope geochemical tests on the Yanshanian granite in the surrounding rocks to elucidate the relationship between its mineralization process and magmatic activity. The U–Pb isotopic age of zircon is 151.7 ± 1.4 Ma, belonging to the Yanshanian period. The SiO2, K2O, A/CNK, and (Zr + Nb + Ce + Y)–FeOT/MgO, (Zr + Nb + Ce + Y)–(Na2O + K2O)/CaO–(Al2O3–(K2O + Na2O))–(FeOT + MgO), and SiO2 FeOT/(FeOT + MgO) indicate that the samples are classified as a peraluminous S-type granite. The Zr, Hf, FeO, MgO, and δ Eu levels suggest that the magma has experienced a certain level of crystallization fractionation. The Th, U, CaO/Na2O, Rb/Sr, Rb/Ba, εHf(t), and Al2O3 + FeO + MgO + TiO2–Al2O3/(FeO + MgO + TiO2) indicate that the source rock predominantly consists of Paleoproterozoic crust, with a minor contribution of mantle material. The comprehensive analysis of Y–Nb and Y + Nb–Rb diagrams, as well as the regional geological background, indicates that the tectonic setting is characterized by the return under the low-angle subduction of the ancient Pacific Ocean and the upwelling of mantle material. Comprehensive analysis indicates that the Baihua’ao fluorite deposit is a magmatic hydrothermal deposit, in which fluorine-containing minerals in subducting plates decompose to produce fluorine-rich fluids or magmas. Fluorine-saturated fluids ascend from the Earth’s mantle to the crust, resulting in the formation of fluorite deposits.
To constrain the tectonic setting of Late Triassic magmatism in the Luocang area, western Gangdese Belt, this study analyzes monzogabbros via zircon U–Pb dating, whole-rock geochemistry, Sr–Nd–Hf isotopic analysis, and mineral chemistry. Zircon U–Pb dating yields four age groups: 295 ± 4.9, 258.6 ± 1.8, 203.5 ± 2.7, 148.8 ± 3.5 Ma. Based on the analysis of its zircons, we conclude that its formation age is constrained to the Late Triassic (203.5 ± 2.7 Ma). The monzogabbros, classified as shoshonitic-series metaluminous basic rocks, exhibit geochemical characteristics of continental margin arcs – enrichment in LILEs and depletion in HFSEs, with total REEs of 188–197 ppm and no significant Eu anomaly. Isotopically, they have (87Sr/86Sr)ᵢ = 0.70394–0.70400, εNd(t) = +2.8…+3.1, and zircon εHf(t) = +6.9…+13.7, indicating a metasomatized depleted mantle wedge, modified by subducted sediment-derived melts and slab-derived melts.Mineralogically, Studies on amphiboles from the Late Triassic monzogabbros in the western Gangdese Belt indicate that they are similar in properties to the basic rocks in the eastern Gangdese Belt, both derived from magmas with relatively high oxygen fugacity and water content. Geochemical and mineralogical data confirm that the parental magma of monzogabbro was derived from partial melting of the metasomatized mantle wedge, and the monzogabbro formed by fractional crystallization of the parental magma. In addition, the magmas assimilated a certain amount of juvenile lower crustal materials during their ascent.
The diabase dykes are sparsely distributed in the Aqishan-Yamansu belt of eastern Tianshan and have received little attention. This paper reports the petrography, geochronology, and geochemistry of the Jingxia diabase dykes to provide important information for understanding tectonic evolution of eastern Tianshan. The geochemical characteristics reveal that Jingxia diabase dykes have low SiO2, medium K2O, MgO, and high Na2O. They are calc-alkaline basaltic rocks. The U–Pb SHRIMP age of magmatic zircon from the Jingxia diabase dyke in Aqishan-Yamansu belt of Eastern Tianshan Orogenic Belt is 347 ± 6 Ma, indicating that the diabase formed in the early Carboniferous. The Jingxia diabase dykes are enriched in LREEs relative to the HREEs with depletion of Nb, Ta, Zr, and Ti, which indicates that they crystallized from the melt derived from mantle source and experienced fractional crystallization and crustal contamination. The mantle source had undergone metasomatism induced by the fluid released from the subduction slab. Combined with previous studies, we propose that the Jingxia diabase dykes formed in an immature island arc setting and they were products of southward subduction of Paleo-Kangguer oceanic slab in the early Carboniferous.
This study focuses on the Permian strata and volcanic rocks in the Ondor Sum area, Inner Mongolia. By integrating zircon U–Pb geochronology, whole-rock geochemistry, and paleontological analysis, we constrain their formation age, provenance characteristics, and depositional environment, aiming to elucidate the Permian to Early Triassic tectonic evolution along the southern margin of the central Xing–Meng Orogenic Belt (XMOB). The meta–basalts of the Ondor Sum Group exhibit geochemical signatures consistent with an OIB source, including enrichment in LILEs (Rb, Ba, K, Sr), moderate enrichment in HFSEs (Nb, Ta, Zr), and the absence of a Nb–Ta negative anomaly. These features collectively indicate derivation from an enriched deep mantle source, possibly related to a mantle plume. The protolith was emplaced during the Late Permian. Detrital zircon data from sericite–bearing quartz schist within the group yield a maximum depositional age of 244 Ma. The lower part of the Amushan Formation yields a maximum depositional age of 411 Ma, while the upper part is dated at 252 Ma, indicating a substantial time gap between the two units. Combined with fossil assemblages and zircon provenance analysis, the unit is interpreted to have been deposited in a back–arc basin setting during the Late Carboniferous to Early Permian under a convergent plate regime. Integrating regional magmatic and sedimentary records, the Permian–Early Triassic tectonic evolution of the southern margin of the XMOB can be subdivided into three stages: (1) Early Permian (∼285 Ma), characterized by the development of typical calc-alkaline island arc volcanics and crustal thickening, marking the continued subduction of the Paleo-Asian Ocean (PAO); (2) Middle Permian (285–260 Ma), when slab break-off induced a shift in the magma source from juvenile arc crust to older basement, leading to peak crustal thickness and transition from subduction to collision; (3) Late Permian to Early Triassic (260–240 Ma), characterized by a post-collisional extensional regime evidenced by A–type granites, intraplate basalts, and crustal thinning. This extensional onset at 260 Ma marks the termination of collision, constraining final closure of the PAO to the Early Triassic. This study, by integrating previous research, reconstructs the spatiotemporal pattern of PAO closure and provides new constraints on the tectonic evolution of the XMOB.
Early Paleozoic leucogranites are rare in SE China, and their petrogenesis remains controversial. Here we present zircon U–Pb ages, Lu–Hf isotopes and whole-rock geochemical data for the Tangwan leucogranite in the Wuyi region of the Cathaysia Block to constrain its origin and geodynamic setting. The Tangwan leucogranite was emplaced at approximately 438 Ma. The relatively high Nb/Ta (8.39–9.32), Zr/Hf (28.6–31.8), K/Rb (130–247) and Eu/Eu* ratios (0.47–0.68), together with low TE1,3 values (0.97–1.04), indicate that the Tangwan leucogranite is not a highly fractionated granite. The low Zr + Nb + Ce +Y contents (<200 ppm) and Ga/Al ratios (<2.5) but high A/CNK ratios (>1.2), the presence of muscovite and the absence of mafic melanocratic minerals collectively point to an S-type affinity. The enriched Nd–Hf isotopic compositions, relatively high Rb/Sr ratios (>2), moderate TLREE and TZr values (699–794°C), and low TiO2 contents (<0.2 wt
