Pub Date : 2024-07-11DOI: 10.1134/s0016702924700253
E. N. Kozlov, E. N. Fomina, V. N. Reutsky, M. Yu. Sidorov
Abstract
This study presents the sulfur isotopic characteristics in baryte from carbonatites of the Sallanlatva massif and sulfides (mainly pyrite and pyrrhotite) from carbonatites, phoscorites and products of their contact interaction with the host silicate rocks of most carbonatite-bearing complexes of the Devonian Kola Alkaline Province (KAP). For some complexes (Ozernaya Varaka, Kontozero), these characteristics are reported for the first time. The determined range of δ34S variations of sulfides in one complex does not exceed 4‰, but reaches 20‰ for the entire Kola Alkaline Province. This may be related to the evolution style of carbonatites and associated rocks. It is shown that the δ34S value in sulfides decreases from (1) the least evolved volcanic carbonatites of the Kontozero complex (δ34Savg. = –1.3‰) through (2) carbonatites and phoscorites of the Kovdor, Ozernaya Varaka, Sokli, and Salmagora massifs towards (3) the rocks of Seblyavr, Vuoriyarvi, and, finally, the carbonatites of Sallanlatva (δ34Savg. = –14.7‰) massifs, where sulfides differ from those of other KAP carbonatites in their exceptionally low δ34S values. The carbonatite volcanics of Kontozero are almost barren of REE mineralization; carbonatites of the second group contain accessory amounts of REE minerals; the third group is peculiar in the abundance of late carbonatites, where REE carbonates are frequently major minerals. Thus, the greater the volume of REE minerals in carbonatites of the complex, the lower the δ34S value in sulfides from its carbonatites and associated rocks. For the first time in the KAP, the sulfur isotopic composition of associated baryte–pyrite pairs was studied in the Sallanlatva carbonatites. The sulfur isotopic characteristics are shown to correspond to the final low-temperature (250–350°C) stage of carbonatite evolution in oxidized conditions, which satisfies the parameters of baryte crystallization. Since the studied samples of the Sallanlatva carbonatites are explosive breccias, the oxidized composition of fluids may indicate their phreatomagmatic nature, i.e., formation due to the interaction of intruded hot matter (melt/fluid) with meteoric waters.
{"title":"Sulfur Isotopic Composition of Sulfides and Sulfates from Rocks of Carbonatite Complexes of the Devonian Kola Alkaline Province","authors":"E. N. Kozlov, E. N. Fomina, V. N. Reutsky, M. Yu. Sidorov","doi":"10.1134/s0016702924700253","DOIUrl":"https://doi.org/10.1134/s0016702924700253","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This study presents the sulfur isotopic characteristics in baryte from carbonatites of the Sallanlatva massif and sulfides (mainly pyrite and pyrrhotite) from carbonatites, phoscorites and products of their contact interaction with the host silicate rocks of most carbonatite-bearing complexes of the Devonian Kola Alkaline Province (KAP). For some complexes (Ozernaya Varaka, Kontozero), these characteristics are reported for the first time. The determined range of δ<sup>34</sup>S variations of sulfides in one complex does not exceed 4‰, but reaches 20‰ for the entire Kola Alkaline Province. This may be related to the evolution style of carbonatites and associated rocks. It is shown that the δ<sup>34</sup>S value in sulfides decreases from (1) the least evolved volcanic carbonatites of the Kontozero complex (δ<sup>34</sup>S<sub>avg.</sub> = –1.3‰) through (2) carbonatites and phoscorites of the Kovdor, Ozernaya Varaka, Sokli, and Salmagora massifs towards (3) the rocks of Seblyavr, Vuoriyarvi, and, finally, the carbonatites of Sallanlatva (δ<sup>34</sup>S<sub>avg.</sub> = –14.7‰) massifs, where sulfides differ from those of other KAP carbonatites in their exceptionally low δ<sup>34</sup>S values. The carbonatite volcanics of Kontozero are almost barren of REE mineralization; carbonatites of the second group contain accessory amounts of REE minerals; the third group is peculiar in the abundance of late carbonatites, where REE carbonates are frequently major minerals. Thus, the greater the volume of REE minerals in carbonatites of the complex, the lower the δ<sup>34</sup>S value in sulfides from its carbonatites and associated rocks. For the first time in the KAP, the sulfur isotopic composition of associated baryte–pyrite pairs was studied in the Sallanlatva carbonatites. The sulfur isotopic characteristics are shown to correspond to the final low-temperature (250–350°C) stage of carbonatite evolution in oxidized conditions, which satisfies the parameters of baryte crystallization. Since the studied samples of the Sallanlatva carbonatites are explosive breccias, the oxidized composition of fluids may indicate their phreatomagmatic nature, i.e., formation due to the interaction of intruded hot matter (melt/fluid) with meteoric waters.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1134/s0016702924700472
Kamaal Parvez, M. E. A. Mondal, Iftikhar Ahmad, Waliur Rahaman, Anil D. Shukla, Wamiq Mohammed Khan
Abstract
The present study focuses on the petrographic studies, XRD patterns, whole-rock geochemical data and Nd isotopic data of the clastic rocks of the Paleoproterozoic Mahakoshal Basin which includes meta-argillites, meta-greywackes and quartzites to characterize their provenance, tectonic setting, weathering intensity, and paleoclimate condition. Geochemically, the rock samples of meta-argillite and meta-greywacke in the bivariate plot Log Na2O/K2O vs. Log SiO2/Al2O3 are classified as litharenite and greywacke. The samples of quartzite fall in the fields from the sublitharenite to quartzarenite. The weathering indices such as CIA, (alpha _{{{text{Ca}}}}^{{{text{Al}}}}), (alpha _{{{text{Na}}}}^{{{text{Al}}}}), (alpha _{{text{K}}}^{{{text{Al}}}}), (alpha _{{{text{Sr}}}}^{{{text{Al}}}}), (alpha _{{{text{Ba}}}}^{{{text{Al}}}}) and Th/U suggest that the clastic rocks have undergone moderate to intense chemical weathering and show K-metasomatism. Chondrite normalized REE patterns, discriminant diagrams of La–Th–Sc and Ni–V–10*Th and various transition elements ratio such as Cr/Th, Th/Co, Th/Sc, and La/Sc support the mixing of the mafic, intermediate and felsic sources. The Eu anomaly is highly variable and ranges from 0.29 to 1.08 and supports that the sediments have been derived from the heterogeneous source. TCHUR model ages are consistent with 1.98–2.92 Ga possible provenance. εNd(t) and f(Sm/Nd) values overlap with the arc and the Archean crust signatures indicating that the sediments are derived from a Paleoproterozoic arc and older Archean crust (TTG gneisses and Archean granite). The opening of the Mahakoshal Basin is characterized by the retreating accretionary orogen and the closure of the basin is due to switching retreating accretionary orogen into advancing accretionary orogen which is contemporaneous to the assembly of the Columbia Supercontinent (∼1.8 Ga).
{"title":"Mineralogical, Geochemical and Nd Isotopic Study of the Meta-Clastic Rocks of the Paleoproterozoic Mahakoshal Basin, Central Indian Tectonic Zone: Implications for Provenance Characterization, Paleoweathering Conditions and Tectonic Setting","authors":"Kamaal Parvez, M. E. A. Mondal, Iftikhar Ahmad, Waliur Rahaman, Anil D. Shukla, Wamiq Mohammed Khan","doi":"10.1134/s0016702924700472","DOIUrl":"https://doi.org/10.1134/s0016702924700472","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The present study focuses on the petrographic studies, XRD patterns, whole-rock geochemical data and Nd isotopic data of the clastic rocks of the Paleoproterozoic Mahakoshal Basin which includes meta-argillites, meta-greywackes and quartzites to characterize their provenance, tectonic setting, weathering intensity, and paleoclimate condition. Geochemically, the rock samples of meta-argillite and meta-greywacke in the bivariate plot Log Na<sub>2</sub>O/K<sub>2</sub>O vs. Log SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> are classified as litharenite and greywacke. The samples of quartzite fall in the fields from the sublitharenite to quartzarenite. The weathering indices such as CIA, <span>(alpha _{{{text{Ca}}}}^{{{text{Al}}}})</span>, <span>(alpha _{{{text{Na}}}}^{{{text{Al}}}})</span>, <span>(alpha _{{text{K}}}^{{{text{Al}}}})</span>, <span>(alpha _{{{text{Sr}}}}^{{{text{Al}}}})</span>, <span>(alpha _{{{text{Ba}}}}^{{{text{Al}}}})</span> and Th/U suggest that the clastic rocks have undergone moderate to intense chemical weathering and show K-metasomatism. Chondrite normalized REE patterns, discriminant diagrams of La–Th–Sc and Ni–V–10*Th and various transition elements ratio such as Cr/Th, Th/Co, Th/Sc, and La/Sc support the mixing of the mafic, intermediate and felsic sources. The Eu anomaly is highly variable and ranges from 0.29 to 1.08 and supports that the sediments have been derived from the heterogeneous source. T<sub>CHUR</sub> model ages are consistent with 1.98–2.92 Ga possible provenance. εNd(t) and <i>f</i>(Sm/Nd) values overlap with the arc and the Archean crust signatures indicating that the sediments are derived from a Paleoproterozoic arc and older Archean crust (TTG gneisses and Archean granite). The opening of the Mahakoshal Basin is characterized by the retreating accretionary orogen and the closure of the basin is due to switching retreating accretionary orogen into advancing accretionary orogen which is contemporaneous to the assembly of the Columbia Supercontinent (∼1.8 Ga).</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1134/s0016702924700460
M. Ait Mechedal, H. Laoufi, K. Ouamer-ali, K. Djili, Y. Daoud, D. B. Sims
Abstract
Knowledge of the geochemistry of selenium (Se) is crucial for understanding its behavior in the environment. While numerous studies have explored selenium geochemistry, there is a notable inadequacy, especially in extreme soil conditions such as saline soils, which are widespread globally. This study focuses on characterizing the geochemistry of selenium in saline soils, with a specific focus on the El Hamadna perimeter in Bas-Cheliff, Algeria. This location was chosen due to its diverse salinity levels and selenium content. Utilizing Phreeqc software, the study examines selenium’s chemical speciation. In the arid soils of this region, predicted selenium (IV) concentrations range from 0.19 to 3.05 mg kg–1, and selenium (VI) concentrations range from 0.54 to 5.58 mg kg–1. A significant negative correlation was observed between total selenium and Se(VI) concentrations with pH, whereas Se(IV) showed a positive and significant correlation with pH. No correlation was found between selenium concentrations and the salinity gradient in the studied soils. Non-significant correlations were observed between selenium levels and CaCO3, clay, and organic matter in the soils, suggesting that these soil properties do not influence the distribution of selenium concentrations in the examined soils. Only the pH and the presence of the main form MgSeO3 control the representation of selenium in the soil profile.
{"title":"Studying the Influence of Soil Characteristics on Selenium Distribution in Bas-Chellif Soils Algeria and Predicting Speciation Patterns","authors":"M. Ait Mechedal, H. Laoufi, K. Ouamer-ali, K. Djili, Y. Daoud, D. B. Sims","doi":"10.1134/s0016702924700460","DOIUrl":"https://doi.org/10.1134/s0016702924700460","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Knowledge of the geochemistry of selenium (Se) is crucial for understanding its behavior in the environment. While numerous studies have explored selenium geochemistry, there is a notable inadequacy, especially in extreme soil conditions such as saline soils, which are widespread globally. This study focuses on characterizing the geochemistry of selenium in saline soils, with a specific focus on the El Hamadna perimeter in Bas-Cheliff, Algeria. This location was chosen due to its diverse salinity levels and selenium content. Utilizing Phreeqc software, the study examines selenium’s chemical speciation. In the arid soils of this region, predicted selenium (IV) concentrations range from 0.19 to 3.05 mg kg<sup>–1</sup>, and selenium (VI) concentrations range from 0.54 to 5.58 mg kg<sup>–1</sup>. A significant negative correlation was observed between total selenium and Se(VI) concentrations with pH, whereas Se(IV) showed a positive and significant correlation with pH. No correlation was found between selenium concentrations and the salinity gradient in the studied soils. Non-significant correlations were observed between selenium levels and CaCO<sub>3</sub>, clay, and organic matter in the soils, suggesting that these soil properties do not influence the distribution of selenium concentrations in the examined soils. Only the pH and the presence of the main form MgSeO<sub>3</sub> control the representation of selenium in the soil profile.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-29DOI: 10.1134/s001670292470037x
V. D. Strakhovenko, E. A. Ovdina, G. I. Malov, V. I. Malov
Abstract
The contemporary scientific investigations delves into the mechanisms of migration, distribution, and fractionation of rare earth elements and yttrium (REE + Y) in aqueous environments characterized by humid and arid sedimentogenesis. This particular facet has been employed to solve numerous fundamental inquiries pertaining to lithology and paleolimnology. The manner in which REE + Y behave in water bodies within the cryolithozone remains largely unexplored. By evaluating the concentration levels and distribution patterns of REE + Y in the waters and sediments of the lakes situated in the Ukok Plateau and the Ulagan depression, under the prevailing conditions of cryolithogenesis as the primary geochemical process transforming rocks, soils, and sediments, we were able to augment the existing comprehension of nival sedimentation. In all the lakes examined, the content of REE + Y in the water exhibits a similar magnitude as that of small lakes in other landscape zones of the southern Western Siberia, while the content level of REE + Y is greater in the bottom sediments. The concentrations, distribution and fractionation of REE + Y vary from lake to lake and are determined by several factors: the chemical properties of REE + Y in solutions, the intensity of transformation of host rocks and the mineral forms of the REE + Y in the rocks (minerals). The concentrations, distribution and fractionation of REE + Y in bottom sediments vary slightly from lake to lake except for the contents of Eu, Y, La. The content of Eu, Y, La in the bottom sediment of the lake is influenced by a combination of factors, including their concentrations in the water, the redox conditions of diagenesis, and the mineral composition of the bottom sediment, particularly the amount of accessory minerals.
摘要当代科学研究深入探讨了稀土元素和钇（REE + Y）在以潮湿和干旱沉积为特征的水环境中的迁移、分布和分馏机制。这一特殊方面已被用于解决与岩石学和古气候学有关的许多基本问题。REE + Y 在冰冻带水体中的行为方式在很大程度上仍未得到探索。通过评估位于乌科克高原和乌拉干洼地的湖泊水体和沉积物中 REE + Y 的浓度水平和分布模式，我们能够在低温成岩作用（岩石、土壤和沉积物的主要地球化学过程）普遍存在的条件下，加深对新沉积作用的理解。在所有考察的湖泊中，水中的 REE + Y 含量与西西伯利亚南部其他地貌区的小湖泊相似，而底部沉积物中的 REE + Y 含量更高。REE + Y 的浓度、分布和分馏因湖而异，并由以下几个因素决定：溶液中 REE + Y 的化学特性、寄主岩石的转化强度以及岩石（矿物）中 REE + Y 的矿物形态。除 Eu、Y、La 的含量外，底层沉积物中 REE + Y 的浓度、分布和分馏在不同湖泊中略有不同。湖底沉积物中 Eu、Y、La 的含量受多种因素的影响，包括它们在水中的浓度、成岩过程中的氧化还原条件以及底层沉积物的矿物组成，尤其是附属矿物的含量。
{"title":"REE Distribution in the Water and Bottom Sediments of Small Lakes within the Ukok Plateau and the Ulagan Depression (Russian Altai)","authors":"V. D. Strakhovenko, E. A. Ovdina, G. I. Malov, V. I. Malov","doi":"10.1134/s001670292470037x","DOIUrl":"https://doi.org/10.1134/s001670292470037x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The contemporary scientific investigations delves into the mechanisms of migration, distribution, and fractionation of rare earth elements and yttrium (REE + Y) in aqueous environments characterized by humid and arid sedimentogenesis. This particular facet has been employed to solve numerous fundamental inquiries pertaining to lithology and paleolimnology. The manner in which REE + Y behave in water bodies within the cryolithozone remains largely unexplored. By evaluating the concentration levels and distribution patterns of REE + Y in the waters and sediments of the lakes situated in the Ukok Plateau and the Ulagan depression, under the prevailing conditions of cryolithogenesis as the primary geochemical process transforming rocks, soils, and sediments, we were able to augment the existing comprehension of nival sedimentation. In all the lakes examined, the content of REE + Y in the water exhibits a similar magnitude as that of small lakes in other landscape zones of the southern Western Siberia, while the content level of REE + Y is greater in the bottom sediments. The concentrations, distribution and fractionation of REE + Y vary from lake to lake and are determined by several factors: the chemical properties of REE + Y in solutions, the intensity of transformation of host rocks and the mineral forms of the REE + Y in the rocks (minerals). The concentrations, distribution and fractionation of REE + Y in bottom sediments vary slightly from lake to lake except for the contents of Eu, Y, La. The content of Eu, Y, La in the bottom sediment of the lake is influenced by a combination of factors, including their concentrations in the water, the redox conditions of diagenesis, and the mineral composition of the bottom sediment, particularly the amount of accessory minerals.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The East Qinling Molybdenum Belt (EQMB), which is located on the southern margin of the North China Craton (NCC), is the largest Mo province in the world. This belt hosts a significant number of Mesozoic magmatic-hydrothermal Mo deposits and a small portion of pre-Mesozoic Mo deposits. Understanding the mineralization timing and mechanism of the unique pre-Mesozoic Mo deposits is essential to comprehend the evolution of the EQMB, the pre-Mesozoic Mo enrichment, and the Mesozoic Mo mineralization event. The recently discovered Zhaiwa deposit is a porphyry Mo deposit located in the Xiong’er Terrane of the EQMB. In this study, five molybdenite samples from the Mo-bearing quartz veins were analyzed for Re-Os isotopes composition. These samples yield an isochron age of 1794 ± 45 Ma, which represents the age of mineralization. The mineralization is mostly hosted within the biotite-amphibole plagiogneiss and granite porphyry. LA-ICP-MS U-Pb data of zircons constrain the crystallization age of the granite porphyry to be at 1791 ± 16 Ma. The close spatial and temporal association suggests that the granite porphyry is the causative rocks of the Mo mineralization. The δ34S values of pyrite vary from 5.3 to 6.8‰, suggesting that the S was mainly derived from magmatic source. The intrusion of magmas and associated Mo mineralization are contemporaneous to the regional Xiong’er volcanism that occurred during the late Paleoproterozoic. The Xiong’er volcanism was triggered by partial melting of lithospheric mantle in an extensional setting. The results of our study provide robust evidence for a late Paleoproterozoic Mo metallogenic event along the southern margin of the NCC. Future exploration should also consider the potential of late Paleoproterozoic porphyry Mo mineralization existing in the EQMB, which is closely associated with the Xiong’er volcanism.
{"title":"The Timing and Genesis of Late Paleoproterozoic Molybdenum Mineralization in the East Qinling Molybdenum Belt, China: Constraints from the Zhaiwa Deposit","authors":"Bing Yu, Qingdong Zeng, Shuai Gao, Jianling Xue, Xiaofei Zhang","doi":"10.1134/s0016702924700381","DOIUrl":"https://doi.org/10.1134/s0016702924700381","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The East Qinling Molybdenum Belt (EQMB), which is located on the southern margin of the North China Craton (NCC), is the largest Mo province in the world. This belt hosts a significant number of Mesozoic magmatic-hydrothermal Mo deposits and a small portion of pre-Mesozoic Mo deposits. Understanding the mineralization timing and mechanism of the unique pre-Mesozoic Mo deposits is essential to comprehend the evolution of the EQMB, the pre-Mesozoic Mo enrichment, and the Mesozoic Mo mineralization event. The recently discovered Zhaiwa deposit is a porphyry Mo deposit located in the Xiong’er Terrane of the EQMB. In this study, five molybdenite samples from the Mo-bearing quartz veins were analyzed for Re-Os isotopes composition. These samples yield an isochron age of 1794 ± 45 Ma, which represents the age of mineralization. The mineralization is mostly hosted within the biotite-amphibole plagiogneiss and granite porphyry. LA-ICP-MS U-Pb data of zircons constrain the crystallization age of the granite porphyry to be at 1791 ± 16 Ma. The close spatial and temporal association suggests that the granite porphyry is the causative rocks of the Mo mineralization. The δ<sup>34</sup>S values of pyrite vary from 5.3 to 6.8‰, suggesting that the S was mainly derived from magmatic source. The intrusion of magmas and associated Mo mineralization are contemporaneous to the regional Xiong’er volcanism that occurred during the late Paleoproterozoic. The Xiong’er volcanism was triggered by partial melting of lithospheric mantle in an extensional setting. The results of our study provide robust evidence for a late Paleoproterozoic Mo metallogenic event along the southern margin of the NCC. Future exploration should also consider the potential of late Paleoproterozoic porphyry Mo mineralization existing in the EQMB, which is closely associated with the Xiong’er volcanism.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141198398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1134/s0016702923700179
M. I. Vasilevich, N. S. Smirnov
Abstract—
The layer-by-layer analysis of the variation dynamics of chemical parameters of snow at one of the observation sites (at the village of Yaksha) in the Pechora–Ilych state biosphere reserve in the winter of 2019–2020 has shown that the chemical composition of atmospheric precipitation is affected dominantly by long-range material transport. Features of the atmospheric circulation and the regions from which air masses are transferred control the saturation of the precipitation with certain chemical components. The calculation of the trajectories of reverse transport of air masses allowed us to identify regions where the air masses can be formed that come to the study area and carry material that potentially affects the chemical composition of the precipitation. The calculation of trajectories is demonstrated to make it possible to identify source regions of pollutants entering the atmosphere. This method of studying the chemical composition of snow is generally very informative and enables better understanding its formation factors.
{"title":"Effect of Atmospheric Circulation on the Seasonal Dynamics of the Chemical Composition of the Snow Cover in the Pechora–Ilych Reserve","authors":"M. I. Vasilevich, N. S. Smirnov","doi":"10.1134/s0016702923700179","DOIUrl":"https://doi.org/10.1134/s0016702923700179","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract—</h3><p>The layer-by-layer analysis of the variation dynamics of chemical parameters of snow at one of the observation sites (at the village of Yaksha) in the Pechora–Ilych state biosphere reserve in the winter of 2019–2020 has shown that the chemical composition of atmospheric precipitation is affected dominantly by long-range material transport. Features of the atmospheric circulation and the regions from which air masses are transferred control the saturation of the precipitation with certain chemical components. The calculation of the trajectories of reverse transport of air masses allowed us to identify regions where the air masses can be formed that come to the study area and carry material that potentially affects the chemical composition of the precipitation. The calculation of trajectories is demonstrated to make it possible to identify source regions of pollutants entering the atmosphere. This method of studying the chemical composition of snow is generally very informative and enables better understanding its formation factors.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1134/s0016702923700131
E. S. Persikov, P. G. Bukhtiyarov, O. Y. Shaposhnikova, L. Ya. Aranovich, A. N. Nekrasov
Abstract—
Important problems of magma differentiation, formation of native metals, and ore-forming processes in the Earth’s crust are often related to participation of hydrogen. In this paper, new experimental data on the crystallization of andesite melts at high temperatures (900–1250°C) and hydrogen pressures (10–100 MPa) have been obtained, which clarify the possible role of hydrogen in the processes occurring in andesite melts in the Earth’s crust and during volcanism under strongly reduced conditions ((f{text{O}}_{2}) = 10–17–10–18). In the crystallization experiments, it was found out that the compositions of the crystals (pyroxenes and plagioclases) formed in experiments on crystallization of andesite melt under hydrogen pressure closely correspond to the crystal compositions of lava flows of Avacha volcano in Kamchatka. This result can be considered as an experimental confirmation of the participation of hydrogen in the volcanic process.
{"title":"Andesite Melt Crystallization under Moderate Hydrogen Pressures: An Experimental Study","authors":"E. S. Persikov, P. G. Bukhtiyarov, O. Y. Shaposhnikova, L. Ya. Aranovich, A. N. Nekrasov","doi":"10.1134/s0016702923700131","DOIUrl":"https://doi.org/10.1134/s0016702923700131","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Abstract</b>—</h3><p>Important problems of magma differentiation, formation of native metals, and ore-forming processes in the Earth’s crust are often related to participation of hydrogen. In this paper, new experimental data on the crystallization of andesite melts at high temperatures (900–1250°C) and hydrogen pressures (10–100 MPa) have been obtained, which clarify the possible role of hydrogen in the processes occurring in andesite melts in the Earth’s crust and during volcanism under strongly reduced conditions (<span>(f{text{O}}_{2})</span> = 10<sup>–17</sup>–10<sup>–18</sup>). In the crystallization experiments, it was found out that the compositions of the crystals (pyroxenes and plagioclases) formed in experiments on crystallization of andesite melt under hydrogen pressure closely correspond to the crystal compositions of lava flows of Avacha volcano in Kamchatka. This result can be considered as an experimental confirmation of the participation of hydrogen in the volcanic process.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1134/s001670292370012x
E. V. Limanov, V. G. Butvina, O. G. Safonov, A. V. Spivak, K. V. Van, S. S. Vorobey
Abstract—
The paper presents data on the formation of K–Na richterite in the enstatite + diopside association with K2CO3–Na2CO3–CO2–H2O fluid at 3 GPa and 1000°C as a model for the formation of this mineral in peridotites of the upper mantle. Richterite formation depends on the (H2O + CO2)/(K2CO3 + Na2CO3) and K2CO3/Na2CO3 ratios in the starting material. A high concentration of alkaline components in the fluid leads to the decomposition of clinopyroxene, the formation of olivine, and a change in the component composition of the pyroxene and amphibole. Fluids with a high potassium concentration are favorable for the formation of K-richterite similar in composition to that formed in metasomatized peridotites of the upper mantle. In some cases, such a fluid leads to the decomposition of amphibole and stabilization of alkaline melt. An increase in the activity of the sodium component results in richterite similar in composition to richterite from lamproites. The clarified relations can be used to assess the activities of fluid components and conditions for the formation of K-richterite. To update the data bank of the Raman spectra of minerals, the largest and most homogeneous amphibole crystals of different compositions were studied.
{"title":"Formation of Richterite in the Enstatite–Diopside System in the Presence of K2CO3–Na2CO3–CO2–H2O Fluid: Implications for the Processes of Mantle Metasomatism","authors":"E. V. Limanov, V. G. Butvina, O. G. Safonov, A. V. Spivak, K. V. Van, S. S. Vorobey","doi":"10.1134/s001670292370012x","DOIUrl":"https://doi.org/10.1134/s001670292370012x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Abstract</b>—</h3><p>The paper presents data on the formation of K–Na richterite in the enstatite + diopside association with K<sub>2</sub>CO<sub>3</sub>–Na<sub>2</sub>CO<sub>3</sub>–CO<sub>2</sub>–H<sub>2</sub>O fluid at 3 GPa and 1000°C as a model for the formation of this mineral in peridotites of the upper mantle. Richterite formation depends on the (H<sub>2</sub>O + CO<sub>2</sub>)/(K<sub>2</sub>CO<sub>3</sub> + Na<sub>2</sub>CO<sub>3</sub>) and K<sub>2</sub>CO<sub>3</sub>/Na<sub>2</sub>CO<sub>3</sub> ratios in the starting material. A high concentration of alkaline components in the fluid leads to the decomposition of clinopyroxene, the formation of olivine, and a change in the component composition of the pyroxene and amphibole. Fluids with a high potassium concentration are favorable for the formation of K-richterite similar in composition to that formed in metasomatized peridotites of the upper mantle. In some cases, such a fluid leads to the decomposition of amphibole and stabilization of alkaline melt. An increase in the activity of the sodium component results in richterite similar in composition to richterite from lamproites. The clarified relations can be used to assess the activities of fluid components and conditions for the formation of K-richterite. To update the data bank of the Raman spectra of minerals, the largest and most homogeneous amphibole crystals of different compositions were studied.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1134/s0016702923700155
A. F. Redkin, N. P. Kotova, Yu. B. Shapovalov, A. N. Nekrasov
Abstract—
New data on roméite (CaNa)Sb2O6F solubility in the NaF–H2O system of P–Q type have been obtained within a wide range of sodium fluoride concentrations (from 0 to 25 wt % NaF). The concentration of antimony, in equilibrium with roméite and fluorite, in the range of NaF concentrations from 1 to 8 mol kg–1 H2O (25 wt % NaF), is in the range of 0.02–0.2 mol kg–1 H2O. According to the data, the concentration of antimony in phases L1 and L2 in the region of fluid immiscibility of the NaF–H2O system at 800°C, 200 MPa and fO2 = 50 Pa, specified by the Cu2O–CuO buffer, is 0.4 and 2.1 wt % Sb, respectively. Our experiments were the first ever to produce skeletal fluorite crystals and the intermetallic compound Pt5Sb, which belongs the hexagonal crystal system and has the following lattice parameters (LP): a = b = 4.56(4) Å, c = 4.229(2) Å, and α = β = 90°, γ = 120°. Pentaplatinum antimonide was formed on the inner surface of the Pt capsules at 800°C, Р = 200 MPa, and fO2 ≤ 10–3.47 Pa (Cu–Cu2O buffer) in experiments on the incongruent dissolution of roméite, which causes a sharp decrease (more than 1000 times) in antimony concentration in the solution.
{"title":"Roméite Solubility in the Fluid Immiscibility Region of the NaF–H2O System at 800°C, 200 MPa","authors":"A. F. Redkin, N. P. Kotova, Yu. B. Shapovalov, A. N. Nekrasov","doi":"10.1134/s0016702923700155","DOIUrl":"https://doi.org/10.1134/s0016702923700155","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract—</h3><p>New data on roméite (CaNa)Sb<sub>2</sub>O<sub>6</sub>F solubility in the NaF–H<sub>2</sub>O system of P–Q type have been obtained within a wide range of sodium fluoride concentrations (from 0 to 25 wt % NaF). The concentration of antimony, in equilibrium with roméite and fluorite, in the range of NaF concentrations from 1 to 8 mol kg<sup>–1</sup> H<sub>2</sub>O (25 wt % NaF), is in the range of 0.02–0.2 mol kg<sup>–1</sup> H<sub>2</sub>O. According to the data, the concentration of antimony in phases <i>L</i><sub>1</sub> and <i>L</i><sub>2</sub> in the region of fluid immiscibility of the NaF–H<sub>2</sub>O system at 800°C, 200 MPa and <i>f</i>O<sub>2</sub> = 50 Pa, specified by the Cu<sub>2</sub>O–CuO buffer, is 0.4 and 2.1 wt % Sb, respectively. Our experiments were the first ever to produce skeletal fluorite crystals and the intermetallic compound Pt<sub>5</sub>Sb, which belongs the hexagonal crystal system and has the following lattice parameters (LP): <i>a</i> = <i>b</i> = 4.56(4) Å, <i>c</i> = 4.229(2) Å, and α = β = 90°, γ = 120°. Pentaplatinum antimonide was formed on the inner surface of the Pt capsules at 800°C, <i>Р</i> = 200 MPa, and <i>f</i>O<sub>2</sub> ≤ 10<sup>–3.47</sup> Pa (Cu–Cu<sub>2</sub>O buffer) in experiments on the incongruent dissolution of roméite, which causes a sharp decrease (more than 1000 times) in antimony concentration in the solution.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-09DOI: 10.1134/s0016702923700106
E. D. Berezhnaya, A. V. Dubinin
Abstract
The paper considers the current state of Platinum Group Elements (PGEs) geochemistry in the ocean. The behavior of PGEs in the aquatic environment is defined by their oxidation state, the ability to change it, and complexation. The difference in chemical properties leads to PGEs fractionation in the ocean. This is their characteristic feature, along with their ultra-low contents. The paper describes the sources of PGEs supply to the ocean, PGEs behavior in the river–sea mixing zone, and their distribution in seawater. The processes of PGE accumulation in sediments, seafloor sulfides, and ferromanganese deposits of the ocean are reviewed. Possible mechanisms of PGE accumulation on ferromanganese oxyhydroxides are discussed.
{"title":"Platinum Group Element Geochemistry in the Ocean","authors":"E. D. Berezhnaya, A. V. Dubinin","doi":"10.1134/s0016702923700106","DOIUrl":"https://doi.org/10.1134/s0016702923700106","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper considers the current state of Platinum Group Elements (PGEs) geochemistry in the ocean. The behavior of PGEs in the aquatic environment is defined by their oxidation state, the ability to change it, and complexation. The difference in chemical properties leads to PGEs fractionation in the ocean. This is their characteristic feature, along with their ultra-low contents. The paper describes the sources of PGEs supply to the ocean, PGEs behavior in the river–sea mixing zone, and their distribution in seawater. The processes of PGE accumulation in sediments, seafloor sulfides, and ferromanganese deposits of the ocean are reviewed. Possible mechanisms of PGE accumulation on ferromanganese oxyhydroxides are discussed.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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