Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-49-62
G. M. Galimova, S. V. Astarkin, E. V. Gibadullina, A. Tatarintseva
Research subject. Upper Batian deposits (formation U2) of the Eastern part of the Kogalym region, within the North Nizhnevartovsk monocline. Aim. Reconstruction of the sedimentation environment of the U2 formation in the Kogalym region. Materials and methods. The reconstruction of sedimentation environments was conducted based on a macroscopic description of core samples with identification of structural and textural features of rocks from 35 wells. The clarification of sedimentation settings was carried out based on the description of 41 thin sections and a granulometric analysis of the clastic part of the studied rocks. Results. According to the macroscopic study, the U2 layer is composed of an uneven alternation of silty-argillaceous and silty-sandy rocks with coal interlayers. The rocks are of a polyfacial nature, represented by deposits of continental, transitional, and marine genesis. The thickness of the deposits varies markedly depending on the paleorelief of the area. The optical petrographic study revealed the polymictic composition of the studied rocks, which, according to the classification by V.D. Shutova, correspond to the arkose (graywacke arkose), less often graywacke (feldspar-quartz, quartz-feldspar greywackes) group. Cement most often exhibits a carbonate-clay composition. Rocks of marine genesis are characterized by a decrease in the proportion of rock fragments and an increase in the proportion of mechanically stable accessory minerals (zircon, garnet, tourmaline). The rocks of continental genesis are characterized by the maximum content of micas and plant detritus. An increase in the content of pyrite is noted in the sediments transitional from the continent to the sea. The grain-size analysis data of reservoir rocks of the U2 formation showed that both coastal-marine and channel deposits were formed in environments with active hydrodynamics of the medium, when the dynamic processing of clastic material exceeded the intensity of its supply. Conclusions. The performed lithofacies studies made it possible to reconstruct the sedimentation environment, as well as to reveal specific features in the distribution of the silty-sandy rock components of the U2 formation.
研究课题。北下瓦尔托夫斯克单系内科加里姆地区东部的上巴蒂安沉积层（U2层）。研究目的重建科加里姆地区 U2 地层的沉积环境。材料和方法。根据对岩心样本的宏观描述以及对 35 口井的岩石结构和纹理特征的鉴定，重建了沉积环境。根据对 41 个薄切片的描述和对所研究岩石碎屑部分的粒度分析，对沉积环境进行了澄清。研究结果根据宏观研究，U2 层由淤泥质-砾岩和淤泥质-砂岩不均匀交替组成，并有煤夹层。这些岩石具有多面性，由大陆成因、过渡成因和海洋成因的沉积物组成。根据该地区的古地形，沉积厚度变化明显。根据 V.D. Shutova 的分类，所研究的岩石属于霰岩（灰岩霰岩），较少属于灰岩（长石-石英、石英-长石灰岩）。水泥最常见的成分是碳酸盐-粘土。海洋成因岩石的特征是岩石碎块比例减少，机械稳定的附属矿物（锆石、石榴石、电气石）比例增加。大陆成因岩石的特点是云母和植物碎屑含量最高。在从大陆向海洋过渡的沉积物中，黄铁矿的含量有所增加。U2 构造储层岩石的粒度分析数据表明，沿海-海洋沉积和河道沉积都是在介质水动力活跃的环境中形成的，当时碎屑物质的动态加工超过了其供应强度。结论所进行的岩相研究可以重建沉积环境，并揭示 U2 地层淤泥质砂岩成分分布的具体特征。
{"title":"Relationship of lithological data with the sedimentation environment of the Upper Batian deposits of the Kogalym region","authors":"G. M. Galimova, S. V. Astarkin, E. V. Gibadullina, A. Tatarintseva","doi":"10.24930/1681-9004-2024-24-1-49-62","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-49-62","url":null,"abstract":"Research subject. Upper Batian deposits (formation U2) of the Eastern part of the Kogalym region, within the North Nizhnevartovsk monocline. Aim. Reconstruction of the sedimentation environment of the U2 formation in the Kogalym region. Materials and methods. The reconstruction of sedimentation environments was conducted based on a macroscopic description of core samples with identification of structural and textural features of rocks from 35 wells. The clarification of sedimentation settings was carried out based on the description of 41 thin sections and a granulometric analysis of the clastic part of the studied rocks. Results. According to the macroscopic study, the U2 layer is composed of an uneven alternation of silty-argillaceous and silty-sandy rocks with coal interlayers. The rocks are of a polyfacial nature, represented by deposits of continental, transitional, and marine genesis. The thickness of the deposits varies markedly depending on the paleorelief of the area. The optical petrographic study revealed the polymictic composition of the studied rocks, which, according to the classification by V.D. Shutova, correspond to the arkose (graywacke arkose), less often graywacke (feldspar-quartz, quartz-feldspar greywackes) group. Cement most often exhibits a carbonate-clay composition. Rocks of marine genesis are characterized by a decrease in the proportion of rock fragments and an increase in the proportion of mechanically stable accessory minerals (zircon, garnet, tourmaline). The rocks of continental genesis are characterized by the maximum content of micas and plant detritus. An increase in the content of pyrite is noted in the sediments transitional from the continent to the sea. The grain-size analysis data of reservoir rocks of the U2 formation showed that both coastal-marine and channel deposits were formed in environments with active hydrodynamics of the medium, when the dynamic processing of clastic material exceeded the intensity of its supply. Conclusions. The performed lithofacies studies made it possible to reconstruct the sedimentation environment, as well as to reveal specific features in the distribution of the silty-sandy rock components of the U2 formation.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"28 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140261732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-05DOI: 10.24930/1681-9004-2024-24-1-5-28
V. V. Kholodnov, E. S. Shagalov, G. A. Petrov
Research subject. Hypabyssal intrusive bodies of a gabbro-dolerite-monzonite-granodiorite composition, common among the Devonian island-arc sequences of the East Tagil structural-formational zone in the Northern Urals. These bodies are dated as the Late Devonian-Early Carboniferous and attributed to the post-accretionary continuously differentiated Ivdel complex. Material and methods. The composition of rock-forming and accessory minerals of these intrusive bodies was studied using an SX-100 microanalyzer. This made it possible to obtain new data on the conditions of their formation, features of the fluid regime, and potential ore content. In addition, the geodynamic setting of this period was clarified, along with the composition, possible position of the primary mantle source, and the features of its fluid regime. Results. It was established that the mafic rocks (dolerites) in the Ivdel complex correspond to derivatives of the depleted mantle, with a primary source close to N-MORB basalts. The connection between the source and the separation of the slab and the “mantle window” located under the frontal zone of the former East Tagil island arc was substantiated. Such a position of the melting chamber determines the primary weak water saturation of dolerite magmas and their redox regime. According to mineralogical data, this feature is further manifested in the formation of the entire series of rocks of the Ivdel complex (with an increase in the iron index of clinopyroxenes and amphiboles, an increase in titanium contents in titanomagnetite, and other data). Further evolution of magmas (from dolerites to monzonites, quartz diorites, and granodiorites) occurred as they moved upward to the Earth’s surface and reflected the increasing contamination of differentiated melts by suprasubduction island-arc matter. Another important petrological feature of this complex is its formation with the participation of a chlorine-rich magmatogenic fluid. Depending on the composition of intruding melts, their contents of water, chlorine and oxygen activity, a number of autonomous degassing fluid-magmatic systems are formed. These systems are characterized by noticeable features in the processes of post-magmatic autometasomatosis, with the participation of an iron-chloride fluid. According to the regime of volatiles (halogens, water, and oxygen), the common affiliation of such autonomous fluid-magmatic systems to titanomagnetite ferrofacies (according to G.B. Fershtater), determines both their general metallogenic specialization and potential ore content. The removal of volatiles from such fluid-magmatic systems could be accompanied by extraction and transfer of chlorophyll ore elements from crystallizing melts to exocontacts of intrusive bodies. This, in the presence of migration zones favorable for fluids (faults, crushing zones, etc.) and geochemical barriers (especially in the presence of favorable enclosing sulfide-bearing island-arc strata), could have contri
{"title":"Mineralogy, fluid regime and potential ore content of the post-accretion Ivdel gabbrodolerite-monzonite-granodiorite complex (Northern Urals)","authors":"V. V. Kholodnov, E. S. Shagalov, G. A. Petrov","doi":"10.24930/1681-9004-2024-24-1-5-28","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-5-28","url":null,"abstract":"Research subject. Hypabyssal intrusive bodies of a gabbro-dolerite-monzonite-granodiorite composition, common among the Devonian island-arc sequences of the East Tagil structural-formational zone in the Northern Urals. These bodies are dated as the Late Devonian-Early Carboniferous and attributed to the post-accretionary continuously differentiated Ivdel complex. Material and methods. The composition of rock-forming and accessory minerals of these intrusive bodies was studied using an SX-100 microanalyzer. This made it possible to obtain new data on the conditions of their formation, features of the fluid regime, and potential ore content. In addition, the geodynamic setting of this period was clarified, along with the composition, possible position of the primary mantle source, and the features of its fluid regime. Results. It was established that the mafic rocks (dolerites) in the Ivdel complex correspond to derivatives of the depleted mantle, with a primary source close to N-MORB basalts. The connection between the source and the separation of the slab and the “mantle window” located under the frontal zone of the former East Tagil island arc was substantiated. Such a position of the melting chamber determines the primary weak water saturation of dolerite magmas and their redox regime. According to mineralogical data, this feature is further manifested in the formation of the entire series of rocks of the Ivdel complex (with an increase in the iron index of clinopyroxenes and amphiboles, an increase in titanium contents in titanomagnetite, and other data). Further evolution of magmas (from dolerites to monzonites, quartz diorites, and granodiorites) occurred as they moved upward to the Earth’s surface and reflected the increasing contamination of differentiated melts by suprasubduction island-arc matter. Another important petrological feature of this complex is its formation with the participation of a chlorine-rich magmatogenic fluid. Depending on the composition of intruding melts, their contents of water, chlorine and oxygen activity, a number of autonomous degassing fluid-magmatic systems are formed. These systems are characterized by noticeable features in the processes of post-magmatic autometasomatosis, with the participation of an iron-chloride fluid. According to the regime of volatiles (halogens, water, and oxygen), the common affiliation of such autonomous fluid-magmatic systems to titanomagnetite ferrofacies (according to G.B. Fershtater), determines both their general metallogenic specialization and potential ore content. The removal of volatiles from such fluid-magmatic systems could be accompanied by extraction and transfer of chlorophyll ore elements from crystallizing melts to exocontacts of intrusive bodies. This, in the presence of migration zones favorable for fluids (faults, crushing zones, etc.) and geochemical barriers (especially in the presence of favorable enclosing sulfide-bearing island-arc strata), could have contri","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"19 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140264214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-05DOI: 10.24930/1681-9004-2024-24-1-29-48
A. V. Maslov
Research subject. Clay rocks of the Lower, Middle, and Upper Riphean (respectively, the Burzyan, Yurmatau, and Karatau groups) of the Western slope of the Southern Urals. Changes in their characteristic values of a number of ratios of oxides and some trace elements that are indicators of rock composition in provenances are considered, taking into account the breaks of different duration present in the Riphean stratotype. Methods. Calculation of t he average values of TiO2/Al2O3, Th/Sc, La/Co and (La/Yb)N, typical for shales, fine-grained clay siltstones, and mudstones of the main lithostratigraphic units of the Riphean stratotype (formation and, in some cases, subformation) and analysis of their changes taking into account the hiatuses known in the Riphean stratotype (Pre-Mashak/Pre-Zigalga, Pre- Zilmerdak, Pre-Minyar, Pred-Uk). Results. It was established that throughout the entire Riphean, regardless of breaks in sedimentation, presumably associated with certain transformations in the areas of erosion and sedimentation, a number of lithogeochemical characteristics of fine-grained clastic rocks of the Burzyan, Yurmatau, and Karatau groups (such as TiO2/Al2O3, Th/Sc, La/Co, and, to a significant extent, (La/Yb)N) practically did not experience significant changes. Conclusions. The data obtained give reason to think that there were no fundamental changes in the composition of the sources of fine-grained aluminosiliciclastics for the Riphean sedimentary sequences for more than 1 Ga, and contradict the rather active scenario of tectonic processes at the end of the Early Precambrian and the entire Late Precambrian. Conversely, the data on the values of tNd(DM) and eNd(t) in 37 samples of clay rocks of the Riphean stratotype nevertheless reflect a change in the composition of the rocks of the feeding provinces and, one way or another, fit into the outline of subglobal events established by conventional geological methods in the stratotype area of the Riphean. In accordance with them, in the Ai and Mashak times, an increase in the proportion of juvenile material took place in the areas of erosion. Apparently, the Pre-Zilmerdak hiatus also led to the appearance of a significant proportion of basic igneous rocks among the rocks of the provenances.
{"title":"Some lithogeochemical and isotope-geochemical features of clay rocks and hiatuses in the Riphean stratotype","authors":"A. V. Maslov","doi":"10.24930/1681-9004-2024-24-1-29-48","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-29-48","url":null,"abstract":"Research subject. Clay rocks of the Lower, Middle, and Upper Riphean (respectively, the Burzyan, Yurmatau, and Karatau groups) of the Western slope of the Southern Urals. Changes in their characteristic values of a number of ratios of oxides and some trace elements that are indicators of rock composition in provenances are considered, taking into account the breaks of different duration present in the Riphean stratotype. Methods. Calculation of t he average values of TiO2/Al2O3, Th/Sc, La/Co and (La/Yb)N, typical for shales, fine-grained clay siltstones, and mudstones of the main lithostratigraphic units of the Riphean stratotype (formation and, in some cases, subformation) and analysis of their changes taking into account the hiatuses known in the Riphean stratotype (Pre-Mashak/Pre-Zigalga, Pre- Zilmerdak, Pre-Minyar, Pred-Uk). Results. It was established that throughout the entire Riphean, regardless of breaks in sedimentation, presumably associated with certain transformations in the areas of erosion and sedimentation, a number of lithogeochemical characteristics of fine-grained clastic rocks of the Burzyan, Yurmatau, and Karatau groups (such as TiO2/Al2O3, Th/Sc, La/Co, and, to a significant extent, (La/Yb)N) practically did not experience significant changes. Conclusions. The data obtained give reason to think that there were no fundamental changes in the composition of the sources of fine-grained aluminosiliciclastics for the Riphean sedimentary sequences for more than 1 Ga, and contradict the rather active scenario of tectonic processes at the end of the Early Precambrian and the entire Late Precambrian. Conversely, the data on the values of tNd(DM) and eNd(t) in 37 samples of clay rocks of the Riphean stratotype nevertheless reflect a change in the composition of the rocks of the feeding provinces and, one way or another, fit into the outline of subglobal events established by conventional geological methods in the stratotype area of the Riphean. In accordance with them, in the Ai and Mashak times, an increase in the proportion of juvenile material took place in the areas of erosion. Apparently, the Pre-Zilmerdak hiatus also led to the appearance of a significant proportion of basic igneous rocks among the rocks of the provenances.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"11 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140263546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-09DOI: 10.24930/1681-9004-2023-23-6-1059-1078
S. A. Onishchenko
Research subject. The relationship of sulfide interlayers in silt-pelitic rocks with the cleavage of the axial surface at the Golets Vysochaishii gold-ore black-shale deposit (Bodaibo ore district). Methods. The structure of rocks was studied in out-crops, borehole cores, sanded samples, transparent and polished sections. The chemical composition of minerals was determined. Results. It was established that sulfide and sulfide-containing interlayers undergo deformation and recrystallization together with the host silt-pelitic rocks during plastic dynamometamorphic transformations of rocks. Conclusions. Metamorphic transformations of rocks took place in two stages. During the folding-thrust deformations of the first stage, a cleavage of rocks is formed, which leads to the splintering of sulfide interlayers with the orientation of the lenses along the cleavage. Metamorphic transformations of the second stage are manifested in sulfide and sulfide-containing interlayers in the collective recrystallization of their composing minerals with the replacement of surrounding rocks deformed at the previous stage. The second stage is characterized by changes in the mineral composition of rocks, manifested in the substitution of pyrrhotite with pyrite, increase in the iron content of chlorites and carbonates.
{"title":"Deformation and recrystallization of sulfide interlayers at the Golets Vysochaishii Gold-Ore Black-Shale Deposit","authors":"S. A. Onishchenko","doi":"10.24930/1681-9004-2023-23-6-1059-1078","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-6-1059-1078","url":null,"abstract":"Research subject. The relationship of sulfide interlayers in silt-pelitic rocks with the cleavage of the axial surface at the Golets Vysochaishii gold-ore black-shale deposit (Bodaibo ore district). Methods. The structure of rocks was studied in out-crops, borehole cores, sanded samples, transparent and polished sections. The chemical composition of minerals was determined. Results. It was established that sulfide and sulfide-containing interlayers undergo deformation and recrystallization together with the host silt-pelitic rocks during plastic dynamometamorphic transformations of rocks. Conclusions. Metamorphic transformations of rocks took place in two stages. During the folding-thrust deformations of the first stage, a cleavage of rocks is formed, which leads to the splintering of sulfide interlayers with the orientation of the lenses along the cleavage. Metamorphic transformations of the second stage are manifested in sulfide and sulfide-containing interlayers in the collective recrystallization of their composing minerals with the replacement of surrounding rocks deformed at the previous stage. The second stage is characterized by changes in the mineral composition of rocks, manifested in the substitution of pyrrhotite with pyrite, increase in the iron content of chlorites and carbonates.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":" 32","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139628372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-09DOI: 10.24930/1681-9004-2023-23-6-1079-1094
A. Epimakhov, I. V. Chechushkov, D. V. Kiseleva, M. Ankushev, P. Ankusheva
Research subject. Spatial distribution of bioavailable strontium in the South Trans-Urals. Aim. Development and test of a methodology for obtaining a bioavailable strontium map suitable for studying migrations and mobility in the Bronze Age in the Southern Trans-Urals. Methods. Sampling was conducted in 73 loci located in a uniform network in a 25 ± 5 km grid and in 22 additional loci (transects along the intermediate lines in places of complex geological structure). The determination of strontium content was carried out by the ICP-MS method. The strontium isotope composition was measured using an inductively coupled plasma magneto-sector multi-collector mass spectrometer (MC-ICP-MS). Statistical methods included analysis with stem-and-leaf plots; Student’s t-test; ordinary kriging (the mean is unknown) with linear semivariogram; analysis of correlation according to Pearson’s test. Results. The surveyed area is 36 sq. km2. The sample size is 357. Samples for different types have similar mean and median values; the differences occur in the fourth fractional digit. Criterion 1 (n ≥ 0.001) can be used to determine local variability, and Criterion 2 (0.706 < n < 0.716) can be used to assess the origin of ancient individuals, animals, and archaeological objects. The interpolated maps for each sample type were created. All bioavailable strontium maps show similar spatial patterns. Cross-validation revealed areas of the lowest accuracy. Conclusions. The similarity of the distribution of anomalies on the maps of different types suggests the feasibility of the sampling technique. There is a clear tendency for the zones of elevated 87Sr/86Sr values to be associated with the older lithology (0.7106, mean). The lower values (0.7091 ± 0.002) are associated with the younger lithology. Given the complex geological structure and a wide range of rocks in the study area, a positive result is the low differentiation of the zoning of the identified anomalies, which correspond to large structural-formation zones of the Urals. The presented method demonstrates its suitability for studying sublatitudinal migrations of the ancient population of the Southern Trans-Urals.
{"title":"Mapping of bioavailable 87Sr/86Sr in the Southern Trans-Urals","authors":"A. Epimakhov, I. V. Chechushkov, D. V. Kiseleva, M. Ankushev, P. Ankusheva","doi":"10.24930/1681-9004-2023-23-6-1079-1094","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-6-1079-1094","url":null,"abstract":"Research subject. Spatial distribution of bioavailable strontium in the South Trans-Urals. Aim. Development and test of a methodology for obtaining a bioavailable strontium map suitable for studying migrations and mobility in the Bronze Age in the Southern Trans-Urals. Methods. Sampling was conducted in 73 loci located in a uniform network in a 25 ± 5 km grid and in 22 additional loci (transects along the intermediate lines in places of complex geological structure). The determination of strontium content was carried out by the ICP-MS method. The strontium isotope composition was measured using an inductively coupled plasma magneto-sector multi-collector mass spectrometer (MC-ICP-MS). Statistical methods included analysis with stem-and-leaf plots; Student’s t-test; ordinary kriging (the mean is unknown) with linear semivariogram; analysis of correlation according to Pearson’s test. Results. The surveyed area is 36 sq. km2. The sample size is 357. Samples for different types have similar mean and median values; the differences occur in the fourth fractional digit. Criterion 1 (n ≥ 0.001) can be used to determine local variability, and Criterion 2 (0.706 < n < 0.716) can be used to assess the origin of ancient individuals, animals, and archaeological objects. The interpolated maps for each sample type were created. All bioavailable strontium maps show similar spatial patterns. Cross-validation revealed areas of the lowest accuracy. Conclusions. The similarity of the distribution of anomalies on the maps of different types suggests the feasibility of the sampling technique. There is a clear tendency for the zones of elevated 87Sr/86Sr values to be associated with the older lithology (0.7106, mean). The lower values (0.7091 ± 0.002) are associated with the younger lithology. Given the complex geological structure and a wide range of rocks in the study area, a positive result is the low differentiation of the zoning of the identified anomalies, which correspond to large structural-formation zones of the Urals. The presented method demonstrates its suitability for studying sublatitudinal migrations of the ancient population of the Southern Trans-Urals.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"52 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139535047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-09DOI: 10.24930/1681-9004-2023-23-6-1095-1114
A. I. Malyshev, L. Malysheva
Research subject. Selenium mineralization in altered rocks of the Gaisky deposit. Aim. Determination of formation conditions of native selenium in altered rocks. Results. Selenium mineralization is established in three zones of altered rocks in the sides of the 3rd quarry and is confined to the upper part of the sulfur-quartz rocks. Layers with a high content of native selenium and tiemannite are distinguished by a carbon-black color against the general background of yellow-green sulfur-quartz rocks, forming subvertical trickle textures. The maximum propagation of selenium mineralization was found in the southwestern zone of the quarry. Here, selenium-containing rocks are traced vertically by 6 m, forming a lens with a diameter of up to 70 cm. The accumulation of selenium occurs due to its physical properties. Selenium is similar to sulfur in volatility, although it undergoes more intense condensation under decreased temperatures. The accumulation of selenium condensate is facilitated by a silicic acid gel, which prevents the removal of selenium by a hydrothermal flow. Conclusion. The native selenium of the Gaisky deposit is characterized by a hydrothermal genesis, which, along with the presence of monoclinic native sulfur in the rocks, indicates the hydrothermal formation of the entire complex of altered rocks.
{"title":"Native selenium in the apical rocks of the Gaisky copper-pyrite deposit","authors":"A. I. Malyshev, L. Malysheva","doi":"10.24930/1681-9004-2023-23-6-1095-1114","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-6-1095-1114","url":null,"abstract":"Research subject. Selenium mineralization in altered rocks of the Gaisky deposit. Aim. Determination of formation conditions of native selenium in altered rocks. Results. Selenium mineralization is established in three zones of altered rocks in the sides of the 3rd quarry and is confined to the upper part of the sulfur-quartz rocks. Layers with a high content of native selenium and tiemannite are distinguished by a carbon-black color against the general background of yellow-green sulfur-quartz rocks, forming subvertical trickle textures. The maximum propagation of selenium mineralization was found in the southwestern zone of the quarry. Here, selenium-containing rocks are traced vertically by 6 m, forming a lens with a diameter of up to 70 cm. The accumulation of selenium occurs due to its physical properties. Selenium is similar to sulfur in volatility, although it undergoes more intense condensation under decreased temperatures. The accumulation of selenium condensate is facilitated by a silicic acid gel, which prevents the removal of selenium by a hydrothermal flow. Conclusion. The native selenium of the Gaisky deposit is characterized by a hydrothermal genesis, which, along with the presence of monoclinic native sulfur in the rocks, indicates the hydrothermal formation of the entire complex of altered rocks.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":" 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139628103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.24930/1681-9004-2023-23-4-672-682
S. Vyatkin, G. Kriulina, L. D. Bardukhinov, V. K. Garanin
Research subject. The placer diamond deposit of the Morgogor River, Anabar, Yakutia. The geological history of this deposit has not been reliably established, and the root sources remain unknown. Aim. To describe the mineralogical and spectroscopic characteristics of diamonds from the Morgogor river deposit in comparison with the previously studied diamonds from the Ebelyakh river placer. To divide the studied diamonds into genetic groups, presumably reflecting the primary sources of demolition, according to the distribution of A-centers. To assess the stability of mineralogical and spectroscopic features for the identification of genetic groups. Materials and Methods. Data on 1386 diamond crystals mined from 1978 to 2018 were used. Detailed descriptions were made for 1168 of them; IR spectroscopic studies were carried out for 103 diamonds; informative EPR spectra were obtained for 61 diamonds. Results. Using IR spectroscopy data, the Morgogor diamonds were divided into three groups based on the content of A-centers according to the methodology previously developed for the study of Ebelyakh diamonds. The diamonds of the studied groups differed significantly in terms of the habitus and morphology of crystals, the development of plastic deformation processes, the content of inclusions, the presence and diversity of visual luminescence, as well as associations of paramagnetic centers. The difference between the Morgogor and Ebelakh samples consisted in the ratio of the shares of genetic groups, which can be interpreted as the influence of a geographical factor, i.e., location in relation to the sources and directions of demolition at all stages of placer formation. Conclusions. The diamonds of the Morgogor river have the same three primary sources as the diamonds of the Ebelakh river. Statistical separation of crystals by primary sources - genetic groups - is possible based on the distribution of the content of A-centers. This separation forms groups, whose diamonds differ not only in IR characteristics, but also in the morphological features and the nature of luminescence. The statistically significant samples of diamonds from various Anabar placers differ in the ratio of the shares of genetic groups, which reflects their geographical location, adjusted for the directions of demolition in the processes of formation and redeposition of placers. The data obtained can be used to identify the directions of demolition and, ultimately, to search for its primary sources.
{"title":"Diamonds of the Morgogor placer (Anabar, Yakutia)","authors":"S. Vyatkin, G. Kriulina, L. D. Bardukhinov, V. K. Garanin","doi":"10.24930/1681-9004-2023-23-4-672-682","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-672-682","url":null,"abstract":"Research subject. The placer diamond deposit of the Morgogor River, Anabar, Yakutia. The geological history of this deposit has not been reliably established, and the root sources remain unknown. Aim. To describe the mineralogical and spectroscopic characteristics of diamonds from the Morgogor river deposit in comparison with the previously studied diamonds from the Ebelyakh river placer. To divide the studied diamonds into genetic groups, presumably reflecting the primary sources of demolition, according to the distribution of A-centers. To assess the stability of mineralogical and spectroscopic features for the identification of genetic groups. Materials and Methods. Data on 1386 diamond crystals mined from 1978 to 2018 were used. Detailed descriptions were made for 1168 of them; IR spectroscopic studies were carried out for 103 diamonds; informative EPR spectra were obtained for 61 diamonds. Results. Using IR spectroscopy data, the Morgogor diamonds were divided into three groups based on the content of A-centers according to the methodology previously developed for the study of Ebelyakh diamonds. The diamonds of the studied groups differed significantly in terms of the habitus and morphology of crystals, the development of plastic deformation processes, the content of inclusions, the presence and diversity of visual luminescence, as well as associations of paramagnetic centers. The difference between the Morgogor and Ebelakh samples consisted in the ratio of the shares of genetic groups, which can be interpreted as the influence of a geographical factor, i.e., location in relation to the sources and directions of demolition at all stages of placer formation. Conclusions. The diamonds of the Morgogor river have the same three primary sources as the diamonds of the Ebelakh river. Statistical separation of crystals by primary sources - genetic groups - is possible based on the distribution of the content of A-centers. This separation forms groups, whose diamonds differ not only in IR characteristics, but also in the morphological features and the nature of luminescence. The statistically significant samples of diamonds from various Anabar placers differ in the ratio of the shares of genetic groups, which reflects their geographical location, adjusted for the directions of demolition in the processes of formation and redeposition of placers. The data obtained can be used to identify the directions of demolition and, ultimately, to search for its primary sources.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81479855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.24930/1681-9004-2023-23-4-500-514
A. Korsakov, K. Musiyachenko, D. Mikhailenko, S. P. Demin
Research subject. Mineral inclusions in potassium-bearing tourmaline crystals of the Kumdy-Kol microdiamond deposit. Aim. To reconstruct PT conditions for the origin of potassium-bearing tourmalines. Materials and methods. Mineral analysis and element mapping were performed using an X-ray spectral microanalyzer. Raman spectroscopy was used to detect the C and SiO2 polymorphs. Results. For the first time, diamond inclusions were identified in tourmalines with the potassium content ranging from 1.0 to 1.6 wt %. In addition, diamond-bearing zircon was detected in tourmaline crystals, with the K2O content below the detection limit. Previously, diamond inclusions had been exclusively identified only within the most potassium-rich cores of tourmaline crystals, which were approved as a new end member referred to as maruyamaite. Similar to the previous studies, the Kfs inclusions were recognized in both marumaite crystals and tourmaline crystals, with a variable content of potassium. Conclusions. The obtained findings indicate that high-pressure conditions may not be necessary for the formation of potassium-rich tourmaline. The chemical composition of the fluid is most likely to be the main factor controlling the appearance of tourmalines with an unusual composition.
{"title":"Origin of potassium-bearing tourmalines of the Kumdy-Kolsky deposit (Kokchetav massif, Northern Kazakhstan): Study of Mineral inclusions","authors":"A. Korsakov, K. Musiyachenko, D. Mikhailenko, S. P. Demin","doi":"10.24930/1681-9004-2023-23-4-500-514","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-500-514","url":null,"abstract":"Research subject. Mineral inclusions in potassium-bearing tourmaline crystals of the Kumdy-Kol microdiamond deposit. Aim. To reconstruct PT conditions for the origin of potassium-bearing tourmalines. Materials and methods. Mineral analysis and element mapping were performed using an X-ray spectral microanalyzer. Raman spectroscopy was used to detect the C and SiO2 polymorphs. Results. For the first time, diamond inclusions were identified in tourmalines with the potassium content ranging from 1.0 to 1.6 wt %. In addition, diamond-bearing zircon was detected in tourmaline crystals, with the K2O content below the detection limit. Previously, diamond inclusions had been exclusively identified only within the most potassium-rich cores of tourmaline crystals, which were approved as a new end member referred to as maruyamaite. Similar to the previous studies, the Kfs inclusions were recognized in both marumaite crystals and tourmaline crystals, with a variable content of potassium. Conclusions. The obtained findings indicate that high-pressure conditions may not be necessary for the formation of potassium-rich tourmaline. The chemical composition of the fluid is most likely to be the main factor controlling the appearance of tourmalines with an unusual composition.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"105 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88413952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.24930/1681-9004-2023-23-4-701-713
V. A. Chuiko, V. A. Sinkin, V. A. Naumov, I. A. Plyusnin, K. P. Kalinin
Research subject. Geological features of the structure and composition of the Syuzevskoye diamond placer in the Aleksandrovsky region of the Perm Krai. The placer was found in the border zone of two regional tectonic structures of the Urals: the Western Ural outer folding zone and the Central Ural uplift. This placer was developed within the erosion-karst (?), erosion-structural or tectonically determined Chikman-Nyarskaya depression. Materials and methods. The placer was identified in the period from 2017 to 2022 during a geological study of the subsoil area “Glubokiy” (License PEM 02687 KP LLC “Almining”). Mining and enrichment works were carried out according to the original enrichment scheme using the clamshell sampling method, heavy media and electromagnetic separation. The morphometric characteristics of several hundred diamonds were identified and described; reports were prepared; and reserves were assessed. Results. In the section of the Syuzevskoye placer, two diamond-bearing strata are clearly distinguished, separated by poor- and non-diamond-bearing deposits; anomalously high seam thickness for the Ural placers (up to 14-16 m) was established; high areal productivity of the placer (up to 0.7-1.2 ct/m2) and high diamond content (up to 0.5 ct/m3 per sample and an average of 0.09 ct/m3 for the placer). The placer is attributed to the type of placers of tectonic scarp zones. Reserves of alluvial diamonds weighing 430.5 thousand ct of the Syuzevskoye deposit are estimated at C1 + C2 categories in the area limited by the area between exploration lines 107-116 (size 1000 x 750 m); approved by the Minutes of the GKZ Rosnedra No. 7139 dated November 18, 2022 and will be increased. Certificate No. PEM 23 DRK 10147 confirming the discovery of a mineral deposit, issued by the Federal Agency for Subsoil Use of the Russian Federation to LLC Almining on March 29, 2023. Over 90% of diamonds are of gem quality. The average mass of crystals in the reserve calculation loop is 87 mg, and behind the loops is 29 mg. The leading size classes by mass -8 + 4 and -4 + 2 mm are 93.9% and 72.3% in quantity with an average mass of a diamond crystal of 99.9 mg. The shape is dominated by dodecahedroids (66.9%), less fragments of crystals with an unpreserved shape (14.9%) and fragments of crystals (13.1%); octahedrons (2.4%) and tetrahedroids (2.2%) are rare, rhombic dodecahedroids (0.4%) are rare. The preservation of crystals is good: full crystals make up 63.7%, fragments of crystals - 16.3%, fragments - 12.9%. Most of the crystals do not have wear (42.4%), or have weak wear of the tops and ribs (43.0%), medium and strong wear was noted only in 13.7% of the crystals. The average cost of diamonds is estimated at 361.59 USD per 1 ct. Conclusions. A unique deep-seated diamond deposit has been discovered, which is considered as a new type of deep-seated diamond-bearing placers in tectonic ledge zones. The geological criteria for identifying such diamond deposits in the
{"title":"Syuzevskoye diamond placer: A new stage in studying the diamond potential of Western Urals","authors":"V. A. Chuiko, V. A. Sinkin, V. A. Naumov, I. A. Plyusnin, K. P. Kalinin","doi":"10.24930/1681-9004-2023-23-4-701-713","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-701-713","url":null,"abstract":"Research subject. Geological features of the structure and composition of the Syuzevskoye diamond placer in the Aleksandrovsky region of the Perm Krai. The placer was found in the border zone of two regional tectonic structures of the Urals: the Western Ural outer folding zone and the Central Ural uplift. This placer was developed within the erosion-karst (?), erosion-structural or tectonically determined Chikman-Nyarskaya depression. Materials and methods. The placer was identified in the period from 2017 to 2022 during a geological study of the subsoil area “Glubokiy” (License PEM 02687 KP LLC “Almining”). Mining and enrichment works were carried out according to the original enrichment scheme using the clamshell sampling method, heavy media and electromagnetic separation. The morphometric characteristics of several hundred diamonds were identified and described; reports were prepared; and reserves were assessed. Results. In the section of the Syuzevskoye placer, two diamond-bearing strata are clearly distinguished, separated by poor- and non-diamond-bearing deposits; anomalously high seam thickness for the Ural placers (up to 14-16 m) was established; high areal productivity of the placer (up to 0.7-1.2 ct/m2) and high diamond content (up to 0.5 ct/m3 per sample and an average of 0.09 ct/m3 for the placer). The placer is attributed to the type of placers of tectonic scarp zones. Reserves of alluvial diamonds weighing 430.5 thousand ct of the Syuzevskoye deposit are estimated at C1 + C2 categories in the area limited by the area between exploration lines 107-116 (size 1000 x 750 m); approved by the Minutes of the GKZ Rosnedra No. 7139 dated November 18, 2022 and will be increased. Certificate No. PEM 23 DRK 10147 confirming the discovery of a mineral deposit, issued by the Federal Agency for Subsoil Use of the Russian Federation to LLC Almining on March 29, 2023. Over 90% of diamonds are of gem quality. The average mass of crystals in the reserve calculation loop is 87 mg, and behind the loops is 29 mg. The leading size classes by mass -8 + 4 and -4 + 2 mm are 93.9% and 72.3% in quantity with an average mass of a diamond crystal of 99.9 mg. The shape is dominated by dodecahedroids (66.9%), less fragments of crystals with an unpreserved shape (14.9%) and fragments of crystals (13.1%); octahedrons (2.4%) and tetrahedroids (2.2%) are rare, rhombic dodecahedroids (0.4%) are rare. The preservation of crystals is good: full crystals make up 63.7%, fragments of crystals - 16.3%, fragments - 12.9%. Most of the crystals do not have wear (42.4%), or have weak wear of the tops and ribs (43.0%), medium and strong wear was noted only in 13.7% of the crystals. The average cost of diamonds is estimated at 361.59 USD per 1 ct. Conclusions. A unique deep-seated diamond deposit has been discovered, which is considered as a new type of deep-seated diamond-bearing placers in tectonic ledge zones. The geological criteria for identifying such diamond deposits in the","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73712885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.24930/1681-9004-2023-23-4-515-530
A. Dymshits, E. A. Muraveva, N. S. Tychkov, S. Kostrovitsky, I. Sharygin, A. V. Golovin, O. B. Oleinikov
Research subject. Clinopyroxene xenocrysts from the heavy-mineral concentrates of 14 kimberlite bodies (western part of the field: Obnazhennaya, Rubin, Seraya, Vodorazdelnaya, Vtorogodnitsa, Antoshka; central part of the field: Sliudyanka, Skiff II; western part of the field: Irina, Noyabrskaya, Vechernyaya, Lyusya, Dianga and Zhila 79) of the Kuoika field (Yakutian diamondiferous province, Siberian craton). Aim. To reconstruct the mantle paleogeotherms Under the six kimberlite pipes (Vodorazdelnaya, Obnazhennaya, Vtorogodnitsa, Sliudyanka, Dianga, and Zhila 79) using two independent approaches. Materials and methods. The chemical composition of clinopyroxene xenocrysts was investigated and last equilibrium temperatures and pressures were estimated using single-crystal thermobarometry. The geothermal line fitting to the P-T data set was performed using two methods. The first method is based on the D. Hasterok and D.S. Champan model, and the second - on the D. McKenzie model. Results. The value of lithosphere thickness falls within the margin of error for the two methods, being also comparable with earlier reconstructions for the Vtorogodnitsa, Dyanga, and Obnazhennaya pipes. The obtained results indicate that, during the Mesozoic kimberlitic magmatism, the lithosphere thickness beneath the Kuoika field was about 200 km. Conclusion. The determined peculiarities of the chemical composition of clinopyroxene xenocrysts indicate heterogeneity of the lithospheric mantle composition. Different depths of transported mantle material for kimberlite pipes of the Kuoika field, which are coeval and are located a few km apart, may be related to peculiarities of kimberlite magma ascent to the surface and the presence of intermediate magma chambers. The eastern part of the Kuoika field contains more garnet and garnet-spinel peridotites compared to the central and western parts, which may indirectly indicate a greater diamondiferous potential of the eastern block, where the diamondiferous Dianga pipe is located. The absence of diamonds in other discovered pipes of the Kuoika field may be connected with the metasomatic enrichment of the lithospheric mantle in the area of the “diamond window”, which is confirmed by a large number of high-temperature clinopyroxenes at these depths.
研究课题。14个金金利岩体重矿物精矿的斜辉石异晶(油田西部:Obnazhennaya、Rubin、Seraya、Vodorazdelnaya、Vtorogodnitsa、Antoshka;中部:斯柳京卡，小艇II号;油田西部:Kuoika油田的Irina、Noyabrskaya、Vechernyaya、Lyusya、Dianga和Zhila 79)(雅库特钻石产地，西伯利亚克拉通)。的目标。利用两种独立的方法重建了6个金伯利岩管道(Vodorazdelnaya、Obnazhennaya、Vtorogodnitsa、Sliudyanka、Dianga和Zhila 79)下的地幔古地热。材料和方法。研究了斜辉石异晶的化学成分，并利用单晶测温法测定了最后的平衡温度和平衡压力。采用两种方法对P-T数据集进行地热线拟合。第一种方法是基于D. Hasterok和D. s . Champan模型，第二种方法是基于D. McKenzie模型。结果。岩石圈厚度值在两种方法的误差范围内，也与Vtorogodnitsa、Dyanga和Obnazhennaya管道的早期重建结果相当。结果表明，在中生代金伯利岩浆岩活动时期，Kuoika田底岩石圈厚度约为200 km。结论。斜辉石异晶的化学组成特征表明岩石圈地幔组成的非均质性。Kuoika油田金伯利岩管道的地幔物质输运深度不同，它们是同时期的，相距几公里，这可能与金伯利岩岩浆上升到地表的特殊性和中间岩浆房的存在有关。Kuoika油田东部含石榴石和石榴石尖晶石橄榄岩较多，相对于中部和西部，这可能间接表明东部块体含金刚石潜力较大，含金刚石的Dianga管就位于东部块体中。Kuoika油田其他已发现的管道中没有钻石，可能与“钻石窗口”区域岩石圈地幔的交代富集有关，这些深度的大量高温斜辉石岩证实了这一点。
{"title":"Thermal state of the Siberian craton marginal zone at the time of Mesozoic kimberlitic magmatism within the Kuoika field (Yakutian diamondiferous province)","authors":"A. Dymshits, E. A. Muraveva, N. S. Tychkov, S. Kostrovitsky, I. Sharygin, A. V. Golovin, O. B. Oleinikov","doi":"10.24930/1681-9004-2023-23-4-515-530","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-515-530","url":null,"abstract":"Research subject. Clinopyroxene xenocrysts from the heavy-mineral concentrates of 14 kimberlite bodies (western part of the field: Obnazhennaya, Rubin, Seraya, Vodorazdelnaya, Vtorogodnitsa, Antoshka; central part of the field: Sliudyanka, Skiff II; western part of the field: Irina, Noyabrskaya, Vechernyaya, Lyusya, Dianga and Zhila 79) of the Kuoika field (Yakutian diamondiferous province, Siberian craton). Aim. To reconstruct the mantle paleogeotherms Under the six kimberlite pipes (Vodorazdelnaya, Obnazhennaya, Vtorogodnitsa, Sliudyanka, Dianga, and Zhila 79) using two independent approaches. Materials and methods. The chemical composition of clinopyroxene xenocrysts was investigated and last equilibrium temperatures and pressures were estimated using single-crystal thermobarometry. The geothermal line fitting to the P-T data set was performed using two methods. The first method is based on the D. Hasterok and D.S. Champan model, and the second - on the D. McKenzie model. Results. The value of lithosphere thickness falls within the margin of error for the two methods, being also comparable with earlier reconstructions for the Vtorogodnitsa, Dyanga, and Obnazhennaya pipes. The obtained results indicate that, during the Mesozoic kimberlitic magmatism, the lithosphere thickness beneath the Kuoika field was about 200 km. Conclusion. The determined peculiarities of the chemical composition of clinopyroxene xenocrysts indicate heterogeneity of the lithospheric mantle composition. Different depths of transported mantle material for kimberlite pipes of the Kuoika field, which are coeval and are located a few km apart, may be related to peculiarities of kimberlite magma ascent to the surface and the presence of intermediate magma chambers. The eastern part of the Kuoika field contains more garnet and garnet-spinel peridotites compared to the central and western parts, which may indirectly indicate a greater diamondiferous potential of the eastern block, where the diamondiferous Dianga pipe is located. The absence of diamonds in other discovered pipes of the Kuoika field may be connected with the metasomatic enrichment of the lithospheric mantle in the area of the “diamond window”, which is confirmed by a large number of high-temperature clinopyroxenes at these depths.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"20 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72617406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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