Pub Date : 2023-09-08DOI: 10.24930/1681-9004-2023-23-4-491-499
V. Sonin, E. Zhimulev, A. Chepurov, A. Turkin, A. Chepurov
Research subject. We present the first results on modeling of the interaction of CaCO3 with metallic Fe in the presence of olivine and serpentine at high P-T parameters in comparison with the CaCO3-Fe system. The relevance of the study is related to the need to study decarbonatization reactions during subduction of crustal matter into the Earth's reduced mantle within the context of the global carbon cycle. Methods. The experiment was carried out using a BARS high-pressure apparatus at a pressure of 4.0 GPa and temperatures of 1400-1500°С with a subsequent study of the obtained samples on a scanning electron microscope equipped with a chemical microanalysis system. Results. CaCO3 was found to be unstable under the implemented conditions. The reaction products were iron carbide and Ca-wustite or Ca-magnesiowustite in the presence of silicate phases. Conclusions. The interaction of CaCO3 with metallic Fe at high pressure occurs even if the components are in the solid state. High reaction rates during interaction are provided by the appearance of liquid metal due to the relatively low melting temperature of the eutectic in Fe-C systems. The influence of gravity on the penetration of Fe into the carbonate matrix, which consists in the predominant infiltration of liquid metal between carbonate grains, was established. The presence of H2O significantly reduces the melting point of carbonate, which leads to an increase in the diffusion of components and decarbonization reaction rate, while the effect of gravity also takes place due to the difference in the density of liquid Fe in comparison with other components in a highly fluidized environment.
{"title":"Peculiarities of Fe penetration into the matrix of CaCO3 ± olivine ± serpentine at a pressure of 4 GPa and temperature of 1400-1500°C (experimental data)","authors":"V. Sonin, E. Zhimulev, A. Chepurov, A. Turkin, A. Chepurov","doi":"10.24930/1681-9004-2023-23-4-491-499","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-491-499","url":null,"abstract":"Research subject. We present the first results on modeling of the interaction of CaCO3 with metallic Fe in the presence of olivine and serpentine at high P-T parameters in comparison with the CaCO3-Fe system. The relevance of the study is related to the need to study decarbonatization reactions during subduction of crustal matter into the Earth's reduced mantle within the context of the global carbon cycle. Methods. The experiment was carried out using a BARS high-pressure apparatus at a pressure of 4.0 GPa and temperatures of 1400-1500°С with a subsequent study of the obtained samples on a scanning electron microscope equipped with a chemical microanalysis system. Results. CaCO3 was found to be unstable under the implemented conditions. The reaction products were iron carbide and Ca-wustite or Ca-magnesiowustite in the presence of silicate phases. Conclusions. The interaction of CaCO3 with metallic Fe at high pressure occurs even if the components are in the solid state. High reaction rates during interaction are provided by the appearance of liquid metal due to the relatively low melting temperature of the eutectic in Fe-C systems. The influence of gravity on the penetration of Fe into the carbonate matrix, which consists in the predominant infiltration of liquid metal between carbonate grains, was established. The presence of H2O significantly reduces the melting point of carbonate, which leads to an increase in the diffusion of components and decarbonization reaction rate, while the effect of gravity also takes place due to the difference in the density of liquid Fe in comparison with other components in a highly fluidized environment.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76473698","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: 10.24930/1681-9004-2023-23-4-531-548
A. Kalugina, D. Zedgenizov, A. M. Logvinova
Research subject. Spectroscopic features (Raman spectra) of mineral inclusions of peridotite paragenesis (olivine, orthopyroxene, clinopyroxene, garnet) in natural diamonds of the Yakutian diamondiferous province. Materials and methods. A series of diamonds was studied both with single mineral inclusions and with associations of inclusions of peridotite paragenesis. The chemical composition of mineral inclusions in diamonds was determined using an electron probe micro-analyzer (EPMA). The Raman spectra of inclusions were obtained on a spectrometer equipped with a Nd:YAG laser with a wavelength of 532 nm. Results. The revealed spectroscopic characteristics of mineral inclusions in natural diamonds reflect specific features of their chemical composition. Thus, the shift in the positions of the Raman peaks DB1 and DB2 in the olivine spectra reflects the forsterite - fayalite (Mg-Fe) isomorphism; changes in the positions of valence vibrational modes in the Raman spectra of clinopyroxene Si-Onbr (ν16) and Si-Obr (ν11) and orthopyroxene (ν17) reflect the isomorphism of diopside - jadeite (CaMg-NaAl) and enstatite - ferrosilite (Mg-Fe), position shifts of deformation (ν2) and valence (ν1, ν3) modes of vibrational energies of the Si-O bond in garnets reflect the Al-Cr and Ca-Mg isomorphism, respectively. Conclusions. For the identified correlations, regression lines were calculated, which can be used to determine the quantitative contents of the main chemical components of mineral inclusions (clinopyroxene and garnet) of peridotite paragenesis in situ in diamonds. The developed method for evaluating the chemical composition of garnet and clinopyroxene inclusions can be used to distinguish clinopyroxene and garnet inclusions from different mantle parageneses.
{"title":"Raman Spectroscopy for Characterization of Peridotite Paragenesis Mineral Inclusions in Diamonds","authors":"A. Kalugina, D. Zedgenizov, A. M. Logvinova","doi":"10.24930/1681-9004-2023-23-4-531-548","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-531-548","url":null,"abstract":"Research subject. Spectroscopic features (Raman spectra) of mineral inclusions of peridotite paragenesis (olivine, orthopyroxene, clinopyroxene, garnet) in natural diamonds of the Yakutian diamondiferous province. Materials and methods. A series of diamonds was studied both with single mineral inclusions and with associations of inclusions of peridotite paragenesis. The chemical composition of mineral inclusions in diamonds was determined using an electron probe micro-analyzer (EPMA). The Raman spectra of inclusions were obtained on a spectrometer equipped with a Nd:YAG laser with a wavelength of 532 nm. Results. The revealed spectroscopic characteristics of mineral inclusions in natural diamonds reflect specific features of their chemical composition. Thus, the shift in the positions of the Raman peaks DB1 and DB2 in the olivine spectra reflects the forsterite - fayalite (Mg-Fe) isomorphism; changes in the positions of valence vibrational modes in the Raman spectra of clinopyroxene Si-Onbr (ν16) and Si-Obr (ν11) and orthopyroxene (ν17) reflect the isomorphism of diopside - jadeite (CaMg-NaAl) and enstatite - ferrosilite (Mg-Fe), position shifts of deformation (ν2) and valence (ν1, ν3) modes of vibrational energies of the Si-O bond in garnets reflect the Al-Cr and Ca-Mg isomorphism, respectively. Conclusions. For the identified correlations, regression lines were calculated, which can be used to determine the quantitative contents of the main chemical components of mineral inclusions (clinopyroxene and garnet) of peridotite paragenesis in situ in diamonds. The developed method for evaluating the chemical composition of garnet and clinopyroxene inclusions can be used to distinguish clinopyroxene and garnet inclusions from different mantle parageneses.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"90 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78696007","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: 10.24930/1681-9004-2023-23-4-549-563
E. A. Vasilev, V. N. Ustinov, S. I. Leshukov, R. N. Pendeliak, E. V. Nikolaeva
Research subject. The article presents the results of studying 500 diamond crystals from the core of exploration boreholes of crater and diatreme facies of the upper part of V. Grib kimberlite pipe. Crystals from tuffs and tuffites (crater), tufobreccia, autolith kimberlite breccia and porphyry kimberlite (diatreme) were analyzed separately. aim. To carry out a morphological and spectroscopic study of diamonds from V. Grib pipe. Materials and Methods. An VERTEX-70 spectrometer with a Hyperion 1000 microscope was used to determine the total nitrogen concentration and the share of nitrogen in the form of B defects (NBS), the absorption coefficients of the “platelet” bands B', 3107 cm-1. Images of photoluminescence (PL) were recorded at 360 nm excitation by an ALROSA VIEW PRO device, in order to detect inhomogeneities and color of PL. The PL spectra were recorded by a Horiba FL-3 spectrometer with an excitation of 350 and 450 nm at 300 K and by an InVia Renishaw spectrometer with an excitation of 405, 488 and 787 nm at 77 K. Results. The distribution of diamonds in terms of nitrogen concentration and NBS is specific; about 50% of the crystals are located along one isotherm, the proportion of low-nitrogen crystals is 5%. The PL spectra of 25% of crystals showed the lines of 883/885 nm of an elementary Ni-containing defect. Most crystals with this defect have less than 400 ppm of nitrogen, but they occupy the entire range according to NBS. This system is found in the spectra of 76% of twins and intergrowth; the latter are of 36% of diamonds with the lines 883/885 nm. The studied diamonds differ from those found in M.V. Lomonosov deposit in terms of a much lower content of crystals of cubic habitus (2 and 15%), a lower degree of dissolution (octahedra, respectively, 33 and 15%), a low proportion of colored stones, as well as a wide range of nitrogen concentration and NBS. Conclusion. The revealed features indicate the specific growth conditions of diamonds from V. Grib deposit, which differed from those of diamonds from other kimberlitic bodies of the East European, Siberian platforms and the Urals. The high proportion of low-nitrogen crystals and Ni-containing diamonds is a possible indicator for the presence of large CLIPPIR-type crystals.
{"title":"Diamonds from V. Grib kimberlite pipe: Morphology and spectroscopic features","authors":"E. A. Vasilev, V. N. Ustinov, S. I. Leshukov, R. N. Pendeliak, E. V. Nikolaeva","doi":"10.24930/1681-9004-2023-23-4-549-563","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-549-563","url":null,"abstract":"Research subject. The article presents the results of studying 500 diamond crystals from the core of exploration boreholes of crater and diatreme facies of the upper part of V. Grib kimberlite pipe. Crystals from tuffs and tuffites (crater), tufobreccia, autolith kimberlite breccia and porphyry kimberlite (diatreme) were analyzed separately. aim. To carry out a morphological and spectroscopic study of diamonds from V. Grib pipe. Materials and Methods. An VERTEX-70 spectrometer with a Hyperion 1000 microscope was used to determine the total nitrogen concentration and the share of nitrogen in the form of B defects (NBS), the absorption coefficients of the “platelet” bands B', 3107 cm-1. Images of photoluminescence (PL) were recorded at 360 nm excitation by an ALROSA VIEW PRO device, in order to detect inhomogeneities and color of PL. The PL spectra were recorded by a Horiba FL-3 spectrometer with an excitation of 350 and 450 nm at 300 K and by an InVia Renishaw spectrometer with an excitation of 405, 488 and 787 nm at 77 K. Results. The distribution of diamonds in terms of nitrogen concentration and NBS is specific; about 50% of the crystals are located along one isotherm, the proportion of low-nitrogen crystals is 5%. The PL spectra of 25% of crystals showed the lines of 883/885 nm of an elementary Ni-containing defect. Most crystals with this defect have less than 400 ppm of nitrogen, but they occupy the entire range according to NBS. This system is found in the spectra of 76% of twins and intergrowth; the latter are of 36% of diamonds with the lines 883/885 nm. The studied diamonds differ from those found in M.V. Lomonosov deposit in terms of a much lower content of crystals of cubic habitus (2 and 15%), a lower degree of dissolution (octahedra, respectively, 33 and 15%), a low proportion of colored stones, as well as a wide range of nitrogen concentration and NBS. Conclusion. The revealed features indicate the specific growth conditions of diamonds from V. Grib deposit, which differed from those of diamonds from other kimberlitic bodies of the East European, Siberian platforms and the Urals. The high proportion of low-nitrogen crystals and Ni-containing diamonds is a possible indicator for the presence of large CLIPPIR-type crystals.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78710514","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: 10.24930/1681-9004-2023-23-4-637-653
V. A. Dushin, S. G. Sustavov, D. Prokopchuk, E. N. Volchek
Research subject. To characterize the Sylva fluidogenic-explosive complex, which was established in the junction area of the West Ural thrust megazone (head of the Sylva River) and the eastern wing of the Yuryuzano-Sylva depression of the Pre-Ural trough. Materials and methods. The authors' materials collected during research works at GSA200/2 sheet O-40-XXIX (Shalinskaya Ploshchad), as well as those collected during the work under the Priority 2030 Federal Program, were used. Data on the geology, petrochemistry, petrography, structural and tectonic position of clastogenic rock associations in the area of influence of the Main West Ural thrust were employed. Experimental data were obtained using a TESCAN VEGA LMS electron microscope equipped with an Xplore 30 energy dispersive X-ray spectroscopic prefix, and an URS-55 X-ray unit (Ural State Mining University), as well as CPM-35 and Shimadzu EDX-8000 spectrometers and an XRD-7000 diffractometer (Geoanalitik Centre, Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences). Results. For the first time, the mineralogical-petrographic and chemical compositions of diamond-bearing rocks of the Sylva fluidogenic complex were established. Diamonds and minerals contained in the studied rocks were determined by XRD (sanidine, analcime, etc.). The conducted analysis of the rocks suggests their possible fluid-magmatic genesis, which is indicated by mineralogical features, including accessory minerals-indicators of diamond content, the presence of ellipsoid and teardrop-shaped volcanic glass, finely-dispersed bulk and poorly-rolled unsorted fragments of igneous and sedimentary rocks. Conclusions. The results obtained indicate the possibility of manifestation of Early Mesozoic phreatic volcanism in the studied area, which led to the transfer of the Sylva diamond complex and accessory minerals by fluidolites.
{"title":"Diamond-bearing fluidolites in the junction area of East European Platform and Urals fold region","authors":"V. A. Dushin, S. G. Sustavov, D. Prokopchuk, E. N. Volchek","doi":"10.24930/1681-9004-2023-23-4-637-653","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-637-653","url":null,"abstract":"Research subject. To characterize the Sylva fluidogenic-explosive complex, which was established in the junction area of the West Ural thrust megazone (head of the Sylva River) and the eastern wing of the Yuryuzano-Sylva depression of the Pre-Ural trough. Materials and methods. The authors' materials collected during research works at GSA200/2 sheet O-40-XXIX (Shalinskaya Ploshchad), as well as those collected during the work under the Priority 2030 Federal Program, were used. Data on the geology, petrochemistry, petrography, structural and tectonic position of clastogenic rock associations in the area of influence of the Main West Ural thrust were employed. Experimental data were obtained using a TESCAN VEGA LMS electron microscope equipped with an Xplore 30 energy dispersive X-ray spectroscopic prefix, and an URS-55 X-ray unit (Ural State Mining University), as well as CPM-35 and Shimadzu EDX-8000 spectrometers and an XRD-7000 diffractometer (Geoanalitik Centre, Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences). Results. For the first time, the mineralogical-petrographic and chemical compositions of diamond-bearing rocks of the Sylva fluidogenic complex were established. Diamonds and minerals contained in the studied rocks were determined by XRD (sanidine, analcime, etc.). The conducted analysis of the rocks suggests their possible fluid-magmatic genesis, which is indicated by mineralogical features, including accessory minerals-indicators of diamond content, the presence of ellipsoid and teardrop-shaped volcanic glass, finely-dispersed bulk and poorly-rolled unsorted fragments of igneous and sedimentary rocks. Conclusions. The results obtained indicate the possibility of manifestation of Early Mesozoic phreatic volcanism in the studied area, which led to the transfer of the Sylva diamond complex and accessory minerals by fluidolites.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80215434","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: 10.24930/1681-9004-2023-23-4-564-578
M. I. Rakhmanova, O. Yuryeva, D. A. Zedgenizov, N. V. Gubanov
Research subject. Brown diamond crystals from placers of the western slope of the Middle/Northern Urals. Aim. Study of the defect-impurity composition of a sample of brown diamonds from the placers of the western slope of the Middle/ Northern Urals. Methods. In this work, special attention is paid to the analysis of the characteristic spectroscopic features of defects in diamonds from the placers of the western slope of the Middle/Northern Urals using photoluminescence and IR spectroscopy. Results. The studied diamonds from placers of the Middle/Northern Urals are round isometric crystals of a dodecahedral (tetrahexahedral) habitus. According to the results of luminescence (PL) and infrared spectroscopy, three groups of crystals can be distinguished: (i) medium and high nitrogen crystals with low aggregation and dominant defects H3 and 490.7 nm in the PL spectra; (ii) medium and high nitrogen with high aggregation and the predominance of N3 defects in the PL spectra; (iii) low nitrogen with low aggregation and dominant S1 defects in the PL spectra. The first group is characterized by a green glow (excited 405 nm), the second and third groups are characterized by a blue and yellow glow, respectively. The blue glow of the studied crystals is primarily due to the presence of the N3V center. This defect appears as a result of the aggregation sequence of nitrogen impurities and corresponds to diamonds subjected to the highest temperature annealing (1100-1260°C). Diamonds containing the S1 center are characterized by a low content and aggregation of nitrogen compared to crystals of other groups. Group (i) diamond crystals, whose PL spectra are dominated by the H3 and 490.7 nm systems, have a more intense brown color. Conclusions. The data obtained indicate that annealing at higher temperatures is responsible for the formation of N3V centers in highly aggregated diamonds. The low %B1 aggregation and nitrogen content are associated with the presence of a nitrogen getter (presumably titanium) in the S1 center. An intense brown color appears in the group of diamonds with dominant systems A, H3 and 490.7 nm, which indicates a possible relationship between nitrogen and the corresponding optical absorption.
{"title":"Spectroscopic features of brown diamonds from Ural placers","authors":"M. I. Rakhmanova, O. Yuryeva, D. A. Zedgenizov, N. V. Gubanov","doi":"10.24930/1681-9004-2023-23-4-564-578","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-564-578","url":null,"abstract":"Research subject. Brown diamond crystals from placers of the western slope of the Middle/Northern Urals. Aim. Study of the defect-impurity composition of a sample of brown diamonds from the placers of the western slope of the Middle/ Northern Urals. Methods. In this work, special attention is paid to the analysis of the characteristic spectroscopic features of defects in diamonds from the placers of the western slope of the Middle/Northern Urals using photoluminescence and IR spectroscopy. Results. The studied diamonds from placers of the Middle/Northern Urals are round isometric crystals of a dodecahedral (tetrahexahedral) habitus. According to the results of luminescence (PL) and infrared spectroscopy, three groups of crystals can be distinguished: (i) medium and high nitrogen crystals with low aggregation and dominant defects H3 and 490.7 nm in the PL spectra; (ii) medium and high nitrogen with high aggregation and the predominance of N3 defects in the PL spectra; (iii) low nitrogen with low aggregation and dominant S1 defects in the PL spectra. The first group is characterized by a green glow (excited 405 nm), the second and third groups are characterized by a blue and yellow glow, respectively. The blue glow of the studied crystals is primarily due to the presence of the N3V center. This defect appears as a result of the aggregation sequence of nitrogen impurities and corresponds to diamonds subjected to the highest temperature annealing (1100-1260°C). Diamonds containing the S1 center are characterized by a low content and aggregation of nitrogen compared to crystals of other groups. Group (i) diamond crystals, whose PL spectra are dominated by the H3 and 490.7 nm systems, have a more intense brown color. Conclusions. The data obtained indicate that annealing at higher temperatures is responsible for the formation of N3V centers in highly aggregated diamonds. The low %B1 aggregation and nitrogen content are associated with the presence of a nitrogen getter (presumably titanium) in the S1 center. An intense brown color appears in the group of diamonds with dominant systems A, H3 and 490.7 nm, which indicates a possible relationship between nitrogen and the corresponding optical absorption.","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":"86909042","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: 10.24930/1681-9004-2023-23-4-654-671
M. Goloburdina, S. A. Grakhanov, V. F. Proskurnin
Research subject. Diamondiferous explosive detrital and sedimentary volcanoclastic rocks of the Carnian base of the Upper-Triassic confined to the west flank of the Bulkur Anticline in the north-eastern Siberian Platform. Aim. To identify diamondiferous features of Carnian rocks. Materials and methods. The materials collected by the authors while performing prospecting and evaluation works by the OOO Arctic Mining Company in 2022-2023 were used. The materials were represented by field observation results and mineral-petrographic studies. Rock types were defined by petrographic analysis in thin sections using a Leica DM2700P microscope and known classifications. Diamonds and accessory minerals were distinguished from steam sediment samples and described at the central analytical laboratory of the Vilyuysk Geosurvey Expedition, PJSC Alrosa. The estimation of diamond and pyrope content in core- and bulk samples (CPT) was performed considering their direct correlation. Results. The highest concentrations of diamonds were found to be localized in rocks in the west flank of the Bulkur Anticline. These formations were detected in lapilli tuffs, xenotuff breccia and orthotuffites. Paratuffites and tuff aleuro-sandstones exhibit a lesser diamond potential. Conclusions. The diamond potential of rocks of the Carnian base correlates well with the pyrope content and saturation of volcanoclastic materials. Tuff aleuro-sand-stones of the Bulkur member in the Osipay base and overlying shell deposits are considered potentially diamondiferous. Diamondiferous formations possess considerable thickness and productive efficiency, thus assuming a substantial increase in the diamond prospective potential in the Russian Arctic.
{"title":"Petrographic composition of diamond-bearing Carnian formations of the Bulkur anticline the north-eastern Siberian Platform","authors":"M. Goloburdina, S. A. Grakhanov, V. F. Proskurnin","doi":"10.24930/1681-9004-2023-23-4-654-671","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-654-671","url":null,"abstract":"Research subject. Diamondiferous explosive detrital and sedimentary volcanoclastic rocks of the Carnian base of the Upper-Triassic confined to the west flank of the Bulkur Anticline in the north-eastern Siberian Platform. Aim. To identify diamondiferous features of Carnian rocks. Materials and methods. The materials collected by the authors while performing prospecting and evaluation works by the OOO Arctic Mining Company in 2022-2023 were used. The materials were represented by field observation results and mineral-petrographic studies. Rock types were defined by petrographic analysis in thin sections using a Leica DM2700P microscope and known classifications. Diamonds and accessory minerals were distinguished from steam sediment samples and described at the central analytical laboratory of the Vilyuysk Geosurvey Expedition, PJSC Alrosa. The estimation of diamond and pyrope content in core- and bulk samples (CPT) was performed considering their direct correlation. Results. The highest concentrations of diamonds were found to be localized in rocks in the west flank of the Bulkur Anticline. These formations were detected in lapilli tuffs, xenotuff breccia and orthotuffites. Paratuffites and tuff aleuro-sandstones exhibit a lesser diamond potential. Conclusions. The diamond potential of rocks of the Carnian base correlates well with the pyrope content and saturation of volcanoclastic materials. Tuff aleuro-sand-stones of the Bulkur member in the Osipay base and overlying shell deposits are considered potentially diamondiferous. Diamondiferous formations possess considerable thickness and productive efficiency, thus assuming a substantial increase in the diamond prospective potential in the Russian Arctic.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84129085","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: 10.24930/1681-9004-2023-23-4-589-602
Ya.N. Nugumanova, A. D. Kalugina, A. Starikova, A. Doroshkevich, I. Prokopyev
Research subject. This paper presents the results of a study of minerals of the apatite group from aillikites of the Zima alkaline-ultramafic carbonatite complex. Aim. To determine the composition of apatites to characterize the studied rocks and to elucidate the patterns of element distribution in the magma of aillikites in the late crystallization stages. Materials and Methods. Minerals of the apatite group from 6 samples (4 from dikes of the Bol'shetagninsky massif, 1 from the Bushkanai dike, 1 from the Beloziminskaya pipe) were studied. The samples showed similar textural-structural features, differing in the mineral composition of the groundmass. Results. Minerals of the apatite group are widespread in the groundmass of all the studied rocks. They are characterized by idiomorphic, subidiomorphic crystals of homogeneous composition, 10-100 microns in size. Minerals of the apatite group were identified as fluorapatite and hydroxyapatite characterized by a significant SiO2 content (up to 5 wt %), low SrO content (up to 1.5 wt %) and REE2O3 (up to 2 wt %). The studied apatites also include MgO, FeO, Na2O, SO4, and CO3. Fluorapatites from dyke aillikites are characterized by a higher silicon content as compared to apatites from the Beloziminskiy pipe. Apatites from fresh aillikites of the Bushkanai dyke have a relatively higher content of Sr, REE, and F than minerals from serpentinized samples. Conclusions. The composition of the studied apatites has a lower Sr and Ba content than orangeite and lamproite apatites. In terms of Sr, Si and REE contents, the studied apatites are similar to kimberlite and ailikite apatites. Such a difference allows minerals of the apatite group to be used as an indicator mineral for classification of kimberlites and related rocks, but only in combination with petrography and composition of other minerals of the groundmass.
{"title":"Minerals of the apatite group from ultramafic lamprophyres of the Zima alkaline-ultramafic carbonate complex (Urik-Iya graben, Eastern Sayan region)","authors":"Ya.N. Nugumanova, A. D. Kalugina, A. Starikova, A. Doroshkevich, I. Prokopyev","doi":"10.24930/1681-9004-2023-23-4-589-602","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-589-602","url":null,"abstract":"Research subject. This paper presents the results of a study of minerals of the apatite group from aillikites of the Zima alkaline-ultramafic carbonatite complex. Aim. To determine the composition of apatites to characterize the studied rocks and to elucidate the patterns of element distribution in the magma of aillikites in the late crystallization stages. Materials and Methods. Minerals of the apatite group from 6 samples (4 from dikes of the Bol'shetagninsky massif, 1 from the Bushkanai dike, 1 from the Beloziminskaya pipe) were studied. The samples showed similar textural-structural features, differing in the mineral composition of the groundmass. Results. Minerals of the apatite group are widespread in the groundmass of all the studied rocks. They are characterized by idiomorphic, subidiomorphic crystals of homogeneous composition, 10-100 microns in size. Minerals of the apatite group were identified as fluorapatite and hydroxyapatite characterized by a significant SiO2 content (up to 5 wt %), low SrO content (up to 1.5 wt %) and REE2O3 (up to 2 wt %). The studied apatites also include MgO, FeO, Na2O, SO4, and CO3. Fluorapatites from dyke aillikites are characterized by a higher silicon content as compared to apatites from the Beloziminskiy pipe. Apatites from fresh aillikites of the Bushkanai dyke have a relatively higher content of Sr, REE, and F than minerals from serpentinized samples. Conclusions. The composition of the studied apatites has a lower Sr and Ba content than orangeite and lamproite apatites. In terms of Sr, Si and REE contents, the studied apatites are similar to kimberlite and ailikite apatites. Such a difference allows minerals of the apatite group to be used as an indicator mineral for classification of kimberlites and related rocks, but only in combination with petrography and composition of other minerals of the groundmass.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90163862","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: 10.24930/1681-9004-2023-23-4-579-588
M. D. Tomshin, S. Gogoleva
Research subject. Trap sills of the Daldin-Alakit diamond-bearing region of western Yakutia. Aim. To establish the reason for the influence of sedimentary rocks containing kimberlite diatremes on the introduction of basite magma that forms trap sills and the possibility of using the morphology of sills as a search signs for kimberlites. Materials and methods. Sections of trap sills near kimberlites, their structure, petrographic and petrochemical composition of dolerites performing sills were studied. Results. During the formation of kimberlite diatremes, accompanied by pulsating explosions shifting to the top, a significant compaction of the sedimentary rocks containing kimberlites occurs, associated with thermoelastic stress fields. This process leads to the formation of zones near kimberlites, which are difficult to penetrate for relatively viscous, protocrystalline-enriched basite magmas. When such magmas are introduced, the latter before kimberlites form torus-shaped shafts with a sharply increasing power in intrusions. Sometimes magma, flowing around kimberlites, creates “trappless windows”, occasionally splitting into low-power “tongues”. Quite frequently, before kimberlites, sills crumple, acquiring a wave-like shape. Conclusion. All the listed morphological features of traps arise during the introduction of magma, thus providing an indirect method of searching for kimberlites, particularly during the areal drilling of territories covered by continuous trap fields conducted by ALROSA in Western Yakutia.
{"title":"Morphology of trap sills near kimberlites","authors":"M. D. Tomshin, S. Gogoleva","doi":"10.24930/1681-9004-2023-23-4-579-588","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-579-588","url":null,"abstract":"Research subject. Trap sills of the Daldin-Alakit diamond-bearing region of western Yakutia. Aim. To establish the reason for the influence of sedimentary rocks containing kimberlite diatremes on the introduction of basite magma that forms trap sills and the possibility of using the morphology of sills as a search signs for kimberlites. Materials and methods. Sections of trap sills near kimberlites, their structure, petrographic and petrochemical composition of dolerites performing sills were studied. Results. During the formation of kimberlite diatremes, accompanied by pulsating explosions shifting to the top, a significant compaction of the sedimentary rocks containing kimberlites occurs, associated with thermoelastic stress fields. This process leads to the formation of zones near kimberlites, which are difficult to penetrate for relatively viscous, protocrystalline-enriched basite magmas. When such magmas are introduced, the latter before kimberlites form torus-shaped shafts with a sharply increasing power in intrusions. Sometimes magma, flowing around kimberlites, creates “trappless windows”, occasionally splitting into low-power “tongues”. Quite frequently, before kimberlites, sills crumple, acquiring a wave-like shape. Conclusion. All the listed morphological features of traps arise during the introduction of magma, thus providing an indirect method of searching for kimberlites, particularly during the areal drilling of territories covered by continuous trap fields conducted by ALROSA in Western Yakutia.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79557374","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 : 2023-09-07DOI: 10.24930/1681-9004-2023-23-4-683-700
Yu. G. Paktovskiy, A. G. Popov
Research subject. The Takata formation of the Emsian tier of the Lower Devonian (D1tk) in the Urals is a reservoir of Devonian diamonds. Aim. Confirmation and determination of the diamond-bearing conditions of the reservoir. Materials and Methods. Generalization of primary and interpreted geological information. Lithofacial analysis. Historical and geological reconstruction. Cartographic analysis and geological and cartographic modeling in the ArcMapESRY GIS environment using the ModelBuilder module. Results. The Takata formation is part of the Emsian tier of the Lower Devonian. Tectonically, the Takata formation is located in the West Ural Folded Zone. The diamond content in the Urals is spatially related to the outputs of the Takata formation. The industrial diamond-bearing capacity and the highest density of diamond placers are located in the Vishersky, Chykmansky and Chusovskoy diamond-bearing regions of the Northern and Middle Urals within the Perm Krai. In the early Devonian, the Takata Sea existed in the Vishera diamond-bearing area; a large river with a delta flowed in the direction from northwest to southeast. The sediments of the formation comprise the facies cycle: flood-plain - channel alluvium - delta sediments - underwater-delta - marine sediments. Diamonds are concentrated in the thickness of coarse-grained alluvium, small-pebble basal conglomerates that formed on the land-sea boundary of the paleocontinent of the Russian Plate. Three facies types of the Takata formation section are distinguished: continental, coastal-marine and marine. Its diamond-bearing capacity is associated with the continental and coastal-marine sediments of the formation within the Perm Region. To the north and south of the diamond-bearing areas of the Perm Krai, the Takata formation is represented by marine sediments. According to the geodynamic model based on the geological section of the Northern Urals, the alluvial and coastal-marine Takata diamond placers were formed in the early Devonian as a result of the demolition of material from the Russian Plate. The sources of destruction were rocks of the Precambrian, Ordovician and Silurian. The main spatial-geomorphological criterion for searching for diamond-bearing conglomerates of the Takata formation is the maximum distance of demolition from these conglomerations to placers, equal to 500 m.
{"title":"Devonian diamond reservoir of the Urals","authors":"Yu. G. Paktovskiy, A. G. Popov","doi":"10.24930/1681-9004-2023-23-4-683-700","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-683-700","url":null,"abstract":"Research subject. The Takata formation of the Emsian tier of the Lower Devonian (D1tk) in the Urals is a reservoir of Devonian diamonds. Aim. Confirmation and determination of the diamond-bearing conditions of the reservoir. Materials and Methods. Generalization of primary and interpreted geological information. Lithofacial analysis. Historical and geological reconstruction. Cartographic analysis and geological and cartographic modeling in the ArcMapESRY GIS environment using the ModelBuilder module. Results. The Takata formation is part of the Emsian tier of the Lower Devonian. Tectonically, the Takata formation is located in the West Ural Folded Zone. The diamond content in the Urals is spatially related to the outputs of the Takata formation. The industrial diamond-bearing capacity and the highest density of diamond placers are located in the Vishersky, Chykmansky and Chusovskoy diamond-bearing regions of the Northern and Middle Urals within the Perm Krai. In the early Devonian, the Takata Sea existed in the Vishera diamond-bearing area; a large river with a delta flowed in the direction from northwest to southeast. The sediments of the formation comprise the facies cycle: flood-plain - channel alluvium - delta sediments - underwater-delta - marine sediments. Diamonds are concentrated in the thickness of coarse-grained alluvium, small-pebble basal conglomerates that formed on the land-sea boundary of the paleocontinent of the Russian Plate. Three facies types of the Takata formation section are distinguished: continental, coastal-marine and marine. Its diamond-bearing capacity is associated with the continental and coastal-marine sediments of the formation within the Perm Region. To the north and south of the diamond-bearing areas of the Perm Krai, the Takata formation is represented by marine sediments. According to the geodynamic model based on the geological section of the Northern Urals, the alluvial and coastal-marine Takata diamond placers were formed in the early Devonian as a result of the demolition of material from the Russian Plate. The sources of destruction were rocks of the Precambrian, Ordovician and Silurian. The main spatial-geomorphological criterion for searching for diamond-bearing conglomerates of the Takata formation is the maximum distance of demolition from these conglomerations to placers, equal to 500 m.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84773055","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 : 2023-09-07DOI: 10.24930/1681-9004-2023-23-4-476-490
V. Puchkov, D. A. Zedgenizov
Research subject. The present evolutionary stage of geodynamic theory is associated with the idea of thermochemical convection of various levels in the Earth's mantle, where the centrifugal branches are represented by plumes, and the centripetal - by subduction zones. Aim. The study of diamonds contributes to an understanding of when, at what level in mantle, under what P-T conditions and geochemical environment particular diamonds originated, which were then transported by centrifugal convection flows to the Earth's surface, thereby permitting characterization of this flow. Materials and methods. Generalization of published materials and characterization of mineral inclusions in diamonds allow the general structure of mantle convection to be clarified in different epochs and different regions. Results. The data obtained on mineral inclusions in diamonds, along with the experimental data on the P-T conditions of their mineral parageneses and geophysical data on mantle properties, indicate that the depth of diamond formation varies from the lower lithosphere in the upper part of the upper mantle (≈150-250 km) to the bottom of the lower mantle. At the same time, the diamonds containing mineral inclusions, characteristic of the lower mantle, account for only the first percents of the general number of diamonds. Conclusions. The transport of diamonds from different depths of their origin is a reliable indication of convection processes (as a plume activity) in the mantle. This information provides evidence to the real existence of plumes, which is important in the context of ongoing discussions on the depth of their origin. However, the study of mineral inclusions in diamonds, particularly in superdeep diamonds, is a challenging task due to the retrograde changes, resorption and sometimes complete dissolution on their way to the surface. These circumstances minimize the probability of occurrence of superdeep diamonds and require consideration when making judgements about the reality of existence of superdeep diamonds.
{"title":"Mantle convection and diamonds","authors":"V. Puchkov, D. A. Zedgenizov","doi":"10.24930/1681-9004-2023-23-4-476-490","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-4-476-490","url":null,"abstract":"Research subject. The present evolutionary stage of geodynamic theory is associated with the idea of thermochemical convection of various levels in the Earth's mantle, where the centrifugal branches are represented by plumes, and the centripetal - by subduction zones. Aim. The study of diamonds contributes to an understanding of when, at what level in mantle, under what P-T conditions and geochemical environment particular diamonds originated, which were then transported by centrifugal convection flows to the Earth's surface, thereby permitting characterization of this flow. Materials and methods. Generalization of published materials and characterization of mineral inclusions in diamonds allow the general structure of mantle convection to be clarified in different epochs and different regions. Results. The data obtained on mineral inclusions in diamonds, along with the experimental data on the P-T conditions of their mineral parageneses and geophysical data on mantle properties, indicate that the depth of diamond formation varies from the lower lithosphere in the upper part of the upper mantle (≈150-250 km) to the bottom of the lower mantle. At the same time, the diamonds containing mineral inclusions, characteristic of the lower mantle, account for only the first percents of the general number of diamonds. Conclusions. The transport of diamonds from different depths of their origin is a reliable indication of convection processes (as a plume activity) in the mantle. This information provides evidence to the real existence of plumes, which is important in the context of ongoing discussions on the depth of their origin. However, the study of mineral inclusions in diamonds, particularly in superdeep diamonds, is a challenging task due to the retrograde changes, resorption and sometimes complete dissolution on their way to the surface. These circumstances minimize the probability of occurrence of superdeep diamonds and require consideration when making judgements about the reality of existence of superdeep diamonds.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75039978","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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