Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601469
A. V. Grigorieva, A.V. Volkov, N. V. Sidorova
Abstract
For the first time by the method of scanning electron microscopy, REE mineralization studies are conducted in alkaline rhyolites of the Pechalninskii ore field (Northeast Russia), a potentially large-volume source of HREEs. It is shown using the methods of electron microprobe analysis and cathodoluminescence that microcrystalline aggregates of pyroxenes and/or amphiboles in alkaline rhyolites contain the finest inclusions of REE segregations (5–7 µm). Using SEM, it is determined that the largest segregation is cerium phosphate. Concentrically zonal and radial-fibrous REE segregations are revealed in the relics of titanomagnetite crystals by EDS. The first ones are represented by silicates enriched with Y and REEs and the content of each REE varies regularly from the center to the edge. The radial-fibrous aggregates are represented by oxides and/or carbonates containing REEs (La, Ce, and Nd predominate). The results obtained can be used in the development of enrichment technology.
{"title":"REE Mineralization in Alkaline Rhyolites of the Pechalninskii Ore Field (Northeast Russia)","authors":"A. V. Grigorieva, A.V. Volkov, N. V. Sidorova","doi":"10.1134/s1028334x24601469","DOIUrl":"https://doi.org/10.1134/s1028334x24601469","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>For the first time by the method of scanning electron microscopy, REE mineralization studies are conducted in alkaline rhyolites of the Pechalninskii ore field (Northeast Russia), a potentially large-volume source of HREEs. It is shown using the methods of electron microprobe analysis and cathodoluminescence that microcrystalline aggregates of pyroxenes and/or amphiboles in alkaline rhyolites contain the finest inclusions of REE segregations (5–7 µm). Using SEM, it is determined that the largest segregation is cerium phosphate. Concentrically zonal and radial-fibrous REE segregations are revealed in the relics of titanomagnetite crystals by EDS. The first ones are represented by silicates enriched with Y and REEs and the content of each REE varies regularly from the center to the edge. The radial-fibrous aggregates are represented by oxides and/or carbonates containing REEs (La, Ce, and Nd predominate). The results obtained can be used in the development of enrichment technology.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601342
D. A. Lykhin, V. V. Yarmolyuk, A. A. Vorontsov, L. O. Magazina
Abstract
The question of what factors contributed to the formation of rare metal mineralization in alkaline granites of Western Transbaikalia is considered. This work is based on the results of comparison of petro-geochemical characteristics of alkaline granitoids from the nearby ore-bearing Ingur and ore-free Sherbakhtinskii massifs. The rocks of these massifs form a common series of compositions with variations from syenites to alkaline granites (in the Sherbakhtinskii massif) and from alkaline granites to pegmatites (in the Ingur massif). The formation of this series of rocks is associated with a deep differentiation of the original magma common to both massifs, accompanied by a sequential decrease in the magnesium content and the accumulation of rare elements (Be, Ta, Nb, Th, U, HREEs) in residual melts. They reach the highest values in the pegmatites of the Ingur massif, in which rare metal mineralization appears. Its formation is associated with the fact that, according to the thermochronological studies, the Ingur massif was located in the temperature range from 900 to 500°C for 6 Ma. Such a long stay in the region of high temperatures was accompanied not only by deep differentiation of residual melts, but also stimulated fluid activity, which contributed to the redistribution and accumulation of ore elements in pegmatites.
{"title":"Composition and Thermochronology of Alkaline Granites of the Ingur Massif: The Problem of Detection of Factors Contributing to Formation of Rare-Metal Mineralization in Alkaline Granites of Western Transbaikalia","authors":"D. A. Lykhin, V. V. Yarmolyuk, A. A. Vorontsov, L. O. Magazina","doi":"10.1134/s1028334x24601342","DOIUrl":"https://doi.org/10.1134/s1028334x24601342","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The question of what factors contributed to the formation of rare metal mineralization in alkaline granites of Western Transbaikalia is considered. This work is based on the results of comparison of petro-geochemical characteristics of alkaline granitoids from the nearby ore-bearing Ingur and ore-free Sherbakhtinskii massifs. The rocks of these massifs form a common series of compositions with variations from syenites to alkaline granites (in the Sherbakhtinskii massif) and from alkaline granites to pegmatites (in the Ingur massif). The formation of this series of rocks is associated with a deep differentiation of the original magma common to both massifs, accompanied by a sequential decrease in the magnesium content and the accumulation of rare elements (Be, Ta, Nb, Th, U, HREEs) in residual melts. They reach the highest values in the pegmatites of the Ingur massif, in which rare metal mineralization appears. Its formation is associated with the fact that, according to the thermochronological studies, the Ingur massif was located in the temperature range from 900 to 500°C for 6 Ma. Such a long stay in the region of high temperatures was accompanied not only by deep differentiation of residual melts, but also stimulated fluid activity, which contributed to the redistribution and accumulation of ore elements in pegmatites.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x2360367x
Xiaolin Yang, Jinling Yang
Abstract
Deciphering the physical origin of transient crustal deformation is a difficult challenge in the field of continuous borehole observations of crustal movement because the relevant influencing factors of the phenomenon are extremely multifarious. In the Shanxi Rift, squall lines are a frequently occurring mesoscale convective system. Consequently, strain transients are always observed by the borehole dilatometer network within the Shanxi Rift; however, a fundamental understanding of the transient phenomena induced by squall lines remains elusive. To address this challenge, we adopted a second-order Butterworth band-pass filters (0.5–2 h) to retrieve the borehole volumetric deformations excited by a “dry” squall line from September 21, 2017, that occurred in the Shanxi Rift. The elastic loading of Ricker-wavelet-shaped atmospheric waves induced by squall line, which can cause the main signature of transient deformation to adopt a highly similar shape; this pressure-induced deformation process can last approximately 148–164 min and has a maximum magnitude of approximately 19 nstrain. This work of signal processing clearly identifies the crustal transient induced by a squall line and provides new insights into the origin of some short-lasting crustal deformations in the Shanxi Rift and elsewhere.
{"title":"Ricker-wavelet-like Strain Waves in Shanxi Rift, North China: Atmospheric Loading Effect of the Squall Line","authors":"Xiaolin Yang, Jinling Yang","doi":"10.1134/s1028334x2360367x","DOIUrl":"https://doi.org/10.1134/s1028334x2360367x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Deciphering the physical origin of transient crustal deformation is a difficult challenge in the field of continuous borehole observations of crustal movement because the relevant influencing factors of the phenomenon are extremely multifarious. In the Shanxi Rift, squall lines are a frequently occurring mesoscale convective system. Consequently, strain transients are always observed by the borehole dilatometer network within the Shanxi Rift; however, a fundamental understanding of the transient phenomena induced by squall lines remains elusive. To address this challenge, we adopted a second-order Butterworth band-pass filters (0.5–2 h) to retrieve the borehole volumetric deformations excited by a “dry” squall line from September 21, 2017, that occurred in the Shanxi Rift. The elastic loading of Ricker-wavelet-shaped atmospheric waves induced by squall line, which can cause the main signature of transient deformation to adopt a highly similar shape; this pressure-induced deformation process can last approximately 148–164 min and has a maximum magnitude of approximately 19 nstrain. This work of signal processing clearly identifies the crustal transient induced by a squall line and provides new insights into the origin of some short-lasting crustal deformations in the Shanxi Rift and elsewhere.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140602488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601275
S. G. Skolotnev, A. A. Peyve, K. O. Dobrolyubova, A. N. Ivanenko, I. S. Patina, V. A. Bogolyubskiy, V. N. Dobrolyubov, I. A. Veklich, S. A. Dokashenko, V. L. Lyubinetskiy, I. A. Ilyin
Abstract
The structure of King’s Trough and its surroundings (King’s mesostructural cluster), located on the eastern flank of the Mid-Atlantic Ridge in the North Atlantic, is described in this paper. This work is based on geological and geophysical data obtained during the 55th expedition of the R/V Akademik Nikolaj Strakhov. Six provinces were identified within the southeastern part of King’s Trough, based on the results of bathymetric survey. Each province has its own morphostructural feature resulting from multistage tectonic and volcanic processes, which alternate and conjugate with each other in time. According to seismoacoustic profiling data, three main types of seismic facies have been identified: (a) pelagic complexes; (b) deposits of turbidite flows; and (c) chaotic facies of gravity origin. It is shown that the anomalous magnetic field of the study area is the superposition of linear and isometric anomalies. The first were formed during the formation of the oceanic crust in the axial zone of spreading. The second are associated with volcanic massifs formed under intraplate conditions. The obtained data confirm the assumption that the formation of King’s Trough was preceded by the formation of an elongated arched rise, which became a scene of intense intraplate volcanism that increased from southeast to northwest. This stage was followed by subsidence of the axial part of the rise with the formation of King’s Trough and the Peake and Freen Troughs.
{"title":"Structure of the Ocean Floor in the Junction Area of King’s Trough and the Azores–Biscay Rise (North Atlantic)","authors":"S. G. Skolotnev, A. A. Peyve, K. O. Dobrolyubova, A. N. Ivanenko, I. S. Patina, V. A. Bogolyubskiy, V. N. Dobrolyubov, I. A. Veklich, S. A. Dokashenko, V. L. Lyubinetskiy, I. A. Ilyin","doi":"10.1134/s1028334x24601275","DOIUrl":"https://doi.org/10.1134/s1028334x24601275","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The structure of King’s Trough and its surroundings (King’s mesostructural cluster), located on the eastern flank of the Mid-Atlantic Ridge in the North Atlantic, is described in this paper. This work is based on geological and geophysical data obtained during the 55th expedition of the R/V <i>Akademik Nikolaj Strakhov</i>. Six provinces were identified within the southeastern part of King’s Trough, based on the results of bathymetric survey. Each province has its own morphostructural feature resulting from multistage tectonic and volcanic processes, which alternate and conjugate with each other in time. According to seismoacoustic profiling data, three main types of seismic facies have been identified: (a) pelagic complexes; (b) deposits of turbidite flows; and (c) chaotic facies of gravity origin. It is shown that the anomalous magnetic field of the study area is the superposition of linear and isometric anomalies. The first were formed during the formation of the oceanic crust in the axial zone of spreading. The second are associated with volcanic massifs formed under intraplate conditions. The obtained data confirm the assumption that the formation of King’s Trough was preceded by the formation of an elongated arched rise, which became a scene of intense intraplate volcanism that increased from southeast to northwest. This stage was followed by subsidence of the axial part of the rise with the formation of King’s Trough and the Peake and Freen Troughs.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601299
K. A. Savko, A. V. Samsonov, S. V. Tsybulyaev, N. S. Bazikov, E. Kh. Korish, R. A. Terentiev
Abstract
Aillikite dikes of carbonate–biotite composition, intersecting Paleoproterozoic banded iron formations, were discovered in the Kursk block of Sarmatia for the first time. Their age is 2.10–2.07 Ga. The aillikite dikes underwent epidote–amphibolite facies metamorphism (550°С, 2–3 kbar), and they are deformed and foliated. Primary magmatic olivine and pyroxene were not preserved. In terms of geochemistry, ultramafic lamprophyres of the Kursk block are similar to petrotypical aillikites. They are depleted in SiO2 and Al2O3 and enriched in MgO, TiO2, K2O, Cr, Ni, and Nb with highly fractionated LREE and HREE. The highly radiogenic neodymium isotopic composition is indicative of a juvenile enriched (metasomatized) mantle source of aillikites. Positive Nb and Ti anomalies suggest metasomatic alterations of the depleted lithosphere mantle by OIB melts under opening of the Tim back-arc basin. The aillikite dikes and carbonatites of the Dubravinsky complex could have been formed at different melting degrees of a single deep, lithospheric source, enriched in lithophile elements shortly before the melting episode, possibly in a suprasubduction setting about 2.1 Ga.
摘要 在萨尔马特的库尔斯克地块首次发现了碳酸盐-生物岩成分的沸石尖晶石，它们与古近纪带铁地层相交。它们的年龄为 2.10-2.07 Ga。闪长岩尖晶石经历了闪长岩-闪长岩面变质作用（550°С，2-3千巴），并发生了变形和褶皱。原生岩浆橄榄石和辉石没有保存下来。从地球化学角度来看，库尔斯克区块的超基性岩化石类似于典型的岩浆岩。它们的 SiO2 和 Al2O3 含量低，而 MgO、TiO2、K2O、Cr、Ni 和 Nb 含量高，LREE 和 HREE 分馏度高。高放射性钕同位素组成表明榴辉岩来源于幼年富集（变质）地幔。正的 Nb 和 Ti 异常表明，在 Tim 后弧盆地打开的情况下，OIB 熔体对贫化的岩石圈地幔进行了变质改造。Dubravinsky复合体的箭云母尖晶石和碳酸盐岩可能是在一个单一的深岩石圈源的不同熔融程度下形成的，在熔融前不久富含亲岩元素，可能是在大约2.1 Ga的超俯冲环境中形成的。
{"title":"First Discovery of Paleoproterozoic Aillikite Dikes in Sarmatia: Geochemistry and Petrogenesis","authors":"K. A. Savko, A. V. Samsonov, S. V. Tsybulyaev, N. S. Bazikov, E. Kh. Korish, R. A. Terentiev","doi":"10.1134/s1028334x24601299","DOIUrl":"https://doi.org/10.1134/s1028334x24601299","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Aillikite dikes of carbonate–biotite composition, intersecting Paleoproterozoic banded iron formations, were discovered in the Kursk block of Sarmatia for the first time. Their age is 2.10–2.07 Ga. The aillikite dikes underwent epidote–amphibolite facies metamorphism (550°С, 2–3 kbar), and they are deformed and foliated. Primary magmatic olivine and pyroxene were not preserved. In terms of geochemistry, ultramafic lamprophyres of the Kursk block are similar to petrotypical aillikites. They are depleted in SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> and enriched in MgO, TiO<sub>2</sub>, K<sub>2</sub>O, Cr, Ni, and Nb with highly fractionated LREE and HREE. The highly radiogenic neodymium isotopic composition is indicative of a juvenile enriched (metasomatized) mantle source of aillikites. Positive Nb and Ti anomalies suggest metasomatic alterations of the depleted lithosphere mantle by OIB melts under opening of the Tim back-arc basin. The aillikite dikes and carbonatites of the Dubravinsky complex could have been formed at different melting degrees of a single deep, lithospheric source, enriched in lithophile elements shortly before the melting episode, possibly in a suprasubduction setting about 2.1 Ga.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601287
V. V. Yarmolyuk, A. M. Kozlovsky, U. A. Moroz, A. V. Nikiforov
Abstract
New evidence of the Early Silurian sublithospheric magmatic activity in the eastern part of the Altai–Sayan orogen has been obtained. This activity occurred between large-scale mantle-derived magmatic episodes of the Middle–Late Ordovician and Devonian. It involved high-Mg (15–22 wt % MgO) picritic dolerite dikes of the Naryn complex in the western part of the Tuva–Mongolian Superterrane. The dike complex consists of simple picrodolerite dikes and those combined with a central picrodolerite zone and granitoids at contacts with mingling relationships between contrasting rocks. The picrodolerite geochemical signature is similar to enriched basalts of the mid-ocean ridges or intraplate regions and is indicative of a sublithospheric mantle source. Initial picrodolerite melts were formed at a depth of about 120–140 km, a temperature of 1600–1640°C, and a melting degree of up to 20% at a dry peridotite source. These values are consistent with the conditions of the hot spot magmas origin. Granitoids from the combined dikes had a crustal geochemical signature and were formed due to the anatexis of the Tuva–Mongolian Superterrane host rocks initiated by the picrodolerite intrusion. The U–Pb zircon age (SHRIMP-II) of leucogranite from the combined dike is 439 ± 3 Ma interpreted as the age of the Naryn dike complex. The Early Silurian mantle-derived magmatic activity of the Southeastern Tuva most likely caused the migration of the Siberian paleocontinent over the African mantle hot field.
{"title":"Picrodolerite Dikes of the Naryn River: Age, Composition, and Position in the Geological History of Southern Tuva (Central Asian Orogenic Belt)","authors":"V. V. Yarmolyuk, A. M. Kozlovsky, U. A. Moroz, A. V. Nikiforov","doi":"10.1134/s1028334x24601287","DOIUrl":"https://doi.org/10.1134/s1028334x24601287","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>New evidence of the Early Silurian sublithospheric magmatic activity in the eastern part of the Altai–Sayan orogen has been obtained. This activity occurred between large-scale mantle-derived magmatic episodes of the Middle–Late Ordovician and Devonian. It involved high-Mg (15–22 wt % MgO) picritic dolerite dikes of the Naryn complex in the western part of the Tuva–Mongolian Superterrane. The dike complex consists of simple picrodolerite dikes and those combined with a central picrodolerite zone and granitoids at contacts with mingling relationships between contrasting rocks. The picrodolerite geochemical signature is similar to enriched basalts of the mid-ocean ridges or intraplate regions and is indicative of a sublithospheric mantle source. Initial picrodolerite melts were formed at a depth of about 120–140 km, a temperature of 1600–1640°C, and a melting degree of up to 20% at a dry peridotite source. These values are consistent with the conditions of the hot spot magmas origin. Granitoids from the combined dikes had a crustal geochemical signature and were formed due to the anatexis of the Tuva–Mongolian Superterrane host rocks initiated by the picrodolerite intrusion. The U–Pb zircon age (SHRIMP-II) of leucogranite from the combined dike is 439 ± 3 Ma interpreted as the age of the Naryn dike complex. The Early Silurian mantle-derived magmatic activity of the Southeastern Tuva most likely caused the migration of the Siberian paleocontinent over the African mantle hot field.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601184
V. V. Adushkin, A. G. Goev, Yu. A. Vinogradov, A. V. Shapovalov
Abstract
Deep velocity models of the lithosphere of the Khoper Block and Losevskaya Suture Zone of the Voronezh crystalline massif of the Sarmatia Protocraton are obtained for the first time by the receiver function technique. The crust is determined by a four-layered structure with a waveguide in the lower part of the section. The presence of a zone of lower velocities in the upper mantle at depths of 110–150 km, which mark the mid-lithospheric discontinuity (MLD), as well as their characteristics, is identified for the first time for the Khoper Block. A complex, probably, gradient structure of the crustal–mantle transition is determined.
{"title":"Lithosphere of the Northeastern Part of the Sarmatia Protocraton According to New Seismic Data","authors":"V. V. Adushkin, A. G. Goev, Yu. A. Vinogradov, A. V. Shapovalov","doi":"10.1134/s1028334x24601184","DOIUrl":"https://doi.org/10.1134/s1028334x24601184","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Deep velocity models of the lithosphere of the Khoper Block and Losevskaya Suture Zone of the Voronezh crystalline massif of the Sarmatia Protocraton are obtained for the first time by the receiver function technique. The crust is determined by a four-layered structure with a waveguide in the lower part of the section. The presence of a zone of lower velocities in the upper mantle at depths of 110–150 km, which mark the mid-lithospheric discontinuity (MLD), as well as their characteristics, is identified for the first time for the Khoper Block. A complex, probably, gradient structure of the crustal–mantle transition is determined.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Erlian Basin is a Mesozoic–Cenozoic rift basin with a large thick Pliocene sandstones deposit, which has important oil, gas, and uranium resources exploration potential. The paleo-sedimentary environment plays an important role in controlling the development of mineral resource. However, provenance and depositional environment of the Pliocene sandstones remain enigmatic. To address it, this study reports the whole rock geochemical compositions of sandstones from the Youqi and Siziwangqi regions to reflect the paleo-sedimentary environment. The Youqi sandstones are classified as litharenite-arkose, whereas the Siziwangqi sandstones exhibit a graywacke affinity. Furthermore, both the Youqi and Siziwangqi sandstones exhibit low CIA, PIA, ICV, and Th/U values, suggesting that their source rocks were of great maturation and experienced low to moderate chemical weathering processes. The Ni/Co, U/Th, and Ce/Ce* values in these sandstones range from 0.4 to 5.9, 0.20 to 0.37, and 0.80 to 1.09, respectively, indicating that these sandstones were formed in an oxygen-rich depositional environment. Additionally, interelement ratios such as Sr/Cu, SiO2/Al2O3, and Rb/Sr suggest a hot and arid paleoclimate during the deposition of these sandstones. Tectonic discrimination diagrams reveal a continental arc environment for the studied sandstones, Combining regional structural background, implying that the Erlian Basin was influenced by both Himalayan and the Pacific-Ocean-surrounding tectonism during the Pliocene period.
{"title":"Provenance and Depositional Environment of the Pliocene Sandstones from the Erlian Basin, North China","authors":"Fenquan Xie, Bing Hu, Ning Li, Haojie Xu, Hongda Luo, Xiongfei Wang, Chen Zhang","doi":"10.1134/s1028334x24600026","DOIUrl":"https://doi.org/10.1134/s1028334x24600026","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Erlian Basin is a Mesozoic–Cenozoic rift basin with a large thick Pliocene sandstones deposit, which has important oil, gas, and uranium resources exploration potential. The paleo-sedimentary environment plays an important role in controlling the development of mineral resource. However, provenance and depositional environment of the Pliocene sandstones remain enigmatic. To address it, this study reports the whole rock geochemical compositions of sandstones from the Youqi and Siziwangqi regions to reflect the paleo-sedimentary environment. The Youqi sandstones are classified as litharenite-arkose, whereas the Siziwangqi sandstones exhibit a graywacke affinity. Furthermore, both the Youqi and Siziwangqi sandstones exhibit low CIA, PIA, ICV, and Th/U values, suggesting that their source rocks were of great maturation and experienced low to moderate chemical weathering processes. The Ni/Co, U/Th, and Ce/Ce* values in these sandstones range from 0.4 to 5.9, 0.20 to 0.37, and 0.80 to 1.09, respectively, indicating that these sandstones were formed in an oxygen-rich depositional environment. Additionally, interelement ratios such as Sr/Cu, SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub>, and Rb/Sr suggest a hot and arid paleoclimate during the deposition of these sandstones. Tectonic discrimination diagrams reveal a continental arc environment for the studied sandstones, Combining regional structural background, implying that the Erlian Basin was influenced by both Himalayan and the Pacific-Ocean-surrounding tectonism during the Pliocene period.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1134/s1028334x24601305
E. V. Asafov, A. N. Koshlyakova, A. V. Sobolev, D. P. Tobelko, N. N. Koshlyakova, S. V. Mezhelovskaya
Abstract
The Archean–Proterozoic transition in the Earth’s history is marked by significant changes in the mantle dynamics and temperature regimes. A notable consequence is the disappearance of Al-depleted komatiites in the Late Archean and an almost complete absence of Archean-typical peridotitic komatiites since the Proterozoic. This work presents a study of the 2.41 Ga komatiitic basalts from the Vetrenyi Belt, dating back to the early Proterozoic. Unique data on the compositions of olivine and chromite, as well as on the crystallization temperatures based on Al-in-olivine geothermometry for komatiitic basalts from the Vetrenyi Belt are provided. The temperatures of the earliest stages of crystallization were approximately 1240 ± 25°C, which indicates the occurrence of water in the melt and is consistent with measured water contents of 0.4 ± 0.2 wt % H2O in the melt inclusions. However, during crystallization, the komatiitic basalt melt underwent degassing, resulting in mass crystallization of the system and a temperature rise by ~20°C due to the release of the latent heat of crystallization. The degassing of water from the melt suggests crystallization under surface conditions.
{"title":"Crystallization Temperatures of Komatiitic Basalts from the Vetrenyi Belt, Karelia Based on the Alumina Partition between Olivine and Chromite","authors":"E. V. Asafov, A. N. Koshlyakova, A. V. Sobolev, D. P. Tobelko, N. N. Koshlyakova, S. V. Mezhelovskaya","doi":"10.1134/s1028334x24601305","DOIUrl":"https://doi.org/10.1134/s1028334x24601305","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Archean–Proterozoic transition in the Earth’s history is marked by significant changes in the mantle dynamics and temperature regimes. A notable consequence is the disappearance of Al-depleted komatiites in the Late Archean and an almost complete absence of Archean-typical peridotitic komatiites since the Proterozoic. This work presents a study of the 2.41 Ga komatiitic basalts from the Vetrenyi Belt, dating back to the early Proterozoic. Unique data on the compositions of olivine and chromite, as well as on the crystallization temperatures based on Al-in-olivine geothermometry for komatiitic basalts from the Vetrenyi Belt are provided. The temperatures of the earliest stages of crystallization were approximately 1240 ± 25°C, which indicates the occurrence of water in the melt and is consistent with measured water contents of 0.4 ± 0.2 wt % H<sub>2</sub>O in the melt inclusions. However, during crystallization, the komatiitic basalt melt underwent degassing, resulting in mass crystallization of the system and a temperature rise by ~20°C due to the release of the latent heat of crystallization. The degassing of water from the melt suggests crystallization under surface conditions.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-27DOI: 10.1134/s1028334x24601196
R. F. Abdrakhmanov, V. N. Puchkov
Abstract
Natural studies of the South Urals hydromineral deposits, as well as the results of study of the ion and gaseous composition of underground waters, show that the liquid run-off from massive sulfide deposits of the region are promising serious deposits of secondary raw materials. The dump waters are mineral resources for rare metals, the contents of which are comparable with the average content of ores.
{"title":"Secondary Mineral Resources in Dump Waters of the South Urals","authors":"R. F. Abdrakhmanov, V. N. Puchkov","doi":"10.1134/s1028334x24601196","DOIUrl":"https://doi.org/10.1134/s1028334x24601196","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Natural studies of the South Urals hydromineral deposits, as well as the results of study of the ion and gaseous composition of underground waters, show that the liquid run-off from massive sulfide deposits of the region are promising serious deposits of secondary raw materials. The dump waters are mineral resources for rare metals, the contents of which are comparable with the average content of ores.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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