Pub Date : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-59-80
N. A. Kucheva
Subject. This paper is aimed at investigating the distribution of brachiopods across the stratotypes of the Lower Visean regional substages and formations, as well as of the Upper Visean Zhukovsky regional substage, which are presently located in the East Uralian and Magnitogorskian megazones of the Eastern Urals. Materials and methods. Brachiopods were one of the most numerous groups of benthic organisms inhabiting the Early Carboniferous marine basins now located in the eastern Urals. This paper presents information on the distribution of brachiopods across the carbonate and carbonate-terrigenous facies of the Middle (Pokrovskoe, Zhukovo, Smolino, Brod-Kljuchiki) and Southern (Nizhnyaya Gusikha, Verkhnyaya Kardailovka, Kipchak, Ust-Grekhovka and Khudolaz) Urals sections.Results. It is found that Delepinеа lebedevi, D. comoides, Ovatia markovskii and Composita sp. were the domineering species during the Early Visean period. The Ust-Grekhovsky time marked the appearance of migrant species, which resulted not only in a decrease in the proportion of Delepinеа and Ovatia but also significantly changed the entire structure of the local brachiopod communities. The evolutionary transformation of the Ovatia genus at the Ust-Grekhovsky–Zhukovsky time boundary led to the appearance of the Linoprotonia genus and subsequently to the Globosoproductus genus (the first representative of the Gigantoproductini). The Zhukovsky period was characterized by a continuing reorganization of the composition and structure of the communities, featuring a change in the dominant taxa. The Linoprotonia and Globosoproductus genera became widespread. Rare representatives of the Gigantoproductus, Datangia and Semiplanus genera appeared.Conclusions. A direct correlation between the diversity of brachiopod associations and abiotic factors is found. The most diverse associations represented by the taxa of several orders, including Gigantoproductini, inhabited shallow-water environments with carbonate sedimentation. The evolution of brachiopods over the Early Visean and Zhukovsky periods of the Late Visean was characterized by natural succession in the composition of genera and species, with the most significant alteration having occurred in the Ust-Grekhovsky and Zhukovsky periods.
{"title":"Distribution of brachiopods in the Lower Visean deposits in the Eastern Urals","authors":"N. A. Kucheva","doi":"10.24930/1681-9004-2019-19-1-59-80","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-59-80","url":null,"abstract":"Subject. This paper is aimed at investigating the distribution of brachiopods across the stratotypes of the Lower Visean regional substages and formations, as well as of the Upper Visean Zhukovsky regional substage, which are presently located in the East Uralian and Magnitogorskian megazones of the Eastern Urals. Materials and methods. Brachiopods were one of the most numerous groups of benthic organisms inhabiting the Early Carboniferous marine basins now located in the eastern Urals. This paper presents information on the distribution of brachiopods across the carbonate and carbonate-terrigenous facies of the Middle (Pokrovskoe, Zhukovo, Smolino, Brod-Kljuchiki) and Southern (Nizhnyaya Gusikha, Verkhnyaya Kardailovka, Kipchak, Ust-Grekhovka and Khudolaz) Urals sections.Results. It is found that Delepinеа lebedevi, D. comoides, Ovatia markovskii and Composita sp. were the domineering species during the Early Visean period. The Ust-Grekhovsky time marked the appearance of migrant species, which resulted not only in a decrease in the proportion of Delepinеа and Ovatia but also significantly changed the entire structure of the local brachiopod communities. The evolutionary transformation of the Ovatia genus at the Ust-Grekhovsky–Zhukovsky time boundary led to the appearance of the Linoprotonia genus and subsequently to the Globosoproductus genus (the first representative of the Gigantoproductini). The Zhukovsky period was characterized by a continuing reorganization of the composition and structure of the communities, featuring a change in the dominant taxa. The Linoprotonia and Globosoproductus genera became widespread. Rare representatives of the Gigantoproductus, Datangia and Semiplanus genera appeared.Conclusions. A direct correlation between the diversity of brachiopod associations and abiotic factors is found. The most diverse associations represented by the taxa of several orders, including Gigantoproductini, inhabited shallow-water environments with carbonate sedimentation. The evolution of brachiopods over the Early Visean and Zhukovsky periods of the Late Visean was characterized by natural succession in the composition of genera and species, with the most significant alteration having occurred in the Ust-Grekhovsky and Zhukovsky periods.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76518514","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-111-138
I. Melekestseva, V. Zaykov, G. Tret'yakov, K. Filippova, V. A. Kotlyarov
Subject. The article presents the results of study of Mechnikovskoe gold deposit associated with listvenites and beresites of the Miass region of the Southern Urals.Materials and methods. Materials were sampled during the field work of 2010– 2012. The chemical composition of rocks is analyzed by methods of classical chemistry (rock-forming oxides) and ICP MS (trace elements). The mineral composition is determined on an electron microscope with EDS.Results. The deposit is composed of tectonic sheets of serpentinites, carbonatized serpentinites and listvenites (sheet I), metadiabases and plagioclase metabasalts of the Irendyk Formation and beresites and volcanosedimentary rocks and metabasalts of the Karamalytash Formation (sheet II). In the central part of the deposit, the volcanic rocks are intruded by a dike of finegrained island-arc granites. Chromites of serpentinites are characterized (on average) by high Cr# (89) and low Mg# (29) values and low contents of Al2O3 (6.94 wt %) and MgO (5.5 wt %). Gold-bearing rocks include listvenites, beresites and carbonaceous shales. The major ore mineral is pyrite; accessory minerals are Au and Ag minerals, chalcopyrite, fahlores, galena, sphalerite, pyrrhotite, cubanite, vaesite, melonite, secondary copper sulfides, barite, rutile, monazite and xenotime. Gold of the deposit contains low Ag contents (3.52 wt %) and minor amount of Cu and Hg (<1 wt % in most analyses).Conclusions. The listvenites and beresites of the deposit were formed after ultramafic and mafic rocks, respectively. The discovery of gold in various rocks indicates that gold mineralization was deposited after the formation of the geological structure of the deposit. The source of gold was most likely related to a magmatic fluid.
{"title":"Geological structure and mineralogy of the Mechnikovskoe gold deposit, thе Southern Urals","authors":"I. Melekestseva, V. Zaykov, G. Tret'yakov, K. Filippova, V. A. Kotlyarov","doi":"10.24930/1681-9004-2019-19-1-111-138","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-111-138","url":null,"abstract":"Subject. The article presents the results of study of Mechnikovskoe gold deposit associated with listvenites and beresites of the Miass region of the Southern Urals.Materials and methods. Materials were sampled during the field work of 2010– 2012. The chemical composition of rocks is analyzed by methods of classical chemistry (rock-forming oxides) and ICP MS (trace elements). The mineral composition is determined on an electron microscope with EDS.Results. The deposit is composed of tectonic sheets of serpentinites, carbonatized serpentinites and listvenites (sheet I), metadiabases and plagioclase metabasalts of the Irendyk Formation and beresites and volcanosedimentary rocks and metabasalts of the Karamalytash Formation (sheet II). In the central part of the deposit, the volcanic rocks are intruded by a dike of finegrained island-arc granites. Chromites of serpentinites are characterized (on average) by high Cr# (89) and low Mg# (29) values and low contents of Al2O3 (6.94 wt %) and MgO (5.5 wt %). Gold-bearing rocks include listvenites, beresites and carbonaceous shales. The major ore mineral is pyrite; accessory minerals are Au and Ag minerals, chalcopyrite, fahlores, galena, sphalerite, pyrrhotite, cubanite, vaesite, melonite, secondary copper sulfides, barite, rutile, monazite and xenotime. Gold of the deposit contains low Ag contents (3.52 wt %) and minor amount of Cu and Hg (<1 wt % in most analyses).Conclusions. The listvenites and beresites of the deposit were formed after ultramafic and mafic rocks, respectively. The discovery of gold in various rocks indicates that gold mineralization was deposited after the formation of the geological structure of the deposit. The source of gold was most likely related to a magmatic fluid.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87773262","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-81-91
Andrey V. Zhuravlev
Subject.The article is aimed to evaluate of the conodont diversity dynamics at the species level in the Famennian – Serpukhovian interval.Materials and methods.The database compiled from the published and original data contains information on the stratigraphic ranges of 389 Famennian-Serpukhovian conodont species (https://1drv.ms/x/s!AvPFMTPLPc7T4nFU81CaO5UJ6nlw). Conodont zones compose the geochronological basis of the database. The conodont diversity, origination, extinction, and diversification were calculated. Dynamics of these parameters in the Late Devonian–Early Carboniferous was analyzed.Results.The Famennian-Serpukhovian conodonts demonstrate four cycles in the diversity: the early Famennian (triangularis-early postera zones), the late Famennian (late postera-praesulcata zones), the Tournaisian (sulcata-anchoralis zones), and the Visean-Serpukhovian (texanus-bollandensis zones). The cycles are separated by the low-diversity episodes. The highest diversity (80 species) is detected in the early and late marginifera zones (Famennian).Conclusions.The successive decreasing in diversity comprises interval from the late Famennian through Serpukhovian. The global events gave little influence on the conodont diversity except for the Frasnian/Famennian (about 70% conodont species became extinct) and Devonian/Carboniferous extinction events. Conodont diversity demonstrates weak dependence form the global sea level fluctuations. The transition from the green-house to ice-house climate at the beginning of the Carboniferous and successive changes in the marine ecosystems are considered as main probable cause of the decline in conodont diversity in the late Tournaisian-Serpukhovian.
{"title":"Dynamics of the conodont diversity in the Late Devonian–Early Carboniferous (Famennian–Serpukhovian)","authors":"Andrey V. Zhuravlev","doi":"10.24930/1681-9004-2019-19-1-81-91","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-81-91","url":null,"abstract":"Subject.The article is aimed to evaluate of the conodont diversity dynamics at the species level in the Famennian – Serpukhovian interval.Materials and methods.The database compiled from the published and original data contains information on the stratigraphic ranges of 389 Famennian-Serpukhovian conodont species (https://1drv.ms/x/s!AvPFMTPLPc7T4nFU81CaO5UJ6nlw). Conodont zones compose the geochronological basis of the database. The conodont diversity, origination, extinction, and diversification were calculated. Dynamics of these parameters in the Late Devonian–Early Carboniferous was analyzed.Results.The Famennian-Serpukhovian conodonts demonstrate four cycles in the diversity: the early Famennian (triangularis-early postera zones), the late Famennian (late postera-praesulcata zones), the Tournaisian (sulcata-anchoralis zones), and the Visean-Serpukhovian (texanus-bollandensis zones). The cycles are separated by the low-diversity episodes. The highest diversity (80 species) is detected in the early and late marginifera zones (Famennian).Conclusions.The successive decreasing in diversity comprises interval from the late Famennian through Serpukhovian. The global events gave little influence on the conodont diversity except for the Frasnian/Famennian (about 70% conodont species became extinct) and Devonian/Carboniferous extinction events. Conodont diversity demonstrates weak dependence form the global sea level fluctuations. The transition from the green-house to ice-house climate at the beginning of the Carboniferous and successive changes in the marine ecosystems are considered as main probable cause of the decline in conodont diversity in the late Tournaisian-Serpukhovian.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81154606","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-139-147
D. A. Zamiatina, V. V. Murzin
Research subject.This research study was aimed at investigating metasomatic minerals and ores in the Tamunier Deposit, which is located in the Northern Urals, at the Eastern side of the Tagil megazone within the Auerbach volcano-plutonic belt.Materials and methods.Well core samples were investigated using a complex of research methods, including optical and electron microscopy, X-ray spectral microanalysis, mineral geothermometry, thermobarogeochemistry (microthermometry, gas chromatography, determination of the salt composition of fluid inclusions in minerals) and isotope geochemistry (isotopes C, O, S, Sr, Pb).Results.A genetic model describing the formation of the Tamunier deposit was developed using the data obtained on its geological structure, mineral composition of metasomatites and ores, fluid formation mode, sources of ore matter and ore-bearing fluid. In the proposed model, the magmatogenic sodium chloride fluid carrying ore components and S is separated from the Auerbach complex at the depth of intrusion. Penetrating to the surface, this fluid interacts with the rocks of volcanic-sedimentary strata, thereby extracting a number of components, including CO2, S and Sr.Conclusion.Despite the presence of sulphide mineralization of hydrothermal-sedimentary genesis in the volcanogenic-sedimentary rock mass, the data obtained has allowed us to refer the gold-sulphide ores under study to magmatogenic-hydrothermal formations. The estimated P-T conditions (t= 100–370ºС andP= 0.4–0.6 kbar) and the shallow depth of the Tamunier field have shown its correspondence to the sub-epithermal level in the model of the porphyry-epithermal ore-magmatic system.
研究课题。本研究旨在研究位于乌拉尔北部的Tamunier矿床的交代矿物和矿石，该矿床位于Auerbach火山-深成带内的Tagil地层带东侧。材料和方法。采用光学和电子显微镜、x射线光谱显微分析、矿物地热测量、热压地球化学(显微测温、气相色谱、矿物流体包裹体盐组成测定)和同位素地球化学(同位素C、O、S、Sr、Pb)等综合研究方法对岩心样品进行了研究。利用其地质构造、交代岩和矿石矿物组成、流体形成模式、矿石物质来源和含矿流体等资料，建立了描述Tamunier矿床形成的成因模型。在该模型中，携带矿石组分和S的岩浆源氯化钠流体在侵入深部从Auerbach杂岩中分离出来。该流体渗透到地表后，与火山-沉积地层的岩石相互作用，从而提取出CO2、S和sr等组分。结论:尽管火山-沉积岩体中存在热液-沉积成因的硫化物成矿作用，但所获得的数据使我们能够将所研究的含金矿石归为岩浆-热液成因。估计的P-T条件(t= 100-370ºС， p = 0.4-0.6 kbar)和Tamunier油田的浅深度与斑岩-浅热液矿-岩浆体系模型中的亚浅热液层对应。
{"title":"The Tamunier gold deposit in the Northern Ural: Physicochemical formative conditions, ore and fluid sources, genesis","authors":"D. A. Zamiatina, V. V. Murzin","doi":"10.24930/1681-9004-2019-19-1-139-147","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-139-147","url":null,"abstract":"Research subject.This research study was aimed at investigating metasomatic minerals and ores in the Tamunier Deposit, which is located in the Northern Urals, at the Eastern side of the Tagil megazone within the Auerbach volcano-plutonic belt.Materials and methods.Well core samples were investigated using a complex of research methods, including optical and electron microscopy, X-ray spectral microanalysis, mineral geothermometry, thermobarogeochemistry (microthermometry, gas chromatography, determination of the salt composition of fluid inclusions in minerals) and isotope geochemistry (isotopes C, O, S, Sr, Pb).Results.A genetic model describing the formation of the Tamunier deposit was developed using the data obtained on its geological structure, mineral composition of metasomatites and ores, fluid formation mode, sources of ore matter and ore-bearing fluid. In the proposed model, the magmatogenic sodium chloride fluid carrying ore components and S is separated from the Auerbach complex at the depth of intrusion. Penetrating to the surface, this fluid interacts with the rocks of volcanic-sedimentary strata, thereby extracting a number of components, including CO2, S and Sr.Conclusion.Despite the presence of sulphide mineralization of hydrothermal-sedimentary genesis in the volcanogenic-sedimentary rock mass, the data obtained has allowed us to refer the gold-sulphide ores under study to magmatogenic-hydrothermal formations. The estimated P-T conditions (t= 100–370ºС andP= 0.4–0.6 kbar) and the shallow depth of the Tamunier field have shown its correspondence to the sub-epithermal level in the model of the porphyry-epithermal ore-magmatic system.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72550445","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-30-47
A. Fazliakhmetov
Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.
{"title":"Geochemical features and formation conditions of Early-Devonian cherty-argillaceous shales and the underlying basalts in the Ishkildino section (eastern slope of the Southern Urals)","authors":"A. Fazliakhmetov","doi":"10.24930/1681-9004-2019-19-1-30-47","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-30-47","url":null,"abstract":"Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"138 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79817092","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-5-29
Yu. G. Tsekhovskii, В. А. Bogatyrev, V. V. Zhukov
Research subject. The inner structure, composition, and genesis of the poorly studied formation of weathering crusts are studied with reference to peneplaned platform territories in Kazakhstan and Siberia during the Cretaceous-Paleogene boundary epoch. This formation hosts many valuable minerals, such as bauxite, iron ores, refractory clays, etc., thereby attracting much research attention. Materials and methods. The results were obtained following a series of long-term studies and a review of available data recently obtained on the weathering crust formation in the territories of Kazakhstan and Siberia. The methods of lithological facies and formation analysis were used, along with the separate studies of the eluvial material – weathering crusts in erosion areas and intra-formation weathering horizons in accumulation areas. Results. The weathering crust formation in the study area is shown to comprise two kinds of rock mass: siliceous-kaolinite ones forming erosion-tectonic depressions and kaolinite-bauxite ones forming karst depressions. The inner structure, composition, and genesis of both rock mass units are studied in detail, with all their sedimentation stages being analyzed. The sedimentation process is traced from the preparation of the material in weathering crusts at erosion areas to the deposition of this material and its post-sedimentation transformations (mostly with the involvement of subaerial diagenesis) in depressions. Detailed information is presented on subaerial diagenesis, which deserves further studies. Conclusions. This publication is the frst to present detailed information on the inner structure, composition and genesis of the ancient formation of weathering crusts produced in hot humid climate on peneplaned land territories. It is confrmed that the processes underpinning this formation – starting with the preparation of the material and ending with its accumulation in depressions – were different from those typical of modern orogenic environments. This conclusion extends the current understanding of the forms and nature of ancient lithogenetic processes.
{"title":"Lithogenesis on peneplaned сontinented platform of Kazakhstan and Siberia during the Cretaceous-Paleogene boundary epoch","authors":"Yu. G. Tsekhovskii, В. А. Bogatyrev, V. V. Zhukov","doi":"10.24930/1681-9004-2019-19-1-5-29","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-5-29","url":null,"abstract":"Research subject. The inner structure, composition, and genesis of the poorly studied formation of weathering crusts are studied with reference to peneplaned platform territories in Kazakhstan and Siberia during the Cretaceous-Paleogene boundary epoch. This formation hosts many valuable minerals, such as bauxite, iron ores, refractory clays, etc., thereby attracting much research attention. Materials and methods. The results were obtained following a series of long-term studies and a review of available data recently obtained on the weathering crust formation in the territories of Kazakhstan and Siberia. The methods of lithological facies and formation analysis were used, along with the separate studies of the eluvial material – weathering crusts in erosion areas and intra-formation weathering horizons in accumulation areas. Results. The weathering crust formation in the study area is shown to comprise two kinds of rock mass: siliceous-kaolinite ones forming erosion-tectonic depressions and kaolinite-bauxite ones forming karst depressions. The inner structure, composition, and genesis of both rock mass units are studied in detail, with all their sedimentation stages being analyzed. The sedimentation process is traced from the preparation of the material in weathering crusts at erosion areas to the deposition of this material and its post-sedimentation transformations (mostly with the involvement of subaerial diagenesis) in depressions. Detailed information is presented on subaerial diagenesis, which deserves further studies. Conclusions. This publication is the frst to present detailed information on the inner structure, composition and genesis of the ancient formation of weathering crusts produced in hot humid climate on peneplaned land territories. It is confrmed that the processes underpinning this formation – starting with the preparation of the material and ending with its accumulation in depressions – were different from those typical of modern orogenic environments. This conclusion extends the current understanding of the forms and nature of ancient lithogenetic processes.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86912462","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 : 2019-03-17DOI: 10.24930/1681-9004-2019-19-1-162-175
K. Ivanov, N. Kostrov, A. Stepanov
Research subject. The deep structure of the Yugan-Koltogor zone located in West Siberia was investigated with the purpose of detecting prospective oil and gas bearing areas.Materials and methods. The methods of lineament extraction and the computer modelling of rock density were employed. Lineament extraction was conducted on the basis of geophysical data, including detailed (1 : 200 000) maps of anomalous magnetic and gravity fields. In order to detect faults, telemetering methods were used, along with the results of studies conducted to investigate core materials from wells in the region. The modelling of the deep structure of the pre-Jurassic basement was performed on the basis of its geological map by solving a direct problem while fitting geological body densities.Results. Six largest faults of the Yugan-Koltogor zone identified on the geological map by a special sign “deep faults and regional schistosity zones” are of particular interest as possible oil bearing areas.Conclusions. The modelling of the deep structure of the pre-Jurassic basement of the West Siberian Platform has shown the granite decompaction areas of the Yugan zone to be highly promising in terms of oil and gas deposits.
{"title":"Tectonics and deep structure of Yugan-Koltogor zone of West Siberia Platform foundation","authors":"K. Ivanov, N. Kostrov, A. Stepanov","doi":"10.24930/1681-9004-2019-19-1-162-175","DOIUrl":"https://doi.org/10.24930/1681-9004-2019-19-1-162-175","url":null,"abstract":"Research subject. The deep structure of the Yugan-Koltogor zone located in West Siberia was investigated with the purpose of detecting prospective oil and gas bearing areas.Materials and methods. The methods of lineament extraction and the computer modelling of rock density were employed. Lineament extraction was conducted on the basis of geophysical data, including detailed (1 : 200 000) maps of anomalous magnetic and gravity fields. In order to detect faults, telemetering methods were used, along with the results of studies conducted to investigate core materials from wells in the region. The modelling of the deep structure of the pre-Jurassic basement was performed on the basis of its geological map by solving a direct problem while fitting geological body densities.Results. Six largest faults of the Yugan-Koltogor zone identified on the geological map by a special sign “deep faults and regional schistosity zones” are of particular interest as possible oil bearing areas.Conclusions. The modelling of the deep structure of the pre-Jurassic basement of the West Siberian Platform has shown the granite decompaction areas of the Yugan zone to be highly promising in terms of oil and gas deposits.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83742491","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 : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-859-869
L. Y. Kabanova, Vsevolod N. Anfilogov, M. A. Igumentseva, V. A. Kotlyarov
Object of study. The article presents of the petrographic study results of the garnet-containing rocks from the Ufaleiskii complex, located on the border of the Ufaleyskii metamorphic gneiss-amphibolite block with the Main Ural Fault (GUR). Methods. Petrographic studies were conducted using a polarizing microscope Axiolab ZS и Olimpus BX 51. Chemical composition of garnets is performed on the raster electron microscope of the РЭММА-202М with an energy dispersive spectrometer LZ-5. Results. Investigations made it possible to distinguish two types of garnet-containing rocks. One type, in which garnet was formed after amphibole (amphibolites and gornbendites), and the second one, in which garnet is the primary mineral (metamorphic schists). Zoisite and chlorite are formed in rocks of the first type together with granate. CaO, MgO, FeO and Al2O3 were extracted from amphibole, in the process of crystallization of garnet, some of these components went to form zoisite and chlorite, and the released silica formed quartz. Garnet grains in these rocks are 64–68% composed of almandine. In the rocks of the second type, represented by biotite-hornblende, biotite-chlorite-quartz and double-mica schists, garnet is the primary mineral formed from the original rocks in the process of progressive metamorphism. The composition of the garnet in these rocks correlates with the composition of the original rock. Conclusion. A complex of garnet-containing rocks with a high content of granulated quartz may be of interest as a raw material for obtaining pure quartz concentrates. The paper presents the results of a detailed petrographic study of all types of rocks of the complex and discusses possible options for their genesis.
{"title":"Petrography of garnet-containing rocks of the Ufalei block, the Southern Urals","authors":"L. Y. Kabanova, Vsevolod N. Anfilogov, M. A. Igumentseva, V. A. Kotlyarov","doi":"10.24930/1681-9004-2018-18-6-859-869","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-859-869","url":null,"abstract":"Object of study. The article presents of the petrographic study results of the garnet-containing rocks from the Ufaleiskii complex, located on the border of the Ufaleyskii metamorphic gneiss-amphibolite block with the Main Ural Fault (GUR). Methods. Petrographic studies were conducted using a polarizing microscope Axiolab ZS и Olimpus BX 51. Chemical composition of garnets is performed on the raster electron microscope of the РЭММА-202М with an energy dispersive spectrometer LZ-5. Results. Investigations made it possible to distinguish two types of garnet-containing rocks. One type, in which garnet was formed after amphibole (amphibolites and gornbendites), and the second one, in which garnet is the primary mineral (metamorphic schists). Zoisite and chlorite are formed in rocks of the first type together with granate. CaO, MgO, FeO and Al2O3 were extracted from amphibole, in the process of crystallization of garnet, some of these components went to form zoisite and chlorite, and the released silica formed quartz. Garnet grains in these rocks are 64–68% composed of almandine. In the rocks of the second type, represented by biotite-hornblende, biotite-chlorite-quartz and double-mica schists, garnet is the primary mineral formed from the original rocks in the process of progressive metamorphism. The composition of the garnet in these rocks correlates with the composition of the original rock. Conclusion. A complex of garnet-containing rocks with a high content of granulated quartz may be of interest as a raw material for obtaining pure quartz concentrates. The paper presents the results of a detailed petrographic study of all types of rocks of the complex and discusses possible options for their genesis.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72756515","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 : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-839-858
K. Ivanov, S. Berzin, N. V. Vakhrusheva, N. Kostrov, O. Pogromskaya
Subject of the study.We have carried out an additional exploration on petrography, petrochemistry, geochemistry, geochronology and biostratigraphy of rock complexes of the Yugansk-Koltogorsk (central part of West Siberia).Materials and methods.The materials are core samples from wells that penetrated the Pre-Jurassic basement rock complexes The used methods are as follows: X-ray spectrum microanalysis (Cameca SX 100, JEOL-733 Superprobe); the silicate analysis of the rocks (СРМ-18 and EDX-100); mass-spectroscopy with inductively coupled plasma (ICP-MS) (ELAN-9000 and Element2); zircons were analysed with a high resolution ionic microprobe SHRIMP-II (U-Pb); Ar-Ar dating was carried out by Micromass 5400; biostratigraphy, petrochemestry.Results.A geological map of Yugan-Koltogor zone of the central part of West-Siberian plate in a scale 1:500 000 was created. The map is a set of informational geological, geophysical and other layers. It was established that age of granites is Early Permian, the basalts of the rift zone began to form 268.4 ± 7.5 Ma ago (Ar-Ar). Conclusions. Volcanism in the axial rift zones of the West-Siberian megabasin basement began earlier than it is supposed before our study and significantly earlier of that of trap basalts of Siberian platform.
研究对象。我们对尤甘斯克-科尔托戈尔斯克(西西伯利亚中部)岩石复合体的岩石学、岩石化学、地球化学、地质年代学和生物地层学进行了进一步的勘探。材料和方法。材料为钻穿前侏罗统基底杂岩井的岩心样品，使用的方法如下:x射线光谱显微分析(Cameca SX 100, JEOL-733 Superprobe);岩石的硅酸盐分析(СРМ-18和EDX-100);电感耦合等离子体质谱(ICP-MS) (ELAN-9000和Element2);采用高分辨率离子探针SHRIMP-II (U-Pb)对锆石进行分析;用Micromass 5400进行Ar-Ar测年;结果绘制了西西伯利亚板块中部尤干—科尔托戈尔带1:50万比例尺的地质图。该地图是一组信息地质，地球物理和其他层。确定花岗岩年龄为早二叠世，裂谷带玄武岩开始形成于268.4±7.5 Ma (Ar-Ar)。结论。西西伯利亚巨型基底轴向裂谷带的火山活动开始时间早于研究前的估计，西伯利亚台地圈闭玄武岩的火山活动开始时间明显早于研究前的估计。
{"title":"Geological structure of the Pre-jurassic basement of the Yugansk-Koltogorsk zone of the West Siberia","authors":"K. Ivanov, S. Berzin, N. V. Vakhrusheva, N. Kostrov, O. Pogromskaya","doi":"10.24930/1681-9004-2018-18-6-839-858","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-839-858","url":null,"abstract":"Subject of the study.We have carried out an additional exploration on petrography, petrochemistry, geochemistry, geochronology and biostratigraphy of rock complexes of the Yugansk-Koltogorsk (central part of West Siberia).Materials and methods.The materials are core samples from wells that penetrated the Pre-Jurassic basement rock complexes The used methods are as follows: X-ray spectrum microanalysis (Cameca SX 100, JEOL-733 Superprobe); the silicate analysis of the rocks (СРМ-18 and EDX-100); mass-spectroscopy with inductively coupled plasma (ICP-MS) (ELAN-9000 and Element2); zircons were analysed with a high resolution ionic microprobe SHRIMP-II (U-Pb); Ar-Ar dating was carried out by Micromass 5400; biostratigraphy, petrochemestry.Results.A geological map of Yugan-Koltogor zone of the central part of West-Siberian plate in a scale 1:500 000 was created. The map is a set of informational geological, geophysical and other layers. It was established that age of granites is Early Permian, the basalts of the rift zone began to form 268.4 ± 7.5 Ma ago (Ar-Ar). Conclusions. Volcanism in the axial rift zones of the West-Siberian megabasin basement began earlier than it is supposed before our study and significantly earlier of that of trap basalts of Siberian platform.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84421580","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 : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-819-838
G. Mizens, R. Sungatullin, G. Sungatullina, B. Gareev, G. Batalin, F. F. Sadriev
Object.Geochemical features of rocks from the Dal’ny Tulkas and Mechetlino sections located in the southern part of the West Urals foredeep are considered and are offered as International Standards for the global correlation (GSSP) of the lower boundaries of the Artinskian and Kungurian stages.Materials and methods.The content of rock-forming oxides and other components were studied for 15 and 20 samples of carbonate, clay and sandy rocks respectively in the sections of Dalnii Tyulkas and Mechetlino. The determination of the chemical composition of rocks was performed using a wave-dispersive X-ray fluorescence spectrometer S8 Tiger (Bruker, Germany). Results. The lithological characteristics of the sections, the content of oxides in mudstones and limestones of the boundary Sakmarian-Artinskian and of the boundary ArtinskianKungurian are taken. Mudstones of different stage are almost identical in average contents of the main components, whereas limestones have some differences. Correlative connections of oxides are analyzed and conclusions about mineral composition of rocks are made. Using the petrochemical modules and diagrams, it was established that the clay rocks in considered sections have mainly a hydromica composition. Based on the analysis of the indices of chemical weathering CIA, it is shown that the climate in the Cisuralian Epoch was predominantly arid. The tectonic environment of forming demolition sources, presumably corresponded to the active and passive margins of the continents.Conclusions.The main lithochemical characteristics of the rocks of the two sections under consideration are somewhat different, however, the boundaries of the stratigraphic subdivisions of each of them are virtually indistinguishable by lithochemical parameters, which may indicate the benefit of the continuity of sedimentation at the borders of centuries of the Cisuralian Epoch in this region. The conditions of sedimentation and the nature of eroded rocks in the area of demolition remained relatively constant. This is a positive point when looking the sections as International Standards for the global correlation (GSSP) reference objects – “golden nails”.
{"title":"Reference sections OF Cisuralian Series (Permian System): geochemical features","authors":"G. Mizens, R. Sungatullin, G. Sungatullina, B. Gareev, G. Batalin, F. F. Sadriev","doi":"10.24930/1681-9004-2018-18-6-819-838","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-819-838","url":null,"abstract":"Object.Geochemical features of rocks from the Dal’ny Tulkas and Mechetlino sections located in the southern part of the West Urals foredeep are considered and are offered as International Standards for the global correlation (GSSP) of the lower boundaries of the Artinskian and Kungurian stages.Materials and methods.The content of rock-forming oxides and other components were studied for 15 and 20 samples of carbonate, clay and sandy rocks respectively in the sections of Dalnii Tyulkas and Mechetlino. The determination of the chemical composition of rocks was performed using a wave-dispersive X-ray fluorescence spectrometer S8 Tiger (Bruker, Germany). Results. The lithological characteristics of the sections, the content of oxides in mudstones and limestones of the boundary Sakmarian-Artinskian and of the boundary ArtinskianKungurian are taken. Mudstones of different stage are almost identical in average contents of the main components, whereas limestones have some differences. Correlative connections of oxides are analyzed and conclusions about mineral composition of rocks are made. Using the petrochemical modules and diagrams, it was established that the clay rocks in considered sections have mainly a hydromica composition. Based on the analysis of the indices of chemical weathering CIA, it is shown that the climate in the Cisuralian Epoch was predominantly arid. The tectonic environment of forming demolition sources, presumably corresponded to the active and passive margins of the continents.Conclusions.The main lithochemical characteristics of the rocks of the two sections under consideration are somewhat different, however, the boundaries of the stratigraphic subdivisions of each of them are virtually indistinguishable by lithochemical parameters, which may indicate the benefit of the continuity of sedimentation at the borders of centuries of the Cisuralian Epoch in this region. The conditions of sedimentation and the nature of eroded rocks in the area of demolition remained relatively constant. This is a positive point when looking the sections as International Standards for the global correlation (GSSP) reference objects – “golden nails”. ","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80754181","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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