Pub Date : 2023-01-11DOI: 10.47765/0869-5997-2022-10022
A. Chernykh, Alexey V. Okulov, S. Kryazhev, Irina V. Arsentieva
In this work, we consider the geological settings, mineralogical composition and age of rocks and ores, as well as regularities in the formation of gold mineralization of the Shamansky ore cluster, which is one of the most prospective ore clusters in the Altai-Sayan mineragenic province. It is shown that the cluster has a complex fold-block structure. The rocks are characterized by intense folded and discontinuous dislocations. We identified the area of the reatest deformations, where the known prospective signs of gold mineralization are concentrated. Two morphological types of gold-sulfidequartz ores have been distinguished: veins and pyritequartz-sericite-ankerite metasomatite. We characterized the composition of gold and its morphological features. Sulfur isotope data of sulfides from gold-bearing quartz veins predominantly have values of δ34S from +3.7 to+6.5 ‰ that indicate their hydrothermal-sedimentary origin. 40Ar/39Ar isotope-geochronological data on sericite from gold-bearing quartz shows the age of 359.5 ± 5.5 Ma testifying to the Late Devonian-Early Carboniferous stage of the formation of gold-sulfide-quartz veins. A comparison of geological, metallogenic, mineralogical-geochemical and isotope-geochronological data allowed us to conclude that the gold mineralization of the Shamansky cluster belongs to the orogenic type. According to the model of formation, gold mineralization occurred in three stages: ore-preparation islandarc (540-520 Ma), main ore orogenic-1 accretion-collisional (510-450 Ma), and additional ore orogenic-2 transpressional-collisional (380-345 Ma).
{"title":"Geological structure and gold prospectivity of the Shamansky ore cluster of the Altai-Sayan folded region (Republic of Khakassia)","authors":"A. Chernykh, Alexey V. Okulov, S. Kryazhev, Irina V. Arsentieva","doi":"10.47765/0869-5997-2022-10022","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10022","url":null,"abstract":"In this work, we consider the geological settings, mineralogical composition and age of rocks and ores, as well as regularities in the formation of gold mineralization of the Shamansky ore cluster, which is one of the most prospective ore clusters in the Altai-Sayan mineragenic province. It is shown that the cluster has a complex fold-block structure. The rocks are characterized by intense folded and discontinuous dislocations. We identified the area of the reatest deformations, where the known prospective signs of gold mineralization are concentrated. Two morphological types of gold-sulfidequartz ores have been distinguished: veins and pyritequartz-sericite-ankerite metasomatite. We characterized the composition of gold and its morphological features. Sulfur isotope data of sulfides from gold-bearing quartz veins predominantly have values of δ34S from +3.7 to+6.5 ‰ that indicate their hydrothermal-sedimentary origin. 40Ar/39Ar isotope-geochronological data on sericite from gold-bearing quartz shows the age of 359.5 ± 5.5 Ma testifying to the Late Devonian-Early Carboniferous stage of the formation of gold-sulfide-quartz veins. A comparison of geological, metallogenic, mineralogical-geochemical and isotope-geochronological data allowed us to conclude that the gold mineralization of the Shamansky cluster belongs to the orogenic type. According to the model of formation, gold mineralization occurred in three stages: ore-preparation islandarc (540-520 Ma), main ore orogenic-1 accretion-collisional (510-450 Ma), and additional ore orogenic-2 transpressional-collisional (380-345 Ma).","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81186608","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 : 2023-01-11DOI: 10.47765/0869-5997-2022-10023
Galym Zh. Nurzhanov, V. V. Kuznetsov, Pavel A. Nicenko, N. G. Kudryavtseva, Tatiana P. Kuznetsova, Mergen M. Murzagulov
The article considers the geological features and ore composition of the Dyusembay Central (Sayakhat) leadzinc deposit in the Karsakpai metallogenic complex in the Central Kazakhstan. Historically, the complex was considered industrially significant in terms of iron ores, rather than of lead, zinc, and copper. It is shown that the ore deposit is composed of tuffaceous, silty-sandstone, carbonaceous-terrigenous (ore-hosting), terrigenous, and volcanogenic rocks assigned to the lower subformation of the Zhilandysai Formation of the Upper Proterozoic. The subvolcanic rocks identified and outlined in the area of the ore deposit belong to vent volcanic facies and are represented by felsic automagmatic breccias. All the rock complexes developed within the deposit have undergone multiple alterations: the regional, postvolcanic, contact, and hydrothermal (near-ore) ones. Commercial ores are represented by veinlet-disseminated sulfide mineralization in carbonaceous mudstones and silty sandstones, regionally and metasomatically altered to varying degrees. The ore bodies are composed of heterogeneous mineral assemblages corresponding to various stages and phases of the ore formation. The composition and structural and textural features of the ores reflect the long and complicated history of their formation. It is concluded that this ore deposit belongs to a new formational type of veinlet-disseminated stratified lead-zinc deposits localized in black shale sequences, with a significant role of volcanic activity and regional metamorphism, and is a remobilized SEDEX-type ore deposit.
{"title":"Geological features and genesis of the Dyusembay Central (Sayakhat) ore deposit","authors":"Galym Zh. Nurzhanov, V. V. Kuznetsov, Pavel A. Nicenko, N. G. Kudryavtseva, Tatiana P. Kuznetsova, Mergen M. Murzagulov","doi":"10.47765/0869-5997-2022-10023","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10023","url":null,"abstract":"The article considers the geological features and ore composition of the Dyusembay Central (Sayakhat) leadzinc deposit in the Karsakpai metallogenic complex in the Central Kazakhstan. Historically, the complex was considered industrially significant in terms of iron ores, rather than of lead, zinc, and copper. It is shown that the ore deposit is composed of tuffaceous, silty-sandstone, carbonaceous-terrigenous (ore-hosting), terrigenous, and volcanogenic rocks assigned to the lower subformation of the Zhilandysai Formation of the Upper Proterozoic. The subvolcanic rocks identified and outlined in the area of the ore deposit belong to vent volcanic facies and are represented by felsic automagmatic breccias. All the rock complexes developed within the deposit have undergone multiple alterations: the regional, postvolcanic, contact, and hydrothermal (near-ore) ones. Commercial ores are represented by veinlet-disseminated sulfide mineralization in carbonaceous mudstones and silty sandstones, regionally and metasomatically altered to varying degrees. The ore bodies are composed of heterogeneous mineral assemblages corresponding to various stages and phases of the ore formation. The composition and structural and textural features of the ores reflect the long and complicated history of their formation. It is concluded that this ore deposit belongs to a new formational type of veinlet-disseminated stratified lead-zinc deposits localized in black shale sequences, with a significant role of volcanic activity and regional metamorphism, and is a remobilized SEDEX-type ore deposit.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82469017","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 : 2023-01-11DOI: 10.47765/0869-5997-2022-10024
Tatiana V. Seravina, S. Kuznetsova, Lyudmila K. Filatova, Alexander I. Donets, Viktor D. Konkin
The Tushkanikhinskoye deposit is confined to the Devonian basalt-bearing rhyolite calcareous-siliceousterrigenous formation, which is represented by sedimentary, volcano-sedimentary, sedimentary-volcanogenic, pyroclastic, volcanic rocks of felsic and basic composition, as well as their subvolcanic equivalents. Felsic volcanogenic rocks show signs of ignimbrites. Primary pyrite-polymetallic ores with an uneven distribution of the main sulfi sphalerite, pyrite, galena, and chalcopyrite have been identified. The presence of collomorphic, framboidal and granoblastic pyrite in the ores, as well as the presence of sedimentary breccia ores with sulfi in clasts and matrix advocates for the hydrothermal-sedimentary origin of the ores. The ore bodies represent destroyed hydrothermal structures, so-called "ore hills".
{"title":"Localization features of pyrite-polymetallic oresof the Tushkanikhinskoye deposit (Rudny Altai)","authors":"Tatiana V. Seravina, S. Kuznetsova, Lyudmila K. Filatova, Alexander I. Donets, Viktor D. Konkin","doi":"10.47765/0869-5997-2022-10024","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10024","url":null,"abstract":"The Tushkanikhinskoye deposit is confined to the Devonian basalt-bearing rhyolite calcareous-siliceousterrigenous formation, which is represented by sedimentary, volcano-sedimentary, sedimentary-volcanogenic, pyroclastic, volcanic rocks of felsic and basic composition, as well as their subvolcanic equivalents. Felsic volcanogenic rocks show signs of ignimbrites. Primary pyrite-polymetallic ores with an uneven distribution of the main sulfi sphalerite, pyrite, galena, and chalcopyrite have been identified. The presence of collomorphic, framboidal and granoblastic pyrite in the ores, as well as the presence of sedimentary breccia ores with sulfi in clasts and matrix advocates for the hydrothermal-sedimentary origin of the ores. The ore bodies represent destroyed hydrothermal structures, so-called \"ore hills\".","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91238271","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 : 2023-01-11DOI: 10.47765/0869-5997-2022-10020
Aslambek A. Germakhanov, A. Chernykh, M. M. Girfanov, Valery A. Istomin, Andrey S. Svatkov
The status and prospects of the mineral resource base of solid minerals of the Bolivarian Republic of Venezuela, as well as possibilities for developing the RussianVenezuelan cooperation in the field of geology and mineral resource management are considered. Venezuela has world's largest oil reserves and a wide range of solid minerals (gold, diamonds, nickel, bauxite, iron ores, tantalum and niobium, other rare and base metals, various industrial minerals), which resource base retains significant growth prospects. The main direction of intensification of the mining industry is associated with implementation of a large-scale Governmental program for the geological study and development of the Orinoco Mining Belt in the northern Bolivar State. Within the belt, a number of commercial mineral deposits and much significant potential resources of the solid minerals have been identified and localized, requiring a modern reassessment in order to increase their investment attractiveness for major foreign mining companies. A prominent place in the development of the mineral resource complex of Venezuela can be occupied by Russian mining companies in cooperation with organizations of the Russian Geological Survey.
{"title":"The state and prospects of development of the mineral resource base of solid minerals of the Bolivarian Republic of Venezuela","authors":"Aslambek A. Germakhanov, A. Chernykh, M. M. Girfanov, Valery A. Istomin, Andrey S. Svatkov","doi":"10.47765/0869-5997-2022-10020","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10020","url":null,"abstract":"The status and prospects of the mineral resource base of solid minerals of the Bolivarian Republic of Venezuela, as well as possibilities for developing the RussianVenezuelan cooperation in the field of geology and mineral resource management are considered. Venezuela has world's largest oil reserves and a wide range of solid minerals (gold, diamonds, nickel, bauxite, iron ores, tantalum and niobium, other rare and base metals, various industrial minerals), which resource base retains significant growth prospects. The main direction of intensification of the mining industry is associated with implementation of a large-scale Governmental program for the geological study and development of the Orinoco Mining Belt in the northern Bolivar State. Within the belt, a number of commercial mineral deposits and much significant potential resources of the solid minerals have been identified and localized, requiring a modern reassessment in order to increase their investment attractiveness for major foreign mining companies. A prominent place in the development of the mineral resource complex of Venezuela can be occupied by Russian mining companies in cooperation with organizations of the Russian Geological Survey.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84106375","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 : 2023-01-11DOI: 10.47765/0869-5997-2022-10021
A. Kremenetsky, I. G. Spiridonov, Alexey G. Pilitsyn, L. I. Veremeeva
The project of organizing mineral-and-energy clusters with spatial conjugation of deposits of solid minerals (SM) and hydrocarbons (HC) localized on the continental margin and shelf of the Arctic zone of the Russian Federation is substantiated. Four clusters of the kind are characterized, i.e.: Murmansk-Barents, YamalNorilsk, Lena-Laptev Sea and Northeast-Chukotka, with the corresponding characteristics of the SM and HC resource bases, as well as substantiation of the bedrock gold and porphyry copper prospective areas in the Northeast-Chukotka cluster.An example of prediction and localization of the HC accumulations in the deep-water part of the Arctic Basin outside the 200-mile zone of the Russian shelf is considered. Geological and morphostructural evidence of the epicontinental nature of the bottom of the Amerasian and Eurasian basins is presented as a criterion for substantiating Russia's right to expand the outer boundary of the continental shelf.
{"title":"Mineral-and-energy clusters of the Russian Аrctic and prospects for expanding the outer boundary of its continental shelf","authors":"A. Kremenetsky, I. G. Spiridonov, Alexey G. Pilitsyn, L. I. Veremeeva","doi":"10.47765/0869-5997-2022-10021","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10021","url":null,"abstract":"The project of organizing mineral-and-energy clusters with spatial conjugation of deposits of solid minerals (SM) and hydrocarbons (HC) localized on the continental margin and shelf of the Arctic zone of the Russian Federation is substantiated. Four clusters of the kind are characterized, i.e.: Murmansk-Barents, YamalNorilsk, Lena-Laptev Sea and Northeast-Chukotka, with the corresponding characteristics of the SM and HC resource bases, as well as substantiation of the bedrock gold and porphyry copper prospective areas in the Northeast-Chukotka cluster.An example of prediction and localization of the HC accumulations in the deep-water part of the Arctic Basin outside the 200-mile zone of the Russian shelf is considered. Geological and morphostructural evidence of the epicontinental nature of the bottom of the Amerasian and Eurasian basins is presented as a criterion for substantiating Russia's right to expand the outer boundary of the continental shelf.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77408648","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}
Errors arising in the exploration of ore deposits can be divided into two groups: errors in determining specific quantitative characteristics of mineralization (average thickness, grade, density) and errors in identifying the conditions of occurrence, shape and structure of ore clusters. This article discusses the reasons for the non-confirmation of explored reserves for individual blocks of ore bodies of the Charmitan gold deposit. The calculated parameters and ore and metal reserves are compared in the framework of proven reserves for four ore bodies with unconfirmed reserves. The main discrepancies in ore and metal reserves, non-confirmation of body thicknesses and gold grades, as well as a complex of factors are considered: the density of the exploration network, and statistical and spatial variability of useful components.
{"title":"Reasons for non-confirmation of explored reserves at the Charmitan gold deposit","authors":"Avazbek Okhunov, Valentina Zimalina, Nafisa Rakhmonova, Zhavokhirzhon Mukhammedov","doi":"10.47765/0869-5997-2022-10016","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10016","url":null,"abstract":"Errors arising in the exploration of ore deposits can be divided into two groups: errors in determining specific quantitative characteristics of mineralization (average thickness, grade, density) and errors in identifying the conditions of occurrence, shape and structure of ore clusters. This article discusses the reasons for the non-confirmation of explored reserves for individual blocks of ore bodies of the Charmitan gold deposit. The calculated parameters and ore and metal reserves are compared in the framework of proven reserves for four ore bodies with unconfirmed reserves. The main discrepancies in ore and metal reserves, non-confirmation of body thicknesses and gold grades, as well as a complex of factors are considered: the density of the exploration network, and statistical and spatial variability of useful components.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"144 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80402542","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 : 2022-11-15DOI: 10.47765/0869-5997-2022-10018
Ksenia O. Shishkanova, V. Okrugin, Tatyana Philosofova
The Mutnovskoe deposit is one of the largest and most prospective ore deposits in South Kamchatka. The northern and southern flanks within the main veining zone Opredelyayushchaya, composed of low-sulfi (goldsilver) and sulfide-polymetallic (gold-silver-polymetallic) types of ores, respectively, are distinguished. The paper presents the results of the complex mineralogical and geochemical studies of the gold-silver-polymetallic ores of the southern flank of the deposit. Features of textures and structures, mineral, chemical compositions and genesis of the ores, as well forms of precious and base metals occurrences are shown. Typomorphic features of pyrite, sphalerite, galena, chalcopyrite, tennantite-tetrahedrite, Au, Ag, Pb and Bi tellurides, native gold, Bi, Se and Ag sulfosalts are characterized. The pyrite-sphaleritequartz, sphalerite-galena-quartz, and chalcopyrite-tennantite-tetrahedrite mineral associations are distinguished. The temperatures and composition of ore-forming solutions are shown.
{"title":"Mineralogy of the ores on the southern flank of the Mutnovskoe gold-silver-polymetallic deposit (Southern Kamchatka)","authors":"Ksenia O. Shishkanova, V. Okrugin, Tatyana Philosofova","doi":"10.47765/0869-5997-2022-10018","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10018","url":null,"abstract":"The Mutnovskoe deposit is one of the largest and most prospective ore deposits in South Kamchatka. The northern and southern flanks within the main veining zone Opredelyayushchaya, composed of low-sulfi (goldsilver) and sulfide-polymetallic (gold-silver-polymetallic) types of ores, respectively, are distinguished. The paper presents the results of the complex mineralogical and geochemical studies of the gold-silver-polymetallic ores of the southern flank of the deposit. Features of textures and structures, mineral, chemical compositions and genesis of the ores, as well forms of precious and base metals occurrences are shown. Typomorphic features of pyrite, sphalerite, galena, chalcopyrite, tennantite-tetrahedrite, Au, Ag, Pb and Bi tellurides, native gold, Bi, Se and Ag sulfosalts are characterized. The pyrite-sphaleritequartz, sphalerite-galena-quartz, and chalcopyrite-tennantite-tetrahedrite mineral associations are distinguished. The temperatures and composition of ore-forming solutions are shown.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"96 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87696317","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 : 2022-11-15DOI: 10.47765/0869-5997-2022-10017
A. Bolonin, V. Mamedov, I. Myznikov
In this article, we for the first time fully describe the geology and petrography of the iron quartzite formation, localized in Southeast Guinea in the Simandou mountain range. In this region, a meridional distribution belt of banded magnetite quartzites (itabirite) of the Lower Proterozoic Simandou metamorphic series has been mapped. The rocks form an extended (210 km) and narrow (0.4-7 km) complex synclinal structure in the background of the Archean granite-gneiss basement. The structure of the Simandou metamorphic series includes the lower sequence of metaterrigenous rocks up to 400-500 m thick (metasandstone, quartzite, phyllite, mica schist) and the upper itabiritic sequence up to 220-450 m thick. The metamorphism of the rocks of the series increases from north to south from the greenschist to epidoteamphibolite facies. Members of two varieties of banded iron rocks are distinguished in the itabiritic stratum - itabirite and amphibole itabirite. The composition of itabirite is (wt %): magnetite 51-55, quartz 48-36, and the rest is cummingtonite and mica. The composition of amphibole itabirite is (wt %): magnetite 39-47, quartz 31- 30, amphibole (cummingtonite) 24-15, the rest is hedenbergite, mica and calcite. Rich martite and hematitegoethite ores (60-66% Fe) are formed in the lateritic weathering crust after itabirite, forming manto deposits with a depth of 9 to 350 m.
{"title":"Iron quartzites of the Simandou mountain (Republic of Guinea)","authors":"A. Bolonin, V. Mamedov, I. Myznikov","doi":"10.47765/0869-5997-2022-10017","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10017","url":null,"abstract":"In this article, we for the first time fully describe the geology and petrography of the iron quartzite formation, localized in Southeast Guinea in the Simandou mountain range. In this region, a meridional distribution belt of banded magnetite quartzites (itabirite) of the Lower Proterozoic Simandou metamorphic series has been mapped. The rocks form an extended (210 km) and narrow (0.4-7 km) complex synclinal structure in the background of the Archean granite-gneiss basement. The structure of the Simandou metamorphic series includes the lower sequence of metaterrigenous rocks up to 400-500 m thick (metasandstone, quartzite, phyllite, mica schist) and the upper itabiritic sequence up to 220-450 m thick. The metamorphism of the rocks of the series increases from north to south from the greenschist to epidoteamphibolite facies. Members of two varieties of banded iron rocks are distinguished in the itabiritic stratum - itabirite and amphibole itabirite. The composition of itabirite is (wt %): magnetite 51-55, quartz 48-36, and the rest is cummingtonite and mica. The composition of amphibole itabirite is (wt %): magnetite 39-47, quartz 31- 30, amphibole (cummingtonite) 24-15, the rest is hedenbergite, mica and calcite. Rich martite and hematitegoethite ores (60-66% Fe) are formed in the lateritic weathering crust after itabirite, forming manto deposits with a depth of 9 to 350 m.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73091019","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 : 2022-11-15DOI: 10.47765/0869-5997-2022-10019
A. Baryshev
In this study we consider the features of the development of weakly lithified bottom sediments and the general structure of lake Natron against the background of its seasonal drying and watering. This study takes into account the laws of advection and the periodic placement of cellular zonal advective structures in space. The consedimentary structures in the lake sediments demonstrate the conditions for the formation of sodic ores and their positions. Provided space and aerial photographs depict unique genetic information about the evolution of geochemistry and the development of bottom morphology during sedimentation. This includes the presence of two sources that feed the lake - river and mud eruptions of the adjacent Oldoinyo-Lengai volcano, supposedly the only one on Earth that erupts carbonatite lavas. The combination of two sources and two processes leads to the development of an epimagmatic phreatic-hydrothermal recycling system. In it, the masses of the lake penetrate through fissure structures into the suprafocal space of the volcano, providing mud volcanism with solutions of soda masses containing organic matter of sediments. Volcanic soda eruptions are not carbonatite lavas. The morphological similarities and differences of structures are shown - small craters on the bottom of the lake, associated with the advection of thin layers of sedimentary material; large craters located nearby among volcanic strata along the shores of the lake; and both subsidence calderas and explosion calderas associated with magmatic and mud types of volcanism in the setting of strike-slip transtension.
{"title":"Advective structures of the bottom of lake Natron and its surroundings (Tanzania)","authors":"A. Baryshev","doi":"10.47765/0869-5997-2022-10019","DOIUrl":"https://doi.org/10.47765/0869-5997-2022-10019","url":null,"abstract":"In this study we consider the features of the development of weakly lithified bottom sediments and the general structure of lake Natron against the background of its seasonal drying and watering. This study takes into account the laws of advection and the periodic placement of cellular zonal advective structures in space. The consedimentary structures in the lake sediments demonstrate the conditions for the formation of sodic ores and their positions. Provided space and aerial photographs depict unique genetic information about the evolution of geochemistry and the development of bottom morphology during sedimentation. This includes the presence of two sources that feed the lake - river and mud eruptions of the adjacent Oldoinyo-Lengai volcano, supposedly the only one on Earth that erupts carbonatite lavas. The combination of two sources and two processes leads to the development of an epimagmatic phreatic-hydrothermal recycling system. In it, the masses of the lake penetrate through fissure structures into the suprafocal space of the volcano, providing mud volcanism with solutions of soda masses containing organic matter of sediments. Volcanic soda eruptions are not carbonatite lavas. The morphological similarities and differences of structures are shown - small craters on the bottom of the lake, associated with the advection of thin layers of sedimentary material; large craters located nearby among volcanic strata along the shores of the lake; and both subsidence calderas and explosion calderas associated with magmatic and mud types of volcanism in the setting of strike-slip transtension.","PeriodicalId":19636,"journal":{"name":"Ores and metals","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89314564","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 : 2022-08-06DOI: 10.47765/0869-5997-2022-10012
L. Vdovina
The structural position, petrographic composition, petroand geochemical features of amphibole-biotite, biotite and amblygonite-lepidolite granitoid of the study area are characterized. Taking into account these characteristics, it is proposed that the intrusive formations of the Tirekhtyakh and Endegechuy tectonic-magmatic series belong to the Tirekhtyakh whereas intrusive formations of Yano-Borulakh belong to the Arga-YnnakhKhai and Kester complexes. The distinctive features of the Tirekhtyakh complex are the diorite-granodioritegranite trend of differentiation and the amphibole-biotite association of mafic minerals. Biotite and two-mica granite of the Yano-Borulakh series are assigned to the Arga-Ynnakh-Khai complex by the absence of diorite components in the differentiation trend and amphibole among mafic minerals. Small bodies and dikes of amblygonite-lepidolite granite and leucogranite with reverse trends of differentiation, the presence of lithium micas, the presence of topaz and the minerals of the amblygonite-montebrasite series, as well as high contents of lithium, phosphorus and fluorine, are combined into the Kester complex. Studies are recommended to clarify the age of igneous complexes using modern methods and justify the identification of the Tirekhtyakh complex with the Tirekhtyakh massif as a petrotype.
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