Pub Date : 2024-03-10DOI: 10.1134/s0016852123070038
N. V. Borovkov, G. L. Leitchenkov, I. A. Kamenev
Abstract
Orthopyroxene granitoids (designated as charnockites or granitoids of the charnockite series) are characterized by varying silica and felsic mineral content, with the orthopyroxene (hypersthene) phase as the main characteristic mafic mineral component. These rocks are abyssal and represent parts of intrusions or form their own igneous complexes at the depth of the lower crust under CO2-undersaturated and dry conditions, which can be achieved within any tectonic setting. Therefore, petrogenetic models for orthopyroxene granitoids as well as for all types of granitoids from different locations are sufficiently applicable for a reconstruction of paleogeodynamic conditions in a certain region. The East Antarctic shield is characterized by Archean blocks embedded within orogens of Mesoproterozoic, Late Mesoproterozoic‒Early Neoproterosoic and Late Neoproterosoic‒Early Paleozoic age, and syn- and post-orogenic intrusions composed of orthopyroxene granitoids and related rocks are widely spread and form a prominent volume of the East Antarctic orogens. According to paleogeodynamic reconstructions of Rodinia, Pannotia and Gondwana supercontinents the East Antarctic shield represents a significant volume of supercontinents’ crust. Petrogenetic models for East Antarctic orthopyroxene granitoids became fundamental for any paleogeodynamic reconstractions of supercontinents. We collected structural geology, tectonics, and geochronology data for orthopyroxene granitoid intrusions belonging to orogens of certain age and combined with the plotting of geochemical data in major and rare element tectonic discrimination diagrams, also analyzed the Sm‒Nd isotope system data. The East Antarctic orthopyroxene granitoids tightly related to orogens are characterized by magmatic sources determined as combination of mafic lower crust, upper crust and juvenile mantle materials mixing up in different proportions depending on type of orogeny. It was established that orthopyroxene granitoids related to Mesoproterozoic and Late Mesoproterozoic‒Early Neoproterosoic orogens formed at different stages of long-lived collision transforming from ocean‒continent to continent‒continent types whereas Late Neoproterosoic‒Early Paleozoic orthopyroxene granitoids arose in post-collision tectonic setting.
{"title":"Constraints on Geodynamic Setting of East Antarctic Orthopyroxene Granitoids Intrusions","authors":"N. V. Borovkov, G. L. Leitchenkov, I. A. Kamenev","doi":"10.1134/s0016852123070038","DOIUrl":"https://doi.org/10.1134/s0016852123070038","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Orthopyroxene granitoids (designated as charnockites or granitoids of the charnockite series) are characterized by varying silica and felsic mineral content, with the orthopyroxene (hypersthene) phase as the main characteristic mafic mineral component. These rocks are abyssal and represent parts of intrusions or form their own igneous complexes at the depth of the lower crust under CO<sub>2</sub>-undersaturated and dry conditions, which can be achieved within any tectonic setting. Therefore, petrogenetic models for orthopyroxene granitoids as well as for all types of granitoids from different locations are sufficiently applicable for a reconstruction of paleogeodynamic conditions in a certain region. The East Antarctic shield is characterized by Archean blocks embedded within orogens of Mesoproterozoic, Late Mesoproterozoic‒Early Neoproterosoic and Late Neoproterosoic‒Early Paleozoic age, and syn- and post-orogenic intrusions composed of orthopyroxene granitoids and related rocks are widely spread and form a prominent volume of the East Antarctic orogens. According to paleogeodynamic reconstructions of Rodinia, Pannotia and Gondwana supercontinents the East Antarctic shield represents a significant volume of supercontinents’ crust. Petrogenetic models for East Antarctic orthopyroxene granitoids became fundamental for any paleogeodynamic reconstractions of supercontinents. We collected structural geology, tectonics, and geochronology data for orthopyroxene granitoid intrusions belonging to orogens of certain age and combined with the plotting of geochemical data in major and rare element tectonic discrimination diagrams, also analyzed the Sm‒Nd isotope system data. The East Antarctic orthopyroxene granitoids tightly related to orogens are characterized by magmatic sources determined as combination of mafic lower crust, upper crust and juvenile mantle materials mixing up in different proportions depending on type of orogeny. It was established that orthopyroxene granitoids related to Mesoproterozoic and Late Mesoproterozoic‒Early Neoproterosoic orogens formed at different stages of long-lived collision transforming from ocean‒continent to continent‒continent types whereas Late Neoproterosoic‒Early Paleozoic orthopyroxene granitoids arose in post-collision tectonic setting.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097800","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 : 2024-03-10DOI: 10.1134/s0016852123070129
B. V. Shumskiy, E. A. Gusev, G. L. Leitchenkov, O. E. Smirnov, G. A. Cherkashov, A. A. Chernykh
Abstract
The Gramberg All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (FSBI VNIIOkeangeologia) carries out a wide range of research in the fields of geology, engineering geology, geophysics, and geochemistry. The specialists of the institute perform studies using most-up-to-date equipment in several directions, including the study of the geology and mineral resources of the Arctic, Antarctic and the World Ocean. The geological and tectonic maps and atlases of the Eurasian sector of the Arctic shelf and adjacent deepwater zones of the Arctic Ocean have been compiled. This allow one to recognize the rift-related basins on the East Arctic shelf of Russia, and the conjunction areas of the Lomonosov, Gakkel, and Mendeleev oceanic ridges with the Eurasian continental margin. A comprehensive interpretation of geological and geophysical data has revealed features of the tectonics of the Amerasian Basin, which indicate that the evolution of the basin structures took place under conditions of continental rifting. One of the main scientific conclusions drawn at the preparation of the Submission of the Russian Federation in respect of the continental shelf boundary in the Arctic Ocean is the proof of the continental nature of the structures of the Central Arctic Rise Complex: the Lomonosov Ridge, Podvodnikov Basin, Alpha–Mendeleev Rise, Chukchi Basin, and Chukchi Borderland. This conclusion is confirmed by the characteristics of the main layers of the Earth’s crust in the above structures. A geodynamic model of the evolution of the Precambrian complexes of East Antarctica has been developed and the main tectonic provinces of Antarctica have been distinguished. A universal seismostratigraphic model of sedimentary basins has been developed for the marginal seas of East Antarctica. An important area of research in Antarctica was the study of the subglacial Lake Vostok. When studying the history of the formation of sulfide mineralization, it was found that the discharge of hydrothermal ore-bearing solutions most often occurs continuously, and only the intensity of the ore formation process changes with time. The possibility of formation of massive sulfide ore volumes additional to the main surface deposit due to metasomatic replacement of host igneous rocks has also been established.
{"title":"The Geology of the World Ocean (Arctic and Antarctic): Achievements and New Research","authors":"B. V. Shumskiy, E. A. Gusev, G. L. Leitchenkov, O. E. Smirnov, G. A. Cherkashov, A. A. Chernykh","doi":"10.1134/s0016852123070129","DOIUrl":"https://doi.org/10.1134/s0016852123070129","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Gramberg All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (FSBI VNIIOkeangeologia) carries out a wide range of research in the fields of geology, engineering geology, geophysics, and geochemistry. The specialists of the institute perform studies using most-up-to-date equipment in several directions, including the study of the geology and mineral resources of the Arctic, Antarctic and the World Ocean. The geological and tectonic maps and atlases of the Eurasian sector of the Arctic shelf and adjacent deepwater zones of the Arctic Ocean have been compiled. This allow one to recognize the rift-related basins on the East Arctic shelf of Russia, and the conjunction areas of the Lomonosov, Gakkel, and Mendeleev oceanic ridges with the Eurasian continental margin. A comprehensive interpretation of geological and geophysical data has revealed features of the tectonics of the Amerasian Basin, which indicate that the evolution of the basin structures took place under conditions of continental rifting. One of the main scientific conclusions drawn at the preparation of the Submission of the Russian Federation in respect of the continental shelf boundary in the Arctic Ocean is the proof of the continental nature of the structures of the Central Arctic Rise Complex: the Lomonosov Ridge, Podvodnikov Basin, Alpha–Mendeleev Rise, Chukchi Basin, and Chukchi Borderland. This conclusion is confirmed by the characteristics of the main layers of the Earth’s crust in the above structures. A geodynamic model of the evolution of the Precambrian complexes of East Antarctica has been developed and the main tectonic provinces of Antarctica have been distinguished. A universal seismostratigraphic model of sedimentary basins has been developed for the marginal seas of East Antarctica. An important area of research in Antarctica was the study of the subglacial Lake Vostok. When studying the history of the formation of sulfide mineralization, it was found that the discharge of hydrothermal ore-bearing solutions most often occurs continuously, and only the intensity of the ore formation process changes with time. The possibility of formation of massive sulfide ore volumes additional to the main surface deposit due to metasomatic replacement of host igneous rocks has also been established.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097165","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 : 2024-03-10DOI: 10.1134/s001685212307004x
G. A. Cherkashov, A. V. Firstova, A. S. Bich, K. A. Kuksa, A. A. Sukhanova, E. S. Yakovenko, T. V. Stepanova, V. Yu. Kuznetsov, A. E. Musatov, A. Yu. Petrov, F. E. Maksimov, B. E. Beltenev