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Federico Mantovani - One of the best experts on this subject based on the ideXlab platform.
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contact metamorphism in middle ordovician arc rocks sw sardinia italy new paleogeographic constraints
Lithos, 2016Co-Authors: Luca Giacomo Costamagna, Franco Marco Elter, Laura Gaggero, Federico MantovaniAbstract:Abstract In the early Cambrian Bithia Formation in the Variscan foreland of Sardinia, a Middle Ordovician granitic intrusion (478–457 Ma) is hosted by marly metasedimentary rocks that were affected by high-temperature (HT) metamorphism. A detailed structural–petrographical transect was conducted through the granitic intrusion and its host rocks. Field data and relationships between HT/low-pressure (LP) mineral assemblages in the metasedimentary rocks (Grt + Wo + Ves in carbonate lenses and And in pelite) demonstrate that the study area was affected by a polyphase HT overprint (I: T = 520–620 °C at XCO2 = 0.1, P: 0.2–0.4 GPa; and II: T = 600–670 °C at XCO2 = 0.1, P = 0.2–0.4 GPa) that pre-dates the Variscan tectonic, metamorphic, and igneous phases. In the Canigo or Canigou Massif (Eastern Pyrenees), the Somail Massif (Montagne Noire), and the Ruitor Massif (Internal Massifs, NW Alps), Middle Ordovician orthogneiss with relict igneous textures are deciphered despite being overprinted by Variscan amphibolite-to-granulite-facies metamorphism and subsequent Alpine low-grade metamorphism. Comparisons of associated igneous and metasedimentary rocks in the Sardinia foreland with the High-Grade Metamorphic Complex in the Variscan Axial Zone and the Canigou Massif indicate a convergent Middle Ordovician evolution that was overprinted by HT Variscan metamorphism.
Fırat Şengün - One of the best experts on this subject based on the ideXlab platform.
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p t t evolution of eclogite blueschist facies metamorphism in alanya Massif time and space relations with hp event in bitlis Massif turkey
International Journal of Earth Sciences, 2016Co-Authors: Mete Çetİnkaplan, Aral I. Okay, Amaury Pourteau, Osman Candan, Roland Oberhänsli, Fukun Chen, Huseyin Kozlu, Ersin O Koralay, Fırat ŞengünAbstract:The Alanya Massif, which is located to the south of central Taurides in Turkey, presents a typical nappe pile consisting of thrust sheets with contrasting metamorphic histories. In two thrust sheets, Sugozu and Gundogmus nappes, HP metamorphism under eclogite (550–567 °C/14–18 kbar) and blueschist facies (435–480 °C/11–13 kbar) conditions have been recognized, respectively. Whereas the rest of the Massif underwent MP metamorphism under greenschist to amphibolite facies (525–555 °C/6.5–7.5 kbar) conditions. Eclogite facies metamorphism in Sugozu nappe, which consists of homogeneous garnet–glaucophane–phengite schists with eclogite lenses is dated at 84.8 ± 0.8, 84.7 ± 1.5 and 82 ± 3 Ma (Santonian–Campanian) by 40Ar/39Ar phengite, U/Pb zircon and rutile dating methods, respectively. Similarly, phengites in Gundogmus nappe representing an accretionary complex yield 82–80 Ma (Campanian) ages for blueschist facies metamorphism. During the exhumation, the retrograde overprint of the HP units under greenschist–amphibolite facies conditions and tectonic juxtaposition with the Barrovian units occurred during Campanian (75–78 Ma). Petrological and geochronological data clearly indicate a similar Late Cretaceous tectonometamorphic evolution for both Alanya (84–75 Ma) and Bitlis (84–72 Ma) Massifs. They form part of a single continental sliver (Alanya–Bitlis microcontinent), which was rifted from the southern part of the Anatolide–Tauride platform. The P–T–t coherence between two Massifs suggests that both Massifs have been derived from the closure of the same ocean (Alanya–Bitlis Ocean) located to the south of the Anatolide–Tauride block by a northward subduction. The boundary separating the autochthonous Tauride platform to the north from both the Alanya and Bitlis Massifs to the south represents a suture zone, the Pamphylian–Alanya–Bitlis suture.
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P–T–t evolution of eclogite/blueschist facies metamorphism in Alanya Massif: time and space relations with HP event in Bitlis Massif, Turkey
International Journal of Earth Sciences, 2014Co-Authors: Mete Çetİnkaplan, Aral I. Okay, Amaury Pourteau, Osman Candan, O. Ersin Koralay, Roland Oberhänsli, Fukun Chen, Huseyin Kozlu, Fırat ŞengünAbstract:The Alanya Massif, which is located to the south of central Taurides in Turkey, presents a typical nappe pile consisting of thrust sheets with contrasting metamorphic histories. In two thrust sheets, Sugozu and Gundogmus nappes, HP metamorphism under eclogite (550–567 °C/14–18 kbar) and blueschist facies (435–480 °C/11–13 kbar) conditions have been recognized, respectively. Whereas the rest of the Massif underwent MP metamorphism under greenschist to amphibolite facies (525–555 °C/6.5–7.5 kbar) conditions. Eclogite facies metamorphism in Sugozu nappe, which consists of homogeneous garnet–glaucophane–phengite schists with eclogite lenses is dated at 84.8 ± 0.8, 84.7 ± 1.5 and 82 ± 3 Ma (Santonian–Campanian) by 40Ar/39Ar phengite, U/Pb zircon and rutile dating methods, respectively. Similarly, phengites in Gundogmus nappe representing an accretionary complex yield 82–80 Ma (Campanian) ages for blueschist facies metamorphism. During the exhumation, the retrograde overprint of the HP units under greenschist–amphibolite facies conditions and tectonic juxtaposition with the Barrovian units occurred during Campanian (75–78 Ma). Petrological and geochronological data clearly indicate a similar Late Cretaceous tectonometamorphic evolution for both Alanya (84–75 Ma) and Bitlis (84–72 Ma) Massifs. They form part of a single continental sliver (Alanya–Bitlis microcontinent), which was rifted from the southern part of the Anatolide–Tauride platform. The P–T–t coherence between two Massifs suggests that both Massifs have been derived from the closure of the same ocean (Alanya–Bitlis Ocean) located to the south of the Anatolide–Tauride block by a northward subduction. The boundary separating the autochthonous Tauride platform to the north from both the Alanya and Bitlis Massifs to the south represents a suture zone, the Pamphylian–Alanya–Bitlis suture.
V. P. Kovach - One of the best experts on this subject based on the ideXlab platform.
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first evidence of ediacaran magmatism in the geological history of the mamyn terrane of the central asian fold belt
Russian Journal of Pacific Geology, 2015Co-Authors: A A Sorokin, N. M. Kudryashov, A B Kotov, V. P. KovachAbstract:U–Pb geochronological studies reveal that the gabbro of the Mikitkin Massif and quartz diorite of the Ust’-Garin Massif of the Mamyn Terrane, which were provisionally assigned to the Early Proterozoic Garin Complex, have ages of 583 ± 6 Ma and 607 ± 8 Ma, i.e. Upper Riphean–Lower Vendian. The geochemical features of the magmatic rocks of the studied Massifs indicate their suprasubduction origin. The parental melts of the magmatic rocks of the Garin Complex were formed in an active continental margin or ensialic island-arc setting due to melting of the subduction-modified depleted mantle source and the occurrence of contamination and fractional crystallization. These Massifs were developed during the Ediacaran Stage of the geological evolution of the Mamyn Terrane and presumably reflect Neoproterozoic convergent geodynamic processes. These processes likely caused the ultimate formation of the Precambrian continental Massifs in the eastern Central Asian fold belt, which were subsequently amalgamated into the structure of the epi-Paleozoic Amur microcontinent.
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Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position
Stratigraphy and Geological Correlation, 2007Co-Authors: A A Sorokin, N. M. Kudryashov, E. B. Sal’nikova, A B Kotov, V. P. KovachAbstract:Magmatic rocks of the Pikan and Un’ya Massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan Massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya Massif. As is suggested, the Pikan and Un’ya Massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development.
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Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position
Stratigraphy and Geological Correlation, 2007Co-Authors: A A Sorokin, N. M. Kudryashov, E. B. Sal’nikova, A B Kotov, V. P. KovachAbstract:Magmatic rocks of the Pikan and Un’ya Massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan Massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya Massif. As is suggested, the Pikan and Un’ya Massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development.
A A Sorokin - One of the best experts on this subject based on the ideXlab platform.
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the cambrian ordovician diorite granodiorite granite association of the mamyn terrane central asian fold belt u pb geochronological and geochemical data
Doklady Earth Sciences, 2017Co-Authors: A A Sorokin, N. M. KudryashovAbstract:New results of U–Pb geochronological and geochemical studies of rocks that form two structurally different Massifs in the Mamyn Terrane are presented here. It has been found that the age of amphibole–biotite granites in the Kosmataya Massif, Oktyabrskii Complex is 488 ± 5 Ma. The same age has been defined for gneissose diorite 488 ± 8 and granodiorite 488 ± 5 Ma of the Ust–Inkan Massif. The results indicate that all the studied rocks have an identical Late Cambrian–Early Ordovician age of about 488 Ma. Considering that they were formed within a single tectonic structure (Mamyn Terrane), spatially close to each other and have similar geochemical characteristics, they may be considered as a single diorite–granodiorite–granite association. The results obtained indicate that a stage of intensive felsic magmatism occurred in the Mamyn Terrane in the eastern part of the Central Asian Fold Belt. This stage of magmatic activity is also clearly expressed in other continental Massifs in the eastern part of this belt, which may indicate their common geodynamic history.
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first evidence of ediacaran magmatism in the geological history of the mamyn terrane of the central asian fold belt
Russian Journal of Pacific Geology, 2015Co-Authors: A A Sorokin, N. M. Kudryashov, A B Kotov, V. P. KovachAbstract:U–Pb geochronological studies reveal that the gabbro of the Mikitkin Massif and quartz diorite of the Ust’-Garin Massif of the Mamyn Terrane, which were provisionally assigned to the Early Proterozoic Garin Complex, have ages of 583 ± 6 Ma and 607 ± 8 Ma, i.e. Upper Riphean–Lower Vendian. The geochemical features of the magmatic rocks of the studied Massifs indicate their suprasubduction origin. The parental melts of the magmatic rocks of the Garin Complex were formed in an active continental margin or ensialic island-arc setting due to melting of the subduction-modified depleted mantle source and the occurrence of contamination and fractional crystallization. These Massifs were developed during the Ediacaran Stage of the geological evolution of the Mamyn Terrane and presumably reflect Neoproterozoic convergent geodynamic processes. These processes likely caused the ultimate formation of the Precambrian continental Massifs in the eastern Central Asian fold belt, which were subsequently amalgamated into the structure of the epi-Paleozoic Amur microcontinent.
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Early paleozoic granitoids in the Lesser Khingan terrane, Central Asian Foldbelt: Age, geochemistry, and geodynamic interpretations
Petrology, 2011Co-Authors: A A Sorokin, N. M. Kudryashov, A B Kotov, E. B. Sal’nikova, S. D. Velikoslavinskii, S. Z. Yakovleva, A. M. Fedoseenko, Yu. V. PlotkinaAbstract:The U-Pb zircon dates obtained for the Sutara (480 ± 4 Ma), Kabalinskii (471 ± 10 Ma), and Durilovskii (461 ± 5 Ma) Massifs reliably confirm an Early Proterozoic orogenic event, which took place after granulite metamorphism at approximately 500 Ma (Wilde et al., 2003) in the Lesser Khingan (Jiamusi) terrane. The rocks emplaced most shortly after the main metamorphic event are the granites of the Sutara Massif and leucogranites of the Kabalinskii Massif, whose geochemistry is close to that of collision granites. The quartz diorites and subalkaline granites of the Durilovskii Massif, whose geochemistry suggests their origin in a postcollision environment with the participation of an enriched mantle source, were emplaced longer after metamorphic event and after the aforementioned Massifs.
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Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position
Stratigraphy and Geological Correlation, 2007Co-Authors: A A Sorokin, N. M. Kudryashov, E. B. Sal’nikova, A B Kotov, V. P. KovachAbstract:Magmatic rocks of the Pikan and Un’ya Massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan Massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya Massif. As is suggested, the Pikan and Un’ya Massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development.
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Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position
Stratigraphy and Geological Correlation, 2007Co-Authors: A A Sorokin, N. M. Kudryashov, E. B. Sal’nikova, A B Kotov, V. P. KovachAbstract:Magmatic rocks of the Pikan and Un’ya Massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan Massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya Massif. As is suggested, the Pikan and Un’ya Massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development.
Patrick Ledru - One of the best experts on this subject based on the ideXlab platform.
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Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps
Bulletin de la Société Géologique de France, 2009Co-Authors: Stéphane Guillot, Patrick Ledru, S. Di Paola, René-pierre Ménot, M.i Spalla, G. Gosso, Stéphane SchwartzAbstract:This paper reviews the geodynamic evolution of the Belledonne, Grandes Rousses and Oisans Massifs in the western Alps from Early Ordovician to Permian times. Three domains are distinguished. The eastern domain, which includes the NE Belledonne Massif and the inner Oisans Massif, records the subduction of the Central-European ocean along a NW dipping subduction zone. The western domain is marked by Cambro-Ordovician back-arc rifting (Chamrousse ophiolite) initiating the opening of the Rheic ocean. It was followed by Mid-Devonian obduction of the back-arc Chamrousse ophiolite, towards the NW in relation with the SE dipping subduction of the Saxo-Thuringian ocean. The central domain, including the SW part of the Belledonne Massif, the Grandes Rousses Massif and the outer Oisans Massif, records the Devonian to Carboniferous orogenic activity that produced calc-alkaline magmatism, Mg-K granite intrusions and syn-collisional sedimentation related to Visean nappe stacking that we relate to the closure of the Saxo-Thuringian ocean. Based on tectonostratigraphic correlations we propose that these domains initially correspond to the northeastward extension of the Bohemian Massif. During the late Carboniferous, the External Crystalline Massifs including Sardinia and Corsica were stretched towards the SW along the > 600 km long dextral External Crystalline Massifs shear zone. Offset of the Saxo-Thuringian and eo-Variscan suture zones from the Bohemian Massif to the ECM suggests a possible dextral displacement of about 300 km along the ECM shear zone.
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Modélisation géométrique 3D des granites stéphaniens du Massif du Pelvoux (Alpes, France)
Comptes Rendus Geoscience, 2005Co-Authors: Pierre Strzerzynski, Stéphane Guillot, Gabriel Courrioux, Patrick LedruAbstract:La modelisation 3D de la geometrie des granites Stephaniens du Massif du Pelvoux a permis de mettre en evidence le contexte cisaillant associe a leur mise en place. Dans les Massifs Cristallins Externes Francais, ces cisaillements se repartissent selon deux directions, N50 et N135, respectivement dextre et senestre. Ce systeme decrochant Carbonifere s'integre dans un contexte d'extension N-S connu dans l'ensemble de la chaine Varisque.
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Modélisation géométrique 3D des granites stéphaniens du Massif du Pelvoux (Alpes, France).
Comptes Rendus Géoscience, 2005Co-Authors: Pierre Strzerzynski, Stéphane Guillot, Gabriel Courrioux, Patrick LedruAbstract:La modélisation 3D de la géométrie des granites Stéphaniens du Massif du Pelvoux a permis de mettre en évidence le contexte cisaillant associé à leur mise en place. Dans les Massifs Cristallins Externes Français, ces cisaillements se répartissent selon deux directions, N50 et N135, respectivement dextre et sénestre. Ce système décrochant Carbonifère s'intègre dans un contexte d'extension N-S connu dans l'ensemble de la chaîne Varisque.
