Confirmation of ultrahigh-temperature metapelitic granulite in the Altay orogen and its geological significance

Tong, Lingling; Chen, Yibing; Chen, Linli

doi:10.1007/s11434-014-0319-1

Cited by 9 publications

(5 citation statements)

References 29 publications

(44 reference statements)

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“…The structural and isotopic data show that the Permian thermal event is marked by the development of a large‐scale extensional core complex associated with massive re‐melting of the Devonian lower crust. In the Chinese Altai Zone, the Permian high temperature event is well known and attributed to an extensional intra‐plate setting (L. H. Chen & Han, 2006; C. L. Zhang et al., 2012) related to a mantle plume activity (L. X. Tong et al., 2013; Y. Tong et al., 2014). However, recent studies by Broussolle et al.…”

Section: Discussionmentioning

confidence: 99%

“…The Permian magmatism is also associated with partial melting and high temperature to ultra‐high temperature metamorphism dated at ca . 300–260 Ma, and can be identified in particular in the southern part of the Chinese Altai Zone (Briggs et al., 2007; Broussolle et al., 2018; Kozakov et al., 2011; Kröner et al., 2010; L. X. Tong et al., 2013).…”

Section: Geological Settingmentioning

confidence: 99%

“…L. Zhang et al, 2012) related to a mantle plume activity (L. X. Tong et al, 2013;Y. Tong et al, 2014).…”

Section: Summary Of the Geodynamic Evolution Of The Mongolian Altai Z...mentioning

confidence: 99%

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Paleozoic Geodynamics and Architecture of the Southern Part of the Mongolian Altai Zone

et al. 2022

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The Mongolian Altai Zone of the Central Asian Orogenic Belt has been traditionally interpreted as a mosaic of Paleozoic magmatic arcs, back‐arcs, and Precambrian continental terranes. In order to define its architecture and its tectonic evolution, three domains previously interpreted as terranes were investigated. The findings show that the Northern and Central domains are formed by a metamorphic sequence characterized by Barrovian S1 fabric transposed by recumbent folds and dominant sub‐horizontal amphibolite facies S2 schistosity. The latter is associated with the intrusions of late Devonian syntectonic granite sheets and anatexis in the south. The Southern domain is formed by early Permian migmatites and anatectic granites separated from the metamorphic envelope by amphibolite to green‐schist facies D3 shear zone cross‐cutting S2 fabrics. All domains have been reworked by E‐W upright folds associated with axial‐planar greenschist facies cleavage, reflecting the final mid‐Permian to Triassic D4 shortening. Lithological, geochemical, and U‐Pb zircon analyses of metasediments of all domains indicate that they are formed by Ordovician mature quartzite derived from Precambrian basement intruded by Cambrian‐Ordovician continental arc and Silurian immature graywacke which originated through erosion of an oceanic arc. Altogether, the whole sequence represents a fore‐arc basin in front of a migrating arc affected by thickening and late Devonian extension. The Southern domain is interpreted as an early Permian core complex amplified by mid‐Permian to Triassic compression. The apparent “terrane” architecture of the Mongol Altai Zone originated due to Devonian and Permian heterogeneous reworking of a giant Ordovician to Silurian fore‐arc basin.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Paleozoic Geodynamics and Architecture of the Southern Part of the Mongolian Altai Zone

et al. 2022

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“…299 Ma for migmatite leucosomes (Broussolle et al, ) and 292 Ma (W. Wang et al, ) and ca. 280 Ma for metapelitic granulite (Tong et al, ). Migmatite and granulite in the core of the extrusion zone were later intruded by gabbros and granites, which were dated 284–280 Ma by U‐Pb zircon method (Broussolle et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

et al. 2019

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Kinematic significance and time scales of geodynamic processes forming the Altai OrogenicBelt are addressed through structural and petrological analysis combined with zircon and monazite geochronology. The study area is composed of orogenic lower crust represented by a Devonian migmatite-magmatite complex and orogenic middle and upper crust formed by an amphibolite-facies Ordovician sedimentary sequence and a weakly to unmetamorphosed Devonian volcano-sedimentary cover, respectively. The orogenic lower and middle crust were first affected by moderate thickening, which formed subhorizontal Barrovian metamorphic schistosity. This fabric was reworked by deep crustal melting and intrusion of granite sheets during horizontal extension at 400-380 Ma. Soon after, this horizontal fabric was affected by NW-SE shortening generating crustal-scale upright folding associated with subvertical flow of still partially molten orogenic lower crust. During this event, the orogenic lower and middle crust were tightly juxtaposed with upper crustal sedimentary rocks. The last event was related with a NE-SW oriented convergence resulting in large-scale folding and megafold interference pattern in the Permian at 280-273 Ma. Combined with existing regional data, our results allow proposing a Devonian tectonic switching from compression to extension and back to compression, as a response to variations of subduction dynamics between slab advance and retreat in a Pacific-type suprasubduction system. The Permian folding was associated with the progressive northward exhumation of thermally softened crust. This tectonic evolution is in response to the indentation of the rigid Junggar arc domain into the weak Altai wedge.

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“…However, there are one or two exceptions. For example, several types of granulites, including low-and high-pressure pelitic granulite, medium-to high-pressure mafic granulites, high-pressure felsic granulite, and (ultra) high-temperature pelitic granulite, have been exhumed in the Altay orogen (e.g., Chen et al, 2006;Li et al, 2014;Tong et al, 2014aTong et al, , 2014bWang et al, 2009;Wei et al, 2007), part of the accretionary Central Asian orogenic belt. Highpressure granulites in these Phanerozoic orogens are fundamentally products of oceanic subduction, and not continental collision, because their country rocks are mostly ophiolite suite rocks or ophiolitic mélange (Shen et al, 2014, and references therein).…”

Section: Metamorphic P-t Paths and Tectonic Implicationmentioning

confidence: 99%

Metamorphic evolution and SIMS U-Pb geochronology of the Qingshigou area, Dunhuang block, NW China: Tectonic implications of the southernmost Central Asian orogenic belt

Wang

Chen

et al. 2016

Lithosphere

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Garnet-bearing mafic granulite and amphibolite exposed as lenses, boudins, or interlayers within metasediments in the Qingshigou area, Dunhuang block, southernmost Central Asian orogenic belt, record important information for understanding the tectono-metamorphic evolution of subduction and collision zones in the southern Central Asian orogenic belt during the mid-Paleozoic. Three stages of metamorphic assemblages (M1, M2, M3) are recognized in the high-and medium-pressure mafic granulite and amphibolite. In the high-pressure mafic granulite, the prograde assemblage (M1) is represented by inclusion minerals (hornblende + plagioclase + quartz) preserved in garnet porphyroblasts; the metamorphic peak assemblage (M2) is characterized by garnet porphyroblasts and matrix minerals (garnet + clinopyroxene + plagioclase + quartz ± zircon ± titanite); and the retrograde assemblage (M3) is marked by coronitic symplectite (hornblende + plagioclase + quartz ± magnetite) rimming the garnet porphyroblasts. In the medium-pressure mafic granulite, the prograde assemblage (M1) of hornblende + plagioclase + quartz is included in the garnet porphyroblasts; the peak assemblage (M2) consists of garnet + orthopyroxene + clinopyroxene + plagioclase + quartz ± zircon ± titanite (M2) in the matrix; and the retrograde assemblage (M3) of hornblende + orthopyroxene + plagioclase + quartz (M3) surrounds the garnet porphyroblasts. In the amphibolite, the prograde assemblage (hornblende + plagioclase + quartz + ilmenite) is preserved as inclusions in garnet (M1); the peak assemblage (M2) is composed of garnet + hornblende + plagioclase + quartz ± zircon ± titanite; and the retrograde assemblage (M3), consisting of hornblende + biotite + plagioclase + quartz + epidote + magnetite, rings the garnet porphyroblasts. Geothermobarometric calculations suggest that the metamorphic pressure-temperature paths pass from 568 °C and 8.8 kbar through 607 °C and 10.6 kbar and 861 °C and 16.9 kbar and finally to 598 °C and 4.4 kbar for the high-pressure mafic granulite; from 756 °C and 9.0 kbar through 750-874 °C and 9.3-11.6 kbar to 675 °C and 4.7 kbar for the medium-pressure mafic granulite; and from 686 °C and 7.6 kbar through 715-766 °C and 10.6-11.2 kbar to 671 °C and 5.6 kbar for the amphibolite, and the paths show clockwise pressuretemperature loops typical of an orogenic process. The metamorphic peak of the high-pressure mafic granulite lies in the eclogite facies, which is indicative of a subduction zone environment. High-resolution secondary ion mass spectrometry (SIMS) U-Pb dating of metamorphic zircon indicates that the metamorphism occurred in the Early Silurian (ca. 430 Ma) and lasted for at least 65 m.y. This study reveals a possible southward subduction history of a branch of the Paleo-Asian Ocean, the Liuyuan Ocean, from the Silurian to Late Devonian, which may be an important event in the accretionary history of the Central Asian orogenic belt.

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Confirmation of ultrahigh-temperature metapelitic granulite in the Altay orogen and its geological significance

Cited by 9 publications

References 29 publications

Paleozoic Geodynamics and Architecture of the Southern Part of the Mongolian Altai Zone

Paleozoic Geodynamics and Architecture of the Southern Part of the Mongolian Altai Zone

Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

Metamorphic evolution and SIMS U-Pb geochronology of the Qingshigou area, Dunhuang block, NW China: Tectonic implications of the southernmost Central Asian orogenic belt

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