Nd-Hf Isotopic Decoupling of the Silurian—Devonian Granitoids in the Chinese Altai: A Consequence of Crustal Recycling of the Ordovician Accretionary Wedge?

Huang, Yanqiong; Jiang, Yingde; Yang, Yu; Collett, Stephen; Wang, Sheng; Shu, Tan; Xu, Kang

doi:10.1007/s12583-019-1217-x

Cited by 11 publications

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“…These two groups of rocks are well developed in other parts of the Mongolian and Chinese Altai zones as well (Figures 7, 15b, and 15c). The studied Devonian granitoids correspond to S‐ and I‐type felsic igneous rocks typical of active continental margins (Burenjargal et al., 2016; Cai et al., 2015; Huang et al., 2020; Jiang et al., 2016) and the Permian ones show spatial and compositional continuity with ca . 270–280 Ma A‐ and S‐type granitoids concentrated along the southern margin of the Chinese Altai Zone (Y. Tong et al., 2014).…”

Section: Discussionmentioning

confidence: 99%

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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