Paleozoic Multi-Stage Magmatic Events Related to Proto-Tethys and Paleo-Tethys Evolution: Insights from Intrusive Rocks in the Eastern Altyn Orogen, NW China
Jiyong Li, Yanqing Xia, Xilong Zhang, Haoyuan Jiang, Tianzhu Lei, Yongchao Wang, Yanhong Liu, Shanpin Liu, Xiaobao Zhang
Paleozoic Multi-Stage Magmatic Events Related to Proto-Tethys and Paleo-Tethys Evolution: Insights from Intrusive Rocks in the Eastern Altyn Orogen, NW China
Abundant mafic-felsic intrusions distributed in the Altyn Orogen record orogenic histories related to Proto-Tethys and Paleo-Tethys evolution. Zircon U-Pb dating of the intrusive rocks in the eastern Altyn Orogen identifies at least three major tectono-magmatic episodes, yielding ages of ∼426, ∼376–373 and ∼269–254 Ma. The first two emplacement episodes correspond to the post-collisional magmatism in the Altyn Orogen. The ∼426 Ma granitoids possess adakitic characteristics coupled with enriched isotopes, suggesting that they originated from partial melting of thickened lower continental crust induced by upwelling asthenospheric mantle after slab break-off of the South Altyn Ocean Plate. Next, the ∼376–373 Ma mafic-intermediate rocks and coeval granitoids represent a large thermal event that involved mantle melting with induced new juvenile lower continental crust melting in a post-collisional extensional setting. Finally, the ∼254 Ma diabase dykes intruded into the ∼269 Ma granitoids, which were related to the widespread Late Paleozoic magmatism resulting from Paleo-Tethys Ocean subduction. Post-collisional magmatism in the Altyn Orogen significantly enhances understanding of the tectono-magmatic evolution in the northern Tibetan Plateau. The penetrative influence of Paleo-Tethys Ocean subduction was more extensive than previously thought.
Proto-Tethys / Paleo-Tethys / Altyn Orogen / multi-stage magmatic events / magnetic cores
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