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Petrogenesis and tectonic implications of the Triassic rhyolites in the East Kunlun Orogenic Belt, northern Tibetan Plateau

Shao, Fengli; Niu, Yaoling; Kong, Juanjuan; Liu, Yi; Wang, Guodong; Zhang, Yu

Petrogenesis and tectonic implications of the Triassic rhyolites in the East Kunlun Orogenic Belt, northern Tibetan Plateau Thumbnail


Authors

Fengli Shao

Yaoling Niu

Juanjuan Kong

Yi Liu

Guodong Wang

Yu Zhang



Abstract

The East Kunlun Orogenic Belt (EKOB), which is in the northern part of the Greater Tibetan Plateau, contains voluminous Late Triassic intermediate-felsic volcanic rocks. In the east end of the EKOB, we identified highly differentiated peralkaline-like Xiangride rhyolites (∼209 Ma) that differ from the widespread andesitic-rhyolitic Elashan volcanics (∼232–225 Ma) in terms of their field occurrences and mineral assemblages. The older, more common calc-alkaline felsic Elashan volcanics may have originated from partial melting of the underthrust Paleo-Tethys oceanic crust under amphibolite facies conditions associated with continental collision. The felsic Elashan volcanics and syn-collisional granitoids of the EKOB are different products of the same magmatic event related to continental collision. The Xiangride rhyolites are characterized by elevated abundances of high field strength elements, especially the very high Nb and Ta contents, the very low Ba, Sr, Eu, P, and Ti contents; and the variably high 87Sr/86Sr ratios (up to 0.96), exhibiting remarkable similarities to the characteristic peralkaline rhyolites. The primitive magmas parental to the Xiangride rhyolites were most likely alkali basaltic magmas that underwent protracted fractional crystallization with continental crust contamination. The rock associations from the early granitoids and calc-alkaline volcanic rocks to the late alkaline basaltic dikes and peralkaline-like rhyolites in the Triassic provide important information about the tectonic evolution of the EKOB from syn-collisional to post-collisional. We infer that the transition from collisional compression to post-collisional extension occurred at about 220 Ma.

Citation

Shao, F., Niu, Y., Kong, J., Liu, Y., Wang, G., & Zhang, Y. (2021). Petrogenesis and tectonic implications of the Triassic rhyolites in the East Kunlun Orogenic Belt, northern Tibetan Plateau. Geoscience Frontiers, 12(6), Article 101243. https://doi.org/10.1016/j.gsf.2021.101243

Journal Article Type Article
Acceptance Date May 27, 2021
Online Publication Date May 29, 2021
Publication Date 2021-11
Deposit Date Jun 1, 2021
Publicly Available Date Mar 29, 2024
Journal Geoscience Frontiers
Print ISSN 1674-9871
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 12
Issue 6
Article Number 101243
DOI https://doi.org/10.1016/j.gsf.2021.101243

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