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Late Devonian-Early Carboniferous magmatism in the Lhasa terrane and its tectonic implications: Evidences from detrital zircons in the Nyingchi Complex

Guo, Liang; Zhang, Hong-Fei; Harris, Nigel; Xu, Wang-Chun and Pan, Fa-Bin (2016). Late Devonian-Early Carboniferous magmatism in the Lhasa terrane and its tectonic implications: Evidences from detrital zircons in the Nyingchi Complex. Lithos, 245 pp. 47–59.

DOI (Digital Object Identifier) Link: https://doi.org/10.1016/j.lithos.2015.06.018
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Abstract

The Late Paleozoic tectonic evolution of the Lhasa terrane remains poorly understood due to the paucity of the Late Paleozoic magmatic rocks exposed at the surface. Detrital zircons in the sedimentary rocks can provide a record of magmatic rocks that have been eroded. Here we report detrital zircon U-Pb ages, trace-element and Hf isotopic data of metasedimentary rocks from the Nyingchi Complex in the eastern Himalayan syntaxis. Detrital zircons from the metasedimentary rocks yield major age populations of 330–364 Ma, 490–800 Ma, 1000–1200 Ma, and 1500–1800 Ma. The weighted mean ages of the youngest three detrital zircons indicate Carboniferous (~ 330 Ma) depositional age for their sedimentary protoliths. Provenance analysis indicates that the sedimentary detritus was sourced from the Lhasa terrane itself. The presence of abundant 330–364 Ma detrital zircons indicates that the Lhasa terrane was characterized by Late Devonian-Early Carboniferous magmatism. The trace-element compositions of the 330–364 Ma detrital zircons indicate that their magmatic host rocks mainly include mafic rocks and granitoids, and minor carbonatite. Some mafic host rocks probably formed in rift-related tectonic setting, and the others formed in arc-related tectonic settings. The granitic host rocks were S-type granites. The 330–391 Ma zircons have negative εHf(t) values (− 19.3 to − 2.5), suggesting that their magmatic host rocks resulted from partial melting of the enriched mantle or ancient crustal materials. Combined with previous studies, we propose that the Late Devonian-Early Carboniferous magmatic rocks in the Lhasa terrane probably formed in an arc-back-arc system which resulted from the southward subduction of the Paleo-Tethys oceanic crust. The back-arc basin developed as the Sumdo Paleo-Tethys ocean, which began to shrink as oceanic crust subducted northwards underneath the North Lhasa terrane during the Late Carboniferous-Permian and finally closed during the Triassic.

Item Type: Journal Item
Copyright Holders: 2015 Elsevier B.V.
ISSN: 0024-4937
Project Funding Details:
Funded Project NameProject IDFunding Body
Not Set41073046Natural Science Foundation of China
Not Set41303023Natural Science Foundation of China
Not Set2101105SinoProb 04-02
Keywords: Lhasa terrane; Detrital zircon; Zircon trace-element; Back-arc basin; Tectonic evolution
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 45376
Depositing User: Nigel Harris
Date Deposited: 24 Feb 2016 13:27
Last Modified: 05 May 2019 10:33
URI: http://oro.open.ac.uk/id/eprint/45376
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