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Two episodes of Eocene mafic magmatism in the southern Lhasa terrane imply an eastward propagation of slab breakoff

Wang, Zhenzhen and Zhao, Zhidan and Asimow, Paul D. and Li, Xuping and Meng, Yuanku and Liu, Dong and Mo, Xuanxue and Zhu, Di-Cheng and Tang, Yan and Cong, Fuyun (2022) Two episodes of Eocene mafic magmatism in the southern Lhasa terrane imply an eastward propagation of slab breakoff. Gondwana Research, 110 . pp. 31-43. ISSN 1342-937X. doi:10.1016/j.gr.2022.05.019. https://resolver.caltech.edu/CaltechAUTHORS:20220705-682866000

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Abstract

Past geodynamic events can be reconstructed using the spatial and temporal patterns of geochemical variability in igneous rocks. Here we apply this principle to define the timing and geometry of breakoff of the Neo-Tethyan slab after the India-Asia collision. Two episodes of mafic magmatism (∼53 Ma and ∼ 48 Ma) are preserved in the Quxu area of the southern Lhasa terrane (SL). We present their whole-rock geochemistry, zircon U-Pb ages, and in situ zircon Hf isotope ratios. The early gabbro (∼53 Ma) exhibits typical arc basalt characteristics, including enrichment of large-ion lithophile elements (LILEs), depletion of high-field strength elements (HFSEs), and radiogenic Nd and zircon Hf isotopes, implying that they were formed by partial melting of metasomatized lithospheric mantle. In comparison to the early gabbro, the late hornblende gabbro (∼48 Ma) contains higher contents of HFSEs (e.g., Nb, Zr) and relatively less radiogenic Nd and zircon Hf isotopes, suggesting interaction between the enriched sub-continental lithospheric mantle and asthenospheric mantle. It is likely that upwelling asthenosphere reached the central SL around 50 Ma and that the Neo-Tethyan slab tore off under this area at this time. The spatial and temporal distribution of mafic rocks across the whole southern Lhasa terrane show that this geochemical transition and hence, presumably, the tearing off of the Neo-Tethyan slab, propagated eastward along the collision zone throughout Paleocene-Eocene time.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.gr.2022.05.019DOIArticle
ORCID:
AuthorORCID
Asimow, Paul D.0000-0001-6025-8925
Cong, Fuyun0000-0002-3618-3924
Additional Information:© 2022 International Association for Gondwana Research. Published by Elsevier. Received 20 March 2022, Revised 14 May 2022, Accepted 14 May 2022, Available online 11 June 2022, Version of Record 17 June 2022. We thank the editor for handling this manuscript and two reviewers for constructive comments. We are grateful to Youqing Wei, Shan Liu for assistance of fieldwork in Tibet and geochemical analyses. This work is supported by the National Natural Science Foundation of China (Nos. 42121002, 42073035), Second Tibetan Plateau Scientific Expedition and Research (STEP) program (Grant No. 2019QZKK0702), and National Key Research and Development Project of China (Grant No. 2016YFC0600304), 111 Program (Grant No. B18048). CRediT authorship contribution statement. Zhenzhen Wang: Writing – original draft, Conceptualization, Methodology. Zhidan Zhao: Writing – review & editing, Supervision. Paul D. Asimow: Writing – review & editing, Supervision. Xuping Li: Supervision. Yuanku Meng: Supervision. Dong Liu: Supervision. Xuanxue Mo: Resources. Di-Cheng Zhu: Methodology. Yan Tang: Data curation. Fuyun Cong: Supervision. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China42121002
National Natural Science Foundation of China42073035
Second Tibetan Plateau Scientific Expedition and Research (STEP)2019QZKK0702
National Key Research and Development Project of China2016YFC0600304
Ministry of Science and Technology (China)B18048
Subject Keywords:Mafic rocks; Lithospheric mantle; Asthenosphere; Slab breakoff; Lhasa terrane
DOI:10.1016/j.gr.2022.05.019
Record Number:CaltechAUTHORS:20220705-682866000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220705-682866000
Official Citation:Zhenzhen Wang, Zhidan Zhao, Paul D. Asimow, Xuping Li, Yuanku Meng, Dong Liu, Xuanxue Mo, Di-Cheng Zhu, Yan Tang, Fuyun Cong, Two episodes of Eocene mafic magmatism in the southern Lhasa terrane imply an eastward propagation of slab breakoff, Gondwana Research, Volume 110, 2022, Pages 31-43, ISSN 1342-937X, https://doi.org/10.1016/j.gr.2022.05.019.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115319
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:08 Jul 2022 18:15
Last Modified:08 Jul 2022 18:15

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