Age and petrogenesis of A-type granites in the middle segment of the Bangonghu–Nujiang suture, Tibetan plateau

Qu, Xiaoming; Wang, Rui‐Jiang; Hongbo, Xin; Jiang, Junhua; Chen, Hua

doi:10.1016/j.lithos.2012.05.006

Cited by 96 publications

(38 citation statements)

References 34 publications

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“…(b) A 2 ‐type granites (ca. 112 Ma) in the northern Lhasa subterrane suggest a postcollision extensional setting (Qu et al, ). (c) Adakitic rocks and simultaneous bimodal volcanic rocks in Yanhu area (ca.…”

Section: Discussionmentioning

confidence: 99%

The geochronologic and geochemical constraints on the Early Cretaceous subduction magmatism in the central Lhasa subterrane, Tibet

et al. 2017

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A large volume of Early Cretaceous volcanic rocks are exposed in the central Lhasa subterrane, which are essential for models developed for understanding the evolution of Lhasa Terrane. However, the petrogenesis and geodynamic background of these rocks are still in debate. In this paper, we carried out a detailed study on the volcanic rocks of the Zenong Group, including andesite, dacite, and rhyolite from the Coqen area in the central Lhasa subterrane. Zircons from one dacitic tuff yields an age of 115.3 ± 1.1 Ma. All the rocks are enriched in light rare earth elements (LREEs), Th, U, and Pb and depleted in high field strength elements (HFSEs, e.g. Nb, Ta, P, and Ti). The dacite and rhyolite samples are high‐K calc‐alkaline to shoshonitic and are metaluminous to peraluminous. These felsic samples are characterized by negative ƐNd(t) (−8.9 to −2.1) and ƐHf(t) (−8.1 to −5.6) and have high radiogenic Pb isotopic composition (206Pb/204Pb = 18.6287–19.5578, 207Pb/204Pb = 15.7161–15.7720, and 208Pb/204Pb = 39.1440–40.6253). Particularly, a negative correlation between the ƐNd(t) values and SiO2 contents can be observed in these dacites and rhyolites. Meanwhile, the andesites exhibit similar Sr–Nd–Pb isotopic compositions to dacites and rhyolites (ƐNd(t) = −4.3; 206Pb/204Pb = 18.7119–18.8575, 207Pb/204Pb = 15.7159–15.7203, and 208Pb/204Pb = 39.2944–39.6036). Our new data indicate that different geochemical reservoirs are involved in generating the ca. 115 Ma magmatism in the central Lhasa subterrane. It is likely that dacites and rhyolites are derived from the magma mixing between the ancient basement‐derived melts and mantle‐derived melts with varying degrees of partial melting. The andesites might originate from partial melting of an ancient lithospheric mantle that have been metasomatized by fluids and/or melts derived from the Tethyan oceanic slab. Our results, together with recent studies, suggest that the Zenong Group volcanic rocks in the Coqen area may represent the magmatic responses to the break‐off of the southward subduction of the Bangong–Nujiang Tethyan oceanic slab.

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Section: Discussionmentioning

confidence: 99%

The geochronologic and geochemical constraints on the Early Cretaceous subduction magmatism in the central Lhasa subterrane, Tibet

et al. 2017

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“…Lhasa Qu et al, 2012;Zhu et al, 2009a), and eastern Gangdese (Zhu et al, 2009b); Early Cretaceous granitoids from eastern Lhasa (Pan et al, 2014) …”

Section: Whole-rock Sr-nd-pb-hf Isotopic Compositionsmentioning

confidence: 99%

Tectono-magmatic evolution of the Gaoligong belt, southeastern margin of the Tibetan plateau: Constraints from granitic gneisses and granitoid intrusions

et al. 2016

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“…However, Zeng et al (2018) had a different opinion about SNMZ; he considered it was an embryonic oceanic basin within the Lhasa Terrane. This basin likely has been closed during the Early Cretaceous as suggested by (a) the similar palaeo-latitudes between NL and CL (Bian et al, 2017) and (b) the presence of 116-to 110-Ma rock associations (high-K arc-like basalts and A2-type felsic rocks; Qu, Wang, Xin, Jiang, & Chen, 2012). 3 | ANALYTICAL METHODS…”

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Early Cretaceous arc granitoids from the central Lhasa subterrane: Production of the northward subduction of Yarlung Zangbo Neo‐Tethyan Ocean?

et al. 2018

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There is ongoing debate as to the genesis of the Lhasa Terrane during the Mesozoic (northward subduction of Yanglu‐Zangbo Tethyan Ocean [YZTO] or southward subduction of Bangong–Nujiang Tethyan Ocean [BNTO]). In this paper, we report a dataset of geochronology, geochemistry, and Sr–Nd–Hf isotopes for the Azhale granitoids in order to elucidate the dominant geodynamic processes of the central subterrane. These rocks are dated at 142.2 ± 1.0 and 136.6 ± 0.6 Ma by zircon LA–ICP–MS method, indicating that these rocks were contemporaneous. In situ zircon Hf isotopic analyses yielded εHf(t) values of −4.2 to −0.1. Geochemically, these samples mostly belong to calc‐alkaline series and show strong enrichments in large‐ion lithophile elements (LILE;e.g., Rb, Ba, and Th) and depletions in high‐field‐strength elements (HFSE;e.g., Nb and Ta), indicating the Azhale granitoids are typically I‐type granite. In terms of isotopic composition, these rocks also have low εNd(t) values (−6.51 to −6.80) and high initial 87Sr/86Sr ratios (0.7078 to 0.7084) relative to melts derived from partial melting of ancient mafic lower crust. We considered that these rocks should be interpreted to have resulted from melting, assimilation, storage, and homogenization (MASH process) above subduction zones. In conclusion, combined with the published and our new data, we argued for the petrogenesis of Early Cretaceous arc‐related granitoids were due to the YZTO lithosphere subducted northward beneath the Lhasa Terrane.

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Age and petrogenesis of A-type granites in the middle segment of the Bangonghu–Nujiang suture, Tibetan plateau

Cited by 96 publications

References 34 publications

The geochronologic and geochemical constraints on the Early Cretaceous subduction magmatism in the central Lhasa subterrane, Tibet

The geochronologic and geochemical constraints on the Early Cretaceous subduction magmatism in the central Lhasa subterrane, Tibet

Tectono-magmatic evolution of the Gaoligong belt, southeastern margin of the Tibetan plateau: Constraints from granitic gneisses and granitoid intrusions

Early Cretaceous arc granitoids from the central Lhasa subterrane: Production of the northward subduction of Yarlung Zangbo Neo‐Tethyan Ocean?

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