Two Cenozoic tectonic events of N–S and E–W extension in the Lhasa Terrane: Evidence from geology and geochronology

Huang, Feng; Xu, Ji‐Feng; Chen, Jianlin; Wu, Jianbin; Zeng, Yunbo; Xiong, Qiu-Wei; Chen, Xuefeng; Yu, Hua-Zhong

doi:10.1016/j.lithos.2015.08.014

Cited by 26 publications

(26 citation statements)

References 94 publications

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“…The individual Daju mafic dikes are variable in size, but are all parallel to each other and E–W trending (Figures a and b), parallel to the IYZS. The latter orientation is consistent with the orientation of mafic dikes in other areas of the Lhasa Terrane (e.g., Dazi and Linzhou, Ding et al, ; Huang et al, ; Yue & Ding, ). These mafic dikes mainly intruded into granitic and dioritic intrusive bodies (Figures a and c).…”

Section: Sample Descriptionssupporting

confidence: 83%

“…As discussed above, their intraplate‐like geochemistry (Figure ) precludes a subduction‐related setting for the ∼57 Ma mafic dikes. In addition, emplacement of these mafic magmas into the crust as E–W trending dikes possibly reflects mantle upwelling in an extensional environment, similar to the mafic dikes found in the Linzhou and Dazi areas in southern Tibet (Ding et al, ; Huang et al, ; Yue & Ding, ). Dry asthenosphere can only melt when the lithosphere is sufficiently thin (∼80 km, McKenzie & Bickle, ).…”

Section: Discussionmentioning

confidence: 53%

“…Magmatic rocks with Cenozoic ages mainly belong to the island arc‐type felsic suite, which is ubiquitous throughout the entire southern Lhasa Subterrane (Figure b) (Chung et al, ; Huang et al, ; Ji et al, ; Wen et al, ). The mafic dikes are also observed in Dazi (38–42 Ma, Gao et al, ) in the southern Lhasa Subterrane, and in Linzhou (∼52.9 Ma, Yue & Ding, ) and Dangxung (∼54 Ma, Zhao et al, ) within the central Lhasa Subterrane.…”

Section: Discussionmentioning

confidence: 99%

“…The mafic dikes are also observed in Dazi (38–42 Ma, Gao et al, ) in the southern Lhasa Subterrane, and in Linzhou (∼52.9 Ma, Yue & Ding, ) and Dangxung (∼54 Ma, Zhao et al, ) within the central Lhasa Subterrane. Furthermore, Huang et al () constrained the timing of Dazi mafic dikes was between 53 and 60 Ma, based on the cross relationship between the felsic rocks and the mafic dikes. Collectively, the mafic samples from Daju belong to the relatively old Cenozoic mafic dikes within the Lhasa Terrane.…”

Section: Discussionmentioning

confidence: 99%

“…Mesozoic magmatic and sedimentary rocks are ubiquitous in the central and northern Lhasa subterranes (Figure b) (Coulon et al, ; Q. Wang et al, ; Zhu et al, ). The southern Lhasa Subterrane is mainly composed of Jurassic‐Miocene Gangdese batholiths and the Paleocene‐Eocene Linzizong volcanic succession (Dong et al, ; Huang et al, ; Ji et al, ; Kang et al, ; Lee et al, ; Li et al, ; Mo et al, ; Zhu et al, ), the latter consists of Dianzhong, Nianbo, and Pana formation. The sedimentary cover in the southern Lhasa Subterrane is limited, and is mainly of Late Triassic‐Cretaceous age (Zhu et al, ).…”

Section: Geological Backgroundmentioning

confidence: 99%

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Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

Huang

Zeng

et al. 2017

Geochem Geophys Geosyst

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Oceanic slab breakoff significantly affects the thermal regime of the lithosphere during continental collision. This often triggers extension‐related mafic magmatism and crustal melting. It is generally accepted that the Neo‐Tethyan lithosphere subducted beneath the southern Lhasa Subterrane, resulting in the formation of the Gangdese magmatic arc. However, the timing of slab breakoff is still disputed, due to a lack of evidence for extension‐related mafic magmatism. In this study, we provide comprehensive age, element and Sr–Nd–Hf isotopic data of mafic dikes, felsic intrusions, and enclaves from the Daju area, southern Lhasa Subterrane. The timing of mafic dikes and granitoids are contemporaneous at circa 57 Ma. The mafic dikes are characterized by high Th/U, and Zr/Y ratios, their geochemistry indicates an intraplate affinity rather than arc magmas. Furthermore, the mafic dikes show strongly variable igneous zircon ɛHf(t), and lower whole‐rock ɛNd(t) than granitoids. This evidence suggests that the mafic dikes represent asthenosphere‐derived melts contaminated by various degrees of ancient lithosphere. However, the granitoids were directly derived from the juvenile lower crust. Given the abrupt decrease in the convergence rate between India and Asia, and the surface uplift and sedimentation cessation in the southern Lhasa Subterrane in the early Cenozoic, the occurrence of synchronous mafic dikes and granitoids is best explained by a slab breakoff model. The occurrence of intraplate‐type magmas likely corresponds to the magmatic expression of the initial stage of Neo‐Tethyan slab breakoff. The slab breakoff concept also explains the onset of the magmatic “flare‐up” and crustal growth after 57 Ma.

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Section: Sample Descriptionssupporting

confidence: 83%

Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

See 3 more Smart Citations

Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

Huang

Zeng

et al. 2017

Geochem Geophys Geosyst

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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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Neo‐Tethyanslab tearing constrained by PalaeoceneN‐MORB‐like magmatism in southern Tibet

Tian

Huang

et al. 2020

Geological Journal

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Southern Tibet is a key region for investigating the magmatism that occurredduring the collision between India and Asia. The break‐off of the Neo‐Tethyan slab, after the onset of continental collision at ca. 65–60 Ma, affected the lithospheric thermal regime and led to a series of magmatic and tectonic events. Many magmatic rocks generated by slab break‐off have been reported in southern Tibet; however, which of these record the initial slab break‐off (i.e., slab tearing) is still an open question. The Lianxiang gabbros, which intrude an ophiolite in central‐southern Tibet, provide an ideal opportunity to investigate the footprint of the initial slab break‐off. Zircon U–Pb ages show that the Lianxiang gabbros crystallized at 57–53 Ma, coeval with other mafic dikes in southern Tibet. The Lianxiang gabbros are characterized by high Na2O (2.13–5.42 wt%), Al2O3(13.86–17.13 wt%), and V (188–346 ppm) contents and moderate Mg# (40.8–65.9). The gabbrosare slightly depleted in light rare earth elements [LREE; (La/Yb)N= 0.45–0.76], similar to normal mid‐ocean ridge basalt (N‐MORB). They also have low87Sr/86Sriratios (0.703538–0.705698) and highεNd(t) values (9.49–10.68), indicating that they were derived mainly from a shallow asthenospheric mantle source. Combining our results with data from other magmatism at ~57 Ma in the southern Lhasa Terrane, we propose that the N‐MORB‐type rocks reflect the tearing of the Neo‐Tethyan slab. The process of slab break‐off differed between western and eastern southern Tibet, possibly as a result of different lithospheric structures and compositions.

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Two Cenozoic tectonic events of N–S and E–W extension in the Lhasa Terrane: Evidence from geology and geochronology

Cited by 26 publications

References 94 publications

Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

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

Neo‐Tethyanslab tearing constrained by PalaeoceneN‐MORB‐like magmatism in southern Tibet

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