Direct structural evidence of Indian continental subduction beneath Myanmar

Zheng, Tianyu; He, Yumei; Ding, Lin; Jiang, Mingming; Ai, Yinshuang; Mon, Chit Thet; Hou, Guichen; Sein, Kyaing; Thant, Myo

doi:10.1038/s41467-020-15746-3

Cited by 66 publications

(40 citation statements)

References 40 publications

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“…the north, which is supported by a recent RF study, suggesting deep subduction of the Indian continental plate north of 21°N (Zheng et al, 2020). Whereas the Andaman slab is subducted into the lower mantle, the Burma slab is broken off, as also seen by seismic tomography (e.g., Pesicek et al, 2010).…”

Section: 1029/2020gc009262supporting

confidence: 68%

Mantle Transition Zone Structure Beneath Myanmar and Its Geodynamic Implications

Bai

Yuan

et al. 2020

Geochem Geophys Geosyst

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Following the closure of the Neo-Tethys ocean, the Indian plate began to collide with the Eurasian plate in the Eocene (e.g., Molnar & Stock, 2009). One of the profound consequences is the formation of the Himalayan mountain belt and the Tibetan plateau. The convergent boundary extends along the Himalayan arc and is terminated to the east at the eastern Himalayan syntaxis, where it bends to the south, continues along the Burma arc, and connects to the Andaman-Sumatra arc, a site of oceanic subduction. While many seismic experiments have demonstrated that the Indian lithosphere is underthrusting northwards under Tibet (e.g., Kind et al., 2002; Nábělek et al., 2009), the detailed subduction geometry

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Section: 1029/2020gc009262supporting

confidence: 68%

Mantle Transition Zone Structure Beneath Myanmar and Its Geodynamic Implications

Bai

Yuan

et al. 2020

Geochem Geophys Geosyst

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“…Further south on the 25°N profile, the low Q anomalies between 0.2 and 5.0 Hz appears beneath the Red River Fault and Xiaojiang Fault (Figure 6c), likely to be the southward extension of the low Q anomalies beneath Western Sichuan and Central Yunnan. Low Q values in this frequency range can also be seen beneath the Myanmar block (Figure 6c and 6d), which is likely related to the eastward subduction of the underlying Indian plate (T. Zheng et al., 2020). The Myanmar block and Indian plate have low Q Lg at frequencies of less than ∼0.3 Hz (Figure 6c), and similar cases can also be found for the Sichuan Basin (Figure 6a) and Indian plate (Figure 6b).…”

Section: Resultsmentioning

confidence: 94%

“…In northern Myanmar, strong Lg attenuation with broadband Q less than ∼200 is also revealed, overlying the eastward subduction of the Indian plate. The subduction of the Indian plate involves not only the northward subduction beneath the Tibetan Plateau but also the eastward component beneath the Myanmar arc (T. Zheng et al., 2020). Its Wadati‐Benioff zone can be delineated by the seismicity down to ∼150 km (Stork et al., 2008).…”

Section: Discussionmentioning

confidence: 99%

“…By comparing to Western Himalayan Syntax, where the subduction occurred in the absence of upper crust, T. Zheng et al. (2020) suggested that the eastward subduction of the entire Indian continental crust was the consequence of both oblique collision and sideway extrusion. Analogously, the eastward subduction of Indian plate also plays an important role to the crustal deformation in the southeast Tibet Plateau, because the subsequent processes related to the subduction, including asthenosphere upwelling and slab retreating, could resulted in the weakened crust and extensional stress, probably decreasing the resistance to the escape of crustal material in the southeastern margin of Tibetan Plateau.…”

Section: Discussionmentioning

confidence: 99%

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Weak Crust in Southeast Tibetan Plateau Revealed by Lg‐Wave Attenuation Tomography: Implications for Crustal Material Escape

Zhao

Xie

et al. 2021

JGR Solid Earth

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The continuous convergence between the Indian and Eurasian plates caused massive lithospheric deformation in the Tibetan Plateau and led to excessive crustal material escaping through its southeastern margin. However, the mechanisms that accommodate the escaping materials and whether they intrude into the Indochina Peninsula are continually under debate. Seismic Lg waves mostly propagate within the crust waveguide with an amplitude decay that is sensitive to crustal material properties, such as temperature, partial melting, and fracture. Therefore, Lg attenuation can be a useful indicator of potential crustal material escape. In this study, we developed a high‐resolution broadband Lg attenuation model in this region between 0.05 and 10.0 Hz, with the resolution reaching 1° in regions with dense raypath coverage. Prominent low‐Q anomalies beneath the southeastern margin of the Tibetan Plateau, correlating with previously observed low velocity, high conductivity and high Poisson’s ratio, may indicate possible high temperature and/or partial melting within a relatively weak crust, and suggest a north‐south interconnected corridor for gravity‐driven material flow. Through our results and other geological and geophysical observations, a dynamic model is suggested here by combining shallow rigid block extrusion and deep viscous crustal flow to explain crustal material escape in the southeastern margin of the Tibetan Plateau. Additionally, neither shallow extrusion nor deep material flow enter the Indochina Peninsula based on the relatively high Q values, which indicate a stronger crust there.

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“…However, if the lower crust is too strong (>10 22 Pa·s), the whole crust undergoes pure shear thickening which results in coherent deformation and less developed shear zones. Thus, the absent SZ2 may be potentially explained by different deformation styles due to along‐strike rheological heterogeneities between the east‐west (Bischoff & Flesch, 2019; Chen et al, 2017; Zheng et al, 2020) and the north‐south (Huangfu et al, 2018) Tibetan terranes. Notably, the effective viscosities of upper and lower crust in our reference model are consistent with previous models which account for normal faulting and viscous buckling (Bischoff & Flesch, 2018; Flesch et al, 2001) in Tibet.…”

Section: Discussionmentioning

confidence: 99%

Lower Crustal Rheology Controls the Development of Large Offset Strike‐Slip Faults During the Himalayan‐Tibetan Orogeny

Yang

Kaus

et al. 2020

Geophysical Research Letters

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The mechanism of crustal deformation and the development of large offset strike-slip faults during continental collision, such as the India-Eurasia zone, remains poorly understood. Previous mechanical models were simplified which are either (quasi-)2-D approximations or made the a priori assumption that the rheology of the lithosphere was either purely viscous (distributed deformation) or purely localized. Here we present three-dimensional visco-elasto-plastic thermo-mechanical simulations, which can produce both distributed and highly localized deformation, to investigate crustal deformation during continental indentation. Our results show that large-scale shear zones develop as a result of frictional plasticity, which have many similarities with observed shear zones. Yet localized deformation requires both a strong upper crust (>10 22 Pa•s) and a moderately weak middle/lower crust (~10 20 Pa•s) in Tibet. The brittle shear zones in our models develop low viscosity zones directly beneath them, consistent with geological observations of exhumed faults, and geophysical observations across active faults. Plain Language Summary Large offset strike-slip faults are one of the key surface features of continental collision, such as in Tibet. These narrow belts of strike-slip faults accommodate strong deformation, and deciphering their mechanism of formation helps to understand the complex dynamics of India-Eurasia collision. Yet previous models developed to address this either assumed simplified rheologies or employed low numerical resolutions that is insufficient to simulate the spontaneous formation of localized zones. Here, we present high-resolution 3-D visco-elasto-plastic thermo-mechanical models that simulate the formation of large-scale strike-slip faults during Indian indentation, while also taking distributed deformation into account. Our simulations show that a combination of a strong upper crust and a moderately weak middle/lower crust produces faults that are, to first order, consistent with observed ones in the Tibet region. Localized deformation usually initiates at the brittle-ductile transition, and a weak middle/lower crust facilitates subsequent shear localization such that the shear zones cut through the whole crust. The craton-like strong terranes can sustain large stresses and initiate large offset faults along their boundaries.

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Direct structural evidence of Indian continental subduction beneath Myanmar

Cited by 66 publications

References 40 publications

Mantle Transition Zone Structure Beneath Myanmar and Its Geodynamic Implications

Mantle Transition Zone Structure Beneath Myanmar and Its Geodynamic Implications

Weak Crust in Southeast Tibetan Plateau Revealed by Lg‐Wave Attenuation Tomography: Implications for Crustal Material Escape

Lower Crustal Rheology Controls the Development of Large Offset Strike‐Slip Faults During the Himalayan‐Tibetan Orogeny

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