Exhumation History Along the Muli Thrust—Implication for Crustal Thickening Mechanism in Eastern Tibet

P. Pitard; A. Replumaz; M. L. Chevalier; P. H. Leloup; M. Bai; M. P. Doin; C. Thieulot; X. Ou; M. Balvay; H. Li

doi:10.1029/2021GL093677

Exhumation History Along the Muli Thrust—Implication for Crustal Thickening Mechanism in Eastern Tibet

P. Pitard^*
, A. Replumaz
, M. L. Chevalier
, P. H. Leloup
, M. Bai
, M. P. Doin
, C. Thieulot
, X. Ou
, M. Balvay
, H. Li

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Thrusting implication in the crustal thickening history of eastern Tibet is highly debated. The ∼250 km-long Muli thrust of the Yalong thrust belt in SE Tibet is a major Miocene structure with a pronounced topographic step (∼2,000 m). Using thermo-kinematic modeling based on thermochronology data, we constrain the crustal geometry of the thrust as being steep (>70°) at the surface, in agreement with field observations, and flattening at depth (≥20 km) on an intra-crustal décollement. Thrusting motion on the fault shows a velocity of 0.2 ± 0.06 km/Ma since 50 Ma, followed by an acceleration at a rate of 0.6 ± 0.08 km/Ma starting at 12.5 ± 1 Ma, yielding a total of ∼15 km of exhumed crust. Deeper, deformation may be localized through a ductile shear zone, and be related to the ∼15 km Moho step and shear wave velocity contrast imaged by tomography beneath the Yalong thrust belt.

Original language	English
Article number	e2021GL093677
Pages (from-to)	1-10
Number of pages	10
Journal	Geophysical Research Letters
Volume	48
Issue number	14
DOIs	https://doi.org/10.1029/2021GL093677
Publication status	Published - 28 Jul 2021

Bibliographical note

Funding Information:
This work was supported by the TelluS Program of CNRS/INSU, ISTerre, LGL‐TPE, Agence Nationale de Recherche (ANR “Tibetan Orchestra”), National Natural Science Foundation of China [NSFC 42020104007, 41941016] and the Second Tibetan Plateau Scientific Expedition of the Ministry of Science and Technology of China [2019QZKK0901].

Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.

Funding

This work was supported by the TelluS Program of CNRS/INSU, ISTerre, LGL‐TPE, Agence Nationale de Recherche (ANR “Tibetan Orchestra”), National Natural Science Foundation of China [NSFC 42020104007, 41941016] and the Second Tibetan Plateau Scientific Expedition of the Ministry of Science and Technology of China [2019QZKK0901].

Keywords

crustal structure of Tibet
formation Tibet
low-temperature thermochronology
Muli thrust
Tibetan Plateau
Yalong thrust belt

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10.1029/2021GL093677

2021GL093677Final published version, 4.52 MBLicence: Taverne

Cite this

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title = "Exhumation History Along the Muli Thrust—Implication for Crustal Thickening Mechanism in Eastern Tibet",

abstract = "Thrusting implication in the crustal thickening history of eastern Tibet is highly debated. The ∼250 km-long Muli thrust of the Yalong thrust belt in SE Tibet is a major Miocene structure with a pronounced topographic step (∼2,000 m). Using thermo-kinematic modeling based on thermochronology data, we constrain the crustal geometry of the thrust as being steep (>70°) at the surface, in agreement with field observations, and flattening at depth (≥20 km) on an intra-crustal d{\'e}collement. Thrusting motion on the fault shows a velocity of 0.2 ± 0.06 km/Ma since 50 Ma, followed by an acceleration at a rate of 0.6 ± 0.08 km/Ma starting at 12.5 ± 1 Ma, yielding a total of ∼15 km of exhumed crust. Deeper, deformation may be localized through a ductile shear zone, and be related to the ∼15 km Moho step and shear wave velocity contrast imaged by tomography beneath the Yalong thrust belt.",

keywords = "crustal structure of Tibet, formation Tibet, low-temperature thermochronology, Muli thrust, Tibetan Plateau, Yalong thrust belt",

author = "P. Pitard and A. Replumaz and Chevalier, \{M. L.\} and Leloup, \{P. H.\} and M. Bai and Doin, \{M. P.\} and C. Thieulot and X. Ou and M. Balvay and H. Li",

note = "Funding Information: This work was supported by the TelluS Program of CNRS/INSU, ISTerre, LGL‐TPE, Agence Nationale de Recherche (ANR “Tibetan Orchestra”), National Natural Science Foundation of China [NSFC 42020104007, 41941016] and the Second Tibetan Plateau Scientific Expedition of the Ministry of Science and Technology of China [2019QZKK0901]. Publisher Copyright: {\textcopyright} 2021. American Geophysical Union. All Rights Reserved.",

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AU - Pitard, P.

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AU - Chevalier, M. L.

AU - Leloup, P. H.

AU - Bai, M.

AU - Doin, M. P.

AU - Thieulot, C.

AU - Ou, X.

AU - Balvay, M.

AU - Li, H.

N1 - Funding Information: This work was supported by the TelluS Program of CNRS/INSU, ISTerre, LGL‐TPE, Agence Nationale de Recherche (ANR “Tibetan Orchestra”), National Natural Science Foundation of China [NSFC 42020104007, 41941016] and the Second Tibetan Plateau Scientific Expedition of the Ministry of Science and Technology of China [2019QZKK0901]. Publisher Copyright: © 2021. American Geophysical Union. All Rights Reserved.

PY - 2021/7/28

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N2 - Thrusting implication in the crustal thickening history of eastern Tibet is highly debated. The ∼250 km-long Muli thrust of the Yalong thrust belt in SE Tibet is a major Miocene structure with a pronounced topographic step (∼2,000 m). Using thermo-kinematic modeling based on thermochronology data, we constrain the crustal geometry of the thrust as being steep (>70°) at the surface, in agreement with field observations, and flattening at depth (≥20 km) on an intra-crustal décollement. Thrusting motion on the fault shows a velocity of 0.2 ± 0.06 km/Ma since 50 Ma, followed by an acceleration at a rate of 0.6 ± 0.08 km/Ma starting at 12.5 ± 1 Ma, yielding a total of ∼15 km of exhumed crust. Deeper, deformation may be localized through a ductile shear zone, and be related to the ∼15 km Moho step and shear wave velocity contrast imaged by tomography beneath the Yalong thrust belt.

AB - Thrusting implication in the crustal thickening history of eastern Tibet is highly debated. The ∼250 km-long Muli thrust of the Yalong thrust belt in SE Tibet is a major Miocene structure with a pronounced topographic step (∼2,000 m). Using thermo-kinematic modeling based on thermochronology data, we constrain the crustal geometry of the thrust as being steep (>70°) at the surface, in agreement with field observations, and flattening at depth (≥20 km) on an intra-crustal décollement. Thrusting motion on the fault shows a velocity of 0.2 ± 0.06 km/Ma since 50 Ma, followed by an acceleration at a rate of 0.6 ± 0.08 km/Ma starting at 12.5 ± 1 Ma, yielding a total of ∼15 km of exhumed crust. Deeper, deformation may be localized through a ductile shear zone, and be related to the ∼15 km Moho step and shear wave velocity contrast imaged by tomography beneath the Yalong thrust belt.

KW - crustal structure of Tibet

KW - formation Tibet

KW - low-temperature thermochronology

KW - Muli thrust

KW - Tibetan Plateau

KW - Yalong thrust belt

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M1 - e2021GL093677

ER -

Exhumation History Along the Muli Thrust—Implication for Crustal Thickening Mechanism in Eastern Tibet

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Bibliographical note

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Keywords

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