Late Cenozoic thrusting of major faults along the central segment of Longmen Shan, eastern Tibet: Evidence from low-temperature thermochronology

Tan, Xibin; Xu, Xiwei; Lee, Yuan-Hsi; Lu, Renqi; Liu, Yiduo; Xu, Chong; Li, Kang; Yu, Guihua; Kang, Wenjun

doi:10.1016/j.tecto.2017.05.016

Cited by 54 publications

(48 citation statements)

References 52 publications

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“…This change is interpreted to be the response to the isostatic rebound since the Mesozoic (Y. Li et al, ). Low‐temperature thermochronology data have revealed that the eastern TP has undergone rapid exhumation since the late Cenozoic (Godard et al, ; Richardson et al, ; Tan et al, , ; Tian et al, ; E. Wang et al, ). It has been estimated that the LMS was denuded ~7–10 km during the Cenozoic (B. Deng et al, ; Tan et al, ), which resulted in the exposure of Precambrian metasedimentary or igneous rocks (Burchfiel et al, ; S.F.…”

Section: Discussionmentioning

confidence: 99%

Three‐Dimensional Model of the Lithospheric Structure Under the Eastern Tibetan Plateau: Implications for the Active Tectonics and Seismic Hazards

Liu

et al. 2019

Tectonics

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Details of lithospheric structures in three‐dimensions (3‐D) are key to understanding the dynamics of crustal deformation and earthquakes in active orogenic systems. In this study, we develop a 3‐D model of the eastern Tibetan Plateau using the Skua‐Gocad software based on the latest Rayleigh wave tomography. We perform a quantitative modeling workflow to map the details of the Moho discontinuities and the high‐velocity anomalies. Then, we integrate the topography, major active faults, large earthquakes, and crustal Poisson's ratios to analyze the relationship between the shallow and deep structures of this region. Our study shows that the Moho is generally coupled with the topography. A steep Moho ramp exists under the plateau margin and its surface projection intersects the Longmen Shan (LMS) at a low oblique angle (~22°). Active deformation and large earthquakes are related to the steep Moho ramp under the plateau margin. Moreover, based on a 3‐D model of the Poisson's ratio perturbations, we find that deformation across the central LMS is characterized as a crocodile‐type wedge in the crust and lithospheric mantle, due to the resistance of the Yangtze craton and isostatic rebound. We suggest that a tectonic wedging model that contains both the upper‐crust thrusting and lower‐crustal thickening contribute to the LMS orogeny. Three‐dimensional visualization of the lithospheric structure is well suited to reveal the different levels of deformation and their relationships. Quantitative modeling methods provide effective constraints on the active blocks in the eastern Tibetan Plateau.

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Section: Discussionmentioning

confidence: 99%

Three‐Dimensional Model of the Lithospheric Structure Under the Eastern Tibetan Plateau: Implications for the Active Tectonics and Seismic Hazards

Liu

et al. 2019

Tectonics

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“…Low‐temperature thermochronology data obtained on the Pengguan, Baoxing, Xuelongbao, and Tonghua crystalline massifs (slices of the South China basement) document a phase of exhumation of the belt since ca. 30 Ma (Godard et al, ; Kirby et al, ; Tan et al, ; Wang et al, 2012). The shortening accommodated since the Oligocene has been estimated at ~35 km at the front of the LMS (Hubbard & Shaw, ; Hubbard et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Mesozoic Along‐Strike Tectonometamorphic Segmentation of Longmen Shan (Eastern Tibetan Plateau)

et al. 2018

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The Longmen Shan belt (eastern border of the Tibetan plateau) constitutes a tectonically active region as demonstrated by the occurrence of the unexpected 2008 Mw 7.9 Wenchuan and 2013 Mw 6.6 Lushan earthquakes in the central and southern parts of the belt, respectively. These events revealed the necessity of a better understanding of the long‐term geological evolution of the belt and its effect on the present dynamics and crustal structure. New structural and thermobarometric data offer a comprehensive data set of the paleotemperatures across the belt and P‐T estimates for low‐grade metamorphic domains. In the central Longmen Shan, two metamorphic jumps of 150–200 °C, 5–6 kbar and ~50 °C, 3–5 kbar acquired during the Early Mesozoic are observed across the Wenchuan and Beichuan faults, respectively, attesting to their thrusting movement and unrevealing a major decollement between the allochtonous Songpan‐Garze metasedimentary cover (at T > 500 °C) and the autochtonous units and the basement (T < 400 °C). In the southern Longmen Shan, the only greenschist facies metamorphism is observed both in the basement (360 ± 30 °C, 6 ± 2 kbar) and in the metasedimentary cover (350 ± 30 °C, 3 ± 1 kbar). Peak conditions were reached at ca. 80–60 Ma in the basement and ca. 55–33 Ma in the cover, ca. 50 Ma after the greenschist facies metamorphic overprint observed in the central Longmen Shan (ca. 150–120 Ma). This along‐strike metamorphic segmentation coincides well with the present fault segmentation and reveals that the central and southern Longmen Shan experienced different tectonometamorphic histories since the Mesozoic.

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“…Compared with the HKSS, the higher topography in the LMSS causes stronger normal stresses on the BYF (Figure ), which increases the friction along this subsegment (given a uniform coefficient of internal friction in the central LTB; Dahlen et al, ). Since it is not favorable to accommodate the strains solely on the BYF, thrust slips are thus partitioned onto the JGF in the LMSS, resulting in the along‐strike variation of the long‐term activity and coseismic slip on the JGF (Lu et al, ; Tan, Xu, Lee, et al, ; Tan, Xu, & Lu, ). Therefore, the topographic variations in the hanging‐wall block of the BYF play a major role in producing the long‐term fault activity and coseismic slip differences between the LMSS and HKSS.…”

Section: Discussionmentioning

confidence: 99%

“…The central segment of LTB contains three major faults, namely, from west to east, the Wenchuan‐Maoxian fault, Beichuan‐Yingxiu fault (BYF), and Jiangyou‐Guanxian fault (JGF; Figures and ). They are NW‐dipping, SE‐vergent, imbricated thrust faults with a generally foreland‐ward propagation history based on seismic‐ and field‐based analyses and low‐temperature thermochronology (Hubbard & Shaw, ; Lu et al, ; Tan, Xu, Lee, et al, ). Surface exposures consist of predominantly Precambrian crystalline basement rocks (the Pengguan massif and Xuelongbao massif in the central LTB) as well as Paleozoic marine sedimentary sequences (Figure ; S. G. Liu et al, ; Ma & Yang, ).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Previous studies also highlighted the relationships between the topography and fault activity by lateral comparison between the northern, central, and southern segments of the LTB (Gao et al, ; Sun et al, ; H. Zhang et al, ; Figure ). However, the chicken‐or‐egg debate still holds due to the lack of a control group in these studies, because both the landscape and total shortening strains vary, sometimes significantly, among the segments of LTB, which weakens the argument for or against either mechanism (Godard et al, , ; Tan, Xu, Lee, et al, ; Tan, Xu, & Lu, ; E. Wang et al, ). In fact, a large spatial scale tends to reduce the consistency of both the external and internal forces, particularly the latter one, because of the structural and mechanical heterogeneities within the crust.…”

Section: Introductionmentioning

confidence: 99%

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Topographic Loads Modified by Fluvial Incision Impact Fault Activity in the Longmenshan Thrust Belt, Eastern Margin of the Tibetan Plateau

et al. 2018

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Whether external or internal forces of the Earth control the behaviors of upper‐crustal faults in a fold‐and‐thrust belt has been debated for decades. The Longmenshan thrust belt (LTB) along the eastern margin of the Tibetan Plateau may provide insights into such a debate, as the central segment of the LTB has relatively uniform shortening strains yet various fluvial incision capability along the strike. This tectonic setting enables a better assessment of the effects of external forces on fault activity. We analyzed the variations of topography, fluvial incision intensity, coseismic slips, and coseismic landslides along the central LTB. The Longmen subsegment in the northern half has higher elevation and lower fluvial incision intensity than the Hongkou subsegment in the south. We calculated the topographic stresses on the faults ruptured during the 2008 Wenchuan earthquake and found topographic introduced normal stress increase may explain the coseismic slip partitioning onto two subfaults along the Longmen subsegment. Our results indicate that fluvial incision may have produced the along‐strike variations of the topography, which may further produce the different rupture behavior. In addition, the mean hillslope angle along the central LTB appeared to be at the critical condition prior to the 2008 Wenchuan earthquake and reduced significantly by the earthquake, indicating that geomorphic indices may vary with different stages in an earthquake cycle. Therefore, scrutinizing the mean hillslope angle and other geomorphic indices may help identify potential seismic hazards in an active fault system.

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Late Cenozoic thrusting of major faults along the central segment of Longmen Shan, eastern Tibet: Evidence from low-temperature thermochronology

Cited by 54 publications

References 52 publications

Three‐Dimensional Model of the Lithospheric Structure Under the Eastern Tibetan Plateau: Implications for the Active Tectonics and Seismic Hazards

Three‐Dimensional Model of the Lithospheric Structure Under the Eastern Tibetan Plateau: Implications for the Active Tectonics and Seismic Hazards

The Mesozoic Along‐Strike Tectonometamorphic Segmentation of Longmen Shan (Eastern Tibetan Plateau)

Topographic Loads Modified by Fluvial Incision Impact Fault Activity in the Longmenshan Thrust Belt, Eastern Margin of the Tibetan Plateau

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