Melting conditions in the modern Tibetan crust since the Miocene

Chen, Jinyu; Gaillard, Fabrice; Villaros, Arnaud; Yang, Xiao‐Song; Laumonier, Mickaël; Jolivet, Laurent; Unsworth, Martyn; Hashim, Leïla; Scaillet, Bruno; Richard, Guillaume

doi:10.1038/s41467-018-05934-7

Cited by 42 publications

(59 citation statements)

References 70 publications

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“…Furthermore, the existence of the mid‐crustal LVZ is also suggested by the RF results beneath the northwest Himalaya (Hazarika et al., 2017) and along the Hi‐CLIMB profile at 85°E (Duputel et al., 2016). We suggest that the formation of this mid‐crustal LVZ observed in the Tethyan Himalaya could be due to the presence of crustal dehydration partial melting, which is justified by the conclusion drawn from a comparison between the experimental conductivity measurements of Himalayan Miocene metamorphic rocks and the present geophysical MT data (J. Y. Chen et al., 2018). The results of 3D thermomechanical modeling indicate that radioactive, shear and basal heating during crustal thickening provide important heat sources for generating such mid‐crustal partial melting (L. Chen et al., 2019).…”

Section: Discussionsupporting

confidence: 69%

Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions

Liu

Yuan

et al. 2021

JGR Solid Earth

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The Himalaya, extending for almost 2,500 km along strike, resulted from the India-Asia collision and convergence beginning at ∼65 Ma (DeCelles et al., 2014; Ding et al., 2005). Global positioning system (GPS) measurements estimate a shortening rate of ∼15 mm/year along the Himalaya (Zheng et al., 2017), leading to the development of an upper crustal fold-thrust belt. Three major north-dipping thrust faults, namely, the Main Frontal Thrust (MFT), Main Boundary Thrust (MBT) and Main Central Thrust (MCT), merge with the Main Himalayan Thrust (MHT) at depth. These thrust faults together with the South Tibetan Detachment System (STDS) divide the Himalaya from south to north into the sub-Himalaya, lesser Himalaya, higher (greater) Himalaya, and Tethyan Himalaya (DeCelles et al., 2014; Yin, 2006). Over the past decades, seismological images from various south-north profiles have clearly revealed that the Indian plate underthrusts the Himalaya along the MHT, which separates the overlying Himalayan fold-thrust wedge from the downgoing Indian lithosphere (

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Section: Discussionsupporting

confidence: 69%

Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions

Liu

Yuan

et al. 2021

JGR Solid Earth

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“…Recent studies show that dehydration melting may result in melt water content of as high as 6%-8% (J. Chen et al, 2018) in the southern Tibetan Plateau. Conductivity models with laboratory constraints also predict a similarly high level of water content (7%-9%) in the lower crust (Comeau et al, 2016;Laumonier et al, 2014).…”

Section: Water Contentmentioning

confidence: 99%

“…J. Chen et al (2018) developed a similar empirical model for the estimation of the melt/fluid conductivity using the Arrhenius equation. Figure 6a shows the calculated fluid conductivity from both the Guo et al (2018) and J.…”

Section: Melt Fraction Estimationmentioning

confidence: 99%

“…Experimental constrains suggest bound H 2 O content of 5–6 wt.% (Patino Douce & Harris, 1998) or >6 wt.% (Hashim et al, 2013) for water dissolved in Himalayan granite magmas in the late Oligocene to Miocene times. Recent studies show that dehydration melting may result in melt water content of as high as 6%–8% (J. Chen et al, 2018) in the southern Tibetan Plateau. Conductivity models with laboratory constraints also predict a similarly high level of water content (7%–9%) in the lower crust (Comeau et al, 2016; Laumonier et al, 2014).…”

Section: Rheology Constraints From Conductivity Modelmentioning

confidence: 99%

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Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

et al. 2020

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The ongoing India-Asia collision since the Paleogene created the Tibetan Plateau, the most prominent elevated plateau on our planet. This convergence also contributed to the formation of two distinct types of active surface deformation of the plateau, namely, north-south trending normal fault systems and "conjugate" strike-slip fault systems. The tectonics and geodynamic mechanism(s) behind this curious combination are still unclear, despite numerous theories proposed over past decades. Here we present a new three-dimensional, lithospheric-scale, electrical conductivity model with unprecedented resolution of the central part of Tibetan Plateau derived from the SINOPROBE magnetotelluric array data set and discuss its inferences related to this question. Our model reveals contrasting conductivity structures corresponding to the surface deformation patterns, namely, highly conductive lower crustal anomalies beneath the graben systems in the Lhasa and Qiangtang terranes and moderately resistive crustal features in the strike-slip region near Bangong-Nujiang Suture Zone. With the help of experimentally calibrated constraints between conductivity and melt fraction, the conductivity model and the inferred lateral viscosity distribution together suggest a weak lower crust beneath the graben regions, compared to a stronger crustal rheology associated with the strike-slip zone. Here we expand the previously proposed "extensional extrusion" tectonic model in central Tibet to interpret our conductivity model and other geophysical/geodesic observations. The weak rheology under a N-S directed primary stress may have caused the east-west extension of the graben regions, which further aides the eastward extrusion of the conjugate strike-slip zone and eventually shapes the surface deformation of central Tibetan Plateau into its current, complex pattern. Plain Language Summary The collision between the Indian and Asian continents built the Tibetan Plateau, the highest plateau in the world. This active collision also formed distinctly different types of large-scale geological structures on the plateau surface. Among the most important features on the plateau, the origin of the N-S directed normal (or spreading) fault zones in two regions named Lhasa and Qiangtang, and the NW/SE directed slip fault zones between these two regions are still unclear. In order to understand the generation of those structures, we use a geophysical imaging method called magnetotellurics to measure the naturally occurring electromagnetic waves in the earth. We model and analyze these magnetotellurics data to obtain the deep structure beneath those surface structures, using sophisticated computer codes. We find that the two dominant but different types of those structures are most likely due to the different strengths of the deep crust. This strength difference can lead to a mechanical stress contrast, which further builds the distinctly different surface structures. These kinds of deep physical structure differences have not been detected for the area bef...

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“…Zircons originating from the Indian crust and found in magmatic rocks close to the suture in the Himalayan belt suggest that some magmatism may well be partially derived from subducted continental crust (Bouilhol et al, ), consistent with the Sr‐Nd‐Pb isotope systematics of magmatism further north (Guo et al, ). Missing compositional variations or small‐scale processes at shallower depth (e.g., faulting and shear heating) in our models prevent predictions of melting at shallow depths, such as crustal melting due to thickening of the overriding crust during collision (e.g., Chen et al, ; Wang et al, ).…”

Section: Discussionmentioning

confidence: 99%

The Role of Crustal Buoyancy in the Generation and Emplacement of Magmatism During Continental Collision

Schliffke

Hunen

Magni

et al. 2019

Geochem Geophys Geosyst

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During continental collision, considerable amounts of buoyant continental crust subduct to depth and subsequently exhume. Whether various exhumation paths contribute to contrasting styles of magmatism across modern collision zones is unclear. Here we present 2D thermomechanical models of continental collision combined with petrological databases to investigate the effect of the main contrasting buoyancy forces, in the form of continental crustal buoyancy versus oceanic slab age (i.e., its thickness). We specifically focus on the consequences for crustal exhumation mechanisms and magmatism. Results indicate that it is mainly crustal density that determines the degree of steepening of the subducting continent and separates the models' parameter space into two regimes. In the first regime, high buoyancy values (∆ρ > 500 kg/m3) steepen the slab most rapidly (to 45–58°), leading to opening of a gap in the subduction channel through which the subducted crust exhumes (“subduction channel crustal exhumation”). A shift to a second regime (“underplating”) occurs when the density contrast is reduced by 50 kg/m3. In this scenario, the slab steepens less (to 37–50°), forcing subducted crust to be placed below the overriding plate. Importantly, the magmatism changes in the two cases: Crustal exhumation through the subduction channel is mainly accompanied by a narrow band of mantle melts, while underplating leads to widespread melting of mixed sources. Finally, we suggest that the amount (or density) of subducted continental crust, and the resulting buoyancy forces, could contribute to contrasting collision styles and magmatism in the Alps and Himalayas/Tibet.

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Melting conditions in the modern Tibetan crust since the Miocene

Cited by 42 publications

References 70 publications

Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions

Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions

Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

The Role of Crustal Buoyancy in the Generation and Emplacement of Magmatism During Continental Collision

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