Deep Mantle Dynamics in East Asia: Numerical Simulation of Mantle Convection Based on Seismic Tomography

2020 ◽  
Author(s):  
Huai Zhang ◽  
Qunfan Zheng ◽  
Zhen Zhang
Keyword(s):  
East Asia ◽  
Seismic Tomography ◽  
Upper Mantle ◽  
Continental Collision ◽  
Indian Plate ◽  
Mantle Flow ◽  
Lithospheric Deformation ◽  
Mantle Dynamics ◽  
Asthenospheric Mantle ◽  
Deep Mantle

<p>East Asia is a tectonically active area on earth and has a complicated lithospheric deformation due to the western continental collision from the cratonic Indian plate and the eastern oceanic subduction mainly from Pacific plate. Studies have suggested that the Indo–Asian continental collision may have driven significant lateral mantle flow, but the velocity, range and effect of the mantle flow remain uncertain. Hence, a series of 3-D numerical models are conducted in this study to reveal the impacts of the Indo–Asian collision on mantle dynamics beneath the East Asia, especially on the asthenospheric mantle. Global model domain encompasses the lithosphere, upper mantle and the lower mantle with different viscosity for each layer. A global temperature structure built from seismic tomography and absolute plate field are applied subsequently to get a better constraint of the initial temperature condition and surficial velocity boundary condition. Thus, the reasonable velocity and temperature distributions of upper mantle beneath East Asia at different depths are retrieved based on our 3-D global mantle flow simulations, and the key controlling parameters in shaping the present-day observed mantle structure are investigated. The results show different scales of convection beneath East Asia.</p><p>Our results suggest that Indo–Asian collision may have induced mantle flow beneath the Indian plate and the different velocity structures between the asthenosphere and lithosphere indicate the shear drag of asthenospheric mantle. That may explain the reason that Indo–Asian collision has occurred since 50 Ma, and this collision can still continue to accelerate in the Tibetan Plateau. The simulation results also show the lithospheric delamination and the induced mantle upwelling, which is consistent with the general understanding from previous observations. The Indian lithosphere and its asthenosphere move northward, while the Yunnan lithosphere and its asthenosphere move southward, that may reflect the differences in deep mantle dynamics between the eastern and western Himalayan Syntaxis.</p>

Mantle convection beneath East Asia under global mantle convection spherical framework

2020 ◽  
Author(s):  
Qunfan Zheng ◽  
Huai Zhang
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
Upper Mantle ◽  
Mantle Convection ◽  
Mantle Flow ◽  
The Tibetan Plateau ◽  
Mantle Structure ◽  
Lithospheric Deformation ◽  
Mantle Dynamics ◽  
Flow Models

<p>East Asia is a tectonically active area on earth and has a complicated lithospheric deformation due to the western Indo-Asian continental collision and the eastern oceanic subduction mainly from Pacific plate. Till now, mantle dynamics beneath this area is not well understood due to its complex mantle structure, especially in the framework of global spherical mantle convection. Hence, a series of numerical models are conducted in this study to reveal the key controlling parameters in shaping the present-day observed mantle structure beneath East Asia under 3-D global mantle flow models. Global mantle flow models with coarse mesh are firstly applied to give a rough constraint on global mantle convection. The detailed description of upper mantle dynamics of East Asia is left with regional refined mesh. A power-law rheology and absolute plate field are applied subsequently to get a better constraint on the related regional mantle rheological structure and surficial boundary conditions. Thus, the refined and reasonable velocity and stress distributions of upper mantle beneath East Asia at different depths are retrieved based on our 3-D global mantle flow simulations. The derived large shallow mantle flow beneath the Tibetan Plateau causes significant lithospheric shear drag and dynamic topography that result in prominent tectonic evolution of this area. And the Indo–Asian collision may have induced mantle flow beneath the Indian plate and the different velocity structures between the asthenosphere and lithosphere indicate the shear drag of asthenospheric mantle. That may explain the reason that Indo–Asian collision has occurred for 50 Ma, and this collision can still continue to accelerate uplift in the Tibetan plateau. Finally, we also consider the possible implementations of 3-D numerical simulations combined with global lithosphere and deep mantle dynamics so as to discuss the relevant influences.</p>

scholarly journals Feedbacks between a non-Newtonian upper mantle, mantle viscosity structure and mantle dynamics

2020 ◽  
Vol 224 (2) ◽  
pp. 961-972
Author(s):  
A G Semple ◽  
A Lenardic
Keyword(s):  
Upper Mantle ◽  
Lower Mantle ◽  
Mantle Convection ◽  
Mantle Flow ◽  
Mantle Dynamics ◽  
Plate Motions ◽  
Low Viscosity ◽  
Mantle Viscosity ◽  
Flow Feature ◽  
Mantle Rheology

SUMMARY Previous studies have shown that a low viscosity upper mantle can impact the wavelength of mantle flow and the balance of plate driving to resisting forces. Those studies assumed that mantle viscosity is independent of mantle flow. We explore the potential that mantle flow is not only influenced by viscosity but can also feedback and alter mantle viscosity structure owing to a non-Newtonian upper-mantle rheology. Our results indicate that the average viscosity of the upper mantle, and viscosity variations within it, are affected by the depth to which a non-Newtonian rheology holds. Changes in the wavelength of mantle flow, that occur when upper-mantle viscosity drops below a critical value, alter flow velocities which, in turn, alter mantle viscosity. Those changes also affect flow profiles in the mantle and the degree to which mantle flow drives the motion of a plate analogue above it. Enhanced upper-mantle flow, due to an increasing degree of non-Newtonian behaviour, decreases the ratio of upper- to lower-mantle viscosity. Whole layer mantle convection is maintained but upper- and lower-mantle flow take on different dynamic forms: fast and concentrated upper-mantle flow; slow and diffuse lower-mantle flow. Collectively, mantle viscosity, mantle flow wavelengths, upper- to lower-mantle velocities and the degree to which the mantle can drive plate motions become connected to one another through coupled feedback loops. Under this view of mantle dynamics, depth-variable mantle viscosity is an emergent flow feature that both affects and is affected by the configuration of mantle and plate flow.

Heterogeneous modification and reactivation of craton margin in northeast Asia: insight from teleseismic traveltime tomography of the Korean Peninsula

2020 ◽  
Author(s):  
Jung-Hun Song ◽  
Seongryong Kim ◽  
Junkee Rhie
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
Korean Peninsula ◽  
Velocity Structure ◽  
Northeast Asia ◽  
Continental Collision ◽  
P Wave ◽  
Mantle Dynamics ◽  
Traveltime Tomography ◽  
Yeongnam Massif

<p>Margins of craton lithosphere are prone to ongoing modification process. Marginal tectonism such as slab subduction, continental collision, and mantle dynamics significantly influence properties of lithosphere in various scales. Thus, constraints on the detailed properties of craton margin are essential to understand the evolution of continental lithosphere. The eastern margin of the Eurasian plate is a natural laboratory that allows us to study the strong effects from multiple episodes of continental collision and subduction of different oceanic plates since their formation. Extensive reworking and destruction of the cratonic lithosphere mainly occurred in eastern China during the Mesozoic to Cenozoic, which leaves distinct geochemical and geophysical signatures. Specifically, the Korean Peninsula (KP) is known to consist of Archean–Proterozoic massifs (e.g., Gyeonggi, Yeongnam Massif) located in the forefront in northeast Asia, where current dynamics in the upper mantle and effects due to nearby subducting slabs are the most significant.</p><p>Here we present, for the first time in detail, 3-D velocity structure of KP by teleseismic body wave traveltime tomography. Detailed P-wave and S-wave images of the crust and upper mantle were constructed by approximately 5 years of data from dense arrays of seismometers. We newly found a thick high-velocity body beneath the southwestern KP with a thickness of ~150 km, which is thought as a fragment of lithospheric root beneath the Proterozoic Yeongnam Massif. Also, we found low velocities beneath the Gyeonggi Massif, eastern KP margin, and Gyeongsang continental arc-back-arc system, showing significant velocity contrasts (dlnVp of ~4.0% and dlnVs of ~6.0%) to the high-velocity structure. These features indicate significantly modified regions. In addition, there was a clear correlation of the upper mantle low-velocity anomalies and areas characterized by Cenozoic basaltic eruptions, high heat flow, and high tomography, suggesting that there are close associations between mantle dynamics and recent tectonic reactivation.</p><p>The presence of a remnant cratonic root beneath the KP and contrasting lithospheric structures across the different Precambrian massifs suggests highly heterogeneous modification along the Sino-Korean craton margin, which includes the KP and North China Craton. A striking localization of lithosphere modification among the different Precambrian massifs within the KP suggests that the structural heterogeneity of the craton margin is likely sharp in scale and thickness within a confined area. We suggest that intense interaction of upper mantle dynamics and inherent structural heterogeneities of a craton margin played an important role in shaping the current marginal lithosphere structure in northeast Asia.</p>

Mantle dynamics of Western Pacific and East Asia: Insight from seismic tomography and mineral physics

2007 ◽  
Vol 11 (1-2) ◽  
pp. 120-131 ◽  
Author(s):  
Dapeng Zhao ◽  
Shigenori Maruyama ◽  
Soichi Omori
Keyword(s):  
East Asia ◽  
Seismic Tomography ◽  
Western Pacific ◽  
Mantle Dynamics ◽  
Mineral Physics

Contrasted East Asia and South America tectonics driven by deep mantle flow

2019 ◽  
Vol 517 ◽  
pp. 106-116 ◽  
Author(s):  
Ting Yang ◽  
Louis Moresi ◽  
Michael Gurnis ◽  
Shaofeng Liu ◽  
Dan Sandiford ◽  
...  
Keyword(s):  
South America ◽  
East Asia ◽  
Mantle Flow ◽  
Deep Mantle

scholarly journals Upper Mantle Anisotropy beneath the Western Segment, NW Indian Himalaya, Using Shear Wave Splitting

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Shubhasmita Biswal ◽  
Sushil Kumar ◽  
Sunil K. Roy ◽  
M. Ravi Kumar ◽  
W. K. Mohanty ◽  
...  
Keyword(s):  
Shear Wave ◽  
Upper Mantle ◽  
Seismic Anisotropy ◽  
Western Himalaya ◽  
Shear Wave Splitting ◽  
Plate Motion ◽  
Indian Plate ◽  
Deformation Pattern ◽  
Mantle Flow ◽  
Wave Splitting

Abstract This study investigates the upper mantle deformation pattern beneath the Indo-Eurasia collision zone utilizing the core-refracted (S(K)KS) phases from 167 earthquakes recorded by 20 broadband seismic stations deployed in the Western Himalaya. The 76 new shear wave splitting measurements reveal that the fast polarization azimuths (FPAs) are mainly oriented in the ENE-WSW direction, with the delay times varying between 0.2 and 1.7 s. The FPAs at most of the stations tend to be orthogonal to the major geological boundaries in the Western Himalaya. The average trend of the FPAs at each station indicates that the seismic anisotropy is primarily caused due to strain-induced deformation in the top ~200 km of the upper mantle as a result of the ongoing Indo-Eurasian collision. A contribution from the mantle flow in the direction of the Indian plate motion is possible. The mantle strain revealed in the present study may be due to a combination of basal shear resulting from plate motion and ductile flow along the collision front due to compression.

scholarly journals Mantle plumes and mantle dynamics in the Wilson cycle

2019 ◽  
Vol 470 (1) ◽  
pp. 87-103 ◽  
Author(s):  
Philip J. Heron
Keyword(s):  
Mantle Convection ◽  
Large Scale ◽  
Thermal Evolution ◽  
Mantle Flow ◽  
Mantle Plumes ◽  
Mantle Dynamics ◽  
The Core ◽  
Deep Mantle ◽  
Igneous Provinces ◽  
Wilson Cycle

AbstractThis review discusses the thermal evolution of the mantle following large-scale tectonic activities such as continental collision and continental rifting. About 300 myr ago, continental material amalgamated through the large-scale subduction of oceanic seafloor, marking the termination of one or more oceanic basins (e.g. Wilson cycles) and the formation of the supercontinent Pangaea. The present day location of the continents is due to the rifting apart of Pangaea, with the dispersal of the supercontinent being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The discussion presented here investigates theories regarding the thermal evolution of the mantle (e.g. mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Rifting, orogenesis and mass eruptions from large igneous provinces change the landscape of the lithosphere, whereas processes related to the initiation and termination of oceanic subduction have a profound impact on deep mantle reservoirs and thermal upwelling through the modification of mantle flow. Upwelling and downwelling in mantle convection are dynamically linked and can influence processes from the crust to the core, placing the Wilson cycle and the evolution of oceans at the forefront of our dynamic Earth.

Imaging the East Asia using waveform tomography with massive datasets 

2021 ◽  
Author(s):  
Hui Dou ◽  
Sergei Lebedev ◽  
Bruna Chagas de Melo ◽  
Baoshan Wang ◽  
Weitao Wang
Keyword(s):  
East Asia ◽  
Mantle Plume ◽  
Upper Mantle ◽  
High Velocity ◽  
Deep Structure ◽  
Indian Plate ◽  
Low Velocity ◽  
Velocity Anomaly ◽  
The Pacific ◽  
Velocity Anomalies

<p>We present a new shear-wave velocity model of the upper mantle beneath the East Asia, ASIA2021, derived using the Automatic Multimode Inversion technique. We use waveform fits of over 1.3 million seismograms, comprising waveforms of surface waves, S and multiple S waves.  In total, data from 9351 stations and 23344 events constrain ASIA2021, which maps in detail the structure of the lithosphere and underlying mantle beneath the region. Our model reveals deep structure beneath the tectonic units that make up East Asia. It shows agreement with previous models at larger scales and, also, sharper and stronger velocity anomalies at smaller regional scales. High-velocity continent roots are mapped in detail beneath the Sichuan Basin, Tarim Basin, Ordos Block, and Siberian Craton, extending to over 200 km depths. The lack of a high-velocity continental root beneath the Eastern North China Craton (ENCC), underlain, instead, by a low-velocity anomaly, is consistent with the destruction of this Archean nucleus. Strong low-velocity anomalies are mapped within the top 100 km beneath Tibet, Pamir, Altay-Sayan area, and back-arc basins. At greater depths, ASIA2021 shows high-velocity anomalies related to the subducted and underthrusted lithosphere of India beneath Tibet and the subduction of the Pacific and other plates in the upper mantle. In the mantle transition zone (MTZ), we find high-velocity anomalies probably related to deflected subducted slabs or detached portions of ancient continent cratons. In particularly, ASIA2021 reveals separate bodies, probably originating from the Indian Plate lithosphere beneath central Tibet, with one at 100-200 km beneath Songpan-Ganzi Block (SGFB) and the other in the MTZ. A strong low-velocity anomaly extending from the surface to the lower mantle beneath Hainan volcano and South China Sea is consistent with the hypothesis of the Hainan mantle plume. The high-velocity anomaly beneath ENCC in MTZ can be interpreted as a detached Archean continent root. The Pacific Plate subducts beneath the eastern margin of Asia into the MTZ and appears to deflect and extend horizontally as far west as the Songliao Basin. The absence of major gaps in the stagnant slab is consistent with the origin of Changbaishan volcano above being related to the Big Mantle Wedge, proposed previously. The low-velocity anomalies down to ~ 700 km depth beneath the Lake Baikal area suggest a hot upwelling (mantle plume) feeding the widely distributed Cenozoic volcanoes in central and western Mongolia.</p>

THE ROLE OF DEEP MANTLE FLOW IN SHAPING THE HAWAIIAN-EMPEROR BEND

2017 ◽  
Author(s):  
Simon Williams ◽  
◽  
Rakib Hassan ◽  
Dietmar Müller ◽  
Michael Gurnis ◽  
...  
Keyword(s):  
Mantle Flow ◽  
Deep Mantle
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