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>

scholarly journals Insights from the P Wave Travel Time Tomography in the Upper Mantle Beneath the Central Philippines

2021 ◽  
Vol 13 (13) ◽  
pp. 2449
Author(s):  
Huiyan Shi ◽  
Tonglin Li ◽  
Rui Sun ◽  
Gongbo Zhang ◽  
Rongzhe Zhang ◽  
...  
Keyword(s):  
Travel Time ◽  
Upper Mantle ◽  
High Velocity ◽  
Velocity Structure ◽  
The Philippines ◽  
P Wave ◽  
The South ◽  
Teleseismic Tomography ◽  
The North ◽  
Velocity Anomalies

In this paper, we present a high resolution 3-D tomographic model of the upper mantle obtained from a large number of teleseismic travel time data from the ISC in the central Philippines. There are 2921 teleseismic events and 32,224 useful relative travel time residuals picked to compute the velocity structure in the upper mantle, which was recorded by 87 receivers and satisfied the requirements of teleseismic tomography. Crustal correction was conducted to these data before inversion. The fast-marching method (FMM) and a subspace method were adopted in the forward step and inversion step, respectively. The present tomographic model clearly images steeply subducting high velocity anomalies along the Manila trench in the South China Sea (SCS), which reveals a gradual changing of the subduction angle and a gradual shallowing of the subduction depth from the north to the south. It is speculated that the change in its subduction depth and angle indicates the cessation of the SCS spreading from the north to the south, which also implies that the northern part of the SCS opened earlier than the southern part. Subduction of the Philippine Sea (PS) plate is exhibited between 14° N and 9° N, with its subduction direction changing from westward to eastward near 13° N. In the range of 11° N–9° N, the subduction of the Sulu Sea (SS) lies on the west side of PS plate. It is notable that obvious high velocity anomalies are imaged in the mantle transition zone (MTZ) between 14° N and 9° N, which are identified as the proto-SCS (PSCS) slabs and paleo-Pacific (PP) plate. It extends the location of the paleo-suture of PSCS-PP eastward from Borneo to the Philippines, which should be considered in studying the mechanism of the SCS and the tectonic evolution in SE Asia.

Deep velocity image of the north Zagros collision zone (Iran) from regional and teleseismic tomography

2019 ◽  
Vol 219 (3) ◽  
pp. 1729-1740 ◽  
Author(s):  
M Rahmani ◽  
K Motaghi ◽  
A Ghods ◽  
F Sobouti ◽  
M Talebian ◽  
...  
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
Velocity Structure ◽  
Central Iran ◽  
P Wave ◽  
Arabian Plate ◽  
Zagros Mountains ◽  
Teleseismic Tomography ◽  
The North ◽  
Collision Zone

SUMMARY We inverted 3555 regional and teleseismic P-wave relative time residuals to resolve deep velocity structure beneath the NW part of the Zagros collision zone. The data were gathered by 46 seismic stations installed along a ∼520-km-long seismic profile crossing the Zagros Mountains, Central Iran and the western Alborz Mountains. The obtained tomogram reveals a high velocity lithospheric root beneath the Zagros Mountains and a low velocity wedge in the frontal edge of the Arabian Plate beneath the suture that might be interpreted as beginning of delamination of lower part of the Arabian mantle lithosphere from its upper part. A significant deep (depth >350 km) high velocity feature is observed in the lower part of the upper mantle to the north of the Zagros suture and beneath Central Iran. We interpret this feature as the remains of oceanic slab of the Neotethys lying in the lower portion of the upper mantle and the transition zone.

Crust-mantle velocity structure in Shanxi rift, Central North China Craton

2020 ◽  
Author(s):  
Yan Cai ◽  
Jianping Wu
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Velocity Structure ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
The North ◽  
Shanxi Rift

<p>North China Craton is the oldest craton in the world. It contains the eastern, central and western part. Shanxi rift and Taihang mountain contribute the central part. With strong tectonic deformation and intense seismic activity, its crust-mantle deformation and deep structure have always been highly concerned. In recent years, China Earthquake Administration has deployed a dense temporary seismic array in North China. With the permanent and temporary stations, we obtained the crust-mantle S-wave velocity structure in the central North China Craton by using the joint inversion of receiver function and surface wave dispersion. The results show that the crustal thickness is thick in the north of the Shanxi rift (42km) and thin in the south (35km). Datong basin, located in the north of the rift, exhibits large-scale low-velocity anomalies in the middle-lower crust and upper mantle; the Taiyuan basin and Linfen basin, located in the central part, have high velocities in the lower crust and upper mantle; the Yuncheng basin, in the southern part, has low velocities in the lower crust and upper mantle velocities, but has a high-velocity layer below 80 km. We speculate that an upwelling channel beneath the west of the Datong basin caused the low velocity anomalies there. In the central part of the Shanxi rift, magmatic bottom intrusion occurred before the tension rifting, so that the heated lithosphere has enough time to cool down to form high velocity. Its current lithosphere with high temperature may indicate the future deformation and damage. There may be a hot lithospheric uplift in the south of the Shanxi rift, heating the crust and the lithospheric mantle. The high-velocity layer in its upper mantle suggests that the bottom of the lithosphere after the intrusion of the magma began to cool down.</p>

Anisotropic upper mantle structures in northeast Asia from Bayesian inversions of ambient noise data

2020 ◽  
Author(s):  
Sang-Jun Lee ◽  
Seongryong Kim ◽  
Junkee Rhie
Keyword(s):  
Upper Mantle ◽  
Joint Inversion ◽  
Northeast Asia ◽  
Three Dimensional ◽  
Japan Sea ◽  
Mantle Dynamics ◽  
Noise Data ◽  
Deep Layers ◽  
Radial Anisotropy ◽  
Back Arc

<p>The northeast Asia region exhibits complex tectonic settings caused by interactions between Eurasian, Pacific, and Philippine Sea plates. Distributed extensional basins, intraplate volcanoes and other heterogeneous features in the region marked results of the tectonic processes, and their mechanisms related to mantle dynamics can be well understood by estimating radial anisotropy in the lithospherie and asthenospherie. We constructed a three-dimensional radial anisotropy model in northeast Asia using hierarchical and transdimensional Bayesian joint inversion techniques with different types of dispersion data up to the depth of the upper mantle (~ 160 km). Thick and deep layers with positive radial anisotropy (V<sub>SH</sub> > V<sub>SV</sub>) were commonly found at depths between 70 and 150 km beneath the continental regions. On the other hand, depths and sizes of layers with positive radial anisotropy become shallower and thinner (30 ~ 60 km) respectively beneath regions where experienced the Cenozoic extension. These variations in positive radial anisotropy for different tectonic regions can be understood with the context of extensional geodynamic processes in back arc basins within the East Sea (Japan Sea). Interestingly, the most predominant positive radial anisotropy is imaged along areas with large gradient of the litheosphere-asthnosphere boundary beneath intraplate volcanoes. These observations favor the mechanism of edge-driven convection caused by the difference in lithosphere thickness and localized sublithospheric lateral flow from the continental region to back arc basins.</p>

Sign in / Sign up

Export Citation Format

Share Document