Vertical velocity of mantle flow of East Asia and adjacent areas |
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Authors: | Cheng Xianqiong Zhu Jieshou and Cai Xuelin |
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Institution: | (1) Department of Geophysics, Chengdu University of Technology, Chengdu, 610059, China |
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Abstract: | Based on the high-resolution body wave tomographic image and relevant geophysical data, we calculated the form and the vertical
and tangential velocities of mantle flow. We obtained the pattern of mantle convection for East Asia and the West Pacific.
Some important results and understandings are gained from the images of the vertical velocity of mantle flow for East Asia
and the West Pacific. There is an upwelling plume beneath East Asia and West Pacific, which is the earth’s deep origin for
the huge rift valley there. We have especially outlined the tectonic features of the South China Sea, which is of the “工”
type in the upper mantle shield type in the middle and divergent in the lower; the Siberian clod downwelling dives from the
surface to near Core and mantle bounary (CMB), which is convergent in the upper mantle and divergent in the lower mantle;
the Tethyan subduction region, centered in the Qinghai-Tibet plateau, is visible from 300 to 2 000 km, which is also convergent
in the upper mantle and divergent in the lower mantle. The three regions of mantle convection beneath East Asia and the West
Pacific are in accordance with the West Pacific, Ancient Asia and the Tethyan structure regions. The mantle upwelling originates
from the core-mantle boundary and mostly occurs in the middle mantle and the lower part of the upper mantle. The velocities
of the vertical mantle flow are about 1–4 cm per year and the tangential velocities are 1–10 cm per year. The mantle flow
has an effect on controlling the movement of plates and the distributions of ocean ridges, subduction zones and collision
zones. The mantle upwelling regions are clearly related with the locations of hotspots on the earth’s surface.
Translated from Geology in China, 2006, 33(4): 896–905 译自: 中国地质] |
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Keywords: | seismic body wave tomography East Asia mantle flow vertical velocity of flow tangential velocity of flow |
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