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Journal: |
Nature & Nature Geoscience 2010 No.3
clicks:843 |
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Title:
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Author:
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Denghai Bai1, Martyn J. Unsworth2, Max A. Meju3, Xiaobing Ma1, Jiwen Teng1, Xiangru Kong1, Yi Sun4, Jie Sun5, Lifeng Wang5, Chaosong Jiang6, Ciping Zhao6, Pengfei Xiao1 & Mei Liu1 |
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Adress: |
1.State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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Abstract:
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The ongoing collision of the Indian and Asian continents has created the Himalaya and Tibetan plateau through a range of deformation processes. These include crustal thickening, detachment of the lower lithosphere from the plate (delamination) and flow in a weakened lower crust1, 2, 3, 4, 5, 6. Debate continues as to which of these processes are most significant7. In eastern Tibet, large-scale motion of the surface occurs, but the nature of deformation at depth remains unresolved. A large-scale crustal flow channel has been proposed as an explanation for regional uplift in eastern Tibet6, 8, 9, but existing geophysical data10, 11 do not constrain the pattern of flow. Magnetotellurics uses naturally occurring electromagnetic waves to image the Earth’s subsurface. Here we present magnetotelluric data that image two major zones or channels of high electrical conductivity at a depth of 20-40 km. The channels extend horizontally more than 800 km from the Tibetan plateau into southwest China. The electrical properties of the channels imply an elevated fluid content consistent with a weak crust12, 13 that permits flow on a geological timescale. These findings support the hypothesis that crustal flow can occur in orogenic belts and contribute to uplift of plateaux. Our results reveal the previously unknown complexities of these patterns of crustal flow. |
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