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Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data

Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data
Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data
We undertake a petrologically driven approach to jointly model magnetotelluric (MT) and seismic surface wave dispersion (SW) data from central Tibet, constrained by topographic height. The approach derives realistic temperature and pressure distributions within the upper mantle and characterizes mineral assemblages of given bulk chemical compositions as well as water content. This allows us to define a bulk geophysical model of the upper mantle based on laboratory and xenolith data for the most relevant mantle mineral assemblages and to derive corresponding predicted geophysical observables. One-dimensional deep resistivity models were derived for two groups of MT stations. One group, located in the Lhasa Terrane, shows the existence of an electrically conductive upper mantle layer and shallower conductive upper mantle layer for the other group, located in the Qiangtang Terrane. The subsequent one-dimensional integrated petrological-geophysical modeling suggests a lithosphere-asthenosphere boundary (LAB) at a depth of 80–120 km with a dry lithosphere for the Qiangtang Terrane. In contrast, for the Lhasa Terrane the LAB is located at about 180 km but the presence of a small amount of water in the lithospheric mantle (<0.02 wt%) is required to fit the longest period MT responses. Our results suggest two different lithospheric configurations beneath the southern and central Tibetan Plateau. The model for the Lhasa Terrane implies underthrusting of a moderately wet Indian plate. The model for the Qiangtang Terrane shows relatively thick and conductive crust and implies thin and dry Tibetan lithosphere.
magnetotelluric soundings, Tibet, integrated geophysical-petrological modeling, surface wave dispersion curves, water in the mantle
1525-2027
3965-3988
Vozar, Jan
6c8b62e2-6d13-4680-a9f0-c2d7cfa14df2
Jones, Alan G.
12cf33d1-b94f-4371-9084-7c643a4085d9
Fullea, Javier
fa998dd9-ed3b-49dd-811a-f4c929450306
Agius, Matthew R.
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Lebedev, Sergei
f6d20961-82f2-4faa-a66b-3951bb33c634
Le Pape, Florian
9e7fb3a6-ee00-4c09-bf59-6d152ce98cce
Wei, Wenbo
6fbd6bb5-3333-4ec7-8c0a-b2c2a3c47158
Vozar, Jan
6c8b62e2-6d13-4680-a9f0-c2d7cfa14df2
Jones, Alan G.
12cf33d1-b94f-4371-9084-7c643a4085d9
Fullea, Javier
fa998dd9-ed3b-49dd-811a-f4c929450306
Agius, Matthew R.
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Lebedev, Sergei
f6d20961-82f2-4faa-a66b-3951bb33c634
Le Pape, Florian
9e7fb3a6-ee00-4c09-bf59-6d152ce98cce
Wei, Wenbo
6fbd6bb5-3333-4ec7-8c0a-b2c2a3c47158

Vozar, Jan, Jones, Alan G., Fullea, Javier, Agius, Matthew R., Lebedev, Sergei, Le Pape, Florian and Wei, Wenbo (2014) Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data. Geochemistry, Geophysics, Geosystems, 15 (10), 3965-3988. (doi:10.1002/2014GC005365).

Record type: Article

Abstract

We undertake a petrologically driven approach to jointly model magnetotelluric (MT) and seismic surface wave dispersion (SW) data from central Tibet, constrained by topographic height. The approach derives realistic temperature and pressure distributions within the upper mantle and characterizes mineral assemblages of given bulk chemical compositions as well as water content. This allows us to define a bulk geophysical model of the upper mantle based on laboratory and xenolith data for the most relevant mantle mineral assemblages and to derive corresponding predicted geophysical observables. One-dimensional deep resistivity models were derived for two groups of MT stations. One group, located in the Lhasa Terrane, shows the existence of an electrically conductive upper mantle layer and shallower conductive upper mantle layer for the other group, located in the Qiangtang Terrane. The subsequent one-dimensional integrated petrological-geophysical modeling suggests a lithosphere-asthenosphere boundary (LAB) at a depth of 80–120 km with a dry lithosphere for the Qiangtang Terrane. In contrast, for the Lhasa Terrane the LAB is located at about 180 km but the presence of a small amount of water in the lithospheric mantle (<0.02 wt%) is required to fit the longest period MT responses. Our results suggest two different lithospheric configurations beneath the southern and central Tibetan Plateau. The model for the Lhasa Terrane implies underthrusting of a moderately wet Indian plate. The model for the Qiangtang Terrane shows relatively thick and conductive crust and implies thin and dry Tibetan lithosphere.

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More information

Accepted/In Press date: 20 August 2014
e-pub ahead of print date: 27 August 2014
Published date: October 2014
Keywords: magnetotelluric soundings, Tibet, integrated geophysical-petrological modeling, surface wave dispersion curves, water in the mantle
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 388021
URI: http://eprints.soton.ac.uk/id/eprint/388021
ISSN: 1525-2027
PURE UUID: 6a2df667-ecf3-4e7f-832c-707a9b6f3691

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Date deposited: 17 Feb 2016 16:18
Last modified: 14 Mar 2024 22:50

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Contributors

Author: Jan Vozar
Author: Alan G. Jones
Author: Javier Fullea
Author: Matthew R. Agius
Author: Sergei Lebedev
Author: Florian Le Pape
Author: Wenbo Wei

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