Widespread fluids in the Tibetan crust
Wei, W., M. Unsworth, A.G. Jones, T. Handong, K.D. Nelson, J.R. Booker, L. Chen,
S. Li, K. Solon, P. Bedrosian, S. Jin, M. Deng, J. Ledo, D. Kay and B. Roberts
Magnetotelluric (MT) exploration has shown that the middle and lower crust is anomalously
conductive across most of the north to south width of the Tibetan plateau. The integrated
conductivity (conductance) of the Tibetan crust ranges from 3000 to greater than 20,000 Siemens.
In contrast, stable continental regions typically exhibit conductances from 20 to 1000 S,
averaging 100 S. Such pervasively high conductance suggests that partial melt and/or aqueous fluids
are widespread within the Tibetan crust. In Southern Tibet the high conductivity layer is at a
depth of 15-20 km and probably due to partial melt and aqueous fluids in the crust. In Northern
Tibet the conductive layer is at 30-40 km and due to partial melting. Zones of fluid may represent
weaker areas that could accommodate deformation and lower crustal flow.
Science, 292, 716-718, 2001.
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Alan G Jones / 10 June 2004 /