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Electrical structure of the Himalaya of Central Nepal: high conductivity around the mid-crustal ramp along the MHT

Lemonnier, Carole and Marquis, Guy and Perrier, Frédéric and Avouac, Jean-Philippe and Chitrakar, Gyani and Kafle, Basantha and Sapkota, Som and Gautam, Umesh and Tiwari, Dilliram and Bano, Maksim (1999) Electrical structure of the Himalaya of Central Nepal: high conductivity around the mid-crustal ramp along the MHT. Geophysical Research Letters, 26 (21). pp. 3261-3264. ISSN 0094-8276. http://resolver.caltech.edu/CaltechAUTHORS:20120910-135523937

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Abstract

Twelve broadband magnetotelluric (MT) soundings were performed across the Himalaya of Central Nepal in 1996 in order to determine the electrical structure of the crust and its relation to geological structures and active tectonics. The MT impedance tensors were obtained for frequencies between 0.001 and 500 Hz. The 2‐D section, derived from joint inversion of TE‐ and TM mode after RRI and Groom/Bailey decomposition, shows high conductivity in the foreland basin (∼30 Ω.m) that contrasts with the resistive Indian basement (>300 Ω.m) and Lesser Himalaya (>1000 Ω.m). In addition, our MT sounding reveals a major conductive feature beneath the front of the Higher Himalaya, also characterized by intense microseismic activity, and the position of a mid‐crustal ramp along the major active thrust fault (MHT). This high conductivity zone probably reflects metamorphic fluids, released during underthrusting of the Indian basement and pervading well connected microcracks induced by interseismic stress build‐up, or distributed brittle deformation around the ramp.


Item Type:Article
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http://dx.doi.org/10.1029/1999GL008363DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/1999/1999GL008363.shtmlPublisherUNSPECIFIED
Additional Information:© 1999 American Geophysical Union. Received 18 May 1999; accepted 6 August 1999. We thank M.R. Pandey, R.P. Tandukar and P. Le Fort for support. R. Koirala. B. Tissot and J. Durand have been of great help during the field operations or the preparation of the experiment. Some of the software used in this study was 11cquired through the Geotools European Consortium. Funding was provided by CNRS/INSU IDYLHIM project and by the cooperation agreement between DASE/LDG and DMG. We also thank the anonymous reviewers for their helpful comments and suggestions.
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CNRS/INSUIDYLHIM
DASE/LDGUNSPECIFIED
DMGUNSPECIFIED
Record Number:CaltechAUTHORS:20120910-135523937
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120910-135523937
Official Citation:Lemonnier, C., G. Marquis, F. Perrier, J. Avouac, G. Chitrakar, B. Kafle, S. Sapkota, U. Gautam, D. Tiwari, and M. Bano (1999), Electrical structure of the Himalaya of central Nepal: High conductivity around the mid‐crustal ramp along the MHT, Geophys. Res. Lett., 26(21), 3261–3264, doi:10.1029/1999GL008363.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33972
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:11 Sep 2012 21:26
Last Modified:26 Dec 2012 16:08

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