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A Magnetotelluric Survey of Ophiolites in the Neyriz area of southwestern Iran

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Abstract

A wide band magnetotelluric study of the ophiolitic zone of the Zagros orogenic belt was conducted in the Neyriz area of southwestern Iran. The purpose of the study was to image subsurface structures electrically and relocate the main Zagros thrust fault in the region. The thrust fault has a complex structure with obscure behavior and is believed to be located within a zone of ongoing continental plate convergence. The fault zone with a NW–SE geological trend is parallel to the Zagros orogenic belt and separates the Neyriz ophiolite assemblage from the adjacent Sanandaj-Sirjan metamorphic zone. Magnetotelluric data were collected along a SW–NE profile across the geologic strike; the study included 18 stations and modeling was performed using a 2-D inversion scheme. Analysis of both modes of magnetotelluric data (TE and TM) clarifies the signatures of large resistivity variation in the study area. Due to the presence of a high contrast in resistivity between the ophiolites and neighboring rocks, we are able to discern two sharp boundaries as faulting planes and borders of the ophiolite–radiolarite zone in the north-eastern and southwestern parts of the 2-D resistivity models, respectively.

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Acknowledgments

The Research Council of the University of Tehran (UT) is acknowledged for the financial support of the first author’s sabbatical leave at Uppsala University (UU) October 2011 to October 2012. The Department of Earth Sciences of UU is also appreciated for hosting the first author as a guest researcher and also for the use of instruments. Hemin Koyi is funded by the Swedish Research Council (VR). Weerachai Siripunvaraporn is acknowledged for the efficient 2-D inversion code of REBOCC. Maxim Smirnov is acknowledged for his updated processing code for MT data available at UU and Thomas Kalscheuer is acknowledged for providing his very helpful STRIKE and EMILIA codes. Masoud Dehghan and Mohammad Reza Gholamzadeh kindly helped us in the field. Constructive comments from two anonymous reviewers and the Editor are acknowledged.

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Authors and Affiliations

  1. Institute of Geophysics, University of Tehran, Tehran, Iran

    B. Oskooi & I. Mansoori

  2. Department of Earth Sciences, Uppsala University, Uppsala, Sweden

    L. B. Pedersen & H. A. Koyi

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  1. B. Oskooi
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  2. I. Mansoori
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  3. L. B. Pedersen
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  4. H. A. Koyi
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Correspondence to B. Oskooi.

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Oskooi, B., Mansoori, I., Pedersen, L.B. et al. A Magnetotelluric Survey of Ophiolites in the Neyriz area of southwestern Iran. Pure Appl. Geophys. 172, 491–502 (2015). https://doi.org/10.1007/s00024-014-0925-5

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