Three-dimensional Magnetotelluric Modeling of data from Northeast of Gorgan Plain

Magnetotelluric measurements have been conducted in the period range of 0.005-128 s along five parallel east-west directed profiles including 85 sites totally in the north-eastern part of Gorgan Plain, Golestan Province, North of Iran; with the aim of exploring iodine. Distortion and dimensionality analysis of data imply the existence of a north-south elongated two-dimensional model with some localized three-dimensional effects, particularly at long periods, that has been mildly affected by non-inductive distortions. Exclusion of a very few data points with large values of distortion angles and rotation based on the selected azimuth of strike was followed by two-dimensional inversion of joint TE- and TM-mode apparent resistivity and phase data. After some resolution tests to ensure the reliability of the detected features, three-dimensional inversion of real and imaginary parts of full impedance tensor data was accomplished. Despite the reduced resolution of magnetotelluric data in a conductive environment, the elimination of part of the data due to hardware constraints and the lack of an ideal data acquisition pattern, the models showed some definite results. The resulted electrical resistivity models from both two- and three-dimensional inversion resolved highly conductive bodies as our exploration targets, which are expected to be saline aquifers containing iodine within the generally conductive sediments.