Mineralization of the South Hangai Fault Zone and the Bayankhongor Ophiolite Belt, west-central Mongolia, imaged with electrical resistivity models

Abstract

Electrical resistivity is a key parameter for mineral exploration and Mongolia is an important world mineral producer. We present magnetotelluric data acquired in a large regional array across west-central Mongolia. This is the first study of its kind in Mongolia. We will focus on key areas of mineralization, which are of economic importance, namely the South Hangai Fault Zone and the Bayankhongor Ophiolite Belt. The survey area, located between the uplifted Hangai Dome and the Gobi-Altai Mountains, represents an ancient suture zone. The magnetotelluric data are used to generate electrical resistivity models of the crustal structure, which was previously poorly understood.

While the cratonic upper crust is highly resistive, the low-resistivity South Hangai Fault Zone is detected and is revealed to be a major crustal-scale structure. Anomalous, low-resistivity zones in the crust are spatially associated with the surface expressions of the fault zone, known mineralization, and shallow surface resource extraction projects. By combining our electrical resistivity results with other geological and petrological data we attempt to gain insights into the mineral resources of this region.