Abstract

Central Mongolia is a region of prominent intracontinental surface deformation and intraplate volcanism. Here, the northward compressional regime due to the India Asia collision transitions to an eastward extrusion. This transition zone is dominated by the Hangai Dome, a low relief, intracontinental plateau with widespread young Cenozoic volcanism. The observed surface deformation and volcanism cannot be explained solely by plate tectonics due to the large distances to tectonic plate boundaries. Instead, crust-mantle interactions are required, such as lithospheric thinning or asthenospheric flow and dynamic topography. However, the exact nature of these interactions remains enigmatic, partly due to the lack of detailed images of the subsurface in the region.

To obtain this information, a magnetotelluric survey in the Hangai and Gobi-Altai region was conducted by ETH Zurich, the University of Münster, and the Institute of Astronomy and Geophysics of the Mongolian Academy of Sciences. The resulting dataset was inverted to obtain the first 3-D electrical resistivity model in the region. One of the main features in this model likely represents a non-uniform lithosphere-asthenosphere boundary that forms two localized asthenospheric upwellings at approximately 70 km.

In this talk I will give a short introduction to the magnetotelluric method and present our multi-scale approach to survey design and inversion process.