Magnetotelluric Studies of Active Continent–Continent Collisions |
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| Authors: | Martyn Unsworth |
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| Institution: | (1) Department of Physics, University of Alberta, Edmonton, AB, T6G 0B9, Canada |
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| Abstract: | Continent–continent collisions are an important tectonic process and have played a fundamental role in the evolution of the
modern continents. A combination of geological and geophysical data has provided new constraints on the structure and temporal
evolution of these orogens. Magnetotelluric (MT) studies have been an important part of these studies since they can constrain
the fluid content and thermal structure which are key parameters for defining the rheology of the crust and upper mantle.
MT studies of the Himalaya have defined the geometry of active faults associated with continued plateau growth. Orogen scale
MT studies have shown that both the India–Asia collision (Tibetan Plateau and Himalaya) and the Arabia–Eurasia collision (Eastern
Anatolia) have developed a low resistivity mid-crustal layer with upper surface at 10–20 km that is likely due to a combination
of partial melt and associated aqueous fluids. The properties of this layer are consistent with a strength contrast that permits
crustal flow over geological timescales. The upper mantle from the Moho to at least 100 km beneath both Northern Tibet and
the Anatolian Plateau is characterized by low resistivity values (10–30 Ωm) indicating the presence of shallow asthenosphere.
Future integrated seismic and MT studies of collision zones are needed fully to explore the 3D structures associated with
deformation and further constrain geodynamic models. |
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