A preliminary study on electrical structure and dynamics of the ultra-high pressure metamorphic belt beneath the Dabie Mountains

Magnetotelluric data along a profile in the East Dabie Mountains has been collected along the profile across the ultra-high pressure metamorphic belt of NNE direction. According to the two-dimensional electrical structure of crust-upper mantle of the Dabie orogen, the North Huaiyang tectonic belt and Dabie block are different tectonic units in electrical structure. They are separated by the Xiaotian-Mozitan fault, which dips north and shows decoupling at the mid-upper crust level. Four electrical layers can be determined from surface to depth, which are the surficial weathering layer, the mid-upper crust high resistivity layer, the inner-crust relatively high conductive layer and the mantle layer. In the Dabie block, the mid-upper crust is mainly of high resistivity, corresponding to the distribution area of high-ultrahigh pressure metamorphic rock, its thickest place is between Yuexi and Yingshan. In the Dabie block, there maybe exist channels of granitic magma activity of the Yanshan Period, which make further uplift of the ultra-high pressure metamorphic rocks and affect the distribution of inner-crust high conductive layers and cause great difference in depth of the high conductive layer.