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Abstract:
Lithosphere-asthenosphere boundary (LAB) is essential for tectonic plates as it is the base of the plates and enables movement of the plates. However, the nature of the LAB, including its depth, is still elusive. The definition of LAB varies from study to study by using different geophysical data. Oceanic LAB has a simpler history than continental LAB, therefore it is ideal to study the nature of LAB beneath the seafloor. Partial melt is one feature of LAB suggested in multiple geophysical and petrophysical studies. The magnetotelluric method is sensitive to partial melts and is one of the most effective methods to map partial melts and study LAB. Therefore, we have collected three different datasets in Northern Middle Atlantic Ridges to further study the electrical property of LAB. The eLAB at different latitudes is more dynamic than we previously thought. The resistivity model of LAB can be simple at one location and complicated at another location of the Mid-Atlantic Ridge. More interestingly, at some locations, the upwelling magma is not seen beneath the middle ocean ridge in the resistivity model, which is supposed to be the supplier of seafloor spreading materials. These findings enrich the understanding of the geodynamics of Earth and suggest that a more complicated model is necessary to represent LAB.
