Conductivity discontinuities in the upper mantle beneath a stable craton

摘要: We present evidence for approximate collocation of seismic and electrical transitions in the upper mantle. More than two years very long period magnetotelluric (MT) data were recorded at a lakebottom observatory central Canadian Shield. After processing to contend with non-stationary source effects, removal galvanic distortion, underlying structure is 1D periods one hour four days. The response was extended 100 days by appending Geomagnetic Depth Sounding MT curves. Minimum linearised inversion, nonlinear extremal new genetic algorithm hypothesis testing, reveal discrete jumps conductivity depths near major mantle discontinuities. occur over limited depth ranges.