Computed Dipole Resistivity Effects for an Earth Model with Vertical and Lateral Contrasts in Resistivity,

摘要

The dipole sounding method has been used by several investigators in attempts to determine the maximum resistivity in the earth's crust. The results of such surveys have shown that apparent values of measured resistivity pass through a maximum at dipole spacings of several tens to a hundred kilometers. In interpretation,this behavior is interpreted as indicating the leakage of current through the resistant part of the crust into more conductive regions in the mantle. Computer model studies of the effects of lateral changes in resistivity,as directed in this report,indicate that the maximum on a dipole sounding curve can be caused by a wide variety of lateral changes in resistivity,as well as by leakage of current into the mantle. When this happens,the value for the resistivity-thickness product representing the resistant part of the crust can be underestimated by a large amount. (Modified author abstract)