Magnetotelluric and DC Dipole-Dipole Soundings in Northern Wisconsin.

摘要

During the summer of 1974 this Laboratory participated in a joint study of the crust in northern Wisconsin with the Colorado School of Mines, the University of Wisconsin at Madison and others. The Wisconsin Arch region was selected for the large areal extent of outcrop of highly resistive crystalline basement rocks considered most favorable for possible lithospheric propagation of low frequency electromagnetic waves. The principal objective of the joint study was the determination of the maximum resistivity and thickness of a highly resistant zone underlying a thin surface layer of glacial till over most of the area. It was recognized at the outset that a combination of deep DC resistivity sounding, which can determine the resistivity-thickness product of the resistant zone, and the magnetotelluric method, which can determine its thickness, would be required.