Electromagnetic imaging of deep fluids in Archean crust.

摘要

Data collected over the Kapuskasing Structural Zone (KSZ) of the Archean Superior Province in central Canada were depth image processed in an attempt to determine the structure associated with the resistive upper crust in the region. Two conductive horizons beneath the overburden are imaged at 2 and 5 km depth with conductances of approximately 0.05 S and 0.15 S respectively.;The data collected across the KSZ were strongly contaminated by local galvanic effects associated with an inhomogeneous overburden covering the region. To approximate the contaminated data, synthetic channeling responses, generated using inhomogeneous thin sheet algorithms, were superimposed on a layered earth response. The layered earth response used was that indicated by the depth imaging and an inversion of the data to a layered earth structure. The synthetic responses were depth image processed using single- and multi-fold geometries to investigate the reliability of the conductivity estimation from data strongly distorted by galvanic effects. (Abstract shortened by UMI.)