Induced-Polarization Response of Selected Cascades Core Samples

Abstract

We have measured the induced polarization (IP) phase response of core from the Medicine Lake Burnt Lava hole 62-21 and from the Clackamas Thermal Gradient Hole #1. The core samples were weakly to moderately clay altered, with the alteration of low temperature origin. The phase values at 1/64 Hz ranged in magnitude from 2 made to 16 made. Cation exchange capacities (CEC"s) ranged form 3 meq/100gms to 40 meq/100gms. There was linearity between the phase and log (CEC) for hematite poor rocks form flow interiors. We also observed linearity between log (CEC) and phase for all but one flow breccias sample. The remaining flow breccias sample was unique in possessing a large number of zeolite filled interconnecting vesticales. Its phase response was the highest measured. Our work demonstrates that Cascades rocks, when subjected to low temperature alteration can have significant IP response.