The assessment of influence by heat and hydrothermal water using electron spin resonance

Abstract

Abstract:In order to evaluate effects of geothermal anomalies at high-level radioactive wastes disposal sites, previous studies applying electron spin resonance (ESR) mesurement to various samples and objectives have been reviewed, such as low-temperature hydrothermal water, detailed analysis of paleotemperature, and spatial distribution of thermal effects. ESR measures unpaired electrons trapped at defects in mineral crystals, therefore crystallization can be regarded as initial condition as well as cooling. Some reports of ESR measurement on sinters and stalactite, which had been precipitated from hot springs and cold groundwater respectively, have been found. A few kinds of ESR signals show enhancement under heating condition to natural hydrothermal temperature, and this property had used to detailed analysis of heating temperature of archeological implements. In case that fracture zones provide paths to hydrothermal fluid, calculated ESR ages of altered country rocks are expected to be older depending on distances from fractures, that can be applied to estimate extent and intensity of thermal effects. However, no report has been found that examines long-time heating nor cooling process systematically, and such experiments are needed for this purpose.