Thermoluminescene of quartz in volcanic and pyroclastic rocks from the Kakkonda geothermal area, Northeast Japan—Preliminary study of thermoluminescence geothermometer

Thermoluminescence of quartz in volcanic and pyroclastic rocks from the Kakkonda geothermal area was investigated. Thermoluminescence glow curve of quartz in the Tamagawa Welded Tuffs (reference sample) collected from a point 10km away from the Kakkonda geothermal power plant shows single peak which is in the range between about 280 to 330°C. Approaching the Kakkonda geothermal power plant, low temperature region of glow curve is depleted, and total emission of thermoluminescence decreases. Total emission is no relation to the stratigraphie boundaries. Five percent isopleth of relative emission compared with the total emission of the reference sample is located at a point about 2km away from the Kakkonda geothermal plant in a northwest to southeast direction along the Kakkonda river, and 1 to 2km in a northeast to southwest direction. The area enclosed with the isoplethes of relative emission below 40% is almost overlapped with sericite/montmorillonite mixed layer mineral zone. These features mean that the paleodose in quartz was decayed by geothermal activity and relative emission could be an indicator to estimate temperature and its duration. These results suggest that thermoluminescence of quartz from geothermal area is applicable to the evaluation of thermal influence and the prediction of the subterranean heat source in geothermal systems.