Thermoluminescence as a new research tool for the evaluation of geothermalactivity of the Kakkonda geothermal system, northeast Japan

The thermoluminescence glow-curve of quartz in volcanic and pyroclastic roc ks of the Miocene and Quaternary in the Kakkonda geothermal field was divid ed into L (low), M (medium) and H (high) peaks in order of increasing tempe rature. Thermoluminescence emission is independent of stratigraphic boundar ies but it is closely related to surface geothermal manifestations. Thermal ly stimulated processes of thermoluminescence caused by natural annealing o ccurred in the Quaternary after the eruption of the Tamagawa Welded Tuffs; radiation storage processes then began, as a consequence of the temperature drop. Thermoluminescence behavior indicates natural temperature manifestat ions, together with the paleo-temperature history. The H peak was thermally stable compared to the L and M peaks, and the area within which the relative intensity of the H peak is less than 5% coincide s with the surface zone where dominant fluid flow is convective. In additio n, L and M peaks indicate that a relatively low-temperature fluid mixes wit h the hot upflow around the western margin of the ascending flow zone. Thermoluminescence characteristics reflect paleo-temperature history and ar e related to geothermal fluid flow. Thermoluminescence is an effective expl oration technique for evaluating natural temperature manifestations and sub terranean heat flow in geothermal systems. (C) 2000 CNR. Published by Elsev ier Science Ltd. All rights reserved.