Isotope and chemical compositions and flow processes of Kuzu hot springs at the eastern foot of the North Alps, Nagano

Abstract

Hydrogen and oxygen isotopes and tritium (³H) analyses of hot spring waters from three locations in the Kuzu Hot Spring area at the eastern foot of the Northern Alps were carried out to estimate the origin, flow mode and heat source of the hot spring water. The Kuzu hot spring was an intermediate type of sodium chloride and sodium bicarbonate. Based on the results of tritium, hydrogen, and oxygen isotope analyses, the hot spring water was of meteoric water origin, at least prior to the late 1980s, and precipitation that fell in the surrounding mountainous area. It was presumed that the water is heated in the Pliocene granitic bodies as it infiltrates underground, and then flows out of the highly permeable layers along the Takase River.