Analyses of chemical compositions and hydrogen and oxygen isotopic ratios were carried out for 167 hot and cold spring waters from Abukuma area, northeasten part of Ibaraki, eastern part of Fukushima and southeastern part of Miyagi Prefectures, northeast Japan.
As a result, followings were concluded.
(1) Heat sources of all hot springs were able to be explained by conductive heat flow in this area, except those in the western side of the Abukuma River, near the volcanic front of northeast Japan.
(2) Vertical variation of geochemical characteristics of hot spring waters in this area was Cl type at the lowermost part, followed by Cl-SO4 and Cl-HCO3 types at the lower part, Cl/SO4/HCO3 types at the upper part, and SO4 type and SO4/HCO3 types at the uppermost part.
(3) Hot spring waters in this area were categorized into two types by their origins. The first type of hot spring waters were originated from interstitial water or oil field brine which had very high chloride ion concentration and very low sulfate ion concentration. The second type of hot spring waters were originated from meteoric water. Chloride and sulfate ions in them were leached out from minerals in layers which had both high chloride and sulfate ion concentration, although chloride ion in them had a possibility for the origin from brine in layers.