Abstract
50 hotspring waters in Osaka Prefecture were studied on the geochemical characterization and those origins. The groundwaters can be classified into 3 groups based on the major element chemistry. 1: Dilute and cold calcium-bicarbonate water, occasionally contains carbon-dioxide, issued mostly from the fracture of basement rocks and shallow Quaternary sediments. 2: Dilute sodium-bicarbonate water taken from the lower fresh water formation of Quaternary Osaka Group. 3: Saline water, occasionally associating with carbon-dioxide, taken from the lowermost part of the Osaka Group formation and underlying basement granitic rocks. The latter groundwater are grouped into fossil seawater and Arima-type brine, which shows oxygen shift.
