Author/Authors :
Mahara، نويسنده , , Yasunori and Ohta، نويسنده , , Tomoko and Morikawa، نويسنده , , Noritoshi and Nakano، نويسنده , , Takanori and Tokumasu، نويسنده , , Minoru and Hukutani، نويسنده , , Satoshi and Tokunaga، نويسنده , , Tomochika and Igarashi، نويسنده , , Toshifumi، نويسنده ,
Abstract :
Dating using a combination of 3H and 3He is believed to be the most practical method for estimating the short residence time of shallow groundwater. However, this method must estimate tritiogenic 3He alone and tends to overestimate the residence time of groundwater, if terrigenic 3He from the mantle cannot be excluded from the total dissolved 3He. We demonstrate the exclusion of terrigenic 3He in the Saijo Basin, where mantle He is easily released along the major active fault, Median Tectonic Line. The 3He/4He ratios suggest that the west bank of the Kamo River, which lies within the basin, has experienced greater emanations of mantle He than the east bank. We estimate the residence times to be 1.1–96 years by the proposed exclusion method.
