Figure 1. Variations of the 3He/4He ration in the ground fluids with time. Sampling sites: (1) Angara Health Resort area, hole (Irkutsk amphitheater); (2) Shibertu Spring (Khangai), (3) Chulutu Spring (Khangai); (4) Khudzhirte Spring (Khangai); (5) Khakusskii Spring (North Baikal Basin); (6) Khalun-Us Spring (Khangai); (7) Khuldzhi Spring (Khangai); (8) Bulnai Spring (Khubsugul Basin); (9) Goryachinskii Spring (Middle Baikal Basin); (10) Sukhaya Zagza area, hole (Middle Baikal Basin): Khudzhirte Spring (Khangai); (11) Yamarovka Health Resort area, Hole 110 (Trans Baikal area); (12) Orgyl Spring (Khentei Kerulen Zone); (13) Urta Spring (Khentei Kerulen Zone); (14) Ulkhen Spring (Khubsugul Basin), (15) Zhemchug area, Holes R-1 and G-1 (Tunka Basin); (16) Arshan Resort Area, Holes 26, 28, 39, and Glaznoi Spring (Tunka Basin).